This study identified a very high prevalence of scabies and impetigo among children in Timor-Leste. Weighted prevalence of scabies (30.6%) was higher than in previous large-scale surveys, including a 2016 school survey in Dili and Ermera (22.4%)7 and a 2007 survey of schools, clinics and hospitals of Oe-Cusse, Bobonaro, Cova Lima and Dili (17.3%)8. Weighted prevalence of impetigo (11.3%) was also higher than in two surveys (9.7%7; 6.6%8).
Changes to our Dili sample population compared to the 2016 study may explain increases in the overall scabies prevalence. Scabies prevalence in Dili (28.2%) was markedly higher than recently reported (26/502, 5.2%)7, however Ermera (30.3%) and Manufahi (53.6%) were comparable to previous findings in 2016 (286/894, 32.0%)7 and 1970 (181/295, 61.3%)9, respectively. In Dili, we surveyed two semi-urban primary schools outside the capital city while the only Dili school included in the 2016 study was in the urban city. This semi-urban population may in fact be more representative of rural settings, where our findings suggest children are at higher risk of scabies and impetigo than in urban settings. Migration during Holy Week and Easter celebrations may have led to overestimates in our Dili results. Families with scabies in Dili may be less inclined to travel, or rural residents attending the city may have increased communicable skin disease exposure, or city-dwelling children visiting endemic rural regions may have returned infested with the mite.
Rural scabies prevalence was among the highest reported globally, and comparable to rates reported in Fiji (32%)20 and northern Australia (35%)21, but fewer than a small sample in Papua New Guinea (78%)22.5 Children in Manufahi, the most remote municipality sampled, were more likely to have scabies and impetigo than in Dili. Participants in Manufahi and Ermera had nearly twice the odds of impetigo infection than children in Dili. Risk factors for scabies, including poverty, household crowding, and poor access to healthcare, are more likely to predominate in less urban populations.19,23 Considering that over two-thirds of the national population reside in mountainous rural areas with limited access to health services similar to Ermera and Manufahi,6 our results suggest scabies may be a significant national child health problem. Moreover, availability of first-line scabicidal therapy, including topical permethrin and benzyl benzoate, is limited in Timor-Leste. Community management strategies are urgently required, with particular attention to at-risk rural populations. The impact of ivermectin, diethylcarbamazine citrate and albendazole MDA for lymphatic filariasis on scabies and impetigo has not been studied elsewhere. This survey will serve as baseline to assess change in prevalence of the skin conditions after the MDA program.
We identified a strong association between scabies infestation and impetigo infection. In our study, the PAR of impetigo because of scabies (22.7%) was less than values reported in the Pacific region, such as Solomon Islands (41.1%)18. Secondary bacterial infection of scabies lesions with group A streptococci has been implicated in post-infective glomerulonephritis, rheumatic fever and RHD.4 While the attributable risk of scabies for these complications of impetigo is not currently known,10 Timor-Leste has among the highest globally reported rates of RHD.24 Comprehensive control strategies for impetigo require national attention. Availability of impetigo treatment options, including intramuscular benzathine penicillin G and oral amoxycillin, are improving with limited stockouts nationally. Individual treatment is useful for reduction of impetigo in highly endemic regions,25 and should be available alongside investment in water, sanitation and hygiene programs, and community education.
Our study identified 10 to 14 year old adolescents were less likely to have scabies than 5 to 9 year old children, in keeping with observed epidemiology globally.5 Although our focus was school-aged children, scabies prevalence was very high in a small sample of 0 to 4 year olds (13/25, 52.0%). There may have been overestimation of prevalence in infants if families were more inclined to attend the survey with young children who they considered had skin conditions requiring medical attention.
We used a training and diagnostic method, the 2020 IACS criteria14, novel to Timor-Leste but widely used in Pacific island settings. In sites where this approach has been used, non-expert examiners, including clinical officers and nurses, who underwent brief training similar to our study diagnosed less scabies but with high specificity compared to consensus expert opinion.17,26 The approach is a valid tool for scabies diagnosis in population-level research, although additional studies are required to validate the criteria’s diagnostic accuracy.17
There were limitations to our study. We were unable to include children absent from school on survey days, which may have underestimated the burden of disease and missed cases of crusted scabies, which frequently precludes school attendance.27 Participant numbers were lower than the number of students enrolled, due to low student attendance around the Easter holiday period. Not all registered children underwent skin examination. Competing school priorities for students and, on occasion, a high number of children relative to research staff meant participants were not always examined on the same day as registration, which led to missed examinations where children did not return to school the subsequent day. Examination was limited to visible skin which may have contributed to underdiagnosis of skin conditions, and underestimates of severity, but this was most appropriate for privacy and cross-sectional study. Confirmation of clinical and suspected scabies diagnoses with direct observation of the mite or its products by dermoscopy, skin scrapings and microscopy was not used as this was a pragmatic field survey and these tools are usually not available in clinical practice.