Malaria
Malaria has had a LONG history
This presentation covers the following:
Let me paint a picture with a very broad brush -- parasitic infections are a relatively minor problem in North America because:
But what happens if one of those attributes is NOT true?
There are 4 species of Plasmodium which infect humans and cause malaria.
The life cycles of these 4 species are virtually identical:
Exoerythrocytic (liver) stage is virtually symptomless
Symptoms & pathology are associated with the erythrocytic stage.
Once established, the parasite cell ingests hemoglobin and enlarges to form a “schizont”
The schizont ruptures, and the next generation of merozoites is released to invade new RBC’s.
Most symptoms are associated with the synchronous rupturing of erythrocytes:
Anemia results from massive destruction of erythrocytes
Falciparum malaria is always serious, and is easily fatal
Cerebral malaria on left, normal brain on right: Slate-grey color is the result of hemozoin deposition. Tiny hemorrhages in white matter are visible, and there is considerable swelling.
Blackwater fever - normal urine is in bottle A, blackwater urine in B, and diluted blackwater urine in C.
In the middle of a chill/fever episode (aka paroxysm), victim may be delirious, and will have ashen gray skin.
Eventually, merozoites invading erythrocytes follow a different developmental path to become gametocytes, as in this P. falciparum gametocyte.
Sexual reproduction occurs in the mosquito
When fully developed, the oocyst may contain thousands of infective sporozoites, which migrate to the salivary gland.
We are now observing drug-resistant strains of Plasmodium being transmitted by insecticide-resistant strains of mosquitos.
Prophylactics are suggested for people visiting malarial regions
There has been concern that global warming has altered the distribution of malaria in tropical highlands.
Populations living in malarious regions have adapted to the disease by possessing a number of genes which confer resistance.
Duffy blood groups confer resistance to vivax malaria.
Other genetic conditions which confer resistance to malaria:
Since the malarial parasites have developed resistance to drugs, there is considerable incentive for developing vaccines.
From Schmidt & Roberts’ Foundations of Parasitology, ed. 6:
Email: seisen
Home Page: http://www.cbu.edu/~seisen/
Other information: Malaria: Life cycle, pathology, genetics, status of vaccines