Lassa Fever

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Lassa fever is a viral haemorrhagic disease.

Cause

  • Lassa fever virus from the arena virus family. Transmission is from an infected rat to human or human to human.

Note See Manual on Prevention and Control of Lassa Fever for Peripheral Health Unit Staff for more details

Signs and symptoms

The clinical signs of  Lassa Fever are non-specific

  • Onset is gradual and its symptoms are similar to those of many other conditions such as common cold, malaria, typhoid and yellow fever, illness can be categorized into four stages

Stage 1:

      On set

  • High fever greater than 38°C
  • General weakness and malaise
  • Headache
  • Muscle and joint pain
  • Cough, sneezing

Stage 2

4-7 days after onset

  • Sore throat (with white exudative patches) – very common
  • Persistent headache
  • Generalized body pain
  • Abdominal pain
  • Conjunctivitis (red eyes)
  • Nausea and vomiting
  • Diarrhoea
  • Hypotension (systolic BP less than 100)
  • Anaemia
  • Productive cough

Stage 3

7-14 days after onset

  • Swollen neck and face
  • Convulsion (due to high fever)
  • Confusion/disorientation
  • Mucosal bleeding from the gums (mouth) nose and eyes

Stage 4

      More than 14 days after onset

  • Convulsion
  • Bleeding (from the vagina, rectum, haematemesis and haemoptysis)
  • Coma
  • Respiratory distress
  • Renal failure
  • Death (approximately 20% of cases not treated or treated late)

Diagnosis

  • Clinical diagnosis is often difficult, especially early in the course of the disease. It is difficult to distinguish from other viral hemorrhagic fevers such as Ebola virus and other infections such as malaria, shigellosis, typhoid fever and yellow fever.
  • Definitive diagnosis requires testing that is available only in reference laboratories using the following tests
    • Reverse transcriptase polymerase chain reaction (RT-PCR) assay
    • Antibody enzyme-linked immunosorbent assay (ELISA)
    • Antigen detection tests
    • Virus isolation by cell culture.

Non-pharmacological treatment

General principles

  • Isolate patient
  • Observe complete barrier nursing (antiseptic hand washing with chlorine solution and or antiseptic soap, use protective personal equipment)
  • Inform the DHMT through the district surveillance officer(s)
  • Refer with minimal delay
  • Trace all contacts

Pharmacological treatment

Ribavirin IV

30mg/kg body weight as a single loading dose

FOLLOWED BY

16mg/kg intravenous every 6 hours for 4 days

THEN

8mg/kg every 8 hours for 6 additional days.

Note Ribavirin is most effective within the first 6 days of illness

Prevention

  • For close contacts, give oral ribavirin 500mg two times a day for 7 days.
  • Healthcare workers caring for Lassa fever patients should apply standard infection prevention and control precautions: wear a face shield or a medical mask and goggles, a clean, non-sterile long-sleeved gown, and gloves.

Reporting

  • Lassa Fever is a notifiable disease. All cases must be reported to the District Health Management Team through the district surveillance officers and Program Manager (Lassa Fever Program in Kenema).