Prevalence, intensity and associated risk factors of soil-transmitted helminth and schistosome infections in Kenya: Impact assessment after five rounds of mass drug administration in Kenya

Helminthiasis and malaria co-infection among women of reproductive age in a rural setting of Kilifi County, coastal Kenya: A mixed method study

Soil transmitted helminthiasis (STH), Schistosoma haematobium and malaria co-infection lead to increased susceptibility to other infections and poor pregnancy outcomes among women of reproductive age (WRA). This study sought to establish risk factors, burden of co-infection with STH, S. haematobium and Plasmodium sp. among WRA in Kilifi County, Kenya.A mixed method cross-sectional study was conducted on 474 WRA in 2021. Simple random sampling was used to select WRA from four villages in two purposively sampled sub-counties. Study participants were interviewed, and stool samples collected and analysed using Kato-Katz technique for STH. Urine samples were collected for examination of S. haematobium while malaria microscopic test was done using finger prick blood samples. Further, 15 focus group discussions (FGDs) were conducted with purposively selected WRA and qualitative data analyzed thematically using Nvivo software. Quantitative and qualitative methods were triangulated to comprehensively strengthen the study findings. Prevalence of S. haematobium was 22.3% (95%CI: 13.5-36.9), any STH 5.2% (95%CI: 1.9-14.3) and malaria 8.3% (95%: 3.8-18.2). Co-infections between any STH and S. haematobium was 0.8% (95%CI: 0.2-3.2) and between S. haematobium and malaria 0.8% (95%CI: 0.2-3.1). Multivariable analysis showed increased odds of any STH infections among participants in Rabai Sub-County, (aOR = 9.74; p = 0.026), businesswomen (aOR = 5.25; p<0.001), housewives (aOR = 2.78; p = 0.003), and casual laborers (aOR = 27.03; p<0.001). Qualitative analysis showed that the three parasitic diseases were common and responsible for possible causes of low birth weight, susceptibility to other infections and complications such as infertility and cancer later in life.The study demonstrated that STH, S. haematobium and malaria are still a public health problem to WRA. Some of the associated risks of infection were geographical location, socio-economic and WASH factors. Hence the need to implement integrated control efforts of the three parasitic infection.

Evaluation of copromicroscopy, multiplex-qPCR and antibody serology for monitoring of human ascariasis in endemic settings

BACKGROUND

The standard diagnosis of Ascaris lumbricoides and other soil-transmitted helminth (STH) infections relies on the detection of worm eggs by copromicroscopy. However, this method is dependent on worm patency and shows only limited accuracy in low-intensity infection settings. We aimed to decipher the diagnostic accuracy of different antibodies using various Ascaris antigens in reference to copromicroscopy and quantitative PCR (qPCR), four months after national STH preventative chemotherapy among school children in western Kenya.

METHODOLOGY

STH infection status of 390 school children was evaluated via copromicroscopy (Kato-Katz and mini-FLOTAC) and qPCR. In parallel, Ascaris-specific antibody profiles against larval and adult worm lysates, and adult worm excretory-secretory (ES) products were determined by enzyme-linked immunosorbent assay. Antibody cross-reactivity was evaluated using the closely related zoonotic roundworm species Toxocara cati and Toxocara canis. The diagnostic accuracy of each antibody was evaluated using receiver operating curve analysis and the correspondent area under the curve (AUC).

PRINCIPAL FINDINGS

Ascaris was the predominant helminth infection with an overall prevalence of 14.9% (58/390). The sensitivity of mini-FLOTAC and Kato-Katz for Ascaris diagnosis reached only 53.5% and 63.8%, respectively compared to qPCR. Although being more sensitive, qPCR values correlated with microscopic egg counts (R = -0.71, P<0.001), in contrast to antibody levels. Strikingly, IgG antibodies recognizing the ES products of adult Ascaris worms reliably diagnosed active Ascaris infection as determined by qPCR and microscopy, with IgG1 displaying the highest accuracy (AUC = 0.83, 95% CI: 0.75-0.91).

CONCLUSION

IgG1 antibody responses against adult Ascaris-ES products hold a promising potential for complementing the standard fecal and molecular techniques employed for monitoring Ascaris infections. This is of particular importance in the context of deworming programs as the antibody diagnostic accuracy was independent of egg counts.

Pattern and predictor of hookworm re-infection among schoolchildren in three districts of Amhara Region, northwest Ethiopia

BACKGROUND

Despite integrated prevention and control measures, the prevalence of hookworm is still high in Ethiopia. The re-infection rates and predictors are poorly addressed. Therefore, this study aimed to determine the patterns of hookworm re-infection rates and predictors among schoolchildren in northwest Ethiopia.

METHODS

A prospective follow-up study was conducted among 86 schoolchildren from May to December 2022. Data on predictors was collected using a questionnaire. Stool samples were collected and processed via Kato-Katz, McMaster, and spontaneous tube sedimentation techniques. All hookworm-infected children were treated with albendazole and followed for six months. The re-infection rates of hookworm were checked in the 4th and 6th months. Data was entered into Epi-data version 3.1 and analysed using SPSS version 25. Descriptive statistics were used to compute the re-infection rate. The associations of predictors with hookworm re-infection rates were calculated by logistic regression. Variables with a p-value < 0.05 were considered statistically significant.

RESULTS

Of the 86, 81 schoolchildren completed the study. The prevalence of hookworm re-infection in the 4th and 6th months was 23.5% and 33.3%, respectively. Living with family members greater than five (p = .017), poor utilization of latrine (p = .008), infrequent shoe wear (p = .039), and participating in irrigation (p = .020) were the predictors significantly associated with hookworm re-infections.

CONCLUSIONS

The re-infection rate was high during the fourth and sixth months. Participating in irrigation, infrequent shoe wear, and poor latrine utilization were predictors of hookworm re-infection. Therefore, mass drug administration, regular shoe wearing, and health education should be advocated.

Optimal control analysis of a transmission interruption model for the soil-transmitted helminth infections in Kenya

Kenya is among the countries endemic for soil-transmitted helminthiasis (STH) with over 66 subcounties and over 6 million individuals being at-risk of infection. Currently, the country is implementing mass drug administration (MDA) to all the at-risk groups as the mainstay control strategy. This study aimed to develop and analyze an optimal control (OC) model, from a transmission interruption model, to obtain an optimal control strategy from a mix of three strategies evaluated. The study used the Pontryagin's maximum principle to solve, numerically, the OC model. The analysis results clearly demonstrated that water and sanitation when implemented together with the MDA programme offer the best chances of eliminating these tenacious and damaging parasites. Thus, we advocate for optimal implementation of the combined mix of the two interventions in order to achieve STH elimination in Kenya, and globally, in a short implementation period of less than eight years.

Spatial variation and clustering of anaemia prevalence in school-aged children in Western Kenya

Anaemia surveillance has overlooked school-aged children (SAC), hence information on this age group is scarce. This study examined the spatial variation of anaemia prevalence among SAC (5-14 years) in western Kenya, a region associated with high malaria infection rates. A total of 8051 SAC were examined from 82 schools across eight counties in Western Kenya in February 2022. Haemoglobin (Hb) concentrations were assessed at the school and village level and anaemia defined as Hb<11.5g/dl for age 5-11yrs and Hb <12.0g/dl for 12-14yrs after adjusting for altitude. Moran's I analysis was used to measure spatial autocorrelation, and local clusters of anaemia were mapped using spatial scan statistics and local indices of spatial association (LISA). The prevalence of anaemia among SAC was 27.8%. The spatial variation of anaemia was non-random, with Global Moran's I 0.2 (p-value < 0.002). Two significant anaemia cluster windows were identified: Cluster 1 (LLR = 38.9, RR = 1.4, prevalence = 32.0%) and cluster 2 (LLR = 23.6, RR = 1.6, prevalence = 45.5%) at schools and cluster 1 (LLR = 41.3, RR = 1.4, prevalence = 33.3%) and cluster 2 (LLR = 24.5, RR = 1.6, prevalence = 36.8%) at villages. Additionally, LISA analysis identified ten school catchments as anaemia hotspots corresponding geographically to SatScan clusters. Anaemia in the SAC is a public health problem in the Western region of Kenya with some localised areas presenting greater risk relative to others. Increasing coverage of interventions, geographically targeting the prevention of anaemia in the SAC, including malaria, is required to alleviate the burden among children attending school in Western Kenya.

Model-based geostatistical design and analysis of prevalence for soil-transmitted helminths in Kenya: Results from ten-years of the Kenya national school-based deworming programme

Background

Kenya is endemic for soil-transmitted helminths (STH) with over 6 million children in 27 counties currently at-risk. A national school-based deworming programme (NSBDP) was launched in 2012 with a goal to eliminate parasitic worms as a public health problem. This study used model-based geostatistical (MBG) approach to design and analyse the impact of the NSBDP and inform treatment strategy changes.

Methods

A cross-sectional study was used to survey 200 schools across 27 counties in Kenya. The study design, school selection and analysis followed the MBG approach which incorporated historical data on treatment, morbidity and environmental covariates to efficiently predict the helminths prevalence in Kenya.

Results

Overall, the NSBDP geographic area prevalence for any STH was estimated to sit between 2 % and <10 % with a high predictive probability of >0.999. Species-specific thresholds were between 2 % and <10 % for Ascaris lumbricoides, 0 % to <2 % for hookworm, and 0 % to <2 % for Trichuris trichiura, all with high predictive probability of >0.999.

Conclusions

Based on the World Health Organization guidelines, STH treatment requirements can now be confidently refined. Ten counties may consider suspending treatment and implement appropriate surveillance system, while another 10 will require treatment once every two years, and the remaining seven will require treatment once every year.

The impact of dual- versus single-dosing and fatty food co-administration on albendazole efficacy against hookworm among children in Mayuge district, Uganda: Results from a 2x2 factorial randomised controlled trial

BACKGROUND

Mass Drug Administration (MDA) is the main strategy for control of soil-transmitted helminth (STH) infections, with single-dose benzimidazole (albendazole or mebendazole) the principal MDA option. In Mayuge district, Uganda, an MDA programme has been in place for over fifteen years but hookworm infection remains common and there is concern that the effectiveness of single-dose albendazole as currently used for MDA may be sub-optimal. This study aims to assess the efficacy of dual- versus single-dose albendazole, with and without fatty food co-administration against hookworm, the dominant form of STHs in Mayuge district, Uganda.

METHODOLOGY

This was a 2x2 factorial randomised controlled trial to investigate two interventions simultaneously; 1) dual-dose versus single-dose albendazole, 2) taking albendazole with or without fatty food (200 grams of avocado eaten directly after medication). School children with hookworm infection were randomised in a 1:1:1:1 ratio to the four possible treatment groups. Three weeks after the treatment, stool samples were collected from trial participants to evaluate trial outcomes: cure rate and egg reduction rate (ERR).

PRINCIPAL FINDINGS

A total of 225 participants were enrolled, and 222 (98.7%) seen at 3 weeks. The cure rate in the dual-dose group was 96.4% (95% CI: 90.9-99%), higher than 83.9% (95% CI: 75.7-90.2%) in the single-dose group (OR: 5.07, 95% CI:1.61-15.96, p = 0.002). The ERR was 97.6% and 94.5% in the dual-dose group and single-dose drug group, respectively (ERR difference 3.1%, 95% CI: -3.89-16.39%, p = 0.553). The cure rates among participants taking albendazole with and without avocado were 90.1% and 89.1%, respectively, with no statistical difference between the two groups (OR: 1.24, 95% CI: 0.51-3.03, p = 0.622). The ERR was 97.0% and 94.2% in the group receiving albendazole with and without avocado, respectively, and the difference in ERR between the two groups was 2.8% (95% CI -8.63-14.3%, p = 0.629).

CONCLUSIONS/SIGNIFICANCE

In Ugandan school children, dual-dose albendazole improves the cure rate of hookworm compared to single-dose albendazole. However, there was no significant improvement in cure rate or egg reduction rate of hookworm with fatty-food co-administration. Dual-dose albendazole is a feasible alternative for improving drug effectiveness against hookworm infection and minimising drug resistance.

TRIAL REGISTRATION

PACTR202202738940158.

Soil-transmitted helminthiasis in mainland China from 2016 to 2020: a population-based study

Background

Soil-transmitted helminthiasis is epidemic in China and many other countries of the world, and has caused substantial burdens to human health. We conducted successive national monitoring in China from 2016 to 2020 to analyze the prevalence, changing trends, and factors influencing soil-transmitted helminthiasis, which provided a reference for future control strategies.

Methods

Soil-transmitted helminth monitoring was carried out in 31 provinces (autonomous regions or municipalities, herein after referred to as "provinces") throughout China. Each province determined the number and location of monitoring sites (counties), and a unified sampling method was employed. At least 1,000 subjects were investigated in each monitoring county. Stool samples were collected and the modified Kato-Katz thick smear method was employed for stool examination. Infection data and the details of factors influencing soil-transmitted helminthiasis from 2016 to 2020 were collected from national monitoring sites. Additional influencing factors such as environment, climate and human activities were obtained from authoritative websites. Prevalence of soil-transmitted helminths was presented by species, province, sex, and age group. ArcGIS software was used to conduct spatial autocorrelation and hotspot analysis on the infection data. A Poisson distribution model and SaTScan software were used to analyze the infection data with retrospective spatiotemporal scan statistics. A database was built by matching village-level infection rate data with influencing factors. Subsequently, machine learning methods, including a Linear Regression (LR), a Random Forest (RF), a Gradient Boosted Machine (GBM), and an Extreme gradient boosting (XGBOOST) model was applied to construct a model to analyze the main influencing factors of soil-transmitted helminthiasis.

Findings

The infection rates of soil-transmitted helminths at national monitoring sites from 2016 to 2020 were 2.46% (6,456/262,380), 1.78% (5,293/297,078), 1.29% (4,200/326,207), 1.40% (5,959/424,766), and 0.84% (3,485/415,672), respectively. The infection rate of soil-transmitted helminths in 2020 decreased by 65.85% compared to that in 2016. From 2016 to 2020, the infection rate of soil-transmitted helminthiasis was relatively high in southern and southwestern China, including Hainan, Yunnan, Sichuan, Guizhou, and Chongqing. In general, the infection rate was higher in females than in males, with the highest rate in the population aged 60 years and above, and the lowest in children aged 0-6 years. Global autocorrelation and hotspot analyses revealed spatial aggregation in both the national and local distribution of soil-transmitted helminthiasis in China from 2016 to 2020. The hotspots were concentrated in southwestern China. The spatiotemporal scanning analysis revealed aggregation years from 2016 to 2017 located in southwestern China, including Yunnan, Sichuan, Chongqing, Guizhou and Guangxi. The RF model was the best fit model for the infection rate of soil-transmitted helminths in China. The top six influencing factors of this disease in the model were landform, barefoot farming, isothermality, temperature seasonality, year, and the coverage of sanitary toilets.

Interpretation

The overall infection rate of soil-transmitted helminths in China showed a decreasing trend from 2016-2020 due to the implementation of control measures and the economic boom in China. However, there are still areas with high infection rates and the distribution of such areas exhibit spatiotemporal aggregation. As a strategic next step, control measures should be adjusted to local conditions based on the main influencing factors and the prevalence of different sites to aid in the control and elimination of soil-transmitted helminthiasis.

Funding

This research was funded by the National Key Research and Development Program of China (Grant Nos. 2021YFC2300800 and 2021YFC2300804) and the National Natural Science Foundation of China (Grant No. 32161143036).

School-based preventive chemotherapy program for schistosomiasis and soil-transmitted helminth control in Angola: 6-year impact assessment

BACKGROUND

A school preventive chemotherapy (PC) program for soil-transmitted helminths (STHs) and schistosomiasis has operated in Huambo, Uige and Zaire provinces, Angola, since 2013 and 2014, respectively; complemented by a school water, sanitation and hygiene (WASH) program in a subset of schools from 2016. Conducted in 2021, this is the first impact assessment of the school program for the control of schistosomiasis and STHs.

METHODOLOGY/PRINCIPAL FINDINGS

A two-stage cluster design was used to select schools and schoolchildren for parasitological and WASH surveys. The rapid diagnostic tests (RDTs), point of care circulating cathodic antigen (POC-CCA) and Hemastix, were used to estimate Schistosoma mansoni and Schistosoma haematobium prevalence, respectively. Kato Katz was used to detect STHs, and quantify STH and S. mansoni infections. Urine filtration was used to quantify S. haematobium infections. Prevalence, infection intensity, relative prevalence reduction and egg reduction rates were calculated for schistosomiasis and STHs. Cohen's Kappa co-efficient was used to assess agreement between RDTs and microscopy. Chi-square or Fisher's exact test was used to compare WASH indicators in WASH-supported and WASH-unsupported schools. Overall, 17,880 schoolchildren (599 schools) and 6,461 schoolchildren (214 schools) participated in the schistosomiasis and STH surveys, respectively. Prevalence of any schistosomiasis in Huambo was 29.6%, Uige 35.4%, and Zaire 28.2%. Relative reduction in schistosomiasis prevalence from 2014 for Huambo was 18.8% (95% confidence interval (CI) 8.6, 29.0), Uige -92.3% (95%CI -162.2, -58.3), and Zaire -14.0% (95%CI -48.6, 20.6). Prevalence of any STH in Huambo was 16.3%, Uige 65.1%, and Zaire 28.2%. Relative reduction in STH prevalence for Huambo was -28.4% (95%CI -92.1, 35.2), Uige -10.7% (95%CI -30.2, 8.8), and Zaire -20.9% (95%CI -79.5, 37.8). A higher proportion of WASH-supported schools had improved water sources, and toilet and handwashing facilities compared to WASH-unsupported schools.

CONCLUSIONS/SIGNIFICANCE

The limited impact this school program has had in controlling schistosomiasis and STHs identifies the need for a comprehensive understanding of individual, community, and environmental factors associated with transmission, and consideration for a community-wide control program.

Understanding factors responsible for the slow decline of soil-transmitted helminthiasis following seven rounds of annual mass drug administration (2012-2018) among school children in endemic counties of Kenya: A mixed method study

BACKGROUND

Soil-transmitted helminthiasis (STH) continue to be a significant health problem in Sub-Saharan Africa especially among school children. In Kenya, treatment of over five million children has been conducted annually in 28 endemic counties since the year 2012. However, the latest monitoring and evaluation (M&E) results indicated a slow decline of prevalence and intensity of STH in some counties after the seven rounds of annual mass drug administration (MDA). The current study sought to determine the factors associated with the slow decline in prevalence and intensity of STH among school children participating in the school deworming programme.

METHODOLOGY

Mixed methods cross-sectional study was conducted in three endemic counties of Kenya. For quantitative technique, simple random sampling was used to select 1,874 school children from six purposively selected primary schools. The school children were interviewed, and a single stool collected and analysed using Kato-Katz technique. While for qualitative methods, 15 focus group discussions (FGDs) were conducted with purposively selected parents/guardians of school children. Data was collected through voice records using FGD and analyzed using NVIVO.

FINDINGS

Prevalence of any STH infection was 30.8% (95%CI: 28.7-32.9), with the highest prevalence observed in Vihiga County (40.7%; 95%CI: 37.4-44.4). Multivariable analysis revealed that geographical location (OR = 3.78, (95%CI: 1.81-7.88) p<0.001), and not washing hands after defecation (OR = 1.91, (95%CI: 1.13-3.20) p = 0.015) were significantly associated with any STH infection. For qualitative analysis, majority of the parents/guardians of SAC felt that poor water sanitation and hygiene practices (WASH) both in school and household level could be a cause of continued STH infection. Also failing to include the rest of the community members in the MDAs were mentioned as possible contributors to observed slow decline of STH.

CONCLUSIONS

There was moderate STH prevalence and mean intensity despite the seven rounds of repeated annual MDA. The study recommends a revamped awareness creation on WASH and community wide treatment.

The Impact of Targeted Treatment and Mass Drug Administration Delivery Strategies on the Prevalence and Intensity of Schistosomiasis in School Aged Children in Africa: A Systematic Review

Schistosomiasis is a public health problem in more than 78 countries in the world. The disease is most prevalent among children than adults due to their high exposure to infectious water sources. Various interventions such as mass drug administration (MDA), snail control, safe water provision and health education have been implemented independently or jointly to control, reduce and ultimately eliminate Schistosomiasis. This scoping review focused on studies reporting the impact of different delivery strategies of targeted treatment and MDA on the prevalence and intensity of schistosomiasis infection in school aged children in Africa. The review focused on Schistosoma haematobium and Schistosoma mansoni species. A systematic search for eligible literature from peer-reviewed articles was done from Google Scholar, Medline, PubMed and EBSCO host databases. The search yielded twenty-seven peer-reviewed articles. All articles found reported a decrease in the prevalence of schistosomiasis infection. Five studies (18.5%) reported a prevalence change below 40%, eighteen studies (66.7%) reported a change between 40% and 80%, and four studies (14.8%) reported a change above 80%. The infection intensity post-treatment was varied: twenty-four studies reported a decrease, while two studies reported an increase. The review showed that the impact of targeted treatment on the prevalence and intensity of schistosomiasis depended on the frequency at which it was offered, complementary interventions, and its uptake by the target population. Targeted treatment can significantly control the infection burden, but cannot eliminate the disease. Constant MDA programs coupled with preventative and health promotional programs are required to reach the elimination stage.

Prevalence and Associated Risk Factors of Soil-Transmitted Helminth Infections among Schoolchildren around Lake Tana, Northwest Ethiopia

Background

Soil-transmitted helminths (STHs) are among the most common neglected tropical diseases widely distributed in tropical countries with poor socioeconomic development. Ascaris lumbricoides, Trichuris trichiura, and hookworm are the three major STHs. This study aimed to determine the prevalence of STHs and associated risk factors among schoolchildren in selected primary schools around Lake Tana, Northwestern Ethiopia.

Methods

A school-based cross-sectional study was conducted from February to May 2021 involving 337 study participants. A systematic random sampling method was utilized to select the study participants from the selected schools. Data related to sociodemographic characteristics of the study participants and risk factors for STH infections were collected using a pretested questionnaire. Stool samples were collected in sterile plastic containers from each participant and processed using Kato-Katz thick fecal smear and Ritchie's concentration techniques. The data were analyzed using the Statistical Package for Social Sciences software tool version 23, and factors with a p < 0.05 were considered as statistically significant.

Results

The overall prevalence of STH infection was 38.3% (95% CI: 33.1-43.7). Hookworm infection was the predominant STH infection, which was detected in 26.1% schoolchildren followed by A. lumbricoides (14.8%) and T. trichiura (1.5%). Most of the study subjects (34.1%) had single infections, whereas only 4.2% study subjects had multiple helminthic infections. Among the risk factors considered in the study, lack of shoe wearing habit (adjusted odds ratio [AOR]=29.5; 95% confidence interval [CI]=6.59-132.55; p < 0.001), lack of knowledge on the prevention and control methods (AOR = 5.41; 95% CI = 2.44-11.98; p < 0.001), engagement in irrigation activities (AOR = 2.14; 95% CI = 1.02-4.57, p = 0.049), lack of toilet (AOR = 3.06; 95% CI = 1.31-7.16; p = 0.01), children grades of 5-8 (AOR = 2.62; 95% CI = 1.26-5.43; p = 0.01), playing on soils (AOR = 5.90; 95% CI = 2.79-12.49; p < 0.001), lack of fingernail trimming habit (AOR = 3.21; 95% CI = 1.57-6.55; p = 0.001), and male gender (AOR = 2.28; 95% CI: 1.19-4.39; p = 0.013) were significant explanatory factors for STH infection among schoolchildren in the study area.

Conclusions

The present study showed that STHs were common among schoolchildren around Lake Tana. Therefore, education on personal and environmental hygiene should be taken into account to reduce the prevalence of STH infection in the study area.

The efficacy of soap against schistosome cercariae: A systematic review

BACKGROUND

Schistosomiasis is a parasitic disease that is endemic in 78 countries and affects almost 240 million people worldwide. It has been acknowledged that an integrated approach that goes beyond drug treatment is needed to achieve control and eventual elimination of the disease. Improving hygiene has been encouraged by World Health Organisation, and one aspect of good hygiene is using soap during water-contact activities, such as bathing and doing laundry. This hygiene practice might directly reduce the skin exposure to cercariae at transmission sites. A systematic review was carried out to investigate the efficacy of soap against schistosome cercariae and to identify the knowledge gaps surrounding this topic.

METHODOLOGY

Six online databases were searched between 5th and 8th July of 2021. Records returned from these databases were screened to remove duplicates, and the remaining records were classified by reading titles, abstracts, and full texts to identify the included studies. The results were categorised into two groups based on two different protective mechanisms of soap (namely, damage to cercariae and protection of skin).

CONCLUSIONS

Limited research has been conducted on the efficacy of soap against schistosome cercariae and only 11 studies met the criteria to be included in this review. The review demonstrates that soap has the potential of protecting people against schistosome cercariae and there are two protective aspects: (1) soap affects cercariae adversely; (2) soap on the skin prevents cercariae from penetrating the skin, developing into adult worms and producing eggs. Both aspects of protection were influenced by many factors, but the differences in the reported experimental conditions, such as the cercarial endpoint measurement used and the cercaria numbers used per water sample, lead to low comparability between the previous studies. This review indicates that more evidence is needed to inform hygiene advice for people living in schistosomiasis endemic areas.

Fine mapping of Ascaris lumbricoides, Trichuris trichiura and hookworm infections in sub-districts of Makenene in Centre Region of Cameroun

Preventive chemotherapy (PC) that remains the main control strategy recommended by the World Health Organization to achieve the elimination of soil-transmitted helminth (STH) infections as a public health problem must be strengthened by identifying the remaining transmission hot-spots for the deployment of appropriate control measures. This study was designed to assess the prevalence and infections intensities of soil-transmitted helminths and perform micro scale mapping in order to identify transmission hot-spots for targeted control operations. Stool samples were collected from 1775 children in ten primary schools of eight sub-districts of Makenene in Cameroon. Kato Katz technique was used to process and examine stool samples to detect the eggs of soil-transmitted nematodes. The prevalence of soil-transmitted helminth species as well as the infection intensities was compared. Data visualizations in forms of maps were made using Quantum geographic information system (QGIS) software. The overall prevalence of soil-transmitted helminth infections was 4.8% with a 95% confidence interval (CI) of 3.8–5.9%: 3.0% (95% CI 2.2–3.9) for Ascaris lumbricoides, 1.4% (95% CI 0.9–2.0) for Trichuris trichiura and 0.8% (95% CI 0.5–1.4) for hookworms. The prevalence of soil-transmitted helminth species differ significantly between schools and sub-districts. The intensity of infections was light (2.4%, 1.1% and 0.8%), moderate (0.4%, 0.1% and 0.1%) and heavy (0.2%, 0.2% and 0%) for A. lumbricoides, T. trichiura and hookworm respectively. The mean intensity of infections was 7255 EPG for A. lumbricoides, 2900 EPG for T. trichiura and 298 EPG for hookworm. Between schools, significant difference was recorded in the means of infection intensities of T. Trichiura and hookworms but not for A. lumbricoides. This difference was also significant for T. Trichiura when comparison were between sex. No significant difference were recorded when the comparison were between age. Fine mapping revealed that children harbouring heavy infections were clustered in the same sub-districts; highlighting the presence of high endemicity sub-districts and hot-spots for the transmission of different soil-transmitted helminth species. This study showed a diversity in the prevalence and transmission of different soil-transmitted helminth species. It also hightlighted the need for micro scale mapping to enable the localisation of high endemicity sub-districts and transmission hot-spot sites where targeted control operations must be deployed to achieve STH elimination.

Development of allele-specific PCR methodology (AS-PCR) to screening A. lumbricoides and A. suum

Ascaris lumbricoides and Ascaris suum are described as helminths that infect humans and pigs, respectively. It is estimated that infection by A. lumbricoides affects about 447 million individuals living in tropical regions of developing countries. However, there is an increasing number of cases of human ascariasis in countries with no recent history of autochthonous infection by A. lumbricoides. In these places, pigs have been incriminated as the main source of human infection. Conventional parasitological diagnosis does not allow species-specific identification, and the real epidemiological scenario of human and swine ascariasis is still uncertain. Therefore, this work presents the application of a species-specific molecular diagnosis, based on the allele-specific PCR methodology (AS-PCR), using the Internal Transcript Space 1 (ITS-1) of the ribosomal DNA, as a target for differentiating between the two species, using DNA obtained from eggs. To validate the methodology, stool samples positive for Ascaris spp, were obtained from 68 humans from seven Brazilian states and from six pigs from the state of Minas Gerais. All samples obtained from humans were genotyped as A. lumbricoides and all samples obtained from swine were genotyped as A. suum. These results are in agreement with the literature, which demonstrates that in most endemic regions, transmission cycles are separate. Therefore, the execution of this work allowed the availability of a useful methodology for the differential diagnosis of the species, which may contribute to the characterization of the real epidemiological profile of human and swine ascariasis, and to the implementation of future control strategies.

Urude R, Kadimbo J, Danboyi J, Miri E, Nute AW, Rakers L, Nebe O, Anyaike C, Weiss P, S. Noland G, Richards F. Impact of Three to Five Rounds of Mass Drug Administration on Schistosomiasis and Soil-Transmitted Helminths in School-Aged Children in North-Central Nigeria

Nasarawa and Plateau states of north-central Nigeria have implemented programs to control schistosomiasis (SCH) and soil-transmitted helminths (STH) in children since the 1990s. Statewide mapping surveys were conducted in 2013, when 11,332 school-aged children were sampled from 226 schools. The local government areas (LGAs) then received varying combinations of mass drug administration (MDA) for the next 5 years. We revisited 196 (87%) schools in 2018 plus an additional six (202 schools in total), sampling 9,660 children. We calculated overall prevalence and intensity of infection and evaluated associations with gender; age; behaviors; water, sanitation, and hygiene (WASH); and treatment regimen. Urine heme detection dipsticks were used for Schistosoma hematobium in both surveys, with egg counts added in 2018. Stool samples were examined by Kato-Katz for Ascaris lumbricoides, Trichuris trichiura, Schistosoma mansoni, and hookworm. Schistosomiasis prevalence among sampled students dropped from 12.9% (95% confidence interval [CI]: 11.1-14.9%) to 9.0% (95% CI: 7.5-10.9%), a statistically significant change (P < 0.05). In 2018, eight LGAs still had > 1% of children with heavy-intensity schistosome infections. Prevalence of STH infection did not significantly change, with 10.8% (95% CI: 9.36-12.5%) of children positive in 2013 and 9.4% (95% CI: 8.0-10.9%) in 2018 (P = 0.182). Heavy-intensity STH infections were found in < 1% of children with hookworm, and none in children with A. lumbricoides or T. trichiura in either study. The WASH data were collected in 2018, indicating 43.6% of schools had a latrine and 14.4% had handwashing facilities. Although progress is evident, SCH remains a public health problem in Nasarawa and Plateau states.

Sensitivity Analysis of a Transmission Interruption Model for the Soil-Transmitted Helminth Infections in Kenya

As the world rallies toward the endgame of soil-transmitted helminths (STH) elimination by the year 2030, there is a need for efficient and robust mathematical models that would enable STH programme managers to target the scarce resources and interventions, increase treatment coverage among specific sub-groups of the population, and develop reliable surveillance systems that meet sensitivity and specificity requirements for the endgame of STH elimination. However, the considerable complexities often associated with STH-transmission models underpin the need for specifying a large number of parameters and inputs, which are often available with considerable degree of uncertainty. Additionally, the model may behave counter-intuitive especially when there are non-linearities in multiple input-output relationships. In this study, we performed a global sensitivity analysis (GSA), based on a variance decomposition method: extended Fourier Amplitude Sensitivity Test (eFAST), to a recently developed STH-transmission model in Kenya (an STH endemic country) to; (1) robustly compute sensitivity index (SI) for each parameter, (2) rank the parameters in order of their importance (from most to least influential), and (3) quantify the influence of each parameter, singly and cumulatively, on the model output. The sensitivity analysis (SA) results demonstrated that the model outcome (STH worm burden elimination in the human host) was significantly sensitive to some key parameter groupings: combined effect of improved water source and sanitation (ϕ), rounds of treatment offered (τ), efficacy of the drug used during treatment (h), proportion of the adult population treated (g_a: akin to community-wide treatment), mortality rate of the mature worms in the human host (μ), and the strength of the -dependence of worm egg production (γ). For STH control programmes to effectively reach the endgame (STH elimination in the entire community), these key parameter groupings need to be targeted since together they contribute to a strategic public health intervention.

Schistosomiasis, soil transmitted helminthiasis, and malaria co-infections among women of reproductive age in rural communities of Kwale County, coastal Kenya

Background

Schistosoma haematobium, soil transmitted helminthes (STH), and malaria lead to a double burden in pregnancy that eventually leads to poor immunity, increased susceptibility to other infections, and poor pregnancy outcomes. Many studies have been carried out on pre-school and school aged children but very little has been done among the at risk adult population including women of reproductive age (WRA). Our current study sought to establish the risk factors and burden of co-infection with S. haematobium, STH, and Plasmodium sp. among WRA in Kwale County, Coastal Kenya.

Methods

A total of 534 WRA between the ages of 15–50 were enrolled in this cross-sectional study from four villages; Bilashaka and Mwaluphamba in Matuga sub-County, and Mwachinga and Dumbule in Kinango sub-County. Socio-demographic information was collected using a pre-tested standardized questionnaire. Parasitological examination was done using urine filtration method for Schistosoma haematobium, Kato Katz for STH (Ascaris lumbricoides, Hookworm, Trichuris trichiura), and standard slide microscopy for Plasmodium sp. Statistical analyses were carried out using STATA version 15.1.

Results

The overall prevalence of S. haematobium was 3.8% (95% CI: 2.6–5.4) while that for malaria was 4.9% (95% CI: 2.0–11.7). The prevalence of STH was 5.6% (95% CI: 2.8–11.3) with overall prevalence of 5.3% (95% CI: 2.5–10.9) for hookworm and 0.6% (95% CI: 0.2–1.9) for T. trichiura. The occurrence of co-infection was low and was recorded between S. haematobium and P. falciparum (0.6%), followed by S. haematobium and STH (0.4%).

Among pregnant women, 2.6% had co-infection with S. haematobium and P. falciparum. Only 1.3% had co-infection with S. haematobium and hookworm or T. trichiura. Among non-pregnant women, co-infection with S. haematobium and P. falciparum was 0.2%. Similarly, co-infection with S. haematobium and hookworm or T. trichiura was 0.2%.

Bed net ownership and usage among pregnant women was 87.8 and 96.6%, respectively. 66.3% of the women reported using improved water sources for drinking while 78.1% reported using improved sanitation facilities.

Conclusion

The use of improved WASH activities might have contributed to the low prevalence of STHs and S. haematobium infections. Further, bed net ownership and usage might have resulted in the low prevalence of Plasmodium sp. infections observed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12526-0.

Prevalence and Correlation Analysis of Soil-Transmitted Helminths Infections and Treatment Coverage for Preschool and School Aged Children in Kenya: Secondary Analysis of the National School Based Deworming Program Data

Background: Soil-transmitted helminths (STH) are among the most common parasitic infections globally, disproportionately affecting children. Treatment of STH in Kenya is often targeted at preschool (PSAC) and school aged (SAC) children delivered through annual mass drug administration (MDA) in primary schools. Understanding group-specific prevalence and dynamics between treatment and coverage is critical for continued treatment success. This study aims to provide detailed information on group-specific infection prevalence and relative reductions (RR), and their relationships with treatment coverage over time. Additionally, it aims to quantify the correlation between the observed school level infection prevalence and treatment coverage. Methods: Secondary analysis of existing data collected between 2012 and 2018 by the monitoring and evaluation (M&E) program of the National School-Based Deworming (NSBD) program was used. The M&E program conducted surveys utilizing cross-sectional study design, at four survey time points, in a nationally-representative sample of schoolchildren across counties in Kenya. In each participating school, the program randomly sampled 108 children per school, of both groups. Infection prevalence was estimated using binomial regression, RR in prevalence using multivariable mixed effects model, statistical correlations using structural equation modeling, and change-point-analysis using the binary segmentation algorithm. Results: Overall, STH prevalence for PSAC was 33.7, 20.2, 19.0, and 17.9% during Year 1 (Y1), Year 3 (Y3), Year 5 (Y5), and Year 6 (Y6) surveys, respectively with an overall RR of 46.9% (p = 0.001) from Y1 to Y6. Similarly, overall STH prevalence for SAC was 33.6, 18.4, 14.7, and 12.5% during Y1, Y3, Y5, and Y6 surveys, respectively with an overall RR of 62.6% (p < 0.001). An overall (all time points) significant but very weak negative correlation was found between treatment coverage and undifferentiated STH prevalence (r = -0.144, p = 0.002) among PSAC but not in SAC. Further, we observed inter-county heterogeneity variation in infection prevalence, RR, as well as correlations. Conclusion: The analysis showed that after six rounds of MDA, prevalence of STH has significantly declined among both groups of children, however not to a point where it is not a public health problem (below 1%). The analysis, additionally established an overall significant but weak negative correlation between treatment coverage and prevalence, indicating that the current treatment coverage might not be sufficient to drive the overall STH prevalence to below 1%. These findings will allow STH control programs in Kenya to make decisions that will accelerate the attainment of STH elimination as a public health problem.

DNA damage repair: historical perspectives, mechanistic pathways and clinical translation for targeted cancer therapy

Genomic instability is the hallmark of various cancers with the increasing accumulation of DNA damage. The application of radiotherapy and chemotherapy in cancer treatment is typically based on this property of cancers. However, the adverse effects including normal tissues injury are also accompanied by the radiotherapy and chemotherapy. Targeted cancer therapy has the potential to suppress cancer cells' DNA damage response through tailoring therapy to cancer patients lacking specific DNA damage response functions. Obviously, understanding the broader role of DNA damage repair in cancers has became a basic and attractive strategy for targeted cancer therapy, in particular, raising novel hypothesis or theory in this field on the basis of previous scientists' findings would be important for future promising druggable emerging targets. In this review, we first illustrate the timeline steps for the understanding the roles of DNA damage repair in the promotion of cancer and cancer therapy developed, then we summarize the mechanisms regarding DNA damage repair associated with targeted cancer therapy, highlighting the specific proteins behind targeting DNA damage repair that initiate functioning abnormally duo to extrinsic harm by environmental DNA damage factors, also, the DNA damage baseline drift leads to the harmful intrinsic targeted cancer therapy. In addition, clinical therapeutic drugs for DNA damage and repair including therapeutic effects, as well as the strategy and scheme of relative clinical trials were intensive discussed. Based on this background, we suggest two hypotheses, namely "environmental gear selection" to describe DNA damage repair pathway evolution, and "DNA damage baseline drift", which may play a magnified role in mediating repair during cancer treatment. This two new hypothesis would shed new light on targeted cancer therapy, provide a much better or more comprehensive holistic view and also promote the development of new research direction and new overcoming strategies for patients.

Environmental factors influencing Prevention and Control of Schistosomiasis Infection in Mwea, Kirinyaga County Kenya: A cross sectional study

Background

Schistosomiasis remains a major public health problem in Kenya. Environmental factors are critical in creating a medium for growth and spread of schistosomiasis vectors. The study investigated the environmental factors influencing prevention and control of schistosomiasis infection in Mwea West Sub County, Kirinyaga County-Kenya.

Methods

A multi stage sampling was used to identify four hundred and sixty-five (465) household. Analytical descriptive cross-sectional design that utilised quantitative data collection method was used. Data was collected using a pretested structured questionnaire and analysed using Chi square tests or Fisher's exact tests where applicable.

Results

Study results indicated a significant association p<.001 between household level of education, members being affected by floods during the rainy season and schistosomiasis infection. The result further indicates level of significance (p<0.047) in the association between sources of water in a household and schistosomiasis infection. No level of significance was posted between having a temporary water body in the area p (=.072) and schistosomiasis infection. In addition, there was no significant association between proximity to the nearest water source, p=.074 and proximity to the nearest health facility p=0.356 with schistosomiasis infection.

Conclusions

The study recommends carefully designing safe water sources in order to match the goal of effectively controlling and reversing the trends of schistosomiasis infections. The community should be made aware of the risk factors of schistosomiasis including water utilised in the household's alongside raising health seeking behaviours for diagnosis and treatment of schistosomiasis as a way of reducing the spread of infection.

Statistical Regression Model of Water, Sanitation, and Hygiene; Treatment Coverage; and Environmental Influences on School-Level Soil-Transmitted Helminths and Schistosome Prevalence in Kenya: Secondary Analysis of the National Deworming Program Data

According to the Kenya National School-Based Deworming program launched in 2012 and implemented for the first 5 years (2012-2017), the prevalence of soil-transmitted helminths (STH) and schistosomiasis substantially reduced over the mentioned period among the surveyed schools. However, this reduction is heterogeneous. In this study, we aimed to determine the factors associated with the 5-year school-level infection prevalence and relative reduction (RR) in prevalence in Kenya following the implementation of the program. Multiple variables related to treatment, water, sanitation, and hygiene (WASH) and environmental factors were assembled and included in mixed-effects linear regression models to identify key determinants of the school location STH and schistosomiasis prevalence and RR. Reduced prevalence of Ascaris lumbricoides was associated with low (< 1%) baseline prevalence, seven rounds of treatment, high (50-75%) self-reported coverage of household handwashing facility equipped with water and soap, high (20-25°C) land surface temperature, and community population density of 5-10 people per 100 m2. Reduced hookworm prevalence was associated with low (< 1%) baseline prevalence and the presence of a school feeding program. Reduced Trichuris trichiura prevalence was associated with low (< 1%) baseline prevalence. Reduced Schistosoma mansoni prevalence was associated with low (< 1%) baseline prevalence, three treatment rounds, and high (> 75%) reported coverage of a household improved water source. Reduced Schistosoma haematobium was associated with high aridity index. Analysis indicated that a combination of factors, including the number of treatment rounds, multiple related program interventions, community- and school-level WASH, and several environmental factors had a major influence on the school-level infection transmission and reduction.

Modeling the Interruption of the Transmission of Soil-Transmitted Helminths Infections in Kenya: Modeling Deworming, Water, and Sanitation Impacts

Kenya, just like other countries with endemic soil-transmitted helminths (STH), has conducted regular mass drug administration (MDA) program for the last 5 years among school aged children as a way to reduce STH infections burden in the country. However, the point of interruption of transmission of these infections still remains unclear. In this study, we developed and analyzed an age structured mathematical model to predict the elimination period (i.e., time taken to interrupt STH transmission) of these infections in Kenya. The study utilized a deterministic age structured model of the STH population dynamics under a regular treatment program. The model was applied to three main age groups: pre-school age children (2-4 years), school age children (5-14 years), and adult populations (≥15 years) and compared the impact of two interventions on worm burden and elimination period. The model-simulated results were compared with the 5 year field data from the Kenyan deworming program for all the three types of STH (Ascaris lumbricoides, Trichuris trichiura, and hookworm). The model demonstrated that the reduction of worm burden and elimination period depended heavily on four parameter groups; drug efficacy, number of treatment rounds, MDA and water, sanitation and hygiene (WASH) coverage. The analysis showed that for STH infections to be eliminated using MDA alone in a short time period, 3-monthly MDA plan is desired. However, complementation of MDA with WASH at an optimal (95%) coverage level was most effective. These results are important to the Kenyan STH control program as it will guide the recently launched Breaking Transmission Strategy.

Prevalence, Intensity, and Correlates of Soil-Transmitted Helminth Infections among School Children after a Decade of Preventive Chemotherapy in Western Rwanda

Preventive chemotherapy (PC) is a WHO-recommended core intervention measures to eliminate Soil-Transmitted Helminths (STH) as a public health problem by 2020, defined as a reduction in prevalence to <1% of moderate or high-intensity infection. We conducted a cross-sectional study to investigate the prevalence, intensity, and correlates of STH after a decade of PC in Rwanda. A total of 4998 school children (5–15 years old) from four districts along Lake Kivu in the western province were screened for STH using Kato-Katz. The overall prevalence of Soil-transmitted helminths among school children was 77.7% (range between districts = 54% to 92%). Trichirus trichiura was the most common STH (66.8%, range between districts = 23% to 88.2%), followed by Ascaris lumbricoides (49.9%, range between district = 28.5% to 63.3%) and hookworms (1.9%, range between districts = 0.6% to 2.9%). The prevalence of single, double and of triple parasite coinfection were 48.6%, 50.3%, and 1.1%, respectively. The overall prevalence of moderate or high-intensity infection for Trichirus trichiura and Ascaris lumbricoides was 7.1% and 13.9, respectively. Multivariate logistic regression model revealed that male sex, district, stunting, and schistosomiasis coinfection as significant predictors of STH infection. Despite a decade of PC implementation, STH remain a significant public health problem in Rwanda.