Pathogen: Trypanosoma Brucei Gambiense or Trypanosoma Brucei Rhodesiense
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Each is named for which part of the region the disease was found. Trypanosoma brucei rhodesiense relates to East Africa. Trypanosoma brucei gambiense relates to West Africa.
Category of Pathogen:Protazoa
Name of the disease:African Trypanosomiasis (Sleeping Sickness)
Symptoms:There is three stages of the disease. The first stage is the trypanosomal stage when the fly bites a person. The second stage is the hemolymphatic stage where the parasite is in the blood and travels through the circulatory system. The third stage called the meningoencephalitic stage is when the parasite passes the blood-brain barrier and attacks the Central Nervous System(CNS). This is where the disease becomes lethal.
When bitten by the Tsetse Fly a sore which is called a chancre develops which is the first stage. Infected humans in the second stage develop a fever, swollen lymph nodes, muscle and joint aches, tachycardia, weight loss, and change of their sleep cycle. Usually people start to feel fatigue and sleep more during the day and may have insomnia at night. As the disease progresses into stage three people have personality changes, hallucinations, seizures, and then this leads to death.
Some people do not even start to show symptoms until it is in stage three and then it is too late.
The only ways to test for the parasite is if you give a blood sample to be examined and a spinal tap. The spinal tap is to see if the parasite has reached your CNS.
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http://pathmicro.med.sc.edu/parasitology/sleep8.jpg
Primary Host: Humans because they are where the parasite is mature
Other Hosts: The Tsetse Fly is the secondary host because the parasite grows inside them and the animals too.
The fly bites the infected animal because they are bloodsucking insects. The fly is just a carrier. The parasite is ingested and it multiples in the the gut of the fly and then the fly bites the human and passses it on to them. The parasite is mature when the human becomes the host.
Route of Transmission: It is indirect and it is a vector-borne parasite.
http://www.path.cam.ac.uk/partIB_pract/P14/image04.jpg
R0: N/A
Prevalence: In 2005 there were 50,000-70,000 cases in Africa reported, but there is between 300,000 and 500,000 more cases that are estimated to be undiagnosed.
http://www.stanford.edu/class/humbio103/ParaSites2001/trypanosomiasis/trypanpo_files/image033.jpg
Generation Time: The cycle in the fly takes about 3 weeks for the parasite to mature and then when the human is bit it takes 1-3 weeks for the disease to prevail. If the person is untreated then they usually will die in a few months or within a year at the longest.
Mortality & Morbidity rate: If untreated it is a 100% mortality and morbidity rate.
Also the drugs for treatment are so strong that at least 1 person in 100 people will die from the drugs alone.
Is it preventable? How? No there is no vaccine for it and no preventable drugs. It is preventable by using insect repellant, avoiding bushes, wear neutral clothing because the Tsetse Fly is attracted to bright colors, inspect your vehicle because the fly likes to make it’s home in vehicles, and to wear protective clothing such as long sleeves and pants.
You can treat the disease in the first stage if it has not hit the brain. There are drugs to kill the parasite. The drugs are very powerful. If the disease is caught in the second stage when it has attack the brain, the damage cannot be reversed. When treating the disease it incolves hospitalization of two weeks to a month. Then there is periodic follow-up exams that are required for 2 years.
Does the disease trigger long lasting immunity? No once you recover from the disease you can get re-infected.
When was the pathogen first described and is there evidence that it was around much earlier than that? The first link that the diseased was tied to the Tsetse Fly was in 1901 byÉmile Brumpt. There was evidence of the disease much earlier around the 1300′s.
What is the economic impact of the disease?: This disease has the biggest impact on humans. Many die from the disease because there is no form of healthcare in most parts of where the disease occurs. If they do get diagnoised as having the disease it is often too late because the parasite has hit stage three.
People are starting to test the cattle and stop the parasite before it can be spread to humans.
The coolest part of the disease: It was interesting to read about how the parasite escapes from the immune system. When the immune system starts to notice the parasite, it attacks it. The parasite can mislead the immune system through antigenic variation which the parasite sheds it’s coat.
Citations for the information included:
http://www.youtube.com/watch?v=CAqLCB5K1JA
http://www.dpd.cdc.gov/dpdx/HTML/TrypanosomiasisAfrican.htm
