OIA1010 PARASITOLOGY

What is parasitology?

The study of organisms (parasites) that live in or on another organism, obtaining food and shelter.

Define obligate parasites and give an example.

Parasites that cannot live without a host, e.g., Trichomonas vaginalis.

What are facultative parasites?

Parasites that can live both freely and parasitically, e.g., Strongyloides species.

Differentiate between definitive, intermediate, and reservoir hosts.

Definitive: harbors adult/sexual stages; Intermediate: larval stages;

Reservoir: carrier host that spreads the infection.

Name the four classes of protozoa.

Sarcodina (e.g., Entamoeba), Mastigophora (e.g., Giardia), Ciliophora (e.g., Balantidium), Sporozoa (e.g., Plasmodium).

What disease is caused by Entamoeba histolytica?

Amoebiasis.

How is Entamoeba histolytica transmitted?

Via ingestion of cysts in contaminated food or water.

What is the infective stage of Plasmodium in humans?

Sporozoite stage.

Describe the life cycle of Plasmodium in mosquitoes.

Sporozoites are injected into humans during a blood meal, develop into merozoites in the liver, and reproduce sexually in the mosquito's midgut.

What are the three main groups of helminths?

Nematodes (roundworms), Cestodes (tapeworms), and Trematodes (flukes).

What is the largest nematode infecting humans?

Ascaris lumbricoides (roundworm).

How is Taenia saginata transmitted to humans?

By ingesting undercooked beef containing larvae.

What disease is caused by Schistosoma species, and how is it transmitted?

Schistosomiasis; transmitted via direct skin penetration in contaminated water.

Give examples of ectoparasites.

Ticks, fleas, lice, mites, and bedbugs.

Do bedbugs transmit diseases?

No, but they cause property loss and inconvenience.

Define mutualism and give an example.

A relationship where both organisms benefit, e.g., gut bacteria in humans.

What is zoonosis?

A disease of animals that can be transmitted to humans, e.g., toxoplasmosis.

How does commensalism differ from parasitism?

In commensalism, one benefits and the other is unaffected; in parasitism, one benefits at the other's expense.

What is the pathology caused by Entamoeba histolytica?

Intestinal damage and possible extraintestinal diseases like liver abscesses.

Why is malaria control challenging in some regions?

Poor socioeconomic conditions and drug resistance.

How does Schistosoma infection occur?

By swimming in water contaminated with larval forms released by snails.

Describe the morphology of Ascaris lumbricoides.

Large roundworm, inhabits the small intestine, with a life cycle involving the lungs and intestine.

What are the morphological features of Taenia saginata?

A flat, segmented tapeworm with a small head and suction disks.

Where do adult Schistosoma reside in humans?

In abdominal veins, depending on the species.

How is Toxoplasma gondii transmitted to humans?

Through undercooked meat, contaminated food, or cat feces.

What symptoms are typical in malaria during the erythrocytic cycle?

Recurrent fever, chills, and fatigue.

How do cestodes affect their hosts?

They absorb nutrients from the intestine, causing weakness and malnutrition.

What is the gold standard for diagnosing malaria?

Microscopic examination of blood smears.

How is Schistosomiasis controlled in endemic areas?

Improved sanitation and snail population control.

What is the lifecycle duration of Ascaris lumbricoides?

Approximately 2 months from egg to adult, with adults living 1-2 years.