Chagas Disease

What is trypanosoma cruzi?

protozoan, elongated, spindle-shaped cells with a single nucleus lying near the middle of its length and a single posterior located flagellum (hemoflagelid)

What is another term for chagas disease?

american trypanosomiasis

What is the etiologic agent of american trypanosomiasis (chagas disease) in dogs and humans?

trypanosoma cruzi

Where does trypanosoma cruzi settle?

travels through the bloodstream and settles in the heart muscle (myocardium)

What transmits trypanosoma cruzi?

triatomine bugs (triatoma, rhodnius, panstrongylus)

What is the common transmission route of trypanosoma cruzi in North America?

oral ingestion of infected arthropod

What is the common transmission route of trypanosoma cruzi in South America?

stercorarian; contamination of the host’s mucous membranes or abraded skin by the arthropod’s feces

What is the acute phase of trypanosoma cruzi infection?

no clinical signs are observed but if noted, enlargement of the lymph nodes and spleen (immune system trying to fight off infection), pale gums (poor circulation), decreased appetite, and diarrhea, some may experience sudden death

What is the intermediate phase of trypanosoma cruzi infection?

typically lasts 1-4 months and is usually asymptomatic, some experience sudden death but most enter the chronic phase

What is the chronic phase of trypanosoma cruzi infection?

most cases of chagas are diagnosed at this phase, as parasites continue to replicate dogs develop signs of heart failure, arrhythmias, coughing, exercise intolerance, shortness of breath, fever, lethargy, enlarged liver/spleen, pale gums, enlarged lymph nodes, distended abdomen, sudden death

In other terms, what is the clinical presentation summary of acute infection?

collapse, arrhythmias, lymphadenopathy/splenomegaly, fever, neurological signs

In other terms, what is the clinical presentation summary of chronic infection?

arrhythmias, ascites, congestive heart failure, weight loss, lethargy, acute death

What are the microscopic findings of trypanosoma cruzi?

identification of trypomastigotes on a buffy coat or whole blood, trypomastigotes and amastigotes in needle aspirates of enlarged lymph nodes or histopathologic section of the heart

What are the serology testings available for trypanosoma cruzi?

indirect fluorescent antibody testing

What are the PCR findings of trypanosoma cruzi?

used to detect parasite DNA in blood and tissue, antemortem testing of blood samples can detect circulating trypomastigotes; test results are limited by number of circulating organisms present

What are the characteristics of Dirofilaria immitis?

filarial nematode with a mosquito vector; pulmonary arteries and right heart as primary lesion site and rare zoonotic infection

What are the characteristics of trypanosoma cruzi?

hemoflagellate protozoan with a triatomine (kissing bug) vector; myocardium as primary lesion site and major zoonotic infection potential

What is the common term for dracunculus insignis?

canine guinea worm

What is dracunculus insignis?

rare blister-like cutaneous swelling, nonhealing ulcer on dog’s distal limb or ventral abdomen, female worm may protrude from ulcerative lesion; may confused with aberrant adult D. immitis

What is the treatment for a dracunculus insignis infection?

careful surgical extraction with blunt dissection

What is the first step of a trypanosoma cruzi infection?

triatomine bug takes a blood meal and pass metacyclic trypomastigotes in feces

What is the second step of a trypanosoma cruzi infection?

metacyclic trypomastigotes penetrate various cells at bite wound site and inside those cells they transform into amastigotes

What is the third step of a trypanosoma cruzi infection?

amastigotes multiply by binary fission in cells of infected tissues

What is the fourth step of a trypanosoma cruzi infection?

intracellular amastigotes transform into trypomastigotes, then burst out of the cell and enter bloodstream

What is the fifth step of a trypanosoma cruzi infection?

triatomine bug takes blood meal and ingests trypomastigotes