Comparing concentration methods: parasitrap® versus Kato-Katz for studying the prevalence of Helminths in Bengo province, Angola

Abstract

Background: Helminth intestinal parasitoses are responsible for high levels of child mortality and morbidity. Hence, the capacity to diagnose these parasitoses and consequently ensure due treatment represents a factor of great importance. Objectives: The main objective of this study involves comparing two methods of concentration, parasitrap and Kato-Katz, for the diagnosis of intestinal parasitoses in faecal samples. Methods: Sample processing made recourse to two different concentration methods: the commercial parasitrap® method and the Kato-Katz method. Results: We correspondingly collected a total of 610 stool samples from pre-school and school age children. The results demonstrate the incidence of helminth parasites in 32.8% or 32.3% of the sample collected depending on whether the concentration method applied was either the parasitrap method or the Kato-Katz method. We detected a relatively high percentage of samples testing positive for two or more species of helminth parasites. We would highlight that in searching for larvae the Kato-Katz method does not prove as appropriate as the parasitrap method. Conclusion: Both techniques prove easily applicable even in field working conditions and returning mutually agreeing results. This study concludes in favour of the need for deworming programs and greater public awareness among the rural populations of Angola.

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

“…The study showed that 8.9% of the schoolchildren had S. stercoralis infection. This value is higher compared to the prevalence of S. stercoralis infection found in other countries such as 2.1% in Madagascar ( Hakami et al, 2019 ), 2.2% in Zanzibar ( Knopp et al, 2008a ), 5.8% in Ethiopia ( Legesse and Erko, 2004 ), 0.2% in Angola ( Mirante et al, 2016 ) and 2.7% in Thailand ( Sedionoto et al, 2019 ). However, our prevalence is comparable to the 9.7% prevalence reported in the Eastern Caribbean Sea ( Kurup and Hunjan, 2010 ) and the 10.8% prevalence in Zanzibar ( Knopp et al, 2008b ).…”

“…On the other hand, Kato-Katz technique was found not suitable for S. stercoralis ( Machicado et al, 2012 ; Hailu et al, 2020 ; WHO, 2020 ); however, during the field estimation, some of S. stercoralis may be recovered by this technique. The prevalence of strongyloidiasis by Kato-Katz method among preschool and schoolchildren was reported at 4% in Ethiopia ( Amare et al, 2021 ), 2.1% in Madagascar ( Hakami et al, 2019 ), 2.2% in Zanzibar ( Knopp et al, 2008a ), 9.7% in the Eastern Caribbean Sea ( Kurup and Hunjan, 2010 ), 5.8% in Ethiopia ( Legesse and Erko, 2004 ), 0.2% in Angola ( Mirante et al, 2016 ) and 2.7% in Thailand ( Sedionoto et al, 2019 ).…”

Formalin-fixed stool improves the performance of the Kato–Katz method

“…Whole stool samples stored at 25°C for 1 day resulted in a 23% (p < 0.0001) and 13% (p < 0.0001) decrease in hookworm FEC, respectively. However, the previous reports have found that both debris particles and egg morphological changes can be misdiagnosed [15,18,19]. Therefore, false-positive Kato-Katz thick smears where several eggs were counted might mistakenly point to another source of error (e.g., writing errors on the entry forms or eggs confused with eggs from different species) [15].…”

Formalin-fixed Stool Improves Performance of the Kato‑Katz method

“…Whole stool samples stored at room temperature for one day resulted in a mean hookworm FEC decrease of 23% (p < 0.0001) versus a 13% reduction (p < 0.0001). However, these previous reports found that both debris particles and egg morphological changes can be misdiagnosed [16,19,20]. Therefore, the false-positive Kato-Katz thick smears where several eggs were counted might mistakenly point to another source of error (e.g.…”