The PCR-based detection ofTrypanosoma cruziin the faeces ofTriatoma infestansfed on patients with chronic American trypanosomiasis gives higher sensitivity and a quicker result than routine xenodiagnosis

Abstract

In the xenodiagnosis (XD) of American trypanosomiasis (Chagas disease), Trypanosoma cruzi in the triatomine bugs fed on the patient can now be detected using PCR (XD-PCR) as well as by microscopy (XD-M). In a study to compare XD-PCR with XD-M, triatomine bugs were fed on 50 cases of chronic American trypanosomiasis, of whom only 25 were ever found positive by XD-M. Overall, the bugs fed on 34 of the patients (all 25 cases found positive by XD-M and nine of the other patients) were found PCR-positive, giving a 330-bp fragment corresponding to part of the hyper variable region of the kinetoplast DNA of T. cruzi. Of the 25 patients who were ever found positive by XD-M, 20 gave bugs that were smear-positive on day 90 and a similar number (24; P=0.125) gave bugs that were PCR-positive at this time. On day 30, however, the bugs fed on only 11 of these 25 patients were found positive by microscopy, whereas 23 of these patients were found positive by XD-PCR (P=0.0016). Thus, not only was XD-PCR more sensitive than XD-M but it was also quicker, revealing more cases within 30 days than detected using XD-M over a period of 90 days.

Microsatellite marker analysis shows differentiation among Trypanosoma cruzi populations of peripheral blood and dejections of Triatoma infestans fed on the same chronic chagasic patients

“…Microscopic examination of insect dejections was performed 30, 60 and 90 days after feeding triatomines with peripheral blood from infected individuals. The sensitivity of this test is about 80% (Zulantay et al 2007).…”

Evaluation of Nifurtimox Treatment of Chronic Chagas Disease by Means of Several Parasitological Methods

“…T. cruzi contains nuclear DNA and kinetoplast DNA (kDNA), both of which contain many repetitive sequences that are highly suitable for sensitive PCR detection due to their high copy numbers (16,17). Other parasitological methods, such as the classical XD method (18), even though of much less sensitivity than PCR, are still useful in combination with PCR (19,20). Quantitative PCR (qPCR) is the preferable alternative to determine parasitic load after treatment; at the same time, the conventional PCR directed to minicircles is useful to genotype infective T. cruzi lineages (21,22).…”

Detection of Wolbachia Bacteria in Multiple Organs and Feces of the Triatomine Insect Rhodnius pallescens (Hemiptera, Reduviidae)

“…The posterior intestine, rectal ampolla, and salivary glands from wild triatomines were homogenized, and any trypanosomes present were observed with a microscope or cultured in Grace medium to facilitate detection of T. cruzi and T. rangeli (20,21). T. cruzi and T. rangeli were also detected by PCR, as previously described (7,45,46).…”