1. Differentiate biological vector from mechanical vector. (4 marks)
2. Mention two parasitic diseases transmitted by mosquitoes. (2 marks)
3. Explain the genetic method of control mosquitoes as disease vectors. (2 marks)
4. Mention any two mechanical vectors. (2 marks)
5. Explain how Entamoeba histolytica would cause lysis of the host cells? (4 marks)
6. Define giardiasis? (1 mark)
7. Mention three types of Leishmaniasis. (3 marks)
8. What specimen is recommended for detection of babesia trophozoites and merozoites? (1
mark)
9. Which parasitic disease has symptoms similar with that of malaria and is commonly
misdiagnosed for malaria disease? (1 mark)
10. Mention any three species of malaria parasites. (3 marks)
11. Give a plasmodium species responsible for malaria relapses. (1 marks)
12. What is the sexual form of plasmodium species responsible for malaria
relapses? (1 mark)
13. What is the main mode of transmission for Plasmodium falciparum? (1 mark)
14. Describe the life cycle of Plasmodium vivax. (4 marks)
15. What is the primary mode of transmission for Trypanosoma cruzi? (1 mark)
16. Explain how Trypanosoma cruzi causes Chagas disease in humans. (4 marks)
17. Mention two diseases caused by the parasitic protozoan Toxoplasma gondii. (2 marks)
18. How is Toxoplasma gondii transmitted from animals to humans? (2 marks)
19. Describe the life cycle of the parasitic helminth Taenia solium. (4 marks)
20. What is the primary mode of transmission for Schistosoma mansoni? (1 mark)
1. Biological vector: A biological vector is an organism that can transmit a pathogen from one host to another by acting as a carrier or a host for the pathogen during part of the pathogen's life cycle. The pathogen replicates and develops within the vector, and the vector is essential for the transmission of the pathogen to a new host.
Mechanical vector: A mechanical vector is an organism that can passively transmit a pathogen from one host to another, without the pathogen undergoing any developmental changes or replication within the vector. The pathogen simply attaches onto the vector's body or appendages and is mechanically transported to a new host.
2. Two parasitic diseases transmitted by mosquitoes are:
- Malaria: It is caused by the Plasmodium parasite and is transmitted through the bite of infected Anopheles mosquitoes.
- Dengue fever: It is caused by the Dengue virus and is transmitted through the bite of infected Aedes mosquitoes.
3. Genetic control of mosquitoes as disease vectors involves using techniques such as genetic modification or genetic manipulation to reduce the population of disease-carrying mosquitoes. One such technique is the genetic modification of mosquitoes to produce sterile offspring. This can be done by introducing a gene into the mosquito population that renders the mosquitoes unable to reproduce effectively, resulting in a decline in their population over time.
4. Two examples of mechanical vectors are:
- Houseflies: They can carry and mechanically transmit various pathogens, including bacteria and viruses, on their body or mouthparts.
- Cockroaches: They can also mechanically transmit pathogens, as they crawl through contaminated areas and then come into contact with food or surfaces.
5. Entamoeba histolytica can cause host cell lysis through several mechanisms. One way is by adhering to the surface of the host cell and releasing enzymes that break down the host cell's membrane, leading to cell damage and lysis. Additionally, the parasite can invade the host cell's cytoplasm and feed on its contents, causing further damage and eventual lysis of the host cell.
6. Giardiasis is a parasitic infection caused by the protozoan parasite Giardia lamblia. It affects the small intestine and can cause symptoms such as diarrhea, abdominal cramps, and weight loss.
7. Three types of Leishmaniasis are:
- Cutaneous leishmaniasis: It primarily affects the skin and causes skin sores or ulcers.
- Mucocutaneous leishmaniasis: It affects the mucous membranes in addition to the skin, leading to skin lesions and damage to the mucous membranes of the nose, mouth, and throat.
- Visceral leishmaniasis: It affects internal organs, such as the spleen, liver, and bone marrow, and can be life-threatening if not treated.
8. Blood smear or thin blood films are recommended for the detection of Babesia trophozoites and merozoites. The parasites can be visualized under a microscope by staining the blood smear and examining it for the presence of characteristic Babesia organisms.
9. Babesiosis is a parasitic disease that shares symptoms similar to malaria and is commonly misdiagnosed as malaria. It is caused by the Babesia parasite, which infects red blood cells and can cause symptoms such as fever, fatigue, muscle aches, and hemolytic anemia.
10. Three species of malaria parasites are:
- Plasmodium falciparum: It is responsible for the majority of severe malaria cases and is prevalent in Africa.
- Plasmodium vivax: It is the most widely distributed malaria parasite and can cause relapses due to its ability to form dormant liver stages.
- Plasmodium malariae: It causes a milder form of malaria and has a longer periodicity, with fever recurring every 72 hours.
11. Plasmodium vivax is responsible for malaria relapses. It has the ability to form latent liver stages called hypnozoites, which can remain dormant for extended periods and then reactivate, leading to relapses of the disease.
12. The sexual form of Plasmodium species responsible for malaria transmission is the gametocyte. Gametocytes are produced in the human bloodstream and are taken up by female Anopheles mosquitoes during a blood meal. Inside the mosquito, the gametocytes undergo sexual reproduction, resulting in the formation of new sporozoites, which can then be transmitted to another human host when the mosquito bites.