Since January 2016, the World Health Organization (WHO) has been notified of Lassa fever outbreaks in Nigeria, Benin, and Togo, with cases linked to the Togo outbreak in both Cologne, Germany and Atlanta, Georgia in the United States.
Native to West Africa, lassa fever
was discovered in 1969 after two missionary nurses died in the town of Lassa, Nigeria. According to the Centers for Disease Control and Prevention (CDC), lassa fever is known to be endemic in Guinea, Sierra Leone, Liberia, and Nigeria, although surrounding regions do experience occasional outbreaks. Of the virus family, Arenaviridae
, lassa fever is spread through the urine and feces of an infected Mastomys
Complications and Symptoms of Lassa Fever
Deafness is the most common complication associated with lassa fever. Deafness occurs in about one third of cases, whether they be mild or severe, and can develop into either temporary or permanent deafness. In addition, an estimated 95% of pregnant women infected with the virus end up having a miscarriage.
Approximately 80% of infections are mild and undiagnosed. Individuals usually develop symptoms of the virus, such as slight fever, general malaise, or weakness, 1-3 weeks after infection. For the 20% of infected individuals who develop severe forms of the disease, symptoms
- Hemorrhaging of the gums, eyes, or nose
- Respiratory distress
- Constant vomiting
- Swelling of the face
- Abdomen and chest pains
Only 1% of lassa patients die due to the virus, however, 15-20% of lassa hospitalizations result in death. The number of lassa-associated hospitalization deaths can reach 50% during epidemics.
2016 Lassa Outbreaks in West Africa
Nigeria sees a peak of lassa fever cases on an annual basis between December and February. The country’s latest
lassa fever outbreak lasted from August 2015 until January 23, 2016, with four states accounting for 54% of confirmed cases and 52% of reported deaths: Bauchi, Edo, Oyo, and Taraba. A total of 159 suspected cases of lassa fever were reported in the country, including 83 deaths.
Included in the number of cases mentioned above, is 4 lab-confirmed cases of lassa fever in health care workers (of which two have since died).
The WHO office of Nigeria worked closely with the Federal Ministry of Health (MoH) to respond to and contain the outbreaks.
Between January 25 and February 16, 2016, Benin also experienced a Lassa outbreak
, with a total of 71 cases and 2 deaths.
More recently, Togo experienced its first two cases
of lassa fever. The affected area borders Benin, which lead WHO officials to believe that the infection spread from Benin into Togo territory. Sequencing and epidemiological investigation has ruled out the possibility of viral relation to the Nigeria outbreak, however, further investigation is needed.