The Travel Health and Vaccine Specialists

Health Alert


Lassa Fever in Benin

Updated April 1, 2016

What is the Current Situation?

Public health authorities in Benin have reported an outbreak of Lassa fever. From January 21, 2016, to March 21, 2016, 51 cases have been reported. The outbreak began in the district of Tchaourou in the Borgou Department, an area reporting the majority of cases.  The following departments reported at least one case during this period: Kouffo, Donga, Alibori, Littoral, Plateau, Ouémé, Collines, and Borgou.

What is Lassa Fever?

Lassa fever is a viral illness that is spread by rats. People get the disease through:

  • Direct contact with rat droppings or urine
  • Catching and preparing rats as food
  • Breathing in tiny particles in the air that are contaminated with rat droppings or urine
  • Direct contact with a sick person’s blood or body fluids

Most people who have Lassa fever have mild symptoms, including a slight fever, feeling tired and weak, and headache. Some people have more serious symptoms like bleeding from the mouth or nose; difficulty breathing; vomiting; facial swelling; pain in the chest, back, and abdomen; and shock. Symptoms usually occur 1 to 3 weeks after a person has been infected. Lassa fever is mainly found in Sierra Leone, Guinea, and Nigeria. Other neighboring countries are also at risk because the type of rat that spreads the virus is also found throughout West Africa. Lassa fever can occur all year long, but most cases occur from January to May.

What Can Travelers Do to Prevent Lassa Fever?

  • Avoid contact with rats, especially rat urine and feces.
  • Put food away in rodent-proof containers.
  • Keep the home clean and rodent proof.
  • Trap rats in and around homes.
  • Do not eat rats.

Stay away from germs by:

  • Washing hands well and often with soap, and teach children to wash their hands, too.
  • Not sharing eating or drinking utensils.
  • Cleaning surfaces that are frequently touched (such as toys, doorknobs, tables, and counters) regularly with soap and water or with cleaning wipes.
  • Avoiding close contact with sick people.

If you are sick and think you have Lassa fever:

  • See a health care provider right away. Be sure to tell your health care provider that you have recently traveled to Benin.

Clinician Information:

US-based clinicians should notify local health authorities and CDC’s Viral Special Pathogens Branch immediately of any suspected cases of VHF occurring in patients residing in or requiring evacuation to the United States: 404-639-1115 or the CDC Emergency Operations Center at 770-488-7100 after hours. CDC also provides consultation for international clinicians and health ministries.

Lassa fever is most often diagnosed by using reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent serologic assays (ELISA), which detect IgM and IgG antibodies, as well as Lassa antigen. Immunohistochemistry performed on tissue specimens can be used to make a post-mortem diagnosis. Samples for testing should be sent to reference laboratories with Biosafety level 3 and 4 capabilities.

Patients should receive supportive care consisting of maintenance of fluid and electrolyte balance, oxygenation, and blood pressure, as well as treatment of any other complicating infections.

Ribavirin, an antiviral drug, has been used to treat Lassa fever patients. It is most effective when given early in the course of the illness. Intravenous ribavirin can be obtained for compassionate use through FDA from Valeant Pharmaceuticals (Aliso Viejo, California). Requests should be initiated by the provider through FDA (301-796-1500 or after hours 866-300-4374), with simultaneous notification to Valeant Pharmaceuticals: 800-548-5100, extension 5 (domestic telephone). The process is explained on FDA’s website.

Additional Information: