The acute viral illness, Lassa fever, is no stranger to the west African country of Nigeria where the disease is endemic. In fact, during the previous two years, Nigeria has recorded more than 2,200 cases and nearly 80 deaths due to the zoonotic infection.

Nigeria map/CIA

According to the latest data from Nigeria Centre for Disease Control’s (NCDC), Federal Ministry of Health Weekly Epidemiology Report, Nigeria has seen 19 cases and one fatality since the beginning of the year.

Six of the 36 states have reported cases and the one death was from Bauchi State.

In 2014, Lassa fever was a serious problem in 23 of the 36 states of that country.

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.

Related: Lassa fever: 20 percent of cases could be due to human-to-human transmission, Cambridge study

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.