#USA, #Michigan DHHS confirms #human eastern equine #encephalitis case (August 19 '26)

 

Residents urged to take precautions against mosquito bites

LANSING, Mich. - The Michigan Department of Health and Human Services (MDHHS) has confirmed a locally acquired case of eastern equine encephalitis (EEE) in a Roscommon County resident and reminds Michiganders to take steps to protect themselves against mosquito-borne diseases.

    This is the first EEE human case reported in Michigan since 2021. 

    No additional information will be provided about this individual.

    State and local health departments, along with the Michigan Department of Agriculture and Rural Development and Michigan Department of Natural Resources, have been monitoring and will continue to monitor for signs of EEE in humans, mosquitos, domestic animals and wildlife. 

    Prior to this case, no animal EEE activity has been detected in Michigan this year. 

    Additional mosquito trapping and testing is underway in Roscommon County to assess the level of risk in the area. Information about human, animal and mosquito pool testing is available in a weekly arboviral report.

    “It is vital that Michigan residents take precautions against mosquito bites as mosquitoes can carry diseases that can have devastating health effects,” said Dr. Natasha Bagdasarian, chief medical executive. 

    “EEE is one of the most dangerous mosquito-borne diseases in the U.S., with a 30% fatality rate among people who become ill.”

    EEE virus is spread to people by the bite of an infected mosquito. EEE is a rare but serious disease. Only a few human cases are reported each year in the United States.  

    People who become ill with EEE may experience fever, headache, chills and nausea. In some cases, symptoms may progress to inflammation of the brain, signaled by disorientation, seizures and coma. 

    Physicians treating patients with these symptoms should consider testing for EEE and other mosquito-borne viruses and report suspect cases to their local health department. The MDHHS Bureau of Laboratories offers comprehensive testing for the arboviruses of concern in Michigan.

    The best way to prevent EEE, or any other mosquito-borne illness, is to reduce the number of mosquitoes around your home and to take steps to avoid mosquito bites, including:

        ° Use U.S Environmental Protection Agency-registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol and 2-undecanone. Follow the product label instructions and reapply as directed.

        ° Do not use insect repellent on children under 2 months old. Instead, dress your child in clothing that covers arms and legs and cover crib, stroller and baby carrier with mosquito netting.

        ° Wear shoes and socks, light-colored long pants and long-sleeved shirts when outdoors.

        ° Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings.

        ° Use bed nets when sleeping outdoors or in conditions with no window screens.

        ° Once a week eliminate all sources of standing water that can support mosquito breeding around your home, including water in bird baths, abandoned swimming pools, wading pools, old tires and any other object holding water.

    For more information on the human health impact of EEE, visit CDC.gov/EEE. For updates on EEE activity in Michigan, visit Michigan.gov/EEE.

Source: 

Link: https://www.michigan.gov/mdhhs/inside-mdhhs/newsroom/2026/08/19/eee

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#USA, Public health officials report first #Idaho #WNV #encephalitis case of 2026 (DoH, August 18 '26)

 

    Idaho’s first reported case of human West Nile virus (WNV) meningitis this year was identified in a Canyon County resident over the age of 65. This person had been hospitalized for the illness but is recovering at home. 

    WNV is spread by the bite of an infected mosquito and can lead to severe disease in some people. West Nile neuroinvasive disease is a rare but serious complication of West Nile virus infection that occurs when the virus affects the brain or spinal cord, causing conditions such as meningitis, encephalitis (swelling of the brain), or paralysis.

    “If you or someone you know takes medications that suppress your immune system, such as treatments for cancer, autoimmune diseases, or organ transplants, your risk of developing severe West Nile virus illness after a mosquito bite, including death may be up to 40% higher,” said Southwest District Health Epidemiologist Lekshmi Rita Venugopal. 

    “With West Nile virus detected in mosquitoes in Southwest Idaho again this summer, it's especially important for people with weakened immune systems to avoid mosquito bites.”

    Idaho State Epidemiologist Dr. Christine Hahn said public health officials strongly encourage Idahoans to protect themselves and their families from mosquito bites.

    “The report of the first severe West Nile virus disease of the season in an Idaho resident is a good reminder for all of us to take protective measures against mosquito bites,” she said. 

    “This includes wearing insect repellent and protective clothing in addition to reducing standing water around gardens and homes where mosquitoes can lay eggs.”

    Symptoms of WNV infection often include fever, headache, body aches, nausea, and sometimes swollen lymph glands or a skin rash. 

    WNV infection can result in severe illness, especially in people 50 years or older, leading to hospitalization and even death. Talk to your healthcare provider about testing for WNV to confirm your illness.

    There are no licensed vaccines or medicines to prevent WNV disease in people. 

    To protect against WNV infection, people should avoid mosquitoes, particularly between dusk and dawn when the mosquitoes that spread WNV are most active. 

    In addition, everyone should:

        § Wear long, loose-fitting shirts and pants when outdoors and apply DEET or other EPA-approved insect repellent to exposed skin and clothing. Carefully follow instructions on the product label, especially for children.

        § Keep mosquitoes outside the home by using screens on windows and doors or air conditioning, if available. Repair or replace damaged screens. 

        § Reduce standing water on property. Check and drain toys, flowerpots, buckets, kiddie pools, and other items left outdoors that can hold water.

        § Change bird baths, static decorative ponds, kiddie pools, and animal water tanks weekly to reduce suitable mosquito habitats.

        § Consider larvicides for bodies of water that will not be used for drinking and cannot be covered or dumped out.

    WNV activity in mosquitoes has been detected in seven Idaho counties this year by participating mosquito abatement districts.

    For more information, visit the following resources:

        ° https://westnile.idaho.gov

        ° www.cdc.gov/west-nile-virus/index.html

        ° www.epa.gov/insect-repellents

        ° www.cdc.gov/mosquitoes/mosquito-control/mosquito-control-at-home.html

        ° www.cdc.gov/han/php/notices/han00532.html

(...)

Source: 

Link: https://healthandwelfare.idaho.gov/news/public-health-officials-report-first-idaho-west-nile-virus-meningitis-case-2026

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#Netherlands, #WNV detected in a #blood #donor (RIVM, August 17 '26): First case since 2020

 

    A West Nile virus infection has been confirmed in a blood donor in the Netherlands. 

    This occurred in August 2026 during a Sanquin study among blood donors from areas where the West Nile virus had previously been detected in humans, horses, birds or mosquitoes. 

    A laboratory test (PCR) detected the virus in the donor, who had no symptoms and is still not showing any. 

    The person lives in the province of Utrecht and has not been abroad recently. It is therefore likely that the infection was contracted in the Netherlands.

First confirmed case of infection in a human in 2026

    This is the first confirmed case of a human infection in 2026 that originated in the Netherlands. The last time people contracted a West Nile virus infection in the Netherlands was in 2020.

West Nile virus and West Nile fever

    The West Nile virus occurs in birds. 

    The common house mosquito can contract the virus when feeding on the blood of an infected bird. 

    An infected mosquito can then pass the virus on to other birds, to mammals such as horses, and to humans. 

    Humans and horses can fall ill with the West Nile virus, but they cannot pass the virus on to others. 

    The disease caused by the West Nile virus is called West Nile fever. 

    80 per cent of people with West Nile fever have no symptoms, 19 per cent have flu-like symptoms and 1 per cent may develop neurological symptoms. 

    People over 50 and people with weakened immune systems due to illness or medication have a higher risk of becoming very ill from West Nile fever. 

    A small proportion of people who have a severe form of West Nile fever may die.

Mosquitoes capable of transmitting West Nile virus are active

    The fact that, within a short space of time, a horse, a bird and a human have now tested positive for the West Nile virus in different parts of the Netherlands shows that there are mosquitoes active in the Netherlands that carry the West Nile virus. It is still very unlikely for people in the Netherlands to contract West Nile fever.

What can you do to prevent West Nile virus?

    Mosquitoes are mainly active at dusk. To minimise the risk of being bitten, you could, for example:

        § wear clothing that covers the skin (long sleeves, long trousers)

        § keep mosquitoes out (insect screens for windows/doors)

        § use mosquito repellents on exposed skin

        § sleep under a mosquito net

Cooperation and monitoring

    Experts from organisations including the National Institute for Public Health and the Environment (RIVM), the GGDs, Erasmus MC, Royal GD, WBVR, UU, Sanquin and the NVWA are monitoring the situation closely.

Source: 

Link: https://www.rivm.nl/en/news/west-nile-virus-detected-in-a-blood-donor

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Seasonal #surveillance in #humans and #animals in 2026 for #WNV, Monthly Report (ECDC, August 12 '26): 245 cases so far

 

August 2026 | Produced on 12 August 2026 at 12:00 based on data submitted up until and including 5 August 2026

Epidemiological summary

Findings from human surveillance

    In 2026, and as at 5 August, seven countries in Europe have reported 245 locally acquired {1} human cases of West Nile Virus (WNV) infection. 

    The earliest and latest date of onset were on 12 May 2026 and 1 August 2026, respectively. 

    Locally acquired cases have been reported by Italy (139 cases), Greece (65, of which four with unknown place of infection), Spain (17 cases), North Macedonia (13 cases), Romania (six cases), France (four cases) and Germany (one case). 

    In Europe, 12 deaths have been reported by Greece (six deaths), Italy (five deaths) and Romania (one death).

    The number of human cases reported so far (245 cases) is below the average for the corresponding period over the past decade (403 cases). 

    However, reporting delays may result in an under-estimation of the current burden, as the 2026 data remain provisional, whereas the ten-year average is based on consolidated data from previous years. 

    In addition, this ten-year average is influenced by several particularly intense WNV transmission seasons, notably in 2018 (1 065 cases reported up to the corresponding week), 2022 (781 cases) and 2024 (654 cases).

    To date, most cases have been reported in Italy (139 cases) and Greece (65 cases). 

    Although the number of cases reported in Italy is lower than during the same period in 2025 (168 cases), it remains the most affected country in Europe in 2026. 

    Greece has reported more cases in 2026 than during the same period in 2025 (65 cases compared with 26 cases). 

    WNV circulation is currently most intense in the Attica NUTS 2 region (48 cases), with Anatoliki Attiki (East Attica, 34 cases) and Voreios Tomeas Athinon (North Athens, seven cases) most affected.

    As at 5 August 2026, locally acquired human cases of WNV infection had been reported in 58 NUTS 3 regions across seven countries. 

    This is higher than at the same point in 2025, when cases were reported in 40 NUTS 3 regions across six countries. 

    However, the geographical spread observed so far in 2026 remains well below the final extent recorded in recent seasons: by the end of 2025, affected regions numbered 160 and in 2024 there were 218. 

    The 2024 season remains the largest WNV season on record in terms of geographical spread.

    This year, six regions reported locally acquired human cases of WNV infection for the first time ever: France in Pyrénées-Orientales (FRJ15); Germany in Rhein-Pfalz-Kreis (DEB3I); Italy in Campobasso (ITF22) and Viterbo (ITI41); North Macedonia in Pelagoniski (MK005) and Vardarski (MK001).

    Similar to previous years, most cases were reported among males aged 65 years and above. 

    Most cases were hospitalised (72%) and presented with neurological symptoms (58%). 

    The proportion hospitalised was lower than the average reported during the previous decade (87%), while the proportion with neurological symptoms was also slightly lower than the historical 10-year average (64%). 

    The case fatality rate was approximately 5%, lower than the average reported during the previous decade (11%). 

    However, this estimate should be interpreted with caution, as clinical outcomes may not yet be known for all reported cases and additional deaths may be recorded as the season progresses and data are consolidated.

    Owing to delays in diagnosis and reporting, and because most WNV infections are asymptomatic or subclinical, the reported case numbers probably underestimate the true number of infections. Seasonal surveillance in humans primarily captures laboratory-confirmed cases, which may further contribute to reporting delays.

Findings from veterinary surveillance

    From the veterinary perspective, 17 WNV outbreaks among equids and 74 outbreaks among birds have been reported in Europe in 2026. 

    The earliest start date of an outbreak among equids and birds was on 30 March 2026 in France and 31 March 2026 in Italy, while the latest onset of an outbreak among equids and birds was, respectively, on 31 July 2026 in Netherlands and 28 July 2026 in Italy. 

    Outbreaks among equids have been reported by France (five outbreaks), Greece (five outbreaks), Italy (five outbreaks), the Netherlands (one outbreak) and Spain (one outbreak). 

    Outbreaks among birds have been reported by Italy (64 outbreaks), France (five outbreaks), Spain (three outbreaks), Austria (one outbreak) and Belgium (one outbreak).

    No information was available on the equid species involved in the outbreaks reported in the Animal Disease Information System (ADIS). 

    The bird species most frequently associated with the reported outbreaks were the common magpie (23) and the hooded crow (20), followed by the carrion crow (5), the common kestrel (5), the Eurasian blackbird (5), the yellow-legged gull (3), Adalbert’s eagle (2), the common wood-pigeon (2), and the little owl (2). 

    Single outbreaks were associated with the common loon, the common raven, the European turtle-dove, the golden eagle, the grey heron, the house sparrow and the northern goshawk.

    The monthly number of WNV outbreaks in equids reported during the first part of 2026 was comparable to the corresponding 10-year monthly average (2016−-2025). 

    However, the number of equid outbreaks in July 2026 remained below the levels observed in July 2018, 2024 and 2025, years characterised by particularly high WNV intensity. 

    In contrast, the number of WNV outbreaks in birds slightly exceeded the corresponding four-year monthly average (2022–2025) in April and May, and was substantially higher in June. 

    This trend reversed in July 2026, when the number of reported outbreaks in birds fell below the four-year average, although it remained higher than in July 2025. However, it should be noted that reporting delays may affect the July numbers, as some outbreaks occurring during that month may be notified in August.

    As at 5 August 2026, outbreaks in birds and/or equids have been reported in 43 NUTS 3 regions across seven countries. This compares with 55 regions (10 countries) during the same period in 2025 and 42 regions (eight countries) in 2024. All seven countries reported WNV outbreaks in birds and/or equids in 2025 and in prior years, reflecting endemic WNV activity in these territories. However, as at 5 August, outbreaks in birds and/or equids were reported to ADIS for the first time in the following six regions: by France in Hauts-de-Seine (FR105) and Seine-et-Marne (FR102); by Belgium in Arr. Namur (BE352), by Greece in Drama (EL514), by Italy in Genova (ITC33) and by the Netherlands in Delf en Westland (NL362).

Patterns across human and veterinary surveillance

    Four countries – France, Greece, Italy, and Spain – reported both human WNV infections and outbreaks in equids and/or birds. 

    As at 5 August, Italy accounted for most of the reported human cases (56.7%) and animal outbreaks (75.8%). 

    Greece reported the second-largest share of human cases (26.5%) but only five equid outbreaks and no bird outbreaks, representing 5.5% of all reported animal outbreaks.

    Differences in the patterns observed across European countries may reflect a combination of ecological, climatic and surveillance-related factors. 

    Favourable climatic conditions and the presence of ecological hotspots, such as wetlands and agricultural areas, may support mosquito vector populations and influence the distribution and behaviour of animal hosts, thereby facilitating WNV circulation. At the same time, differences in WNV surveillance systems across Europe may affect detection and reporting rates.

    The first indication of WNV activity may arise from either human or animal surveillance, depending on local epidemiology, detection capacity and surveillance system sensitivity. Therefore, the absence of reports from one sector should not be interpreted as evidence that WNV is not circulating. 

    In France (Pyrénées-Orientales, FRJ15), Greece (Drama, EL514), and Italy (Genova, ITC33), human cases were reported before, or in the absence of, notified outbreaks in birds or equids. 

    Conversely, in Belgium (Arr. Namur, BE352), France (Hauts-de-Seine, FR105 and Seine-et-Marne, FR102) and the Netherlands (Delft en Westland, NL362), animal detections preceded human cases. 

    Belgium is a relevant example, as WNV was first reported in the country in 2025 through avian surveillance, with no previous detections in humans and animals. In 2026, it has again been identified in birds in a previously unaffected region, highlighting the role of avian surveillance in detecting local virus circulation and geographical spread.

    Active mosquito surveillance is also important for the early detection of WNV circulation. However, results on WNV detection in mosquitoes are not included in this report because they are not legally required to be reported at European level, and the available information is therefore scattered and often project-based.

Seasonal outlook

    Given the favourable weather conditions for WNV transmission in Europe, ECDC and EFSA expect further human cases and outbreaks in equids and birds to be reported in the coming weeks. In previous years, transmission has typically peaked in August and September.

    ECDC and EFSA continue to closely monitor the situation in Europe.

(...)

Source: 

Link: https://www.ecdc.europa.eu/en/infectious-disease-topics/west-nile-virus-infection/surveillance-and-disease-data/monthly-updates

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Yellow #fever - #Global (WHO, D.O.N., June 24 '26, summary)

 

Situation at a glance

    Yellow fever is a viral disease found in areas of Africa and the Americas, spread by infected mosquitoes. 

    Following an increase of cases in the Americas in 2025, transmission activity remained into 2026. 

    From 1 January to 26 May 2026, six countries reported a total of 79 human infections along with multiple epizootics, indicating active sylvatic circulation. 

    In Africa, sustained activity continued across parts of the region, affecting 13 high-risk countries (as per classification in the Eliminate Yellow fever Epidemics (EYE) Strategy). 

    From January to May 2026, three countries in Africa reported 16 confirmed human cases, with an additional 32 suspected cases under investigation in five other countries. 

    The recent rapid risk assessment assessed geographical variations in vaccination coverage, evidence of viral circulation, and the presence of competent vectors, concluding that unvaccinated populations in countries or areas with a history of yellow fever transmission remain at greatest risk. 

    Transmission dynamics are further influenced by seasonal ecological factors, particularly rainfall, temperature, and mosquito abundance. 

    Outbreaks reported from October 2025 through May 2026 in countries or areas with a history of yellow fever transmission were generally consistent with seasonal patterns or reflected gaps in immunization coverage. 

    In contrast, cases detected in previously unaffected areas suggest viral introduction and an increased risk of urban transmission. 

    No imported cases were detected outside the two affected WHO regions, but expanding vector suitability, rapid urbanization, climate shifts, and increased mobility continue to create conditions conducive to international spread. 

    WHO emphasizes the importance of active surveillance, timely laboratory testing, cross-border coordination, and information sharing. 

    Vaccination remains the primary means for the prevention and control of yellow fever. 

    WHO continues to support countries in expanding vaccination coverage through routine immunization programmes and preventive vaccination campaigns to enhance population immunity and reduce the risk of outbreaks.

(...)

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON610

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Yellow Fever - Global Rapid #Risk #Assessment (WHO, June 17 '26, summary)

 

{Summary}

Overall Risk Statement 

    This rapid risk assessment (RRA) aims to assess the overall public health risk at the global level associated with the increase in yellow fever (YF) transmission in the Region of the Americas alongside ongoing YF activity reported in the WHO African Region, documented from the fourth quarter of 2025 through 2026 to date.  

    Together these events involve 13 out of the 40 countries with areas at high risk for YF transmission globally (currently 27 in Africa and 13 in the Americas under the Global Strategy to Eliminate Yellow Fever Epidemics (EYE) classification). 

    For this risk assessment, the WHO Secretariat considered the public health impact of YF, the risk of geographical spread to other WHO regions, and the risk associated with insufficient control capacities. 

    This RRA also provides an assessment of the overall risk in regions with a history of YF transmission, and other regions where the primary vector for urban YF transmission (Aedes aegypti) is present. 

    The overall public health risk also incorporates differences in vaccination status and the availability of epidemiological evidence of YF or arboviral circulation. 

    Unvaccinated populations in at-risk areas constitute the highest risk group; vaccinated populations in the same areas are considered low risk; and populations in areas with no available evidence of YF or indicative arboviral circulation are classified as low risk, albeit with low confidence due to limited surveillance data. 

    The assessment further integrates seasonal ecological dynamics, recognizing that although YF virus transmission can occur year-round in certain ecological zones, marked intra-annual variability exists. 

    In addition, the RRA assesses the risk to countries who do not have competent vectors, as well as the risk to travellers, considering their YF vaccination status. 

    YF outbreaks must be interpreted within their epidemiological and geographic context, as the dynamics of transmission, population immunity, and public health implications differ markedly between high risk and non- risk areas for YF transmission. 

    In high-risk areas, where the virus circulates continuously and population immunity varies, outbreaks may reflect seasonal patterns, gaps in routine immunization, or fluctuations in vector populations. 

    In contrast, outbreaks occurring in areas with no evidence available for YF—where population immunity is typically low and YF virus is not expected to circulate—raise additional concerns regarding viral introduction, the potential for rapid urban transmission, and the need for immediate vaccination and vector control measures, especially in urban settings, to prevent wider spread. 

    Understanding these contextual differences is essential for interpreting the epidemiology, identifying risk factors for severe disease, and determining the relevance and effectiveness of prevention and control strategies. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment--yellow-fever--global-v.1

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Rapid #risk #assessment: #Chikungunya virus disease, #Global (WHO, 24 April 2026, v2, summary)

{Summary)

Overall Risk statement

-- This rapid risk assessment aims to assess the overall public health risk posed by chikungunya virus (CHIKV) transmission in 2026 at the global level. 

-- It considers the potential risk to human health, the likelihood of geographical spread, limitations in prevention and control capacities, and the influence of regional seasonal patterns that favour Aedes mosquito activity, which could drive outbreaks during the 2026 transmission season. 

-- Chikungunya virus poses a significant and growing global health risk due to large and widespread regional outbreaks in recent years, lack of specific treatment, limited use of vaccine, and climate- and conveyance-driven mosquito range expansion, with increasing international travel. 

-- While mortality remains relatively low, the CHIKV infection can cause prolonged arthritis with disability as well as severe illness in some patients.

-- In 2025, an overall of 502 264 CHIKV disease cases including 208 335 confirmed cases, and 186 deaths were reported globally from 41 countries and territories, including autochthonous and imported cases in travellers. 

-- From 1 January to 31 March 2026, Chikungunya transmission was reported by 18 countries, with the vast majority of cases occurring in the Region of the Americas. 

-- Brazil and Bolivia account for 87% of cases in the Region; together with Argentina, Suriname, and Cuba, these five countries represent approximately 99% of reported cases. 

-- The European Region reported the second-highest number of cases, predominantly reported from French overseas departments, particularly Mayotte and La Réunion. 

-- Global aggregation is limited due to incomplete reporting.

-- With the rainy season about to begin in many regions in the coming months, cases of CHIKV are expected to rise, as rainfall events create favourable conditions for Aedes mosquito breeding and increase the risk of CHIKV transmission, including in previously unaffected areas. 

-- Transmission dynamics will also be impacted by the population immunity acquired from outbreaks in recent years. 

-- Peak CHIKV transmission months in the respective WHO regions include:

• Southeast Asia & Western Pacific: May–October

• Americas: May–November (Northern hemisphere)/November–March (Southern hemisphere)

• Continental Europe: June–September (main season) (transmission in overseas departments aligns with climatic conditions within their geographic location/proximity)

• Africa & Eastern Mediterranean: During/after local rainy seasons (varies by country)

-- The global public health risk posed by CHIKV transmission is assessed as moderate. 

-- This takes into account the widespread transmission and outbreaks across multiple WHO regions in 2025, which continued into early 2026, including in areas with previously low or no transmission. 

-- Ongoing transmission in parts of the Indian Ocean region, such as Seychelles, Mauritius and Mayotte demonstrates continued regional activity. 

-- The resurgence and emergence of cases in new geographic areas are facilitated by the presence of competent Aedes mosquito vectors, limited population immunity, favorable environmental conditions, and increased human mobility coupled with under-performing/disrupted health systems, particularly in fragile, conflict-affected and vulnerable countries- leading to poor control measures.

-- The uneven distribution of cases across regions complicates the interpretation of a global trend but highlights significant localized transmission. 

-- Prevention and control capacities remain challenged by gaps in surveillance, equitable access to quality-assured diagnostics and laboratory confirmation, healthcare infrastructure, and sustained vector surveillance and control management.

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---chikungunya-virus-disease--global-v.2

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#Surveillance and #control efficacy of the Bergerac, #France, 2025 #chikungunya #outbreak

 

Abstract

The spread of the highly invasive mosquito, Aedes albopictus, across Europe, combined with climate change and human travel and trade, has led to new epidemic threats from mosquito-borne viruses, most significantly dengue and chikungunya, which are increasing in frequency and magnitude. In 2025, mainland France has seen a record number of autochthonous cases and outbreaks of chikungunya, spread across multiple locations, primarily introduced by travellers from the French Overseas Territory of La Réunion which is experiencing severe chikungunya outbreaks. Here, we describe one of the largest French outbreaks and subsequent control measures in the city of Bergerac, Dordogne, which resulted in 102 cases as of 5th November 2025. We apply a climate-driven mathematical model for Ae. albopictus and chikungunya virus transmission to the Bergerac 2025 outbreaks, comparing outputs to case data. The model suggests that the initial control measures in the first four weeks after the discovery of the outbreak, limited in their intervention radius and intensity, had little effect on reducing the number of cases, given the high incidence and the wide geographic extent of viral circulation. However, subsequent more widespread and intense control efforts, combined with likely increased public awareness, substantially reduced case numbers. These findings underscore the need to tailor control measures to intensity and scale of viral circulation combined with effective preventive and proactive arbovirus surveillance. Adulticides combined with public awareness campaigns can be effective for public health protection and are an important part of mitigating against the risk of Aedes-borne arboviruses and the ongoing outbreaks in mainland France.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014184

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Susceptibility of wild and domestic #songbirds to #Usutu virus

Abstract

Usutu virus (USUV) is an emerging mosquito-borne orthoflavivirus that can cause neuroinvasive disease in humans and wild birds. USUV clusters phylogenetically within the Japanese encephalitis virus serocomplex, sharing antigenic and ecological similarity with West Nile virus (WNV). USUV is maintained in an enzootic cycle primarily involving passerine birds and Culex spp. mosquitoes. USUV was first isolated in South Africa in 1959 and has since spread throughout Africa and Europe, causing mortality and disease in several wild bird populations, specifically the Eurasian blackbird (Turdus merula). To understand transmission and pathogenesis of USUV in birds, we sought to develop passerine bird models of infection using wild-caught house finches (Haemorhous mexicanus), wild-caught American robins (Turdus migratorius), domestic canaries (Serinus canaria domestica), and captive-bred zebra finches (Taeniopygia guttata). Birds were inoculated with one or two isolates of USUV and viremia was measured. House finches, American robins, and canaries were susceptible to USUV, with 100% of inoculated birds developing viremia. These avian species reach viremias that have the potential to infect Cx. quinquefasciatus mosquitoes. Clinical disease and histopathological evidence of disease were severe in American robins and moderate to severe in canaries, with limited disease in house finches. However, zebra finches inoculated with one isolate of USUV did not develop detectable viremia. These findings provide additional tools for studying USUV enzootic transmission and pathogenesis in passerine birds.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014213

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#Chikungunya fever: #Brazil is intensifying its response to address health emergency in Dourados (MoH, April 4 '26)

 

{Edited}

The Brazilian government has intensified its response to the emergency situation in Dourados (MS), given the increase in cases of chikungunya, with the mobilization of an interministerial task force that integrates actions in health, assistance, civil defense, and logistical support in the territory. The emergency affects the population of the municipality, with a greater impact on indigenous communities.

As a reinforcement to the response already underway, the Federal Government has guaranteed more than R$ 3.1 million in emergency resources for the municipality. 

Of this total, R$ 1.3 million , authorized by the Ministry of Integration and Regional Development (MIDR) in a decree published this Thursday (2), will be allocated to relief and humanitarian assistance actions, such as direct support to the population and local response structures. 

Also this Thursday, the National Secretariat for Civil Protection and Defense approved a work plan worth R$ 974,100 for restoration actions, including urban cleaning, waste removal and disposal in a licensed sanitary landfill, with resources to be transferred directly to the municipality.

The Ministry of Health has already transferred R$ 855,300 to the municipality to cover the costs of surveillance, assistance, and control actions related to chikungunya in the region.

The federal response has been underway since mid-March, coordinated by the Ministry of Health, which mobilized the National Health System (SUS) Task Force , reinforced healthcare teams, and intensified vector surveillance and control actions across the territory. 

The operation includes actively searching for cases, conducting home visits, eliminating [mosquitoes] breeding sites, and expanding services to the population, with special attention to the most vulnerable areas, including indigenous territories.

The National Health System Task Force has 40 mobilized professionals , with 26 currently working directly, and has already carried out 1,288 clinical consultations , 81 transfers for medium and high complexity care, and 225 home visits . 

The teams operate both in indigenous territories and in the municipalities of Dourados and Itaporã, supporting local management, together with the Mato Grosso do Sul State Health Secretariat, reorganizing care flows, expanding active case finding, and guaranteeing assistance, health education, and psychosocial care.

Fiocruz mobilized the shipment of pain medication, reinforcing its ability to meet local demand due to the epidemic.

To expand response capacity, the Ministry of Health authorized the emergency hiring of 50 Endemic Disease Control Agents (ACEs). Of these, 20 have already been trained and will enter the field this Friday (3), while another 30 will begin training to work from Monday (6).

In the field of vector control, actions were intensified with the mobilization of approximately 95 professionals , including Community Health Agents and Indigenous Sanitation Agents (AISAN). Between March 9 and 16, 4,319 properties were inspected , of which 2,173 received treatment , identifying 1,004 breeding sites of the Aedes aegypti mosquito , mainly in water storage containers, solid waste, and tires.

Actions were also taken to control the spread of insecticide using ultra-low volume (ULV) methods, including three cycles of vehicle-mounted ULV application and backpack spraying in 43 high-traffic areas, such as schools and health units. The volunteer effort to remove breeding sites mobilized approximately 100 people and resulted in the collection of four dump truckloads of waste.

Vector control will be reinforced with support from the Ministry of Defense. Currently, 40 Brazilian Army soldiers and five vehicles are already in the area , expanding the operational capacity of the mosquito control efforts.

The Ministry of Health also sent 1,000 Larvicide Dissemination Stations (LDSs). Of the first 300 units, 150 have already been installed in priority neighborhoods, with expansion planned for other regions of the municipality.

Through Funai (National Indian Foundation), actions are also underway to provide direct support to indigenous communities in Dourados, focusing on food security and access to water. 

The distribution of 6,000 food baskets is planned , in three stages between April and June, in coordination with the Ministry of Social Development (MDS), the National Supply Company (Conab), the Special Secretariat for Indigenous Health (Sesai), and Civil Defense. The expansion of the water supply system in the Jaguapiru and Bororó villages has also been authorized to guarantee access to potable water and improve the sanitary conditions of the indigenous communities.

Epidemiological scenario

The most recent epidemiological surveillance data, referring to April 2nd, indicates that the region has registered 2,812 notifications of chikungunya, with 1,198 confirmed, 430 discarded, and 1,184 still under investigation. The highest concentration of cases is in indigenous villages, where 822 cases were confirmed—68.6% of the total confirmations in the region. 

So far, five deaths have been confirmed in Dourados, all among the indigenous population of the municipality.

To strengthen the coordination of actions, the Ministry of Health established a Situation Room in Brasília on March 25th, with permanent meetings to monitor the situation and integrate decisions between technical teams and managers.

Within the indigenous territory, the work is carried out in a coordinated manner between the Ministries of Health, Indigenous Peoples, Integration and Regional Development, Defense, Social Development, Funai (National Indian Foundation), and the Special Indigenous Health District of Mato Grosso do Sul (DSEI-MS), which has 210 Indigenous Health Agents (AIS) and 150 Indigenous Sanitation Agents (Aisan), in addition to logistical support with 91 pickup trucks, 6 vans, and 1 truck.

The actions also include training for health professionals in the municipal and indigenous networks, aligning clinical protocols for diagnosis and proper management of the disease, as well as health education activities in schools and communities. There are also plans to send prevention messages via WhatsApp to more than 234,000 residents , in Portuguese and with translation into indigenous languages.

The response also includes improving the quality of care, with the implementation of the national chikungunya protocol and training of teams for early identification of severe cases and appropriate clinical management.

Source: 

Link: https://www.gov.br/saude/pt-br/assuntos/noticias/2026/abril/governo-do-brasil-intensifica-resposta-integrada-e-mobiliza-forca-tarefa-para-enfrentar-emergencia-sanitaria-em-dourados-ms-2

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#Culicoides (Diptera: Ceratopogonidae) in Extra-Amazonian #Oropouche #Outbreak Areas of Minas Gerais, #Brazil: #Ecological Insights into Virus Transmission

 

Abstract

Oropouche fever (OF), caused by Oropouche virus (OROV), has expanded beyond its Amazonian range into Minas Gerais (MG), Brazil, raising concern about transmission in extra-Amazonian Atlantic Forest landscapes. Critical gaps persist regarding Culicoides vector communities, anthropophily, and climate-sensitive transmission risk in these newly affected regions. We conducted targeted entomological surveys outbreak-driven by human OF cases, standardized across five MG communities using CDC light traps and Protected Human Attraction (PHA) to characterize Culicoides composition. Females of Culicoides underwent RT-qPCR for OROV (n = 819) and physiological assessment (n = 312). We developed an entomological alert framework that integrates blood-fed abundance, minimum infection rate (MIR) upper confidence bounds, and environmental drivers (i.e., mean temperature, relative humidity and precipitation) via generalized additive mixed models, which explained 68% of the variability in Culicoides abundance and the alert index across communities. We collected 1171 Culicoides individuals representing five species (C. leopoldoi, C. paraensis, C. pusillus, C. foxi, and C. limai). C. leopoldoi (79.1%) and C. paraensis (20.3%) were the predominant species; notably, C. paraensis is recognized as the primary vector of OROV in the Americas. C. paraensis was documented for the first time in all five outbreak areas and dominated PHA captures (90%), suggesting anthropophily. Although no specimens tested OROV-positive (consistent with expected field infection rates of 0.01–1%), MIR upper bounds reached 132/1000 in low-sample settings and humidity and temperature strongly modulated abundance. This operational baseline and alert index transform virologically negative, sparse surveillance data into prioritized targets for intensified sampling and vector control during early, low-prevalence phases, when containment of OROV’s extra-Amazonian spread is still achievable.

Source: 

Link: https://www.mdpi.com/1999-4915/18/3/361

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Association of avian #biodiversity and #WNV circulation in #Culex mosquitoes in Emilia-Romagna, #Italy

 

Abstract

Background

West Nile Virus (WNV) is a zoonotic arbovirus maintained in a transmission cycle between Culex mosquitoes and birds, occasionally spilling over into humans. The impact of avian biodiversity on WNV circulation remains debated, with studies reporting both negative and positive correlations (dilution and amplification effects respectively) across different settings. In Europe, this relationship remains largely unexplored, particularly in regions with high WNV transmission, such as Emilia-Romagna in Northern Italy.

Methods

We explored the association between avian biodiversity and WNV circulation in Culex mosquitoes in Emilia-Romagna using 11 years (2013–2023) of entomological surveillance data paired with two avian data sources. We calculated avian biodiversity indices (Shannon’s, Simpson’s, and Chao2) from observation records from the Farmland Bird Index project and applied linear regression models to assess their relationship with WNV detection frequency. Moreover, we used Bayesian spatiotemporal regression models and gridded weekly avian abundance estimates from the eBird project to analyse the associations between avian species richness indices and WNV transmission risk quantified by vector index (VI) at 68 geolocated mosquito traps across the region.

Results

We observed consistent negative associations between WNV detection frequency in the Culex population and avian biodiversity indices, supporting the dilution effect hypothesis (DEH). We found that non-passerine species richness was negatively associated with VI while passerine species richness showed a positive association after adjusting for covariates and spatial random effects. These findings suggest that passerines may amplify WNV transmission, whereas the presence of non-passerine species is associated with reductions in WNV circulation.

Significance

This study provides the first empirical evidence supporting the DEH for WNV in Europe. These findings have important implications for biodiversity conservation and integrated public health surveillance activities across Europe.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014076

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Serological and viral #prevalence of #Oropouche virus (OROV): A systematic review and meta-analysis from 2000–24 including #human, #animal, and #vector #surveillance studies

 

Abstract

Background

Oropouche virus (OROV) is an emerging arbovirus primarily transmitted by biting midges and is increasingly recognized as a public health threat in Central and South America. With over 11,000 confirmed cases reported in 2024, a ten-fold increase from the previous year, its transmission dynamics and true burden remain poorly understood due to diagnostic challenges and fragmented surveillance systems.

Objective

This systematic review and meta-analysis (SRMA) synthesizes OROV prevalence data in humans and summarizes the available data for vectors and animal hosts sampled between 2000 and 2024 to provide updated estimates and identify key surveillance gaps.

Methods

We systematically searched Web of Science, PubMed, Embase, Medline, and LILACS for OROV seroprevalence and viral prevalence studies in human, insect, and animal populations, published up to September 12, 2024. The review protocol was registered with PROSPERO (CRD42024551000). Studies were extracted in duplicate, and data were meta-analyzed using generalized linear mixed-effects models. Risk of bias was appraised using a modified Joanna Briggs Institute checklist.

Results

We included 71 articles reporting serological or viral prevalence of OROV across nine countries. Between 2000–2024, pooled human seroprevalence among individuals with febrile illness or suspected of Oropouche infection was 12.6% [95% CI 5.3-26.9%] across four South American countries and seroprevalence of 1.1% [95% CI 0.5-2.3%] was observed in asymptomatic groups. Viral prevalence among individuals with febrile illness or suspected of Oropouche infection was 1.5% [0.8-3.0%] across seven South American countries and Haiti. Most studies used convenience sampling and RT-PCR or hemagglutination assays. In vector populations, positive OROV prevalence in Aedes aegypti and Culex quinquefasciatus was reported in two of 18 sources, while 10.0% and 7.5% animal host prevalence was reported in dogs and cattle, respectively. We found high risk of bias in 11.3% of studies in our critical appraisal, with most animal, human, and vector studies falling in the moderate risk of bias range.

Conclusions

Despite rising numbers of OROV reported cases, prevalence estimates remain limited by sparse surveillance and variable methodology. This review highlights the urgent need for standardized serological assays, community-based studies, and expanded surveillance in animal and vector reservoirs. A One Health approach is essential to monitor OROV transmission and inform regional preparedness efforts.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013340

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Rapid #risk #assessment, acute event of potential public health concern: #Chikungunya virus disease, #Global (#WHO, Dec. 29 '25, summary)

 

Overall Risk statement

-- This RRA aims to assess the overall public health risk at the global level posed by the chikungunya virus (CHIKV) transmission during 2025, considering the criteria of potential risk for human health, the risk of geographical spread, and the risk of insufficient control capacities with available resources, and the implications for the 2026 transmission season. 

-- Chikungunya virus (CHIKV) poses a significant and growing global health risk due to large and widespread regional outbreaks in recent years, climate-driven mosquito expansion, lack of specific treatment, and increasing international travel. 

-- While mortality remains relatively low, the CHIKV infection can cause prolonged arthritis with disability as well as  severe illness in some patients. 

-- From 1 January to 10 December 2025, 502 264 CHIKV disease cases including  208 335 confirmed cases, and 186 CHIKV deaths, were reported globally. 

-- While certain WHO Regions are reporting lower case numbers compared to 2024, others are experiencing marked increases, furthermore some countries are seeing an emergence of chikungunya in previously unaffected populations. 

-- This heterogeneity in regional trends complicates the interpretation of the global situation. 

-- The data suggest localized resurgence or emergence in specific geographic areas. 

-- The region of the Americas has reported the highest number of confirmed cases followed by the European region (comprised of cases reported predominantly from French Overseas Departments in the Indian Ocean). 

-- Further, the potential for geographic spread remains substantial given that chikungunya can be introduced into new areas by infected travellers where local transmission may be established in the presence of competent Aedes mosquito, a susceptible population and favorable climatic and ecological conditions.  

-- The global public health risk posed by CHIKV transmission is assessed as moderate, driven by widespread outbreaks across multiple WHO regions during the 2025 season including areas with previously low or no transmission. 

-- The resurgence and emergence of cases in new geographic areas are facilitated by the presence of competent Aedes mosquito vectors, limited population immunity, favorable environmental conditions, and increased human mobility. 

-- The uneven distribution of cases complicates global interpretation, but highlights significant localized transmission. 

-- Control capacities remain challenged by gaps in surveillance, diagnostic access, healthcare infrastructure, and sustainable vector surveillance and control.  

-- Given the ongoing outbreaks reported globally in 2025, the potential for further spread in 2026 cannot be ruled out. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---chikungunya-virus--global-v.1

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A #Market-Based #Sentinel #Surveillance for an Early #Detection of Viral #Outbreaks

 

Abstract

Mexico has experienced recurrent viral epidemics of substantial intensity, including hyperendemic dengue, COVID-19, and recent reports of avian influenza A (H5N1) infections in birds, which pose an ongoing risk of zoonotic transmission. Mexico was also the location for the earliest detection of the pdmH1N1 virus during the 2009 influenza A pandemic. Under a One Health framework, markets represent a unique opportunity for low-cost virus monitoring at the human-animal interface. Under the hypothesis that these represent sentinel sites for an early virus detection, we implemented a pilot surveillance program at the central market of Merida city, Yucatan, Mexico, considered a regional hotspot for multiple and recent viral outbreaks. Longitudinal sampling was carried out over 11 months at 1-to-6-week intervals from April 2022 to February 2023. We used multi-type surveillance in mosquitoes, live poultry, and wastewater. All samples were screened using RT-qPCR. Positive samples for DENV, SARS-CoV-2 and avian influenza A were further sequenced and analysed under a phylogenetic and epidemiological approach. Through our entomological surveillance, we report the earliest detection of DENV-3 III-B3.2 (genotype III American II lineage, considered a major public health concern in Latin America) in Mexico, overlapping with the resurgence of DENV-3 as the predominant serotype driving the 2023 national epidemic, which showed an increased severity. Through wastewater surveillance, we consistently detect SARS-CoV-2 RNA in wastewater samples, coinciding with the two infection waves officially recorded at a city and state level. Finally, cloacal swabs taken from two juvenile birds at the market suggest that avian influenza A viruses circulated in live poultry sold at the market. These findings show that our market-based surveillance framework is effective for an early detection and monitoring of pathogenic viruses in urban settings, and could complement official epidemiological surveillance in low- and middle-income countries to strengthen early-outbreak warning systems.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study was supported by the John Fell OUP Research Grant ATD00390 (M.E.Z and M.U.G.K), the Wellcome Infectious Disease Award ?317324/Z/24/Z (M.G.K, H.P.G and M.E.Z), the Secretaria de Ciencia, Humanidades, Tecnología e Inovación award (SECIHTI, Mexico) through the PRONACES Health grant (PRONAII project number 303002, G.S) and the Ciencia Básica y de Frontera programme (CBF2023-2024-3184, M.G.K), and the UKRI Innovation BSRC/EPSRC/NIHR 971557 grant (A.R.S). M.G.K is funded through a Sanger International Fellowship award. M.E.Z is funded by a UCL Rosetrees Excellence Fellowship UCL2024\2. P.M.D was funded through the doctoral program at ‘Posgrado en Ciencias de la Produccion y de la Salud Animal-UNAM’ through the SECIHTI doctoral scholarship. M.U.G.K. acknowledges funding from The Rockefeller Foundation (PC-2022-POP-005), Health AI Programme from Google.org, the Oxford Martin School Programmes in Pandemic Genomics & Digital Pandemic Preparedness, European Union's Horizon Europe programme projects MOOD (#874850) and E4Warning (#101086640), Wellcome Trust grants 303666/Z/23/Z, 226052/Z/22/Z & 228186/Z/23/Z, the United Kingdom Research and Innovation (#APP8583), the Medical Research Foundation (MRF- RG-ICCH-2022-100069), UK International Development (301542-403), the Bill & Melinda Gates Foundation (INV-063472) and Novo Nordisk Foundation (NNF24OC0094346). B.G is further funded by Wellcome Trust grants 303666/Z/23/Z, 226052/Z/22/Z & 228186/Z/23/Z. The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission or the other funders. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2025.12.22.25342882v1

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