ETIDIOH - NEW

  Abstract Background :  Chikungunya virus (CHIKV) has historically been regarded as a low-fatality infection ; however, growing evidence from diverse study designs demonstrated a substantial mortality burden during large-scale epidemics. In 2025, Réunion Island experienced a major CHIKV outbreak , raising renewed concerns about its fatal impact.  Methods :  We conducted an ecological time-series analysis of all-cause mortality during the 2025 chikungunya epidemic. Expected deaths were estimated using two complementary approaches: (i) a baseline based on age-specific mean mortality rates from the same calendar months in the post-pandemic period and (ii) long-term Poisson regression models using a log-link function and population offset, excluding the COVID-19 pandemic period. Excess mortality was calculated as the difference between observed and expected deaths during periods when observed mortality significantly exceeded the upper bound of the 95% confidence interva...

  Highlights •  Viremia in children with La Crosse Virus infection is transient; viral RNA was detected in only 3.2% of sera •  Detection of La Crosse Virus RNA in respiratory samples is slightly higher at 21.7% and may reflect the temporal distribution of the virus after infection •  NAAT has limited utility in routine diagnosis of La Crosse Virus encephalitis in children but may still be useful in cases with delayed seroconversion Abstract Background La Crosse virus (LACV), a member of family Peribunyaviridae, genus Orthobunyavirus , is the leading cause of neuroinvasive arboviral infection in children in the United States . Diagnosis relies on detecting specific antibodies (IgG or IgM), a 4-fold titer rise or seroconversion, in patients with compatible presentations. NAAT used for LACV detection has largely been limited to mosquito, animal models or postmortem brain tissue. There is a lack of data on the performance of NAATs in clinical specimens from living patie...

  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 d...

  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 ...

  Summary Background The first chikungunya virus (CHIKV) vaccine is now licensed in Brazil, the country that reports the most cases of CHIKV globally ; however, the optimal use of the vaccine remains unclear owing to a poor understanding of CHIKV epidemiology and population immunity . We aimed to combine the distribution of cases and deaths reported since 2014 with seroprevalence studies to inform mathematical models that estimate the underlying rates of infection by state and year, and the underlying patterns of disease and death by age and sex. Methods We quantified the annual CHIKV infection and disease burden between 2014 and 2024 in each of the 27 federative units of Brazil using a mathematical model in a Bayesian framework that integrated serological surveys (n=12) and confirmed CHIKV disease cases (n=488 234) and CHIKV deaths (n=1719) reported between January, 2014, and September, 2024. Using this base, we estimated the potential impact of a vaccine over the period 2025–29 h...

  Situation at a glance Between 20 September and 30 October 2025, a total of 404 confirmed human cases of Rift Valley fever (RVF), including 42 deaths , were reported by national health authorities in two West African countries : Mauritania and Senegal .  RVF is a zoonotic disease , which mainly affects animals, but can also infect humans.  The majority of human infections result from contact with the blood or organs of infected animals, but human infections have also resulted from the bites of infected mosquitoes .  To date, no human-to-human transmission of RVF has been documented.  While RVF often leads to severe illness in animals, its impact in humans varies, ranging from mild flu-like symptoms to severe hemorrhagic fever that can be fatal .  RVF is endemic in both countries, where recurrent outbreaks have been previously reported in both livestock and humans.  The risk of further spread remains high , especially with environmental conditions favo...

  Summary Kyasanur Forest disease is a neglected tick-borne viral haemorrhagic fever endemic to India's Western Ghats , caused by the Kyasanur Forest disease virus , a flavivirus transmitted by Haemaphysalis spinigera ticks . The virus circulates in a sylvatic cycle among monkeys, rodents, shrews, birds, and ixodid ticks , and is transmitted to humans incidentally via tick bites . Since its discovery in 1957 in Karnataka , Kyasanur Forest disease has spread to other Indian states, driven by deforestation , forest fragmentation , and increased human incursion into wildlife habitats . Clinically, the disease manifests in a biphasic pattern , with haemorrhagic and neurotropic presentations . Although a formalin-inactivated vaccine is available , its efficacy is not promising, and no antivirals have been approved to date. Field reports indicate that mortality in monkeys might serve as an early indicator of forthcoming human outbreaks. The transmission dynamics of Kyasanur Forest diseas...

  {Summary} -- During current epidemiological week (from  23 to 29 Oct. 2025) , two new human cases of infection with West Nile Virus have been reported.  -- The cumulative number of confirmed cases this season so far rose to 773 (they were 771 last week), of these:  - 367 were West Nile Neuroinvasive Disease (WNND): 17 in Piedmont, 56 Lombardy, 35 Veneto, 4 Friuli-Venezia Giulia, 1 Liguria, 30 Emilia-Romagna, 11 Tuscany, 1 Marche, 87 Latium, 2 Molise, 83 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 3 Sicily, 28 Sardinia,  - 56 were asymptomatic cases detected in blood donors ,  - 339 were West Nile Fever cases (of which: 1 imported from Kenya , 1  from Egypt and 1 from Maldives),  - 3 asymptomatic cases ,  - 8 unspecified cases.  -- Among confirmed cases, 72 fatalities have been recorded: 7 in Piedmont, 9 Lombardy, 1 Veneto, 2 Emilia-Romagna, 1 Marche, 19 Latium, 29 Campania, 2 Calabria, 1 Sicily, 1 Sardinia.  - The Case-Fatality ...

  Abstract Greece is one of the countries in Europe most affected by West Nile virus (WNV), and since 2010, when the virus caused a large outbreak with 197 human neuroinvasive cases , outbreaks occur almost every year. Mosquito surveillance is an indirect sign of virus circulation; therefore, the purpose of the study was the molecular detection of WNV in 45,988 C. pipiens s.l. mosquitoes collected during 2024 in four Regions of Greece and the genetic characterization of the virus strains. WNV was detected in 41 of 1316 ( 3.12% ) Culex spp. mosquito pools . Next-generation sequencing was applied to the WNV-positive samples that had a high viral load . All WNV sequences belong to Cluster B of the sub-lineage Europe WNV-2A presenting a temporal clustering. The WNV infection rates varied highly across the Regions, regional units and months, being higher in Thessaly and Central Macedonia Regions , especially in July and September. All mosquito pools were also tested for Usutu virus (USU...

  {Summary} -- New human cases of West Nile Virus infection continue to be reported albeit with reduced intensity.  -- During current epidemiological week (from  9 to 15 October 2025)  26 new confirmed cases have been reported.  -- The total number of cases so far is 767 (they were 740 last week), of these:  - 366 were West Nile Neuroinvasive Disease (WNND): 17 in Piedmont, 56 Lombardy, 34 Veneto, 4 Friuli-Venezia Giulia, 1 Liguria, 32 Emilia-Romagna, 10 Tuscany, 1 Marche, 86 Latium, 2 Molise, 83 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 3 Sicily, 28 Sardinia,  - 57 were asymptomatic cases among blood donors ,  - 333 were West Nile Fever cases (of which 1 imported from Kenya, 1 from Egypt and 1 from Maldive),  - 3 asymptomatic cases,  - eight unspecified cases.  -- Among confirmed cases, 69 fatalities  have been reported: 7 in Piedmont, 9 Lombardy, 2 Emilia-Romagna, 18 Latium, 29 Campania, 2 Calabria, 1 Sicily, 1 Sardinia....

  ALBANY, N.Y. (October 14, 2025) — The New York State Department of Health today announced that a case of locally acquired chikungunya has been confirmed in New York State . Laboratory testing at the Department's Wadsworth Center confirmed the case in Nassau County on Long Island . This marks the first locally acquired case of chikungunya reported in New York State . No locally acquired cases have been reported in the U.S. states and territories since 2019. An investigation suggests that the individual likely contracted the virus following a bite from an infected mosquito . While the case is classified as locally acquired based on current information, the precise source of exposure is not known. The Aedes albopictus mosquito , known to transmit chikungunya, is present in parts of downstate New York. Local transmission can occur when an A. albopictus mosquito bites an infected traveler, becomes infected and bites another person. The disease cannot be spread directly from one person...

{Summary} -- During current epidemiological week , a rise in the West Nile Virus human cases has been observed although with reduced intensity compared most recent weeks.  -- Twenty-two new confirmed human cases have been reported during surveillance week from 2 to 8 October 2025.  -- The cumulative number of cases rose to 740  (they were 718 last week), of these:  - 354 were West Nile Neuroinvasive Disease (WNND): 16 in Piedmont, 53 Lombardy, 33 Veneto, 4 Friuli-Venezia Giulia, 1 Liguria, 30 Emilia-Romagna, 11 Tuscany, 1 Marche, 84 Latium, 2 Molise, 81 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 3 Sicily, 26 Sardinia, - 57 were asymptomatic cases in blood donors ,  - 318 were West Nile Fever cases , of which 1 imported from Kenya , 1 from Egypt and 1 from Maldives ,  - 4 asymptomatic cases,  - 7 unspecified cases.  -- Among confirmed cases there were 68 fatalities : 7 in Piedmont, 9 Lombardy, 2 Emilia-Romagna, 18 Latium, 28 Campania, 2 Cal...

  Abstract In July 2025, China witnessed its most significant chikungunya virus (CHIKV) outbreak since 2010. As of August 1, with over 6,000 cases reported in Foshan city, Guangdong Province . Although the clinical manifestations have been relatively mild , the rapid transmission within communities warrants our attention. In this context, we emphasize our current knowledge and the necessary actions to take. Specifically, we identify critical gaps in CHIKV control efforts and assess the effectiveness of current measures. These include vector management strategies , viral genomic surveillance , the deployment of newly approved vaccines , and the development of antiviral agents . Overall, to effectively control the epidemic of CHIKV, we require a comprehensive and multifaceted strategy for its prevention and management. Source: PLoS Pathogens,  https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1013556 ____

  Situation at a glance In 2025, a resurgence of chikungunya virus (CHIKV) disease was noted in a number of countries , including some that had not reported substantial case numbers in recent years.  Between 1 January and 30 September 2025, a total of 445 271 suspected and confirmed CHIKV disease cases and 155 deaths were reported globally from 40 countries , including autochthonous and travel imported cases.  Some WHO Regions are experiencing significant increases in case numbers compared to 2024, although others are currently reporting lower case numbers.  This uneven distribution of cases across regions makes it challenging to characterize the situation as a global rise, however, given the ongoing outbreaks reported globally in 2025, the potential for further spread remains significant .  CHIKV disease can be introduced into new areas by infected travelers and local transmission may be established if there is the presence of Aedes mosquito and a susceptible p...

  {Summary} -- During current epidemiological week (from  25 September to 1rst October 2025),  38 new confirmed human infection with West Nile Virus have been reported.  -- Since the beginning of the epidemic season, 718 confirmed cases have been recorded in Italy (they were 680 in the last bulletin), of these:  - 341 were West Nile Neuroinvasive Disease (WNND): 15 in Piedmont, 51 Lombardy, 30 Veneto, 4 Friuli-Venezia Giulia, 1 Liguria, 27 Emilia-Romagna, 11 Tuscany, 1 Marche, 84 Latium, 2 Molise, 79 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 2 Sicily, 25 Sardinia,  - 57 were asymptomatic cases in blood donors ,  - 309 were West Nile Fever cases (1 imported from Kenya , 1 Egypt , and one Maldives ),  - 4 asymptomatic cases,  - 7 unspecified cases.  -- Among confirmed cases , there have been 49 fatalities : 7 in Piedmont, 5 Lombardy, 2 Emilia-Romagna, 18 Latium, 14 Campania, 2 Calabria, 1 Sardinia.  - The Case-Fatality Rate in WNN...

  {Summary} -- During current surveillance week (from 18 to 24 Sept. '25), 33 new confirmed human cases of West Nile Virus have been detected.  -- Since the beginning of the epidemic season , there have been 680 cases in total , (they were 647 last week); of these:  - 321 were West Nile Neuroinvasive Disease (WNND): 15 in Piedmont, 44 Lombardy, 27 Veneto, 2 Friuli-Venezia Giulia, 1 Liguria, 25 Emilia-Romagna, 8 Tuscany, 1 Marche, 83 Latium, 2 Molise, 79 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 1 Sicily, 24 Sardinia),  - 54 were asymptomatic cases in blood donors ,  - 296 were West Nile Fever cases (1 imported from Kenya , 1 Egypt and 1 Maldives ),  - 3 asymptomatic cases,   - 6 unspecified cases.  --  Among confirmed cases , there were 48 deaths : 7 in Piedmont, 5 Lombardy, 2 Emilia-Romagna, 17 Latium, 14 Campania, 2 Calabria, 1 Sardinia.  - The Case-Fatality Rate among WNND cases was 14.9% (it was 20% in 2018 and 14% in 2024)....

  Highlights •  Most vector-borne viruses like alphaviruses are not included in routine diagnostics •  Lack of testing results in misdiagnoses and underdetection •  A new multiplexed real-time PCR assay detects all human pathogenic alphaviruses •  The new multiplex assay is more sensitive than available tests and highly specific •  The multiplex test can be applied broadly for diagnostics and molecular surveillance Abstract Background Knowledge of epidemiology, pathogenesis, and public health burden is scarce for many arthropod-borne viruses (arboviruses). Insufficient knowledge is partly due to lack of exhaustive laboratory diagnostics due to resource limitations . Among arboviruses , arthritogenic and encephalitogenic alphaviruses are globally widespread, can cause severe disease, and can co-occur regionally. Objectives We developed and validated a multiplexed real-time reverse transcription-PCR assay for the detection of all alphaviruses commonly causing...

  {Summary} -- During current epidemiological week ( 11– 17 September 2025),  65 new confirmed human cases of infection with West Nile Virus have been reported.  -- The total number of confirmed cases , since the beginning of the epidemic season, has thus risen to 647 (it was 582 last week), of these:  - 300 were West Nile Neuroinvasive Disease (WNND): 15 in Piedmont, 39 Lombardy, 24 Veneto, 2 Friuli-Venezia Giulia, 1 Liguria, 23 Emilia-Romagna, 5 Tuscany, 83 Latium, 2 Molise, 77 Campania, 2 Apulia, 2 Basilicata, 5 Calabria, 1 Sicily, 19 Sardinia,  - 54 were asymptomatic cases detected among blood donors ,  - 284 were West Nile Fever cases (one imported from Kenya),  - 3 asymptomatic cases and  - 6 unspecified casese.  -- Among confirmed cases, there were 47 death cases : 7 in Piedmont, 5 Lombardy, 1 Emilia-Romagna, 16 Latium, 15 Campania, 2 Calabria, 1 Sardinia.  - The Case-Fatality Rate in WNND cases was 15.8% (it was 20% in 2018 and...

{Summary} -- During current epidemiological week (4 to 10 September), eighty new confirmed human cases of West Nile Virus infection have been reported in Italy. -- Since the beginning of the epidemic season , there have been a total of 582 confirmed cases (they were 502 last week), of these:  - 260 were West Nile Neuroinvasive Disease (WNND): 14 in Piedmont, 24 Lombardy, 22 Veneto, 1 Friuli-Venezia Giulia, 1 Liguria, 20 Emilia-Romagna, 3 Tuscany, 77 Latium, 2 Molise, 74 Campania, 1 Apulia, 2 Basilicata, 5 Calabria, 1 Sicily, 13 Sardinia,  - 48 asymptomatic cases among blood donors ,  - 262 cases of West Nile Fever (1 imported from Kenya ),  - 4 asymptomatic cases,  - 8 unspecified cases.  -- A total of 39 fatal cases have been reported so far this season: 5 in Piedmont, 2 Lombardy, 1 Emilia-Romagna, 15 Latium, 14 Campania, 2 Calabria.  - The Case-Fatality Rate among WNND cases is thus far at 15% (during 2018 season it was 20%, in 2024 14%).  -- Du...

  Abstract Background :  West Nile (WNV), Usutu (USUV), and Sindbis (SINV) virus were initially detected in the African region , and subsequently across temperate regions where they were absent. Wild birds are primary reservoirs for these arboviruses and are considered major contributors to their global spread through seasonal migration . To understand the transmission dynamics of arboviruses in wild birds and the potential of migratory birds to spread the viruses at an intercontinental scale , we investigated arboviral infections and exposures in African resident and Palearctic migratory birds at wintering locations in Nigeria.  Methodology/Principal Findings :  Oropharyngeal- and cloacal swabs , feathers and blood were collected from resident and migratory birds at two wintering locations ( Amurum and Ngel-Nyaki Forest Reserves ). Swabs and feathers were tested using RT-PCR for WNV, USUV and SINV, and blood with ELISA and FRNT90 or PRNT80 for antibodies. 573 birds ...