Yellow Fever

Occurrence of yellow fever in Africa in 2009

Yellow fever virus

Yellow fever is an infectious disease caused by the flavivirus yellow fever virus. Yellow fever virus causes a serious illness of viscerotropic infection with hemorrhagic syndrome. In the viremic stage, the virus occurs in the liver, bone marrow and kidneys. According to the epidemiology of the occurrence, the urban and jungle forms of yellow fever are distinguished.

• Occurrence: subtropical and tropical Africa, Central and South America;
• source: human or monkeys during viraemia;
• vector: Aedes aegypti mosquito in urban form, Aedes africanus mosquito or Haemagogus mosquito in jungle form;
• incidence: 200 000 cases per year worldwide;
• lethality: 25–50%, 30 000 deaths per year worldwide;
• incubation period: 3–6 days;
• therapy: symptomatic, there is no causal treatment.

Clinical picture

First stage (red)

• chills, fever, lumbar pain;
• fever is usually accompanied by bradycardia (Faget's sign);
• restlessness, patients are generally reddish.

Second stage (yellow)

• worsening of the general condition, face paleness, cyanosis, bleeding from the mucous membranes;
• patient vomits black digested blood (vomito negro);
• manifestation of liver damage – jaundice (may be absent).

Prevention

A live attenuated vaccine is available for prevention (this vaccination is mandatory for entry into some countries). Thanks to vaccination and mosquito control, the urban form of yellow fever has been eradicated in some areas. However, the persistent potential source of human infection is the circulation of the disease in the jungle.

Links

Related articles

• Transmissible infections
• Flaviviruses
• Vaccination

References

• BEDNÁŘ, Marek, et al. Lékařská mikrobiologie. 1. vydání. Praha : Marvil, 1996. 558 s. s. 451.
• BENEŠ, Jiří. Studijní materiály [online]. ©2010. [cit. 15-11-2010]. <http://jirben2.chytrak.cz/materialy/infekceJB.doc>

Reference

Category: Embedded articles Category: Infectious diseases Category: Microbiology