In a follow-up on the Lassa fever outbreak in West Africa,  one new laboratory confirmed case was reported from Edo state while 9 new suspected cases were reported from Kano (5 cases) and Bauchi (4 cases) states of Nigeria in the past week. Laboratory results of the 9 suspected cases from Kano and Bauchi states are pending.

Nigeria map/CIA

As of Apr. 7, a total of 430 suspected cases including 79 deaths (case fatality rate of 18.4 %) were reported from 15 states in Nigeria.

The current outbreak started on 16 December 2016 in Ogun State, Nigeria when the initial case, a healthcare worker, presented to a federal medical centre. This initial case followed the death of another hospital staff, whose cause of death was not well understood. The disease eventually increased in number and spread to 14 other states in Nigeria, and to three neighboring countries of Benin, Togo and Burkina Faso.

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.