In a follow-up on the Lassa fever outbreak affecting several states in Nigeria, the Nigeria Centre for Disease Control (NCDC) reports 68 Lassa fatalities since the outbreak began in mid-December 2016 through April 28.

Image/ C. S. Goldsmith, P. Rollin, M. Bowen This transmission electron micrograph (TEM) depicted numbers of Lassa virus virions adjacent to some cell debris. The virus, a member of the virus family Arenaviridae, is a single-stranded RNA virus, and is zoonotic, or animal-borne that can be transmitted to humans. The illness, which occurs in West Africa, was discovered in 1969 when two missionary nurses died in Nigeria, West Africa.In areas of Africa where the disease is endemic (that is, constantly present), Lassa fever is a significant cause of morbidity and mortality. While Lassa fever is mild or has no observable symptoms in about 80% of people infected with the virus, the remaining 20% have a severe multisystem disease. Lassa fever is also associated with occasional epidemics, during which the case-fatality rate can reach 50%. There are a number of ways in which the virus may be transmitted, or spread, to humans. The Mastomys rodents shed the virus in urine and droppings. Therefore, the virus can be transmitted through direct contact with these materials, through touching objects or eating food contaminated with these materials, or through cuts or sores. Because Mastomys rodents often live in and around homes and scavenge on human food remains or poorly stored food, transmission of this sort is common. Contact with the virus also may occur when a person inhales tiny particles in the air contaminated with rodent excretions. This is called aerosol or airborne transmission. Finally, because Mastomys rodents are sometimes consumed as a food source, infection may occur via direct contact when they are caught and prepared for food.
Image/
C. S. Goldsmith, P. Rollin, M. Bowen

In the current Lassa Fever outbreak, sixteen (16) States (Ogun, Bauchi, Plateau, Ebonyi, Ondo, Edo, Taraba, Nasarawa, Rivers, Kaduna, Gombe, Cross-River, Borno, Kano, Kogi and Enugu) have reported at least one confirmed case.

However, as of the end of April, Lassa is still active in nine states–Bauchi, Ondo, Edo, Taraba, Nasarawa, Kaduna, Kano, Kogi and Enugu.

In total, 164 Lassa cases have been reported with 149 cases being confirmed.

According to the US Centers for Disease Control and Prevention (CDC), Lassa fever is an acute viral illness that occurs in West Africa. The virus, a member of the virus family Arenaviridae, is a single-stranded RNA virus and is zoonotic, or animal-borne.

Lassa fever is a significant cause of morbidity and mortality. While Lassa fever is mild or has no observable symptoms in about 80% of people infected with the virus, the remaining 20% have a severe multisystem disease.

The animal host of Lassa virus is a rodent known as the “multimammate rat” of the genus Mastomys. Humans get infected with Lassa through aerosol or direct contact with excreta from the rodent. Laboratory infections do occur primarily through contaminated needles.

The symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. These include fever, retrosternal pain (pain behind the chest wall), sore throat, back pain, cough, abdominal pain, vomiting, diarrhea, conjunctivitis, facial swelling, proteinuria (protein in the urine), and mucosal bleeding. Neurological problems have also been described, including hearing loss, tremors, and encephalitis.

The Lassa virus and was 1st described in 1969 in the town of Lassa, in Borno State, Nigeria.

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