2. A single-cell protozoa in human and animal intestine Widely distribute worldwide Highly suspicious as pathogen Many recent study show zoonotic potential of this organisms 2

3. Blastocystis sp. Wet mount preparation 3 Source : www.atlas-protozoa.com Blastocystis sp. Iodine stain

4. Prevalence in developing countries range between 30 to 50 percent Prevalence in developed countries range between 1.5 to 10 percent Prevalence differ between communities and studied hosts 4 Stenzel DJ, Boreham PF. Blastocystis hominis revisited. Clin Microbiol Rev. 1996 Oct;9(4):563-84.

5. Role of pathogenicity in many studies are discordant Clinical manifestations range from asymptomatic to chronic GI symptoms Blastocystis sp. infection may be associated with poor nutritional status in children (Manganelli et.al. 2012) 5

6. In Thailand, the prevalence of Blastocystis carriage in various groups is as high as 10–40% 6 StudyResearch arean% Warunee et.al. (2007) Nakhon Prathom Cental Thailand 19206.2 Yaicharoen et.al.(2006) Nakhon Pathom Central Thailand 81413.51 Leelayoova et.al.(2008) Chonburi Central Thailand 67518.9 Ratanapo et.al.(2008) Chacheongsao Central Thailand 5318.1

7. To clarify the prevalence and associated factors of Blastocystis sp. among primary school students in rural community of central Thailand. 7

8. Cross-sectional study 8

9. Cluster random sampling 9 Primary school in Takradan, Sanam Chai Khet district, Chachoengsao Province Primary school in Takradan, Sanam Chai Khet district, Chachoengsao Province 3 3 2 2 1 1 12... Total survey in 4 selected primary schools

10. Risk factors Outcome 10 Questionnaires Demographic data Risk behaviors Animal & livestock contact Questionnaires Demographic data Risk behaviors Animal & livestock contact Stool examination

11. Blastocystis sp. detection Culture for Blastocystis sp. Intestinal parasite Wet smear preparation Kato-Katz technique formalin-ethyl acetate concentration Agar plate culture method 11 Prevalence of Blastocystis sp. Prevalence of Blastocystis sp. Prevalence of other intestinal parasites Prevalence of other intestinal parasites

12. Chi-square test for categorical variables Logistic regression method using SPSS version 22 Adjusted Odds ratios (OR) and 95% confidence intervals (CI) for risk factors for Blastocystis sp. were estimated by multivariate logistic regression. 12

13. Reviewed and approved by the Institutional Review Board (IRB) of the Royal Thai Army Medical Department. The informed consents and assent were obtained from all participants. Those who diagnosed as parasitic infection were treated with proper treatment. 13

14. 14 Estimated study population 778 cases Questionnaires738 cases (98.1%) Stool specimens501 cases (66.6%) Questionnaires738 cases (98.1%) Stool specimens501 cases (66.6%) 752 cases Matched cases 497 cases Resign, Transfer

15. Characteristicsn(%) Gender Male 227(45.7) Female 270(54.3) Schools School A 189(38.0) School B 55(11.1) School C 52(10.5) School D 201(40.4) 15

16. 16

17. Characteristicsn(%) Address Village 11 79(17.3) Village 15 157(34.4) Village 16 51(11.2) Village 18 67(14.6) Village 19 103(22.5) 17

18. Characteristicsn(%) Religion Buddhism454(92.1) Christianity38(7.7) Islam1(0.2) History of parasitic infection No350(79.9) Yes88(20.1) History of taking antiparasitic drug No189(39.2) Yes293(60.8) 18

19. ParasitePositive finding in feces*% Blastocystis sp.6412.8 Giardia duodenalis71.4 Entamoeba coli51.0 Opisthorchis viverrini40.8 Enterobius vermicularis30.6 Strongyloides stercoralis20.4 Sarcocystis spp.10.2 Trichuris trichiura10.2 Endolimax nana10.2 Chilomastix spp.10.2 Trichomonas hominis10.2 Table 2 – Prevalence of parasitic infection (n=501) 19

20. Adjusted odds ratio 95%CIp-value School School D1 School B4.361.83-10.390.001 School C2.891.10-7.640.032 School A2.201.06-4.540.033 Table 3 - Multivariate analysis of associated factors of Blastocystis infection* *Multivariated analysis adjusted for school, livestock, drinking water and processed water 20

21. Adjusted odds ratio 95%CIp-value Livestock No1 Yes1.60.88-2.920.12 Drinking water Commercial bottle water1 River, well, rain1.40.54-3.790.48 Processed water Yes (boiled, filtered)1 No0.80.48-1.470.53 Table 3 - Multivariate analysis of associated factors of Blastocystis infection* *Multivariated analysis adjusted for school, livestock, drinking water and processed water 21

22. Our study showed that school was an associated factor for Blastocystis infection A few studies showed that Blastocystis infection was associated with untreated drinking water (Leelayoova et al., 2008; Leelayoova et al., 2004; Taamasri P et al., 2000) 22

23. The source of drinking water of each school might be a associated factor of Blastocystis infection Drinking water from each schools was collected to identify Blastocystis sp. contamination. 23

24. 24 Drinking water School D Drinking water School C

25. 25 Drinking water School A Drinking water School B

26. Blastocystis infection has been speculated as a zoonotic parasitic infection. Similar subtype of Blastocystis sp. was detected in both human and dog living in same house in this community (Parker et al., 2007). 26

27. However, the association between Blastocystis infection and zoonotic transmission was not identified in this study. Helminthic infections were less common which may be due to health promotion,education and annual mass chemotherapy. 27

28. Most common parasitic infection in this community is Blastocystis sp. (12.8%) Associated factor of having Blastocystis infection is being in different schools. 28

29. We gratefully acknowledge support for Department of Military and Community Medicine Department of Parasitology Phramongkutklao Research Fund Local village health volunteer Baan Nanagm village All participants for their help in this research 29

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