Ch.5 the protozoa.
Protozoa:- Single-celled animals.- Some can infect humans opportunistically. They continue to multiply in theirhost until controlled by its immune response or by treatment.- May cause disease directly (e.g. rupture of RBC), but more often the pathologyis caused by the host’s response.Infect body tissues and organs as:- Intracellular parasites, RBC, macrophages; Obtain nutrients from the host cellby direct uptake or by ingestion of cytoplasm.- Extracellular parasites in the blood, intestine or genitourinary system; feed bydirect nutrient uptake or by ingestion of host cells;Protozoa reproduction is usually asexual, by binary or multiple division of growing stagesProtozoa have evolved many sophisticated strategies to avoid host responses.Extracellular species evade immune recognition of their plasma membrane. Theinterface is the parasite’s plasma membrane, and examples of strategies toavoid immune recognition of this surface e.g. undergo repeated antigenicvariation of surface antigens.Infections routes:- By ingestion, contaminated food or water with transmission stages such ascysts;- Insect vectors;- mother in utero.
Ch. 6. Helminths and arthropods.
Groups of parasitic worms. Three main groups : 1.) tapeworms (cestoda), 2.)the flukes (Trematoda or Digenea) and 3.) the roundworms (nematoda). Firsttwo belonging to the Platyhelminths or flatworms, the third include in a separatephylum. Platyhelminths have flattened bodies with muscular suckers and/orhooks for attachment Nematodes have long cylindrical bodies and generally lackspecialized attachment organs. Sources of food are blood and tissue fluid.Transmission occurs in four distinct ways: