A case study of risk factors for lymphatic filariasis in the Republic of Congo

Abstract

BackgroundLittle is known regarding risk factors for lymphatic filariasis (LF) in Central Africa. We studied the epidemiology of LF in an endemic village in the Republic of Congo.MethodsDependent variables were Wuchereria bancrofti antigenemia (ICT card test) and microfilaremia (night blood smears). The following factors were investigated: sex, age, bed net, latrines, source of water, uptake of anthelmintic drugs, hunting/fishing activities, and occasionally sleeping in the bush. Mixed multivariate logistic regression models were used.Results134 of 774 subjects aged ≥ 5 years (17.3%) had W. bancrofti antigenemia and 41 (5.3%) had microfilaremia (mf). Infection rates increased with age up to roughly 20 years and remained stable thereafter. Multivariate analysis of antigenemia demonstrated an increased risk for males (OR = 2.0 [1.3-3.0]) and for people who hunt or fish (OR = 1.5 [1.0-2.4]) and a protective effect of latrines (OR = 0.5 [0.4-0.8]). Among males, those hunting or fishing at night had an increased risk for antigenemia (OR = 1.9 [1.1-3.5]), and use of latrines was protective (OR = 0.5 [0.3-0.9]). For females, bed nets were protective (OR = 0.4 [0.1-0.9]), and there was a strong household effect (intraclass correlation coefficient [ICC]: 0.24). When mf was used as the dependent variable, males had a higher risk for infection (OR = 5.4 [2.1-13.4]), latrines had a protective effect (OR = 0.4 [0.1-0.9]) and there was a marked household effect (ICC = 0.49).ConclusionsAge, sex, and occupation-dependent exposure to mosquitoes were important risk factors for infection with W. bancrofti in this study. It is likely that men often acquire infection in high transmission areas outside of the village, while children and women are infected in areas with lower transmission inside or near the village. Additional studies are needed to determine whether these findings apply to other areas in Central Africa.

Impact of mass drug administration for elimination of lymphatic filariasis in Nepal

“…In contrast, four rural districts having high MDA coverage were unable to stop LF transmission after five MDA rounds; we noted that these districts’ baseline LF prevalence was comparatively higher. Thus, MDA coverage is not the single factor that may determine the number of MDA rounds required to interrupt LF transmission, and other factors such as baseline LF prevalence, population density [ 29 ], occupation [ 30 ], personal hygiene [ 31 ], level of education and nutritional status [ 2 ] should be considered. Overall, our study showed the effective implementation of LF elimination efforts in Nepal, with some districts requiring additional MDA rounds to achieve LF transmission interruption.…”

A call to action for universal health coverage: Why we need to address gender inequities in the neglected tropical diseases community

“…The division of labor within and beyond the household and everyday practices intersects with other determinants such as age and socioeconomic status to affect exposure to NTD risks. For example, in contexts such as the Republic of Congo (where fishing, farming, hunting are the main income activities), prevalence of lymphatic filariasis (LF) in men is higher, especially where men sleep outside during these activities [12]. However, where people have similar occupational activities, such as agricultural work (as found in rural India), LF infection patterns among men and women were almost equal [13].…”

Sex and Gender Differences in Infection and Treatments for Infectious Diseases

“…Hookworm infections, for example, appear to be more common in males (Behnke et al 2000;Pullan et al 2008) as is schistosomiasis (Pullan et al 2008). Filarial nematode infections show a higher prevalence in males (22.9 %) than females (12.6 %) in both rural (Chesnais et al 2014) and urban endemic regions (Mwakitalu et al 2014). Whether differences in the prevalence of nematode infections between men and women reflect differential host immunity, hormone levels, behavior, or a combination of factors must be empirically evaluated.…”