Parasitic infections Flashcards
1
Q
Two types of parastic organisms that cause disease?
A
- Protozoa: UNICELLULAR EUKARYOTIC
- Helminths: MULTICELLULAR EUKARYOTIC - parasitic worms
- Protozoa and helminths are usually endoparasites = live inside the body
2
Q
Different routes of parasitic infection transmission
A
- Contaminated food
- Contaminated water
- Walking bare feet
- Bug bites
- Sexual contact
- Close contact with infected pets
- Lack of hygiene
3
Q
Lifecycle of the malaria parasite
A
- Caused by P. falciparum (75%) and P. vivax (20%) = parasitic protozoans
1. Female Anopheles mosquito transmits sporozoite to human host
2. Sporozoites infect liver cells/hepatocytes and mature into schizonts, which rupture and release merozoites
3. After initial replication in liver, the parasites undergo asexual multiplication in the erythrocytes
4. Merozoites infect RBCs and initiate a series of asexual multiplication cycles that produce 8 to 24 new infective merozoites
5. Now, the cells burst and the new infective cycle begins
6. Other merozoites develop into immature gametocytes
7. Gametocytes are ingested by an Anopheles mosquito during a blood meal
8. The parasites multiplication in the mosquito is known as the sporogonic cycle
9. While in the mosquitos stomach, the gametocytes fuse generating zygotes, the zygotes become motile and elongates which invade the midgut wall of the mosquito where they develop into oocysts
10. The oocysts grow, rupture, and release sporozoites which make their way to the mosquito’s salivary glands
11. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle!
4
Q
Symptoms of malaria
A
- Begin 8-25 days following an infection
- Initial manifestations are flu-like
Headache
Fever
Shivering
Joint pain
Vomiting
Haemolytic anaemia
Jaundice
5
Q
Treatment of malaria
A
- Antimalarials (treatment or prevention)
- Quinolones: block parasite detoxification of heme
- E.g. quinine, chloroquinine, amodiaquine, mefloquine, primaquine - Anti-folates - folic acid metabolism
- Sulfonamides, pyrimethamine, proguanil, chlorproguanil - Artesmisin (new) - Generation of free radicals that alkylate and oxidise proteins and lipids within infected RBCs
- Artesunate, artemether, dihydroartemisinin
6
Q
African trypanosomiasis:
- Causative species
- Transmission route
- Signs and symptoms
- Treatment
A
- Causative species
- TRYPANOSOMA BRUCEI
- Parasitic disease - Transmission route
- Bite of an infected tsetse fly - Signs and symptoms
- Stage 1 (1-3 weeks after bite)
Fevers
Headaches
Itchiness
Joint pain
Parasite found in peripheral circulation
- Stage 2 (weeks to months after bite)
Parasite crosses blood-brain barrier and infects CNS
Confusion
Poor concentration
Numbness
Trouble sleeping
Untreated infection eventually leads to coma and death
- Treatment
- Pentamidine
- Suramin
- Melarosoprol
- Eflornithine
- Nifurtimox
7
Q
How is Leishmaniasis transmitted?
A
Bite of certain type of sandflies
8
Q
How is toxoplasmosis transmitted?
A
- Toxoplasma gondii
- Eating poorly cooked food
- Exposure to cat faeces
- Mother to child
9
Q
Soil-transmitted helminthiases symptoms
- Commonly used drugs?
A
- Usually no symptoms
- Heavy infections: Abdo pain Diarrhoea Blood and protein loss Rectal prolapse Physical and cognitive growth retardation
- Drugs
Albendazole
Mebendazole
10
Q
Life cycle of Ascariasis (round worm)
A
- Adult worms live in the lumen of the small intestine
- Eggs in faeces
- Embryonate/fertilised eggs mature to infective form
- Swallowed by human
- Larvae hatch
- Invasion of intestinal mucosa
- Portal circulation
- Systemic circulation to lungs
- Larvae maturation in the lungs
- Penetration of alveolar walls
- Ascend bronchial tree to throat
- Swallowed
- Go to small intestine where they develop into adult forms
11
Q
Transmission of onchocerciasis (RIVER BLINDNESS)
A
Bites of infectied simulium blackflies, which breed in fast-flowing streams and rivers
- Onchocerciasis is a major cause of blindness in many African countries
