Molecular epidemiology of blastocystosis in Malaysia: does seasonal variation play an important role in determining the distribution and risk factors of Blastocystis subtype infections in the\xa0Aboriginal community?

Samseh Abdullah Noradilah,Siti Nor Azreen Abdul Manap,Ii Li Lee,Anisah Nordin,Norhayati Moktar,Fatmah Md Salleh,Wan Omar Abdullah,Noor Shazleen Husnie Mohd Mohtar,Syed Muhamad Azrul,Syamsa Rizal Abdullah,Tengku Shahrul Anuar

doi:10.1186/s13071-017-2294-2

Abstract

BackgroundAlternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics. This cross-sectional study was therefore conducted to provide the prevalence of Blastocystis and to determine the potential risk factors associated with each subtype during the wet and dry seasons in the Aboriginal community, Pahang, Malaysia.MethodsA total of 473 faecal samples were collected: 256 (54.1%) and 217 (45.9%) samples were obtained during the wet (October-November 2014) and the dry season (June 2015), respectively. All fresh faecal samples were subjected to molecular analysis for subtype and allele identification.ResultsOf the 473 samples, 42.6% and 37.8% were positive for Blastocystis ST1, ST2, ST3 and ST4 during wet and dry seasons, respectively. Prevalence of Blastocystis ST1 was significantly higher during the wet season compared to the dry season (Z = 2.146, P < 0.05). Analysis of the association of each Blastocystis subtype with socioeconomic characteristics showed the presence of other family members infected with Blastocystis ST3 and the use of stored river water for domestic activities were the significant risk factors for Blastocystis ST3 infections during both seasons. Untreated water supply and low monthly household income (less or equal to RM 500) were the other significant risk factors for Blastocystis ST3 infections during wet and dry season, respectively. The presence of other family members with Blastocystis ST1 and ST2 was the only significant risk factor associated with ST1 and ST2 infections during both seasons. We hypothesise that transmission of Blastocystis ST1, ST2 and ST3 occurred from person to person during both seasons. The waterborne transmission was also identified as a mode of transmission of Blastocystis ST3.ConclusionThe significant risk factors identified in this study were important in the dynamic transmission of Blastocystis infections during both seasons. Provision of treated water supply and health education are affirmative actions to be taken to control Blastocystis infections in this community.

Highlights

Alternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics
The results show that age of less or equal to 15 years old (OR = 0.431, 95% confidence interval (CI): 0.210–0.887, P = 0.020), presence of other family members infected with ST1 (OR = 5.170, 95% CI: 2.535–10.544, P < 0.001) and occupation as rubber tapper and farmer, (OR = 1.181, 95% CI: 0 .043–0.755, P = 0.009) were significantly associated with Blastocystis ST1 infections
The present study identified use of stored river water for domestic activities as another strong risk factor that was significantly associated with Blastocystis infection during both seasons

Summary

Introduction

Alternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics. This cross-sectional study was conducted to provide the prevalence of Blastocystis and to determine the potential risk factors associated with each subtype during the wet and dry seasons in the Aboriginal community, Pahang, Malaysia. Blastocystis has been included in WHO Guidelines for Drinkingwater Quality [5]. This parasite has been detected in the tap water (12%) of premises of infected patients [6]. A significant association was established between orphans and the infected childcare workers suggesting person-to-person transmission of Blastocystis [13]

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Results

Discussion

Conclusion