Parasite persistence in treated chagasic patients revealed by xenodiagnosis and polymerase chain reaction

• Main Authors: Constança Britto, Celeste Silveira, Maria Angelica Cardoso, Patricia Marques, Alejandro Luquetti, Vanize Macêdo, Octavio Fernandes
• Format: Article
• Language: English
• Published: Instituto Oswaldo Cruz, Ministério da Saúde 2001-08-01
• Series: Memórias do Instituto Oswaldo Cruz.
• Subjects: Trypanosoma cruzi; kinetoplast DNA; Chagas disease; PCR; treatment
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0074-02762001000600014

Polymerase chain reaction (PCR) was compared with xenodiagnosis performed 20 years after trypanocidal chemotherapy to investigate parasite clearance. Eighty-five seropositive individuals for Chagas disease presenting a positive xenodiagnosis were treated with specific drugs; 37 in the acute phase and 48 in the chronic phase. Fifteen chronic assymptomatic patients received a placebo. Treatment in the acute phase led to PCR negative results in 73% of the cases, while xenodiagnosis was negative in 86%. In the chronic phase, PCR was negative in 65% of the patients and 83% led to xenodiagnosis negative results. Regarding the untreated group (placebo), 73% gave negative results by xenodiagnosis, of which 36% were positive by PCR. Individuals that were considered seronegative (n=10), presented unequivocally negative results in the PCR demonstrating the elimination of parasite DNA. Seventeen individuals had their antibodies titers decreased to such a level that the final results were considered as doubtful and 16 of them presented negative PCR. The molecular method represents a clear advantage over conventional techniques to demonstrate persistent infections in Chagas disease patients that underwent chemotherapy.