HIGH PREVALENCE OF PROTOZOAN INFECTIONS IN THAILAND PREVALENCE OF INTESTINAL PROTOZOAN INFECTIONS AMONG CHILDREN IN THAILAND: A LARGE-SCALE SCREENING AND COMPARATIVE STUDY OF THREE STANDARD DETECTION METHODS Vivornpun Sanprasert1,2, Nittaya Srichaipon2, Uthaitip Bunkasem1,2, Siriporn Srirungruang1,2 and Surang Nuchprayoon1,2 1Department of Parasitology, 2Lymphatic Filariasis and Tropical Medicine Research Unit, Chulalongkorn Medical Research Center, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand Abstract. A significant impact of intestinal parasitic infections on public health has mostly been neglected. Parasitic infections are one of risk factors for mal- nutrition in children. In this study, a large-scale screening of intestinal parasitic infections among children in 16 schools in 6 regions of Thailand was performed. In addition, we compared sensitivity of methods currently employed for detec- tion of intestinal parasitic infection. Fecal samples collected from 1,909 students were examined for intestinal parasites by simple smear, formalin-ethyl acetate concentration (FECT), and Locke-egg-serum (LES) medium culture methods. Seven hundred and thirteen samples were infected with at least one intestinal parasite. The highest prevalence (82.8%) was found in Kanchanaburi Province, western Thailand. Blastocystis spp was the most common (32.8%) parasite, fol- lowed by Giardia duodenalis (4.2%), Ascaris lumbricoides (3.6%), hookworms (1.6%), Entamoeba histolytica (0.7%), Trichuris trichiura (0.5%), Enterobius vermicularis (0.5%), Strongyloides stercoralis (0.4%), minute intestinal flukes (0.2%), and Taenia spp (0.1%). Mixed parasitic infections were found in 121 students. In a comparative study, we found that FECT was more sensitive (74.0%) than simple smear (55.0%) method for detecting helminths. However, sensitivity of these two methods is not significantly different for protozoan detection (31.2% by simple smear and 33.5% by FECT). LES culture technique was the most sensitive method (77.5%) for detect- ing Blastocystis spp. Our results indicate a high prevalence of intestinal parasite infection among Thai students. More sensitive methods should be developed for a large-scale screening of intestinal protozoan infection. Keywords: Blastocystis spp, intestinal parasite, school-age student, Thailand INTRODUCTION Correspondence: Surang Nuchprayoon, De- partment of Parasitology, Faculty of Medicine, Parasitic infection remains a major Chulalongkorn University, Bangkok 10330, public health problem worldwide, partic- Thailand. ularly in developing countries. However, Tel: +66 (0) 2256 4387, +66 (0) 2252 5944; Fax: the impact of these infections on public +66 (0) 2252 4963 health has been mostly ignored. To date, a E-mail: [email protected] national prevalence of intestinal parasites Vol 47 No. 6 November 2016 1123 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH in Thailand has not been reported. Most Walker et al, 2007; Jardim-Botelho et al, studies report prevalence in specific areas. 2008; Yentur Doni et al, 2015). In Thailand, In 2009, the national survey of helminthia- the studies of intestinal parasite infec- sis in Thailand showed high prevalence tions usually report only the prevalence of parasitic infection (18.1%) in Thai of certain parasites (eg, soil-transmitted people (Wongsaroj et al, 2012). Prevalence helminths) (Anantaphruti et al, 2008), or in of intestinal parasitic infections varies a selected group of children in certain areas from one area to another depending on (eg, in orphanages and in students in cen- the degree of personal and community tral region of the country) (Saksirisampant hygiene, sanitation and climatic factors et al, 2003, 2006; Ngrenngarmlert et al, 2007). (Soriano et al, 2001; Manganelli et al, 2012; Effective diagnosis will assist in a bet- Wongsaroj et al, 2012; Boonjaraspinyo et al, ter surveillance of intestinal parasitic infec- 2013). Prevalence of intestinal parasitic tions. Early diagnosis is needed to reduce infections among Thai patients in urban and prevent transmission. There are many areas who visited the outpatient unit of alternative methods to detect parasitic King Chulalongkorn Memorial Hospi- infections, including molecular and im- tal, Bangkok is 6.1-8.94% (Nuchprayoon munological assays. However, these tech- et al, 2002; Saksirisampant et al, 2002). niques are time-consuming and require This prevalence is lower than the aver- expensive reagents, instruments, as well as age prevalence (34-72%) in remote areas technical expertise. Thus, microscopic ex- of Thailand (Triteeraprapab et al, 1997; amination remains the routine method for Triteeraprapab and Nuchprayoon, 1998; laboratory diagnosis of intestinal parasitic Triteeraprapab et al, 1999; Nuchprayoon infection. The current routine techniques et al, 2009). This may be due to the fact for screening intestinal parasitic infec- that people in remote areas usually have tion are simple smear and formalin-ethyl cultural food beliefs, poor dietary habit, acetate concentration (FECT). The simple poor sanitation and hygiene as well as smear technique is easy to perform but its difficulty in gaining access to good health sensitivity is low, leading to misdiagnosis. information and healthcare services. Sensitivity of FECT is higher than simple Parasitic infection in children are still smear technique for diagnosis of intestinal common, even in developed countries. helminth infection (Saksirisampant et al, Globally, over 1 billion people are esti- 2003; Nuchprayoon et al, 2009; Hailu and mated to be infected with at least one type Abera, 2015). of intestinal helminths, with the highest In this study, a large-scale survey prevalence in school-age children (de Silva of the prevalence of intestinal parasitic et al, 2003). Parasitic infection can lead to infection in school-age children was per- malabsorption and chronic blood loss in formed in 6 regions of Thailand. In addi- children, with long-term effects on their tion, a comparative study was conducted physical (height and weight) and cogni- among different techniques for parasite tive development. Malnutrition is com- identification. mon in school-age children in developing countries. Parasitic infection is one of risk MATERIALS AND METHODS factors for malnutrition, poor psychomo- tor development, growth retardation, and Study areas and test population stunting in children (Casapia et al, 2006; Cross-sectional surveys were per- 1124 Vol 47 No. 6 November 2016 HIGH PREVALENCE OF PROTOZOAN INFECTIONS IN THAILAND parasitic diseases (eg, consumption of well-cooked food, hygienic defecation and no bare-feet be- havior) also were explained to the par- ticipants. Written in- formed consent was obtained from legal guardian of each in- dividual to partici- pate in the study. Stool examination Stool collection containers were dis- tributed to all par- ticipants. In order to avoid contamina- tion, specific precau- Fig 1 - Location of the study areas in the six regions of Thailand. tion and guideline for specimen collec- formed in 16 schools in 7 provinces (Ang tion were explained to all students. Stool Thong, Nakhon Ratchasima, Khon Kaen, samples were stored at room temperature Nan, Chon Buri, Kanchanaburi and Phat- prior to cultivation and stool examina- thalung) located in central, northeastern, tions on the following day at Lymphatic northern, eastern, western, and southern Filariasis and Tropical Medicine Research Thailand (Fig 1). All schools, except those Unit, Department of Parasitology, Faculty in Nakhon Ratchasima Province, are in of Medicine, Chulalongkorn University, rural areas. Schools in Nan and Kanchana- Bangkok. Simple smear, FECT and Boeck buri Provinces are located in mountain and Drbohlav’s Locke-egg-serum (LES) villages and most of students are from medium culture techniques for detec- hill tribes. A number of students in Chon tion of intestinal parasite eggs or larvae Buri and Kanchanaburi Provinces are were performed as described previously migrants from Myanmar. In cooperation (Nuchprayoon et al, 2009). In brief, stool with school directors, 1,909 students aged samples were examined microscopically between 1 to 23 years (mean ± range, 9.9 of simple smears using normal saline ± 4.9 years) were recruited to the study. and iodine preparation. About 2-5 mg The study was approved by the Eth- of each stool specimen was processed by ics Committee of the Faculty of Medicine, FECT method. LES medium culture was Chulalongkorn University, Bangkok (IRB conducted for identification ofBlastocystis no. 396/56). All subjects were well in- sp and Entamoeba histolytica. The presence formed about the health effects and the of intestinal parasite eggs, larvae or cysts danger from intestinal parasitic infection. was determined microscopically. Samples Prevention methods against common were independently examined by two Vol 47 No. 6 November 2016 1125 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Table 1 Prevalence of intestinal parasitic infections among surveyed students in Thailand classified by gender and age groups. Age Number Number of positives Percent prevalence (years) (male, female, unspecified) (male, female, unspecified) (male, female, unspecified) 1-6 278 (145, 133, 0) 79 (43, 36, 0) 28.4 (29.7, 27.1, 0) 7-12 1,193 (551, 642,0) 555 (261, 294, 0) 46.5a (47.4, 45.8, 0) 13-23 403 (207, 196, 0) 71 (29, 42, 0) 17.6 (14.0, 21.4, 0) Not available 35 (0, 0, 35) 8 (0, 0, 8) 22.9 (0, 0, 22.9) Total 1,909 (903, 971, 35) 713 (333, 372, 8) 37.3 (36.9, 38.3, 22.9) aSignificantly higher than