LASSA FEVER
Lassa fever is an acute viral hemorrhagic fever caused by the Lassa
fever, a member of the Arenaviridae family. It is an enveloped single-stranded
bisegmented RNA virus. It was first discovered in 1969 in the town of Lassa, in Borno State, Nigeria, in the red scram river valley at the south end of Lake Chad. However, it can be found in other
places, especially in West Africa e.g. Liberia, Guinea, Sierra Leone, and the Central
African Republic, but it is believed that human infections also exist in Democratic Republic of the Congo, Mali and Senegal.
The primary animal host of the Lassa virus is the Natal
Multi-mammate Mouse (Mastomy, nat6alensis), an animal indigenous to most of
sub-haran Africa.
Lassa virus is zoonotic (transmitted from animals), in that it spreads
to man from rodents, specifically multi-mammate rats. This is probably the most
common rodent in equatorial Africa, ubiquitous in human households and eaten as a delicacy in some areas.
In these rats infection is in a persistent asymptomatic state. The virus is
shed in their excreta (urine and faeces), and people become infected by eating
food contaminated with the rat excreta. Infections in human occurs by direct
contact or inhalation of infected body fluids such as urine, blood, saliva etc.
It is also possible to acquire the infection through broken skin or mucous
membranes that are directly exposed to infective material. Transmission from
person to person has also been established, presenting a disease risk for those
living in areas of poor sanitation and health workers managing such cases.
Sexual transmission has not been reported.
Some cases have severe multi-system disease, where the virus affects
several organs in the body, such as the liver, spleen, and kidneys. The
incubation period of Lassa fever ranges from 6 – 21 days. The onset of the
disease 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 may follow. Severe cases may progress
to show facial swelling, fluid in the lung cavity, bleeding from mouth, nose,
vagina or gastrointestinal tract and low blood pressure. Protein may be noted
in the urine. Shock, seizures, tremor, disorientation, and coma may be seen in
the late stages. Deafness occurs in 25% of patients of whom half recover, some
function after 1-3 months. Transient hair loss and gait disturbance may occur
during recovery. In some cases of Lassa fever; it usually lead to death. Death
usually occurs within 14days of onset in fatal cases.
Prevention of Lassa fever centers 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, maintaining clean households and keeping cats. These should
be done because Mastomys are so abundant in endemic areas, it is not possible
to completely eliminate them from the environment. Family members and health
care workers should always be careful to avoid contact with blood and body
fluids while caring for sick persons. Patients suspected to have Lassa fever
should be cared for under specific isolation precautions’, which include the
wearing of protective clothing such as masks, gloves, gowns, and face shields,
and the systematic sterilization of contaminated equipments to avoid infection.
To prevent Lassa fever, contacts between rats and human being should be
avoided. The house and environment should be kept clean always. The environment
should be fumigated periodically. All food & water should be covered
thoroughly and household utensils should be kept clean. All holes and rats
hideouts should be blocked.
Nigeria is once again experiencing an upsurge in reported cases of the deadly
Lassa fever. The latest outbreak, which has claimed no fever than 40 lives, has
affected three hundred and ninety-seven (397) across 12 states of the
federation. Of the reported cases, only eighty-seven (87) have been confirmed
clinically, according to the minister of health, Onyebuchi Chukwu studies
conducted by the global health body, the World Health Organization (WHO) show
that between 300,000 and 500,000 cases of Lassa fever occur annually, from
which 5000 deaths are recorded in the endemic West African States of Sierra
Leone, Guinea, Libera and parts of Nigeria. Although first recognized in 1969
at the town of Lassa in Borno State (from where it derived its name), the disease is endemic in Edo, Nasarawa and Plateau States.
This recent outbreak has exposed Nigeria’s easy susceptibility to preventable, but high mortality diseases. The
devastating effect of Lassa fever is felt year after year. Although the Federal
Ministry of Health has stepped in by providing drugs for the affected States,
more needs to be done, especially in the areas of prevention. Health workers
who should be in the forefront of fighting the epidemic are at greater risk of
getting infected. Out of 40 deaths that have been reported are six Health
Workers – two Doctors and four Nurses. This is enough reason for the government
to also protect their lives through the provision of essential kits such as
gloves and surgical masks needed by them to do their work without unduly
exposing themselves.
In spite of the mortality rate ranging from 15 percent to 45 percent in
some case, the disease could be treated by prompt medical intervention. Even
though it starts with fever, it is always safe for diagnosis for Lassa fever to
be considered in febrile conditions so that treatment could be administered
before the situation gets out of hand. Although there is no vaccine as at now
to prevent Lassa fever, it is heartwarming that many patients who survive it
can build immunity against future attacks.
REFERENCES
Frame JD, Baldwin JM, Gocke DJ, Troup JM (1 July 1970) “Lassa fever, a new virus disease of man from West Africa. Clinical description and
pathological findings”.
“SIGA Passes First Hurdle with Lassa Fever
Antiviral St-193” (Press release).
