A virus rarely detected in France. A patient suffering from Lassa fever is hospitalized at the Bégin military hospital, in Saint-Mandé, in Val-de-Marne, BFMTV learned this Thursday, May 2. This virus is rare in the northern hemisphere because it is endemic in West Africa, particularly Nigeria, Guinea, Liberia and Sierra Leone.
“The virus circulates almost permanently, especially in Nigeria, the most affected but also the most populous country in Africa. In total, it is estimated that between 160 and 180 million people are potentially at risk,” explains Sylvain Baize, head of the department of biology. Emerging viral infections unit of the Pasteur Institute.
Isolated cases have also been reported in Ivory Coast and Burkina Faso, according to the United States Centers for Disease Control and Prevention. Two epidemics were recorded in Benin in 2014 and 2016.
5,000 to 6,000 deaths per year
This hemorrhagic fever infects between 100,000 and 300,000 people each year and causes between 5,000 and 6,000 deaths per year according to the Pasteur Institute. The virus takes its name from the city where it was first isolated in Nigeria in 1969 and where it killed a nurse.
Lassa fever is the most common hemorrhagic fever in northern countries: as of September 2019, more than twenty cases had been recorded since 1969.
The source of this disease? A small rodent called the Natal rat that lives in West Africa. It transmits Lassa fever to humans through its feces.
“The virus can also be transmitted from person to person through direct contact with the blood, urine, excrement or other organic secretions of an infected person,” specifies the World Health Organization.
This person-to-person transmission has been reported in hospitals, particularly when hygienic conditions are not optimal.
80% of cases are asymptomatic.
This disease is difficult to detect because, in 80% of cases, it does not present symptoms. In the remaining 20% of cases, these symptoms, which appear gradually, are generally non-specific: they are fevers, vomiting, nausea, abdominal pain, headaches, etc.
In 15% of cases, symptoms may worsen. Then edema, pleurisy, oral, nasal or even vaginal bleeding appear.
In 1% of cases, Lassal fever is fatal. And this, within 14 days after the appearance of symptoms. Please note that pregnant women are at special risk.
The virus “frequently leads to the death of the mother and systematically to that of the fetus,” warns the Pasteur Institute.
Sometimes after-effects appear in those who survive this fever: 25% become deaf. Only half recover their hearing after one to three months.
Currently there is only one treatment to treat Lassa fever: ribavirin, an antiviral. However, it is only effective if given very quickly after infection. However, since the symptoms are not very specific, by the time the diagnosis is made it is often too late to administer it.
No vaccine has yet seen the light of day. However, clinical trials are underway. On April 28, the Pasteur Institute reported favorable results from the internationally conducted Phase 1 clinical trial of a vaccine candidate.
Source: BFM TV
