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Protozoa- a single celled organism that can only divide when inside a host organism

Vector- any living carrier that transmits an infectious agent to host.


Pathogenesis of malaria

The beginning of malaria is caused by the protozoan plasmodium. This has four different species which infect humans causing diseases and in some cases mortality. The four species are:


  • P. falciparum
  • P. vivax
  • P. malariae
  • P. ovale

The pathogenesis of the human life cycle of malaria takes part in two stages- the exoerythrocytic and the erythrocytic stages.

The exoerythrocytic stage begins with the vector transmitting malaria to the host through the skin. The vector that does so is the female anopheline mosquito. When feeding from a potential host, the mosquito transmits sporozoites into the blood stream. These then move to the liver where they begin to reproduce and mature into hepatic schizonts.

The erythrocytic stage then beings when the hepatic schizonts break and merozoites are released into the circulation which then infects the red blood cells in the body. These then develop into trophozoites which feed on the red blood cells, multiply and develop into schizonts which break and release even more merozoites into the circulation. The merozoites can then infect more parts of the body.



Symptoms can take up 13-17 days after infection to appear. The two categories of malaria symptoms are uncomplicated malaria and severe malaria. The early uncomplicated symptoms of malaria are:


  • Fever
  • Sweating and Chills
  • Cough
  • Headache
  • Diarrhoea

Severe malaria can occur which can cause breathing problems, liver failure fits and infection of the brains blood vessels. If this happens it can send the sufferer into a coma and lead to mortality.



Malaria is mainly diagnosed with the a Wright or Giemsa- stained thick and thin blood smear by microscopy to see if the red blood cells show traces of the parasite.

(Ashley et al., 2006; Bottone, 2006)

True-False Question
Please complete this short true or false quiz after reading this section to test your knowledge on malaria

1. There are 3 stages of the human malaria life cycle

True False

2. The vector that infects the host with malaria is the female anopheline mosquito

True False

3. Symptoms of malaria take 20 days to appear in the host

True False