The female anopheles mosquito. Image credit

The female anopheles mosquito. Image credit

ZIMSEC O Level Combined Science Notes: Diseases: Cholera

  • Malaria is deadly disease
  • It is caused by (the pathogen) a group of protozoa (single-celled animal) called Plasmodium
  • The protozoa lives in the female Anopheles mosquito and in humans

NB Mosquitos do not cause malaria!

The Lifecycle of the anopheles

The lifecycle of the anopheles mosquito. Image credit

The lifecycle of the anopheles mosquito. Image credit

  • The lifecycle lasts 10-21 days

The Lifecycle of Plasmodium


  • The pathogen infects red blood cells and multiplies in the blood stream
  • This happens every 48 hours causing a fever
  • A female anopheles mosquito bites and feeds on an infected person
  • The pathogen multiplies in the stomach of the mosquito
  • The pathogens move from the stomach to the salivary gland
  • When the mosquito bites again the infected saliva is injected into the victim
  • The diseases has to be properly treated otherwise it will lie dormant only to resurge later

Methods of controlling malaria

  • Prevent the breeding of mosquitos by:
  • spraying their favourite breeding areas,
  • draining/emptying stagnant water
  • Spraying oil/paraffin into the stagnant water
  • Killing adult mosquitoes using insecticides such as DDT
  • Preventing mosquitos from biting people using:
  • Treated/Untreated mosquito nets
  • Covering windows and air vents using wire mesh
  • Wearing thick long sleeved shirts/tops and trousers
  • Use of mosquito repellant jelly
  • Using antimalaria drugs to kill the parasite:
  • Quinine-is effective but cannot kill the parasite in the liver
  • Chloroquine-effective against acute malaria cases and red blood attacks
  • Fancida-useful against chloroquine resistant cases
  • Using prophylactic drugs to prevent and as a precaution against the malaria parasite

To access more topics go to the Combined Science Notes page