Yellow Fever

Table of Contents

Disease Information

Yellow fever is a mosquito-borne viral illness.

Overview

Report Immediately by Phone

Responsibilities

  • Hospital: Report immediately by phone
  • Lab: Report immediately by phone
  • Physician: Report immediately by phone
  • Local Public Health Agency (LPHA): Follow-up required.  Iowa Department of Public Health will lead the follow-up investigation.

Iowa HHS
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698

A. Agent

Yellow fever is a mosquito-borne viral illness. It is caused by the yellow fever virus, which is in the genus Flavivirus and family Flaviviridae.

B. Clinical Description

Many cases of yellow fever are so mild they go undetected. Yellow fever is only known to occur in Africa and South and Central America.

Symptoms: In typical cases of recognized illness, sudden onset of fever, chills, headache, backache, generalized muscle pain, prostration, nausea and vomiting, jaundice, and albuminuria (the presence of protein in the urine) may occur. Most infections resolve at this stage.

Complications: In more severe cases of illness, after a brief remission of hours to a day, there is progression to liver and kidney failure and to hemorrhagic symptoms, including nosebleeds, bleeding gums, bloody vomiting and bloody stools. Twenty to 50% of severe cases with jaundice are fatal. The overall case-fatality rate is 20-50 percent. Lifetime immunity follows yellow fever recovery.

C. Reservoirs

Monkeys are the primary reservoirs in forested areas of Africa and South America. Humans and Aedes aegypti mosquitoes are involved in the infective cycle in urban areas.

D. Modes of Transmission

Yellow fever has two different transmission cycles that affect humans, the urban cycle and the jungle cycle.

  • Urban cycle: The virus is transmitted among humans by the bite of an infective house-dwelling Aedes aegypti mosquito. Monkeys play little or no role as a reservoir.
  • Jungle cycle: Several species of mosquitoes are vectors and transmit virus from monkey to monkey. Humans are involved in the jungle cycle accidentally if bitten by infected mosquitoes. In South America, sporadic infection of humans occurs almost exclusively in forestry and agricultural workers through occupational exposure, however outbreaks can and do occur. Direct person-to-person spread of yellow fever does not occur.

E. Incubation Period

The incubation period for yellow fever is 3 - 6 days.

F. Period of Communicability or Infectious Period

Yellow fever is not transmitted from person-to-person. The blood of patients is infective for mosquitoes from shortly before onset of fever until 3 - 5 days of illness. The incubation period in Aedes aegypti mosquitoes is commonly 9 - 12 days at the usual tropical temperatures. Once infected, mosquitoes remain so for life.

G. Epidemiology

Yellow fever is now endemic only to certain regions of South and Central America and Africa.  Any cases in Iowa are likely due to recent travel abroad.

H. Bioterrorism Potential

None.

I. Additional Information

CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)

Fact Sheets and Forms

References

American Academy of Pediatrics. 2003 Red Book: Report of the Committee on Infectious Diseases, 26th Edition. Illinois, American Academy of Pediatrics, 2003.

Yellow Fever-Disease and Vaccine, Division of Vector-Borne infectious diseases: www.cdc.gov/yellowfever/

Evans, Alfred. Viral Infections of Humans, Epidemiology and Control, Second Edition. New York, Plenum Medical Book Company, 1984.

Heymann, D.L., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.

Mandell, G., Bennett, J., Dolin, R., eds. Principles and Practice of Infectious Diseases, Fourth Edition. New York, Churchill Livingstone Inc., 1995.