Strongyloides stercoralis: spatial distribution of a highly prevalent and ubiquitous soil-transmitted helminth in Cambodia

Abstract

14Background 15 Strongyloides stercoralis is a neglected soil-transmitted helminth that occurs worldwide and 16 can cause long-lasting and potentially fatal infections due to its ability to replicate within its 17 host. S. stercoralis causes gastrointestinal and dermatological morbidity. The objective of this 18 study was to assess the S. stercoralis infection risk, and using geostatistical models, to predict 19 its geographical distribution in Cambodia. 20 Methodology / Principal Findings 21A nation-wide community-based parasitological survey was conducted among the population 22 aged 6 years and above. S. stercoralis was diagnosed using a serological diagnostic test 23 detecting antigens in urine. Data on demography, hygiene and knowledge about helminth 24 infection were collected. S. stercoralis prevalence among 7,246 participants with complete 25 data record was 30.5% and ranged across provinces between 10.9% and 48.2%. The parasite 26 was ubiquitous in Cambodia, with prevalence rates below 20% only in five south-eastern 27 provinces. Infection risk increased with age both in men and women although girls aged less 28 than 13 years and women aged 50 years and above had lower odds of infection than their male 29 counterparts. Open defecation was associated with higher odds of infection while declaring 30 having some knowledge about health problems caused by worms was protective. Infection 31 risk was positively associated with night maximum temperature, minimum rainfall, and 32 distance to water, and negatively associated with land occupied by rice fields. 33 Conclusions / Significance 34 S. stercoralis infection is ubiquitous and rampant in Cambodia. The parasite needs to be 35 addressed by control programs delivering ivermectin. However the high cost of this drug in 36 Cambodia currently precludes control implementation. Donations, subsidization or the 3 37 production of affordable generic production are needed so S. stercoralis, which infests almost 38 a third of the Cambodian population, can be addressed by an adequate control program. 39 40 41 Authors Summary 42The threadworm, Strongyloides stercoralis, is a most neglected worm infection transmitted 43 through infective larvae on the soil. Threadworms occur worldwide and particularly in 44 tropical climates. It may cause long-lasting and potentially fatal infections due to its ability to 45 replicate within its host. This study aimed to assess the risk of threadworm infection in at the 46 national level in Cambodia. 47We conducted a nation-wide community-based parasitological survey among the population 48 aged 6 years and above. The threadworm was diagnosed using a serological diagnostic test 49 detecting antigens in urine. Data on demography, hygiene and knowledge about helminth 50 infection were collected. The threadworm infection risk was calculated by using geostatistical 51 models to predict its geographical distribution in Cambodia. About one third (30.5%) of the 52 enrolled study participants (n=7,246) were infected with threadworms. The lowest ...

Strongyloides stercoralis prevalence and diagnostics in Vientiane, Lao People’s Democratic Republic

“…Studies on S. stercoralis epidemiology from Southeast Asia indicate that S. stercoralis infection are predominately found in men, that the infection increases with age and that rural populations have a higher risk for infection [ 7 , 8 , 10 , 14 ]. Our S. stercoralis patients follow these typical risk patterns although they have been recruited from a health services and not as the previous indicated studies from the community.…”

“…In recent effort to model global S. stercoralis prevalence, an S. stercoralis infection prevalence between 10 and 15% has been estimated in Southeast Asian countries [ 2 ]. But a nation-wide survey in Cambodia detected a overall prevalence of 30.5% in the rural population [ 8 ].…”

Prevalence and risk factors of strongyloidiasis among schoolchildren in Sabach Sanjal and Upper Badibou districts in the North Bank East Region of The Gambia

“…However, in this study, the detection of S. stercoralis larvae is part of a bigger schistosomiasis and STHs mapping which uses an AFRO questionnaire capturing data on schistosomiasis and STHs, thus the environmental variables and other potential risk factors for S. stercoralis such as walking barefooted, open defaecation, playing without shoes and eating fruits and vegetables that are not well washed within the two districts' school climate were not evaluated. Previous studies have reported that S. stercoralis infection is correlated with temperature, rainfall, open defaecation, inadequate portable water, farming, walking barefooted, playing without shoes, consuming fruits and vegetables which are not well washed ( Zeehaida et al, 2011 ; Kola et al, 2013 ; CDC, 2013 ; Beknazarova et al, 2016 ; Forrer et al, 2019 ). Differences between the two districts in socioeconomic demography, environmental factors and children's activities may explain our observations.…”

Progress towards the implementation of control programmes for strongyloidiasis in endemic areas: estimation of number of adults in need of ivermectin for strongyloidiasis

“…One main reason for this is the higher prevalence of infection in adults than children, owing to chronic infection, persisting indefinitely if not treated, as the consequence of the peculiar auto-infective cycle of the parasite. Although studies reporting data on age distribution of strongyloidiasis are scant [4][5][6][7][8], the higher prevalence in adults is biologically plausible, since in older ages we have a cumulative rate of strongyloidiasis owing to chronic and new infections that occur over time.…”