Microbiology and Immunology

Yellow fever WORLD OF MICROBIOLOGY AND IMMUNOLOGY

614

•

large epidemic. The infection is spread exclusively by mos-

quitoes feeding on one person then on another. Control of

these epidemicsconcentrates on eradicating the mosquito

populations.

Treatment for yellow fever consists primarily of keep-

ing the patient hydrated and comfortable. Prevention of the

infection, via vaccination, is the most prudent course of action.

The current vaccine (which consists of living but weakened

virus) is safe and provides long-lasting immunity. While side

effects are possible, the risks of not vaccinating far outweigh

the risk of the adverse vaccine reactions. For a vaccination

campaign to be effective, over 80% of the people in a suspect

region need to be vaccinated. Unfortunately few countries in

Africa have achieved this level of coverage. Another course of

action is the control of mosquito populations, typically by

spraying with a compound that is toxic to mosquito larvae dur-

ing breeding season. Once again, this coverage must be exten-

sive to be successful. Breeding areas missed during spraying

ensure the re-emergence of mosquitoes and, hence, of the yel-

low fever virus.

See alsoTransmission of pathogens; Zoonoses

womi_Y 5/7/03 9:15 AM Page 614