Relationship between Lassa fever and Ebola virus disease

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Ebola and Lassa fever belong to the same category. They are called viral haemorrhagic fever. It is an acute sickness, sometimes associated with bleeding, that may be caused by
a number of viruses. Haemorrhagic fever is usually applied to disease caused by Arenaviridae (Lassa fever, Junin and Machupo), Bunyaviridae (Crimean-Congo haemorrhagic fever, Rift Valley Fever, Hantaan haemorrhagic fevers), Filoviridae (Ebola and Marburg) and Flaviviridae (yellow fever, dengue, Omsk haemorrhagic fever, Kyasanur forest disease).
Rodents the cause of lassa fever

 Lassa fever is an acute  haemorrhagic illness caused by Lassa virus, a member of the arenavirus family of viruses. It is transmitted to humans from contacts with food or household items contaminated with rodent excreta.The main animal host of the Lassa virus is the Natal multimammate mouse (Mastomys natalensis), an animal found in most of sub-Saharan Africa. The virus is probably transmitted by contact with the faeces or urine of animals accessing grain stores in residences.  The disease is endemic in  parts of West Africa, including Nigeria.

The disease is also communicable among persons, especially in the hospital environment in the absence of adequate infection control measures. Early diagonosis and prompt treatment will help prevent fatalities.

Symptoms of Lassa Fever

  1. Fever
  2. Red eyes 
  3. Photophobia
  4. Headache
  5. Swollen glands
  6. Oral Ulcers
  7. Muscle aches
  8. Numbness

 Symptoms of Ebola virus Disease

  1. Nausea and vomiting.
  2. Diarrhea (may be bloody)
  3. Red eyes.
  4. Raised rash.
  5. Chest pain and cough.
  6. Stomach pain.
  7. Severe weight loss.
  8. Bleeding, usually from the eyes, and bruising (people near death may bleed from other orifices, such as ears, nose and rectum)

At first sight the symptoms of Lassa are identical to Ebola; there can be bleeding, vomiting and fever. But whereas Ebola is a new outbreak, Lassa fever has been for a long time. According to the WHO, every year it infects from 300,000 to 500,000 people, killing up to 20,000


However, there is one main difference between an outbreak of Ebola and Lassa. Rats cause a Lassa outbreak. The rodents carry the disease into homes and food stores, especially in the dry season running from November to April. Once infected, Lassa can be communicable. Not everyone who catches it becomes seriously ill, but fatality rates have been known to be as high as 70 per cent. It is less easily transmitted than Ebola, but nonetheless patients must still be treated in complete isolation.

 However, there is evidence the Ebola virus can remain in the bodies of survivors after they have recovered from the disease.
This is not the first time Liberia has been declared free of Ebola transmission – the WHO made a similar announcement in May 2015, but the virus returned twice, once in June and then again in November.
 There is evidence that while the Ebola virus may disappear from the bloodstream of survivors pretty quickly; it can survive in “batches” in the body. For example, it can survive in men’s semen for seven to nine months and in the eye for two months after recovery.

 For a country to be declared free of Ebola, it must achieve 42 days (two 21-day incubation cycles of the virus) since the last confirmed patient tests negative for the disease two times.

 WHO’s Special Representative for the Ebola Response, Dr. Bruce Aylward, said that the epidemic is in a critical period as countries move from managing infected patients to managing the risk of new infections.
He noted that the risk of new infections is gradually reducing as the virus clears from the survivor population, but “we still anticipate more flare-ups and must be prepared for them.”
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