Lassa fever or Lassa hemorrhagic fever (LHF) is
an acute viral hemorrhagic fever caused by the
Lassa virus and first described in 1969 in the town of
Lassa, in Borno State, Nigeria.[1] Lassa fever is a
member of the arenaviridae virus family. Similar to
Ebola,[2] clinical cases of the disease had been
known for over a decade but had not been
connected with a viral pathogen. The infection is
endemic in West African countries, resulting in
300,000–500,000 cases annually, causing
approximately 5,000 deaths.[3] Outbreaks of the
disease have been observed in Nigeria, Liberia,
Sierra Leone, Guinea, 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 Multimammate Mouse (Mastomys
natalensis), an animal indigenous to most of Sub-
Saharan Africa.[4] The virus is probably transmitted
by contact with the feces or urine of animals
accessing grain stores in residences.[4] Given its
high rate of incidence, Lassa fever has become a
major problem in the African region.[5][6]
Signs and symptoms
In 80% of cases, the disease is asymptomatic, but in
the remaining 20%, it takes a complicated course. It
is estimated that the virus is responsible for about
5,000 deaths annually. The fever accounts for up to
one third of deaths in hospitals within the affected
regions and 10 to 16% of total
cases.[citation needed]
After an incubation period of six to twenty-one days,
an acute illness with multiorgan involvement
develops. Non-specific symptoms include fever,
facial swelling, and muscle fatigue, as well as
conjunctivitis and mucosal bleeding. The other
symptoms arising from the affected organs are:
Gastrointestinal tract
Nausea
Vomiting (bloody)
Diarrhea (bloody)
Stomach ache
Constipation
Dysphagia (difficulty swallowing)
Hepatitis
Cardiovascular system
Pericarditis
Hypertension
Hypotension
Tachycardia (abnormally high heart rate)
Respiratory tract
Cough
Chest pain
Dyspnoea
Pharyngitis
Pleuritis
Nervous system
Encephalitis
Meningitis
Unilateral or bilateral hearing deficit
Seizures
Clinically, Lassa fever infections are difficult to
distinguish from other viral hemorrhagic fevers
such as Ebola and Marburg, and from more
common febrile illnesses such as malaria.