Lassa fever, Tropical disease exposed

     There is currently an epidemic of Lassa fever, a viral disease in some parts of Nigeria, West Africa.  

Nine states in the middle belt are affected and a few cases in Rivers state. Coming not long after the Ebola scare, it has gotten many worried and the health authorities on their toes.

There is no need to panic because Lassa fever, unlike Ebola is preventable and curable if diagnosed early. 

We must therefore be on our guard and not confuse it with Malaria, which is very endemic. We must also stay clear of rats!

What is Lassa fever?

Lassa fever is an acute viral illness that occurs in West Africa. The illness was discovered in 1969, during the civil war, when two American missionary nurses from Chicago, died in Nigeria. 

The cause of the illness was found to be the Lassa virus, named after the town in Borno state, Nigeria where the first cases originated.

The virus, a member of the virus family Arenaviridae, is a single-stranded RNA virus and is zoonotic, or animal-borne. In areas of Africa where the disease is endemic. 

Lassa fever is a significant cause of morbidity and mortality.

The main symptoms which appear about three weeks after contact are a fever, headache and tiredness. Very similar symptoms to Malaria.

While Lassa fever is mild or has no observable symptoms in about 80% of people infected with the virus, the remaining 20% have a severe multisystem disease with bleeding, acute renal failure, hepatitis and deafness. 

Lassa fever is also associated with occasional epidemics, during which the case-fatality rate can reach 50%.

Where is Lassa fever found?

Lassa fever is an endemic disease 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.

How many people become infected?

The number of Lassa virus infections per year in West Africa is estimated at 100,000 to 300,000, with approximately 5,000 deaths. 

Unfortunately, such estimates are crude, because surveillance for cases of the disease is not uniformly performed. 

In some areas of Sierra Leone and Liberia, it is known that 10%-16% of people admitted to hospitals have Lassa fever, which indicates the serious impact of the disease on the population of this region.

What animal host is Lassa virus maintained?

The reservoir, or host, of Lassa virus is a rodent known as the "multimammate rat" of the genus Mastomys. 

It is not certain which species of Mastomys are associated with Lassa; however, at least two species carry the virus in Sierra Leone. 

Mastomys rodents breed very frequently, produce large numbers of offspring, and are numerous in the savannas and forests of West, Central, and East Africa. 

In addition, Mastomys generally readily colonize human homes. All these factors together contribute to the relatively efficient spread of Lassa virus from infected rodents to humans.

How do humans get Lassa fever?

There are a number of ways in which the virus may be transmitted, or spread, to humans. 

The Mastomys rodents shed the virus in urine and droppings. Therefore, the virus can be transmitted through direct contact with these materials, through touching objects or eating food contaminated with these materials, or through cuts or sores. 

Mastomys rodents often live in and around homes and scavenge on human food remains or poorly stored food, transmission of this sort is common.

Contact with the virus also may occur when a person inhales tiny particles in the air contaminated with rodent excretions. This is called aerosol or airborne transmission.

Finally, because Mastomys rodents are sometimes consumed as a food source, in most villages in West Africa especially in 

Benue state where it is a delicacy, infection may occur via direct contact when they are caught and prepared for food.

Lassa fever may also spread through person-to-person contact. This type of transmission occurs when a person comes into contact with virus in the blood, tissue, secretions, or excretions of an individual infected with the Lassa virus. 

The virus cannot be spread through casual contact (including skin-to-skin contact without exchange of body fluids).

Person-to-person transmission is common in both village and health care settings, where, along with the above-mentioned modes of transmission, the virus also may be spread in contaminated medical equipment, such as reused needles (this is called nosocomial transmission).

Hospital based Treatment

Ribavirin, an antiviral drug, has been used with success in Lassa fever patients. It has been shown to be most effective when given early in the course of the illness. 

Patients should also receive supportive care consisting of maintenance of appropriate fluid and electrolyte balance, oxygenation and blood pressure, as well as treatment of any other complicating infections with appropriate antibiotics. This is carried out in Isolation wards with barrier nursing care.

Lassa fever is a notifiable zoonotic disease.

Zoonoses still represent significant public health threats, but many of them are not prioritized by health systems at national and international levels. 

They affect hundreds of thousands of people especially in developing countries, although most of them can be prevented.

Superstition

One of the main reasons for late notification and institution of control measures is superstition in the local communities. 

The traditional healers spread the belief that epidemics are caused by evil spirits or gods that have decided to punish the community. 

They claim sacrifices have to be made to appease the gods and threaten anybody who 'tells' with death.

At present there is no vaccine for Lassa fever. There is a vaccine for Yellow Fever, another viral haemorrhagic fever. It is highly recommended and compulsory for visitors to some African countries.

My advice, if you are travelling through the tropics;

1. Consume only hot well cooked meals. If in doubt microwave. 

2. Wash your hands several times a day with soap and water or spirit wipes.

3. Drink boiled, bottled or best, carbonated water.

4. Take Malaria prophylaxis and vaccines for yellow fever and thyphoid which may lower your immunity to viral illness such as Lassa fever.

5. Eat fruits, supplements high in Vitamin C to help strengthen your immunity.

6. Pregnant women, children and the immuno suppressed should avoid visiting the sick in hospital.

7. If you develop high fever, promptly go to the nearest government hospital. Lassa fever is curable.

8. Please do not leave food residue or garbage, uncovered in or around the house.

9. Indomethacin on a piece of bread is an effective rat poison.
10. Have fun safely!

11. A pet cat will hunt down rats!!

12. Please do not eat rats!!!

09-70000-10 to 19 are the Nigeria Center for Disease Control hotlines for Lassa Fever and other disease outbreaks.

Ref: 1.Centre for Disease Control, USA (CDC)

        2. Dr. I Ugwu, Ministry of Health, Niger State

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