Lutzomyia longipalpis (Diptera: Psychodidae) Argentina-Bolivia border: new report and genetic diversity.

American visceral leishmaniasis (AVL) has two main scenarios of transmission as follows: scattered cases in rural areas and urban outbreaks. Urban AVL is in active dispersion from the northeastern border of Argentina-Paraguay-Brazil to the South. The presence of Lutzomyia longipalpis was initially reported in urban environments in the northwestern border of the country. The presence of Lu. longipalpis, environmental variables associated with its distribution, and its genetic diversity were assessed in Salvador Mazza, Argentina, on the border with Bolivia. The genetic analysis showed high haplotype diversity, low nucleotide diversity, and low nucleotide polymorphism index. We discuss the hypothesis of an expanding urban population with introgressive hybridisation of older haplogroups found in their path in natural forest or rural environments, acquiring a new adaptability to urban environments, and the possibility of changes in vector capacity.

Lutzomyia longipalpis (Diptera: Psychodidae) Argentina-Bolivia border: new report and genetic diversity

American visceral leishmaniasis (AVL) has two main scenarios of transmission as follows: scattered cases in rural areas and urban outbreaks. Urban AVL is in active dispersion from the northeastern border of Argentina-Paraguay-Brazil to the South. The presence of Lutzomyia longipalpis was initially reported in urban environments in the northwestern border of the country. The presence of Lu. longipalpis, environmental variables associated with its distribution, and its genetic diversity were assessed in Salvador Mazza, Argentina, on the border with Bolivia. The genetic analysis showed high haplotype diversity, low nucleotide diversity, and low nucleotide polymorphism index. We discuss the hypothesis of an expanding urban population with introgressive hybridisation of older haplogroups found in their path in natural forest or rural environments, acquiring a new adaptability to urban environments, and the possibility of changes in vector capacity.

Prevalencia de infección por Trypanosoma cruzi en escolares de Salta y Chaco, Argentina / Seroprevalencia of Trypanosoma cruzi infection in school-age children from localities in Salta and Chaco, Argentina / Prevalência de infecção por Trypanosoma cruzi em crianças em idade escolar de Salta e Chaco, na Argentina

El objetivo del trabajo consistió en identificar la seroprevalencia de la infección por Trypanosoma cruzi en niños en edad escolar en localidades de las provincias de Salta y Chaco. Se trabajó en 44 escuelas de la ciudad de Salta, en parajes de San Carlos; en 10 escuelas de La Unión y en 7 escuelas de Taco Pozo. El trabajo tiene un diseño de corte transversal. La toma de muestra se realizó por punción capilar con equipos Serokit, y la confirmación de los casos seropositivos o dudosos por punción venosa, y obtención de suero, para realizar HAI y ELISA. Los casos seropositivos confirmados fueron tratados con Benznidazol® durante 60 días en dosis de 5-7mg/kg/ día. Para el análisis estadístico se elaboraron tablas con frecuencias absolutas y relativas. Se analizaron 17.884 escolares y se detectaron159 seropositivos, siendo la mayor seroprevalencia en la localidad de La Unión y la menor en la ciudad de Salta. Se aplicó tratamiento a 93 niños (71,54 %) de la ciudad y en el ámbito rural se trataron todos los casos. La vía de infección vectorial fue la de mayor predominio en las madres (64,47%). Se concluye que aunque la seroprevalencia fue menor en la ciudad de Salta que en las zonas rurales, es necesario continuar con la vigilancia.

The aim of this work was to identify seroprevalence of Trypanosoma cruzi infection in school-age children who live in localities from Salta and Chaco. This work was conducted in the following schools: 44 located in Salta city, 10 in La Unión, 7 in Taco Pozo, and several in rural spots around San Carlos town. The design was cross-sectional and the samples were taken by capillary punction with Serokit equipment. Seropositive cases were confirmed by HAI and ELISA performed on serum obtained by venous punction. Confirmed seropositive cases were treated with Benznidazol® for 60 days in doses of 5-7 mg/kg/day. Tables with absolute and relative frequencies were made for statistical analysis. It resulted that the number of school-aged children analyzed was 17,884, 159 being seropositive. The highest seroprevalence was detected in La Unión and the lowest in Salta city. Treatment was given to 93 children (71.54%) from Salta city, while every child was treated in rural areas. Infections in mothers was vector-borne mainly (64.47%). It can be concluded that even though seroprevalence was lower in the city of Salta than in rural areas, it is important to continue monitoring for Chagas disease.

O objetivo do trabalho consistiu em identificar a soroprevalência da infecção por Trypanosoma cruzi em crianças em idade escolar em localidades das províncias de Salta e de Chaco. O trabalho foi realizado em 44 escolas da cidade de Salta, em paragens de San Carlos; em 10 escolas de La Unión e em 7 escolas de Taco Pozo. O mesmo tem um desenho de corte transversal. Tomada de amostra: foi realizada por punção capilar com equipamentos Serokit e a confirmação dos casos soropositivos ou duvidoso por punção venosa e obtenção de soro, para realizar HAI e ELISA. Os casos soropositivos confirmados foram tratados com Benznidazole® durante 60 dias em doses de 5-7 mg/kg/dia. Para a análise estatística foram preparadas tabelas com frequências absolutas e relativas. Analisaram-se 17.884 crianças detectando 159 soropositivos, sendo a maior soroprevalência na cidade de La Unión e a menor na cidade de Salta. Aplicou-se o tratamento a 93 crianças, (71,54%) da cidade e na área rural se trataram todos os casos. A via de infecção vetorial foi a de maior predominância nas mães (64,47%). Conclui-se que embora a soroprevalência tenha sido menor na cidade de Salta do que nas áreas rurais, é necessário continuar com a vigilância.

Mansonella ozzardi in Neotropical region of Argentina: Prevalence through time (1986-2010).

Human filariasis caused by Mansonella ozzardi is a parasitic infection of a controversial pathology and poorly studied in Argentina. The aim of this study was not only to obtain data of the prevalence of M. ozzardi in Northwestern Argentina through comparison of infection rates in relation to sex and age group determining the range of distribution of mansonelliasis in the region but also to investigate the prevalence of the cases over time. Through field work carried between 1986 and 2010 by technicians of the National Ministry of Health, aiming to detect active cases of malaria in the Northwestern Argentina, blood samples were taken for smear and thick blood. 417 blood samples were examined, 381 of them (91.4%) were positive for M. ozzardi. The highest prevalence was found in Salta province (92.3%) mainly affecting the male sex (92.6%) and the age groups comprised between 48-57 years (97.0%) and ≥ 68 (90.7%). The paired t-test and Spearman coefficients showed significant differences in prevalence according to sex (t=2.677; p=0.015), and according infection rates in males and females/age (r=0.994; p=0.001; r=0.994, p=0.001, respectively). The prevalence over time showed a general pattern with the highest cases in 1986, decreasing later during the following years. Aguas Blancas, El Oculto and San Ramón de la Nueva Orán, exhibited a pattern of prevalence according to the general trend but Salvador Mazza and Tartagal, which are also localities close to the border with Bolivia, showed peaks of cases up to 2010. These results provide relevant information about M. ozzardi in Argentina, demonstrating not only its presence and endemicity after almost 100 years from its discovery in the country, but also its wide range of distribution in the region.

Satellite-derived NDVI, LST, and climatic factors driving the distribution and abundance of Anopheles mosquitoes in a former malarious area in northwest Argentina.

Distribution and abundance of disease vectors are directly related to climatic conditions and environmental changes. Remote sensing data have been used for monitoring environmental conditions influencing spatial patterns of vector-borne diseases. The aim of this study was to analyze the effect of the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS), and climatic factors (temperature, humidity, wind velocity, and accumulated rainfall) on the distribution and abundance of Anopheles species in northwestern Argentina using Poisson regression analyses. Samples were collected from December, 2001 to December, 2005 at three localities, Aguas Blancas, El Oculto and San Ramón de la Nueva Orán. We collected 11,206 adult Anopheles species, with the major abundance observed at El Oculto (59.11%), followed by Aguas Blancas (22.10%) and San Ramón de la Nueva Orán (18.79%). Anopheles pseudopunctipennis was the most abundant species at El Oculto, Anopheles argyritarsis predominated in Aguas Blancas, and Anopheles strodei in San Ramón de la Nueva Orán. Samples were collected throughout the sampling period, with the highest peaks during the spring seasons. LST and mean temperature appear to be the most important variables determining the distribution patterns and major abundance of An. pseudopunctipennis and An. argyritarsis within malarious areas.

Weather Variability Associated with Aedes (Stegomyia) aegypti (Dengue Vector) Oviposition Dynamics in Northwestern Argentina.

This study aims to develop a forecasting model by assessing the weather variability associated with seasonal fluctuation of Aedes aegypti oviposition dynamic at a city level in Orán, in northwestern Argentina. Oviposition dynamics were assessed by weekly monitoring of 90 ovitraps in the urban area during 2005-2007. Correlations were performed between the number of eggs collected weekly and weather variables (rainfall, photoperiod, vapor pressure of water, temperature, and relative humidity) with and without time lags (1 to 6 weeks). A stepwise multiple linear regression analysis was performed with the set of meteorological variables from the first year of study with the variables in the time lags that best correlated with the oviposition. Model validation was conducted using the data from the second year of study (October 2006- 2007). Minimum temperature and rainfall were the most important variables. No eggs were found at temperatures below 10 °C. The most significant time lags were 3 weeks for minimum temperature and rains, 3 weeks for water vapor pressure, and 6 weeks for maximum temperature. Aedes aegypti could be expected in Orán three weeks after rains with adequate min temperatures. The best-fit forecasting model for the combined meteorological variables explained 70 % of the variance (adj. R(2)). The correlation between Ae. aegypti oviposition observed and estimated by the forecasting model resulted in rs = 0.80 (P < 0.05). The forecasting model developed would allow prediction of increases and decreases in the Ae. aegypti oviposition activity based on meteorological data for Orán city and, according to the meteorological variables, vector activity can be predicted three or four weeks in advance.

Demographic history and population structure of Anopheles pseudopunctipennis in Argentina based on the mitochondrial COI gene.

BACKGROUND: Anopheles pseudopunctipennis is an important malaria vector in the Neotropical region and the only species involved in Plasmodium transmission in the Andean foothills. Its wide geographical distribution in America, high preference for biting humans and capacity to rest inside dwellings after feeding, are attributes contributing to its vector status. Previous reports have tried to elucidate its taxonomic status, distinguishing populations from North, Central and South America. In the present study we used a mitochondrial marker to examine the demographic history of An. pseudopunctipennis in northwestern Argentina. METHODS: Twelve localities were selected across 550 km of the distribution of this species in Argentina, including two near the Bolivian border and several in South Tucumán, for sampling. A fragment of the cytochrome oxidase I (COI) gene was sequenced and haplotype relationships were analyzed by a statistical parsimony network and a Neighbor-Joining (NJ) tree. Genetic differentiation was estimated with FST. Historical demographic processes were evaluated using diversity measures, neutrality tests and mismatch distribution. RESULTS: Forty-one haplotypes were identified, of which haplotype A was the most common and widely distributed. Neither the network nor the NJ tree showed any geographic differentiation between northern and southern populations. Haplotype diversities, Tajima's DT and Fu & Li's F and D neutrality tests and mismatch distribution supported a scenario of Holocene demographic expansion. CONCLUSION: The demographic pattern suggests that An. pseudopunctipennis has undergone a single colonization process, and the ancestral haplotype is shared by specimens from all localities, indicating mitochondrial gene flow. Genetic differentiation was minimal, observed only between one northern and one southern locality. The estimated time of the population expansion of this species was during the Holocene. These data suggest that regional vector control measures would be equally effective in both northern and southern localities sampled, but also that insecticide resistant genes may spread rapidly within this region.

Diagnóstico de infección por Trypanosoma cruzi en Centros de Atención Primaria de Salta, Argentina / Diagnosis of Trypanosoma cruzi infection in Primary Public Health Centers of Salta, Argentina / Diagnóstico de infecþÒo por Trypanosoma cruzi nos Postos de Saúde de Salta, Argentina

La Enfermedad de Chagas causada por el parásito hemoflagelado Trypanosoma cruzi, constituye un grave problema de Salud Pública. En Argentina, se controla sistemáticamente la sangre a transfundir, la donación de órganos y se ha disminuido notablemente la transmisión vectorial. El objetivo de este proyecto fue implementar el uso del equipo para recolección de sangre capilar y conservación en glicerina (Serokit) en los servicios de enfermería de los Centros de Atención Primaria de la Salud en la ciudad de Salta a fin de conocer la seroprevalencia de infección por Trypanosoma cruzi en pacientes que concurren a los mismos. Para ello se realizó el par serológico HAI y ELISA en las muestras conservadas en Serokit y luego en muestras de sangre tomadas por punción venosa para confirmación. Durante dos años de trabajo se analizaron 1647 pacientes que concurrieron a 28 Centros de Salud, resultando 1,7% (29/1647) seropositivos. El Valor Predictivo Positivo fue 93,50% y el Valor Predictivo Negativo fue 99,8%. Todos los niños seropositivos fueron tratados con Benznidazol. Se concluye que el uso de Serokit para la toma y conservación de muestras para posterior diagnóstico de infección por Trypanosoma cruzi es recomendable en Centros de Atención Primaria de la Salud que no cuentan con laboratorio.(AU)

Chagas disease is caused by the hemoflagelate parasite Trypanosoma cruzi, and represents a main concern in public health. In Argentina, blood transfusion and organ donation are systematically controlled for T. cruzi infection, and vectorial transmission has dropped significantly. The aim of this project was to implement the use of the equipment for collecting capillary blood and conservation in glycerine (Serokit) in the nursery service of Primary Health Care Centers (PHCC) in the city of Salta, and to know the seroprevalence of T. cruzi infection in PHCC patients. To that aim, the serological pair HAI and ELISA was carried out in samples preserved in Serokit, followed by analysis of blood samples taken by venous punction to confirm the results. During a two-year period, 1647 patients that were assisted at 28 PCHC were analyzed, resulting in 1.7% (29/1647) seropositive samples. Positive Predictive Value was 93.5% and Negative Predictive Value was 99.8%. Every seropositive child was given Benznidazole treatment. It can be concluded that use of Serokit for taking and preserving samples to diagnose serologically T. cruzi infection is recommended in PHCC that lack their own biochemistry laboratory.(AU)

A doenþa de Chagas produzida pelo protozoário flagelado Trypanosoma cruzi constitui um grave problema para a Saúde Pública. Na Argentina, o controle sistemático do sangue para transfusÒo e o do órgÒo para transplantar, fez com que diminuísse notavelmente a transmissÒo vetorial. O objetivo deste projeto foi implementar o uso do equipamento para coleta de sangue capilar e conservaþÒo em glicerina (Serokit) nos serviþos de enfermagem dos Postos de AtenþÒo Primaria da Saúde da cidade de Salta a fim de conhecer a soroprevalÛncia de infecþÒo com Trypanosoma cruzi em pacientes que sÒo atendidos nos mesmos. Foi realizado o par sorológico HAI e ELISA nas amostras conservadas em Serokit e depois nas amostras de sangue retiradas através de uma punþÒo venosa para a confirmaþÒo. Durante dois anos de trabalho, foram analisados 1647 pacientes que foram atendidos nos 28 Postos de Saúde, resultando 1.7% (29/1647) soropositivos. O Valor Preditivo Positivo foi Tripae 93.50% e o Valor Preditivo Negativo foi de 99.8%. Todas as crianþas soropositivas foram medicadas com Benznidazol. A conclusÒo é que o uso de Serokit para a tomada e conservaþÒo de amostras para posterior diagnóstico de infecþÒo por Trypanosoma cruzi é recomendável nos Postos de AtenþÒo Primária da Saúde onde nÒo existe a disponibilidade de laboratórios.(AU)

Diagnóstico de infección por Trypanosoma cruzi en Centros de Atención Primaria de Salta, Argentina / Diagnosis of Trypanosoma cruzi infection in Primary Public Health Centers of Salta, Argentina / Diagnóstico de infecção por Trypanosoma cruzi nos Postos de Saúde de Salta, Argentina

La Enfermedad de Chagas causada por el parásito hemoflagelado Trypanosoma cruzi, constituye un grave problema de Salud Pública. En Argentina, se controla sistemáticamente la sangre a transfundir, la donación de órganos y se ha disminuido notablemente la transmisión vectorial. El objetivo de este proyecto fue implementar el uso del equipo para recolección de sangre capilar y conservación en glicerina (Serokit) en los servicios de enfermería de los Centros de Atención Primaria de la Salud en la ciudad de Salta a fin de conocer la seroprevalencia de infección por Trypanosoma cruzi en pacientes que concurren a los mismos. Para ello se realizó el par serológico HAI y ELISA en las muestras conservadas en Serokit y luego en muestras de sangre tomadas por punción venosa para confirmación. Durante dos años de trabajo se analizaron 1647 pacientes que concurrieron a 28 Centros de Salud, resultando 1,7% (29/1647) seropositivos. El Valor Predictivo Positivo fue 93,50% y el Valor Predictivo Negativo fue 99,8%. Todos los niños seropositivos fueron tratados con Benznidazol. Se concluye que el uso de Serokit para la toma y conservación de muestras para posterior diagnóstico de infección por Trypanosoma cruzi es recomendable en Centros de Atención Primaria de la Salud que no cuentan con laboratorio.

Chagas disease is caused by the hemoflagelate parasite Trypanosoma cruzi, and represents a main concern in public health. In Argentina, blood transfusion and organ donation are systematically controlled for T. cruzi infection, and vectorial transmission has dropped significantly. The aim of this project was to implement the use of the equipment for collecting capillary blood and conservation in glycerine (Serokit) in the nursery service of Primary Health Care Centers (PHCC) in the city of Salta, and to know the seroprevalence of T. cruzi infection in PHCC patients. To that aim, the serological pair HAI and ELISA was carried out in samples preserved in Serokit, followed by analysis of blood samples taken by venous punction to confirm the results. During a two-year period, 1647 patients that were assisted at 28 PCHC were analyzed, resulting in 1.7% (29/1647) seropositive samples. Positive Predictive Value was 93.5% and Negative Predictive Value was 99.8%. Every seropositive child was given Benznidazole treatment. It can be concluded that use of Serokit for taking and preserving samples to diagnose serologically T. cruzi infection is recommended in PHCC that lack their own biochemistry laboratory.

A doença de Chagas produzida pelo protozoário flagelado Trypanosoma cruzi constitui um grave problema para a Saúde Pública. Na Argentina, o controle sistemático do sangue para transfusão e o do órgão para transplantar, fez com que diminuísse notavelmente a transmissão vetorial. O objetivo deste projeto foi implementar o uso do equipamento para coleta de sangue capilar e conservação em glicerina (Serokit) nos serviços de enfermagem dos Postos de Atenção Primaria da Saúde da cidade de Salta a fim de conhecer a soroprevalência de infecção com Trypanosoma cruzi em pacientes que são atendidos nos mesmos. Foi realizado o par sorológico HAI e ELISA nas amostras conservadas em Serokit e depois nas amostras de sangue retiradas através de uma punção venosa para a confirmação. Durante dois anos de trabalho, foram analisados 1647 pacientes que foram atendidos nos 28 Postos de Saúde, resultando 1.7% (29/1647) soropositivos. O Valor Preditivo Positivo foi Tripae 93.50% e o Valor Preditivo Negativo foi de 99.8%. Todas as crianças soropositivas foram medicadas com Benznidazol. A conclusão é que o uso de Serokit para a tomada e conservação de amostras para posterior diagnóstico de infecção por Trypanosoma cruzi é recomendável nos Postos de Atenção Primária da Saúde onde não existe a disponibilidade de laboratórios.

Plasmodium vivax and Mansonella ozzardi co-infection in north-western Argentina.

A case of co-infection with Plasmodium vivax and Mansonella ozzardi was detected in a blood sample from a person who had shown symptoms of malaria and lived in a city that was close to the Argentina/Bolivia border. The case was detected during a random revision of thick and thin smears from patients diagnosed with malaria from various towns and cities located in north-western Argentina between 1983 and 2001. Trophozoites of P. vivax were observed in the thin blood smear along with M. ozzardi microfilaria (larval form), which presented a long, slender, pointed anucleate tail and the absence of the sheath. This last characteristic is shared with Mansonella perstans, Mansonella streptocerca and Onchocerca volvulus. More rigorously controlled studies to detect other co-infection cases in the area as well as the possibility of importation from Bolivia into Argentina are currently ongoing. The relationship between the malaria parasite and microfilaria, the potential effect of malaria treatment on the development of M. ozzardi, and the possible impact of this microfilaria on the immunity of a person against P. vivax are all still unknown. This contribution constitutes a point of focus for future studies involving the interaction between the parasites and the potential risk that humans are exposed to.

The efficacy of a combined larvicide-adulticide in ultralow volume and fumigant canister formulations in controlling the dengue vector Aedes aegypti (Diptera: Culicidae) in Northwest of Argentina.

The efficacy of an ultralow volume formulation (ULV) and fumigant canister, containing both permethrin and pyriproxyfen, was compared with that of standard permethrin applications in a field assay conducted in Banda del Río Salí, Tucumán (north-western Argentina). Five treatment areas were established: first area was sprayed with a ULV formulation of 10 % permethrin, a second area was treated using a fumigant canister containing 10 % permethrin and 3 % pyriproxyfen, the third area was sprayed with a ULV formulation of 10 % permethrin and 3 % pyriproxyfen, the fourth area with ULV formulation of 10 % permethrin using a portable aerosol generator and the fifth area was a left untreated area. Immature and adult Aedes aegypti individuals placed in containers and sentinel cages were positioned within the treated and control areas. The effects of treatment and time on larval, pupal and adult survival were tested. We also investigated the effects of treatment and time on the numbers of larval and pupal deaths, on the proportion of larvae that metamorphosed into pupae and adults, and on the proportion of dead adults. Larval A. aegypti survivorship in 250 mL containers revealed a significant treatment effect and significant treatment × time interaction 2 and 24 h after the application of the ULV treatment with 10 % permethrin using the portable aerosol generator. The number of dead larvae in 20 L containers differed significantly by treatment and by time. ULV treatment with 10 % permethrin and 10 % permethrin plus 3 % pyriproxyfen using the cold fogger truck mount ULV resulted in the greatest numbers of dead larvae; most larvae died 2 weeks after application. Adult A. aegypti mortality in all treatments did not differ significantly 2 and 24 h after application. In addition, we found no significant differences in adult mortality between cages exposed at 3 m and those at 6 m from the ULV application line. However, there was a significant difference in adult mortality between the 10 % permethrin treatment applied with cold fogger truck mount ULV and that applied using the portable aerosol generator (P < 0.001). The larval index known as Breteau index (BI) was higher before treatment than after treatment in different areas. After the treatments, the lowest value of BI was observed in the area treated with the fumigant canister formulation, and a long-lasting effect was observed with the formulation of 10 % permethrin and 3 % pyriproxyfen.

Spatial patterns of high Aedes aegypti oviposition activity in northwestern Argentina.

BACKGROUND: In Argentina, dengue has affected mainly the Northern provinces, including Salta. The objective of this study was to analyze the spatial patterns of high Aedes aegypti oviposition activity in San Ramón de la Nueva Orán, northwestern Argentina. The location of clusters as hot spot areas should help control programs to identify priority areas and allocate their resources more effectively. METHODOLOGY: Oviposition activity was detected in Orán City (Salta province) using ovitraps, weekly replaced (October 2005-2007). Spatial autocorrelation was measured with Moran's Index and depicted through cluster maps to identify hot spots. Total egg numbers were spatially interpolated and a classified map with Ae. aegypti high oviposition activity areas was performed. Potential breeding and resting (PBR) sites were geo-referenced. A logistic regression analysis of interpolated egg numbers and PBR location was performed to generate a predictive mapping of mosquito oviposition activity. PRINCIPAL FINDINGS: Both cluster maps and predictive map were consistent, identifying in central and southern areas of the city high Ae. aegypti oviposition activity. A logistic regression model was successfully developed to predict Ae. aegypti oviposition activity based on distance to PBR sites, with tire dumps having the strongest association with mosquito oviposition activity. A predictive map reflecting probability of oviposition activity was produced. The predictive map delimitated an area of maximum probability of Ae. aegypti oviposition activity in the south of Orán city where tire dumps predominate. The overall fit of the model was acceptable (ROC=0.77), obtaining 99% of sensitivity and 75.29% of specificity. CONCLUSIONS: Distance to tire dumps is inversely associated with high mosquito activity, allowing us to identify hot spots. These methodologies are useful for prevention, surveillance, and control of tropical vector borne diseases and might assist National Health Ministry to focus resources more effectively.

New records of mosquitoes from northwestern Argentina.

Eleven mosquito species, namely Aedes hastatus, Ae. fulvus, Coquillettidia albicosta, Cq. juxtamansonia, Culex aliciae, Cx. delpontei, Cx. oedipus, Cx. pedroi, Mansonia flaveola, Uranotaenia leucoptera, and Wyeomyia oblita, are recorded for the first time from northwestern Argentina. In addition, 3 species, Cx. brethesi, Limatus durhami, and Ur. nataliae, are reported for the first time from Salta Province. These records extend the geographical distribution of these 3 species to Salta Province. This study also extends the geographical distributions of Cq. nigricans, Cx. chidesteri, and Ma. humeralis to Jujuy Province and of Ae. meprai, Ae. milleri, Ae. oligopistus, Cx. brethesi, Cx. fernandezi, and Cx. tatoi to Tucumán Province.

Spatial heterogeneity and risk maps of community infestation by Triatoma infestans in rural northwestern Argentina.

BACKGROUND: Fifty years of residual insecticide spraying to control Triatoma infestans in the Gran Chaco region of northern Argentina, Paraguay and Bolivia shows that vertically coordinated interventions aiming at full coverage have limited effects and are unsustainable. We quantified the spatial distribution of T. infestans domestic infestation at the district level, identified environmental factors associated with high infestation and then explored the usefulness of risk maps for the spatial stratification of interventions. METHODS AND FINDINGS: We performed spatial analyses of house infestation data collected by the National Chagas Service in Moreno Department, northern Argentina (1999-2002). Clusters of high domestic infestation occurred in the southwestern extreme of the district. A multi-model selection approach showed that domestic infestation clustered in areas of low elevation, with few farmlands, high density of rural houses, high mean maximum land surface temperature, large NDVI, and high percentage of degraded and deforested lands. The best model classified 98.4% of the communities in the training dataset (sensitivity, 93.3%; specificity, 95.4%). The risk map evidenced that the high-risk area only encompassed 16% of the district. By building a network-based transportation model we assessed the operational costs of spatially contiguous and spatially targeted interventions. Targeting clusters of high infestation would have reached -80% of all communities slated for full-coverage insecticide spraying, reducing in half the total time and economic cost incurred by a spatially contiguous strategy. CONCLUSIONS AND SIGNIFICANCE: In disperse rural areas where control programs can accomplish limited coverage, consideration of infestation hot spots can contribute to the design and execution of cost-effective interventions against Chagas disease vectors. If field validated, targeted vertical control in high risk areas and horizontal control in medium to low risk areas may provide both a logistically and economically feasible alternative to blanket vertical insecticide spraying when resources are limited.

Detección, tratamiento y control de niños infectados con trypanosoma cruzi: estudio transversal en centros de atención primaria de Salta, Argentina / Detection, treatment and control of children infected with trypanosoma cruzi: cross-sectional study in centers of primary care of Salta, Argentina

INTRODUCCION: En la ciudad de Salta, la transmisión vectorial de la Enfermedad de Chagas se ha interrumpido desde 1970. Sin embargo, la transmisión congénita continúa debido a la presencia de mujeres infectadas en edad fértil.OBJETIVO: El estudio se propuso: a) incentivar la búsqueda de madres seropositivas, b) diagnosticar y tratar a los niños infectados, c) probar posibles marcadores precoces de curación a fin de evaluar en menor tiempo la efectividad del tratamiento.METODOS: Se trabajó en coordinación con Centro de Atención Primaria de la Salud de la ciudad de Salta. Se aplicaron métodos serológicos convencionales y no convencionales.RESULTADOS: La seroprevalencia en embarazadas en la ciudad de Salta en 2010 fue de 3,1% (61/1946). Se analizaron 57 niños y se encontraron 16 infectados con Trypanosoma cruzi, diagnosticados por microhematocrito o por serología convencional según la edad. Se aplicó tratamiento según las Normas Nacionales de Atención al Infectado Chagásico. Se evaluó la efectividad del tratamiento en 33 niños (edad promedio: 9,6 años), que habían sido tratados durante 2007-2008. El 21,2% (7/33) de esos niños fueron negativos por hemaglutinación en el postratamiento; además, se detectaron 3 antígenos recombinantes como posibles marcadores precoces de cura: Ag SAPA (p=0,0000182), Ag 13 (p=0,0026) y Ag 1 (p=0,02).CONCLUSIONES: Se recomienda el tratamiento y su seguimiento en todos los niños infectados.

INTRODUCTION: In the city of Salta, the vector transmission of Chagas disease has been interrupted since 1970. Nevertheless, congenital transmission is still a problem due to infected women in fertile age.OBJECTIVE: The aims of this study were: a) to search for seropositive mothers, b) to diagnose and to treat infected children, c) to test new antigens in order to detect early markers of treatment effectiveness.METHODS: The study was conducted in coordination with Centers of Primary Health Care in Salta. Conventional and non-conventional serological techniques were applied.RESULTS: During 2010, the Chagas disease prevalence in pregnant women was 3.1% (61/1946). Besides, 16 trypanosoma cruzi-infected children were found, out of 57 analyzed (diagnosed by microhematocrit or by conventional serology, depending on the age). Treatment was applied according to national care guidelines for Chagas disease infected patients. The efficiency of treatment was evaluated in 33 children (average: 9.6 years old), which had been treated during 2007-2008. From these, 21.2% (7/33) were negative for hemagglutination in the post-treatment; and 3 recombinant antigens were detected as possible good markers of treatment effectiveness: Ag SAPA (p=0.0000182), Ag 13 (p=0.0026) and Ag 1 (p=0.02).CONCLUSIONS: Treatment and follow-up should be performed in all infected children.

Detección, tratamiento y control de niños infectados con trypanosoma cruzi: estudio transversal en centros de atención primaria de Salta, Argentina / Detection, treatment and control of children infected with trypanosoma cruzi: cross-sectional study in centers of primary care of Salta, Argentina

INTRODUCCION: En la ciudad de Salta, la transmisión vectorial de la Enfermedad de Chagas se ha interrumpido desde 1970. Sin embargo, la transmisión congénita continúa debido a la presencia de mujeres infectadas en edad fértil.OBJETIVO: El estudio se propuso: a) incentivar la búsqueda de madres seropositivas, b) diagnosticar y tratar a los niños infectados, c) probar posibles marcadores precoces de curación a fin de evaluar en menor tiempo la efectividad del tratamiento.METODOS: Se trabajó en coordinación con Centro de Atención Primaria de la Salud de la ciudad de Salta. Se aplicaron métodos serológicos convencionales y no convencionales.RESULTADOS: La seroprevalencia en embarazadas en la ciudad de Salta en 2010 fue de 3,1% (61/1946). Se analizaron 57 niños y se encontraron 16 infectados con Trypanosoma cruzi, diagnosticados por microhematocrito o por serología convencional según la edad. Se aplicó tratamiento según las Normas Nacionales de Atención al Infectado Chagásico. Se evaluó la efectividad del tratamiento en 33 niños (edad promedio: 9,6 años), que habían sido tratados durante 2007-2008. El 21,2% (7/33) de esos niños fueron negativos por hemaglutinación en el postratamiento; además, se detectaron 3 antígenos recombinantes como posibles marcadores precoces de cura: Ag SAPA (p=0,0000182), Ag 13 (p=0,0026) y Ag 1 (p=0,02).CONCLUSIONES: Se recomienda el tratamiento y su seguimiento en todos los niños infectados.

INTRODUCTION: In the city of Salta, the vector transmission of Chagas disease has been interrupted since 1970. Nevertheless, congenital transmission is still a problem due to infected women in fertile age.OBJECTIVE: The aims of this study were: a) to search for seropositive mothers, b) to diagnose and to treat infected children, c) to test new antigens in order to detect early markers of treatment effectiveness.METHODS: The study was conducted in coordination with Centers of Primary Health Care in Salta. Conventional and non-conventional serological techniques were applied.RESULTS: During 2010, the Chagas disease prevalence in pregnant women was 3.1% (61/1946). Besides, 16 trypanosoma cruzi-infected children were found, out of 57 analyzed (diagnosed by microhematocrit or by conventional serology, depending on the age). Treatment was applied according to national care guidelines for Chagas disease infected patients. The efficiency of treatment was evaluated in 33 children (average: 9.6 years old), which had been treated during 2007-2008. From these, 21.2% (7/33) were negative for hemagglutination in the post-treatment; and 3 recombinant antigens were detected as possible good markers of treatment effectiveness: Ag SAPA (p=0.0000182), Ag 13 (p=0.0026) and Ag 1 (p=0.02).CONCLUSIONS: Treatment and follow-up should be performed in all infected children.

Oviposición diaria de Aedes aegypti en Orán, Salta, Argentina / Daily oviposition activity of Aedes aegypti in Orán, Argentina / Oviposição diária de Aedes aegypti em Orán, Salta (Argentina)

El objetivo del estudio fue determinar los horarios de máxima actividad de oviposición de Aedes aegypti en la ciudad de Orán (noroeste argentino). Se realizaron muestreos quincenales entre noviembre de 2006 y febrero de 2007 (primavera-verano). La ciudad fue dividida en tres zonas (norte, centro, sur), donde fueron seleccionadas al azar las viviendas para colocar dos ovitrampas en el exterior de las mismas. Las ovitrampas fueron reemplazadas cada cuatro horas, desde la mañana (8h) hasta el atardecer (20h). Se registró la mayor cantidad de huevos entre las 16 y 20 h (81 por ciento). Estos datos aportan al conocimiento del vector y, por lo tanto, de la posibilidad de control, pudiendo realizarse las fumigaciones en la franja horaria con mayor actividad de oviposición.

The study aimed to determinate the maximum daily peak of Aedes aegypti oviposition in the city of Oran, northwestern Argentina. Biweekly samplings were taken between November 2006 and February 2007 (spring-summer). The city was divided into three areas (north, center, and south) and households were randomly selected. Two ovitraps were placed outdoors in the selected houses. Ovitraps were replaced every four hours, from morning (8 a.m.) to late afternoon (8 p.m.). The largest number of eggs was recorded between 4 p.m. and 8 p.m. (81 percent). These findings enhance our understanding of the vector and thus its control such as spraying during the hours of peak oviposition activity.

O objetivo do estudo foi determinar os horários de máxima atividade de oviposição de Aedes aegypti na cidade de Orán (noroeste argentino). Foram realizadas coletas quinzenais, entre novembro de 2006 e fevereiro de 2007 (primavera-verão). A cidade foi dividida em três zonas (norte, centro, sul); foram escolhidos aleatoriamente dez domicílios em cada zona e duas ovitrampas foram instaladas no exterior de cada domicílio. As ovitrampas eram trocadas a cada quatro horas, cobrindo desde a manhã (8h) até a noite (20h). A maior quantidade de ovos (81 por cento) foi registrada entre as 16h e 20h. Esses dados aportam conhecimento do vetor e, portanto, a seu controle, como, por exemplo, realizar a fumegação na faixa horária de maior atividade de oviposição.

Daily oviposition activity of Aedes aegypti in Orán, Argentina.

The study aimed to determinate the maximum daily peak of Aedes aegypti oviposition in the city of Oran, northwestern Argentina. Biweekly samplings were taken between November 2006 and February 2007 (spring-summer). The city was divided into three areas (north, center, and south) and households were randomly selected. Two ovitraps were placed outdoors in the selected houses. Ovitraps were replaced every four hours, from morning (8 a.m.) to late afternoon (8 p.m.). The largest number of eggs was recorded between 4 p.m. and 8 p.m. (81%). These findings enhance our understanding of the vector and thus its control such as spraying during the hours of peak oviposition activity.

Prevention of dengue outbreaks through Aedes aegypti oviposition activity forecasting method.

Dengue has affected the north provinces of Argentina, mainly Salta province. The 2009 outbreak, with 5 deaths and >27,000 infected, was the most important, and the first to extend into the central area of the country. This article includes research on seasonal Aedes aegypti abundance variation in Orán City (Salta province), and determination of the date of mosquito population increase and an estimation of the date of maximum rate of increase as well as the intrinsic rate of natural increase (r), to detect the optimal time to apply vector control measures. Between September 2005 and March 2007, ovitraps were randomly distributed in the city to collect Ae. aegypti eggs. The variation observed in the number of collected eggs was described by fitting a third-degree polynomial by the least square method, allowing to determine the time when population increase began (week 1), after the temperate and dry season. Eggs were collected throughout the year, with the highest variation in abundance during the warm and rainy season, and the maximum value registered in February 2007. The rate of increase of the number of eggs laid per week peaked between weeks 9 and 10 after the beginning of the population increase (week 1). Week 1 depends on temperature, it occurs after getting over the thermal threshold and the needed accumulation of 160 degree-day is reached. Consequently, week 1 changes depending on temperature. Peak abundance of eggs during 2005-2006 was recorded on week 15 (after week 1); during 2006-2007, the peak was observed on week 22. Estimation of the intrinsic rate of natural increase (r) of Ae. aegypti is useful not only to determine optimal time to apply vector control measures with better cost-benefit, but also to add an insecticide control strategy against the vector to diminish the possibility of resistance.

Abundance patterns of Anopheles pseudopunctipennis and Anopheles argyritarsis in northwestern Argentina.

Anopheles pseudopunctipennis is an important malaria vector in Argentina but the role of Anopheles argyritarsis in the transmission of the parasite is still unknown. Abundance patterns of both species and their relationship to climatic variables were studied in the subtropical mountainous forest in northwestern Argentina. Adults were collected with CDC light traps from September 2002 to November 2005 in Salta (northern area) and Tucumán (southern area) provinces, from 3 localities in each province. The abundance of both species in localities was compared using the Kruskal-Wallis test, and their changes in abundance in relation to climatic variables were analyzed by Multilevel Poisson Regression. Anopheles argyritarsis was more abundant than A. pseudopunctipennis, and both reached a peak during the spring. There were significant differences in abundance in the northern localities for A. pseudopunctipennis, and between northern and southern localities for A. argyritarsis. Temperature, rainfall and relative humidity were significant predictors of the abundance of these two species.