The infection of millions of people with the protozoan parasite Trypanosoma cruzi is a public health concern. Treatments for Chagas' disease remain marginally effective. Cardiac and gastrointestinal complications dominate the clinical picture.

Quiz Ref ID Chagas disease is caused by Trypanosoma cruzi, a protozoan parasite usually transmitted by infected triatomine bugs. Transmission also occurs through transfusion or organ transplantation, from mother to infant, and rarely by ingestion of contaminated food or drink.^1-3 Vector-borne transmission occurs exclusively in the Americas, where an estimated 8 million to 10 million people have Chagas disease.^4,5 Historically, transmission has occurred predominantly in rural areas of Latin America, where poor housing conditions have promoted contact with infected vectors. Successful programs to reduce vector- and blood-borne transmission, as well as migration within and beyond endemic countries, have changed the epidemiology of the disease.^4,6,7

SUMMARY: Chagas' disease is caused by the protozoan parasiteTrypanosoma cruziand causes potentially life-threatening disease of the heart and gastrointestinal tract. The southern half of the United States contains enzootic cycles ofT. cruzi, involving 11 recognized triatomine vector species. The greatest vector diversity and density occur in the western United States, where woodrats are the most common reservoir; other rodents, raccoons, skunks, and coyotes are also infected withT. cruzi.In the eastern United States, the prevalence ofT. cruziis highest in raccoons, opossums, armadillos, and skunks. A total of 7 autochthonous vector-borne human infections have been reported in Texas, California, Tennessee, and Louisiana; many others are thought to go unrecognized. Nevertheless, mostT. cruzi-infected individuals in the United States are immigrants from areas of endemicity in Latin America. Seven transfusion-associated and 6 organ donor-derivedT. cruziinfections have been documented in the United States and Canada. As improved control of vector- and blood-borneT. cruzitransmission decreases the burden in countries where the disease is historically endemic and imported Chagas' disease is increasingly recognized outside Latin America, the United States can play an important role in addressing the altered epidemiology of Chagas' disease in the 21st century.

To address the source of infection in humans and public health importance of Giardia duodenalis parasites from animals, nucleotide sequences of the triosephosphate isomerase (TPI) gene were generated for 37 human isolates, 15 dog isolates, 8 muskrat isolates, 7 isolates each from cattle and beavers, and 1 isolate each from a rat and a rabbit. Distinct genotypes were found in humans, cattle, beavers, dogs, muskrats, and rats. TPI and small subunit ribosomal RNA (SSU rRNA) gene sequences of G. microti from muskrats were also generated and analyzed. Phylogenetic analysis on the TPI sequences confirmed the formation of distinct groups. Nevertheless, a major group (assemblage B) contained most of the human and muskrat isolates, all beaver isolates, and the rabbit isolate. These data confirm that G. duodenalis from certain animals can potentially infect humans and should be useful in the detection, differentiation, and taxonomy of Giardia spp.

Chagas disease causes the highest burden of any parasitic disease in the Western hemisphere. By applying published seroprevalence figures to immigran