Preventing Lassa fever infection

Lassa fever has broken out again in some parts of the country. The virus is said to have been circulating in Nigeria for over a thousand years and in some other West African Countries for hundreds of years.

Recently, the Nigeria Centre for Disease Control (NCDC), alerted on the increasing number of Lassa fever cases, even as it advised increased focus on preventions and preparedness. It said since last December till date, 19 cases and six deaths have been recorded in seven states.

Health experts are also warning that families, communities and individuals should protect themselves, avoid foods contaminated by rats and keep their environment clean. People should not allow bushes to grow in their environment to free themselves from the rodents carrying the Lassa viruses.

Consultant Virologist at the College of Medicine, Idi-Araba, Lagos, Prof. Sunday Aremu Omilabu, said Lassa fever is a severe and often fatal hemorrhagic illness, caused by the Lassa virus. “Since its discovery in 1969 in the village of Lassa in Borno State, Nigeria, there have been countless outbreaks of various magnitude and severity across West Africa,” he explained. “Estimates of annual incidences of Lassa fever across this region have recorded high infection and death rates.

The Lassa virus is a member of the Arenaviridae virus family. Humans contract the virus primarily through contact with the contaminated excreta of Mastomys natalensis rodents, commonly known as the Multimammate rats, which are the natural reservoirs for the virus. Little is known regarding the transmission of the virus from the rodent reservoir to the human host, although there is compelling evidence that Arenaviruses are stable and infectious by the aerosol route in nonhuman primates.

“The rodents live in bushes, but because of dry season, they run to our houses for protection and live with humans and deposit excreta on floors, tables, beds and foods”.

“The foods that are being contaminated by the rodents include, garri, yam, rice and beans, among others. So, people should cover their foods properly, avoid taking soaked garri that is not well covered. The rodents, while feeding on the foods, defecate and urinate on it, which make them, not fit for human consumption. Therefore, people should not eat leftover foods without warming them properly. Environmental hygiene is very important to enable people protect themselves from been infected by the virus.”

Omilabu explained that the virus is transmitted to humans through cuts and scratches. In some regions, Mastomys rodents are also consumed as foods, but it is better for people to avoid contact with rodents. Secondary transmission of the virus occurs through direct contact with infected blood or bodily secretions.

“This occurs mainly between individuals caring for sick patients, although anyone who comes in close contact with a person carrying the virus is at risk of infection. Nosocomial transmission occurs as a result of treatment in a hospital and outbreaks in healthcare facilities in endemic areas represent a significant burden on the healthcare system.

According to Omilabu, at the early stages, Lassa fever is often misdiagnosed as influenza, typhoid or malaria, as a result of which many patients fail to receive appropriate medical treatment. Making a correct diagnosis of Lassa fever is rendered difficult by the wide spectrum of clinical effects, which range from asymptomatic to multi-organ system failure and death. The onset of the illness is typically indolent, with no specific symptoms distinguishing it from other febrile illnesses.

He listed some symptoms of Lassa fever to include fever, headache and general malaise, followed by a sore throat, nausea, vomiting, abdominal pain and diarrhoea in some cases.

He said: “After four to seven days, many patients will start to feel better, but a small minority will proceed to display symptoms such as edema, hypertension, bleeding and shock. Death from Lassa fever most commonly occurs between 10 to 14 days after symptom onset, if not properly handled.

“Moreover, the impact of the disease in endemic regions of West Africa is immense, which means to diagnose, treat and prevent this viral hemorrhagic fever will provide a significant public health benefit. Suspected cases should be reported to hospitals for proper medical tests and treatments.

“However, one of the hallmarks of Lassa virus infection is the apparent absence of functional antibodies during acute infection. A fundamental understanding of the mechanisms of antibody-mediated neutralisation of Lassa virus may have significant implications for the generation of antibody-based therapeutics or epitope-targeted vaccines.

“Lassa fever is endemic in West Africa. Confirmed incidences have been recorded in Sierra Leone, Liberia, Guinea, Nigeria and Mali. However, concerns exist that there may be Lassa viruses in other countries, such as Central African Republic, Ghana, Mali, Ivory Coast, Togo, Benin and Cameroon.

“Furthermore, Mastomys rodents are distributed across the African continent, indicating a strong possibility for the spread of the disease they carry.

“People should not litter their homes, because the rodents hide and feed on waste materials that litter the environment. “Government should provide health education for the people, by creating radio and television jingles, including other networks to educate people on what to do to avoid Lassa fever infections. People should know the importance of visiting hospital, whenever they have symptoms.”

Dr. Adebayo Sekumade, President, Association of Resident Doctors, Lagos University Teaching Hospital, said: “The symptomatology includes, fever, weakness and malaise and muscle pain, which mimic other infections, such as malaria and typhoid fever in the mild form of the disease. However, in the serious form of the infection, which occurs in 20 per cent of patients, there is bleeding from the gums, anus and vagina in addition to diarrhoea, vomiting and deafness among others.”

Sekumade enumerated prevention to include good environmental hygiene through proper disposal of wastes, storing of food in tight containers, siting of garbage dump far from homes to eradicate rat population.

He said: “Infected patients should be isolated, while health workers should ensure standard infection prevention and control protocols, which is universal precaution, as well as barrier nursing.

“Treatment is supportive to ensure that patient is not dehydrated. It also includes correction of electrolyte imbalance and treatment for other symptoms. Use of Ribavirin is also important in the early stages of the disease, to prevent its progression.”