Site Occupancy by Aedes aegypti in a Subtropical City is Most Sensitive to Control during Autumn and Winter Months.

The Aedes aegypti mosquito inhabits most tropical and subtropical regions of the globe, where it transmits arboviral diseases of substantial public health relevance, such as dengue fever. In subtropical regions, Ae. aegypti often presents an annual abundance cycle driven by weather conditions. Because different population states may show varying responses to control, we are interested in studying what time of the year is most appropriate for control. To do so, we developed two dynamic site-occupancy models based on more than 200 weeks of mosquito trapping data from nearly 900 sites in a subtropical Brazilian city. Our phenomenological, Markovian models, fitted to data in a Bayesian framework, accounted for failure to detect mosquitoes in two alternative ways and for temporal variation in dynamic rates of local extinction and colonization of new sites. Infestation varied from nearly full cover of the city area in late summer, to between 10% and 67% of sites occupied in winter depending on the model. Sensitivity analysis reveals that changes in dynamic rates should have the greatest impact on site occupancy during autumn and early winter months, when the mosquito population is declining. We discuss the implications of this finding to the timing of mosquito control.

Meteorological variables and mosquito monitoring are good predictors for infestation trends of Aedes aegypti, the vector of dengue, chikungunya and Zika.

BACKGROUND: Aedes aegypti is an important vector for arboviroses and widely distributed throughout the world. Climatic factors can influence vector population dynamics and, consequently, disease transmission. The aim of this study was to characterize the temporal dynamics of an Ae. aegypti population and dengue cases and to investigate the relationship between meteorological variables and mosquito infestation. METHODS: We monitored and analyzed the adult female Ae. aegypti population, the dengue-fever vector, in Porto Alegre, a subtropical city in Brazil using the MI-Dengue system (intelligent dengue monitoring). This system uses sticky traps to monitor weekly infestation indices. We fitted generalized additive models (GAM) with climate variables including precipitation, temperature and humidity, and a GAM that additionally included mosquito abundance in the previous week as an explanatory variable. Logistic regression was used to evaluate the effect of adult mosquito infestation on the probability of dengue occurrence. RESULTS: Adult mosquito abundance was strongly seasonal, with low infestation indices during the winters and high infestation during the summers. Weekly minimum temperatures above 18 °C were strongly associated with increased mosquito abundance, whereas humidity above 75% had a negative effect on abundance. The GAM model that included adult mosquito infestation in the previous week adjusted and predicted the observed data much better than the model which included only meteorological predictor variables. Dengue was also seasonal and 98% of all cases occurred at times of high adult Ae. aegypti infestation. The probability of dengue occurrence increased by 25%, when the mean number of adult mosquitos caught by monitoring traps increased by 0.1 mosquitoes per week. CONCLUSIONS: The results suggest that continuous monitoring of dengue vector population allows for more reliable predictions of infestation indices. The adult mosquito infestation index was a good predictor of dengue occurrence. Weekly adult dengue vector monitoring is a helpful dengue control strategy in subtropical Brazilian cities.

Perfil epidemiológico do atendimento antirrábico humano em Porto Alegre, RS, Brasil / Epidemiologic profile of human anti-rabies treatment in Porto Alegre, RS, brazil

As mordeduras animais são injúrias que se destacam pela possibilidade de transmissão da raiva, sendo esta uma doença com letalidade de 100 por cento. O objetivo deste trabalho foi caracterizar o perfil epidemiológico do atendimento antirrábico humano pós-exposição e analisar a adequação de sua indicação. Foi realizado estudo transversal, tendo como fonte de dados a ficha de notificação do SINAN preenchida nos serviços de saúde pelos profissionais responsáveis pelo atendimento no segundo semestre de 2006. Entre os 2.223 casos investigados, 50,3 por cento dos indivíduos eram do sexo masculino; a faixa etária com mais agressões foi a de 20 a 59 anos (47,6 por cento); a forma de agressão responsável pela maior número de atendimentos foi a mordedura (87,4 por cento) e 35,3 por cento das agressões ocorreram nos membros inferiores. A espécie animal predominante foi a canina (91,7 por cento). Em relação ao tratamento prescrito, 78,1 por cento dos sujeitos receberam indicação de vacina e 6,4 por cento, soro. Foram considerados como adequadamente indicados 96,2 por cento dos tratamentos. Embora os tratamentos tenham sido corretamente prescritos, faz-se necessária a valorização da observação do animal agressor para diminuir o número de tratamentos dispensados.

Animal bites are injuries that carry the risk of rabies transmission, a disease with a 100 percent mortality rate. The purpose of this study was to determine the epidemiologic profiles of post exposure human anti-rabies treatments and to analyze whether prescriptions were appropriate. This cross-sectional study collected data from the forms of the Brazilian Notification System (Sistema Nacional Agravos de Notificação - SINAN), which were filled out by the professionals responsible for treatment in healthcare services in the second semester of 2006. Of the 2,223 cases identified, 50.3 percent of the individuals were male, the age group with the greatest number of cases was 20 to 59 years (47.6 percent); the type of injury responsible for the largest number of medical consultations was animal bite (87.4 percent), and 35.3 percent of the injuries were in the lower extremities. Dogs were the animals that caused the most injuries (91.7 percent). The analysis of type of treatment showed that vaccination was prescribed for 78.1 percent of the individuals, and anti-rabies serum, for 6.4 percent. Of the all treatments, 96.2 percent were classified as correctly prescribed. Although treatments were classified as necessary, the option of keeping animals that cause aggressions under observation should be considered so that the number of treatments administered can be reduced.

[Epidemiologic profile of human anti-rabies treatment in Porto Alegre, RS, brazil]. / Perfil epidemiológico do atendimento antirrábico humano em Porto Alegre, RS, Brasil.

Animal bites are injuries that carry the risk of rabies transmission, a disease with a 100% mortality rate. The purpose of this study was to determine the epidemiologic profiles of post exposure human anti-rabies treatments and to analyze whether prescriptions were appropriate. This cross-sectional study collected data from the forms of the Brazilian Notification System (Sistema Nacional Agravos de Notificação - SINAN), which were filled out by the professionals responsible for treatment in healthcare services in the second semester of 2006. Of the 2,223 cases identified, 50.3% of the individuals were male, the age group with the greatest number of cases was 20 to 59 years (47.6%); the type of injury responsible for the largest number of medical consultations was animal bite (87.4%), and 35.3% of the injuries were in the lower extremities. Dogs were the animals that caused the most injuries (91.7%). The analysis of type of treatment showed that vaccination was prescribed for 78.1% of the individuals, and anti-rabies serum, for 6.4%. Of the all treatments, 96.2% were classified as correctly prescribed. Although treatments were classified as necessary, the option of keeping animals that cause aggressions under observation should be considered so that the number of treatments administered can be reduced.

[Abandon reasons of post-exposure human anti-rabies treatment in Porto Alegre (RS, Brazil)]. / Motivos de abandono do tratamento antirrábico humano pós-exposição em Porto Alegre (RS, Brasil).

In Brazil, rabies is an endemic disease with a fatality rate of 100%. The number of cases has decreased, but the number of cases for treatment after exposure and treatment dropout is still high. This study investigated the causes of anti-rabies treatment abandon, after exposure, in Porto Alegre (RS, Brazil), from July to December 2006. A case series was designed. Two hundred and eighty abandon cases were selected through randomized systematic sampling, out of 962 registered in Sinan. Data was collected in people's homes through interviews, by means of a questionnaire. According to the interviewees, 66.4% concluded the prescribed number of vaccines. This information was not registered in Sinan. Among the subjects confirmed of abandoning the treatment (94/280), 24.5% reported that they thought it was not necessary to complete the treatment, while 13.8% felt that they did not receive clear guidelines about what to do. Health services attempted to contact absents in only 19.2% of the cases. Data entered in Sinan present failures. These occurred because patients started treatment at one health service and continued in a different one. As a consequence, information about the conclusion of the treatment was not entered into the system.

Motivos de abandono do tratamento antirrábico humano pós-exposição em Porto Alegre (RS, Brasil) / Abandon reasons of post-exposure human anti-rabies treatment in Porto Alegre (RS, Brazil)

A raiva é uma doença endêmica no Brasil, com letalidade de 100 por cento. O número de casos tem diminuído, porém o de tratamento pós-exposição continua elevado, assim como o de abandono. O objetivo do estudo foi investigar as causas do abandono do tratamento antirrábico humano pós-exposição em Porto Alegre (RS), no segundo semestre de 2006. Foi utilizado o delineamento de série de casos, sendo selecionados 280 casos por amostragem aleatória sistemática entre os 962 registrados no Sinan como abandono de tratamento. Os dados foram coletados em entrevistas domiciliares, utilizando-se questionário específico. Segundo os entrevistados, 66,4 por cento concluíram o número de vacinas prescritas, não estando esses dados registrados no Sinan. Entre aqueles que foram confirmados como abandono (94/280), 24,5 por cento referiram não ter considerado necessário completá-lo, e 13,8 por cento não se sentiram orientados sobre como proceder. Somente em 19,1 por cento dos casos houve a busca ativa dos faltosos pelos serviços de saúde. O registro no Sinan apresenta falhas. Estas ocorrem devido ao fato de o paciente iniciar o tratamento em um serviço de saúde e dar continuidade em outro, não havendo retroalimentação do sistema com dados sobre a sua conclusão.

In Brazil, rabies is an endemic disease with a fatality rate of 100 percent. The number of cases has decreased, but the number of cases for treatment after exposure and treatment dropout is still high. This study investigated the causes of anti-rabies treatment abandon, after exposure, in Porto Alegre (RS, Brazil), from July to December 2006. A case series was designed. Two hundred and eighty abandon cases were selected through randomized systematic sampling, out of 962 registered in Sinan. Data was collected in people's homes through interviews, by means of a questionnaire. According to the interviewees, 66.4 percent concluded the prescribed number of vaccines. This information was not registered in Sinan. Among the subjects confirmed of abandoning the treatment (94/280), 24.5 percent reported that they thought it was not necessary to complete the treatment, while 13.8 percent felt that they did not receive clear guidelines about what to do. Health services attempted to contact absents in only 19.2 percent of the cases. Data entered in Sinan present failures. These occurred because patients started treatment at one health service and continued in a different one. As a consequence, information about the conclusion of the treatment was not entered into the system.

Espécies e prevalência das infestações por carrapatos em cães de rua da cidade de Porto Alegre, RS, Brasil / Species and prevalence of ticks infestations on stray dogs in Porto Alegre city, RS, Brazil

O objetivo deste trabalho foi identificar as espécies de carrapatos que parasitam os cães da área urbana de Porto Alegre e conhecer suas prevalências nesta população. Para isso, foram examinados 450 cães de rua de Porto Alegre, colhidos os carrapatos nos animais infestados e estes identificados ao estereomicroscópio por espécie e por estágio. Dentre os animais examinados, 52,44 por cento albergavam carrapatos e destes, 93,22 por cento estavam parasitados por Rhipicephalus sanguineus, 2,97 por cento por Amblyomma aureolatum e 3,81 por cento pelas duas espécies simultaneamente. Do total de carrapatos colhidos, a espécie mais abundante nos animais foi R. sanguineus representando 99,43 por cento desse total; foram encontrados ínstares de todos os estágios parasitários de R. sanguineus e só do estágio adulto de A.aureolatum.

The purpose of this study was to identify and to know the prevalence of ticks recovered from dogs of urban area of Porto Alegre, RS. Four hundred and fifty stray dogs were examined and the ticks found were identified according to the species and parasitic stage. A percentage of 52.44 percent of those dogs were infested with ticks, among these, 93.22 percent were parasitized by Rhipicephalus sanguineus, 2.97 percent by Amblyomma aureolatum and 3.81 percent by both species. R. sanguineus was the more prevalent species among infested animals representing 99.43 percent of the total number of ticks sampled. All parasitic stages of R. sanguineus were present on the stray dogs but only the adult stage of A. aureolatum was found.