One Health initiative in the Bolivian Altiplano human fascioliasis hyperendemic area: Lymnaeid biology, population dynamics, microecology and climatic factor influences / Aplicação do conceito One Health na área hiperendêmica de fasciolíase humana do Altiplano Boliviano: biologia dos limneídeos, dinâmica populacional, microecologia e influência de fatores climáticos

Abstract Fascioliasis is a freshwater snail-borne zoonotic disease. The Northern Bolivian Altiplano is a very high altitude endemic area where the highest human prevalences and intensities have been reported. Preventive chemotherapy by treatment campaigns is yearly applied. However, liver fluke infection of cattle, sheep, pigs and donkeys assures endemicity and consequent human infection and re-infection risks. A One Health action has therefore been implemented. Activity concerns lymnaeid vectors and environment diversity. Studies included growth, egg-laying and life span in laboratory-reared lymnaeids. Different habitat types and influencing factors were assessed. All populations proved to belong to Galba truncatula by rDNA sequencing. Analyses comprised physico-chemical characteristics and monthly follow-up of water temperature, pH and quantity, and lymnaeid abundance and density. Population dynamics in the transmission foci differed. Mean environmental temperature was lower than fluke development minimum temperature threshold, but water temperature was higher, except during winter. A two generations/year pattern appeared in permanent water habitats, and one generation/year pattern in habitats drying out for months. The multidisciplinary control measures can be extended from one part of the endemic area to another. These studies, made for the first time at very high altitude, constitute a baseline useful for fascioliasis control in other countries.

Resumo A fasciolíase é uma doença zoonótica transmitida para os humanos por formas evolucionárias de Fasciola hepatica oriundas de limneídeos infectados. O Altiplano Boliviano Norte é uma área endêmica de altitude muito alta, onde foram relatadas as maiores prevalências e intensidades em infecções humanas. A quimioterapia preventiva por campanhas de tratamento é aplicada anualmente. No entanto, infecção por Fasciola hepatica em bovinos, ovelhas, suínos e asininos garante endemicidade e consequentes riscos de infecção e reinfecção humana. Portanto, ações norteadas no conceito "One Health" foram implementadas. As atividades envolveram os limneídeos e a avaliação da diversidade de ambientes. Os estudos incluíram o crescimento, postura de ovos e expectativa de vida de limneídeos criados em laboratório, bem como a avaliação da influência dos diferentes hábitats. Todas as populações foram identificadas como Galba truncatula por meio do sequenciamento de rDNA. As análises incluíram características físico-químicas e acompanhamento mensal da temperatura, pH, quantidade da água, abundância e densidade de limneídeos. A dinâmica populacional nos focos de transmissão diferiu. A temperatura ambiente média foi mais baixa do que o limite mínimo de temperatura do desenvolvimento do helminto, mas a temperatura da água foi mais alta, exceto durante o inverno. Um padrão de duas gerações/ano apareceu em hábitats com água permanente, enquanto um padrão de uma geração/ano foi observado em habitats que ficam secos durante meses. Os resultados permitem concluir que as medidas multidisciplinares de controle podem ser estendidas de uma parte da área endêmica para outra. Esses estudos, realizados pela primeira vez em altitudes muito elevadas, constituem uma base útil e extrapolável para o controle da fasciolíase.

Prevalence of asymptomatic Plasmodium vivax infections in the north-eastern focus of malaria of Venezuela / Prevalencia de infecciones asintomáticas por Plasmodium vivax en el foco malárico oriental de Venezuela

Malaria remains as a public health problem in Venezuela. In 2015 there were 136,402 cases reported by the Ministry of Popular Power for Health, being the parasite prevalence 73.95% for Plasmodium vivax, 17.6% for Plasmodium falciparum, 0.0095% for Plasmodium malariae and 8.42% mixed infections (P. vivax + P. falciparum). During the period 1999-2002 the number of cases in Venezuela ranged between 21,685 and 29,337, being the Sucre State with highest levels of malaria prevalence, with Plasmodium vivax as the unique specie in this region. In 2002 the Municipality of Cajigal had the highest Annual Parasite Incidence (API) of country, being 260 cases per 1000 inhabitants. In view of the difficulty in controlling malaria in this area, the prevalence of asymptomatic carriers was investigated as one of the epidemiological factors contributing to the persistence of malaria transmission. One hundred fifty people were included in the study, with no history of recent malaria infection, or any symptom and also, not having used antimalarial drugs during the 30 days prior to study entry. To do this, a malaria Rapid Diagnostic Test (mRDTs) was used for the determination of antigenemic (OptiMAL®) and PCR (polymerase chain reaction) in conjunction with the reference "Gold Standard", the conventional thick and thin blood smears (TTBS). It was found a prevalence of infection of 1.33% by mRDTs and TTBS and 8% by PCR which allowed the detection of 10 asymptomatic cases in addition, with a sensitivity and specificity of 100% and 93.4% respectively. The presence of asymptomatic carriers in this area reveals the difficulties that face the Malaria Control Program in the eventual elimination of this specific malaria foci. It is necessary reinforces the maintenance of the epidemiological surveillance using more sensitive diagnostic techniques, as well as to adapt the control measures based on the current findings.

La malaria sigue siendo un problema de salud pública en Venezuela. Para el año 2015 el Ministerio del Poder Popular para la Salud reportó 136.402 casos, siendo la fórmula parasitaria 73,95% para Plasmodium vivax, 17,6% para Plasmodium falciparum, 0,0095 para Plasmodium malariae y 8,42% para infecciones mixtas (P. vivax + P. falciparum). Durante el período 1999-2002, el número de casos en Venezuela estuvo entre 21.685 y 29.337, siendo el Estado Sucre el que mostró los niveles más altos de prevalencia de malaria, con P. vivax como única especie en la región. En el año 2002 el Municipio Cajigal registró el Índice Parasitario Anual (IPA) más alto del país, siendo 260 casos por 1000 habitantes. En vista de las dificultades para controlar la malaria en esta área, se investigó la prevalencia de portadores asintomáticos como uno de los factores contribuyentes en la persistencia de la transmisión malárica. Ciento cincuenta personas fueron incluidas en el estudio sin historia de infección reciente por malaria o ningún síntoma, así como no haber consumido drogas antimaláricas durante los 30 días anteriores de ingresar al estudio. Para ello, se usó la prueba rápida de diagnóstico para malaria (PRDxm) para la determinación de antígenemia (OptiMAL®) y la técnica de biología molecular basada en la Reacción en Cadena de la Polimerasa (PCR), conjuntamente con la "prueba oro," como método convencional, la Gota Gruesa y Extendido de Sangre (GGES). Se encontró una prevalencia de infección de 1,33% por GGES y por prueba rápida de diagnóstico OptiMAL® y 8% mediante PCR. La técnica de PCR permitió la detección adicional de 10 casos asintomáticos con una sensibilidad y especificidad del 100% y 93,4% respectivamente. La presencia de portadores asintomáticos en esta área revela las dificultades que enfrenta el Programa de Control de la Malaria en la eliminación eventual de esta parasitosis en este foco. Es necesario reforzar el mantenimiento de la vigilancia epidemiológica usando técnicas de diagnóstico más sensibles, así como adoptar medidas de control basadas en estos hallazgos.

A nuclear ribosomal DNA pseudogene in triatomines opens a new research field of fundamental and applied implications in Chagas disease

A pseudogene, designated as "ps(5.8S+ITS-2)", paralogous to the 5.8S gene and internal transcribed spacer (ITS)-2 of the nuclear ribosomal DNA (rDNA), has been recently found in many triatomine species distributed throughout North America, Central America and northern South America. Among characteristics used as criteria for pseudogene verification, secondary structures and free energy are highlighted, showing a lower fit between minimum free energy, partition function and centroid structures, although in given cases the fit only appeared to be slightly lower. The unique characteristics of "ps(5.8S+ITS-2)" as a processed or retrotransposed pseudogenic unit of the ghost type are reviewed, with emphasis on its potential functionality compared to the functionality of genes and spacers of the normal rDNA operon. Besides the technical problem of the risk for erroneous sequence results, the usefulness of "ps(5.8S+ITS-2)" for specimen classification, phylogenetic analyses and systematic/taxonomic studies should be highlighted, based on consistence and retention index values, which in pseudogenic sequence trees were higher than in functional sequence trees. Additionally, intraindividual, interpopulational and interspecific differences in pseudogene amount and the fact that it is a pseudogene in the nuclear rDNA suggests a potential relationships with fitness, behaviour and adaptability of triatomine vectors and consequently its potential utility in Chagas disease epidemiology and control.

DNA multigene sequencing of topotypic specimens of the fascioliasis vector Lymnaea diaphana and phylogenetic analysis of the genus Pectinidens (Gastropoda)

Freshwater lymnaeid snails are crucial in defining transmission and epidemiology of fascioliasis. In South America, human endemic areas are related to high altitudes in Andean regions. The species Lymnaea diaphana has, however, been involved in low altitude areas of Chile, Argentina and Peru where human infection also occurs. Complete nuclear ribosomal DNA 18S, internal transcribed spacer (ITS)-2 and ITS-1 and fragments of mitochondrial DNA 16S and cytochrome c oxidase (cox)1 genes of L. diaphana specimens from its type locality offered 1,848, 495, 520, 424 and 672 bp long sequences. Comparisons with New and Old World Galba/Fossaria, Palaearctic stagnicolines, Nearctic stagnicolines, Old World Radix and Pseudosuccinea allowed to conclude that (i) L. diaphana shows sequences very different from all other lymnaeids, (ii) each marker allows its differentiation, except cox1 amino acid sequence, and (iii) L. diaphana is not a fossarine lymnaeid, but rather an archaic relict form derived from the oldest North American stagnicoline ancestors. Phylogeny and large genetic distances support the genus Pectinidens as the first stagnicoline representative in the southern hemisphere, including colonization of extreme world regions, as most southern Patagonia, long time ago. The phylogenetic link of L. diaphana with the stagnicoline group may give light to the aforementioned peculiar low altitude epidemiological scenario of fascioliasis.

Genetic structure of Triatoma venosa (Hemiptera: Reduviidae): molecular and morphometric evidence

Triatoma venosa presents a restricted geographical distribution in America and is considered as a secondary vector of Chagas disease in Colombia and Ecuador. A total of 120 adult insects were collected in domestic and peridomestic habitats in an endemic area of the department of Boyacá, Colombia, in order to determine their genetic structure through morphometric and molecular techniques. The head and wings of each specimen were used for the analyses of size, shape, and sexual dimorphism. A significant sexual dimorphism was found, although no differences in size among the studied groups were detected. Differences were found in the analyzed structures except for male heads. DNA was extracted from the legs in order to carry out the internal transcriber space-2 (ITS-2) amplification and the randon amplified polymorphic DNA (RAPD) analyses. Length polymorphisms were not detected in the ITS-2. Fst and Nm values were estimated (0.047 and 3.4, respectively). The high genetic flow found among the insects captured in the domicile and peridomiciliary environment does not permit a genetic differentiation, thus establishing the peridomicile as an important place for epidemiological surveillance.