Trypanosoma cruzi loop-mediated isothermal amplification (Trypanosoma cruzi Loopamp) kit for detection of congenital, acute and Chagas disease reactivation.

A Trypanosoma cruzi Loopamp kit was recently developed as a ready-to-use diagnostic method requiring minimal laboratory facilities. We evaluated its diagnostic accuracy for detection of acute Chagas disease (CD) in different epidemiological and clinical scenarios. In this retrospective study, a convenience series of clinical samples (venous blood treated with EDTA or different stabilizer agents, heel-prick blood in filter paper or cerebrospinal fluid samples (CSF)) from 30 infants born to seropositive mothers (13 with congenital CD and 17 noninfected), four recipients of organs from CD donors, six orally-infected cases after consumption of contaminated guava juice and six CD patients coinfected with HIV at risk of CD reactivation (N = 46 patients, 46 blood samples and 1 CSF sample) were tested by T. cruzi Loopamp kit (Tc LAMP) and standardized quantitative real-time PCR (qPCR). T. cruzi Loopamp accuracy was estimated using the case definition in the different groups as a reference. Cohen's kappa coefficient (κ) was applied to measure the agreement between Tc LAMP (index test) and qPCR (reference test). Sensitivity and specificity of T. cruzi Loopamp kit in blood samples from the pooled clinical groups was 93% (95% CI: 77-99) and 100% (95% CI: 80-100) respectively. The agreement between Tc LAMP and qPCR was almost perfect (κ = 0.92, 95% CI: 0.62-1.00). The T. cruzi Loopamp kit was sensitive and specific for detection of T. cruzi infection. It was carried out from DNA extracted from peripheral blood samples (via frozen EDTA blood, guanidine hydrochloride-EDTA blood, DNAgard blood and dried blood spots), as well as in CSF specimens infected with TcI or TcII/V/VI parasite populations. The T. cruzi Loopamp kit appears potentially useful for rapid detection of T. cruzi infection in congenital, acute and CD reactivation due to HIV infection.

Multiplex Real-Time PCR Assay Using TaqMan Probes for the Identification of Trypanosoma cruzi DTUs in Biological and Clinical Samples.

BACKGROUND: Trypanosoma cruzi has been classified into six Discrete Typing Units (DTUs), designated as TcI-TcVI. In order to effectively use this standardized nomenclature, a reproducible genotyping strategy is imperative. Several typing schemes have been developed with variable levels of complexity, selectivity and analytical sensitivity. Most of them can be only applied to cultured stocks. In this context, we aimed to develop a multiplex Real-Time PCR method to identify the six T. cruzi DTUs using TaqMan probes (MTq-PCR). METHODS/PRINCIPAL FINDINGS: The MTq-PCR has been evaluated in 39 cultured stocks and 307 biological samples from vectors, reservoirs and patients from different geographical regions and transmission cycles in comparison with a multi-locus conventional PCR algorithm. The MTq-PCR was inclusive for laboratory stocks and natural isolates and sensitive for direct typing of different biological samples from vectors, reservoirs and patients with acute, congenital infection or Chagas reactivation. The first round SL-IR MTq-PCR detected 1 fg DNA/reaction tube of TcI, TcII and TcIII and 1 pg DNA/reaction tube of TcIV, TcV and TcVI reference strains. The MTq-PCR was able to characterize DTUs in 83% of triatomine and 96% of reservoir samples that had been typed by conventional PCR methods. Regarding clinical samples, 100% of those derived from acute infected patients, 62.5% from congenitally infected children and 50% from patients with clinical reactivation could be genotyped. Sensitivity for direct typing of blood samples from chronic Chagas disease patients (32.8% from asymptomatic and 22.2% from symptomatic patients) and mixed infections was lower than that of the conventional PCR algorithm. CONCLUSIONS/SIGNIFICANCE: Typing is resolved after a single or a second round of Real-Time PCR, depending on the DTU. This format reduces carryover contamination and is amenable to quantification, automation and kit production.

Human papilloma virus risk factors for infection and genotype distribution in aboriginal women from Northern Argentina.

The mortality rate for cervical cancer (CC) in Northern Argentina is three times higher than the average for the country (7.8 deaths/100,000 women). We determined the prevalence and genotype distribution of human papillomavirus (HPV) in 227 sexually active women of the native Pilagá community in Formosa, Argentina. We also conducted an HPV-16 variant analysis and studied several community factors that might play a role in viral entry and infection. Endo and exocervical samples were tested for HPV DNA with MY09/11-PCR or with GP5+/6+-PCR. HPV was detected in 46.7% of the samples and 21 different types were found; the most frequent being HPV-16 (19.4%), -6 and -18 (5.3%), -58 (3.5%) and -31 and -33 (3.1%). In relation to HPV-16 variants, 68.2% were European and 31.8% Asian-American. Among the cofactors analyzed only disposal of hu man excreta to the open air (P=0.01) was significantly associated with HPV infection. Our prevalence estimates clearly show that Pilagá women are highly exposed to or infected with high risk HPV types and therefore are at a high risk of developing precancerous lesions and eventually CC at the population level.

Human papillomavirus risk factors for infection and genotype distribution in aboriginal women from Northern Argentina / Virus papiloma humano (hpv) en mujeres de la etnia Pilagá del nordeste argentino: Factores de riesgo de infección y distribución de tipos virales

The mortality rate for cervical cancer (CC) in Northern Argentina is three times higher than the average for the country (7.8 deaths/100 000 women). We determined the prevalence and genotype distribution of human papillomavirus (HPV) in 227 sexually active women of the native Pilagá community in Formosa, Argentina. We also conducted an HPV-16 variant analysis and studied several community factors that might play a role in viral entry and infection. Endo- and exocervical samples were tested for HPV DNA with MY09/11-PCR or with GP5+/6+-PCR. HPV was detected in 46.7% of the samples and 21 different types were found; the most frequent being HPV-16 (19.4%), -6 and -18 (5.3%), -58 (3.5%) and -31 and -33 (3.1%). In relation to HPV-16 variants, 68.2% were European and 31.8% Asian-American. Among the cofactors analyzed only disposal of human excreta to the open air (P=0.01) was significantly associated with HPV infection. Our prevalence estimates clearly show that Pilagá women are highly exposed to or infected with high risk HPV types and therefore are at a high risk of developing precancerous lesions and eventually CC at the population level.

La tasa de mortalidad por cáncer cervical (CC) en la región norte de la Argentina es tres veces más alta que la media del país (7.8 muertes/100 000 mujeres). En el presente trabajo se determinó la prevalencia de infección por virus papiloma humano (VPH) y la distribución y frecuencia de los genotipos en 227 mujeres sexualmente activas de la etnia aborigen Pilagá (Formosa, Argentina). También se realizó un análisis de las variantes intratípicas de VPH-16 presentes en la comunidad y se analizaron diversos factores socioculturales que podrían tener algún rol destacado en la transmisión de la infección viral. Se estudiaron muestras de células endo-exocervicales mediante PCR basadas en los cebadores MY09/11 y GP5+/6+ con posterior restricción enzimática y/o hibridación dot-blot. La infección por VPH fue detectada en el 46.7% de las mujeres analizadas. Fueron identificados 21 genotipos, de los cuales los más frecuentes fueron HPV-16 (19.4%), -6 y -18 (5.3%), -58 (3.5%) y -31 y -33 (3.1%). Respecto al HPV-16, se encontraron 68.2% de variantes europeas y 31.8% de asiático-americanas. Entre los cofactores analizados, solo la disposición de excretas al aire libre estuvo significativamente asociada con la infección por VPH (P = 0.01). Los datos obtenidos reflejan que la comunidad Pilagá está altamente expuesta a las infecciones por genotipos de alto riesgo de VPH, lo cual puede estar asociado a una alta incidencia de lesiones cervicales preneoplásicas y neoplásicas.