One of the three persons diagnosed with Lassa fever in the UK has died in February 2022. The cases have been linked to travel to west African countries. The Lassa virus is named after a town in Nigeria where the first cases were discovered. The death rate associated with this disease is low, at around one per cent. But the death rate is higher for certain individuals, such as pregnant women in their third trimester. According to the European Centre for Disease Prevention and Control, about 80 per cent of the cases are asymptomatic and therefore remain undiagnosed. Some patients may need to be hospitalised and develop severe multi-system disease. Fifteen per cent of the hospitalised patients may die. The Lassa fever-causing virus is found in West Africa and was first discovered in 1969 in Lassa, Nigeria, the Centers for Disease Control and Pollution (CDC) notes. The discovery of this disease was made after two nurses died in Nigeria. The fever is spread by rats and is primarily found in countries in West Africa including Sierra Leone, Liberia, Guinea, and Nigeria where it is endemic. A person can become infected if they come in contact with household items of food that is contaminated with the urine or feces of an infected rat. It can also be spread, though rarely, if a person comes in contact with a sick person’s infected bodily fluids or through mucous membranes such as the eyes, nose or the mouth. Person-to-person transmission is more common in healthcare settings. Even so, people don’t usually become contagious before symptoms appear and cannot transmit the infection through casual contact such as through hugging, shaking hands or sitting near someone who is infected. Symptoms typically appear 1-3 weeks after exposure. Mild symptoms include slight fever, fatigue, weakness and headache and more serious symptoms include bleeding, difficulty breathing, vomiting, facial swelling, pain in the chest, back, and abdomen and shock. Death can occur from two weeks of the onset of symptoms, usually as a result of multi-organ failure. The CDC notes that the most common complication associated with the fever is deafness. Nearly one-third of those infected report various degrees of deafness. In many such cases, the hearing loss can be permanent. Significantly, deafness can occur in both mild as well as severe presentations of the fever. The best way to avoid getting infected is to avoid contact with rats. This means avoiding contact with rats not only in places where the disease is endemic, but also maintaining hygiene in other areas to prevent rats from entering the house, keeping food in rat-proof containers and laying down rat traps, the CDC advises.