Review of biological and diagnostic aspects of Trypanosoma (Herpetosoma) rangeli

This review has three objectives: a) To stimulate further research of this prevalent human infection b) to examine the progress of current diagnostic techniques and c) to emphasise the significance of the flagellate parasite Trypanosoma (Herpetosoma) rangeli in Chagas' Disease endemic areas of South and Central America. Both Trypanosoma rangeli and Trypanosoma cruzi overlap in many of the areas of Latin America utilising the same triatomine vectors. Also a vast range of mammalian species have been found naturally infected with T. rangeli . The biology of the parasitism of T. rangeli is revised and emphasis is given regarding its biological cycle. T. cruzi and T. rangeli share common antigens and cross react serologically. Human infection in the chronic phase may be misdiagnosed as T. cruzi infection. Conventional and modern diagnostic and identification methods are discussed. Unfortunately we do not know the real distribution of T. rangeli infections in most areas and epidemiological studies to examine concomitant dual infections deserve further investigation.Esta revisión tiene tres objetivos básicos: a) estimular aún más la investigación de esta prevalente infección humana. b) examinar el arsenal de técnicas diagnósticas disponíbles al momento y, las nuevas pruebas descritas recientemente. c) enfatizar el significado que tiene, el parasitismo por el Trypanosoma (Herpetosoma) rangeli, en las áreas endémicas de la Enfermedad de Chagas distribuidas en las Américas Central y del Sur. Trypanosoma rangeli y Trypanosoma cruzi son parásitos que circulan superponiéndose en muchas áreas de Latinoamérica utilizando prácticamente los mismos triatominos vectores. Una vasta gama de especies de mamíferos han sido encontradas infectadas naturalmente con T. rangeli en diversos países. Se revisa la biología del parasitismo y el ciclo biológico del tripanosoma haciendo énfasis en este último. Infecciones crónicas por T. rangeli en el hombre pueden, serológicamente, ser confundidas con las del T. cruzi. Ambas especies presentan antígenos comunes que provocan las conocidas reacciones serológicas cruzadas. Desafortunadamente, no conocemos la real distribución de las infecciones por el T. rangeli en la mayoría de las áreas mencionadas. Nuevos estudios epidemiológicos son necesarios, para examinar el problema de las infecciones humanas mixtas, por estos tripanosomas

Infestation of thornbird nests (Passeriformes: Furnariidae) by Psammolestes tertius (Hemiptera: Reduviidae) across Brazilian Cerrado and Caatinga ecoregions

Psammolestes tertius Lent & Jurberg, 1965 is a sylvatic triatomine bug species that occurs in thornbird nests in Brazil. We studied infestation of 527 nests of Phacellodomus rufifrons Wied, 1821 and Phacellodomus ruber Vieillot, 1817 by P. tertius in eight Brazilian states across the Cerrado and Caatinga ecoregions. Psammolestes tertius occurred in 44% of the nests, mainly in those of P. ruber. Overall, 3,261 specimens (52% nymphs) were captured, with an average of 14 bugs per infested nest (range 1-75). While P. tertius occurrence and age structure (percentage of nymphs) were similar in Cerrado and Caatinga nests, infestation intensity (bugs/infested nest) was higher in the Cerrado. Last-stage nymphs and adults were predominant in P. tertius populations from both P. ruber and P. rufifrons nests. The results indicate that Phacellodomus nests are favourable habitats for P. tertius in the open/dry ecoregions of Brazil. The percentage of adult P. tertius specimens (48%) was higher than that observed in other triatomine species (usually less than 5% under either experimental or natural conditions), suggesting that adult bugs tend to remain in thornbird nests. The stable blood supply provided by resident/breeding birds would favor steady P. tertius infestation of thornbird nests across Brazilian Cerrado and Caatinga ecoregions

Triatomines (Hemiptera, Reduviidae) prevalent in the northwest of Peru: species with epidemiological vectorial capacity

ABSTRACT: The development of strategies for the adequate control of the vector transmission of Chagas disease depends on the availability of updated data on the triatomine species present in each region, their geographical distribution, natural infections by Trypanosoma cruzi and/or T. rangeli, eco-biological characteristics and synanthropic behavioral tendencies. This paper summarizes and updates current information, available in previously published reports and obtained by the authors our own field and laboratory studies, mainly in northwest of Peru. Three triatomine species exhibit a strong synanthropic behavior and vector capacity, being present in domestic and peridomestic environments, sometimes showing high infestation rates: Rhodnius ecuadoriensis, Panstrongylus herreri and Triatoma carrioni The three species should be given continuous attention by Peruvian public health authorities. P. chinai and P. rufotuberculatus are bugs with increasing potential in their role as vectors according to their demonstrated synanthropic tendency, wide distribution and trophic eclecticism. Thus far we do not have a scientific explanation for the apparent absence ofT. dimidiata from previously reported geographic distributions in Peru. It is recommended, in the Peruvian northeastern Amazon region, the development of field studies on species of the genus Rhodnius, as well as of other triatominae, to evaluate their present Trypanosomatidae vector capacity. _______________________________________________________________________________________ RESUMENEl desarrollo de estrategias adecuadas para el control de la transmisión vectorial de la Enfermedad de Chagas depende: de la disponibilidad de datos actualizados de las especies de triatominos presentes en cada región, de su distribución geográfica, infección natural por Trypanosoma cruzi ylo T. rangeli, características eco-biológicas y tendencias de comportamiento sinantrópico. Este trabajo resume y actualiza la información disponible en la literatura y aquella obtenida en nuestros estudios de campo y de laboratorio desarrollados en los últimos años por los autores, predominantemente, en la región Nor-Occidental del Perú. El resultado de esas observaciones es la detección de que, tres especies de triatominos presentan un importante comportamiento sinantrópico y capacidad vectorial, ocupando ambientes intradomiciliares y peridomiciliares: Rhodnius ecuadoriensis, Panstrongylus herreriy Triatoma carrioni. Las tres especies deben recibir constante atención por parte de las autoridades de Salud Pública Peruana. P. chinai y P rufotuberculatus tienen potencial creciente en su papel de vectores, por la comprobada tendencia sinantrópica, distribución geográfica y eclecticismo trófico. Se desconocen las causas de la aparente ausencia actual de Triatoma dimidiata, dada su presencia constatada anteriormente en el Perú. Se recomienda que en la región Nor-Oriental Amazónica Peruana se realicen en forma urgente estudios sobre las especies del genero Rhodnius y de otros triatominos que permitan evaluar la real capacidad vectorial de los Trypano-somatideos

Domestic Rhodnius ecuadoriensis (Hemiptera, Reduviidae) infestation in Northern Peru: a comparative trial of detection methods during a six-month follow-up

Two passive methods in the assessment of intradomiciliary infestation by Rhodnius ecuadoriensis were tested: (i) the Gomes Nuñez sensor box (GN), (ii) sheets of white typing paper and (iii) one active timed manual method. The study was carried out in the Alto Chicama River Valley, Province of Gran Chimú, Department of La Libertad. The study design consisted of an initial searching of triatomines inside of the domestic environment by the manual capture active procedure (man/hour) covering all the studied houses. Then, matched pairs of GN boxes and paper sheets were simultaneously installed in the bedrooms of 207 households distributed in 19 localities. A comparative prospective trial of these passive detection devices were monitored at 2, 4 and, finally 6 months follow-up. Parasitological Trypanosoma rangeli and/or T. cruzi infections were investigated in two houses with high level of infestation by R. ecuadoriensis.16.9% of the 207 households investigated by an initial active manual method were infested with R. ecuadoriensis. The proportion of infested houses fluctuated from 6.2 to 55.5% amongst the 19 localities investigated. T. rangeli natural infection was detected in R.ecuadoriensis specimens collected in two households. Parasite rates in the bugs ranged from 16.6 to 21.7% respectively. The most striking fact was an average rate of salivary gland infection ranging from 7.4 to 8.3%. At the end of the sixth month period, a cumulative incidence of 31.4% of positive GN boxes against 15.9% for paper sheets was recorded. All three methods combined detected domestic infestation in 129 (62.3%) of the 207 houses studied in the 19 localities. The range of houses infested varies from 6.7% to 92.9%. In areas with low bug density infestation rates, the methodology experienced in our studies, seems to be the best choice for investigations on domestic R. ecuadoriensis populations

Artrópodos Associados à Copa da Palmeira Mauritia flexuosa (Arecaceae) em três ambientes diferentes no Cerrado Brasileiro

Artrópodos associados à copa de árvores, principalmente palmeiras, são pouco conhecidos no Cerrado. Para descrever a estrutura da comunidade de artrópodos à copa de Mauritia flexuosa (Arecaceae) foram amostradas 150 palmeiras em seis veredas” do Distrito Federal, de áreas silvestres, rurais e periurbanas na estação chuvosa. Os artrópodos presentes nos ninhos abandonados de aves, refúgios de mamíferos, folhas e matéria orgânica foram coletados manualmente, fixados em etanol 70% e separados em ordem, família, morfoespécie e guildas alimentares. As características das palmeiras medidas foram altura da estipe, diâmetro da copa, número de folhas e de ninhos de aves nas palmeiras. Foram coletados 3.862 indivíduos, pertencentes a 15 ordens, 45 famílias e 135 morfoespécies. As ordens mais abundantes foram Coleoptera (28,6%), Blattodea (21,8%), Collembola (11,4%) e Hemiptera (10,2%). As famílias Blaberidae, Tenebrionidae, Entomobryidae, Reduviidae, Oniscidae, Staphylinidae, Carabidae e Formicidae representaram 82,1% de todos os indivíduos coletados. A maioria das morfoespécies foi pouco abundante, 71 (52,6%) apresentaram uma abundância média igual ou menor que 1 indivíduo/palmeira. Coleoptera compreendeu o maior número de morfoespécies (43,7%) seguida de Araneae (20,0%). A análise das guildas alimentares mostrou prevalência de predadores e hematófagos (36,0%). A riqueza e a abundância de artrópodos foram menores no ambiente periurbano. O número de ninhos de aves apresentou correlação positiva com abundância e riqueza, o que não ocorreu com as medidas das palmeiras. A importância de M. flexuosa para a manutenção da artropodofauna nas “veredas” no bioma Cerrado é discutida. _______________________________________________________________________________________ ABSTRACTCanopy arthropods, mainly from palm trees, are little known in the Brazilian Cerrado. In order to describe the arthropod community structure associated with the crown of Mauritia flexuosa (Arecaceae), we sampled 150 palm trees in six “veredas” of the Federal District, Brazil, in wild, rural and periurban areas in the rainy season. The arthropods within abandoned bird nests, mammal refuges, leaves and organic matter were manually collected, preserved in ethanol 70% and separated by order, family, morphospecies and feeding guilds. Stem height and diameter of the palm crowns were measured and leaves and bird nests were counted. We collected 3,862 arthropods, from 15 orders, 45 families and 135 morphospecies. The most abundant orders were Coleoptera (28.6%), Blattodea (21.8%), Collembola (11.4%) and Hemiptera (10.2%). The families Blaberidae, Entomobryidae, Reduviidae, Oniscidae, Staphylinidae, Carabidae and Formicidae, represented 82.1% of all individuals collected. The majority of morphospecies was not abundant, 71 (52.6%) were represented by less than 1 individual/tree. Coleopterans accounted for the highest number of morphospecies (43.7%) followed by Araneae (20.0%). The analysis of the arthropod feeding guilds showed prevalence of predatory/hematophagous ones (36.0%). Arthropod richness and abundance presented smaller values for periurban environment. The number of bird nests presented positive correlation with abundance and richness; this was not found when considering the measurements of the palm trees. The importance of M. flexuosa for the maintenance of the arthropod fauna of the “veredas” in Cerrado biome is discussed

Comparative study of parasitological techniques for demonstration of amastigotes and primary isolation of promastigotes in American Cutaneous leishmaniasis

FUNDAMENTOS: O PCR tem alta sensibilidade no diagnóstico da LTA, mas é caro e distante da prática. A cultura e o esfregaço são práticos, mas pouco sensíveis. OBJETIVO: O objetivo deste trabalho foi comparar os dois últimos métodos, buscando maior sensibilidade e menor custo. MÉTODOS:Foram comparados três meios de cultura no isolamento de leishmânia: Difco agar sangue + Schneider + soro bovino fetal (20%); Difco agar sangue + Schneider + urina humana (2%); Schneider + urina humana (2%). Foram comparadas, também, duas técnicas de pesquisa de amastigotas: esfregaço realizado com biópsia, ou raspado através de palito (matchstick). RESULTADOS: Os índices de positividade e contaminação (29 a 33% e 8 a 11%, respectivamente, p>0.05) foram semelhantes na comparação dos cultivos. Os esfregaços com biópsia, ou palito também não tiveram diferenças significativas (14 e 19%, respectivamente, p> 0,05). A Leishmania (Viannia) braziliensis predominou. CONCLUSÃO: No Brasil, a urina pode substituir o soro fetal bovino. Há vantagem na relação custo/benefício. A urina não tem custo enquanto 500ml de soro bovino fetal custa 185 dólares.BACKGROUND: PCR is a highly sensitive procedure for the diagnosis of LTA, but it is expensive and not readily available. Culture and smearing are practical, but they lack sensitivity. OBJECTIVE: The objective of this work is to compare the latter two methods in order to achieve a higher sensitivity at a lower cost. METHOD: Three culture media were compared in the process of isolating leishmaniasis: blood Agar Difco + Schneider + 20% fetal calf serum; Difco + Schneider + human sterile urine (2%); Schneider with sterile human urine (2%). Moreover, two techniques were compared for the demonstration of amastigotes: biopsy performed with smears, or matchstick scrapping RESULTS: The positivity and contamination indices (29-to-33% and 8-to-11%, respectively, p>0.05) were similar when comparing the cultures. The smears carried out by biopsy or the matchstick scrapping procedure had no significant differences (14 and 19%, respectively, p>0.05). Leishmania (Viannia) braziliensis predominated. CONCLUSION: In Brazil, urine may substitute fetal calf serum. The cost-to-benefit ratio is advantageous. Urine has no cost, while the market value of 500 ml of fetal calf serum is $US 185

Comparative biology and feeding behavior of Rhodnius neglectus and Rhodnius robustus (Triatominae) under laboratory conditions

Introdução: A competência vetorial de triatomíneos é determinada a partir de estudos sobre biologia e comportamento alimentar em condições de campo e/ou laboratório. Fatores como número de picadas, quantidade de sangue ingerido e tempo de defecação têm implicações na transmissão de tripanosomatídeos. Parâmetros biológicos e comportamentais de Rhodnius neglectus e R. robustus foram comparados experimentalmente para estimar diferenças no potencial de transmissão de tripanosomatídeos. Métodos: Os triatomíneos foram observados diariamente para determinar o período de desenvolvimento ninfal, mortalidade, detecção da fonte alimentar, número de picadas, tempo do repasto sanguíneo, quantidade de sangue ingerido, tempo entre o final do repasto e a primeira defecação e frequência de defecação. Resultados: Apesar do período ninfal de R. neglectus (156,4 ± 25,05d) ter sido menor que o de R. robustus (204,7 ± 13,22d), a mortalidade foi similar entre as espécies (63,8 e 65%, respectivamente). R. robustus e R. neglectus detectaram rapidamente a fonte alimentar, especialmente no primeiro estádio (2,5 e 1,6 min, respectivamente). Apesar do tempo de repasto sanguíneo ter sido similar entre as espécies, R. robustus ingeriu em média uma maior quantidade de sangue em todos os estádios, com maiores valores para as ninfas V. As ninfas de R. neglectus picaram mais vezes as fontes alimentares, defecaram mais rápido e mais frequentemente que as de R. robustus. Conclusões: Sob as condições de laboratório usadas, R. neglectus possui um maior potencial para transmissão de Trypanosoma cruzi e T. rangeli que R. robustus, atributo que deve ser avaliado em infecções experimentais.Introduction: The vector competence of triatomine insects is determined by studying their biology and feeding behavior under field and/or laboratory conditions. Factors including the number of bites, the amount of blood ingested and defecation time have implications for trypanosome transmission. The biological and behavioral parameters of Rhodnius neglectus and R. robustus were compared under experimental conditions to estimate differences in the potential transmission of trypanosomes. Methods: The insects were observed daily to determine the period of nymphal development, mortality, detection of food source, number of bites, time of blood meal intake, amount of blood ingested, time elapsed between the end of the meal and the first defecation and the frequency of defecation. Results: Although the nymphal development of R. neglectus (156.4 ± 25.05d) was lower than that of R. robustus (204.7 ± 13.22d), the mortality between species was similar (63.8 and 65% respectively). R. robustus and R. neglectus quickly located the food source, especially in the first instar (2.5 and 1.6 min, respectively). Although the time of blood meal intake was similar between the species, R. robustus ingested a larger amount of blood on average at all stages and exhibited higher values for the fifth instar. Nymphs of R. neglectus bit more frequently, and they defecated faster and more often than those of R. robustus. Conclusions: Under laboratory conditions,R. neglectus has a greater potential for transmission of Trypanosoma cruzi and T. rangeli than does R. robustus, an attribute that should be further evaluated in experimental infections

Sensibilidad de diferentes especies de Rhodnius (Hemiptera, Reduviidae, Triatominae) a una cepa brasileña de Trypanosoma rangeli (SC58/KP1-)

Introducción. Se han detectado asociaciones biológicas huésped-parásito específicas que sugieren que los triatominos del género Rhodnius podrían actuar como filtros biológicos en la transmisión de Trypanosoma rangeli. Objetivo. Estudiar la sensibilidad de cuatro especies de Rhodnius ( Rhodnius robustus , Rhodnius neglectus , Rhodnius nasutus y Rhodnius p ictipes ) frente a la cepa de T. rangeli (SC-58/KP1-). Materiales y métodos. Se seleccionaron treinta ninfas de cada especie después de xenodiagnóstico artificial en sangre infectada con T. rangeli. Se examinaron periódicamente m uestras de heces y hemolinfa. Los insectos con hemolinfas infectadas fueron alimentados en ratones a fin de comprobar la transmisión por picadura y posteriormente disecados para confirmar la infección de las glándulas salivales. Resultados . En Rhodnius pictipes se encontró un mayor porcentaje de infección intestinal que en las otras especies . Se detectaron epimastigotes y tripomastigotes en la hemolinfa de las cuatro especies , y se encontró que el parasitismo fue menor en las especies del linaje R. robustus . Rhodnius robustus y R. neglectus no transmitían T.rangeli a ratones por picadura: después de la disección , sus glándulas no estaban infectadas. Solo un espécimen de R.nasutus y dos de R. pictipes transmitieron el parásito por la picadura . La tasa de infección glandular fue de 16 % paraR. pictipes y de 4 % para R. nasutus. Conclusiones. La capacidad infecciosa ( hemolinfática, intestinal y glandular ) y la transmisión de T. rangeli (SC-58/KP1-) fueron mayores y más eficientes en R. pictipes . Estos resultados refuerzan la hipótesis de que estos triatominos actúan como filtros biológicos en la transmisión de T. rangeli. _______________________________________________________________________________________ ABSTRACTIntroduction: Specific host-parasite a ssociations have been detected experimentally and suggest that triatomines of the genus Rhodnius act as biological filters in the transmission of Trypanosoma rangeli. Objective: To analyze the susceptibility of four Rhodnius species ( Rhodnius robustus , Rhodnius neglectus , Rhodnius nasutus and Rhodnius pictipes ) to a Brazilian strain of T. rangeli (SC-58/KP1-). Materials and methods: We selected t hirty nymphs of each species, which were fed on blood infected with T. rangeli. Periodically, samples of feces and hemolymph were analyzed. Triatomines with T. rangeli in their hemolymph were fed on mice to check for transmission by bites. Later, the triatomines were dissected to confirm salivary gland infection. Results: Specimens of R. pictipes showed higher rates of intestinal infection compared to the other three species. Epimastigotes and trypomastigotes were detected in hemolymph of four species; however, parasitism was lower in the species of the R. robustus lineage. Rhodnius robustus and R. neglectus specimens did not transmit T. rangeli by bite; after dissection, their glands were not infected. Only one specimen of R. nasutus and two of R. pictipes transmitted the parasite by bite. The rate of salivary gland infection was 16% for R. pictipes and 4% for R. nasutus. Conclusions: Both infectivity (intestinal, hemolymphatic and glandular) and transmission of T. rangeli (SC58/KP1-) were greater and more efficient in R. pictipes. These results reinforce the hypothesis that these triatomines may act as biological filters in the transmission of T. rangeli. Key words: Trypanosoma rangeli, Rhodnius, host-parasite interactions