Prevalence of Schistosoma mansoni and Associated Risk Factors in Human and Biomphalaria Snails in Ethiopia: A Systematic Review and Meta-analysis

Knowledge, attitude and practice towards intestinal schistosomiasis among school-aged children and adults in Amhara Regional State, northwest Ethiopia. A cross-sectional study

BACKGROUND

Schistosoma mansoni causes intestinal schistosomiasis (SCH) in all regions of Ethiopia. Despite many years of mass treatment, the prevalence has not dropped significantly. The reduction of SCH transmission demands the integration of deworming with safe water, sanitation, and hygiene (WASH) activities. Adequate knowledge and a positive attitude towards SCH are critical to practicing those interventions. However, data on the knowledge, attitude, and practice (KAP) level in school and community settings is limited in Ethiopia.

METHODS

School and community-based cross-sectional studies were conducted from February to June 2023 among 634 school-aged children (SAC) and 558 adults. A pre-tested questionnaire was used to collect socio-demographic and KAP data. Records were entered and analyzed using SPSS software version 21. Correct responses for each of the KAP questions were scored as one, while incorrect or 'I don't know' responses were scored as zero. Good knowledge, a positive attitude and good practice were declared if percentage scores were ≥ 80%, ≥ 90% and ≥ 75%, respectively.

RESULTS

Only 229 (19.2%) respondents, comprising 91 (14.4%) SAC and 138 (24.7%) adults, had ever heard of SCH. Adults, males, and urban residents had higher awareness level compared to their respective counterparts (p < 0.05). Only 28.4% of aware respondents knew that swimming or bathing in freshwater is a risk factor for schistosoma infection; 10.9% knew the etiologic agent; and 14.4% mentioned at least one sign and symptom associated with SCH. The majority (97.8%) of the respondents were willing to take therapeutic drugs, but only 37.6% believed that SCH is a serious disease. Regarding risky practices, 89.5% practiced swimming or bathing in freshwater, and 25.3% had no access to piped water. Among the aware respondents, only 18 (7.9%) had good knowledge, while 30 (13.1%) had a positive attitude towards SCH. Ninety-nine (43.2%) respondents had good Schistosoma infection prevention practices.

CONCLUSIONS

The knowledge, attitude, and preventive practice level towards schistosomiasis are low in the study area. Therefore, strengthening school and community-based health education, along with mass drug administration (MDA), WASH, and a vector control program, is recommended for preventing SCH.

Efficacy and safety of prazequantel for the treatment of Schistosoma mansoni infection across different transmission settings in Amhara Regional State, northwest Ethiopia

BACKGROUND

Schistosoma mansoni and S. haematobium infections have been public health problems in Ethiopia, S. mansoni being more prevalent. To reduce the burden of schistosomiasis, a national school-based prazequantel (PZQ) mass drug administration (MDA) program has been implemented since November 2015. Nevertheless, S. mansoni infection is still a major public health problem throughout the country. Reduced efficacy of PZQ is reported by a few studies in Ethiopia, but adequate data in different geographical settings is lacking. Hence, this study aimed to assess the efficacy and safety of PZQ for the treatment of S. mansoni infection across different transmission settings in Amhara Regional State, northwest Ethiopia.

METHODS

A school-based single-arm prospective cohort study was conducted from February to June, 2023 among 130 S. mansoni-infected school-aged children (SAC). Forty-two, 37, and 51 S. mansoni-infected SAC were recruited from purposely selected schools located in low, moderate, and high transmission districts, respectively. School-aged children who were tested positive both by Kato Katz (KK) using stool samples and by the point of care circulating cathodic antigen (POC-CCA) test using urine samples at baseline were treated with a standard dose of PZQ and followed for 21 days for the occurrence of adverse events. After three weeks post-treatment, stool and urine samples were re-tested using KK and POC-CCA. Then the cure rate (CR), egg reduction rate (ERR), and treatment-associated adverse events were determined. The data were analyzed using SPSS version 21.

RESULTS

Out of the total 130 study participants, 110 completed the follow-up. The CR and ERR of PZQ treatment were 88.2% (95%CI: 82.7-93.6) and 93.5% (95%CI: 85.4-98.5), respectively, by KK. The CR of PZQ based on the POC-CCA test was 70.9% (95%CI: 62.7-79.1) and 75.5% (95%CI: 67.3-83.6) depending on whether the interpretation of 'trace' results was made as positive or negative, respectively. After treatment on the 21st day, 78 and 83 participants tested negative both by KK and POC-CCA, with respective interpretations of 'trace' POC-CCA test results as positive or negative. The CR in low, moderate and high transmission settings was 91.7%, 91.2% and 82.5%, respectively (p = 0.377) when evaluated by KK. The CR among SAC with a light infection at baseline (95.7%) by KK was higher than that of moderate (81.5%) and heavy (64.3%) infections (χ2 = 12.53, p = 0.002). Twenty-six (23.6%) participants manifested at least one adverse event. Eleven (10.0%), eight (7.3%), six (5.5%), and three (2.7%) participants complained about abdominal pain, nausea, headache, and anorexia, respectively. All adverse events were mild, needing no intervention. Occurrence of adverse events was slightly higher in high endemic areas (32.5%) than moderate (23.5%) and low endemic areas (p = 0.279).

CONCLUSIONS

A single dose of 40 mg/kg PZQ was efficacious and safe for the treatment of S. mansoni infection when it was evaluated by the KK test, but a lower efficacy was recorded when it was evaluated by the POC-CCA test. However, the POC-CCA test's specificity, clearance time of CCA from urine after treatment, and interpretation of weakly reactive (trace) test results need further research.

Burden and risk factors for Schistosoma mansoni infection among primary school children: A quantitative school-based cross-sectional survey in Busega district, Northern Tanzania

BACKGROUND

Intestinal schistosomiasis is one of the most common neglected tropical diseases in Tanzania. Despite massive praziquantel administration, data from Northern Tanzania have reported a prevalence of up to 93.2%. Because the disease is focal, depending on host, environmental and intermediate host factors, there is a need to acquire data in specific settings to better tailor interventions. Therefore, the study assessed the prevalence and factors associated with persistent transmission of intestinal schistosomiasis among school-age children in Busega district, Northern Tanzania.

METHODS

A school-based cross-sectional study was conducted among 363 primary school children, randomly selected from school clusters in the Busega district. A single stool sample was collected from each child for S. mansoni ova and infection intensity examination using Kato-Katz. Factors related to intestinal schistosomiasis transmission were acquired through a questionnaire. A malacological survey was carried out to determine the Biomphalaria infectivity rate. Descriptive statistics and logistic regression analysis were conducted to analyse the association between schistosoma infection and factors related to transmission in this setting.

RESULTS

The prevalence of S. mansoni infection was 41.3% (95% CI: 36.3-46.5), statistically significantly higher among the younger group aged less than 11 years (46.4% vs 35.3%, p = 0.032). The intensity of infection was heavy in 1.6% of participants, moderate in 9.6%, and light in 30.9%. Studying at Mwamayombo Primary School (AOR = 2.50, 95% CI: 1.12-5.60) was the only factor significantly associated with S. mansoni infestations. The snail intermediate host belonged to Biomphalaria sudanica species, whose infectivity rate was quantified as 0.97%, thus confirming ongoing transmission in the area.

CONCLUSIONS

There was a high prevalence of S. mansoni infection among school-age children in the Busega district. The presence of the infected Biomphalaria sudanica in the area documents the persistent transmission of the disease, favored by low knowledge and negative attitudes among school-aged children. Hence, the need for multi-approach intervention for schistosomiasis prevention and elimination.

Parasitological and malacological surveys to identify transmission sites for Schistosoma mansoni in Gomma District, south-western Ethiopia

Schistosomiasis is a neglected tropical disease that disproportionately affects the poorest people in tropical and subtropical countries. It is a major parasitic disease causing considerable morbidity in Ethiopia. Despite significant control efforts, schistosomiasis transmission is still widespread in many rural areas of the country. The aim of this study was to determine the prevalence and intensity of intestinal schistosomiasis among schoolchildren, as well as to identify schistosomiasis transmission sites in Gomma District, southwestern Ethiopia. Between October 2018 and September 2019, cross-sectional parasitological and malacological surveys were conducted in the study area. The study comprised 492 school-children aged 6 to 15 years old from four primary schools in Gomma District. To identify and quantify eggs of Schistosoma mansoni from the children, stool specimens were collected and processed using double Kato-Katz thick smears. Water bodies adjacent to human settlements in the study area were surveyed for snail intermediate hosts of S. mansoni. Morphological identification of collected snails was conducted, followed by examining their infection status using a dissecting microscope. The overall prevalence of S. mansoni infection was 73.8% (95%CI: 69.9-77.7%) and 41.6% of them had moderate-to-heavy infections. The prevalence of S. mansoni infection differed considerably by age group, with the older age groups (12-15) having a higher prevalence than the younger age groups (6-11) (p < 0.001). The prevalence of infection also varied significantly among schools; Dedo Ureche had the highest prevalence (86.9%) (p = 0.034), while Goga Kilole had relatively the lowest prevalence of S. mansoni infection (59.6%) (p = 0.003). A total of 1463 Biomphalaria pfeifferi snails were collected from 11 survey sites throughout the study area, with 357 (24.4%) of the snails shedding schistosomes cercariae. Despite intensified efforts to scale up mass drug administration in Ethiopia, this study reported high levels of S. mansoni infection among schoolchildren and snail intermediate hosts in rural communities in Gomma. Such a high infection rate warrants pressing needs for targeted and integrated interventions to control the disease in the area.

Distribution and seasonal abundance of Biomphalaria snails and their infection status with Schistosoma mansoni in and around Lake Tana, northwest Ethiopia

Biomphalaria snails, namely B. pfeifferi and B. sudanica, are the principal intermediate hosts for Schistosoma mansoni infection in Ethiopia. Epidemiological studies of Biomphalaria snails and their infection status with S. mansoni is vital for public health planning. This study aimed to assess the spatial and seasonal abundance of Biomphalaria snails as well as their infection status with S. mansoni around Lake Tana, northwest Ethiopia. Malacological survey was conducted from January 2021 to December 2021 in ten different collection sites in and around Lake Tana. Snail collection was performed for 20 min from each collection site seasonally (four times in a year) using a standard scoop and handpicking from aquatic vegetation. All collected snails were carefully examined based on their morphological features and all live Biomphalaria snails were subjected to cercariae shedding experiment. Descriptive statistics were used to determine the prevalence of S. mansoni infection and its relationship with snail collection sites and seasons. A total of 3886 freshwater snails were collected from ten collection sites around Lake Tana. Out of the total snails collected, 1606 (41.3%; 95% CI 39.77-42.89%) were Biomphalaria spp. The highest (374) and the lowest numbers (98) of Biomphalaria snails were collected from Shinne River and Qunzela Lakeshore, respectively. Out of the 1375 live Biomphalaria snails, 14.4% (95% CI 12.59-16.37%) snails shed cercariae, but only 4.87% (95% CI 3.79-6.15%) were cercariae of S. mansoni. The infection prevalence of S. mansoni ranged from 10.59% at the Cherechera site to 1.49% at Gumara River. Biomphalaria snail infections with S. mansoni cercariae were observed throughout the season, the highest and the lowest infection rates being in the spring and summer seasons. Significant differences in the prevalence of S. mansoni infection in Biomphalaria snails were observed across study sites and seasons (p < 0.05). Biomphalaria snails were the most abundant freshwater snails found in nearly all of snail collection sites throughout the year. It was revealed that nearly five percent of Biomphalaria snails were infected with S. mansoni cercariae. This study highlights the importance of appropriate snail control strategies to support the ongoing prevention and control of schistosomiasis around Lake Tana.

Schistosoma mansoni Epidemiology Among Snails, Rodents and Children: A One Health Approach

Background

Schistosoma is one of the prevalent parasitic infection in humans and animals. Schistosomiasis in children is particularly serious and results in liver and spleen enlargement, anemia, stunting, reduced ability to learn and death. The aim of this study was to measure the prevalence and distribution of schistosomiasis in children, rodents and snail populations in Aleffa and Takusa districts, north-west Ethiopia.

Methods

Disease status and exposure were simultaneously measured from December 2020 to December 2021. School children's stool specimens were collected for schistosomiasis examination by Kato Katz and formal-ether techniques. Live rodents and snails were trapped and collected in search of adult schistosoma, eggs, and cercariae, respectively. Multiple logistic regression analytic technique by using SPSS version 20 was conducted.

Results

Of 460 stool specimens examined, 116 (25.22) were found positive for S. mansoni infection. In the present finding, the possible determinants for the occurrence of intestinal schistosomiasis in school children were female sex (AOR = 1.09, 95% CI: 1.37–2.96); working with bare foot (AOR = 1.21, 95% CI: 1.08–1.52); skin cut/abrasion history (AOR = 3.6, 95% CI: 1.08–7.43) and swimming habit (AOR = 1.58, 95% CI: 1.33–1.99). The overall (n = 108) rodent prevalence of S. mansoniwas 23 (21.3%). Only 6 snails were shedding the infective stage of schistosoma cercariae.

Conclusion

The study revealed that there is a moderate prevalence of schistosomiasis in different hosts. Thus, multi-host intervention is crucial to achieving the goal of interrupting transmission of schistosomiasis in the study area. Further research to better understand and exploit the broader environmental, ecological context and encompassing dynamic interactions between all hosts over time will be crucial for building predictive models beyond the known fact of having or not having reservoirs/hybridization of schistosoma in our study area.

Prevalence, intensity and associated risk factors of Schistosoma mansoni infections among schoolchildren around Lake Tana, northwestern Ethiopia

BACKGROUND

Schistosomiasis is one of the widely distributed neglected tropical diseases. It is a serious public health problem in sub-Saharan Africa. The disease is highly prevalent and widely distributed in Ethiopia due to suitable environmental factors and human activities. The prevalence and infection intensity varied from locality to locality in the country. This study aimed to assess the prevalence and intensity of S. mansoni infection and associated risk factors among schoolchildren around Lake Tana.

METHODS

A school-based cross-sectional study was conducted among 710 schoolchildren from February to April 2021 in eight selected primary schools around Lake Tana. A questionnaire was used to collect data on socio-demographic information and potential risk factors of S. mansoni infection. After collecting socio-demographic information, students were requested to bring about 2grams of stool specimens for parasitological examination. The collected stool samples were processed using a single Kato-Katz and Ritchie's concentration techniques. The data were analyzed using SPSS software version 23 and factors with a p-value < 0.05 were considered as statistically significant.

RESULTS

The overall prevalence of S. mansoni was 34.9% (95% CI: 31.4-38.7) among schoolchildren in the study area. The eggs per gram (EPG) of stool ranged from 24 to 1659 with arithmetic and geometric mean values of 138.1 EPG and 85.1 EPG, respectively. The majority of S. mansoni infections (61.4%) were classified as low infection intensity. Among the different determinant factors being male (AOR = 1.74; 95%CI = 1.233-2.457; P-value = 0.002), bathing habits (AOR = 1.494; 95%CI = 1.013-2.199; P-value = 0.043) and students attending at Qunzela primary school (AOR = 10.545; 95%CI = 3.264-34.067; P-value = 0.001), Alabo primary school (AOR = 3.386; 95%CI = 1.084-10.572; P-value = 0.036) were significantly associated with S. mansoni infection.

CONCLUSION

This study revealed that more than one-third of schoolchildren were infected by S. mansoni in the study area. The majority of the infections were classified as low infection intensity. Being male, bathing habits and schools in which students attended were independent explanatory factors for S. mansoni infection. Therefore, integrated control strategies are needed to improve the health conditions of schoolchildren in the study area.