Malaria

[Hero]

Which of the following is the most favorable condition for malarial infection?
a) Temp <16*C
b) Temp between 20-30*C
c) Temp >33*C
d) Heavy rainfall
e) Altitude >2000 m above sea level
f) All of the above
g) None of the above.
Lots of options, good for you

[Oak]

Ah!!! I would go for "Temp between 20-30*C" and I got the explanations

a) Temp <16*C: Colder temperatures slow down the natural cycles of the parasite, sometimes extending them beyond the longevity of the mosquito, and cease the metabolic activity of the parasite if temperature dips below 16o C, so its out.

b) Temp between 20-30*C : I would go for this.

c) Temp >33*C: I would have chosed this option but the upper limit has not been given as how high ofcourse malaria If the upper limit of this option covers the temperature where human survive then I would say this is the best answer as malaria can occur at 45*C and avove. But if this option mean >33 - infinite say 60, 100 or whaterve value usually more than 50* human find very difficult to survive so I would still go for 20-30 as it has given the lower and upper limt.

d) Heavy rainfall: Rainfall is an important factor in the environmental influence, but it is complex in its effects. Although rainfall increases the amount of water available for the female Anopheles to breed, often large amounts of rain disrupt standing bodies of water, transforming them into moving streams or rivers that will not support larval development. Since it says heavy rainfall its out.

e) Altitude >2000 m above sea level: Malaria is restricted to regions between latitudes 65o N and 40o S and altitudes less than about 2200 meters because of climatic boundaries of the vector. Within the given boundaries, temperature and weather conditions continue to affect the transmission and development abilities of the parasite.

f) All of the above: NO

g) None of the above: Yes, it could be as I have little bit doubt for this option because still I am not happy with the option Temp between 20-30*C as malaria do occur above 30*C.

anyway it gave me a good exercise for my brain... please come with the detail explanation.

[Oak]

Amazing Facts about Malaria:

• 1 million people die of malaria each year.
• 300-500 million cases of malaria occur per year.
• Four Nobel prizes have been awarded for work associated with malaria, to Sir Ronald Ross (1902), Charles Louis Alphonse Laveran (1907), Julius Wagner-Jauregg (1927) and Paul Hermann Muller (1948).
• In Africa, a child dies from malaria every 30 seconds.
• Malaria occurs in over 100 countries and territories. More than 40% of the world’s population is at risk (e.g., parts of Africa, Asia, the Middle East, Central and South America, Hispaniola, and Oceania). .
• The average cost for potentially life-saving treatments of malaria are estimated to be US$0.13 for chloroquine, US$0.14 for sulfadoxine-pyrimethamine, and US$2.68 for a 7-day course of quinine.
• Residents of Asembo Bay (Western Kenya) were bitten 60-300 times a year by a malaria-carrying mosquito in the 1990's, before control measures (including the use of insecticide-treated bed nets) were put in place.
• Among the four malaria species that infect humans, Plasmodium vivax and P. ovale can develop dormant liver stages that can reactivate after symptomless intervals of up to 2 (P. vivax) to 4 years (P. ovale).
• 84% of the blood transfusions given in March-June 2000 in a major hospital in Kinshasa (Democratic Republic of Congo) were for anemia caused by malaria.
• Pregnant women have increased susceptibility to Plasmodium falciparum malaria; in malaria-endemic countries, P. falciparum contributes to 8-14% of low birth weight, which in turn decreases the chance of a baby’s survival
• After a single sporozoite (the parasite form inoculated by the female mosquito) of Plasmodium falciparum invades a liver cell, the parasite grows in 6 days and produces 30,000-40,000 daughter cells (merozoites) which are released into the blood when the liver cell ruptures. In the blood, after a single merozoite invades a red blood cell, the parasite grows in 48 hours and produces 8-24 daughter cells, which are released into the blood when the red blood cell ruptures.

[Hero]

Welcome back Oak. Good answer and thnx for the amazing facts about malaria.
Malaria transmission does not occur at temperatures below 16*C or above 33*C and at altitudes greater than 2000 m above sea level since development in the mosquito (sporogony) cannot take place. The optimum conditions for transmission are high humidity and an ambient temperature between 20*C and 30*C. Although rainfall provides breeding sites for mosquitoes, excessive rainfall may wash away mosquito larvae and pupae.

[Hero]

Someone sent me a PM and suggested not to write rubbish. He/she thinks that temp >33*C is also a favorable condition for malarial infection coz in terai where the temp is usually >33*C and the incidence of malaria is also high. So he /she thinks that answer should be both b and c. Well whoever u r please note-- it is reported in literature that malarial transmission doesn't occur at temp more than 33*C. It would be better if u read this book and then only write to me. -- Manson's Tropical Diseases 21st Ed. Page number 1206 written by Prof Cook GC.

[Alpine]

wow it is a very useful discussion thanks to oak for great explanation and hero for this question.

oak has given the reason malaria do occur in >33 degree C but the upper limit has not been given so obviouly its out hoina ra but it is good that you got a PM it shows that people are interested eventhogh they don't take part in the question answer.