Assessing reservoir host status in leishmaniasis with special reference to the infectiousness of Leishmania (Viannia) braziliensis infections in wild rodents

ABSTRACT Molecular methods have been responsible for a notable increase in the detection of Leishmaniinae infections in wild animals. Determining their infectiousness is of paramount importance in evaluating their epidemiological significance. One of the most efficient ways of determining infectiousness for vector borne diseases is xenodiagnosis with the appropriate vector. However, this is logistically very difficult to accomplish in the field, and an ideal solution is to find a molecular surrogate for xenodiagnosis. In this review we discuss different approaches to the problem by focusing on the infectiousness of Leishmania (Viannia) braziliensis in rodents under laboratory and field conditions. Comparisons with similar studies for other Leishmania species emphasizes that there are pivotal differences in the infectiousness and the importance of asymptomatic infections in different hosts. Potentially the most promising surrogate is the real time quantitative PCR (qPCR). However, its success depends on choosing a tissue that relates to the vector's feeding location and the parasite's tissue tropism. This requires detailed knowledge of the infection of each species in its wild hosts. We conclude that for L. (V.) braziliensis infections in wild rodents the tissue of choice for a molecular xenodiagnostic test, based on the qPCR is blood, providing that a significant number of samples must be examined.

Chronic Chagas disease: PCR-xenodiagnosis without previous microscopic observation is a useful tool to detect viable Trypanosoma cruzi

We evaluate the elimination of the microscopic stage of conventional xenodiagnosis (XD) to optimize the parasitological diagnosis of Trypanosoma cruzi in chronic Chagas disease. To this purpose we applied under informed consent two XD cages to 150 Chilean chronic chagasic patients. The fecal samples (FS) of the triatomines at 30, 60 and 90 days post feeding were divided into two parts: in one a microscopic search for mobile trypomastigote and/or epimastigote forms was performed. In the other part, DNA extraction-purification for PCR directed to the conserved region of kDNA minicircles of trypanosomes (PCR-XD), without previous microscopic observation was done. An XD was considered positive when at least one mobile T. cruzi parasite in any one of three periods of incubation was observed, whereas PCR-XD was considered positive when the 330 bp band specific for T. cruzi was detected. 25 of 26 cases with positive conventional XD were PCR-XD positive (concordance 96.2%), whereas 85 of 124 cases with negative conventional XD were positive by PCR-XD (68.5%). Human chromosome 12 detected by Real-time PCR used as exogenous internal control of PCR-XD reaction allowed to discounting of PCR inhibition and false negative in 40 cases with negative PCR-XD. Conclusion: PCR-XD performed without previous microscopic observation is a useful tool for detection of viable parasites with higher efficiency then conventional XD.

Seroprevalencia de trypanosoma cruzi en perros de dos áreas endémicas de Colombia / Seroprevalencia de trypanosoma cruzi em cachorros de duas áreas endémicas da Colômbia / Seroprevalence of trypanosoma cruzi in dogs from two endemic areas of Colombia

La tripanosomiasis americana es una enfermedad antropozoonótica causada por Trypanosoma cruzi, parásito flagelado que se anida y se reproduce principalmente en el tejido cardíaco. Se encuentra ampliamente distribuida en el continente americano y en Colombia se estima que un 2% al 3% de la población está infectado y que cerca del 5% está bajo riesgo de adquirir la infección, debido a la amplia distribución de los insectos triatominos, sus vectores. El presente estudio reporta la seroprevalencia para T. cruzi en perros (Canis familiaris) de dos áreas rurales endémicas del departamento de Boyacá usando la técnica de inmunofluorescencia indirecta (IFI) y la caracterización molecular de las cepas aisladas. Se procesaron 261 muestras de sueros de perros de diferentes edades obtenidas en los municipios de Soatá y Berbeo. La detección de anticuerpos anti-T. cruzi se realizó mediante la técnica de inmunofluorescencia indirecta (IFI). Se realizó xenodiagnóstico a 185 perros con cuatro resultados positivos, de los que se aislaron tres cepas, caracterizadas molecularmente como T. cruzi 1 (TC-I) por medio de la amplificación del gene miniexon. Los análisis estadísticos mostraron asociaciones significativas entre características de las viviendas tales como el tipo de pared, techo, piso y presencia de anexos con el número de perros positivos para T. cruzi. Un total de 10,72% de los sueros procesados fueron positivos, 11,29% en Soatá y 9,5% en Berbeo. Este primer trabajo sobre prevalencia de perros infectados con T. cruzi en Colombia revela la importancia epidemiológica de estos animales como reservorios y la caracterización molecular de los aislados contribuye al entendimiento de la dinámica de transmisión del parásito...

American Trypanosomiasis is an antropozoonotic disease caused by the protozoan Trypanosoma cruzi. This protozoan widely distributed in the Americas invades and multiplies mainly in the cardiac tissue. In Colombia, 2%-3% of the population is infected with the parasite and nearly 5% is under risk due to the widely distribution of the triatomine vectors. This study reports in two endemic zones of Boyaca (Colombia) the prevalence of T. cruzi in dogs (Cannis familiaris) using indirect immunofluorescent antibody test (IFI) and the molecular characterization of strains isolated by xenodiagnosis. 261 sera from mongrel dogs of all ages where obtained from the locations of Soata and Berbeo. The detection of antibodies against T. cruzi was performed by IFI, xenodiagnosis was performed in 185 dogs. Four dogs resulted positive and three different strains were isolated and characterized as T. cruzi 1 (TC-I) by the miniexon gene amplification. Statistical analyses showed significant associations between house characteristics such as type of walls, ceiling and floor with the number of infected dogs. A total of 10,7% of all processed sera were positive, being 11,2% from Soata and 9,5% from Berbeo. This first approach to determine the prevalence of infected dogs with T. cruzi in Colombia reveals the epidemiological importance of dogs as reservoirs of this parasite that may help to batter understand the dynamics of the parasite transmission and life cycle...

A tripanossomose americana é uma doença antropozoonótica causada por Trypanosoma cruzi, parasito flagelado que se aninha e se reproduz principalmente no tecido cardíaco. Encontra-se amplamente distribuída no continente americano e em Colômbia se estima que um 2% ao 3% da população está infectado e que cerca do 5% está sob risco de adquirir a infecção, devido à ampla distribuição dos insetos triatominos, seus vetores. O presente estudo reporta a seroprevalência para T. cruzi em cachorros (Canis familiaris) de duas áreas rurais endêmicas do departamento de Boyacá e a caracterização molecular das cepas isoladas. Se processaram 261 mostras de soros de cachorros de diferentes idades obtidas nos municípios de Soatá e Berbeo. A detecção de anticorpos anti-T. cruzi se realizou mediante a técnica de inmunofluorescencia indireta (IFI). Se realizou xenodiagnóstico a 185 cachorros com quatro resultados positivos, dos que se isolaram três cepas, caracterizadas molecularmente como TC I por meio da amplificação do gene miniexon. As análises estatísticas mostraram associações significativas entre características das moradias tais como o tipo de parede, teto, andar e presença de anexos com o número de cachorros positivos para T. cruzi. Um total de 10,72% dos soros processados foram positivos, 11,29% em Soatá e 9,5% em Berbeo. Este primeiro trabalho sobre prevalência de cachorros infectados com T. cruzi em Colômbia revela a importância epidemiológica destes animais como reservatórios e a caracterização molecular dos isolados contribui ao entendimento da dinâmica de transmissão do parasita...

Aspectos parasitológicos y epidemiológicos de los donantes de sangre seropositivos para Trypanosoma cruzi, en un hospital universitario / Parasitological and epidemiological aspects of Trypanosoma cruzi seropositive blood donors

Background: After the interruption of the transmission of Chagas disease via vector insects in Chile, there is little available epidemiological information about this parasitosis in blood banks. Aim To update the rates of T cruzi positive blood donors. To measure parasitological and epidemiological parameters in blood donors with anti T cruzi antibodies. Material and Methods: An ELISA-T cruzi test was carried out in 30,309 blood donors between 2000 and 2004. In 75 blood donors with an ELISA-T cruzi positive test and 79 donors with negative ELISA (controls), a survey about personal or parental history of biting by a kissing bug (Triatomine), was performed. A blood sample was also obtained to perform Polymerase Chain Reaction (PCR) for T cruzi and a xenodiagnostic test. Results: Annual frequency of positive ELISA for T cruzi serum antibodies in blood donors varied from 0.31 percent to 0.45 percent. Twenty eight percent of subjects with positive and 6 percent of subjects with negative specific antibodies answered the survey about biting. PCR and xenodiagnostic test were positive in 52 (69 percent) and 16 (21 percent) of positive ELISA-T cruzi test blood donors, respectively. Xenodiagnostic was also positive in 5 individuals who had a negative PCR. Conclusions: Seroprevalence of T cruzi antibodies decreased from 3 percent in 1968 to 0.3 percent in 2004.

Comparação entre o xenodiagnóstico clássico e artificial na fase crônica da doença de Chagas / Comparison between classical and artificial xenodiagnosis in chronic Chagas disease

Classical and artificial xenodiagnostic techniques made with Dipetalogaster maximus of first stage were performed simultaneously in 57 patients with chronic T. cruzi infection (22 male and 35 female patients, aged 7-80 years). With the exception of two patients with megaoesophagus, all had two previous positive serological reaction and a further test was done at the time of the examination. The patients came from the outpatient department of the university hospital or were resident in Mambaí, Goiás. Of the 57 patients, 24 (42%) had a positive xenodiagnoses. Of a total of 114 tests performed, 36(32%) were positive. Comparing the two xenodiagnostic techniques, no significant advantage was apparent statistically (p = 0.42), but the artificial technique has advantages because the blood is offered for triatomines through a device while in the classical technique, the triatomines suck through the patient's skin.

O xenodiagnóstico (xeno) clássico e artificial feitos com Dipatalogaster maximus de primeiro estágio foi realizado simultaneamente em 57 pacientes com infecção chagásica crônica (22 do sexo masculino e 35 do sexo feminino, com idades entre 7 e 80 anos). Exceto dois pacientes com clínica de megaesôfago, os demais tinham dois exames sorológicos prévios positivos sendo feita nova sorológia no decorrer do estudo. Os pacientes eram provenientes do ambulatório do Hospital Universitário de Brasília (HUB) ou eram residentes no município de Mambaí, GO. Dos 57 pacientes, 24 (42%) apresentaram xenodiagnósticos positivos. Dos 114 xenodiagnósticos realizados, 36 (32%) foram positivos. A comparação das duas técnicas não mostrou diferença estatisticamente significante (p = 0,42), porém o xeno artificial apresenta vantagem porque o sangue é oferecido aos triatomíneos através de um aparelho enquanto, no xeno clássico, os triatomíneos sugam através da pele do paciente