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|Incubation Periods
| Notifiable Diseases UK
Body fluids contain virus and cross contamination is possible so isolation needed.
About
- Viral haemorrhagic fever due to a Flavivirus spread by mosquito
- Endemic in Monkeys in South America and West and Central Africa
- Spread amongst humans by Aedes aegypti
- Spread amongst primates Aedes Africanus in Africa
- Spread amongst primates Haemagogus in Americas
Aetiology
- Infection when these mosquitos come into contact with man
- Rural cycle of spread amongst primates and urban cycle involving man
- Main death toll is in Sub-saharan Africa and South America
- Human beings can also serve as the viraemic host for mosquito infection
- It is not seen in Asia
Clinical
- Mosquito feeds on humans usually during daylight hours
- Febrile illness comes on after IP 3-6 days after a bite
- Myalgia, reddened conjunctiva, bradycardia
- Jaundice appears on day 2-3
- Abdominal pain, drowsiness and worsening nausea and vomiting
- Can develop DIC and liver disease with haemorrhage from the mucosa
- Shock and multiorgan failure, renal failure and coma
Differentials
- Malaria, Typhoid, Viral hepatitis
- Leptospirosis, Haemorrhagic fevers
- Aflatoxin poisoning
Investigations
- FBC: ↑ WCC may be seen
- Virus isolated from blood in first 24 hours
- Liver histology (postmortem) - Councilman bodies and midzonal necrosis
- Viral serology ↑ IgM or ↑ x4 IgG
- Coagulation screen - may identify DIC
Management
- ABC, Supportive. Transfusion of red cells, full circulatory support, plasma expanders and renal replacement therapy where indicated.
- Body fluids contain virus and cross-contamination is possible so isolation needed. Mortality is 15%.
- Vaccination programmes - live attenuated which may cause a mild illness. Cannot be given to the immunosuppressed.
References
- Mosquitoes and Their Control. Norbert Becker et al. Springer, 2010