bioRxiv2019
BackgroundIn Malawi, haematobium schistosomiasis is highly endemic. According to previous studies, countermeasures have been conducted mainly in school-aged children. In this study, we focused on the age groups, which are assumed to be major labour force generation. Haematobium schistosomiasis is supposed to be related to occupational activities in schistosome endemic countries. MethodsWe chronologically followed the transition of schistosome egg positive prevalence before and after mass drug administration of praziquantel (MDA) by using a urine filtering examination. We also analyzed the effectiveness of urine reagent strips from the cost perspective. FindingsThe egg positive prevalence was 34.3% (95%CI: 28.5-40.5) just before MDA in June 2010 and the highest prevalence was in the age of twenties. The egg positive prevalence reduced to 12.7% (95%CI: 9.2-17.3, p<0.01) eight weeks after the first MDA and the prevalence reduced to 6.9% (95%CI: 4.6-10.0, p<0.01) after the second MDA in August 2011. The egg positive prevalence after MDA in 2013 was reduced from 3.8% (95%CI: 2.1-6.9) to 0.9% (95%CI: 0.3-3.4) and p value was 0.050. Using urine reagent strips after MDA, the positive predictive value decreased, but the negative predictive value remained high. The cost of one urine reagent strip and one tablet of praziquantel were US$0.06 and US$0.125 in 2013 in Malawi. If the egg positive prevalence is 40%, screening subjects for MDA using urine reagent strips, the cost reduction can be estimated to be about 24% -showing an overall cost reduction. ConclusionThe combination of MDA and urine reagent strips could be both a practical and cost-effective countermeasure for haematobium schistosomiasis. It is key to recognize that haematobium schistosomiasis could be considered a disease that is assumed to have some concern with occupational risk in tropical agricultural countries such as Malawi. From this point of view, it is very important to protect the health of workers; the sound labour force generation is vital for economic growth and development in these countries. Author summarySchistosomiasis is widely endemic in the tropical and subtropical countries including Malawi, and it is related that more than 300 million people suffer from associated severe morbidity. The pathway of transmission is mainly contacting infested fresh water and it is inevitable to contact fresh water through their daily activities in Malawi. Then, they are routinely exposed to the risk of schistosome infection. Previously the main targets of schistosome control were school-aged children, but our research showed main population of schistosome infection was twenties that was presumed to be major labour force. Agriculture is the dominant industry in Malawi and it can be related to be at risk of schistosome infection during agricultural work. Schistosomiasis is presumed to have occupation-related risks, we consider that schistosome control will be a valuable step-up to economic development and make a social contribution in Malawi and many low-income tropical countries. FundingThe Ministry of Education, Culture, Sports, Science and Technology of Japans scientific research grant (JSPS KAKENHI Grant Number JP23406025). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.