#Hantavirus #cluster linked to cruise #ship travel, Multi-country (#WHO D.O.N., May 9 '26)

 

8 May 2026

Situation at a glance

-- On 2 May 2026, a cluster of passengers with severe respiratory illness aboard a cruise ship was reported to the World Health Organization (WHO). 

-- At that time, according to the ship operator, 147 passengers and crew were onboard, and 34 passengers and crew had previously disembarked. 

-- Since the last Disease Outbreak News published on 4 May, three of the suspected cases were confirmed, and one additional confirmed case was reported. 

-- As of 8 May, a total of eight cases, including three deaths (case fatality ratio 38%), have been reported. 

-- Six cases have been laboratory-confirmed as hantavirus infections, with all identified as Andes virus (ANDV). 

-- Through the International Health Regulations (2005) (IHR) channel, National IHR Focal Points (NFPs) have all been informed and are supporting international contact tracing. 

-- WHO assesses the risk to the global population posed by this event as low and will continue to monitor the epidemiological situation and update the risk assessment. 

-- The risk for passengers and crew on the ship is considered moderate.

Description of the situation

-- On 2 May 2026, WHO received notification from the National IHR Focal Point of the United Kingdom of Great Britain and Northern Ireland (hereafter referred to as the United Kingdom) regarding a cluster of severe acute respiratory illness, including two deaths and one critically ill passenger, aboard a Dutch-flagged cruise ship.

-- Since the last Disease Outbreak News was published on 4 May, three of the suspected cases were confirmed, and one additional confirmed case was reported. 

-- As of 8 May, a total of eight cases (six confirmed and two probable cases), including three deaths (two confirmed and one probable), case fatality ratio 38%, have been reported. 

-- All six laboratory-confirmed cases were identified as Andes virus through virus specific polymerase chain reaction (PCR) or sequencing.

-- Two medical evacuation flights, from Cabo Verde, carrying two symptomatic confirmed patients and one previously suspected case landed in the Netherlands on 6 and 7 May. 

-- As of 8 May, four patients are currently hospitalised, one in intensive care in Johannesburg, South Africa, two in different hospitals in the Netherlands and the other in Zurich, Switzerland. 

-- The previously suspected case was transferred directly to Germany, where she was tested, and both PCR and serology tests were negative for Andes virus, she is therefore no longer considered to be a case.

-- Contact tracing of passengers who disembarked in St Helena is ongoing; passengers have been contacted and advised to self-monitor for symptoms. 

-- Additionally, passengers who travelled on the same flight from St Helena to South Africa with one of the cases who was subsequently confirmed, have been contacted.

-- On 6 May, the ship left Cabo Verde, heading to the Canary Islands, Spain where disembarkation is planned.

-- Further investigations into the potential exposure of the first case and the source of the outbreak are ongoing in collaboration with authorities in Argentina and Chile. 

-- The outbreak is being managed through a coordinated international response, including in-depth epidemiological investigations, case isolation and clinical management, medical evacuations, laboratory testing and international contact tracing and monitoring.

Summary of confirmed and probable cases:

-- Case 1: 

- An adult male who boarded the ship on 1 April, after more than three months of travel in Argentina, Chile, and Uruguay. 

- Developed symptoms on 6 April and died onboard on 11 April. 

- No microbiological tests were performed. 

- He is considered a probable case.

-- Case 2: 

- An adult female, who was a close contact of case 1, who travelled and boarded the ship with him, went ashore at Saint Helena on 24 April with gastrointestinal symptoms. 

- She subsequently deteriorated on a flight to Johannesburg, South Africa, on 25 April. 

- She died on 26 April in a Johannesburg clinic. 

- On 4 May, she was subsequently confirmed by PCR testing with hantavirus infection.

-- Case 3: 

- An adult male who developed symptoms on 24 April. 

- He was disembarked and medically evacuated from Ascension Island on 27 April and is currently hospitalised in an Intensive Care Unit (ICU) in Johannesburg, South Africa. 

- PCR testing confirmed hantavirus infection on 2 May, and Andes virus was confirmed through sequencing.

-- Case 4: 

- An adult female, with onset of symptoms (fever and general malaise) on 28 April, later presenting with pneumonia, died on 2 May. 

- A post-mortem sample was collected and sent to the Netherlands with the evacuated patients, where it was confirmed to be Andes virus.

-- Case 5: 

- An adult male, working as the ship doctor, reported onset of symptoms on 30 April, including fever, fatigue, muscle pain, and mild respiratory symptoms. 

- His samples confirmed PCR positivity for Andes virus on 6 May. 

- The case was medically evacuated to the Netherlands on 6 May and is currently stable in isolation.

-- Case 6: 

- An adult male, working as a ship guide. 

- Onset of symptoms was reported on 27 April with mild respiratory and gastrointestinal symptoms. 

- Laboratory samples confirmed PCR positivity for Andes virus on 6 May. 

- The case was medically evacuated to the Netherlands on 7 May and is currently stable in isolation.

-- Case 7: 

- An adult male, who disembarked in St Helena on 22 April and flew back to Switzerland on 27-28 April, through South Africa and Qatar. 

- He started experiencing symptoms on 1 May after arrival in Switzerland, where he immediately self-isolated and reported to local public health authorities. 

- He is currently hospitalised and in isolation in Switzerland. 

- His samples confirmed PCR positivity for Andes virus on 5 May.[1]

-- Case 8: 

- An adult male, who disembarked in Tristan da Cunha on 14 April. 

- Onset of symptoms was reported on 28 April with diarrhoea and two days later with fever. 

- He is currently stable and in isolation. 

- He is currently a probable case until laboratory confirmation.

-- One case previously reported as suspected has now been reclassified as a non-case after testing negative for Andes virus through PCR and serology. 

- Nevetheless, monitoring continues until the end of their incubation period from last exposure.  

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Operational outbreak case definitions

-- Suspected case: 

- anyone who shared or visited a conveyance where there has been a confirmed or probable ANDV case 

* AND * 

- with acute (or history of) symptoms compatible with ANDV infection, including fever (38°C or above),  myalgia, chills, acute gastrointestinal (e.g. nausea, vomiting, diarrhoea, abdominal pain) or acute respiratory (e.g. cough, shortness of breath, chest pain, difficulty breathing) symptoms.

-- Probable case: 

- a person with signs and symptoms of a suspected case that has been evaluated by a health professional 

* AND * 

- a known epidemiological link with a confirmed or probable ANDV case 

* AND * 

- for which laboratory results have not been conducted.

-- Confirmed case: 

-- a person with laboratory confirmation of ANDV through RT-PCR or serology testing.

-- Non-case*: 

- a suspected or probable case who tests negative for ANDV by RT-PCR or serology.

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{*} Non-cases who develop symptoms compatible with the suspected case definition after a negative test and within the maximum incubation period after last exposure to a probable or confirmed case should be retested and reclassified as appropriate. 

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-- Based on currently available information, the working hypothesis is that case 1 most probably acquired the infection prior to boarding through environmental exposure during activities he conducted in Argentina and Chile. 

-- Investigations are ongoing to assess the full itinerary of his activities and possible exposure factors. 

-- Current evidence points to subsequent human-to-human transmission onboard (Figure 1), given documented epidemiological links of some of the subsequent cases with case 1 during his illness, and the timing of their symptom onset, which clusters around the most likely incubation periods previously documented for ANDV. 

-- However, ongoing epidemiological and sequencing investigations will help better understand the epidemiological links between cases and their most likely exposure.

Epidemiology

-- Hantavirus cardiopulmonary syndrome (HCPS), also known as hantavirus pulmonary syndrome (HPS), is a zoonotic, viral respiratory disease caused by hantaviruses of the genus Orthohantavirus, family Hantaviridae, order Bunyavirales. 

-- More than 20 viral species have been identified within this genus. 

-- In the Americas, Sin Nombre virus is the predominant cause of HPS in North America, while Orthohantavirus andesense is responsible for most cases in South America.

-- Hantaviruses found in Europe and Asia are known to cause haemorrhagic fever with renal syndrome (HFRS), which primarily affects the kidneys and blood vessels. 

-- Human-to-human transmission has not been documented in this part of the world.

-- Human Hantavirus infection is primarily acquired through contact with the urine, faeces, or saliva of infected rodents or by touching contaminated surfaces. 

-- Exposure typically occurs during activities such as cleaning buildings with rodent infestations, though it may also occur during routine activities in heavily infested areas. 

-- Human cases are most commonly reported in rural settings, such as forests, fields, and farms, where rodents are present, and opportunities for exposure are greater. 

-- HPS is characterized by headache, dizziness, chills, fever, myalgia, and gastrointestinal symptoms, such as nausea, vomiting, diarrhoea, and abdominal pain, followed by sudden onset of respiratory distress and hypotension. 

-- Symptoms of HPS typically occur from 1-6 weeks after initial exposure to the virus. However, symptoms may appear as early as one week and as late as eight weeks following exposure.

-- Hantavirus infections are relatively uncommon globally.  

-- In 2025, in the Region of the Americas, eight countries reported 229 cases and 59 deaths with a CFR of 25.7%.[2] 

-- In the European Region, 1885 hantavirus infections were reported in 2023 (0.4 per 100 000), marking the lowest rate observed between 2019 and 2023.[3] 

-- In East Asia, particularly China and the Republic of Korea, hantavirus haemorrhagic fever with renal syndrome (HFRS) continues to account for many thousands of cases annually, although incidence has declined in recent decades.

-- Hantavirus infections are associated with a case fatality rate of <1–15% in Asia and Europe and up to 50% in the Americas. 

-- While there are no licensed treatment nor vaccines for hantavirus infections, early supportive care and immediate referral to a facility with a complete ICU can improve survival.

-- Environmental and ecological factors affecting rodent populations can influence disease trends seasonally. Since hantavirus reservoirs are sylvatic rodents, transmission can occur when people come into contact with rodent habitats.

-- Although uncommon, limited human‑to‑human transmission of HPS due to Andes virus has been reported in community settings involving close and prolonged contact. 

-- Secondary infections among healthcare workers have been previously documented in healthcare facilities, though remain rare. 

-- Secondary transmission appears most likely during the early phase of illness, when the virus is more transmissible.[4] 

-- Currently, little evidence is available due to the scarcity of hantavirus outbreak related to human-to-human transmission.

Public health response

-- Authorities from States Parties involved in the management of the event to date –  Argentina, Cabo Verde, Chile, Germany, the Netherlands, South Africa, Spain, Switzerland, and the United Kingdom –  WHO, and partners have initiated coordinated response measures including:

-- Ongoing engagement between WHO and the National IHR Focal Points of Argentina, Cabo Verde, Chile, Germany, the Netherlands, South Africa, Spain, Switzerland and the United Kingdom, to ensure timely information sharing and coordination of response actions. International contact tracing involving partners is ongoing.

-- Passengers onboard have been advised to practice physical distancing and remain in their cabins where possible, while on the cruise ship.

-- One expert from WHO and one from the European Centre for Disease Prevention and Control (ECDC) are on board the ship for the provision of public health advice to passengers during the journey.

-- Epidemiological investigations are underway to determine the source of exposure.

-- WHO shared information about the event,  technical guidance on the management of hantavirus on board the ship, a technical note for the disembarkation and onward management of passengers and crew, information on the management of contacts of Andes virus cases, its rapid risk assessment of the associated public health risk, case investigation forms and details on primers and probes for Andes virus detection with National IHR Focal Points globally through its secure Event Information Site for IHR NFPs to support States Parties in responding to the event.

-- The National IHR Focal Points of countries with cases have shared passenger and crew lists with the National IHR Focal Points of the respective countries, according to each person’s nationality. IHR NFP international contact tracing efforts are ongoing for conveyances.

-- The National IHR Focal Point of Argentina requested information, which has been provided, on the first two cases to reconstruct their travel itinerary in the Southern Cone subregion of the Americas and assess any potential exposure to hantavirus.

-- In line with the Working Arrangement between the WHO Emergency Medical Team (EMT) Secretariat and the EU Emergency Response Coordination Centre (ERCC), the EMT Secretariat has launched formal discussions to support the clinical management and medical evacuation of symptomatic passengers. EU Health Task Force (EUHTF) has also been activated for support.

-- Logistic support has been provided, including sample collection items. WHO supported the shipment of samples to the Institut Pasteur de Dakar, Senegal.

-- Laboratory testing and confirmation of hantavirus infection have been conducted at the National Institute for Communicable Diseases (NICD) of South Africa. Identification of Andes virus was performed through genomic sequencing at NICD and virus-specific PCR at Geneva University Hospitals, Switzerland.

-- WHO supported collaboration across laboratories to ensure further timely testing, involving laboratories in Senegal, the United Kingdom, the Netherlands and Argentina. Further testing is currently on-going including serology, sequencing and metagenomics.

-- WHO has developed guidance documents in support of countries affected by the event, including covering management of the event on the ship, investigation of cases, disembarkation and management of returning passengers and crew members.

-- Risk communication coordination and support are being provided to ensure sharing of regular, timely and evidence-based information. WHO has activated three-level coordination and is supporting national authorities in implementing risk-based, evidence-informed public health measures in accordance with the provisions of the IHR and related WHO technical guidance documents.

WHO risk assessment

-- WHO currently assesses the public health risk related to the cruise ship as moderate, and at the Global level as low for the following reasons:

- The disease can have a high case fatality ratio, reaching 40-50%, particularly among elderly individuals and those with co-morbidities. 

- The average age of passengers on board the ship is 65 years old.

- Andes virus has demonstrated limited human-to-human transmission in previous outbreaks, typically occurring among close contacts and within household settings, generally requiring prolonged close exposure. 

- Transmission can usually be contained through early detection, isolation of cases, clinical management, and contact tracing. 

- However, the ship environment presents an increased risk due to close living quarters, shared indoor spaces, prolonged exposure, and frequent interpersonal interactions, all of which may facilitate transmission.

- Investigations on the travel history and potential exposures of the first case in the Southern Cone subregion of the Americas are ongoing and suggest possible exposure to rodents during bird watching activities. 

- Viral sequencing analyses are also ongoing and will compare the ANDV strain associated with this outbreak with strains circulating in Argentina, Chile and Uruguay, where the disease is enzootic.

- Additional cases may occur among individuals exposed before implementation of containment measures. However, the current response, including rapid isolation of any new suspect cases and the monitoring of contacts, is expected to limit the risk of further spread.

- As there is no specific antiviral treatment for HPS, suspected cases require prompt transfer to an adequately equipped emergency department or intensive care unit, where available, for close monitoring and supportive management to improve chances of recovery. 

- Consequently, rapid transfer to a mainland healthcare facility is required, which may be challenging under the current conditions.

- More detailed epidemiological, clinical and laboratory investigations are required to inform further iterations of this risk assessment. 

WHO advice

-- WHO advises that States Parties involved in this event continue public health coordination and management efforts on board conveyances and in countries where cases and/or contacts are present or will be returning to.

-- This includes contact tracing and monitoring detection, investigation, reporting of suspected cases, laboratory testing of suspected cases, case management, infection prevention and control measures, and clear and transparent communication to affected individuals and the general public.

-- In the context of the current outbreak, people on board the affected ship and flights should practice frequent hand hygiene, monitor any early symptoms, including headache, dizziness, chills, fever, myalgia, and gastrointestinal problems, such as nausea, vomiting, diarrhoea, and abdominal pain, for 42 days after last potential exposure. 

-- Should any early symptoms or sudden onset of respiratory distress occur, people should immediately inform health authorities and self-isolate until medical evaluation is conducted. If respiratory symptoms are present, people should practice respiratory etiquette and wear a medical mask.

-- A precautionary approach should be applied to contact identification, classification, tracing and follow-up, particularly for persons exposed on board of the ship or during travel. 

-- Contacts should be classified according to exposure risk, considering the intensity and duration of exposure, proximity to the case, exposure to enclosed or shared spaces, and use of personal protective equipment.

-- High-risk contacts may include cabin mates, intimate partners, persons with prolonged close indoor exposure, healthcare workers with unprotected exposure, and individuals handling contaminated materials or body fluids without appropriate personal protective equipment. 

-- High-risk contacts should undergo active symptom monitoring by a local public health authority for 42 days following the last exposure, while low-risk contacts should undertake passive self-monitoring and seek medical evaluation if symptoms occur. 

-- Contact investigations should use available information sources, including interviews, passenger manifests, seating arrangements and activity logs, to improve completeness of contact identification. 

-- Current evidence does not support usefulness of routine laboratory testing or quarantine of asymptomatic contacts.

-- Early recognition of suspected cases, prompt isolation, and consistent adherence to recommended infection prevention and control measures remain essential to protect healthcare personnel, other passengers and crew members.

-- In healthcare environments, standard precautions* should be applied for all patients, including hand hygiene, environmental cleaning and waste management. 

-- In addition to standard precautions, transmission-based precautions should be implemented for management of suspect or confirmed cases. For aerosol-generating procedures, airborne precautions should be used. [5]

-- When HPS is suspected, patients should be promptly transferred to an emergency department or intensive care unit for close monitoring and supportive management.

-- Initial management should include supportive care with antipyretics and analgesics as needed. 

-- For confirmed hantavirus, antibiotics are not routinely indicated. However, before a definitive diagnosis is established (and bacterial infection is a diagnostic possibility), or if superadded bacterial infection is suspected, empiric broad-spectrum antibiotics may be appropriate. 

-- Clinical management relies primarily on careful fluid administration, hemodynamic monitoring, and respiratory support. 

-- Given the rapid progression of HCPS, close monitoring and early transfer to ICU are critical for more severe cases. 

-- Mechanical ventilation, meticulous volume control, and vasopressors may be required. 

-- For severe cardiopulmonary insufficiency, extracorporeal mechanical oxygenation may be lifesaving. In severe cases of renal dysfunction, dialysis may be required.

-- Although ribavirin has shown efficacy against hantavirus haemorrhagic fever with renal syndrome, it has not demonstrated effectiveness for HCPS and is not licensed for either treatment or prophylaxis of hantavirus pulmonary syndrome.  

-- At present, there is no specific antiviral treatment approved for HCPS; a number of existing drugs have antiviral activity in laboratory studies but not yet demonstrated in human disease.

-- Public health awareness efforts should focus on improving early detection, ensuring timely treatment, and reducing exposure risks. Preventive measures should address occupational and ecotourism-related exposures, emphasize infection prevention and control measures, and include rodent control strategies. Most routine tourism activities carry little or no risk of exposure to rodents or their excreta.

-- Risk communication and community engagement (RCCE) interventions should prioritize transparent, timely, and culturally appropriate communications to raise awareness of hantavirus transmission risks—particularly. 

-- RCCE strategies should support coordinated, timely and aligned evidence based information to ensure concerned people receive clear, consistent and actionable information and explanations of the public health measures. Operational measures should integrate RCCE activities through the whole event. The implementation of integrated environmental management strategies aimed at reducing rodent populations is also recommended.

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{*} Standard precautions refer to a set of practices that are applied to the care of patients, regardless of the state of infection (suspicion or confirmation), in any place where health services are provided. These practices aim to protect both healthcare professionals and patients and include hand hygiene, use of personal protective equipment, respiratory hygiene and cough etiquette, safe handling of sharps materials, safe injection practices, use of sterile instruments and equipment and cleaning of hospital environments and the environment. Adapted from “Standard precautions for the prevention and control of infections: aide-memoire”- WHO, 2022.  Available at https://www.who.int/publications/i/item/WHO-UHL-IHS-IPC-2022.1}  

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-- WHO advises against the application of any travel or trade restrictions based on the current information available on this event. 

Further information

-- World Health Organization. Hantavirus fact sheet. https://www.who.int/news-room/fact-sheets/detail/hantavirus 

-- World Health Organization.WHO’s response to hantavirus cases linked to a cruise ship. https://www.who.int/news/item/07-05-2026-who-s-response-to-hantavirus-cases-linked-to-a-cruise-ship 

-- World Health Organization. Handbook for management of public health events on board ships https://www.who.int/publications/i/item/9789241549462

-- World Health Organization. Guide to Ship Sanitation, 3rd edition https://www.who.int/publications/i/item/9789241546690

-- World Health Organization. Vector surveillance and control at ports, airports and ground crossings https://www.who.int/publications/i/item/9789241549592

-- World Health Organization. Hantavirus outbreak toolbox. https://www.who.int/emergencies/outbreak-toolkit/disease-outbreak-toolboxes/hantavirus-outbreak-toolbox

-- World Health Organization (4 May 2026). Disease Outbreak News. Hantavirus cluster linked to cruise ship travel- Multi-country. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON599 

-- World Health Organization. A decision framework for effective, equitable and context-specific public health and social measures during public health emergencies: decision navigator: https://iris.who.int/server/api/core/bitstreams/ceaf4aa7-00c8-4681-9c35-965e231a3706/content

-- Pan American Health Organization / World Health Organization. PAHO supports the international response to hantavirus pulmonary syndrome cases linked to a cruise ship in the Atlantic. https://www.paho.org/en/news/7-5-2026-paho-supports-international-response-hantavirus-pulmonary-syndrome-cases-linked 

-- Epidemiological Alert Hantavirus Pulmonary Syndrome (HPS). https://www.paho.org/en/documents/epidemiological-alert-hantavirus-pulmonary-syndrome-americas-region-19-december-2025  

-- Hantavirus in the Americas: Guidelines for diagnosis, treatment, prevention and control. Available at: https://iris.paho.org/handle/10665.2/40176

-- Hantavirus Prevention, CDC: https://www.cdc.gov/hantavirus/prevention/?CDC_AAref_Val=https://www.cdc.gov/hantavirus/hps/prevention.html

-- Martínez Valeria, Paola N, et al.. (2020). “Super-Spreaders” and Person-to-Person Transmission of Andes Virus in Argentina. New England Journal of Medicine. 383. 2230-2241. 10.1056/NEJMoa2009040.

-- US CDC. How to Clean Up After Rodents: https://www.cdc.gov/healthy-pets/rodent-control/clean-up.html

-- Hantavirus, Washington State Department of Heath, https://doh.wa.gov/sites/default/files/2025-08/420-056-Guideline-Hantavirus.pdf

-- Hantavirus Infection, MDS Manual, professional version: https://www.msdmanuals.com/professional/infectious-diseases/arboviruses-arenaviridae-and-filoviridae/hantavirus-infection

-- Handbook for management of public health events on board ships. https://www.who.int/publications/i/item/9789241549462

-- Hantavirus pulmonary syndrome, https://www.mayoclinic.org/diseases-conditions/hantavirus-pulmonary-syndrome/symptoms-causes/syc-20351838

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[1] Complete sequence of Orthohantavirus andesense virus: Swiss resident 2026. https://virological.org/t/complete-sequence-of-orthohantavirus-andesense-virus-swiss-resident-2026/1023

[2] Pan American Health Organization / World Health Organization (PAHO/WHO). Epidemiological Alert Hantavirus Pulmonary Syndrome (HPS). https://www.paho.org/en/documents/epidemiological-alert-hantavirus-pulmonary-syndrome-americas-region-19-december-2025  

[3] Hantavirus infection - Annual Epidemiological Report for 2023. https://www.ecdc.europa.eu/en/publications-data/hantavirus-infection-annual-epidemiological-report-2023

[4] WHO fact sheet. https://www.who.int/news-room/fact-sheets/detail/hantavirus

[5] Standard precautions for the prevention and control of infections: aide-memoire. https://www.who.int/publications/i/item/WHO-UHL-IHS-IPC-2022.1 

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Citable reference: World Health Organization (8 May 2026). Disease Outbreak News. Hantavirus cluster linked to cruise ship travel, Multi-country. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON600

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON600

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Immunopathogenic insights into members of the class #Bunyaviricetes: a comparative #review of emerging #zoonotic #threats

 

Abstract

The class Bunyaviricetes encompasses a diverse group of vector- and rodent-borne viruses, many of which are major human pathogens causing severe and often lethal diseases worldwide. These include Lassa fever virus (Arenaviridae), hantaviruses such as Hantaan and Andes viruses (Hantaviridae), Crimean-Congo hemorrhagic fever virus (Nairoviridae), La Crosse and Oropouche viruses (Peribunyaviridae), and Rift Valley fever, severe fever with thrombocytopenia syndrome, and Toscana viruses (Phenuiviridae). Clinical syndromes range from hemorrhagic fever with multiorgan failure, vascular leak, and shock to acute encephalitis and severe respiratory distress. Despite their public health impact, safe and effective vaccines or targeted therapeutics are lacking for most bunyaviricetes diseases, leaving supportive care as the primary intervention. This review provides a comparative analysis of the immunopathogenesis of major human-pathogenic bunyaviricetes, highlighting shared and virus-specific strategies for innate immune evasion, cytokine modulation, and host cell targeting. Severe disease often arises from viral interference with key sensing pathways, such as RIG-I/MDA5 and downstream IRF and NF-κB signaling, which either suppresses interferon responses or leads to dysregulated inflammation. By integrating molecular, immunological, and clinical insights, we outline how these immune-virus interactions shape disease trajectory and severity. Understanding these mechanisms is critical for guiding the rational design of vaccines, antivirals, and immunomodulatory therapies, and for strengthening preparedness against these persistent zoonotic threats.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S1879625726000362?via%3Dihub

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Detection of #LaCrosse Virus #RNA in Clinical #Specimens Obtained from #Children with La Crosse Infection

 

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 patients.

Methods

Children who had positive arbovirus serology tests and a diagnosis of LACV encephalitis were identified. Remnant specimens including plasma, serum, CSF, throat swab (THT) or nasopharyngeal sample (NP) submitted to the laboratory for other diagnostic testing were retrieved and tested with LACV-PCR. Medical records were reviewed for demographics, presenting symptoms and test results.

Results

From June 2015 to October 2021, 61 patients had remnant specimens available for LACV-PCR and were included in this study. A total of 179 clinical specimens from these patients were tested, including 64 sera, 31 plasma, 33 CSF, 23 THT and 28 NP. Ten (5.3%) samples collected from 8 (13.1%) unique patients were positive for LACV RNA. The positive rates were 3.2%, 0, 6.5%, 3.5% and 21.7% for sera, plasma, CSF, NP and THT respectively.

Conclusion

There is limited utility of NAATs for diagnosis of LACV infection. NAATs may be useful in cases with delayed seroconversion or in immunocompromised individuals.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S1386653226000120?dgcid=rss_sd_all

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Detection of #WNV, #USUV and #Insect-Specific #Bunyaviruses in #Culex spp. Mosquitoes, #Greece, 2024

 

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 (USUV), and one pool was found positive, with sequence clustering into the EU-2 lineage. A subset of mosquitoes (737 pools) was tested for additional viruses, and bunya-like viruses were detected in 6 pools with sequences clustering into four distinct subclades. The prompt detection of pathogenic viruses is helpful for the design of control measures, while the detection of insect-specific viruses provides insights into viral diversity and evolution.

Source: Viruses, https://www.mdpi.com/1999-4915/17/11/1414

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Emergence of #Oropouche Virus in Espírito Santo State, #Brazil, 2024

Abstract

Oropouche virus (OROV), historically endemic to the Amazon, had spread to nearly all Brazil states by 2024; Espírito Santo emerged as a transmission hotspot in the Atlantic Forest biome. We characterized the epidemiologic factors driving OROV spread in nonendemic southeast Brazil, analyzing environmental and agricultural conditions contributing to viral transmission. We tested samples from 29,080 suspected arbovirus-infected patients quantitative reverse transcription PCR for OROV and dengue, chikungunya, Zika, and Mayaro viruses. During March‒June 2024, the state had 339 confirmed OROV cases, demonstrating successful local transmission. Spatial analysis revealed that most cases clustered in municipalities with tropical climates and intensive cacao, robusta coffee, coconut, and pepper cultivation. Phylogenetic analysis identified the Espírito Santo OROV strains as part of the 2022–2024 Amazon lineage. The rapid spread of OROV outside the Amazon highlights its adaptive potential and public health threat, emphasizing the need for enhanced surveillance and targeted control measures.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/6/24-1946_article

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#Vector competence for #Oropouche virus: A systematic #review of pre-2024 experiments

Abstract {1}

The 2023–24 epidemic of Oropouche fever in the Americas and the associated ongoing outbreak in Cuba suggests a potential state shift in the epidemiology of the disease, raising questions about which vectors are driving transmission. In this study, we conduct a systematic review of vector competence experiments with Oropouche virus (OROV, Orthobunyavirus) that were published prior to the 2023–24 epidemic season. Only seven studies were published by September 2024, highlighting the chronic neglect that Oropouche virus (like many other orthobunyaviruses) has been subjected to since its discovery in 1954. Two species of midge (Culicoides paraensis and C. sonorensis) consistently demonstrate a high competence to transmit OROV (~30%), while mosquitoes (including both Aedes and Culex spp.) exhibited an infection rate consistently below ~20%, and showed limited OROV transmission. Further research is needed to establish which vectors are involved in the ongoing outbreak in Cuba, and whether local vectors and wildlife communities create any risk of establishment in non-endemic regions.

Abstract {2}

Oropouche virus has recently become an urgent threat to public health in Central and South America. OROV is mainly transmitted by biting midges; however, some public health agencies and scientific sources note that some mosquito species transmit the virus. We conducted a systematic review of literature prior to the current epidemic, and identified seven studies that experimentally tested the ability of vectors to become infected with, and transmit OROV (i.e., that assessed their vector competence). These studies have consistently found that biting midges become infected at higher rates than mosquitoes, which rarely transmit the virus. It is unclear which vectors are responsible for transmitting OROV in the current outbreak. Existing published data support the observation that biting midges are likely to be significant vectors compared to mosquitoes, which are comparatively incompetent. However, increased vector surveillance and pathogen testing, and additional vector competence experiments using current OROV strains, are urgently needed.

Source: PLoS Neglected Tropical Diseases, https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013014

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#Congenital #Oropouche in #Humans: Clinical Characterization of a Possible New #Teratogenic Syndrome

Abstract

Oropouche fever is caused by the Oropouche virus (OROV; Bunyaviridae, Orthobunyavirus), one of the most frequent arboviruses that infect humans in the Brazilian Amazon. This year, an OROV outbreak was identified in Brazil, and its vertical transmission was reported, which was associated with fetal death and microcephaly. We describe the clinical manifestations identified in three cases of congenital OROV infection with confirmed serology (OROV-IgM) in the mother-newborn binomial. One of the newborns died, and post-mortem molecular analysis using real-time RT-qPCR identified the OROV genome in several tissues. All three newborns were born in the Amazon region in Brazil, and the mothers reported fever, rash, headache, myalgia, and/or retro-orbital pain during pregnancy. The newborns presented with severe microcephaly secondary to brain damage and arthrogryposis, suggestive of an embryo/fetal disruptive process at birth. Brain and spinal images identified overlapping sutures, cerebral atrophy, brain cysts, thinning of the spinal cord, corpus callosum, and posterior fossa abnormalities. Fundoscopic findings included macular chorioretinal scars, focal pigment mottling, and vascular attenuation. The clinical presentation of vertical OROV infection resembled congenital Zika syndrome to some extent but presents some distinctive features on brain imaging and in several aspects of its neurological presentation. A recognizable syndrome with severe brain damage, neurological alterations, arthrogryposis, and fundoscopic abnormalities can be associated with in utero OROV infection.

Source: Viruses, https://www.mdpi.com/1999-4915/17/3/397

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Co-Circulation of 2 #Oropouche Virus #Lineages during #Outbreak, #Amazon Region of #Peru, 2023–2024

Abstract

We describe introduction of the 2022–2023 Oropouche virus lineage from Brazil, which has caused large-scale outbreaks throughout Brazil, into the Amazon Region of Peru. This lineage is co-circulating with another lineage that was circulating previously. Our findings highlight the need for continued surveillance to monitor Oropouche virus in Peru.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/4/24-1748_article

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