<i>Biomphalaria pfeifferi</i>Snails and Intestinal Schistosomiasis, Lake Malawi, Africa, 2017–2018

Alharbi, Mohammad; Condemine, Charlotte; Christiansen, Rosie; LaCourse, E. James; Makaula, Peter; Stanton, Michelle C.; Juziwelo, Lazarus; Kayuni, Seke; Stothard, J. Russell

doi:10.3201/eid2503.181601

“…A cross-sectional study design was used to achieve the three study objectives, see STROBE checklist within supplemental materials. Based on previous epidemiological information [6], a sample size calculation with single population proportion formula (http://www.raosoft.com/ samplesize.html) showed that a total sample size of 520 was sufficient to estimate overall prevalence of intestinal and urogenital schistosomiasis with < ± 5% precision and 95% confidence.…”

Section: Study Design and Sample Size Determination For Each Objectivementioning

confidence: 99%

“…This appraisal was revised in May 2018 as, since November 2017 B. pfeifferi has been repeatedly encountered in the lake, alongside emergence of intestinal schistosomiasis documented in three local primary schools [6]. Prevalence of infection by 'trace/positive' urine circulating cathodic antigen (CCA)-dipsticks was 34.3% (95% CI: 27.9-41.3), with ova-patent S. mansoni in stool noted at Samama and Mchoka schools [6]. Even with ongoing annual MDA for urogenital schistosomiasis control, the dynamics of intestinal schistosomiasis need further scrutiny here, for this disease could transition from emergence to outbreak.…”

Section: Introductionmentioning

confidence: 99%

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

Kayuni

¹

,

O’Ferrall

²

,

Baxter

³

et al. 2020

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Background: Intestinal schistosomiasis was not considered endemic in Lake Malawi until November 2017 when populations of Biomphalaria pfeifferi were first reported; in May 2018, emergence of intestinal schistosomiasis was confirmed. This emergence was in spite of ongoing control of urogenital schistosomiasis by preventive chemotherapy. Our current study sought to ascertain whether intestinal schistosomiasis is transitioning from emergence to outbreak, to judge if stepped-up control interventions are needed. Methods: During late-May 2019, three cross-sectional surveys of primary school children for schistosomiasis were conducted using a combination of rapid diagnostic tests, parasitological examinations and applied morbiditymarkers; 1) schistosomiasis dynamics were assessed at Samama (n = 80) and Mchoka (n = 80) schools, where Schistosoma mansoni was first reported, 2) occurrence of S. mansoni was investigated at two non-sampled schools, Mangochi Orphan Education and Training (MOET) (n = 60) and Koche (n = 60) schools, where B. pfeifferi was nearby, and 3) rapid mapping of schistosomiasis, and B. pfeifferi, conducted across a further 8 shoreline schools (n = 240). After data collection, univariate analyses and Chi-square testing were performed, followed by binary logistic regression using generalized linear models, to investigate epidemiological associations.

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“…A cross-sectional study design was used to achieve the three study objectives, see STROBE checklist within supplemental materials. Based on previous epidemiological information [6], a sample size calculation with single population proportion formula (http://www.raosoft.com/samplesize.html) showed that a total sample size of 520 was su cient to estimate overall prevalence of intestinal and urogenital schistosomiasis with < ± 5% precision and 95% con dence.…”

Section: Study Design and Sample Size Determination For Each Objectivementioning

confidence: 99%

“…Based on prevalence data provided by the authors of the May 2018 study [6] [11]. Random sampling was used at each school following strati cation by age and gender.…”

Section: Study Design and Sample Size Determination For Each Objectivementioning

confidence: 99%

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

Kayuni

¹

,

O’Ferrall

²

,

Baxter

³

et al. 2020

Preprint

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1

2

0

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Background: Intestinal schistosomiasis was not considered endemic in Lake Malawi until November 2017 when populations of Biomphalaria pfeifferi were first reported; in May 2018, emergence of intestinal schistosomiasis was confirmed. This emergence was in spite of ongoing control of urogenital schistosomiasis by preventive chemotherapy. Our current study sought to ascertain whether intestinal schistosomiasis is transitioning from emergence to outbreak, to judge if stepped-up control interventions are needed.Methods: During late-May 2019, three cross-sectional surveys of primary school children for schistosomiasis were conducted using a combination of rapid diagnostic tests, parasitological examinations and applied morbidity-markers; 1) schistosomiasis dynamics were assessed at Samama (n = 80) and Mchoka (n = 80) schools, where Schistosoma mansoni was first reported, 2) occurrence of S. mansoni was investigated at two non-sampled schools, Mangochi Orphan Education and Training (MOET) (n = 60) and Koche (n = 60) schools, where B. pfeifferi was nearby, and 3) rapid mapping of schistosomiasis, and B. pfeifferi, conducted across a further 8 shoreline schools (n = 240). After data collection, univariate analyses and Chi-square testing were performed, followed by binary logistic regression using generalized linear models, to investigate epidemiological associations.Results: In total, 520 children from 12 lakeshore primary schools were examined, mean prevalence of S. mansoni by ‘positive’ urine circulating cathodic antigen (CCA)-dipsticks was 31.5% (95% Confidence Interval (CI): 27.5–35.5). Upon comparisons of infection prevalence in May 2018, significant increases at Samama (Relative Risk (RR) = 1.7, 95% CI: 1.4–2.2) and Mchoka (RR = 2.7, 95% CI: 1.7–4.3) schools were observed. Intestinal schistosomiasis was confirmed at MOET (18.3%) and Koche (35.0%) schools, and in all rapid mapping schools, ranging from 10.0% to 56.7%. Several populations of B. pfeifferi were confirmed, with two new eastern shoreline locations noted. Mean prevalence of urogenital schistosomiasis was 24.0% (95% CI: 20.3–27.7). Conclusions: We notify that intestinal schistosomiasis, once considered non-endemic in Lake Malawi, is now transitioning from emergence to outbreak. Once control interventions can resume after coronavirus disease 2019 (COVID-19) suspensions, we recommend stepped-up preventive chemotherapy, with increased community-access to treatments, alongside renewed efforts in appropriate environmental control.

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“…The present case is the 15th cases reported in the literature so far and it is suspected that the patient was exposed to water infested with schistosome cercariae during her residence in Kenya and Malawi, where 2 major forms of schistosomiasis are prevalent. Both urogenital and intestinal schistosomiasis are prevalent in Lake Malawi, one of the largest lakes in Central Africa, where co-infection occurs in infected schoolchildren [8]. In Scotland, the majority of new cases of schistosomiasis between 2005 and 2009 were identified from travelers returning from Malawi [9].…”

Section: Discussionmentioning

confidence: 99%

Case Report of Urinary Schistosomiasis in a Returned Traveler in Korea

Lee

¹

,

Song

²

,

Jung

³

et al. 2020

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A 23-year-old Korean woman with a residence history in Kenya and Malawi for about 2 years presented with gross hematuria for 1 month. Blood tests were within normal range except eosinophilia. Asymmetrically diffuse wall thickening and calcification were observed at the urinary bladder on CT. Multiple erythematous nodular lesions were observed in the cystoscopy and transurethral resection was done. Numerous eggs of Schistosoma haematobium with granulomatous inflammation were observed in the submucosal layer of the bladder. The patient was diagnosed with schistosomiasis-related cystitis and treated with praziquantel (40 mg/kg/day) twice before and after transurethral resection. This case suggests that S. haematobium infection should be considered as a cause of hematuria in Korea when the patient had a history of traveling endemic areas of schistosomiasis.

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Biomphalaria pfeifferiSnails and Intestinal Schistosomiasis, Lake Malawi, Africa, 2017–2018

Cited by 26 publications

References 9 publications

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

Case Report of Urinary Schistosomiasis in a Returned Traveler in Korea

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