Question

Which Protista can cause diseases, and which diseases do they cause ? Which host organisms are involved in transmission of those Protista and those protist pathogenic cycles?

Answer 1

Protists tend to remain in environments containing liquid water. Their natural function is to serve as primary producers in the ecosysytem especially in the oceans.

Most protist diseases in humans are caused by animal like protists known as protozoa. Protozoa make humans sick when they become parasites.

Below are the diseases caused by protists along with their host and life cycle.

1. MALARIA

Infectious disease caused by protists of plasmodium genus.Host: Man and female anopheles mosquito.

During a blood meal, a malaria infected anopheles mosquito inoculates sporozoites into human host. Sporozoites infect cells and mature into shizonts which rupture and release merozoits. The parasotes then undergo asexual multiplicationin the erythrocytes.merozoites infect RBCs. There is sexual erythrocytic stage( gametocytes) the gametocytes are ingested by anopheles mosquito during a blood meal. In mosquitos stomach microgametes》zygotes》ookinetes》 invade midgut wall of mosquito》 oocytes》 release sporozoites which enter salivary gland of mosquito.

2. African Sleeping Sickness

Caused by protozoa Trypanosoma brucei

Host: human and tsetse flies

See pic

3. CHAGAS DISEASE

caused by trypanosoma cruzi in south america

Host: Man , dogs , mammals

Vector: triatomines...blood sucking insects

Infected insects take blood meals from humans and their domestic animals and deposit parasite laden feces. Parasites are then transmitted via contact with breaks in skin , mucosal surface or conjunctiva. Transmission also occurs congenitally via blood transfusion by ingestion of food and drink contaminated with feces from infected bugs. See pic

4.GIARDIASIS

Caused by flagellete protozoa Giardia lamblia

Host.: Man

Parasites enter through food or water that has been contaminated by feces of infected people or animals. These parasites attach to lining of small intestines of hosts where they prevent host from fully absorbing nutrients. They also cause diarrhoea, abdominal pain, fever.