Factors associated with peridomestic Triatoma sanguisuga (Hemiptera: Reduviidae) presence in southeastern Louisiana.

Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human case of domestically transmitted T. cruzi was identified in southern Louisiana. To examine the localized risk of human T. cruzi infection in the area surrounding the initial human case, environmental surveys of households in the area and a serological survey of the residents were performed between September 2008 and November 2009. Human T. cruzi infection was determined using a rapid antigen field test, followed by confirmatory enzyme-linked immunosorbent assay testing in the laboratory. A perimeter search of each participating residence for Triatoma sanguisuga (LeConte), the predominant local triatomine species, was also performed. No participating individuals were positive for antibodies against T. cruzi; however, high levels of T. cruzi infection (62.4%) were detected in collected T. sanguisuga. Households with T. sanguisuga presence were less likely to use air conditioning, and more likely to have either chickens or cats on the property. While the human risk for T cruzi infection in southeastern Louisiana is low, a high prevalence of infected T. sanguisuga does indicate a substantial latent risk for T. cruzi peridomestic transmission. Further examination of the behavior and ecology of T. sanguisuga in the region will assist in refining local T. cruzi risk associations.

Effect of dengue-2 virus infection on protein expression in the salivary glands of Aedes aegypti mosquitoes.

Dengue virus (DENV) is the most important mosquito-transmitted flavivirus that is transmitted throughout the tropical and subtropical regions of the world. The primary mosquito vector of DENV in urban locations is Aedes aegypti. Key to understanding the transmission of DENV is the relationship between pathogen and vector. Accordingly, we report our preliminary characterization of the differentially expressed proteins from Ae. aegypti mosquitoes after DENV infection. We investigated the virus-vector interaction through changes in the proteome of the salivary glands of mosquitoes with disseminated DENV serotype 2 (DENV-2) infections using two-dimensional gel electrophoresis and identification by mass spectrometry. Our findings indicate that DENV-2 infection in the Ae. aegypti salivary gland alters the expression of structural, secreted, and metabolic proteins. These changes in the salivary gland proteome highlight the virally influenced environment caused by a DENV-2 infection and warrant additional investigation to determine if these differences extend to the expectorated saliva.

Chloroquine-resistant haplotype Plasmodium falciparum parasites, Haiti.

Plasmodium falciparum parasites have been endemic to Haiti for >40 years without evidence of chloroquine (CQ) resistance. In 2006 and 2007, we obtained blood smears for rapid diagnostic tests (RDTs) and filter paper blots of blood from 821 persons by passive and active case detection. P. falciparum infections diagnosed for 79 persons by blood smear or RDT were confirmed by PCR for the small subunit rRNA gene of P. falciparum. Amplification of the P. falciparum CQ resistance transporter (pfcrt) gene yielded 10 samples with amplicons resistant to cleavage by ApoI. A total of 5 of 9 samples had threonine at position 76 of pfcrt, which is consistent with CQ resistance (haplotypes at positions 72-76 were CVIET [n = 4] and CVMNT [n = 1]); 4 had only the wild-type haplotype associated with CQ susceptibility (CVMNK). These results indicate that CQ-resistant haplotype P. falciparum malaria parasites are present in Haiti.

Prevalence of Plasmodium falciparum infection in rainy season, Artibonite Valley, Haiti, 2006.

We conducted a population-based survey to estimate the prevalence of Plasmodium falciparum infection among persons older than 1 month in the Artibonite Valley of Haiti during the high malaria transmission season in 2006. Results from PCR for 714 persons showed a prevalence of 3.1% for P. falciparum infection.

Prevention of sporogony of Plasmodium vivax in Anopheles albimanus by steroids of Solanum nudum Dunal (Solanaceae).

The sporontocidal activity of three steroids (SN-1, SN-2 and SN-4) from Solanum nudum Dunal (Solanaceae) was determined against naturally circulating isolates of Plasmodium vivax in Anopheles albimanus. Laboratory-reared Anopheles albimanus mosquitoes were infected with P. vivax from gametocytemic blood of volunteers resident in Buenaventura, Valle del Cauca (Colombian Pacific Coast) by using an artificial membrane feeder. Prior to mosquito feeding, gametocytemic blood was centrifuged, plasma was separated, packed blood red cells were washed with RPMI 1640 and then resuspended in non-immune AB serum, then the steroids were added at different doses. On day 7 after infection, the presence and number of oocysts in mosquitoes was determined. The steroid SN-2 reduced the infection of mosquitoes by 90% and the mean number of oocysts by 60%. These data confirmed that the experimental steroid is capable of interrupting the sporogonic development of P. vivax in Anopheles albimanus. This experimental steroid has potential for transmission blocking in vivax malaria.

Effect of Solanum nudum Dunal (Solanaceae) steroids on hepatic trophozoites of Plasmodium vivax.

Steroids isolated from the plant Solanum nudum showed antiplasmodial activity against the blood stages of Plasmodium falciparum. It has been demonstrated that these steroids are neither mutagenic in vitro nor clastogenic in vivo. This study evaluated the effect of five steroids of S. nudum (SN-1, SN-2, SN-3, SN-4 and SN-5) on hepatic trophozoites of P. vivax, using an experimental design, non-balanced, with blind determination of the effect expressed as the percentage reduction of hepatic trophozoites. The sporozoites used to inoculate human hepatoma cells HepG2-A16 were obtained from gametocytemic blood of volunteers infected only with P. vivax, and passed into laboratory-reared Anopheles albimanus mosquitoes. Steroids were added at three different doses (100, 10 and 1 microg/mL) just after inoculation of the cells with sporozoites. The effect was determined by indirect immunofluorescence assays using the monoclonal antibodies Pv210 or Pv47E-2E10 and steroid cytotoxicity on HepG2-A16 cells was assessed by the MTT method. All the steroids reduced the number of hepatic P. vivax trophozoites, SN-2 and SN-4 reduced the number of hepatic trophozoites by 47% and 39% (p < 0.05), respectively.

Comparación de los métodos Optimal y gota gruesa para el diagnóstico de la malaria en una zona endémica sin epidemia / Compararison between Optimal and thick smear tests for malaria diagnosis in an endemic area during a non-epidemic period

En Turbo, Antioquía, entre junio y agosto de 2000, se evaluó la capacidad diagnóstica de Optimal(c) frente a la gota gruesa, en dos muestras representativas de las poblaciones de consultantes al puesto de diagnóstico de malaria: uno con síndrome febril agudo (SFA) n107, y otro con malaria diagnosticada por gota gruesa (SFAM) n82. Se usó un diseño descriptivo, prospectivo y transversal. Las dos pruebas se aplicaron en forma simultánea o paralela en el grupo (SFA) y en forma secuencial en el grupo (SFAM). La gota gruesa fue la prueba estándar. Optimal (c) se usó según las instrucciones del fabricante. El grupo SFA se estudió con diseño ciego. Con diseño paralelo, Optimal(c) tuvo para Plasmodium falciparum, una sensibilidad de 40 por ciento (intervalo de confianza del 95 por ciento (IC 95 por ciento: 18-67), especificidad de 98 por ciento (IC 95 por ciento: 92-100), valores predictivos positivo y negativo de 75 por ciento (IC 95 por ciento: 36-96) y 91 por ciento (IC 95 por ciento: 83-96 por ciento). Para Plasmodium vivax mostró sensibilidad de 97 por ciento (IC 95 por ciento: 82-100), especificidad de 89 por ciento (IC 95 por ciento: 80-95), valores predictivos positivo y negativo de 79 por ciento (IC 95 por ciento: 62-90) y 98 por ciento (IC 95 por ciento: 91-100). Con diseño secuencial, Optimal(c) tuvo sensibilidad de 67 por ciento (IC 95 por ciento: 52-79) para P. falciparum y 97 por ciento (IC 95 por ciento: 83-100) para P. vivax. Para P. falciparum, la sensibilidad fue directamente proporcional a la parasitemia, mientras que para P. vivax la sensibilidad fue independiente de la parasitemia. Por sus valores diagnósticos y sus características operativas, la gota gruesa supera ampliamente a Optimal(c) en sensibilidad para P. falciparum, aunque fue similar en especificidad y ambas pruebas son iguales en diagnóstico de P. vivax. La gota gruesa debe conservarse como la prueba de rutina y de referencia para el diagnóstico de malaria y Optimal (c) como una prueba auxiliar.

[Comparison between OptiMAL and the thick smear tests for malaria diagnosis in an endemic area during a non-epidemic period]. / Comparación de los métodos Optimal y gota gruesa para el diagnóstico de malaria en una zona endémica sin epidemia.

The capacity of Optimal to diagnose malaria was compared with the thick smear test in two representative samples, one with acute febrile syndrome (AFS) n = 107, and another diagnosed by thick smear test (AFS + M) n = 82. The samples were chosen from patients at the malaria diagnostic clinic in Turbo, Antioquia, Colombia, between June and August 2000. The study was designed to be descriptive, prospective, and cross-sectional. The two tests were applied simultaneously in the AFS group (parallel, double blind design), and in sequential form in the AFS + M group. The thick smear test was the standard test. Optimal tests were carried out according to the manufacturer's instructions. In the parallel design, Optimal showed, for Plasmodium falciparum, a sensitivity of 40% [95% CI: 18-67], a specificity of 98% (95% CI: 92-100) and positive and negative predictive values of 75% (95% CI: 36-96) and 91% (95% CI: 83-96%), respectively. For Plasmodium vivax, it showed a sensitivity of 97% (95% CI: 82-100), a specificity of 89% (95% CI: 80-95) and positive and negative predictive values of 79% (95% CI: 62-90) and 98% (95% CI: 91-100). With the sequential design, Optimal showed a sensitivity of 67% (95% CI: 52-79) and 97% (95% CI: 83-100) for P. falciparum and P. vivax, respectively. For P. falciparum, the sensitivity was directly proportional to the parasitemia, while the sensitivity for P. vivax was independent from the parasitemia. The diagnostic values and operative characteristics of the thick smear test surpassed the Optimal test in its sensitivity for P. falciparum; the specificities were similar. Both tests were nearly identical in their diagnostic capacity for P. vivax. These results recommend that the thick smear test be retained as a routine or reference test for malaria diagnosis, with Optimal used as an ancillary test.

Malaria y laboratorio / Malaria and laboratory

en zonas rurales, la falta de recursos como microscopios, personal capacitado, infraestructura eléctrica y reactivos necesarios para la realización de la gota gruesa -prueba estándar para el diagnóstico de la malaria- han incidido en el retLa gota gruesa presenta una sensibilidad del 80 por ciento y una especificidad del 100 por ciento cuando es realizada por un microscopista con experiencia, pero con bajas parasitemias (<500 parásitos/mL) estos casos se diagnostican como negativos, por esta razón la Organización Mundial de la Salud (OMS) ha planteado la necesidad de establecer métodos de diagnóstico rápidos, sensibles y específicos que permitan identificar individuos afectados con bajas parasitemias y que sean de bajo costo. Actualmente, se cuenta con nuevas técnicas: QBC, PCR, naranja de acridina y también con dos métodos de diagnóstico rápidos que son Parasight-F y OptiMAL. En este artículo se describen en forma breve estos métodosraso del diagnóstico y el tratamiento de la malaria