Lassa Fever
If you’ve been listening to the news in Nigeria lately, you most likely have heard about Lassa Fever which is said to have claimed about 40 lives across 10 states of the federation in this most recent outbreak.
Lassa fever is a severe and often fatal hemorrhagic illness caused by Lassa virus. The illness was discovered in 1969 when two missionary nurses died in Nigeria. The virus is named after the town in Nigeria where the first cases occurred. Since its original discovery, there have been countless outbreaks of various magnitude and severity across West Africa.
Lassa fever is a zoonotic disease, meaning that humans become infected from contact with infected animals. The reservoir, or host, of Lassa virus is a rodent known as the “multimammate rat” (Mastomys natalensis). Rodents infected with Lassa virus do not become ill, but they can shed the virus in their urine and faeces.
Transmission of Lassa virus to humans occurs most commonly through ingestion or inhalation. Coming into direct contact with urine and droppings from an infected rodent through touching soiled objects, eating contaminated food, or exposure to open cuts or sores, can lead to infection. Mastomys rodents are sometimes consumed as a food source and infection may occur when rodents are caught and prepared. Contact with the virus may also occur when a person inhales tiny particles in the air contaminated with infected rodent excretions. This aerosol or airborne transmission may occur during cleaning activities, such as sweeping. Person-to-person transmission may occur after exposure to virus in the blood, tissue, secretions, or excretions of a Lassa virus-infected individual. Casual contact (including skin-to-skin contact without exchange of body fluids) does not spread Lassa virus.
About 80% of people who become infected with Lassa virus have no symptoms. The other 20% result in severe disease, where the virus affects several organs such as the liver, spleen and kidneys. In the early stages, Lassa fever is often misdiagnosed as influenza, typhoid or malaria, and as a result many patients fail to receive appropriate medical treatment. Making a correct diagnosis of Lassa fever is made difficult by the wide spectrum of clinical effects that manifest, ranging from asymptomatic to multi-organ system failure and death. The onset of the illness is typically indolent, with no specific symptoms that would distinguish it from other febrile illnesses.
Early signs include fever, headache and general malaise, followed by a sore throat, nausea, vomiting, abdominal pain and diarrhea in some cases. After 4 to 7 days, many patients will start to feel better, but a small minority will proceed to display symptoms such as edema, hypertension, bleeding, respiratory distress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen and shock. Neurological problems have also been described, including hearing loss, tremors, and encephalitis.
Death from Lassa fever most commonly occurs 10 to 14 days after symptom onset.
The most common complication of Lassa fever is deafness. Various degrees of deafness occur in approximately one-third of infections, and in many cases hearing loss is permanent. As far as is known, severity of the disease does not affect this complication: deafness may develop in mild as well as in severe cases. In infected pregnant mothers, spontaneous abortion is a serious complication of infection with an estimated 95% mortality.
Presently there is no vaccine for Lassa fever currently available for use in humans, and the only available drug, ribavirin, is only effective if administered early in infection (within the first 6 days after disease onset). Patients should also receive supportive care consisting of maintenance of appropriate fluid and electrolyte balance, oxygenation and blood pressure, as well as treatment of any other complicating infections.
Prevention of Lassa fever relies on promoting good “community hygiene” to discourage rodents from entering homes. This would mean encouraging your neighbors to also keep the neighbourhood clean. Other effective practices include:
- storing grain and other foodstuffs in rodent-proof containers, so you can empty your bag of rice or garri into a plastic bin which has a lid.
- Disposing of garbage far from the home, in approved garage disposal bins which should be covered to prevent rodents from visiting.
- Setting rat traps or fumigating the home to eliminate any rats that may be in the home already.
- Look out for rat droppings around you, paying particular attention to the kitchen and food storage areas.
- Cooking all food thoroughly
- Always wipe cans/tins of food or drink before opening.
- Wash your hands regularly with soap AND running water. Washing under running water is better than washing inside a bowl of water.
- It may also be wise not to use rodents as a food source i.e STOP EATING BUSH MEAT.
