Page 212 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 181

Figure 3.37 Climatic zones. The climate and topography of a country will determine the range of arthro-
pod vectors present and therefore allows some prediction of the likely presence or absence of specific
vector-borne diseases: (A) cool humid zones (continental summer and subarctic); (B) dry zones (desert and
steppe); (C) warm humid zones (Mediterranean, humid subtropical and west coast regions); (D) tropical
humid zones (rain forest and savannah). There are a wide range of variations within zones depending on
the factors such as altitude and vegetation. The map illustrates climatic zones and zoogeographical regions.

therefore allow an assessment of which proto- the disease also affects people in the USA.
zoal diseases and other arthropod transmitted The symptoms of Chagas disease vary over the
diseases are likely to occur in a given region. course of an infection. In the early, acute stage,
The role of wildlife reservoirs in livestock dis- symptoms are often mild and usually produce
ease outbreaks is discussed further in Chapter 9. no more than local swelling at the site of infec-
tion. After 4–8 weeks, individuals with active
infections enter the chronic phase of Chagas
Trypanosomiasis in humans and disease that is asymptomatic for 60–80% of
community engagement
chronically infected individuals through their
Trypanosomiasis causes significant human lifetime. There are various treatment options.
morbidity and mortality in many parts of the Antiparasitic treatments given in the acute phase
developing world. Chagas disease is caused by of the infection may delay or prevent the devel-
Trypanosoma cruzi, a parasite spread by blood- opment of disease symptoms during the chronic
sucking reduviid bugs (for example, Rhodnius phase of the disease, but 20–40% of chronically
prolixus), and is one of the major health prob- infected individuals may still go on to develop
lems in South America. Due to immigration, life-threatening heart and digestive system

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