Sleeping sickness and Yellow fever

Sleeping sickness:

Also known as Trypanosomiasis. It is a systemic disease caused by the parasite Trypanosoma brucei. East African trypanosomiasis is caused by T. b. rhodesiense, and West African trypanosomiasis by T. b. gambiense. A gray-brown insect called tsetse fly transmits the disease.

Trypanosomes are parasites with a 2-host life cycle: mammalian and arthropod. The life cycle starts when the trypanosomes are ingested during a blood meal by the tsetse fly from a human reservoir in the West African trypanosomiasis or an animal reservoir in the East African form. The trypanosome multiplies over a period of 2-3 weeks in the fly midgut; then, the trypanosomes migrate to the salivary gland where they develop into epimastigotes. The metacyclic trypomastigotes infect humans.

African trypanosomiasis is confined to tropical Africa between 15° north latitude and 20° south latitude, or from north of South Africa to south of Algeria, Libya, and Egypt. The disease is common in the bushes and game parks, not in the urban areas.

Symptoms: The symptoms are initially nonspecific (fever, skin lesions, rash, edema, or lymphadenopathy); however, the infection progresses to meningoencephalitis. Symptoms generally appear within 1 to 3 weeks of infection. East African trypanosomiasis is more acute clinically, with earlier central nervous system involvement than in the West African form of the disease. Untreated cases can be fatal.

Treatment: The infection can usually be cured by an appropriate course of anti-trypanosomal therapy. Pentamidine isethionate and suramin are the drugs of choice to treat the hemolymphatic stage of West and East African trypanosomiasis, respectively. Melarsoprol is the drug of choice for late disease with central nervous system involvement (infections by T.b. gambiense or T.b. rhodesiense. It is always recommended to consult the tropical disease specialist. There is no vaccine discovered yet.

Yellow Fever:

Thankfully this disease has vaccine and vaccination is mandatory for someone traveling to regions endemic to yellow fever. Yellow fever is a tropical disease that is spread to humans by infected mosquitoes. It is caused by the yellow fever virus. There are two types of yellow fever, spread by two different cycles of infection.

Jungle yellow fever is mainly a disease of monkeys. It is spread from infected mosquitoes to monkeys in the tropical rain forest. People get jungle yellow fever when they put themselves in the middle of this natural cycle and are bitten by mosquitoes that have been infected by monkeys. Jungle yellow fever is quite rare and occurs mainly in persons who work in tropical rain forests.

Urban yellow fever is a disease of humans. It is spread by mosquitoes. Females of Aedes aegypti is the type of mosquito that usually carries yellow fever from human to human. These mosquitoes have adapted to living among humans in cities, towns, and villages. Urban yellow fever is the cause of most yellow fever outbreaks and epidemics.

Symptom: Symptoms start 3 to 6 days after being bitten by an infected mosquito. Many yellow fever infections are mild, but the disease can cause severe, life-threatening illness. Symptoms of severe infection are high fever, chills, headache, muscle aches, vomiting, and backache. After a brief recovery period, the infection can lead to shock, bleeding, and kidney and liver failure. Liver failure causes jaundice (yellowing of the skin and the whites of the eyes), which gives yellow fever its name. Yellow fever is diagnosed by a blood test, like malaria.