Epidemiology of Chagas disease in Guatemala: infection rate of Triatoma dimidiata, Triatoma nitida and Rhodnius prolixus (Hemiptera, Reduviidae) with Trypanosoma cruzi and Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae).

A five-year domiciliary collection in the 22 departments of Guatemala showed that out of 4,128 triatomines collected, 1,675 were Triatoma dimidiata (Latreille, 1811), 2,344 were Rhodnius prolixus Stal 1859, and only 109 were T. nitida Usinger 1939. The Chagas disease parasite, Trypanosoma cruzi, was found in all three species. Their natural infection rates were similar in the first two species (20.6%; 19.1%) and slightly lower in T. nitida(13.8%). However there was no significant difference in the infection rates in the three species (p = 0.131). T. dimidiata males have higher infection rates than females (p = 0.030), whereas for R. prolixus there is no difference in infection rates between males and females (p = 0.114). The sex ratios for all three species were significantly skewed. More males than females were found inside houses for T. dimidiata (p < 0.0001) and T. nitida (p = 0.011); a different pattern was seen for R. prolixus (p = 0.037) where more females were found. Sex ratio is proposed as an index to show the mobility of T. dimidiata in different populations. T. dimidiata is widely distributed in the country, and is also the main vector in at least ten departments, but R. prolixus with higher vectorial capacity is an important vector in at least two departments.

Geographic distribution and morphometric differentiation of Triatoma nitida usinger 1939 (Hemiptera: Reduviidae: Triatominae) in Guatemala.

Triatoma nitida was found in 14 (0.4%) out of 3,726 houses located in six departments across Guatemala, which were surveyed from 1994 to 1998 by the man-hour collection method. Compared to previous information, the distribution of T. nitida in Guatemala has increased from five to nine departments; the species is present in mild climates at altitudes from 960 to 1,500 m. Fourteen percent of the intradomestic T. nitida were infected with Trypanosoma cruzi. The species was often found in conjunction with other triatomines (T. dimidiata and Rhodnius prolixus). The domestic and peridomestic presence of T. nitida in Guatemala was rare, but occasionally this species was colonizing human-made constructions. T. nitida appears to have a low importance as Chagas disease vector in Guatemala, as indicated by its scarce presence in the domestic habitats and defecation patterns. However, it clearly has potential to become a Chagas vector so we recommend an on-going study of the intradomestic presence of T. nitida following the control programs in Guatemala. Morphometric analysis of 47 T. nitida males from three localities showed quantitative differences between the populations, which indicates that geographic distance is an important factor in the structuring of T. nitida populations.

Epidemiology of Chagas disease in Guatemala: infection rate of Triatoma dimidiata, Triatoma nitida and Rhodnius prolixus (Hemiptera, Reduviidae) with Trypanosoma cruzi and Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae)

A five-year domiciliary collection in the 22 departments of Guatemala showed that out of 4,128 triatomines collected, 1,675 were Triatoma dimidiata (Latreille, 1811), 2,344 were Rhodnius prolixus Stal 1859, and only 109 were T. nitida Usinger 1939. The Chagas disease parasite, Trypanosoma cruzi, was found in all three species. Their natural infection rates were similar in the first two species (20.6 percent; 19.1 percent) and slightly lower in T. nitida(13.8 percent). However there was no significant difference in the infection rates in the three species (p = 0.131). T. dimidiata males have higher infection rates than females (p = 0.030), whereas for R. prolixus there is no difference in infection rates between males and females (p = 0.114). The sex ratios for all three species were significantly skewed. More males than females were found inside houses for T. dimidiata (p < 0.0001) and T. nitida (p = 0.011); a different pattern was seen for R. prolixus (p = 0.037) where more females were found. Sex ratio is proposed as an index to show the mobility of T. dimidiata in different populations. T. dimidiata is widely distributed in the country, and is also the main vector in at least ten departments, but R. prolixus with higher vectorial capacity is an important vector in at least two departments

Phylogenetic relationships among JC virus strains in Japanese/Koreans and Native Americans speaking Amerind or Na-Dene.

Many genetic studies using human mtDNA or the Y chromosome have been conducted to elucidate the relationships among the three Native American groups speaking Amerind, Na-Dene, and Eskimo-Aleut. Human polyomavirus JC (JCV) may also help to gain insights into this issue. JCV isolates are classified into more than 10 geographically distinct genotypes (designated subtypes here), which were generated by splits in the three superclusters, Types A, B, and C. A particular subtype of JCV (named MY) belonging to Type B is spread in both Japanese/Koreans and Native Americans speaking Amerind or Na-Dene. In this study, we evaluated the phylogenetic relationships among MY isolates worldwide, using the whole-genome approach, with which a highly reliable phylogeny of JCV isolates can be reconstructed. Thirty-six complete sequences belonging to MY (10 from Japanese/Koreans, 24 from Native Americans, and 2 from others), together with 54 belonging to other subtypes around the world, were aligned and subjected to phylogenetic analysis using the neighbor-joining and maximum-likelihood methods. In the resultant phylogenetic trees, the MY sequences diverged into two Japanese/Korean and five Native American clades with high bootstrap probabilities. Two of the Native American clades contained isolates mainly from Na-Denes and the others contained isolates mainly from Amerinds. The Na-Dene clades were not clustered together, nor were the Amerind clades. In contrast, the two Japanese/Korean clades were clustered at a high bootstrap probability. We concluded that there is no distinction between Amerinds and Na-Denes in terms of indigenous JCVs, although they are linguistically distinguished from each other.

Geographic distribution and morphometric differentiation of Triatoma nitida usinger 1939 (Hemiptera: Reduviidae: Triatominae) in Guatemala

Triatoma nitida was found in 14 (0.4 percent) out of 3,726 houses located in six departments across Guatemala, which were surveyed from 1994 to 1998 by the man-hour collection method. Compared to previous information, the distribution of T. nitida in Guatemala has increased from five to nine departments; the species is present in mild climates at altitudes from 960 to 1,500 m. Fourteen percent of the intradomestic T. nitida were infected with Trypanosoma cruzi. The species was often found in conjunction with other triatomines (T. dimidiata and Rhodnius prolixus). The domestic and peridomestic presence of T. nitida in Guatemala was rare, but occasionally this species was colonizing human-made constructions. T. nitida appears to have a low importance as Chagas disease vector in Guatemala, as indicated by its scarce presence in the domestic habitats and defecation patterns. However, it clearly has potential to become a Chagas vector so we recommend an on-going study of the intradomestic presence of T. nitida following the control programs in Guatemala. Morphometric analysis of 47 T. nitida males from three localities showed quantitative differences between the populations, which indicates that geographic distance is an important factor in the structuring of T. nitida populations

Validez de las tinciones de Giemsa y Lendrum en frotis conjuntivales para la identificación de Chlamydia trachomatis / Validity of Giemsa and Lendrum stains in conjunctival smears for the identification of Chlamydia trachomatis

Con el oobjeto de encontrar pruebas diagnósticas confiables, válidas y económicas para identificar Chlamydia trachomatis en frotes conjuntivales, se evaluó la sensibilidad, especificidad y los valores predictivos positivo y negativo de las tinciones de Lendrum y Giemsa empleando como prueba de oro la inmunofluorescencia directa. Asimismo, se estimó la reproducibilidad inter e intraobservador empleando dos observadores independientes. Las lecturas se efectuaron a ciegas. La prevalencia de clamidiasis ocular en la zona del estudio oscilaba alrededor de 50 por ciento. En total se estudiaron 103 personas (206 ojos). A cada una se le hicieron frotis de cada ojo. Para estimar la reproducibilidad de las tinciones, se empleó el estadístico kappa. La reproducibilidad interobservador fue nula y la reproducibilidad intraobservador varió entré 0,35 y 0,79. La sensibilidad de la tinción de Giemsa es un poco más alta que la de Lendrum (28 por ciento y 22 por ciento respectivamente), y la especificidad, similiar (82 por ciento y 85 por ciento), respectivamente). Por consiguiente, la capacidad de ambas tinciones para detectar casos positivos es baja, así como su confiabilidad. Las tinciones de Lendrum y Giemsa no constituyen pruebas adecuadas para el diagnóstico de clamidiasis ocular. Para este propósito se recomienda utilizar la inmunofluorescencia directa

Validez de las tinciones de Giemsa y Lendrum en frotis conjuntivales para la identificación de Chlamydia trachomatis / Validity of Giemsa and Lendrum stains in conjunctival smears for the identification of Chlamydia trachomatis

Con el oobjeto de encontrar pruebas diagnósticas confiables, válidas y económicas para identificar Chlamydia trachomatis en frotes conjuntivales, se evaluó la sensibilidad, especificidad y los valores predictivos positivo y negativo de las tinciones de Lendrum y Giemsa empleando como prueba de oro la inmunofluorescencia directa. Asimismo, se estimó la reproducibilidad inter e intraobservador empleando dos observadores independientes. Las lecturas se efectuaron a ciegas. La prevalencia de clamidiasis ocular en la zona del estudio oscilaba alrededor de 50 por ciento. En total se estudiaron 103 personas (206 ojos). A cada una se le hicieron frotis de cada ojo. Para estimar la reproducibilidad de las tinciones, se empleó el estadístico kappa. La reproducibilidad interobservador fue nula y la reproducibilidad intraobservador varió entré 0,35 y 0,79. La sensibilidad de la tinción de Giemsa es un poco más alta que la de Lendrum (28 por ciento y 22 por ciento respectivamente), y la especificidad, similiar (82 por ciento y 85 por ciento), respectivamente). Por consiguiente, la capacidad de ambas tinciones para detectar casos positivos es baja, así como su confiabilidad. Las tinciones de Lendrum y Giemsa no constituyen pruebas adecuadas para el diagnóstico de clamidiasis ocular. Para este propósito se recomienda utilizar la inmunofluorescencia directa