Burden of lymphatic filariasis morbidity in an area of low endemicity in Brazil

Lymphatic Filariasis: A Systematic Review on Morbidity and Its Repercussions in Countries in the Americas

The Global Program to Eliminate Lymphatic Filariasis (GPELF) is a program that aims to eliminate lymphatic filariasis by 2030. The GPELF strategy is based on interrupting transmission using mass drug administration (MDA) and, in parallel, managing morbidity cases. However, it has been seen that there is a shortage of research in the literature and public policies regarding this last pillar. In this study, we reviewed the literature and available information regarding the burden of filarial morbidity. In addition, we identified that in the Americas, the implementation of structured services with regard to morbidity assistance in the Americas was scarce. We formed a review that aimed to assess the pathogenesis, epidemiology, repercussions, and treatment of filarial morbidity in countries in the Americas where lymphatic filariasis is endemic. Structured searches were carried out on PubMed, LILACS, Scopus, and Web of Science databases without time and language restrictions. Three reviewers evaluated the 2150 studies and performed data extraction, and quality assessment by assigning scores to the studies found. The current literature and available information on the burden of filarial morbidity, as well as the implementation of structured services with regard to morbidity assistance in the Americas, were all found to be scarce. Now that this knowledge gap has been identified, both health services and researchers need to seek the implementation and enhancement of the maintenance of GPELF strategies that relate to the morbidity pillar.

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.

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.

Microcephaly epidemic related to the Zika virus and living conditions in Recife, Northeast Brazil

Background

Starting in August 2015, there was an increase in the number of cases of neonatal microcephaly in Northeast Brazil. These findings were identified as being an epidemic of microcephaly related to Zika virus (ZIKV) infection. The present study aims to analyse the spatial distribution of microcephaly cases in Recife (2015–2016), which is in Northeast Brazil, and its association with the living conditions in this city.

Methods

This was an ecological study that used data from reported cases of microcephaly from the State Health Department of Pernambuco (August 2015 to July 2016). The basic spatial unit of analysis was the 94 districts of Recife. The case definition of microcephaly was: neonates with a head circumference of less than the cut-off point of −2 standard deviations below the mean value from the established Fenton growth curve. As an indicator of the living conditions of the 94 districts, the percentage of heads of households with an income of less than twice the minimum wage was calculated. The districts were classified into four homogeneous strata using the K-means clustering algorithm. We plotted the locations of each microcephaly case over a layer of living conditions.

Results

During the study period, 347 microcephaly cases were reported, of which 142 (40.9%) fulfilled the definition of a microcephaly case. Stratification of the 94 districts resulted in the identification of four strata. The highest stratum in relation to the living conditions presented the lowest prevalence rate of microcephaly, and the overall difference between this rate and the rates of the other strata was statistically significant. The results of the Kruskal-Wallis test demonstrated that there was a strong association between a higher prevalence of microcephaly and poor living conditions. After the first 6 months of the study period, there were no microcephaly cases recorded within the population living in the richest socio-economic strata.

Conclusion

This study showed that those residing in areas with precarious living conditions had a higher prevalence of microcephaly compared with populations with better living conditions.