From pages 88-90, Dr. Moalem relates to big idea 4 (biological systems interact, and these systems and their interactions possess complex properties) when he begins discussing Malaria. Malaria is a potential life-threatening disease, especially in children and pregnant women. Malaria is caused by parasitic protozoa, Plasmodium, that lives as a parasite in humans and Anopheles mosquitos. Towards the bottom of page 88, Dr. Moalem states that there are a few different species that cause malaria, but the most dangerous is Plasmodium falciparum.
Where is malaria most prevalent? Why do you think this is? Why are children and pregnant women more vulnerable to malaria (consider how our bodies combat parasites)? Research and list the different species of the malaria parasite. Why do you think Plasmodium falciparum has evolved to be more virulent than the others? Refer back to Unit 1 on evolution and natural selection, as well as page 119 to help answer this question.
(Sarah Terwilliger, sterwil3@students.d125.org)
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ReplyDeleteMalaria is most prevalent in Africa. According to the CDC (Centers for Disease Control and Prevention), "Malaria is transmitted in tropical and subtropical areas where Anopheles mosquitoes can survive and multiply" and where "Malaria parasites can complete their growth cycle in the mosquitoes". Also, according to The Guardian's data blog, "the heartland of Malaria" is in sub-Saharan Africa. Children and pregnant women are more vulnerable to malaria because they are at the stage in life where they have weaker immune systems. Pregnancy reduces the woman's immunity to malaria. Also, children aren't exposed to the different pathogens, and thus their bodies aren't able to fight off foreign substance as quickly. Overall, their bodies cannot combat parasites that cause malaria as well.
ReplyDeleteCrystal Chang (cchang3@students.d125.org)
Some examples of malaria parasites are P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi. The reason that P. falciparum causes severe malaria is because it is able to multiply rapidly in the blood, which can cause severe blood loss, or anemia. Also, the infected parasites can clog up small blood vessels. If this occurs in the brain, it can cause severe and fatal cerebral malaria. This malaria parasite is found in tropical and subtropical areas, where malaria is prevalent. P. vivax is another type of malaria parasite found in Asian areas. This is mainly spread throughout humans due to the densely populated areas. This one is unique in that it has dormant liver stages, where it doesn't invade the blood until several months or years after the mosquito bite.P. malariae is the only malaria parasite that has a quartan cycle (three-day cycle). Also, when untreated, this can cause a lifetime infection.
ReplyDeleteCrystal Chang (cchang3@students.d125.org)
On page 119 of Survival of the Sickest, Moalem states that the evolutionary advantage for the malaria parasite is "for the malaria parasite to push its host toward the brink of death". Also, these parasites no longer need the help of the human body to "meet new hosts". Instead, by concentrating the human bloodstream with parasites, it ensures that the mosquito that sucks our blood will ingest the parasite. Thus, the parasite would be finding a new host. There seems to be constant cycle with the malaria parasite. It is in the mosquito, the mosquito bites the human, the parasite is in the human, the human's blood is packed with parasites, and then the mosquito would suck the parasite along with the blood from the human.
ReplyDeleteAlso, the theory of evolution fits right into the evolution and growth of malaria parasites. As the body is more able to fight off malaria and as malaria replicates/grows in its host, mutations are more likely to occur. Small changes in the parasite makes it harder for the body to fight it off.
Crystal Chang (cchang3@students.d125.org)