Desafíos hacia la eliminación de la malaria urbana/peri en Guapi (Colombia), 2016 / Challenges towards elimination of urban/peri-urban malaria in Guapi (Colombia), 2016 / Desafios para a eliminação da malária urbana / peri em Guapi (Colombia), 2016

RESUMEN I: Para mantener la reducción de la malaria, se promueven iniciativas que aceleren la eliminación. En años recientes con la reducción sostenida de la malaria, Colombia hacia el 2021 propone su eliminación en áreas urbanas por lo cual se requieren investigaciones para este desafío O: Establecer la situación epidemiológica de la transmisión de malaria urbana/peri en Guapi 2011-2015 y describir los desafíos en capacidad vectorial, receptividad, infectividad y vulnerabilidad. M: Se realizó un estudio descriptivo, se obtuvieron datos epidemiológicos, entomológicos, parasitológicos, de servicios de salud y socio económicos mediante entrevistas y fuentes secundarias. Con la información se realizaron análisis uni y bivariados, se aplicaron formatos de eliminación de malaria propuestos por la Organización Mundial de la Salud y se analizaron brechas. R: Se notificaron 1097 casos, 39,5% se registraron en el área urbana/peri, y a su vez, el 68% de éstos se concentraron en tres barrios. En capacidad vectorial se identificó como vector primario a anopheles albimanus, con susceptibilidad a los insecticidas, múltiples criaderos y estrategias de instalación de mosquiteros con altas coberturas; en infectividad se encontró predominio de infecciones por p, falciparum, oportunidad de consulta en las primeras 48 horas del 48,1% y automedicación; en vulnerabilidad los casos no urbanos representaron 60,5 % del total. C: La malaria se caracterizó por ser de baja intensidad, focalizada y con picos. Hay significativa receptividad, en infectividad hay retrasos de oportunidad de consulta y existe alta vulnerabilidad por población migrante.

ABSTRACT I: To maintain the reduction of malaria, initiatives that accelerate the elimination are promoted. In recent years with the sustained reduction of malaria, Colombia by 2021 proposes its elimination in urban areas, which requires research for this challenge O: Establish the epidemiological situation of transmission of urban / peri malaria in Guapi 2011-2015 and describe the challenges in vector capacity, receptivity, infectivity and vulnerability. M: A descriptive study was conducted, epidemiological, entomological, parasitological, health and socioeconomic services were obtained through interviews and secondary sources. With the information, univariate and bivariate analyzes were carried out, malaria elimination formats proposed by the World Health Organization were applied and gaps were analyzed. A: 1097 cases were notified, 39.5% were registered in the urban / peri area, and in turn, 68% of these were concentrated in three neighborhoods. In vectorial capacity anopheles albimanus was identified as the primary vector with susceptibility to insecticides, multiple hatcheries and strategies for installing mosquito nets with high coverage; In infectivity, predominance of p. falciparum, 48.1% consultation opportunity in the first 48 hours and self-medication; in vulnerability, non-urban cases represented 60.5% of the total. C: Malaria was characterized by being of low intensity, focused and with spikes. There is significant receptivity, in infectiousness there are delays in the opportunity of consultation and there is high vulnerability due to migrant population.

RESUMO I: Para manter a redução da malária, são promovidas iniciativas que aceleram a eliminação. Nos últimos anos, com a redução sustentada da malária, a Colômbia propõe, até 2021, sua eliminação nas áreas urbanas, o que requer pesquisa para esse desafio O: Estabelecer a situação epidemiológica da transmissão da malária urbana / peri-Guapi 2011-2015 e descrever os desafios em capacidade de vetores, receptividade, infecciosidade e vulnerabilidade. M: Estudo descritivo, epidemiológico, entomológico, parasitológico, de saúde e socioeconómico, obtido por meio de entrevistas e fontes secundárias. Com as informações, foram realizadas análises univariadas e bivariadas, os formatos de eliminação de malária propostos pela Organização Mundial da Saúde foram aplicados e as lacunas foram analisadas. R: 1097 casos foram notificados, 39,5% foram registrados na área urbana / peri e, por sua vez, 68% destes foram concentrados em três bairros. Em capacidade vetorial, anopheles albimanus foi identificado como vetor primário, com suscetibilidade a inseticidas, múltiplos incubatórios e estratégias para a instalação de redes mosquiteiras com alta cobertura; Na infectividade, predomínio de p. falciparum, 48,1% de oportunidade de consulta nas primeiras 48 horas e automedicação; em vulnerabilidade, os casos não urbanos representaram 60,5% do total. C: A malária foi caracterizada por ser de baixa intensidade, focada e com picos. Há uma receptividade significativa, na infecciosidade há atrasos na oportunidade de consulta e há alta vulnerabilidade devido à população migrante.

Generalized additive model of Plasmodium vivax malaria incidence and meteorological factors / 中国人兽共患病学报

This paper aims to find out the impacts of meteorological factors on malaria transmission by exploring the relationship between monthly local malaria cases and meteorological factors in Tengchong county,so as to develop malaria control strategy.Plasmodium vivax malaria incidence data and meteorological data including monthly mean temperature,maximum temperature,minimum temperature,rainfall,relative humidity,and minimum humidity in Tengchong County,Yunnan from 2005 to 2010 were provided by the Chinese Center for Disease Control and China Meteorological Administration.The correlation between malaria incidence and meteorological factors was analyzed using Pearson correlation analysis.The generalized additive model (GAM) was applied to investigate the relationship between monthly local malaria cases and meteorological factors.Results showed that there was a weak positive correlation between minimum temperature,mean relative humidity as well as minimum relative humidity and local malaria incidences.While a complex nonlinear relationship between the vectorial capacity,relative humidity and the incidence of malaria was detected.Malaria transmission increases when the vectorial capacity was greater than 10 (VCAP＞10) or the average relative humidity was between 55％ and 70％.The malaria transmission declines when relative humidity above 70％.The relationship between meteorological factors and the incidence of local malaria is well explained by GAM,and there is a complex nonlinear relationship between vectorial capacity,relative humidity and malaria incidence.

Estimation of vectorial capacity of Anopheles minimus Theobald & An. fluviatilis James (Diptera: Culicidae) in a malaria endemic area of Odisha State, India.

Background & objectives: Anopheles minimus and An. fluviatilis were incriminated as the major malaria vectors in Keonjhar district of Odisha State recently. This study was carried out to elucidate the potential role of these two vector species in transmission of malaria during different seasons, and vectorial capacity of these species was also estimated. Methods: Three hilly and forested villages of Keonjhar district were randomly selected. Vectorial capacity (C) was calculated using the Macdonald’s formula as modified by Garret-Jones. The human landing density of the vector species was obtained from all night human landing collections (bait protected by bed-net). Man feeding habit was estimated by multiplying the human blood index with feeding frequency, which was obtained on daily basis from the duration of gonotrophic cycle. The probability of survival through the extrinsic incubation cycle was calculated from the probability of survival through one day and duration of sporogonic cycle. Results: The estimated vectorial capacity of An. minimus varied between 0.014 and 1.09 for Plasmodium falciparum (Pf) and between 0.1 and 1.46 for P. vivax (Pv). The C of An. minimus for both Pf and Pv was higher during rainy season than the other two seasons. The estimated C of An. fluviatilis varied between 0.04 and 1.28 for Pf and between 0.20 and 1.54 for Pv. Interpretation & conclusions: Based on the estimated values of vectorial capacity of the two vector species, the area could be stratified and such stratification would reflect the difference in the intensity of transmission between different strata and accordingly the appropriate control strategy could be adopted for each stratum.

Vectorial capacity, basic reproduction number, force of infection and all that: formal notation to complete and adjust their classical concepts and equations

A dimensional analysis of the classical equations related to the dynamics of vector-borne infections is presented. It is provided a formal notation to complete the expressions for the Ross' Threshold Theorem, the Macdonald's basic reproduction "rate" and sporozoite "rate", Garret-Jones' vectorial capacity and Dietz-Molineaux-Thomas' force of infection. The analysis was intended to provide a formal notation that complete the classical equations proposed by these authors.

Distribution of sibling species of Anopheles culicifacies s.l. and Anopheles fluviatilis s.l. and their vectorial capacity in eight different malaria endemic districts of Orissa, India

The study was undertaken in eight endemic districts of Orissa, India, to find the members of the species complexes of Anopheles culicifacies and Anopheles fluviatilis and their distribution patterns. The study area included six forested districts (Keonjhar, Angul, Dhenkanal, Ganjam, Nayagarh and Khurda) and two non-forested coastal districts (Puri and Jagatsingpur) studied over a period of two years (June 2007-May 2009). An. culicifacies A, B, C and D and An. fluviatilis S and T sibling species were reported. The prevalence of An. culicifacies A ranged from 4.2-8.41 percent, B from 54.96-76.92 percent, C from 23.08-33.62 percent and D from 1.85-5.94 percent (D was reported for the first time in Orissa, except for occurrences in the Khurda and Nayagarh districts). The anthropophilic indices (AI) were 3.2-4.8 percent, 0.5-1.7 percent, 0.7-1.37 percent and 0.91-1.35 percent for A, B, C and D, respectively, whereas the sporozoite rates (SR) were 0.49-0.54 percent, 0 percent, 0.28-0.37 percent and 0.41-0.46 percent for A, B, C and D, respectively. An. fluviatilis showed a similarly varied distribution pattern in which S was predominant (84.3 percent overall); its AI and SR values ranged from 60.7-90.4 percent and 1.2-2.32 percent, respectively. The study observed that the co-existence of potential vector sibling species of An. culicifacies (A, C and D) and An. fluviatilis S (> 50 percent) was responsible for the high endemicity of malaria in forested districts such as Dhenkanal, Keonjhar, Angul, Ganjam, Nayagarh and Khurda (> 5 percent slide positivity rate). Thus, the epidemiological scenario for malaria is dependent on the distribution of the vector sibling species and their vectorial capacity.

Container productivity, daily survival rates and dispersal of Aedes aegypti mosquitoes in a high income dengue epidemic neighbourhood of Rio de Janeiro: presumed influence of differential urban structure on mosquito biology

Different urban structures might affect the life history parameters of Aedes aegypti and, consequently, dengue transmission. Container productivity, probability of daily survival (PDS) and dispersal rates were estimated for mosquito populations in a high income neighbourhood of Rio de Janeiro. Results were contrasted with those previously found in a suburban district, as well as those recorded in a slum. After inspecting 1,041 premises, domestic drains and discarded plastic pots were identified as the most productive containers, collectively holding up to 80 percent of the total pupae. In addition, three cohorts of dust-marked Ae. aegypti females were released and recaptured daily using BGS-Traps, sticky ovitraps and backpack aspirators in 50 randomly selected houses; recapture rate ranged from 5-12.2 percent within cohorts. PDS was determined by two models and ranged from 0.607-0.704 (exponential model) and 0.659-0.721 (non-linear model), respectively. Mean distance travelled varied from 57-122 m, with a maximum dispersal of 263 m. Overall, lower infestation indexes and adult female survival were observed in the high income neighbourhood, suggesting a lower dengue transmission risk in comparison to the suburban area and the slum. Since results show that urban structure can influence mosquito biology, specific control strategies might be used in order to achieve cost-effective Ae. aegypti control.

Natural vertical transmission by Stegomyia albopicta as dengue vector in Brazil / Transmissão vertical natural de Stegomyia albopicta como vetor de dengue no Brasil

The mosquito Stegomyia albopicta is among the most important arbovirus vectors in the world, particularly for Dengue viruses. Their natural history suggests that biologically these viruses are highly adapted to their mosquito hosts and they were most likely mosquito viruses prior to becoming adapted to lower primates and humans. As well as being maintained by transmission among susceptible humans, Dengue viruses may also be maintained by vertical transmission in mosquitoes during inter-epidemic periods. The larvae and mosquitoes of Stegomyia albopicta were used to identify the vertical transmission of the dengue virus in nature and to confirm the vectorial capacity concerning the Dengue virus type 2 infection. The minimum infection rate concerning S. albopicta infection with the Dengue virus was 1:36.45. In Brazil this was the first time that high minimum infection rates of vertical transmission of S. albopicta were detected in this species.

O mosquito Stegomyia albopicta está dentre os mais importantes vetores de arbovírus do mundo, particularmente para o Dengue virus. A história natural sugere que biologicamente esses vírus são altamente adaptados aos seus mosquitos vetores e foram, provavelmente, os vírus que infectavam mosquitos antes de se tornarem adaptados a primatas não humanos e humanos. Além de serem mantidos entre os homens susceptíveis, os Dengue viruses podem também ser mantidos pela transmissão vertical em mosquitos durante os períodos interepidêmicos. As larvas e mosquitos da espécie Stegomyia albopicta foram utilizados para a identificação da transmissão vertical do vírus dengue na natureza e para confirmar a capacidade vetorial em relação à infecção pelo DENV-2 infection. A taxa mínima de infecção em relação à infecção do S. albopicta com o Dengue virus foi de 1:36,45. No Brasil, esta é a primeira vez que altas taxas de infecção mínima da transmissão vertical de S. albopicta foram detectadas nessa espécie.

Investigation on the Impact of Imported Cases on Filariasis Elimination Program in Shandong Province / 中国寄生虫学与寄生虫病杂志

Objective To study the impact of imported filariasis cases on the elimination program in different areas of Shandong Province. Methods Dezhou was selected as former low endemic area and Yicheng as former high endemic area. Blood examination was carried out for both mobile population and local people for microfilariae(Mf). Mosquitoes were caught in field and dissected to count the ratio of those having laid eggs and the natural filarial infection rate. Mosquitoes reared at different temperatures were fed with Mf-positive blood and dissected after certain time period to observe the development of the larvae. The vectorial capacity and case transmission quantity were calculated and compared with those from different areas. Results The Mf positive rate of inflow population was 3.18% in average. No case was detected from 9 411 local residents after blood exam in Dezhou while 2 out of 692 local residents were found Mf positive in Yicheng. Mosquitoes'natural infection rate was 3.81% but no third stage larva was found. The shortest time period needed for the larva to develop into an infective stage was 16 days in Dezhou and 11 days in Yicheng. The time period from blood meal to egg-laying on average was 4. 95 days in Dezhou and 4.33 days in Yicheng. The ratio of vectorial capacity and case transmission quantity was 1:4.41 and 1:5. 82 respectively in Dezhou and Yicheng. Conclusion Filarial transmission seems unlikely in Dezhou for its low vectorial capacity and low transmission quantity resulted from low and evidently fluctuating temperature in the north. A low level filarial transmission may be possible in former high-endemic area such as Yicheng if there are as many imported cases as in Dezhou.

The Role of Anopheles anthropophagus in Malaria Transmission in in Xinyang City of Henan Province / 中国寄生虫学与寄生虫病杂志

Objective To study the role of Anopheles anthropophagus in malaria transmission and transmission threshold so as to provide basis for vector surveillance and malaria control strategy. Methods Parasitological and entomological methods were used in the investigation at 5 villages of Xinyang City, Henan Province. Results From July to August, 1999, 74 febrile cases (10^9% of the total population) were examined. Among them 50 were infected, the incidence in the population of surveyed spots was 7^4%. Active detection was made in another randomly selected two villages and found that the parasite rate in the inhabitants was 2^0%, and the positive rate of IFA was 8^4%. Only vivax malaria was detected. An.anthropophagus and An.sinensis were collected, with An.anthropophagus as the predominant one in human dwellings. The estimated man\|biting rate and the human blood index were 4^9388 and 0^7858 respectively. The vectorial capacity of An. anthropophagus was 5^5296. The critical man\|biting rate of An.anthropophagus was 0^2407 as calculated by the formula (ma=-rlnP/abP\+n) according to Macdonald′s model.The local man\|biting rate was 20 times higher than that of the critical man\|biting rate. Conclusion The results demonstrated that An.anthropophagus is the principal vector in malaria transmission in the area. The findings imply that the critical man\|biting rate is of practicable importance in vector surveillance.