Lymphatic filariasis among children and adolescents: spatial identification via socio-environmental indicators to define priority areas for elimination.

BACKGROUND: The occurrence of lymphatic filariasis (LF) and its transmission dynamics among children and adolescents are still not clearly elucidated. The aim of this study was to describe the spatial distribution of microfilaremia and its relationship with socio-environmental variables, thereby identifying areas at greater risk of transmission. METHODS: An ecological study was conducted, in which the analysis unit was formed by districts of the municipality of Jaboatão dos Guararapes in the state of Pernambuco, Brazil. The data source was a parasitological survey. Inadequate sewage disposal, number of people in the household and income of between 0.5 and 1 minimum salary were used to construct the socio-environmental indicator. The districts were then grouped according to the indicator into three risk strata, using the k-means clustering technique. RESULTS: In the study, 96/8670 (1.1%) of the population were found to present microfilaremia. The high-risk stratum had a mean prevalence rate of 1.9% and a risk of 2.56 (p<0.05), in relation to the low-risk stratum. The middle stratum grouped the households that presented an intermediate risk of transmission, with a prevalence rate of 1.92%. CONCLUSIONS: The indicator used is a promising tool that enables the precise measurement of the relationship between social deprivation and the prevalence of filarial infection among children. Thus, it can be used to plan control and elimination actions.

Spatial analysis and privation index to identify urban areas with a high risk of lymphatic filariasis.

OBJECTIVE: To evaluate composite living conditions as indicators of urban areas with a higher risk of filariasis transmission. METHODS: This was an ecological study in the municipality of Jaboatão dos Guararapes, in Brazil. The analysis units were census tracts. The study was divided into three phases. First, data gathered during an epidemiological investigation were analysed. Secondly, living condition indicators were drawn up and the relationship between these indicators and microfilaremia prevalence rates was analysed. Thirdly, positive cases were georeferenced with a view to identifying spatial concentration using kernel intensity estimates. Two composite living condition indicators were calculated: a socio-environmental risk index (in the form of scores) and a social deprivation index (through principal-component factor analysis). RESULTS: Of 23,673 individuals examined, 1.4% had microfilaremia. According to the two indicators, greater prevalence was found in the high-risk strata, and this association was confirmed by the kernel intensity estimates. CONCLUSIONS: Classification of census tracts into risk strata showed the relevance of socio-economic factors and environmental conditions in identifying priority areas in urban spaces for interventions by the surveillance services and in planning filariasis control. Spatial analysis also proved to be an important tool for building up a territorially based surveillance system. These indicators, used in association with spatial analysis, are an instrument to be used by the Global Programme to Eliminate Lymphatic Filariasis.

The present situation regarding lymphatic filariasis in Cabo de Santo Agostinho, Pernambuco, Northeast Brazil.

A cross-sectional population-based survey on the occurrence of lymphatic filariasis was carried out in the municipality of Cabo de Santo Agostinho, Pernambuco, Northeast Brazil. 7,650 individuals of both sexes were examined (from 1,416 households) of whom six tested positive for microfilaria according to the thick blood diagnostic test. The age of the individuals examined varied from 0 to 98 (averaging 26.6 years), whilst the age of the microfilaria-positive individuals varied from 11 to 29, averaging 22.5 years. Five of the six positive cases were male. These cases were residents of the following areas: Pista Preta (one case); Ponte dos Carvalhos (four cases); and Pontezinha (one case). This last case from Pontezinha was autochthonous. Of the individuals examined, 109 (1.4%) cited complaints relating to filariasis. These results suggest that filariasis is being transmitted in the municipality of Cabo de Santo Agostinho, a finding that establishes the need to carry out disease control activities, and to collaborate with the planning of the national programme for the elimination of filariasis.

The present situation regarding lymphatic filariasis in Cabo de Santo Agostinho, Pernambuco, Northeast Brazil / A situação da filariose linfática em Cabo de Santo Agostinho, Pernambuco, nordeste do Brasil

A cross-sectional population-based survey on the occurrence of lymphatic filariasis was carried out in the municipality of Cabo de Santo Agostinho, Pernambuco, Northeast Brazil. 7,650 individuals of both sexes were examined (from 1,416 households) of whom six tested positive for microfilaria according to the thick blood diagnostic test. The age of the individuals examined varied from 0 to 98 (averaging 26.6 years), whilst the age of the microfilaria-positive individuals varied from 11 to 29, averaging 22.5 years. Five of the six positive cases were male. These cases were residents of the following areas: Pista Preta (one case); Ponte dos Carvalhos (four cases); and Pontezinha (one case). This last case from Pontezinha was autochthonous. Of the individuals examined, 109 (1.4 percent) cited complaints relating to filariasis. These results suggest that filariasis is being transmitted in the municipality of Cabo de Santo Agostinho, a finding that establishes the need to carry out disease control activities, and to collaborate with the planning of the national programme for the elimination of filariasis.

Foi realizado um estudo seccional de base populacional, sobre a ocorrência da filariose linfática bancroftiana no município do Cabo de Santo Agostinho, Pernambuco, nordeste do Brasil. Foram examinados 7.650 indivíduos de ambos os sexos, residentes em 1.416 domicílios, dos quais 7.644 indivíduos foram identificados como negativos para filariose e seis casos positivos. A idade dos indivíduos examinados variou de 0 a 98 anos (média de 26,6 anos), enquanto que a idade dos positivos variou de 11 a 29 anos, média de 22,5 anos. Cinco dos seis casos eram do sexo masculino. Os indivíduos microfilarêmicos eram residentes na localidade de Pista Preta (01 caso) e nos distritos de Ponte dos Carvalhos (04 casos) e de Pontezinha (01 caso), sendo esse ultimo autóctone. Entre as pessoas examinadas 109 (1,4 por cento) apresentaram queixas clínicas relacionadas à filariose. Esses resultados apontam para a existêcia de transmissão da filariose no município do Cabo de Santo Agostinho, dado esse que determina a necessidade de se estabeceler atividades de controle da endemia, assim como vem colaborar no planejamento do programa nacional de eliminação, uma vez que consegue delimitar áreas contíguas na região metropolitana do Recife com e sem transmissão filarial.