In the face of this, health experts have advised that families, communities and individuals protect themselves by avoiding foods contaminated by rats and keeping their environment clean.

People should not allow bushes to grow in their environment to deter rodents carrying the virus.

Dr. Modupe Akinyinka, Senior lecturer and Consultant Public Health Physician at Department of Community Health and Primary Health Care Lagos State University College of Medicine (LASUCOM), Ikeja, Lagos, said Lassa fever occurs in all age groups and both sexes.

However, persons at greatest risk are those living in rural areas or anywhere with rats.

She said: “Signs and symptoms of Lassa fever include fever, general weakness, and malaise.

After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough and abdominal pain may follow.

In severe cases, there are facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract.

“Lassa fever is caused by the Lassa fever virus. It is transmitted by the intake of food contaminated with faeces or urine of infected rats (mastomys) and contact with body fluids of infected persons.

Transmission of Lassa virus to humans occurs most commonly through ingestion or inhalation.

The rodents shed the virus in urine and droppings and direct contact with these materials, through touching objects.

“People should keep rats away form the house, and keep food covered always. They should also keep their environments clean.

All sick persons should quickly go for treatment in hospital. Health workers should adhere strictly to universal precautions. Treatment is available with an anti-viral drug and other supportive treatments.”

Dr. Omojowolo Olubunmi, a Consultant Neurologist and Former President, Association of Resident Doctors at Lagos University Teaching Hospital (LUTH) Idi-Araba, Lagos, said about 80 per cent of human infections are without symptoms, while the remaining cases have severe multiple organ diseases, where the virus affects several organs in the body, such as the liver, spleen and kidneys.

He said: “Lassa fever is a significant cause of severe illness and death. Transmission of the virus also occurs in health facilities, where infection prevention and control practices are not observed. Person to person transmission also occurs, most especially when a person comes in contact with the virus in the blood, tissue, secretions or excrements of an infected individual.

“Protein may be noted in the urine. Shock, seizures, tremor, disorientation and coma may be seen in the later stages. Deafness occurs in 25 percent of patients who survive the disease. In half of these cases, hearing returns partially after one to three months. Transient hair loss and gait disturbance may occur during recovery, and patients may die from shock.”

Olubunmi explained that Lassa virus infections can only be diagnosed definitively in a virology laboratory, using the following tests: the reverse transcriptase polymerase chain reaction RT-PCR assay, testing for IgM, antigen detection tests and virus isolation by cell culture.

“The only known specific treatment for Lassa fever is Ribavirin, which may be effective if given within the first six days of illness. It should be given intravenously for ten days.

Supportive treatment should include, paracetamol, vitamin K (phytamenadione), heamacel, Ringers lactate, anti-malaria and antibiotics. If patient is severely anaemic, consider transfusion. There is currently no vaccine that protects against Lassa fever,” he explained.

Olubunmi noted that proactive measures to contain Lassa fever relies on promoting good community hygiene” to discourage rodents from entering homes. Effective measures include storing grain and other foodstuffs in rodent-proof containers, disposing of garbage far from the home and maintaining clean households.

He said: “In healthcare settings, prevention is by standard precautions, where all blood and body fluids are considered potentially infectious. Standard precautions are applied to all patients at all times, and in all healthcare settings. These include hand hygiene, use of appropriate personal protective equipment (PPE), waste disposal, cleaning and disinfection of medical equipment and environment, safe injection practices.”

Consultant Virologist, Prof. Sunday Aremu Omilabu explained that the rodents that transmit the virus ordinarily live in bushes, but during the dry season, they run into houses for protection and live with humans, where they deposit excreta on floors, tables, beds and food items.

He said: “The foods that are contaminated by the rodents include, garri, yam, rice and beans among others. So, people should cover their foods properly, and avoid taking soaked garri that is not well covered. People should also avoid eating left over foods without warming them properly.

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

“Nosocomial transmission occurs as a result of treatment in a hospital and outbreaks in healthcare facilities in endemic areas, which represent; a significant burden on the healthcare system.

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

“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 to 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 such other countries as Central African Republic, Ghana, Mali, Ivory Coast, Togo, Benin and Cameroon.”

Omilabu urged government to provide health educations among the people by creating radio and television jingles, including other networks to educate people on what to do to avoid Lassa fever infections. It is also essential to let people know the importance of visiting hospital whenever they have symptoms.