Parasites and Diseases 2

Parasite and Disease

Malaria

     
Since most of the regions in the world are battling malaria, I thought that would be an interesting topic to tackle. In 2008, the CDC estimated there was 190-311 million cases of malaria worldwide and between 700,000-1,000,000 people died from the disease. Malaria is caused by a parasite carried around by mosquitoes that feed on humans. Also, 3.3 billion people live in areas at-risk for malaria transmission and only 35 countries account for 98% of all malaria-related deaths. 30 of those 35 are in sub-Saharan Africa. As this map shows, the distribution is heavily in sub-Saharan Africa, the Amazon rainforest, and southern/southeast Asia.


The life cycle of the infection is quite simple, it is carried by mosquitoes. First, a female Anopheles mosquito feeds on an affected human and stores the spores in her salivary glands. When the infection is ready, the infected cells burst and infect the mosquito. The salivary gland is then infused with spores which is transmitted to humans. She feeds on an unaffected human and, in turn, injects the malaria spores into the human bloodstream. The spores then travel to the liver and “invade” the liver cells. Over the next few weeks, the spores divide and multiply. When ready, the infection leaves the liver cells into the bloodstream and invade red blood cells, replicate, and multiply. Some of the infected cells leave the replication stage and form into gametocytes, and then gametes. When a mosquito feeds on this human, they will again store the infection in the salivary glands and burst like previously.
The symptoms of malaria are anemia (due to the infection of red blood cells), a fever, convulsions, headache, jaundice (due to liver infection), muscle pain, nausea, bloody stool, sweating, and vomiting. There is a vaccine for malaria but it is administered at hospitals, which is the reason why sub-Saharan Africa is the region most affected by it. They do not have access to any sort of healthcare.

Roundworms (Nematode)

According to the Journal of Experimental Biology, roundworms are one of the most diverse of all animals and are the most numerous multicellular animals on Earth. There have been over 28000 different roundworms documented and two thirds of them are parasitic. I decided to use roundworms because they seem to be the most interesting of all the helminth organisms. As you can see by the map below, most intestinal nematode infestations happen in sub-Saharan Africa and southeast Asia.

There are many symptoms that arise with a roundworm disease, most of them include abdominal pain, diarrhea (sometimes bloody), and fever. The life cycle of all types of roundworms can be broken down into one basic life cycle. The cycle consists of 7 stages, an egg, 4 larval stages, and 2 adult stages comprising both male and female sexes.
The first stage is when the larvae is in the egg. When the egg hatches, the larvae feeds on bacteria and molts, or sheds/grows out of it’s old skin. Roundworms molt 4 times during each life cycle, at the end of each larval stage. Usually around the end of the second larval stage, the roundworm will infect it’s host. At it’s immature adult phase, or the last larval stage, the larvae sexually matures into a male or female. In the adult stage, the helminth will reproduce and start the life cycle all over again.