Though first described in the
1950s, the virus causing Lassa disease was not identified until 1969 when it
was fully discovered in Nigeria, specifically in a village called ‘Lassa’ in
Borno State; suffice to say that the virus was named after the said village.
Lassa fever is an infectious
disease caused by a virus known as ‘Lassa virus’, which is a single-stranded
Ribonucleic Acid (RNA) virus belonging to the virus family Arenaviridae. Lassa
fever is a zoonotic disease meaning that humans become infected from contact
with infected animals. The animal reservoir or host of Lassa virus is a rodent
of the genus Mastomys commonly referred to as the ‘multimammate rat’. Mastomys
rats infected with Lassa virus do not become ill, but they can shed the virus
in their urine and faeces.
Thus, Lassa fever is an acute
viral haemorrhagic illness of 1-4 weeks duration that occurs typically in West
Africa. The Lassa virus is transmitted to humans via contact with food or
household items contaminated with urine or faeces of infected rodents such as flying
squirrels, rats, rabbits, among others. Person-to-person infections and
laboratory transmission are equally possible, particularly in hospitals lacking
adequate infection prevention and control measures.
Currently, Lassa fever is known to be endemic in Benin Republic where it
was diagnosed for the first time in November 2014, Guinea, Liberia, Sierra
Leone and parts of Nigeria, and probably exists in other West African countries
as well. According to the World Health Organization (WHO), the overall
case-fatality rate is 1%; observed case-fatality rate among patients
hospitalized with severe incidents of the virus is 15%.
About 80% of people who become
infected with Lassa virus have no symptoms. Because the clinical course of the
disease is so variable, its detection in infected patients has been very
difficult. It is worth noting that one in five infections result in severe
disease, where the virus affects several essential organs to include the liver,
spleen and kidneys. It has been proven that when presence of the disease is
confirmed in a certain community, prompt isolation of affected or suspected
persons, good infection protection and control practices, as well as rigorous
contact tracing can stop the outbreak.
The incubation period of Lassa fever ranges from 6–21 days. The onset of
the disease when it is symptomatic is usually gradual starting with fever,
general body weakness, and malaise. After a few days, headache, sore-throat,
muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain
may follow suit. In severe cases, facial swelling, fluid in the lung cavity,
bleeding from the mouth, nose, vagina or gastrointestinal tract, and low blood
pressure may develop. Protein may be noted in the urine in some cases. More so,
shock, seizures, tremor, disorientation, and coma might be observed in the
later stages.
Deafness occurs in 25% of patients
who survive the disease; in half of these cases, hearing returns partially
after 1-3 months. Transient hair loss and gait disturbance might set in during
recovery stage. Death often takes place within 14 days of onset in fatal
incidents. The disease is mostly severe in pregnancy, with maternal mortality
and/or foetal loss occurring in greater than 80% of incidents during the third
trimester.
Lassa virus can also be spread between humans through direct contact
with the blood, urine, faeces, or other bodily secretions of a person infected
with the virus. We must note that there’s no epidemiological evidence
supporting airborne transmission between humans; but the virus can be spread
via sharing of medical equipment such as needles as well as through sexual
acts.
Since Lassa fever can be hardly distinguished
from other haemorrhagic fevers like Ebola virus disease and many other diseases
that cause fever including malaria, typhoid, yellow fever, shigellosis, its
infections can only be diagnosed definitively in the laboratory using the
following tests: antibody Enzyme-Linked Immunosorbent Assay (ELISA), virus
isolation by cell culture, Reverse Transcriptase Polymerase Chain Reaction
(RT-PCR) assay, and/or antigen detection tests.
The antiviral drug, Ribavirin seems to be an effective treatment for
Lassa fever if given early in the course of clinical illness. There is no proof
to support the role of ribavirin as post-exposure prophy lactic treatment for
Lassa fever. Currently, there’s no vaccine that protects the body against Lassa
fever.
In a critical situation like this, we cannot ignore the obvious fact
that prevention is far better than cure. Since Lassa fever is yet to boast of a
vaccine, the most reliable preventive measure remains total abstinence or
optimum utilization of avoidance approach. The general public, particularly our
young ones, rather than posting comic commentaries on various social media as
regards the epidemic ought to be meant to acknowledge this fact headlong
without much ado. It’s baffling to realize that most people are making fun of
an epidemic that have claimed several lives, thus all hands are expected to be
on deck towards orientating the populace.
In view of the above assertion, it’s worthy to note that measures such
as sustenance of community hygiene to discourage rodents from entering living
places, storing grain and other foodstuffs in rodent-proof containers,
disposing of garbage far from homes, maintaining clean households and keeping
cats away from our consumables, are mostly required. Similarly, family members
should always be careful to avoid contact with blood and other bodily fluids
while caring for sick relatives.
People must also desist from
consuming raw foods, or intake of foods and waters that are not properly boiled
or cooked as the case may be. In the same spirit, any fruit or vegetable gotten
from the gardens that have already been pierced or bitten by animals, probably
squirrels, should be thoroughly washed with salt and water, and thereafter
ought to be well heated before they would be consumed.
On their part, health workers caring for patients with suspected or
confirmed Lassa fever should apply extra infection control measures to prevent
contact with the carrier’s blood and other bodily fluids as well as
contaminated surfaces or materials such as clothing and bedding. When in close
contact with Lassa fever patients, health care attendants should endeavour to
wear face mask cum goggles, a clean long-sleeved gown, and gloves. Laboratory
technicians are also advised to properly handle samples taken from humans or
animals for investigation of Lassa virus infection and ought to be processed in
suitably equipped laboratories.
More so, travellers coming from other countries especially West African nations
should be quarantined on arrival at the airports and therein adequately tested
for Lassa fever as well as other related infections. Among all, we shouldn’t be
cautious of only rats regarding the primary source/host of the virus as it is
presently witnessed; rather we must endeavour to secure our edibles from other
forms of rodent especially the ones within our reach to include squirrels and
mice as well as cats which are invariably kept as pets by several families. To
before warned is to before armed. Think about it!
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