Chagas Disease
It is estimated that as many as 8 to 11 million people in Mexico, Central
America, and South America have Chagas disease. Most people are asymptomatic and
do not know they are infected. However, approximately 20 to 30 percent of those
with chronic infection will develop clinically apparent disease, making it a
significant public health concern.
Chagas disease is caused by infection with Trypanosoma cruzi, a protozoan
parasite. In Chagas endemic countries, it is typically transmitted by infected
triatomine bugs (commonly known as kissing bugs). The insects defecate during or
after feeding and the feces enter the human body through the bite wound or
mucous membranes. Alternatively, transmission can occur congenitally (from
mother to infant), through blood transfusion or organ transplantation,
accidental laboratory exposure, or rarely through ingestion of food contaminated
by infected bugs. Transmission in the United States is rare and does not follow
the same pattern as endemic countries. Congenital and transfusion transmission
are more common, mostly attributed to better housing conditions. Additionally,
the triatomine species present in the United States (Triatoma sanguisuga) prefer
animal hosts and do not defecate immediately after feeding.
 
Although local transmission in Florida has not yet been documented, it is
possible due to the demonstrated presence of both infected triatomine bugs and
infected reservoirs such as raccoons. There have been cases of autochthonous
transmission in Texas, Tennessee, California, and Louisiana. People in less
affluent areas of Florida likely have a greater chance of becoming infected.
Once transmission has taken place, most infected individuals experience an acute
illness phase with mild symptoms or nonspecific febrile illness that frequently
goes unrecognized. After four to eight weeks or more, individuals enter the
chronic phase and parasites are generally not detected in the blood. Without
treatment, they will remain infected for life. As previously mentioned, some
people will remain asymptomatic (indeterminate infection) but others (20-30%)
will experience clinical symptoms including cardiac damage. This can range from
mild changes on electrocardiogram to severe arrhythmias, cardiomyopathy, and
sudden death. The digestive tract can also be involved leading to megaesophagus
or megacolon. Finally, the peripheral and central nervous systems can be
affected.
Since the introduction of blood donation screening for Chagas in 2007, more
chronic infections in the United States are being recognized. The blood centers
perform an enzyme-linked immunosorbent assay (ELISA). Donations that have repeat
reactive ELISAS should be confirmed with a radioimmuno-precipitation assay (RIPA).
In a 2005 study by the American Red Cross to evaluate the Chagas screening assay
used by blood donation centers, 51% of donors with repeat reactive screening
tests had positive results on RIPA. Blood banks should notify individuals with
positive results and ideally both provide contact information for the county
health department to the donor and notify the CHD of the result. CHDs are
encouraged to develop relationships with blood centers to facilitate this flow
of information.
Infected individuals should be referred to a local physician or clinic for
follow-up care and treatment. In the United States, antitrypanosomal medication
(nifurtimox or benznidazole) is only available through CDC under an
investigational drug protocol. The physician should call CDC to determine
whether treatment is indicated. The CDC consult line for physicians is (770)
488-7775. Medications are free of charge for eligible patients and will be
shipped directly to the physicians office.
Additional information on Chagas disease can be found on
the Centers for Disease Control and Prevention (CDC) website at
http://www.cdc.gov/parasites/chagas/
Information for County Health Departments
Chagas Disease Guidelines
(53 KB PDF)
Florida Chagas Disease Case Report Form
(24 KB PDF)
CDC Specimen Submission Form (60 KB PDF)
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