Abstract
The objective was to assess the association of enteric pathogens in diarrheal disease in a remote rural area in Thailand. Stool specimens were collected from 236 children aged 3 months to 5 years with acute diarrhea (cases) and from 236 asymptomatic controls. Standard microbiologic methods, and enzyme immunoassay for viral pathogens, Giardia, and Cryptosporidium, were used to identify enteric pathogens with susceptibility testing by disk diffusion. Campylobacter, Plesiomonas, Salmonella, and enterotoxigenic Escherichia coli were commonly isolated from cases and controls (22% versus 25%, 10% versus 11%, 6% versus 9%, and 10% versus 6%, respectively). Only Shigella, rotavirus, and adenovirus were identified significantly more frequently in cases than controls (9% versus 0%, 18% versus 3%, and 16% versus 2%, respectively), whereas Giardia lamblia was detected less often in cases than controls. Most pre-school children were infested with enteric pathogens; laboratory-based studies are important to understand the epidemiology of enteric pathogens in remote areas among marginal populations.
Introduction
With over 1.8 million children under 5 years of age dying of diarrheal disease, accounting for 19% of all childhood deaths,1 acute diarrheal disease is a major cause of morbidity and mortality. The mortality of diarrheal disease has declined substantially from a median of annual death of 4.6 million reported in 19822 to 3.0 million and 2.5 million reported in 19923 and 2003,4 respectively. Because 78% of childhood mortality in developing countries occurred in World Health Organization (WHO) African and southeast Asia regions,1 it is vital to gain knowledge of the etiologic and epidemiologic features of diarrheal diseases in that area to make it possible to devise diarrheal disease-specific therapeutic measures and control strategies, most prominent of which is the development of a vaccine that could save millions of lives. The capability to detect an etiologic agent is unfortunately lacking in remote rural areas in many parts of the world where diarrheal disease is most prevalent and where most of the mortality occurs.
In this year-long study of diarrheal disease conducted between October 16, 2001 and October 22, 2002, the researchers established a field microbiology laboratory at the Kwai River Christian Hospital (KRCH) in a rural community in western Thailand on the Thai–Myanmar border to obtain stool specimens to describe and compare the distribution of enteric pathogens as well as the antimicrobial susceptibility pattern among pre-school children with and without diarrhea.
Methods
Study site.
This study was conducted from October 2001 to October 2002 in Kanchanaburi province, Sangkhlaburi district, Nongloo subdistrict, located 365 km northwest of Bangkok, Thailand on the Thai–Myanmar border. In this district, six villages are located within a 9-km radius of KRCH and share a main market. Stool samples were collected from pre-schoolers seen at KRCH or one of three nearby health centers.
Enrollment and specimen and data collection.
This study was approved by the Ethical Review Committee of Research in Human Subjects, Ministry of Public Health, Nonthaburi, Thailand and the Human Subjects Research Review Board, US Army Medical Research and Material Command, Fort Detrick, MD.
After obtaining informed consent from a parent or guardian, a stool sample was collected from children aged 3 months to 5 years who came to the hospital or one of the three nearby health centers with complaints of acute diarrhea. Specimens were collected from age-matched children (±3 months) who came to the hospital or health centers for reasons other than diarrhea within 1 week after the case was enrolled. Controls had no history of diarrhea for the 2 weeks before enrollment. Information on demographic and historical clinical data were obtained from parents or caregivers of both cases and controls and recorded in questionnaires.
Specimen processing and examination.
Fresh stool was inoculated onsite onto MacConkey (MC), Hektoen Enteric (HE), thiosulfate citrate bile salts sucrose (TCBS), and modified semi-solid Rappaport Vassiliadis (MSRV) agars and into four enrichment broths (0.5% alkaline peptone water [APW], selenite broth [SB], buffered peptone water [BPW], and modified Doyle). Then, they were incubated at 37°C overnight, except for MSRV, which was incubated at 42°C. Millipore-filtered (0.65 µm) stool suspension was inoculated on Brucella agar with 5% sheep blood (BAP), and stool suspension was inoculated on modified charcoal-cefoperazone deoxycholate agar (mCCDA) for detection of Campylobacter; both were incubated under microaerophilic conditions (5% O2, 10% CO2, and 85% N2) at 37°C for at least 48 hours. After overnight incubation of enrichment broths, aliquots of APW were inoculated to TCBS; aliquots of BPW and SB were inoculated to MC, HE, and MSRV; and aliquots of Doyle were inoculated to BAP (after millipore filtration) and mCCDA. Subculture plates were incubated as previously described. Campylobacter, Salmonella, Shigella, Plesiomonas, Aeromonas, Vibrio, and Arcobacter butzleri were subsequently identified by standard microbiologic methods at Armed Forces Research Institute of Medical Sciences (AFRIMS) in Bangkok, Thailand. Campylobacter isolates were identified at species level by using conventional phenotypic tests for Campylobacter.5
For diarrheagenic Escherichia coli identification, five lactose-fermenting and up to five non–lactose-fermenting E. coli colonies isolated from each child were spotted on nylon membranes N+ (GE Healthcare, Buckinghamshire, UK). The membranes were processed for hybridization assay with specific Digoxigenin-labeled DNA polynucleotide probes. A heat-labile toxin (LT) and two heat-stable toxin (STIa and STIb) probes were used to identify Enterotoxigenic E. coli (ETEC).6,7 Invasion-associated locus (ial) probe was used to identify Enteroinvasive E. coli (EIEC).7 Shiga-like toxin I and II (SLTI and SLT II) probes were used to identify Shiga-like toxin-producing E. coli (STEC).7 Effacing attachment (EAE), Enteroadherent factor (EAF), and bundle-forming pilus A (bfpA) probes were used to identify Enteropathogenic E. coli (EPEC).8,9 Three reference E. coli strains derived from plasmid harboring enterotoxin genes, pEWD299 (LT), pDAS100 (STIa), and pDAS101 (STIb), were included as positive controls for ETEC. Six reference E. coli strains harboring virulence plasmid or virulence DNA fragments, 933J (SLTI), 933W (SLTII), AS-04-1 (EAE), pMSD 207 (BfpA), pMAR-22 (EAF), and E. coli No. 2 (EIEC), were included as positive controls for the STEC, EPEC, and EIEC, respectively. E. coli K-12 Xac was used as a negative control. Digoxigenin-labeling and hybridization assay were carried out according to manufacturer instruction (Roche Diagnostics, Indianapolis, IN).
Rotavirus, astrovirus, and adenovirus were identified by enzyme immunoassay (EIA) test kits (RIDASCREEN; R-Biopharm, Damstadt, Germany). Giardia lamblia and Cryptosporidium were also detected by EIA kits (ProSpecT; Remel, Lenexa, KS).
Susceptibility testing.
Antibiotic susceptibility testing was performed by a standard disk diffusion technique on all identified bacterial isolates. In the absence of Clinical and Laboratory Standards Institute (CLSI, Wayne, PA) definitive standards for interpreting Campylobacter susceptibility results, breakpoints for the family Enterobacteriaceae were used. For Campylobacter and other bacterial enteropathogens, azithromycin interpretive standards as published by the disk manufacturer for Staphylococcus spp. were used (BBL package insert; Becton-Dickinson, Sparks, MD).
Statistical analysis.
Statistical analysis was performed by using a McNemar test on the case-control data. A P value of < 0.05 was considered significant.
Results
From October 16, 2001 to October 22, 2002, stool specimens were collected from a total of 472 pre-school children (233 males and 239 females); 236 presented with diarrhea (cases), and 236 were asymptomatic (controls). The median age for cases was 15 months and 14 months for controls; 78% of cases and 79% of controls were less than or equal to 2 years of age, and 53% of cases and 46% of controls were male. Eighty-seven percent (205/236) of controls were children attending a well-child clinic for check-up or routine immunization. The remaining controls were children without diarrhea but with other medical problems. Two percent of controls had received antibiotics by report before the enrollment. Among cases, the mean duration of diarrhea was 48.2 hours, and 69% and 35% were reported to have had a history of fever and vomiting, respectively.
The most common organisms identified in diarrhea cases among these pre-school children were Campylobacter spp. (22%), rotavirus (18%), and adenovirus (16%) (Table 1). Although Shigella, rotavirus, and adenovirus were detected significantly more often from diarrhea cases as opposed to asymptomatic controls (9% versus 0%, 18% versus 3%, and 16% versus 2%, respectively), Campylobacter, Salmonella, Plesiomonas, G. lamblia, and Cryptosporidium were identified less often in case patients than in controls (22% versus 25%, 6% versus 9%, 10% versus 11%, 15% versus 23%, and 2% versus 5%, respectively). Of these, G. lamblia was the only enteropathogen detected significantly more often in controls than cases (P < 0.05). ETEC and EPEC were detected nearly as often in controls as in cases (6% versus 10% and 14% versus 15%, respectively). More than one organism was identified in 82 of 236 (35%) diarrhea cases and 60 of 236 (25%) of controls. No Vibrio species or STEC was detected in this study. No enteric pathogens were identified in 31% and 32% of cases and controls, respectively (Table 1).
Table 1.
Number and percentage of isolation of enteropathogens in children with diarrhea and non-diarrhea controls in Sangkhlaburi, Thailand
| Cases (N = 236) | Controls (N = 236) | P value* | |
|---|---|---|---|
| Campylobacter | 51 (22%) | 59 (25%) | NS |
| Salmonella | 15 (6%) | 21 (9%) | NS |
| Shigella* | 21 (9%) | 1 (0.4%) | < 0.0001 |
| Enterotoxigenic E. coli | 20/208 (10%) | 13/203 (6%) | NS |
| Enteroinvasive E. coli | 4/219 (2%) | 0/219 (0%) | – |
| Enteropathogenic E. coli | 33/219 (15%) | 31/219 (14%) | NS |
| Plesiomonas | 23 (10%) | 27 (11%) | NS |
| Aeromonas | 6 (3%) | 8 (3%) | NS |
| Arcobacter butzleri | 2 (1%) | 2 (1%) | NS |
| Rotavirus | 41/232 (18%) | 7 (3%) | < 0.0001 |
| Astrovirus | 7/207 (3%) | 3/227 (1%) | NS |
| Adenovirus | 33/207 (16%) | 4/227 (2%) | < 0.0001 |
| Giardia lamblia | 31/207 (15%) | 53/227 (23%) | 0.04 |
| Cryptosporidium | 4/207 (2%) | 12/227 (5%) | NS |
| No pathogens identified | 72 (31%) | 76 (32%) | NS |
Analysis for matched-pair case-control data using McNemar test with significant P value at < 0.05; NS = not significant.
Among 57 Campylobacter isolates from 51 cases and 67 isolates from 59 controls, 70% versus 54%, 12% versus 24%, and 16% versus 22% were C. jejuni, C. coli, and C. upsalienses, respectively. Eighty-six percent (18/21) of Shigella isolates from cases were S. flexneri, and the rest were S. sonnei. The most common serotype was S. flexneri 3a, identified in 13 of 21 (62%) cases. The one Shigella isolate from one control was S. dysenteriae type 4. Of the 23 ETEC isolates from 20 cases, 48% had ST, 17% had LT, and 35% had LT and ST. Of the 13 ETEC isolates from 13 controls, 31% had ST, 54% had LT, and 15% had LT and ST.
The age-specific prevalence of identified organisms is given in Table 2. There was no significant difference in prevalence in cases compared with controls for all age groups for Campylobacter, Salmonella, Plesiomonas, and EPEC. Rotavirus and adenovirus were most commonly found in children less than 12 months old with diarrhea (20%), and controls clearly had low recovery (0–6%). Shigella was most often (23%) found in the case children over 2 years of age with diarrhea, whereas none was found in controls. G. lamblia was more commonly detected among controls than in cases, and interestingly, prevalence increased with age.
Table 2.
Number and percentage of pathogens isolated from children by age in Sangkhlaburi, Thailand
| Age | 3–12 months | 13–24 months | 25–59 months | |||
|---|---|---|---|---|---|---|
| Cases (N = 98) | Controls (N = 109) | Cases (N = 86) | Controls (N = 78) | Cases (N = 52) | Controls (N = 49) | |
| Campylobacter | 21 (21%) | 27 (25%) | 21 (24%) | 24 (31%) | 9 (17%) | 8 (16%) |
| Salmonella | 6 (6%) | 6 (6%) | 4 (5%) | 9 (12%) | 5 (10%) | 6 (12%) |
| Shigella | 3 (3%) | 1 (1%) | 6 (7%) | 0 (0%) | 12 (23%) | 0 (0%) |
| Enterotoxigenic E. coli | 6/84 (7%) | 0/97 (0%) | 6/78 (8%) | 6/65 (9%) | 8/47 (17%) | 7/41 (17%) |
| Enteropathogenic E. coli | 12/91 (13%) | 19/105 (18%) | 13/80 (16%) | 8/71 (11%) | 8/48 (17%) | 4/43 (9%) |
| Plesiomonas | 5 (5%) | 9 (8%) | 5 (6%) | 9 (12%) | 13 (25%) | 9 (18%) |
| Rotavirus | 19/97 (20%) | 7 (6%) | 14/85 (17%) | 0 (0%) | 8/50 (16%) | 0 (0%) |
| Adenovirus | 18/85 (21%) | 3/103 (3%) | 8/79 (10%) | 0/77 (0%) | 7/43 (16%) | 1/47 (2%) |
| Giardia lamblia | 5/85 (6%) | 10/103 (10%) | 12/79 (15%) | 28/77 (36%) | 14/43 (33%) | 15/47 (32%) |
| No pathogens identified | 35 (36%) | 39 (36%) | 27 (31%) | 25 (32%) | 10 (19%) | 12 (25%) |
The pattern of antibiotic resistance for bacterial pathogens isolated from cases and controls is shown in Table 3; because the pattern differed little in cases and controls, data were not analyzed separately. Ciprofloxacin was very effective against all bacterial pathogens except Campylobacter, for which resistance was detected in 38% of isolates. No resistance to azithromycin was observed among Campylobacter isolates. Nalidixic acid resistance was observed in 18% of Salmonella, 46% of Campylobacter, 12% of Plesiomonas, and 0% of Shigella or ETEC isolates (Table 3).
Table 3.
Number and percentage of antibiotic resistance of bacterial pathogens isolated from children in Sangkhlaburi, Thailand
| Pathogen | Salmonella (N = 38) | Shigella (N = 22) | Campylobacter(N = 126) | Plesiomonas (N = 50) | ETEC* (N = 44) |
|---|---|---|---|---|---|
| Ampicillin | 11 (29%) | 9 (41%) | 14 (11%) | 13 (26%) | 24 (55%) |
| TMP-SXT† | 8 (21%) | 21 (95%) | 56 (44%) | 4 (8%) | 18 (41%) |
| Tetracycline | 19 (50%) | 21 (95%) | 27 (22%) | 12 (24%) | 30 (68%) |
| Nalidixic acid | 7 (18%) | 0 (0%) | 58 (46%) | 6 (12%) | 0 (0%) |
| Ciprofloxacin | 0 (0%) | 0 (0%) | 48 (38%) | 0 (0%) | 0 (0%) |
| Azithromycin | 2 (5%) | 1 (5%) | 0 (0%) | 0 (0%) | 2 (5%) |
Enterotoxigenic E. coli.
Trimethoprim-sulfamethoxazole.
Discussion
Determination of the true etiological role of enteric pathogens detected in children with diarrhea in a developing country is difficult, because enteric pathogens are also frequently identified in apparently healthy children. Moreover, it is not uncommon to find more than one pathogen in one child, and therefore, it is rarely possible to define which is causing disease. Asymptomatic infections are widely reported in developing countries in both community and clinic-based studies.10–16 Acquired immunity from frequent previous exposures, long-term convalescent shedding of the organism, or exposure to insufficient amounts of an organism to cause disease are the main explanations for asymptomatic carriers.15,17–19 Several studies have reported a high prevalence of Salmonella, Giardia, and Campylobacter in children without diarrhea in developing countries.16,20,21 Recent data from Vietnam reported 23% of diarrheagenic E. coli in both diarrhea cases and controls.12 The data obtained in this study support those findings, and G. lamblia was detected in a significantly higher proportion of controls than in cases. This was also observed in a case-control study in Bangladesh with no clear explanation.16
The proportions of cases and controls with pathogens identified were similar at approximately 70%. A previous clinic-based study of diarrhea etiology conducted in Bangkok in 1985 reported lower pathogen carriage in controls of 30%. In the same study, Shigella, Campylobacter, Salmonella, ETEC, EIEC, Cryptosporidium, rotavirus, and adenovirus were all found to be causative agents of diarrhea illness.14 Organisms that have been consistently and substantially reported more frequently in children with diarrhea than in controls were ETEC, Shigella, and rotavirus.11,16,21,22 In this study, only four organisms, Shigella, rotavirus, adenovirus, and ETEC (in children less than 12 months), were significantly associated with acute diarrheal disease in this pre-school population, but these 4 pathogens accounted for approximately 50% of all cases. Among these, antibiotic administration is required only for children with shigellosis as per WHO treatment guideline; for acute diarrhea, the recommendation is the use of antibiotic only in suspected cases of shigellosis and cholera.23
This draws attention to the potentially unnecessary administration of antibiotics for the treatment of diarrheal disease. This can be problematic, both in terms of economic burden related to cost of medications and healthcare and as a contributor to antibiotic resistance. For example, Shigella isolates had a high prevalence of resistance to trimethoprim-sulfamethoxazole (TMP-SXT), the antibiotic previously used for treatment of diarrheal disease in Thailand. This study also observed resistance to nalidixic acid among all bacterial species, although ciprofloxacin resistance was detected only in Campylobacter isolates (38%). A high prevalence of nalidixic acid and fluoroquinolone-resistant Campylobacter has been well-documented in Thailand.24–26 Resistance of Campylobacter isolates to nalidixic acid increased significantly during 1991–2000, with isolates resistant to both nalidixic acid and ciprofloxacin observed significantly more frequently in urban than in rural settings.24 Ongoing antimicrobial surveillance may permit more effective therapy in remote areas.
In conclusion, this study, undertaken in a remote area of Thailand, found the major causes of acute diarrhea in children less than 5 years of age to be rotavirus, adenovirus, and Shigella spp. Although a high proportion of mixed infections and asymptomatic carriers were reported, similar to other case-control studies in developing countries, 70% of pre-school children in our study were infested with at least one potential enteric pathogen, a greater number than expected. Laboratory-based studies that include non-diarrhea controls are important to gain a more complete understanding of the epidemiology and distribution of enteric pathogens to enable development of effective programs aimed at disease prevention and health promotion targeting remote areas and marginal populations.
Acknowledgments
We would like to thank staff members of Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences for their support on laboratory assays and data management and staff members of the Kwai River Christian Hospital for their assistance on subject enrollment, specimen processing, and logistics.
Footnotes
Financial support: This work was supported by Armed Forces Health Surveillance Center–Global Emerging Infections Surveillance and Response Systems, Washington, DC.
Authors' addresses: Ladaporn Bodhidatta, Siriporn Sornsakrin, Apichai Srijan, Oralak Serichantalergs, and Carl J. Mason, Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, Phyathai, Bangkok, Thailand, E-mails: ladapornb@afrims.org, siriporns@afrims.org, apichais@afrims.org, oralaks@afrims.org, and carl.mason@afrims.org. Philip McDaniel, Kwai River Christian Hospital, Sangklaburi, Kanchanaburi, E-mail: krchphil@gmail.com.
Reprint requests: Ladaporn Bodhidatta, Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences (AFRIMS), 315/6 Rajvithi Road, Phyathai, Bangkok 10400, Thailand, E-mail: ladapornb@afrims.org.
References
- 1.Boschi-Pinto C, Velebit L, Shibuya K. Estimating child mortality due to diarrhoea in developing countries. Bull World Health Organ. 2008;86:710–717. doi: 10.2471/BLT.07.050054. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Snyder JD, Merson MH. The magnitude of the global problem of acute diarrhoeal disease: a review of active surveillance data. Bull World Health Organ. 1982;60:605–613. [PMC free article] [PubMed] [Google Scholar]
- 3.Bern C, Martines J, de Zoysa I, Glass RI. The magnitude of the global problem of diarrhoeal disease: a ten-year update. Bull World Health Organ. 1992;70:705–714. [PMC free article] [PubMed] [Google Scholar]
- 4.Kosek M, Bern C, Guerrant RL. The global burden of diarrhoeal disease, as estimated from studies published between 1992 and 2000. Bull World Health Organ. 2003;81:197–204. [PMC free article] [PubMed] [Google Scholar]
- 5.Vandamme P. In: Campylobacter. 2nd ed. Nachamkin I, Blaser MJ, editors. Washington, DC: ASM Press; 2000. pp. 3–26. (Taxonomy of the family Campylobacteraceae). [Google Scholar]
- 6.Sommerfelt H, Kalland KH, Raj P, Moseley SL, Bhan MK, Bjorvatn B. Cloned polynucleotide and synthetic oligonucleotide probes used in colony hybridization are equally efficient in the identification of enterotoxigenic Escherichia coli. J Clin Microbiol. 1988;26:2275–2278. doi: 10.1128/jcm.26.11.2275-2278.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Echeverria P, Seriwatana J, Sethabutr O, Chatkaeomorakot A. In: Gene Probes for Bacteria. Macaro AJL, Conway de Macario E, editors. San Diego, CA: Academic Press Inc; 1990. pp. 95–141. (Detection of diarrheagenic Escherichia coli using nucleotide probes). [Google Scholar]
- 8.Nataro JP, Baldini MM, Kaper JB, Black RE, Bravo N, Levine MM. Detection of an adherence factor of enteropathogenic Escherichia coli with a DNA probe. J Infect Dis. 1985;152:560–565. doi: 10.1093/infdis/152.3.560. [DOI] [PubMed] [Google Scholar]
- 9.Giron JA, Ho AS, Schoolnik GK. An inducible bundle-forming pilus of enteropathogenic Escherichia coli. Science. 1991;254:710–713. doi: 10.1126/science.1683004. [DOI] [PubMed] [Google Scholar]
- 10.Schorling JB, Wanke CA, Schorling SK, McAuliffe JF, de Souza MA, Guerrant RL. A prospective study of persistent diarrhea among children in an urban Brazilian slum. Patterns of occurrence and etiologic agents. Am J Epidemiol. 1990;132:144–156. doi: 10.1093/oxfordjournals.aje.a115626. [DOI] [PubMed] [Google Scholar]
- 11.Huilan S, Zhen LG, Mathan MM, Mathew MM, Olarte J, Espejo R, Khin Maung U, Ghafoor MA, Khan MA, Sami Z. Etiology of acute diarrhoea among children in developing countries: a multicentre study in five countries. Bull World Health Organ. 1991;69:549–555. [PMC free article] [PubMed] [Google Scholar]
- 12.Hien BT, Trang do T, Scheutz F, Cam PD, Molbak K, Dalsgaard A. Diarrhoeagenic Escherichia coli and other causes of childhood diarrhoea: a case-control study in children living in a wastewater-use area in Hanoi, Vietnam. J Med Microbiol. 2007;56:1086–1096. doi: 10.1099/jmm.0.47093-0. [DOI] [PubMed] [Google Scholar]
- 13.Guerrant RL, Kirchhoff LV, Shields DS, Nations MK, Leslie J, de Sousa MA, Araujo JG, Correia LL, Sauer KT, McClelland KE. Prospective study of diarrheal illnesses in northeastern Brazil: patterns of disease, nutritional impact, etiologies, and risk factors. J Infect Dis. 1983;148:986–997. doi: 10.1093/infdis/148.6.986. [DOI] [PubMed] [Google Scholar]
- 14.Echeverria P, Taylor DN, Lexsomboon U, Bhaibulaya M, Blacklow NR, Tamura K, Sakazaki R. Case-control study of endemic diarrheal disease in Thai children. J Infect Dis. 1989;159:543–548. doi: 10.1093/infdis/159.3.543. [DOI] [PubMed] [Google Scholar]
- 15.Black RE, Lopez de Romana G, Brown KH, Bravo N, Bazalar OG, Kanashiro HC. Incidence and etiology of infantile diarrhea and major routes of transmission in Huascar, Peru. Am J Epidemiol. 1989;129:785–799. doi: 10.1093/oxfordjournals.aje.a115193. [DOI] [PubMed] [Google Scholar]
- 16.Albert MJ, Faruque AS, Faruque SM, Sack RB, Mahalanabis D. Case-control study of enteropathogens associated with childhood diarrhea in Dhaka, Bangladesh. J Clin Microbiol. 1999;37:3458–3464. doi: 10.1128/jcm.37.11.3458-3464.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Levine MM, Kaper JB, Black RE, Clements ML. New knowledge on pathogenesis of bacterial enteric infections as applied to vaccine development. Microbiol Rev. 1983;47:510–550. doi: 10.1128/mr.47.4.510-550.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Cravioto A, Reyes RE, Trujillo F, Uribe F, Navarro A, De La Roca JM, Hernandez JM, Perez G, Vazquez V. Risk of diarrhea during the first year of life associated with initial and subsequent colonization by specific enteropathogens. Am J Epidemiol. 1990;131:886–904. doi: 10.1093/oxfordjournals.aje.a115579. [DOI] [PubMed] [Google Scholar]
- 19.Black RE, Brown KH, Becker S, Alim AR, Huq I. Longitudinal studies of infectious diseases and physical growth of children in rural Bangladesh. II. Incidence of diarrhea and association with known pathogens. Am J Epidemiol. 1982;115:315–324. doi: 10.1093/oxfordjournals.aje.a113308. [DOI] [PubMed] [Google Scholar]
- 20.Gilman RH, Marquis GS, Miranda E, Vestegui M, Martinez H. Rapid reinfection by Giardia lamblia after treatment in a hyperendemic Third World community. Lancet. 1988;1:343–345. doi: 10.1016/s0140-6736(88)91131-2. [DOI] [PubMed] [Google Scholar]
- 21.Black RE. In: Infectious Disease Epidemiology: Theory and Practice. Nelson K, Williams CM, Graham N, editors. Gaithersburg, MD: Aspen Publishers Inc; 2000. pp. 497–517. (Diarrheal disease). [Google Scholar]
- 22.Vu Nguyen T, Le Van P, Le Huy C, Nguyen Gia K, Weintraub A. Etiology and epidemiology of diarrhea in children in Hanoi, Vietnam. Int J Infect Dis. 2006;10:298–308. doi: 10.1016/j.ijid.2005.05.009. [DOI] [PubMed] [Google Scholar]
- 23.World Health Organization The Treatment of Diarrhoea: A Manual for Physicians and Other Senior Health Workers. 2005. http://whqlibdoc.who.int/publications/2005/9241593180.pdf Available at: Accessed August 1, 2010.
- 24.Serichantalergs O, Dalsgaard A, Bodhidatta L, Krasaesub S, Pitarangsi C, Srijan A, Mason CJ. Emerging fluoroquinolone and macrolide resistance of Campylobacter jejuni and Campylobacter coli isolates and their serotypes in Thai children from 1991 to 2000. Epidemiol Infect. 2007;135:1299–1306. doi: 10.1017/S0950268807008096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Isenbarger DW, Hoge CW, Srijan A, Pitarangsi C, Vithayasai N, Bodhidatta L, Hickey KW, Cam PD. Comparative antibiotic resistance of diarrheal pathogens from Vietnam and Thailand, 1996–1999. Emerg Infect Dis. 2002;8:175–180. doi: 10.3201/eid0802.010145. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Hoge CW, Gambel JM, Srijan A, Pitarangsi C, Echeverria P. Trends in antibiotic resistance among diarrheal pathogens isolated in Thailand over 15 years. Clin Infect Dis. 1998;26:341–345. doi: 10.1086/516303. [DOI] [PubMed] [Google Scholar]