Home Economics American Trypanosomiasis Chagas Disease, Second Edition: One Hundred Years of Research
Application of diagnostic tests in different contexts
As explained in the beginning of this chapter, Chagas disease has two main phases, acute and chronic, and diagnostic tests should be applied according to the suspected phase. During acute phase, parasitological tests are preferred and serological tests are used only if the former were negative and suspicion persists. For the chronic phase, serological tests are the option, and parasitological only used in special circumstances. Even if major groups of tests are parasitological and serological, other tests which are not routinely used have been employed. Search for antigen during the acute and chronic phase has been the subject of a few investigations. Skin tests have been tried without success140,141 and, as an invasive procedure, may have ethical consequences, mainly when there are other tests that are easier to perform.
Furthermore, there is the context of the clinical situation to consider. For example, there is the confirmation of a suspected case against exclusion of a donor. A responsible diagnostic laboratory should concentrate all efforts to demonstrate or exclude the presence of the infection. The hematologists need to be sure that the blood is not infected. If there is any suspicion, even if not confirmed after, blood should be discarded. There are other situations in which a special array of tests or timing is necessary, such as epidemiological surveys and congenital transmission. Each one of these situations needs to be analyzed. For a better handling some examples are given below, including in each the clinical context, epidemiology, laboratory tests to be requested, and action to be done.
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