According to the World Health Organization (WHO), Lassa fever is an acute viral haemorrhagic illness of about two to twenty-one days duration that occurs in the western part of Africa. The virus is transmitted to humans via contact with food or household items contaminated with rodent urine or faeces.
One person to another infections and laboratory transmission can also occur, particularly in clinics that lack adequate infection prevention and control measures.
Lassa fever is known to be endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, and Nigeria, but probably exists in other West African countries. Very early supportive care with rehydration and symptomatic treatment improves survival.
Background of Lassa fever
The virus causing Lassa fever was not identified until the year 1969 which is a single-stranded RNA virus belonging to the virus family of Arenaviridae and about eighty per cent of people who become infected with the virus have no symptoms.
One out of five infections results in severe disease, where the virus affects several organs such as the liver, spleen and the kidneys.
Lassa fever is known to be endemic in Benin (where it was first diagnosed for the first time in Nov. 2014), Ghana (diagnosed for the first time in October 2011), Guinea, Liberia, Mali (diagnosed for the first time in Feb. 2009), Sierra Leone, and Nigeria.
Symptoms of Lassa fever
According to the WHO, the incubation period of Lassa fever ranges from 6 – 12 days. The onset of the disease, when it is symptomatic, is usually gradual, starting with fever, general weakness, and malaise. After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough and abdominal pain set in.
In severe cases, facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop. Protein may also be noted in the urine. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages.
Death usually occurs within 14 days of onset in fatal cases. The disease is especially severe late in pregnancy, with maternal death and/or fetal loss occurring in more than eighty per cent of cases during the third trimester.
Outbreak in Nigeria
According to Wikipedia, the outbreak of Lassa fever occurred in Nigeria in 2018 and spread to eighteen states across the country. The disease was the largest outbreak of Lassa recorded.
As of February 25, 2018, there were about one thousand and eighty-one suspected cases and ninety reported deaths; three hundred and seventeen of the cases and seventy-two deaths were confirmed as Lassa.
According to the WHO, as of 22 February 2018, ten suspected cases who took ill in Nigeria were reported in Benin and confirmed cases from Beninese states that boarder Nigeria. The outbreak of the disease is considered active in one Nigerian state that boarders Benin and two that boarder Cameroon.
Health care Centers for Lassa fever in Nigeria
14 health care workers were affected in six states (Benue, Ebonyi, Edo, Kogi, Nasarawa and Ondo states), with four deaths (case fatality rate of twenty-nine per cent). As of the 18th of February, four out of the fourteen health care workers were confirmed positive for Lassa fever.
According to the WHO, Lassa fever case management centers are operational in four states of the country which are; Anambra, Abakaliki, Edo and Ondo states. The workers working in these centers are trained in standard infection control and prevention (IPC) as well as use of personal protective equipment (PPE).
In addition, the suspected cases and deaths reported in the community settings are being actively investigated by the field teams and contacts are being followed up.
Currently, three laboratories are operational and testing samples for Lassa fever by polymerase chain reaction (PCR). The World Health Organization continues to support the outbreak response, mainly in the domains of enhanced surveillance, contavt tracing, strengthening of diagnostic capacity and risk communication.
Note: According to the Nigeria Center for Disease Control (NCDC), the first outbreak of Lassa disease was in January 2017 which resulted in multiple deaths.
Lassa fever occurs in all age groups and both sexes. People at greater risk are those living in rural areas where rodents are usually found, especially in communities with poor sanitation or crowded living conditions.
Health workers are at risk if caring for Lassa fever patients in the absence of proper barrier nursing and infection prevention and control practices
Prevention and Control
The prevention of Lassa fever relies on good hygiene to keep away rodents from entering into the house. Storing of grains and other foodstuffs in rodent-proof containers, disposing of garbage far from the home, and keeping of pussy cats are some of the effective measures of preventing the disease from breaking out.
In health-care environments, workers should always apply standard infection prevention and control precautions when caring for patients, regardless of their presumed diagnosis which include basic hand hygiene, respiratory hygiene, use of personal protective equipments, safe injection practices and safe burial practices.
Health workers caring for patients with suspected or confirmed Lassa fever should apply extra infection control measures to prevent contact with the patient’s blood and body fluids.
Treatment of Lassa fever
The antiviral drug ribavirin seems to be an effective treatment for Lassa fever if administered early enough of clinical illness.
There is no evidence to support the role of ribavirin as post-exposure prophylactic treatment for Lassa fever. There is currently no vaccine that protects against the disease.
. World Health Organization (WHO)
. Nigeria Center for Disease Control (NCDC)