The Federal Government has described as embarrassing, the current outbreak of Lassa fever in the country.
The number of persons infected by the outbreak rose to 86 while 40
deaths had been recorded in the affected states of Bauchi, Nasarawa,
Niger, Taraba, Kano, Rivers, Edo, Plateau, Gombe and Oyo.
The Minister of Health, Prof. Isaac Adewole, spoke on the outbreak of the virus at a press briefing in Abuja Friday.
To curb the spread of the virus, the minister said families of
victims will not be allowed to perform burial rites, adding that the
state will take over the activities.
Adewole said: “Lassa fever is not new to us in Nigeria, what is new
is that it has continued to embarrass us. The first confirmed case was
in 1969, in Lassa village in Borno State. The number of cases peaked in
2012 when 1,723 cases with 112 fatalities were recorded.
“It is also important to highlight that it is not the outbreak that
it is unusual, what is unusual is the large number of deaths recorded so
far and these deaths came largely from three states – Kano, Bauchi and
Niger.
“The three states contributed to about 75 percent of the cases and
deaths. The situation in Niger is worrisome because we had unusual death
dating back to August and only came to light about three to four months
after and that represents a breakdown in disease notification system.
We are trying to strengthen this because deaths even when they are
unusual should be reported and we should not have waited for 35 cases in
Niger before sitting up and that is the worrisome part of it”.
Key facts
- Lassa fever is an acute viral haemorrhagic illness of 1-4 weeks duration that occurs in West Africa.
- The Lassa virus is transmitted to humans via contact with food or household items contaminated with rodent urine or faeces.
- Person-to-person infections and laboratory transmission can also
occur, particularly in hospitals lacking adequate infection prevent and
control measures.
- Lassa fever is known to be endemic in Benin (where it was diagnosed
for the first time in November 2014), Guinea, Liberia, Sierra Leone and
parts of Nigeria, but probably exists in other West African countries as
well.
- The overall case-fatality rate is 1%. Observed case-fatality rate
among patients hospitalized with severe cases of Lassa fever is 15%.
- Early supportive care with rehydration and symptomatic treatment improves survival.
Background
Though first described in the 1950s, the virus causing Lassa disease
was not identified until 1969. The virus is a single-stranded RNA virus
belonging to the virus family
Arenaviridae.
About 80% of people who become infected with Lassa virus have no
symptoms. One in five infections result in severe disease, where the
virus affects several organs such as the liver, spleen and kidneys.
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 known
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.
Because the clinical course of the disease is so variable, detection
of the disease in affected patients has been difficult. However, when
presence of the disease is confirmed in a community, prompt isolation of
affected patients, good infection protection and control practices and
rigorous contact tracing can stop outbreaks.
Symptoms of Lassa fever
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 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 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. Shock, seizures, tremor, disorientation, and coma
may be seen 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 may occur
during recovery.
Death usually occurs within 14 days of onset in fatal cases. The
disease is especially severe late in pregnancy, with maternal death
and/or fetal loss occurring in greater than 80% of cases during the
third trimester.
Transmission
Humans usually become infected with Lassa virus from exposure to
urine or faeces of infected Mastomys rats. Lassa virus may also be
spread between humans through direct contact with the blood, urine,
faeces, or other bodily secretions of a person infected with Lassa
fever. There is no epidemiological evidence supporting airborne spread
between humans. Person-to-person transmission occurs in both community
and health-care settings, where the virus may be spread by contaminated
medical equipment, such as re-used needles. Sexual transmission of Lassa
virus has been reported.
Lassa fever occurs in all age groups and both sexes. Persons at
greatest risk are those living in rural areas where Mastomys are usually
found, especially in communities with poor sanitation or crowded living
conditions. Health workers are at risk if caring for Lassa fever
patients in the absence of proper barrier nursing and infection control
practices.
Diagnosis
Because the symptoms of Lassa fever are so varied and non-specific,
clinical diagnosis is often difficult, especially early in the course of
the disease. Lassa fever is difficult to distinguish from other viral
haemorrhagic fevers such as Ebola virus disease; and many other diseases
that cause fever, including malaria, shigellosis, typhoid fever and
yellow fever.
Definitive diagnosis requires testing that is available only in
specialized laboratories. Laboratory specimens may be hazardous and must
be handled with extreme care. Lassa virus infections can only be
diagnosed definitively in the laboratory using the following tests:
- antibody enzyme-linked immunosorbent assay (ELISA)
- antigen detection tests
- reverse transcriptase polymerase chain reaction (RT-PCR) assay
- virus isolation by cell culture.
Treatment and vaccines
The antiviral drug ribavirin seems to be an effective treatment for
Lassa fever if given early on in the course of clinical illness. There
is no evidence to support the role of ribavirin as post-exposure
prophylactic treatment for Lassa fever.
There is currently no vaccine that protects against Lassa fever.
Prevention and control
Prevention of 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, maintaining clean households and
keeping cats. Because Mastomys are so abundant in endemic areas, it is
not possible to completely eliminate them from the environment. Family
members should always be careful to avoid contact with blood and body
fluids while caring for sick persons.
In health-care settings, staff should always apply standard infection
prevention and control precautions when caring for patients, regardless
of their presumed diagnosis. These include basic hand hygiene,
respiratory hygiene, use of personal protective equipment (to block
splashes or other contact with infected materials), safe injection
practices and safe burial practices.
Health workers caring for patients with suspected or confirmed Lassa
fever should apply extra infection control measures to prevent contact
with the patient’s blood and body fluids and contaminated surfaces or
materials such as clothing and bedding. When in close contact (within 1
metre) of patients with Lassa fever, health-care workers should wear
face protection (a face shield or a medical mask and goggles), a clean,
non-sterile long-sleeved gown, and gloves (sterile gloves for some
procedures).
Laboratory workers are also at risk. Samples taken from humans and
animals for investigation of Lassa virus infection should be handled by
trained staff and processed in suitably equipped laboratories.
On rare occasions, travellers from areas where Lassa fever is endemic
export the disease to other countries. Although malaria, typhoid fever,
and many other tropical infections are much more common, the diagnosis
of Lassa fever should be considered in febrile patients returning from
West Africa, especially if they have had exposures in rural areas or
hospitals in countries where Lassa fever is known to be endemic.
Health-care workers seeing a patient suspected to have Lassa fever
should immediately contact local and national experts for advice and to
arrange for laboratory testing.
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