LASSA FEVER: WHAT YOU SHOULD KNOW
Lassa fever is an acute febrile illness which can progress to bleeding from different parts of the body and ultimately leading to death if not treated urgently and aggressively.
Even though there had been cases of the infection in medical literature as far back as in the 50s, the illness was discovered in 1969 when two missionary nurses died in Nigeria, West Africa. The cause of the illness was found to be Lassa virus, named after the town in Nigeria where the first case originated. So the name LASSA FEVER was coined from ‘’Lassa’’ which happens to be the village in Bornu State, Nigeria where the virus was discovered and ‘’fever’’ which is characteristics of the disease and usually the first presenting complain of an infected person. It is estimated that the number of Lassa virus infections per year is between 100,000 to 300,000, with about 5,000 deaths.
Lassa fever is not limited to Nigeria alone, it is known to be present in the West African sub-region. Lassa fever is endemic (occur constantly) in portions of West Africa. It is recognized in Guinea, Liberia, Sierra Leone, as well as Nigeria. However, because the rodent species which carry the virus are found throughout West Africa, the actual geographic range of the disease may extend to other countries in the region. Subsequently, the disease has been reported in countries like Ghana, Mali, Burkina Faso and Côte d’Ivoire.
WHAT CAUSES LASSA FEVER
The virus which causes Lassa fever is similar to Ebola virus with little differences. Its host and reservoir is the multi-mammate rat called ‘’Mastomys Natalensis’’. Once the rat is infected with the virus, the virus reproduce and continue to live inside the rat for as long as the rat exists. The virus can be found in all the secretions (blood, faeces urine, saliva etc.) of the rat. The rat exhibits some unique qualities; it breed very frequently, produce large numbers of offspring, it is found in the forests and savannah of West, East and Central Africa, it readily colonize human homes, and it has 24 breasts. All these factors together contribute to the relatively efficient spread of Lassa virus from infected rodents to humans.
HOW DO WE BECOME INFECTED
We can be infected with the virus through two different routes
When our mucus membranes (in the eyes, nose, mouth) or a break in our skin comes in contact either directly or indirectly with the infected rat and its secretions. This can occur through any of these means
i touching objects contaminated with the infected rat’s secretions.
ii Eating food contaminated with these secretions or eating an infected rat. Because Mastomys rodents often live in and around homes and scavenge on human food remains or poorly stored food, transmission of this sort is common.
iii Contact with the virus may also occur when a person inhales tiny particles in the air contaminated with rodent excretions. This is called aerosol or airborne transmission. This can occur while sweeping.
When our mucus membranes or a break in the skin comes in contact either directly or indirectly with all forms of secretions (sweat, saliva, semen, blood, tears, urine, faeces, vagina secretions etc.) of an infected person. This is called person-person transmission. This tends to be common in overcrowded places, areas of poor hygiene, hospitals and among relatives and other care-givers of an infected person. Also when one come in contact with contaminated medical equipment.
It is worth to note at this point that the virus cannot be contacted through casual touching, shaking hands or hugging an infected person as long as one does not come in contact with any of his/her body secretions. However, this is not advisable in most cases.
WHAT ARE THE SYMPTOMS
There are no specific symptoms of Lassa fever. In most cases, the symptoms are non-specific and may be misdiagnosed as malaria, typhoid or other febrile illness. The interval between the time of being infected and the occurrence of the symptoms is called incubation periods and it is about 6-21 days.
Also, in 80% of infected cases, the infection is mild or asymptomatic. But the remaining 20% can have severe multi-system disease affecting several organs like liver, kidney, spleen, heart and the brain.
The onset of the infection is gradual, starting with a fever that is not responding to the conventional antimalarial and antibiotics. Others include general weakness, feeling of unwell, joint ache, headache, sore throat, back ache, abdominal pain and cough. This can progress to bleeding from different parts like stooling blood, vomiting blood, coughing blood and urinating blood, bleeding from the nose, eyes, skin, vagina and other parts of the body. Later on, the disease can progress to confusion, agitation, convulsion, coma and ultimately death.
Unlike in the case of Ebola, there is cure for Lassa fever provided the patient present early. Lassa fever can be successfully treated with the drug called RIBAVIRIN. There are other supportive measures that will be given to the patient depending on the presentation.
It is worth to note that despite treatment, about 15%-20% of patients hospitalized for Lassa fever die from the illness. During epidemics, it can be as high as 50%. Pregnant women are the most affected and it is estimated that about 80-90% of pregnant women and/or the unborn child dies when the infection in the final stage of pregnancy.
Perhaps this is the most important aspect of this write-up. Lassa fever can be prevented through the following:
Avoiding contact between rats and human beings
Keeping our environment and house clean
Proper storage of our foods and other consumables in rodent proof container
Preparing our food in a clean environment
Avoid eating rodents
Keeping cats at home so as to scare away rodents
Regular hand washing
Avoid contact with an infected person
Disposing waste far from home
Health workers should observe UNIVERSAL PRECAUTIONS when attending to patient. The use of Personal Protective Equipment (PPE) should be observed.
Blocking all routes via which rats enter the house.
Lassa fever is a febrile illness which is endemic in West Africa. It can be contacted through direct or indirect contact with the multi-mammate rats. It can also be contacted through direct or indirect contact with all the secretions of an infected human beings. However, the good news is that it can be treated provided the infected person presents early to the hospital. Primary prevention through avoiding contact with rats and infected person remains the gold standard in controlling the infection.
If you need help or want to report a case or need to clarify if a sick person has Lassa fever, or simply want to know more about Lassa fever, kindly call the following numbers
National Centre for Disease Control – 09-70000-10, 09-70000-11 to 09-70000-19.
Federal Ministry of Health – 08093810105, 08163215251, 08031571667, 08135050005.
DR SALAWU A.A
MB;BS (Lagos), MPH scholar (London)
Head Medical Corps, MSSN Lagos State