El presente trabajo describe la distribución geográfica actual de las principales especies de caracoles de agua dulce incriminadas como hospedadoras intermediarias de Schistosoma mansoni (4 especies de Biomphalaria), Fasciola hepatica (4 especies de Galba y Pseudosuccinea columella) y Paragonimus sp. (Aroapyrgus vivens) en Venezuela. Adicionalmente, se discute el status epidemiológico así como el hábitat de ocurrencia de cada una de estas especies, a fin de brindar información base para la vigilancia, manejo y control de los hospedadores intermediarios que participan en los ciclos vitales de los agentes causales de la esquistosomiasis, fascioliasis y paragonimiasis, que constituyen enfermedades desatendidas actualmente en Venezuela.

This study describes the current distribution patterns of the main species of freshwater mollusks incriminated as intermediate hosts of Schistosoma mansoni (Biomphalaria, 4 species), Fasciola hepatica (Galba, 4 species and Pseudosuccinea columella), and Paragonimus sp. (Aroapyrgus vivens) in Venezuela. Additionally, the epidemiological status and the main aquatic habitats of each species are discussed in order to bring basic information to help the surveillance and control of these neglected tropical diseases in 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.

Orally transmitted Chagas disease has become a matter of concern due to outbreaks reported in four Latin American countries. Although several mechanisms for orally transmitted Chagas disease transmission have been proposed, food and beverages contaminated with whole infected triatomines or their faeces, which contain metacyclic trypomastigotes of Trypanosoma cruzi, seems to be the primary vehicle. In 2007, the first recognised outbreak of orally transmitted Chagas disease occurred in Venezuela and largest recorded outbreak at that time. Since then, 10 outbreaks (four in Caracas) with 249 cases (73.5% children) and 4% mortality have occurred. The absence of contact with the vector and of traditional cutaneous and Romana’s signs, together with a florid spectrum of clinical manifestations during the acute phase, confuse the diagnosis of orally transmitted Chagas disease with other infectious diseases. The simultaneous detection of IgG and IgM by ELISA and the search for parasites in all individuals at risk have been valuable diagnostic tools for detecting acute cases. Follow-up studies regarding the microepidemics primarily affecting children has resulted in 70% infection persistence six years after anti-parasitic treatment. Panstrongylus geniculatushas been the incriminating vector in most cases. As a food-borne disease, this entity requires epidemiological, clinical, diagnostic and therapeutic approaches that differ from those approaches used for traditional direct or cutaneous vector transmission.

Orally transmitted Chagas disease (ChD), which is a well-known entity in the Brazilian Amazon Region, was first documented in Venezuela in December 2007, when 103 people attending an urban public school in Caracas became infected by ingesting juice that was contaminated with Trypanosoma cruzi. The infection occurred 45-50 days prior to the initiation of the sampling performed in the current study. Parasitological methods were used to diagnose the first nine symptomatic patients; T. cruzi was found in all of them. However, because this outbreak was managed as a sudden emergency during Christmas time, we needed to rapidly evaluate 1,000 people at risk, so we decided to use conventional serology to detect specific IgM and IgG antibodies via ELISA as well as indirect haemagglutination, which produced positive test results for 9.1%, 11.9% and 9.9% of the individuals tested, respectively. In other more restricted patient groups, polymerase chain reaction (PCR) provided more sensitive results (80.4%) than blood cultures (16.2%) and animal inoculations (11.6%). Although the classical diagnosis of acute ChD is mainly based on parasitological findings, highly sensitive and specific serological techniques can provide rapid results during large and severe outbreaks, as described herein. The use of these serological techniques allows prompt treatment of all individuals suspected of being infected, resulting in reduced rates of morbidity and mortality.

Se planteó identificar antígenos que pudieran ser reconocidos por los anticuerpos IgG1 e IgG3, descritos como protectores en la infección malárica, en personas con respuesta clínica adecuada (RCA) o falla al tratamiento (FT) antimalárico, provenientes de localidades con diferentes grados de endemicidad. Se evaluaron por Immunoblotting muestras de sueros de individuos provenientes de tres localidades del Edo. Amazonas (Venezuela): Puerto Ayacucho (Atures), San Juan de Manapiare (Manapiare) y Platanal (Alto Orinoco). La reactividad de IgG, IgG1 e IgG3 frente a componentes antigénicos del extracto de P. falciparum (FCB2), permitió identificar un mayor número de moléculas específicas en los pacientes con RCA que en los pacientes con FT. La frecuencia de reconocimiento de polipéptidos fue baja en las tres localidades, algunas moléculas con una frecuencia de reconocimiento igual o mayor al 20% pertenecían a sueros de individuos de las localidades de Puerto Ayacucho y Platanal, ambas con exposición permanente a P. falciparum. Dado el reconocimiento de polipéptidos por IgG, IgG1 e IgG3 en sueros de pacientes con RCA, estos podrían ser considerados como posibles blancos relevantes de la respuesta inmunológica protectora que coadyuven con el tratamiento antimalárico. Esto contribuiría al desarrollo y diseño de vacunas más efectivas, que prevengan la infección malárica y/o potencien la eficacia a la quimioterapia.

Here we studied the presence of antigens recognized by IgG1 and IgG3 antibodies, thought as protective, in patients with adequate clinical response (RCA) or treatment failure (FT), living in areas of different degrees of endemicity. Immunoblotting was evaluated from serum samples of individuals from three locations in the State Amazonas (Venezuela): Puerto Ayacucho (Atures), San Juan de Manapiare (Manapiare) and Pantanal (Alto Orinoco). The reactivity of IgG, IgG1 and IgG3 against antigenic components of the extract of P. falciparum (FCB2) identified a greater number of specific molecules in patients with RCA in patients with AFT. The frequency of recognition of polypeptides was low in all three locations, with some molecules having a recognition rate of greater than or equal to 20% sera of individuals belonging to the towns of Puerto Ayacucho and Platanal, both with cases of P. falciparum. Given the recognition of polypeptides by IgG, IgG1 and IgG3 in sera of patients with RCA, they could be considered as possible targets for relevant protective immune responses that contribute to malaria treatment. This would contribute to the development and design of more effective vaccines that prevent malaria infection and/or enhance the efficacy of chemotherapy.

Es esencial comprender la forma como las larvas de Schistosoma mansoni invaden y los mecanismos de evasión inmune utilizados por larvas y adultos, para el desarrollo racional de vacunas o drogas para prevenir o curar la esquistosomiasis. Este parásito tiene una organización molecular muy compleja en todos sus estadíos, por lo que la identificación de las proteínas más importantes es clave para investigar el metabolismo del esquistosoma y la interacción del parásito con el sistema inmune del hospedero. El objetivo de este trabajo fue evaluar el repertorio proteico del parásito utilizando una aproximación proteómica y la caracterización de extractos proteicos de dos estadios parasitarios diferentes de un aislado venezolano, como la cercaria y el verme adulto, previamente realizado por otros autores en otras aislados. Se realizó una comparación entre autores. Además, se identificaron diferentes isoformas de uno de los candidatos a vacuna, la glutation S transferasa (Sm28GST) por 2D SDS-PAGE y espectrometría de masas y se logró su detección inmunológica, usando sueros de conejos inmunizados con péptidos sintéticos derivados de la proteína Sm28GST. Estas técnicas permitieron identificar algunas de las moléculas blanco de la respuesta inmune protectora que están siendo evaluados como miembros potenciales de una vacuna multi-estadio y multi-componente y aclarar si los péptidos seleccionados indujeron anticuerpos capaces de reconocer diferentes isoformas de la Sm28GST

Understanding the mode of Schistosoma mansoni larval invasion and the mechanism of immune evasion utilized by larvae and adult worms is essential for a rational development of vaccines or drugs to prevent or cure the disease. This parasite has a very complex molecular organization in all parasite stages, and identifying the major parasite proteins would give clues to schistosome metabolism and to the interaction of the parasite with the host immune system. Our goal was the evaluation of the protein parasite repertoire using a proteomic approach, and the characterization of protein extracts from two different parasite stages of a Venezuelan isolate, such as cercariae and adult worms, previously performed by other authors in some other strains. A comparison among authors was made. Besides, we aimed to identify different isoforms of one of the vaccine candidates, the gluthation-S-transferase protein (Sm28GST), by 2D SDS-PAGE and mass spectrometry, and to achieve its immunologic detection using sera from rabbits immunized with synthetic peptides derived from the Sm28GST protein. These techniques allowed the identification of some of the target molecules of the protective immune response that are being evaluated as potential members of a multi-component and multi-stage anti-S. mansoni vaccine and to clarify if the selected peptides induce antibodies that are able to recognize different isoforms of the Sm28GST

Paragonimus are trematodes that normally live in the lungs of carnivorous and omnivorous mammals such as humans. An outbreak of Paragonimus sp. in which Didelphis marsupialis was the only wild reservoir incriminated was described in eastern Venezuela. In order to have immunological tools to detect the presence of Paragonimus sp. in this reservoir, a whole antigen of the adult worm of this parasite was elaborated. Didelphis marsupialis were captured in the locality of Aguas Blancas, Montes municipality, Sucre state, Venezuela, from which blood samples were obtained and a search for worms was performed in lungs. Worms were homogenized and ultracentrifugated to obtain FSPA to perform immunoassay (ELISA) to detect antibodies in opossums. The electrophoresis analysis showed a pattern of 22 molecules between 6 and 82 kDa; by western blot, the antigenic recognition of 8 antigenic molecules appeared,112 kDa and 268 kDa molecules being the most strongly recognized by positive sera. The negative sera did not recognize any band. The production of IgY in chicken enabled the development of reagents capable of performing a standard immunodiagnosis technique to find specific anti-Paragonimus sp. in Didelphis marsupialis in order to establish epidemiological surveillance of these reservoirs in endemic areas.

Los Paragonimus son trematodos que habitualmente viven en los pulmones de mamíferos carnívoros y omnívoros, entre ellos el hombre. En el oriente venezolano se encuentra el único foco de Paragonimus sp. donde Didelphis marsupialis es el único reservorio demostrado hasta ahora. Con el fin de tener herramientas de inmunodiagnóstico que detecten la presencia de Paragonimus sp. en esta especie, se elaboraron varios reactivos para realizar un ensayo inmunoenzimático ELISA. Entre ellos se obtuvo un antígeno crudo soluble de vermes adultos de Paragonimus y una inmunoglobulina de gallina anti-IgG de Didelphis marsupialis. Los mismos se capturaron en la localidad de Aguas Blancas, municipio Montes, estado Sucre, Venezuela, y se obtuvieron muestras sanguíneas; en el caso de estar infectados, los vermes adultos se extrajeron del pulmón. Los parásitos se homogenizaron y ultracentrifugaron para obtener la fracción soluble del parásito (FSPA) como antígeno para el ELISA y Western blot y detectar los anticuerpos en los Didelphis marsupialis. El análisis electroforético mostró 22 moléculas entre 6 y 82 kDa; por Western blot se presentó un reconocimiento antigénico de 8 moléculas siendo las de 112 kDa y 268 kDa las más reconocidas por los sueros positivos. Los sueros negativos no reconocieron ninguna proteína. La producción de IgY en gallinas permitió desarrollar las técnicas de inmunodiagnóstico para la búsqueda de anticuerpos específicos anti-Paragonimus sp. en Didelphis, cuya aplicación permitirá establecer la vigilancia epidemiológica de estos reservorios en áreas endémicas sin sacrificio de los mismos.

Se describe el proceso de investigación clínico-epidemiológica y de laboratorio que permitió establecer el nexo entre un caso de Enfermedad de Chagas en fase aguda aislado y una comunidad escolar urbana, así como la estrategia de diagnóstico y tratamiento de una emergencia médica para evitar mayor severidad clínica y mortalidad.

The clinical, laboratory and epidemiological investigations that established the connection between the index case of an acute episode of Chagas disease and an orally acquired outbreak in an urban school in Caracas are described. The strategy used for early diagnosis and treatment of this medical emergency prevented major clinical severity and mortality.

Paragonimus sp. es un trematodo que causa inflamación crónica del pulmón en mamíferos carnívoros y en el hombre, constituyendo un problema de salud pública en países asiáticos y latinoamericanos. Los trematodos poseen enzimas que facilitan la penetración y migración en diferentes hospederos a fin de garantizar su ciclo evolutivo. Con el objetivo de evaluar la diversidad enzimática de la fracción soluble (FSPA, 100.000 g) de un aislado venezolano de adultos de Paragonimus sp. se realizaron determinaciones enzimáticas a diferentes pH, usando curvas de calibración (A 405 nm vs. nmol) para interpolar la absorbancia de grupos p-nitrofenol o p-nitroanilina liberados por la hidrólisis de sustratos sintéticos; se utilizaron también sustratos 2-naftilamídicos y 2-naftólicos para determinar esterasas, peptidasas, fosfomonoesterasas y glicosidasas. Se demostró que fosfohidrolasas, glicosidasas y peptidasas están presentes en la FSPA, destacándose la β-NAG (0,55 μmol/h/mg, pH 5,5) y la cistein proteasa (0,4 μmol/h/mg, pH 5,5) como las actividades más elevadas, señalando la importancia funcional de la actividad glicosídica y peptídica en este parásito, las cuales están probablemente relacionadas con su hábitat y su necesidad de degradación de secreciones pulmonares. Estos resultados representan los primeros estudios enzimáticos registrados en vermes adultos de un aislado venezolano de Paragonimus sp. obtenidos del reservorio Didelphis marsupialis.

Paragonimus sp. is a trematode that causes chronic inflammation of the lung in carnivorous mammals and humans, which constitute a public health problem in Asian and Latin American countries. Trematodes have enzymes that facilitate their penetration and migration through different host organs to ensure their life cycle. To evaluate the enzymatic diversity of the soluble fraction (FSPA, 100,000 g) of a Venezuelan isolate of Paragonimus sp. adult worms, several enzyme determinations were conducted at different pH. The activities of enzymes releasing p-nitrophenol or p-nitroanilina from the corresponding dye-related synthetic peptides were assessed by interpolating absorbance (A 405 nm) values in the corresponding calibration curve (A 405 nm vs. nmol); on the other hand, absorbances of 2-naphtylamine and 2-naphtols released from another series of synthetic substrates were read at different wavelengths between 450 nm and 620 nm to assess for the activity of the corresponding hydrolases. Phosphohydrolase, glycosidase and peptidase activities were detected in FSPA, β-N-acetyl-β-D-glucosaminidase (0.55 μmol/h/mg, pH 5.5) and cystein protease (0.4 μmol/h/mg, pH 5.5) being higher than all the other detected activities. These activities are probably related to the adult worm habitat and its need for glycan and peptide degradation of lung secretions. These results represent the first enzymatic study done with a Venezuelan isolate of adult Paragonimus sp. worms collected from the common reservoir Didelphis marsupialis.

Se evaluó el test rápido OptiMAL® comparándolo con el examen convencional de observación de muestras sanguíneas para la detección de la malaria en dos grupos de individuos procedentes de diferentes áreas endémicas de Venezuela. Uno de los grupos (n = 113) con síntomas sugestivos de malaria, y otro representado por individuos asintomáticos (n = 89). El examen microscópico de las muestras de sangre de estas poblaciones determinó que 67,5% estaban infectados con P.vivax, 31,3% con P. falciparum y 1,2% con infecciones mixtas. La prueba OptiMAL® mostró 96,4% de sensibilidad, 100% de especificidad, con valor predictivo positivo de 100% y valor predictivo negativo de 97,5%. La detección de cualquier infección malárica en la población total presentó una concordancia óptima (kappa = 0,97). Sin embargo, estos parámetros fueron más bajos cuando la parasitemia era £ 300 parásitos/µL. El congelamiento de las muestras no afectó la sensibilidad y especificidad de la prueba. Nosotros concluimos que esta prueba rápida de malaria es sensible y especifica para el diagnóstico rápido de la malaria en el campo y puede complementar a la microcopia convencional.

We evaluated the OptiMAL® rapid dipstick test by comparing it with the conventional standard thick-blood film method, for the detection of malaria in two groups of individuals from different Venezuelan endemic areas. One of the groups consisted of individuals with malaria-like symptoms (n = 113) and the other of asymptomatic individuals (n = 89). The classical microscopy analysis of these populations determined that 67.5% were infected with P. vivax, 31.3% with P. falciparum, and 1.2% with mixed infections. The OptiMAL® test showed 96.4% sensitivity, 100% specificity, 100% positive predictive value, 97.5% negative predictive value and optimal concordance (kappa = 0.97), capable of detecting any malaria infection in the evaluated population. However, these parameters were lower when the parasitaemia was £ 300 parasites/µL. Freezing of the samples did not affect the sensitivity and specificity of the test. We concluded that this rapid malaria test is sensitive and specific for rapid diagnosis of malaria in the field and it is a complement to conventional microscopy.

Se evaluó la prueba Now® malaria ICT P.f/P.v. en personas con síntomas de malaria provenientes de dos áreas endémicas de Venezuela: estado Sucre en la región noreste costera (n=71) y el estado Amazonas en el sur (n=86). 102 muestras resultaron positivas (73 P. vivax, 25 P. falciparum, 2 P. malariae y 2 infecciones mixtas), 55 muestras resultaron negativas mediante el examen microscópico. La sensibilidad, especificidad, VPP y VPN del Now® malaria ICT P.f/P.v. para el diagnóstico de malaria fue 81,4%, 100%, 100% y 74,3%, respectivamente y un Kappa de 0,75. En Sucre la sensibilidad fue de 96,3%, especificidad 100%, VPP 100%, VPN 89,5% y Kappa 0,93 para P. vivax. En Amazonas, la sensibilidad fue 81%, especificidad y VPP 100%, VPN 90,5% y Kappa 0,85 para infecciones activas por P. vivax y P. malariae. Esta sensibilidad para P. vivax aumenta con parasitemias entre 101-500 par/μL. Para P. falciparum la sensibilidad fue 51,9%, especificidad de 100%, VPP de 100%, VPN de 74,5% y un Kappa de 0,56. La sensibilidad del método es de 100% para densidades mayores a 500 par/μL. La concordancia encontrada en este estudio entre la prueba Now® malaria ICT P.f/P.v. y el método parasitológico para las especies P. vivax / P. malariae, aunque no para P. falciparum, aporta un valor adicional a las ya conocidas características de la prueba tales como procedimiento fácil, rapidez e interpretación de los resultados en áreas de difícil acceso, por lo que concluimos que es una herramienta alternativa para el diagnóstico de malaria, sin llegar a sustituir el método parasitológico convencional.

We evaluated the Now® malaria ICT P.f/ P.v. test in symptomatic malaria patients from two different endemic areas of Venezuela: Sucre state in the northeastern costal region (n=71) and the Amazonas state in the south (n=86). One hundred two patients were positive by thick and thin blood smears, 73 with Plasmodium vivax , 25 with P. falciparum , 2 with P. malariae and 2 with mixed infections. Some 55 blood samples were negative. The sensitivity, specificity, PPV, NPV of the Now® malaria ICT P.f/P.v. test, were 81.4%, 100%, 100% and 74.3%, respectively and a Kappa of 0.75. With blood samples from Sucre state, the sensitivity was 96.3%, the specificity 100%, the PPV 100%, NPV 89.5% and a Kappa of 0.93 for P. vivax. In Amazonas State, the sensitivity was 81%, the specificity and PPV 100%, the NPV 90.5% and a Kappa of 0.85 for P. vivax and P. malariae. This sensitivity increased for P. vivax when parasitaemias were above 101 parasites/uL. For P. falciparum , the sensitivity was 51.9%, the specificity 100%, the PPV 100%, NPV was 74.5% and a Kappa of 0.56. The sensitivity was 100%, with more than 500 parasites/mL for this species. The high concordance found in this test with the thick and thin blood smear for all malaria species except P. falciparum gives an additional value to this dipstick, along with other well known characteristics such as the rapid and easy handling and interpretation in areas of difficult access. We concluded that the immunochromatographic test is a valuable additional diagnostic tool for malaria but not a substitute of the classical thin and thick blood smear.

O ultra-som abdominal pode ser uma ferramenta útil para o diagnóstico da fibrose periportal relacionada à infecção por Schistosoma mansoni, e também para planejar e monitorar a evolução da morbidade hepática após medidas de controle. Nós avaliamos a metodologia padronizada no ultra-som, proposta pela Organização Mundial da Saúde, para a detecção da fibrose periportal e hipertensão porta, em pacientes de área endêmica da Venezuela e o impacto do tratamento com praziquantel 3-5 anos depois. Após quimioterapia, houve reversão completa das lesões periportais em 28,2% dos casos e progressão da patologia em 5,1%. A melhora da patologia hepática começou com a redução do espessamento periportal seguida pela diminuição do tamanho do lobo esquerdo, baço e veias mesentérica e esplênica. O ultra-som confirma os achados clínicos após quimioterapia em pacientes com reversão da patologia; contudo, naqueles com patologia mais avançada, estes achados foram contraditórios. Não houve correlação entre evolução da patologia ultra-sonográfica com idade, intensidade da infecção ou achados sorológicos.

Abdominal ultrasound can be a useful tool for diagnosing periportal fibrosis related to Schistosoma mansoni infection, and also for planning and monitoring the evolution of hepatic morbidity following control measures. We evaluated the standardized ultrasound methodology proposed by the World Health Organization for detecting periportal fibrosis and portal hypertension, among patients from an endemic area in Venezuela, and the impact of praziquantel treatment 3-5 years later. After chemotherapy, complete reversal of periportal lesions was observed in 28.2% of the cases and progression of the disease in 5.1%. Improvement in the hepatic disease started with a reduction in the periportal thickening followed by a decrease in the size of the left hepatic lobe, spleen and mesenteric and spleen veins. Ultrasound confirmed the clinical findings after chemotherapy among the patients with reversal of the disease. However, in patients with more advanced disease, these findings were contradictory. There was no correlation between evolution of the disease seen on ultrasound and age, intensity of infection or serological findings.

De los 9 casos de fascioliasis humana registrados en Venezuela, 4 han sido publicados en los últimos 10 años, siendo 2 de éstos procedentes de la región andina. El riesgo de endemicidad frecuente en bovinos y la condición clínica de una niña de 14 años, con malestar abdominal, vómitos, eosinofilia y antecedentes de ingestión abundante de berros, motivó realizar un estudio en su lugar de procedencia (Timotes, Edo. Mérida), para conocer la exposición de la comunidad al riesgo de infección. Se evaluaron 65 personas, a quienes se les realizó historia clínica, con consentimiento previa información, toma de muestras de sangre, exámenes de heces (n=37) y ecografía abdominal (n=33). Se practicó ELISA con extracto soluble de adultos de Fasciola hepatica (ELISA-AFhES), resultando 9 personas positivas. Se practicó "Western blot" (WB) a todos los sueros positivos en ELISA, de los cuales 5 reconocieron moléculas específicas de 9, 14, 27 y 65 kDa, lo que constituye un patrón de positividad al WB. Los cuatro sueros restantes, con débil reactividad al ELISA, no reconocieron estas moléculas. Por estudios coprológicos se encontraron Entamoeba coli, Entamoeba histolytica/dispar, Blastocystis hominis, Giardia lamblia, Endolimax nana y Ascaris lumbricoides. Tres de las 5 personas positivas por ELISA-AFhES y WB-AFhES resultaron con huevos de Fasciola hepatica en las heces. Los 5 casos positivos corresponden a niñas de una familia, todas hermanas, cuyos padres resultaron sin infección, a pesar de que todos ingieren berros y ensaladas con productos de la región. El presente estudio constituye el primer reporte de transmisión a humanos en una población de un área bien delimitada en la región andina venezolana.

Of the 9 cases of human fascioliasis recorded in Venezuela, 4 have been published in the last 10 years, 2 of them originating from Andean region. The well known transmission of fascioliasis in cattle and the clinical condition of a 14-year-old girl with abdominal discomfort, vomiting, eosinophilia and previous abundant ingestion of watercress, motivated the field study in the site of occurrence (Timotes, Edo. Mérida in the Andean region) to learn the risk of community infection. Sixty-five people were evaluated clinically and serologically. Coprology was done in 37 and abdominal ultrasound in 33 persons. ELISA with adult Fasciola hepatica soluble extract (AFhES- ELISA) was performed with 9 persons being positive. Western blot (WB) was carried out on all ELISA positive sera, resulting in 5 that recognized 9, 14, 27 and 65 kDa specific molecules. The remaining four sera, with weak reactivity by ELISA, did not have this recognition pattern. By stool examination, we found Entamoeba coli, E. histolytica/dispar, Blastocystis hominis, Giardia lamblia, Endolimax nana and Ascaris lumbricoides. Three of the 5 positive people by AFhES-ELISA and AFhES-WB had F. hepatica eggs in their feces. The 5 positive cases are girls of a family, sisters and whose parents do not have the infection, although all consume watercress in salads with other vegetables from that region. The present study constitutes the first report of a well established focus of fascioliasis with human repercussion in Venezuela.

The presence of common antigens between Plasmodium falciparum and Anopheles albimanus was demonstrated. Different groups of rabbits were immunized with: crude extract from female An. albimanus (EAaF), red blood cells infected with Plasmodium falciparum (EPfs), and the SPf66 synthetic malaria vaccine. The rabbit's polyclonal antibodies were evaluated by ELISA, Multiple Antigen Blot Assay (MABA), and immunoblotting. All extracts were immunogenic in rabbits according to these three techniques, when they were evaluated against the homologous antigens. Ten molecules were identified in female mosquitoes and also in P. falciparum antigens by the autologous sera. The electrophoretic pattern by SDS-PAGE was different for the three antigens evaluated. Cross-reactions between An. albimanus and P. falciparum were found by ELISA, MABA, and immunoblotting. Anti-P. falciparum and anti-SPf66 antibodies recognized ten and five components in the EAaF crude extract, respectively. Likewise, immune sera against female An. albimanus identified four molecules in the P. falciparum extract antigen. As far as we know, this is the first work that demonstrates shared antigens between anophelines and malaria parasites. This finding could be useful for diagnosis, vaccines, and the study of physiology of the immune response to malaria.

Epítopes de antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus fueron identificados. Diferentes grupos de conejos fueron inmunizados con: extracto crudo de mosquito hembra de An. albimanus (EAaH), glóbulos rojos infectados con P. falciparum (EPfs) y la vacuna antimalárica sintética SPf66. Los anticuerpos policlonales producidos en conejos fueron evaluados por ELISA, inmunoensayo simultáneo de múltiples antígenos (MABA) e Immunoblotting. Todos los extractos resultaron inmunogénicos cuando se evaluaron por ELISA, MABA e Immunoblotting. Diez moléculas fueron identificadas en los mosquitos hembras y diez en los antígenos de P. falciparum por los sueros autólogos. El patrón electroforético por SDS-EGPA fue diferente para los tres antígenos evaluados. La reactividad cruzada de moléculas entre An. albimanus y P. falciparum fue demostrada por ELISA, MABA e Immunoblotting. Anticuerpos anti-P. falciparum y anti-SPf66 reconocieron diez y cinco componentes respectivamente en el extracto crudo de anofelinos (EAaH). Asimismo, sueros inmunes contra An. albimanus hembra identificaron cuatro moléculas en el extracto del antígeno de P. falciparum. Hasta el presente, este es el primer estudio en el que se demuestra la presencia de antígenos compartidos entre anofelinos y los parásitos de malaria. Este hallazgo podría ser de relevancia para el diagnóstico, vacunas e interpretación de la fisiopatología de la respuesta inmunitaria en malaria.

Control of schistosomiasis in Venezuela has been a topic of major interest and controversy among the metaxenic parasitosis. A small area of transmission of approximately 15,000 km2 was thought to be eradicated some years ago. However, some epidemiological characteristics of our transmission area have limited the success on the way toward eradication. Since 1945, when the Schistosomiasis Control Program started, the prevalence in the endemic area has decreased from 14% in 1943 to 1.4% in 1996. Until 1982, the surveillance of active cases was based on massive stool examination. Since then, the Schistosomiasis Research Group (SRG) recommended the additional use of serologic tests in the Control Program and the selective or massive chemotherapy depending on serological and parasitological prevalence of each community. At present, the real prevalence is underestimated due to the fact that approximately 80% of the individuals eliminate less than 100 eggs/g of feces. Those persons could be responsible for the maintenance of the foci going on and therefore limiting the impact of the control measures. Efforts of the SRG are being oriented toward improvement of immunodiagnostic tests by using defined antigens (enzymes) and chemically synthesized peptides, derived from relevant molecules of the parasite, either for antibodies or antigens search. On the other hand, introduction of snail competitors has been a biological weapon in the control of the intermediate host in certain areas. However, the recent reinfestation of water courses by Biomphalaria glabrata, the increased prevalence in some areas, together with important administrative changes at the Control Program of the Minister of Health, have arisen new questions and doubts, challenging the eradication strategy proposed during the last decade.