25.4 Parasitic infections of the circulatory and lymphatic systems  (Page 4/13)

Babesiosis

Babesiosis is a rare zoonotic infectious disease caused by Babesia spp . These parasitic protozoans infect various wild and domestic animals and can be transmitted to humans by black-legged Ixodes ticks. In humans, Babesia infect red blood cells and replicate inside the cell until it ruptures. The Babesia released from the ruptured red blood cell continue the growth cycle by invading other red blood cells. Patients may be asymptomatic, but those who do have symptoms often initially experience malaise, fatigue, chills, fever, headache, myalgia, and arthralgia. In rare cases, particularly in asplenic (absence of the spleen) patients, the elderly, and patients with AIDS , babesiosis may resemble falciparum malaria, with high fever, hemolytic anemia, hemoglobinuria (hemoglobin or blood in urine), jaundice, and renal failure, and the infection can be fatal. Previously acquired asymptomatic Babesia infection may become symptomatic if a splenectomy is performed.

Diagnosis is based mainly on the microscopic observation of parasites in blood smears ( [link] ). Serologic and antibody detection by IFA can also be performed and PCR-based tests are available. Many people do not require clinical intervention for Babesia infections, however, serious infections can be cleared with a combination of atovaquone and azithromycin or a combination of clindamycin and quinine .

Chagas disease

Also called American trypanosomiasis , Chagas disease is a zoonosis classified as a neglected tropical disease (NTD). It is caused by the flagellated protozoan Trypanosoma cruzi and is most commonly transmitted to animals and people through the feces of triatomine bugs. The triatomine bug is nicknamed the kissing bug because it frequently bites humans on the face or around the eyes; the insect often defecates near the bite and the infected fecal matter may be rubbed into the bite wound by the bitten individual ( [link] ). The bite itself is painless and, initially, many people show no signs of the disease. Alternative modes of transmission include contaminated blood transfusions, organ transplants from infected donors, and congenital transmission from mother to fetus.