Environmental and Household-Based Spatial Risks for Tungiasis in an Endemic Area of Coastal Kenya

Abstract

Tungiasis is a cutaneous parasitosis caused by an embedded female sand flea. The distribution of cases can be spatially heterogeneous even in areas with similar risk profiles. This study assesses household and remotely sensed environmental factors that contribute to the geographic distribution of tungiasis cases in a rural area along the Southern Kenyan Coast. Data on household tungiasis case status, demographic and socioeconomic information, and geographic locations were recorded during regular survey activities of the Health and Demographic Surveillance System, mainly during 2011. Data were joined with other spatial data sources using latitude/longitude coordinates. Generalized additive models were used to predict and visualize spatial risks for tungiasis. The household-level prevalence of tungiasis was 3.4% (272/7925). There was a 1.1% (461/41,135) prevalence of infection among all participants. A significant spatial variability was observed in the unadjusted model (p-value < 0.001). The number of children per household, earthen floor, organic roof, elevation, aluminum content in the soil, and distance to the nearest animal reserve attenuated the odds ratios and partially explained the spatial variation of tungiasis. Spatial heterogeneity in tungiasis risk remained even after a factor adjustment. This suggests that there are possible unmeasured factors associated with the complex ecology of sand fleas that may contribute to the disease’s uneven distribution.

National prevalence and risk factors for tungiasis in Kenya

“…This is similar to another survey conducted in all households in the Kwale health and demographic surveillance system in 2011 [ 20 ], which found a prevalence of 1.1%. Other prevalence surveys that have been published to date report a wide range of prevalence from 7% in a village in coastal Kenya [ 12 ] to 63% in Napak district in northeastern Uganda [ 13 ].…”

Socio-ecological risk factors associated with human flea infestations of rural household in plague-endemic areas of Madagascar

“…Moreover, in larger households, diverse activities may increase flea exposure. Similar trends were observed in Ethiopia regarding tungiasis [43,44], and in Bogota regarding flea-induced skin disorder [42], indicating higher risks for children going to school, from larger families, and those using public transportation. Research in China suggests that floor fleas can transfer between houses, especially in larger villages [25].…”

“…The use of smoother flooring materials, such as board or concrete, may allow more thorough cleaning and may explain the protective effect demonstrated in our model. Indeed, studies involving other flea species mentioned earthen floor as one of the risk factors for the prevalence of flea infestations or flea-induced skin disorders [25,[42][43][44]. Flea immature stages are very susceptible to desiccation [2,45], and earthen floor covered with plant fiber mats may offer immature fleas the best conditions for survival.…”

Case Report: Severe Infestation with Tungiasis in a Coastal Community in Badagry Lagos, Nigeria.

“…The infestation cycle of the flea lasts for about a month and consists of an on-host and off-host phase (Nsanzimana et al, 2019). The female sand flea produces eggs after copulation and swells in size as the eggs develop thereby causing stress to the surrounding skin tissues (Hyuga et al, 2022). The appearance of the external site of the afflicted skin is characterized by a white papule or nodule with a central black dot at the onset of infection (Abarzua et al, 2014).…”

“…Several environmental, demographic, and behavioral factors have been associated with disease incidence. These include age groups, low socioeconomic status, lack of access to social amenities, illiteracy, low hygiene and poor health behaviors (Hyuga et al, 2022). Tunga species have been documented to thrive on dry sandy warm soil of deserts, beaches and close to farms, especially in rural areas.…”