The U.K. Health Security Agency (UKHSA) has reported three cases of Lassa fever in the past week. It is an acute viral illness and has taken the life of a baby so far.
According to the U.S. Center for Disease Control and Prevention (CDC) website, Lassa fever is a disease of animal origin that is endemic to Western African countries such as Sierra Leone, Liberia, Guinea, and Nigeria. The disease is caused by the Lassa virus, named after the town in Nigeria, where it was first reported in 1969.
This disease is caused by the multimammate rat, Mastomys natalensis, more commonly known as the African rat.
The host African rat sheds the virus in its urine and droppings for extended periods of time, sometimes its entire lifetime. Since rats like to infest areas near human settlements, they can transfer the virus to humans by contaminating food or even direct contact.
Humans can get the Lassa virus by inhalation of the virus particles or ingestion of food contaminated by the virus. Once a human is infected, it can be transferred to other humans via the exchange of bodily fluids such as saliva or by encountering infected blood, tissue, or human excreta as well.
In the case of U.K. patients, they had a history of travel to Western Africa recently.
Symptoms of Lassa fever can be seen as early as one week but even as late as up to three weeks after exposure. For most individuals, the symptoms are mild such as mild fever, fatigue, and headache.
About 20 percent of the infections see respiratory distress, repeated vomiting, swelling on the face, pain in the chest and back as well as hemorrhaging, internal or external bleeding from the eyes, nose, or gums.
Up to 20 percent of those infected need hospitalization due to the illness. In many cases, the hearing loss is permanent. Statistically, only one percent of those infected with the virus die but pregnant women in their third trimester are at high risk since the infection can lead to spontaneous abortion with a 95 percent mortality of fetuses, CDC states on its website.
The newborn child in the UK succumbed to the disease but contract tracing efforts haven’t shown that the infection has spread further yet. The staff at the hospitals where the family was being treated have been asked to observe isolation for two weeks, just to be sure.
According to a UKHSA statement, the U.K. has seen eight cases of the Lassa virus so far since the 1980s, with the last two occurring as far back as 2009.