Suspected human-to-human transmission of hantavirus aboard a Dutch cruise ship currently stranded in Cape Verde has drawn the attention of international health authorities. Three deaths have been reported, and the World Health Organization (WHO) is now raising the possibility of human-to-human transmission, a phenomenon considered rare for this type of virus.
According to Maria Van Kerkhove, acting director of the WHO's Department of Epidemic and Pandemic Prevention and Preparedness, the timeline of cases suggests that infected individuals contracted the virus before boarding their flights. The incubation period for hantaviruses, ranging from one to six weeks, supports this hypothesis. However, cases occurring among individuals in close contact suggest the possibility of human-to-human transmission, which is currently under investigation. The ongoing sequencing of the virus should allow for the precise identification of the strain involved.
Viruses transmitted by rodents
Hantaviruses are a family of viruses found worldwide, including in Europe. They are naturally hosted by certain rodents, such as rats and mice, which excrete the virus in their saliva, urine, and feces. In France, the Ministry of Health has identified four types involved in human infections: Puumala, Hantaan, Seoul, and Sin Nombre.
Human infection most often occurs through inhalation of airborne viral particles from rodent droppings. Less frequently, infection can occur through contact with broken skin, ingestion of contaminated food, or bites.
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Potentially serious clinical forms
Hantaviruses can cause two main types of illness in humans.
Hemorrhagic fever with renal syndrome (HFRS), prevalent in Europe, affects the kidneys and liver. It typically begins one to two weeks after exposure, with nonspecific symptoms (fever, headache, abdominal and back pain), which can progress to hypotension, internal bleeding, and acute kidney failure. Mortality varies depending on the viral strain but is usually low, with some forms being mild or even asymptomatic.
Hantavirus pulmonary syndrome (HPS), a more severe form, develops one to eight weeks after infection. After an initial flu-like phase (fever, fatigue, muscle aches), it progresses to acute respiratory distress with fluid accumulation in the lungs. Approximately 381% of patients who develop respiratory symptoms die from it.
A purely symptomatic approach
To date, there is no specific antiviral treatment for hantavirus. Management is based on supportive care: rest, hydration, and symptom relief. In severe cases, hospitalization in intensive care may be necessary. Patients with pulmonary syndrome may require respiratory support, while those with FHSR may require dialysis if they have kidney failure.
In this context, the cruise ship episode raises important questions about the modes of transmission of these viruses and recalls the need for close monitoring of zoonoses, at the interface between human health and the environment.
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