Virus World

The patient is a soldier who had recently returned from abroad. People who may be at risk through contact with him are being traced. A case of Lassa fever - endemic to West Africa and spread by rats - has been reported in the Paris region. The patient, a soldier who had recently returned from abroad, is now in the Bégin military hospital in Saint-Mandé (Val-de-Marne).  The Ministry of Health has said that an “in-depth epidemiological investigation is under way to determine the persons who may have been in contact with him”. It said his condition “does not give cause for concern”.

What is Lassa fever?

The fever takes its name from the town where it was first identified and isolated - Lassa in Nigeria, West Africa - and where it killed a nurse in 1969. It is now common in Nigeria, Guinea, Liberia, and Sierra Leone, and cases have also been reported in Cote d’Ivoire and Burkina Faso. There have been two epidemics in Benin in recent years; one in 2014 and another in 2016. The virus kills between 5,000 and 6,000 people per year in West Africa, and infects between 100,000 and 300,000 people. Its incubation period - from infection to symptoms - varies from two to 21 days. “The virus circulates almost constantly, especially in Nigeria, which is the worst-affected country,” said Sylvain Baize, head of the emerging viral infections unit at the Institut Pasteur, to BFMTV. “In all, it is estimated that 160 to 180 million people are potentially at risk.”

How does Lassa fever spread?

The virus is spread by rat faeces from the Natal rat (Mastomys natalensis), which is native to West Africa. The World Health Organization states: “The virus can also be transmitted from human to human by direct contact with the blood, urine, excrement or other bodily secretions of a contaminated person.”

What are the symptoms of Lassa fever?

In 80% of cases, it causes no symptoms. However, in the remaining 20%, symptoms come on gradually and become increasingly severe. They include fever, vomiting, nausea, stomach pain, and headaches.  In 15% of cases, symptoms are worse, and include oedema (fluid build-up); pleurisy (inflammation of the lung lining); and oral, nasal or vaginal haemorrhage. The fever is fatal in around 1% of cases, as it goes on to cause organ failure. Of those who develop serious symptoms and do survive, some will have lasting heart problems, and 25% will become deaf. Only half of these will recover their hearing after one to three months.

It is especially dangerous for pregnant women.

What is the treatment for Lassa fever?

So far, only one treatment has been identified. This is the antiviral agent ribavirin. This must be given very soon after infection to be effective.  However, because the symptoms of the fever typically appear similar to other conditions (including malaria and dysentery), by the time the condition is confirmed, it is usually too late to give the drug. There is no vaccine yet available, although the Institut Pasteur released promising results to an international phase one trial in April. After-effects sometimes appear in those who survive this fever: 25% become deaf. Only half recover their hearing after one to three months.

May 3, 2024

The French capital and various other areas will have movement restricted as cases rise.  Some 21 million people in 16 areas of France will be placed under the measures from midnight on Friday. These measures will not be as strict as the previous lockdown, Prime Minister Jean Castex said, with people allowed to exercise outdoors. France has recorded more than 35,000 new infections within the past 24 hours. Mr Castex said a "third wave" of infections in the country was looking increasingly likely. The situation in Paris is particularly worrying with 1,200 people in intensive care there, more than at the peak of the second wave in November, Health Minister Olivier Véran said. Under the new measures, non-essential businesses will be forced to close, but schools will remain open, along with hairdressers if they follow a "particular sanitary protocol". Government spokesman Gabriel Attal stressed there would be differences with the two earlier lockdowns and said further details would be given of which business could stay open or would have to shut. People will be allowed to exercise outdoors within 10km (6 miles) of their home and are not allowed to travel to other parts of the country unless they have a valid reason. Those in the affected areas will have to fill out a form to explain why they have left their homes.

There is a “window of opportunity” in the weeks after someone is infected with HIV where treatment may lead to better control later on, researchers say. Treatment for human immunodeficiency virus (HIV) four weeks after infection may make it possible to control the virus without medication in the long term, a new study has shown. The finding reinforces the importance of detecting HIV early, according to researchers from the French Institut Pasteur, CEA, Inserm, University of Paris Cité, and the University of Paris-Saclay. Treatment for HIV is called antiretroviral therapy (ART) and can be taken as a pill or an injection. The goal is to reduce a person’s viral load to an undetectable level so the person has no risk of transmitting HIV.

This therapy is now so effective that it can fully control the virus, with researchers even exploring ways to cure it. This latest study looked at the impact of early treatment on primates with simian immunodeficiency virus (SIV), which is closely related to HIV. The researchers found that very early treatment for two years led to controlling the virus even after treatment was interrupted. “We show an association between early treatment and control of the infection after treatment is stopped, and our study indicates the existence of a window of opportunity to promote remission of HIV infection,” Asier Sáez-Cirión, head of the Institut Pasteur’s viral reservoirs and immune control unit and co-senior author of the study, said in a statement. A previous 2013 study in humans had shown a similar possibility, suggesting that early treatment could allow people to stop treatment, with the virus in a “state of remission”. The latest study also showed that the benefits of early treatment were lost if therapy was started just five months later. The findings were published in the scientific journal Nature Communications.

By sampling sewage across greater Paris for more than 1 month, researchers have detected a rise and fall in novel coronavirus concentrations that correspond to the shape of the COVID-19 outbreak in the region, where a lockdown is now suppressing spread of the disease. Although several research groups have reported detecting coronavirus in wastewater, the researchers say the new study is the first to show that the technique can pick up a sharp rise in viral concentrations in sewage before cases explode in the clinic. That points to its potential as a cheap, noninvasive tool to warn against outbreaks, they say.

“This visibility is also going to help us predict a second wave of outbreaks,” says Sébastien Wurtzer, a virologist at Eau de Paris, the city’s public water utility. Wurtzer and his colleagues posted the study, which has not been peer-reviewed, on the preprint repository medRxiv on 17 April. Sewers offer near–real-time outbreak data, because they constantly collect feces and urine that can contain coronavirus shed by infected humans. (Once excreted from the body, the virus degrades quickly, although scientists have found limited instances of infectious virus in fecal matter.) Polymerase chain reaction testing identifies fragments of RNA from SARS-CoV-2, the virus that causes COVID-19. Higher concentrations of virus in the wastewater corresponds to higher numbers of infected people who contribute to the sewer system.

For the Paris study, Wurtzer and his colleagues sampled wastewater from up to five Paris-area plants twice a week between 5 March and 7 April. They noted “high concentrations” of viral RNA several days before 10 March, the first day that Paris recorded multiple deaths from COVID-19. Concentrations continued to rise a few days ahead of an acceleration in clinical cases and deaths in Paris. “We have a very clear curve that precedes the curve in numbers of clinical cases, and now with confinement, we see a flattening of that curve,” says Laurent Moulin, a study co-author and a microbiologist also at Eau de Paris. He estimates it took between a half a day and 3 days for the sewage to move from toilets to the treatment plants.

Preprint available at medRXiv (April 17, 2020):

https://www.medrxiv.org/content/10.1101/2020.04.12.20062679v1