Monday, 9 April 2012

Lassa Fever In Nigeria


At the beginning of 2012, the Federal Ministry of Health in Nigeria notified the World Health Organisation of an outbreak of Lassa Fever in the country. As of 22nd March 2012, 623 suspected cases have been recorded and this includes 70 deaths from 19 out of the 36 States since the beginning of the year. Among the fatalities are 3 doctors and 4 nurses. The presence of the Lassa virus has been confirmed in 108 patients by laboratory analysis at the Irrua Specialist Teaching Hospital, Irrua, Edo State.   (It must be noted that this information is provisional and subject to change as more laboratory results of suspected cases becomes available.)

The Federal and State government have responded to the outbreak by setting up an emergency response team for the purpose of enhancing the disease surveillance to enable early detection, reinforce treatment of patients and conduct awareness campaigns among the affected population.

WHO does not advise or recommend any restriction on travel or trade with Nigeria but travellers returning from affected areas are however advised to seek medical advice if they develop symptoms of fever, malaise, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea and abdominal pain.


From this report it can be seen that Lassa fever cases have continue to increase in Nigeria. A previous report dated 22nd February 2012 stated that in the first six weeks of 2012 there had been 392 cases of Lassa fever and 40 fatalities across the country. The Minister of Health reported that 2 doctors and 4 nurses were among the dead and cases were reported in 12 states: Edo, Nasarawa, Plateau, Ebonyi, Taraba, Yobe, Ondo, Rivers, Gombe, Anambra, Delta and Lagos. Currently the outbreak has spread to 19 states.

Map of Nigeria

Lassa fever is a zoonotic disease caused by the Lassa virus. The rodent of the genus Mastomys – commonly known as the “multimammate rat” – is the animal reservoir host for the Lassa virus. Mastomys rodents infected with the Lassa virus do not become ill and they shed the virus in their excreta.

Image from CDC: Special Pathogen Branch

The virus was first discovered in 1969 when two missionary nurses died in the town of Lassa, Borno State, Nigeria.

Humans become infected with the Lassa virus when they are exposed to the excreta of infected Mastomys rodents and the infection can spread further between humans through direct contact with the blood, urine, faeces or other bodily secretions of persons with Lassa fever. Person-to-person transmission occurs in both community and health care settings where the virus may spread through contaminated medical equipment such as re-used needles. The virus is present in semen for up three months after the disease begins, thus sexual transmission of Lassa virus can occur however there is no epidemiological evidence supporting airborne spread of the virus between humans.

In the absence of an effective vaccine, rodent control is the best option for the control of the current outbreak. Health care workers should also follow strict hygiene procedures during nursing of patients so as to prevent secondary cases.

Other preventive measures include:
  • Good personal hygiene
  • Good environmental hygiene
  • Blocking all rodent hideouts
  • Food items like grains, garri, yam powders etc which are used at homes should be stored in plastic sealed containers or rodent-proof containers and not in cartons or bags.
  • Do not spread or keep food where rats can have access to them
  • Clean the top of any can drink before mouthing or better still use a straw
  • Public awareness about the outbreak of Lassa fever is also vital

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