Assessment of transmission in areas of uncertain endemicity for lymphatic filariasis in Brazil.

BACKGROUND: The objective of the Global Program to Eliminate Lymphatic Filariasis (GPELF) is to phase out this endemic disease as a public health problem by 2020. Validation of elimination is obtained from the World Health Organization through evidence of non-transmission in countries that have already been subjected to mass drug administration (MDA) and in places adjoining these endemic areas. While three municipalities in Brazil have completed MDA, the epidemiological situation remains uncertain in nine adjoining municipalities. To determine the epidemiological status, this study was to perform a review of the literature and a school-based survey to describe the past and recent endemicity of lymphatic filariasis (LF) theses nine municipalities in Brazil. METHODOLOGY/PRINCIPLE FINDINGS: For review of the literature, both formal and informal literature sources were accessed since the first reports of filariasis in the Metropolitan Region of Recife, Brazil. We conducted a school-based survey in 2016 using immunochromatographic card tests (ICTs) among schoolchildren aged 6-10 years living in nine municipalities contiguous with the endemic areas in which MDA was conducted. Our review of the literature identified eight studies involving surveys demonstrating that microfilariae had been circulating in eight of the municipalities since 1967, with a low prevalence of microfilaremia, isolated autochthonous cases, and treatment of individual cases. The school-based survey included 17,222 children in 185 urban schools in the nine areas of Brazil with uncertain endemicity. One child affected by allochthonous transmission was antigen positive based on ICT and lived in a municipality adjacent to Recife; this child's family came from Recife, but no other case was diagnosed within the family. CONCLUSIONS/SIGNIFICANCE: The study results suggest that there is no transmission of LF in the municipalities investigated. However, these areas have population migration and socioenvironmental conditions favorable to mosquito breeding grounds; therefore, surveillance is strongly recommended in these areas.

Screening Aedes aegypti (Diptera: Culicidae) Populations From Pernambuco, Brazil for Resistance to Temephos, Diflubenzuron, and Cypermethrin and Characterization of Potential Resistance Mechanisms.

Resistance to chemical insecticides detected in Aedes aegypti (L.) mosquitoes has been a problem for the National Dengue Control Program (PNCD) over the last years. In order to provide deeper knowledge of resistance to xenobiotics, our study evaluated the susceptibility profile of temephos, diflubenzuron, and cypermethrin insecticides in natural mosquito populations from the Pernambuco State, associating these results with the local historical use of such compounds. Furthermore, mechanisms that may be associated with this particular type of resistance were characterized. Bioassays with multiple temephos and diflubenzuron concentrations were performed to detect and quantify resistance. For cypermethrin, diagnostic dose assays were performed. Biochemical tests were carried out to quantify the activity of detoxification enzymes. In addition, a screening of mutations present in the voltage-gated sodium channel gene (NaV) was performed in samples previously submitted to bioassays with cypermethrin. The populations under study were resistant to temephos and showed a positive correlation between insecticide consumption and the resistance ratio (RR) to the compound. For diflubenzuron, the biological activity ratio (BAR) ranged from 1.3 to 4.7 times, when compared to the susceptible strain. All populations showed resistance to cypermethrin. Altered enzymatic profiles of alpha, p-nitrophenyl acetate (PNPA) esterases and glutathione-S-transferases were recorded in most of these samples. Molecular analysis demonstrated that Arcoverde was the only population that presented the mutated form 1016Ile/Ile. These findings show that the situation is critical vis-à-vis the effectiveness of mosquito control using chemical insecticides, since resistance to temephos and cypermethrin is widespread in Ae. aegypti from Pernambuco.

Evaluation of lymphatic filariasis in endemic area of Brazil where mass drug administration is not required.

Mass drug administration (MDA) is the main counter-transmission strategy of the Global Programme to Eliminate Lymphatic Filariasis. In endemic countries, there are areas where MDA is not required. However, there is no standard approach in these areas, and studies are important to evaluate the epidemiological status. This study aimed to investigate lymphatic filariasis and strategies developed for its control in an area where MDA is not required. Together with the 2018 morbidity evaluation, a survey was conducted using point-of-care immunochromatographic test-AD12 tests for diagnostic screening in an area where MDA is not required. The methodology also included desk research based on Health Department reports of the control activities for lymphatic filariasis during 2003-2016. Among the 934 cases investigated in 2018, there was a 0.64% prevalence of circulating filarial antigen positive, comprising five adults and one 2-year-old child. Six patients aged 39-63 years had filarial disease. Fourteen surveys have already been conducted as control activities, and since 2009, there have been no positive cases. This study showed that the prevalence of antigenemia decreased from 2.97% in 2003 to 0.64% in 2018. Moreover, the transmission of filariasis infection was under control in this area. Our study provides insights into the surveillance phase by identifying areas of low transmission and where MDA is not required. Although we have not identified cases of filarial infection, there is a need to provide services that will provide assist those already affected with morbidity and help reduce and prevent disability.

[Prevalence and worm burden of Schistosomiasis mansoni before and after collective treatment in Jaboatão dos Guararapes, Pernambuco, Brazil]. / Prevalência e carga parasitária da esquistossomose mansônica antes e depois do tratamento coletivo em Jaboatão dos Guararapes, Pernambuco.

OBJECTIVE: to evaluate the effectiveness of collective treatment for Schistosomiasis mansoni in two endemic localities in Jaboatão dos Guararapes-PE. METHODS: we described the prevalence of Schistosomiasis mansoni and the average parasite load before and after collective treatment in the period 2011-2013; data from the Schistosomiasis mansoni Information System and completion of sample surveys reports were used. RESULTS: there is a reduction in 8.9% positivity rate to 2.3% in Barra de Jangada and from 15.7% to 3.5% in Novo Horizonte; there was a decrease of the parasitic load average in Novo Horizonte (67.0 to 52.7 eggs/gram of feces) and increase in Barra de Jangada (23.8 to 91.7 eggs/gram of feces). CONCLUSION: the collective treatment contributed to reducing the rate of positivity in endemic areas.

Prevalência e carga parasitária da esquistossomose mansônica antes e depois do tratamento coletivo em Jaboatão dos Guararapes, Pernambuco / Prevalence and worm burden of Schistosomiasis mansoni before and after collective treatment in Jaboatão dos Guararapes, Pernambuco, Brazil / Prevalencia y carga parasitaria de Esquistosomiasis mansónica antes y después del tratamiento colectivo en Jaboatão dos Guararapes, Pernambuco, Brasil

OBJETIVO: avaliar a efetividade do tratamento coletivo para esquistossomose mansônica em duas localidades endêmicas do município de Jaboatão dos Guararapes-PE. MÉTODOS: foram descritas a prevalência de esquistossomose e a carga média parasitária antes e após tratamento coletivo, no período 2011-2013; foram utilizados dados do Sistema de Informações da Esquistossomose e de relatórios de conclusão dos inquéritos amostrais. RESULTADOS: observou-se redução no percentual de positividade de 8,9% para 2,3% em Barra de Jangada e de 15,7% para 3,5% em Novo Horizonte; ocorreu diminuição da carga média parasitária em Novo Horizonte (de 67,0 para 52,7 ovos/grama de fezes) e incremento em Barra de Jangada (de 23,8 para 91,7 ovos/grama de fezes). CONCLUSÃO: o tratamento coletivo contribuiu para a redução do percentual de positividade nas áreas endêmicas.

OBJECTIVE: to evaluate the effectiveness of collective treatment for Schistosomiasis mansoni in two endemic localities in Jaboatão dos Guararapes-PE. METHODS: we described the prevalence of Schistosomiasis mansoni and the average parasite load before and after collective treatment in the period 2011-2013; data from the Schistosomiasis mansoni Information System and completion of sample surveys reports were used. RESULTS: there is a reduction in 8.9% positivity rate to 2.3% in Barra de Jangada and from 15.7% to 3.5% in Novo Horizonte; there was a decrease of the parasitic load average in Novo Horizonte (67.0 to 52.7 eggs/gram of feces) and increase in Barra de Jangada (23.8 to 91.7 eggs/gram of feces). CONCLUSION: the collective treatment contributed to reducing the rate of positivity in endemic areas.

OBJETIVO: evaluar la efectividad del tratamiento colectivo para Esquistosomiasis mansónica en dos localidades endémicas del municipio de Jaboatão dos Guararapes-PE. MÉTODOS: describimos la prevalencia de Esquistosomiasis mansónica y la carga parasitaria antes y después del tratamiento colectivo en el período 2011-2013; se utilizaron los datos del Sistema de Información de la esquistosomiasis y la finalización de los informes de encuestas por muestreo. RESULTADOS: observamos una reducción de 8,9% para 2,3% en la tasa de positividad en Barra de Jangada y de 15,7% para 3,5% en Novo Horizonte; hubo una disminución del promedio de carga parasitaria en Nuevo Horizonte (de 67,0 para 52,7 huevos/gramo de heces) y un aumento en Barra de Jangada (de 23,8 a 91,7 huevos/gramo de heces). CONCLUSIÓN: el tratamiento colectivo ayudó a reducir la tasa de positividad en las zonas endémicas.

Insecticide resistance in Aedes aegypti populations from Ceará, Brazil.

BACKGROUND: Organophosphates and pyrethroids are used widely in Brazil to control Aedes aegypti, the main vector of dengue viruses, under the auspices of the National Programme for Dengue Control. Resistance to these insecticides is widespread throughout Brazil. In Ceará the vector is present in 98% of districts and resistance to temephos has been reported previously. Here we measure resistance to temephos and the pyrethroid cypermethrin in three populations from Ceará and use biochemical and molecular assays to characterise resistance mechanisms. RESULTS: Resistance to temephos varied widely across the three studied populations, with resistance ratios (RR(95)) of 7.2, 30 and 192.7 in Juazeiro do Norte, Barbalha and Crato respectively. The high levels of resistance detected in Barbalha and Crato (RR(95) ≥ 30) imply a reduction of temephos efficacy, and indeed in simulated field tests reduced effectiveness was observed for the Barbalha population. Two populations (Crato and Barbalha) were also resistant to cypermethrin, whilst Juazeiro do Norte showed only an altered susceptibility. The Ile1011Met kdr mutation was detected in all three populations and Val1016Ile in Crato and Juazeiro do Norte. 1011Met was significantly associated with resistance to cypermethrin in the Crato population. Biochemical tests showed that only the activity of esterases and GSTs, among the tested detoxification enzymes, was altered in these populations when compared with the Rockefeller strain. CONCLUSIONS: Our results demonstrate that two A. aegypti populations from Ceará are under strong selection pressure by temephos, compromising the field effectiveness of this organophosphate. Our results also provide evidence that the process of reducing resistance to this larvicide in the field is difficult and slow and may require more than seven years for reversal. In addition, we show resistance to cypermethrin in two of the three populations studied, and for the first time the presence of the allele 1016Ile in mosquito populations from northeastern Brazil. A significant association between 1011Met and resistance was observed in one of the populations. Target-site mechanisms seem not to be implicated in temephos resistance, reinforcing the idea that for the studied populations, detoxification enzymes most likely play a major role in the resistance to this insecticide.