The Centers for Disease Control and Prevention (CDC) issued travel notices Friday for the West African countries of Nigeria and Benin due to current outbreaks of Lassa fever.


In Nigeria, the Nigeria Centre for Disease Control (NCDC) has reported 254 total cases, of which 129 have been confirmed by laboratory testing as of Mar. 14. The total number of deaths (suspected, probable and confirmed) is 137, with a case fatality rate (CFR) of 53.9 percent.

The states with the most cases are: Niger, Taraba, Kano, Edo, Bauchi, and Oyo.

In Benin, as of February 10, 2016, 71 cases have been reported and ay least 23 fatalities, according to public health authorities. The outbreak began in the district of Tchaourou in the Borgou Department, an area reporting the majority of cases.  Seven of Benin’s 12 departments report at least one case: Borgou, Collines, Alibori, Atlantique, Kouffo, Ouémé, and Littoral.

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.

If traveling to Nigeria or Benin, how can you prevent Lassa fever?

CDC says most preventive measures center around rats. They advise avoiding contact with rats, especially rat urine and feces; putting food away in rodent-proof containers; keeping the home clean and rodent proof; trapping rats in and around homes and do not eat rats.

In addition, washing hands well and often with soap, do not share eating or drinking utensils, clean surfaces that are frequently touched (such as toys, doorknobs, tables, and counters) regularly with soap and water or with cleaning wipes and avoid close contact with sick people.