Three deaths, several infected passengers and an extremely rare virus capable of being transmitted between humans… For several days, the hantavirus has been shaking the whole world.
On board the cruise ship “MV Hondius,” several people have in fact been infected by the Andes strain (ANDV), generally linked to exposure to infected rodents. But how could this virus have spread so easily on a boat? And above all, how can we explain this unusual mode of transmission, from rodents to humans? Dr Gérald Kierzek, emergency doctor and medical director of True Medical, answers us.
Rare human-to-human transmission
Hantavirus is not usually transmitted from person to person: only rodents are infected. They excrete the virus in their urine, saliva and droppings, which then contaminate their environment (particularly dust, surfaces, food or closed spaces). But last week, a rare outbreak of Andes strain hantavirus contamination was identified on board the cruise ship MV Hondius… and hit several passengers.
Generally, “hantaviruses circulate in a zoonotic mode (from animals to humans), without lasting epidemic transmission between humans. With the Andes strain, chains of human-to-human transmission have been observed, with secondary then tertiary cases. This modifies the surveillance, isolation and contact tracing strategies put in place by health authorities. underlines Dr Gérald Kierzek.
According to Dr Liam Brierley, MRC Virus Research Center (UK) “it is (…) extremely likely that these cases result from the same occasional exposure to rodents.” Nevertheless, “the long incubation period will make it difficult to pinpoint precisely when and where this occurred,” she specifies.
And if the World Health Organization already reports 6 confirmed cases out of 8 suspects, and several deaths (three deaths have been reported), how can we explain the spread of this virus on board?
Contaminated microparticles
Unfortunately for passengers, a simple inhalation is enough to become contaminated.
“Humans contract the virus by inhaling dust or microdroplets containing excreta from infected rodents, sometimes following a bite or contact with contaminated surfaces or food,” indicates the medical director of True Medical.
On board the famous boat, all the conditions were therefore met to promote the spread and transmission of this virus:
- Rodents are often present on board the holds, sheds and technical areas of boats;
- Containment, shared ventilation, prolonged promiscuity on board, as well as cleaning or moving dusty stocks encourage the formation of contaminated aerosols;
- Finally, when an “index” case appears (i.e. the first contaminated person), the closed environment and close and prolonged contact (cabins, dining rooms, on-board care) can promote human-to-human transmission.
Andes strain: which profiles are most at risk?
People sharing a cabin, providing care or assisting a patient (close contact, exposure to saliva or other biological fluids, etc.) are most exposed to human-to-human transmission of the Andes virus.
“The available data on hantaviruses also show that young and middle-aged adults are frequently affected. The severity of the infection, however, depends above all on the speed of treatment and the initial cardio-respiratory state,” explains Dr. Gérald Kierzek.
For patients with underlying pathologies (such as renal failure, chronic cardio-respiratory disease or immunosuppression), caution is required: they could see their prognosis deteriorate more quickly.
Finally, age also matters in the progression of the disease: older people seem more vulnerable to severe complications, particularly in the presence of comorbidities.
And the information available to date proves it: all those infected were over 40 years old, and the first case – Leo Schilperoord, considered the presumed “patient zero” of the epidemic – is 70 years old.
A lethality closer to Ebola than to Covid
Nevertheless, during his intervention on LCI on Monday May 11, the epidemiologist and professor of public health at Paris-Cité University, Antoine Flahault specified that according to scientific studies, “we can see that the lethality, that is to say the number of deaths in relation to the number of infected, is of the order of 30 to 40%. It is particularly high, which brings us closer to the Ebola or SARS type virus than to Covid-19 or the flu.“.
A new meeting is planned for today in Matignon.