Term
| Mal-air means bad air. Malaria was also known as ague or marsh fever due to its association with swamps. how many species of malaria are there? how many infect man? |
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Definition
| 175 species but 4 main species affect man |
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Term
| who was alphonse Laveran? |
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Definition
| first person to discover malaria parasites in human blood in 1880 |
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Term
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Definition
| first to demonstrate a mosquito can transmit a malarial parasite in 1897 |
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Term
| who discovered the liver stage of malaria in 1948? |
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Definition
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Term
| how many % of malaria cases are in africa? |
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Definition
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Term
| which gender mosquito transmits malaria and what meal is needed for egg development? |
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Definition
| female Anopheles mosquito transmit malaria. A blood meal is needed for egg development |
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Term
| which geographical areas can anopheles mosquito survive? |
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Definition
| between 60N and 40S and below 2000 metres. temperature is critical in determining Plasmodium development |
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Term
Liver Stage - Sporozoite to Merozoite
explain |
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Definition
| to take blood mosquito injects anticoagulants and vasodilaters into skin. At the same time injects sporozoites beneath the skin. |
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Term
sporozoites infect liver, pass through kupffer cells transiently and find a good hepatic cell. within the parasitophorous vacuole of the hepatic cell sporozoites undergo schizogony.
explain further |
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Definition
| this is mass of cell division without cytokinesis. the newly divided merozoites (30-40,000) are packaged in a merosome and exit kupffer cell. merosome helps merozoites evade capture from kupffer cells. |
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Term
| after innoculation from mosquito bite, how long do sporozoites circulate before penetrating the liver? |
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Definition
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Term
| Sporozoites undergo schizogony. what form of reproduction is this? |
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Definition
| asexual reproduction. nucleus divides many times before cytoplasm divides to 30-40,000 merozoites |
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Term
| in the erythrocytic stage the merozoite turn to a trophozoite but what can the trophozoite turn to? |
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Definition
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Term
| what helps merozoite penetrate host wall? |
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Definition
| rhoptry and microneme discharge. micronemes are cellular organs restricted to the apical third of the protozoan body |
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Term
| describe how merozoites penetrate rbc |
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Definition
| attachment, reorientation and junction formation, discharge of rhoptry and microneme, penetrate past tight junction into rbc forming parasiphorous vacuole, pinching off junction and shedding surface coat, resealing rbc and parasitophorous vacuole |
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Term
| what does a merozoite turn into? |
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Definition
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Term
| trophozoite is a single celled nucleated mass of protoplasm and is highly metabolically active. it needs to acquire nutrients. how does it do this? |
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Definition
| from host cell. it modifies RBC to meet nutritional demands. |
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Term
| trophozoites ingest haemoglobin. this is broken down to give which substance and where does this pigment accumulate? |
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Definition
| broken down to give Haemozoin - this accumulates in the pigment vacuole |
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Term
| after how many hours of growth in the rbc does schizogony occur in which the trophozoite divides to give 8-16 merozoites? |
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Definition
| after approx 40 hours, the RBC ruptures and merozoites are released. |
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Term
| in the erythrocytic stage of malaria the shape of the RBC are altered how? |
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Definition
| irregular appearance of erythrocyte surface and presence of knobs and rhoptries around perimeters of merozoites |
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Term
| after several erythrocytic cycles some trophozoites develop into gametocytes. how long do these gametocytes take to mature? |
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Definition
| approx 4 days but stay viable in blood for prolonged periods. nothing happens to the gametocytes unless they are taken up by a mosquito in a blood meal |
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Term
| how long does it take after ingestion by mosquito for gametocytes to burst out of rbc? |
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Definition
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Term
| how many microgametes does a male gametocyte produce? |
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Definition
| 8 microgametes. they consist of a flagellum with an attached nuclear mass. |
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Term
| what is the female gamete known as? |
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Definition
| macrogamete. the male micro and female macrogamete fuse together forming a zygote. |
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Term
| which is the only stage where plasmodium is diploid? |
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Definition
| insect stage when male micro and female macrogamete fuse togther making a zygote. rest of the stage is haploid thus mosquito is the definitive host. |
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Term
| over the course of 5-10 hours what happens to the zygote? |
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Definition
| it differentiates into a cigar shaped invasive ookinete. this is motile and activley penetrates the intestinal wall of the mosquito. |
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Term
| after penetrating the intestinal wall of the mosquito what happens to the ookinete? |
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Definition
| it differentiates to become an oocyst and attatches to the external side of the midgut wall of the mosquito |
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Term
| oocysts grow rapidly and divide internally to form? |
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Definition
| sporozoites. the oocyst stage is the longest phase in the life cycle (8-35days) and is temperature dependant. |
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Term
| which stage in plasmodium life cycle is the longest? |
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Definition
| the oocyst stage. lasts between 8-35 days. it is temperature dependant so high temp and the sporozoites are made nearer the 8 day marker and if the temperature isnt warm enough it will be more around the 35 day mark. the mosquito has to survive long enough for the oocyst to mature. |
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Term
| what is the most important single factor for malarial transmission? |
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Definition
| survival of the mosquito. |
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Term
| how many sporozoites does each oocyst produce? |
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Definition
| up to 1000. when the oocyst burst the sporozoites are released into the body cavity of the mosquito. |
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Term
| after being released into the mosquitos body cavity where do sporozoites go? |
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Definition
| they migrate to salivary glands and accumulate in salivary ducts. the cycle is completed when the mosquito bites a suseptible host. |
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Term
| what are the 3 distinct stages adapted for invasion by plasmodium? |
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Definition
- Ookinete in mosquito gut epitheleal for gamete fusion and oocyst development
- Sporozoite in liver cells schizogomy into merozoites
- Merozoites in rbc
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Term
| how is malaria diagnosed? (2) |
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Definition
serological testing for malaria specific antibodies
blood smears stained with giemsa to detect and identify malaria species. |
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Term
| which stage of malaria has an incubation period of 2 weeks or longer? |
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Definition
| liver stage. no symptoms associated with this stage |
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Term
| when is fever experienced? |
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Definition
when merozoites burst out of rbc. the toxins induce pyrexia. depending on the malaria fever will follow tertiary or quaternary characteristics. followed by a cold stage followed by a 24 hour fever stage (41-42) followed by a wet stage - profuse sweating.
patients will be exhausted but well until next cycle begins. |
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Term
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Definition
incubation period 2 weeks or longer. liver stage
fever - rbc burst
cold stage - shaking chill
fever - last ~24hours (41-42.c)
wet stage - body temp returns to normal, profuse sweating
patient exhausted but well until next cycle begins |
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Term
| what are the 4 distinct species of plasmodium? |
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Definition
plasmodium falciparum
plasmodium vivax
plasmodium malariae
plasmodium ovale |
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Term
| which species causes sever disease? |
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Definition
| plasmodium falciparum 50% of malaria. it is malignant tertian so you would have a fever every 3rd day. |
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Term
| which 2 plasmodium species have the highest infection rates? |
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Definition
plasmodium falciparum 50% malinant tertian
plasmodium vivax 43% benign tertian |
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Term
| which known plasmodium is the only quartan? |
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Definition
| plasmodium ovale 1% quartan |
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Term
t or f
synchronisation of erythrocytic cycle does not occur in all malarial species? |
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Definition
| true. for example in rodent malaria the erythrocytic stage happens at different times in different red blood cells. |
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Term
| erythrocytic destruction results in which condition? |
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Definition
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Term
| how are organs pigmented? |
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Definition
| phagocytic cells ingest malarial pigment haemozoin so spleen, liver and bone marrow pigmented. |
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Term
| hepatomegaly splenomegaly is a result from? |
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Definition
| dilation of sinuses and increased numbers of macrophages especially in spleen. |
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Term
| how does malaria cause capillary blockages? |
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Definition
| parasitised rbc block capillaries, cause local haemorrhage and anoxia - depletion of oxygen. anoxia affects the brain the most. |
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Term
| intravascular haemolysis in the kidney results in Hb present in blood and urine. what are these conditions called? |
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Definition
Hb present in blood plasma - haemoglobinaemia
Hb present in urin - haemoglobinuria results in very dark urine aka Blackwater fever |
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Term
| why is malaria also known as blackwater fever? |
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Definition
| haemoglobinuria - presence of Hb in urine due to intravascular haemolysis in the kidney |
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Term
| why is plasmodium falciparum more pathogenic? |
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Definition
| Sequestration - infected rbc cytoadhere to endothelial cells that line post capillary venules in tissues like the brain, liver, kidney and muscles. parasite proteins (PfEMP1) are transported to surface of iRBC. concentrated in knob structures. these parasite proteins bind host receptors thus iRBC sticks to host cells and is removed from peripheral circulation. |
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