| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
ABSTRACT |
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The main etiology of the diarrhea is related to a wide range of bacteria (such as Campylobacter jejuni, Escherichia coli, Salmonella spp., Vibrio cholerae, Yersinia enterocolitica, and Aeromonas spp.), enteroparasites (Giardia spp., Criptosporidium spp., and Entamoeba histolytica), and viruses (adenovirus, Norwalk virus, and rotavirus).
In many hospitals in developing countries lacking clinical microbiology laboratories, the cause of diarrhea in children is unknown. The seasonality of specific enteropathogens such as rotavirus or some parasites has been reported.4–8
The aim of this study was to determine the prevalence of enteropathogens, including bacteria, virus, and parasites, causing diarrhea among children less than five years old in Ifakara, Tanzania during the dry and rainy seasons.
|
MATERIALS AND METHODS |
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Microorganisms. Whole stool specimens from 348 (172 boys and 176 girls) and 103 (51 boys and 52 girls) children less than five years old who were admitted to St. Francis Hospital in the dry and rainy seasons, respectively, were cultured for E. coli and other bacterial enteropathogens using conventional methods.9 Diarrhea was defined as three or more watery or loose stools in a 24-hour period prior to admission to the hospital. Fresh specimens were examined directly to detect ova and vegetative forms of parasites. The visualized amebic cysts were confirmed by Hiedenhain staining. Stools were examined after concentration by the merthiolate-iodine-formalin technique and were stained with Kinyoun’s carbolfuchsine.10 Rotavirus was detected using an agglutination test (Slidex Rotakit 2; BioMérieux, Marcy l’Etoile, France).
Detection of E. coli virulence factors. The virulence factors associated with diarrheogenic E. coli were detected by a polymerase chain reactgion (PCR) technique. Specific primers were used to detect enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), and verotoxigenic E. coli (VTEC). The conditions used for the PCR technique were those described elsewhere.11 Briefly, one colony of each isolate was suspended in 25 µL of sterile water and boiled for 10 minutes. A 25-µL of reaction mixture containing 20 mM Tris-HCl (pH 8.8), 100 mM KCl, 3.0 mM MgCl 2, 0.1% gelatin, 400 µM dNTPs, and 1 µM of each primer was added, together with 2.5 units of Taq polymerase. The reaction mixture was overlaid with a drop of mineral oil and subjected to the following program: 30 cycles at 95°C for 50 seconds, 55°C for 1.5 minutes, and 72°C for two minutes. The PCR product was detected by electrophoresis on a 2% agarose gel and stained with ethidium bromide.
Statistical analysis. Proportions were compared using the chi-square test.
|
RESULTS |
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Two hundred forty (71.83%) stool samples collected during the dry season and 65 (63.1%) collected during the rainy season showed at least one enteropathogen. The prevalence of the different enteropathogens in each season is shown in Table 1
.
|
Seventy-three (56.2%) of 130 diarrheogenic E. coli isolated in the dry season and 13 (41.8%) of 31 isolated in the rainy season were associated with other enteropathogens. Among diarrheogenic E. coli (Table 2), ETEC were isolated more often during the rainy season (16 of 31, 51.6%) than during the dry season (26 of 130, 20%) (P < 0.0001). Moreover, ETEC with heat-stable toxin (ETEC-ST) was detected more often in comparison with ETEC with heat-labile toxin (ETEC-LT) and ETEC-LT/ST.
|
The proportion of Shigella spp. isolated during the dry season was significantly higher (24.14%) than that isolated during the rainy season (P = 0.012). The high proportion of G. lamblia isolated during the rainy season (14.5%) was significantly higher than that isolated during the dry season (1.15%) (P < 0.00001), while the proportion of rotavirus (23.56%) isolated during the dry season was significantly higher than that isolated during the rainy season (P < 0.00001).
|
DISCUSSION |
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Overall, the proportion of diarrheogenic E. coli in both seasons was high, which is consistent with previous reports from developing countries.2,13 However, in some cases, differences were found in comparison with reports in the literature.14–16 Our results differ with those analyzing the prevalence of ETEC in children from Bangladesh in whom a high prevalence of ETEC was found, although these infections peaked during the dry, warm months.14 Similar results have been reported for ETEC infections in children from Egypt.15 In contrast, in another study in children and adults in Tanzania, a seasonal difference in the prevalence of ETEC was not observed.16
Many reports have demonstrated the association of EAEC with diarrhea in children in developing countries.13,17 Similarly, our results show a high proportion of EAEC found in children with diarrhea in Tanzania, especially in the dry season.
Only one isolate of EIEC and another of VTEC were recovered during the study. The low levels of these pathogens is consistent with previous reports that showed the low prevalence of EIEC as a cause of diarrhea in children less than five years old.18 It has been reported that VTEC mainly affects developed countries.19
Our results obtained show a low prevalence of Campylobacter spp. Although a higher prevalence (2.9%) of Campylobacter was found during the dry season than in the rainy season, this difference was not significant. A high prevalence of Campylobacter has been reported during the wet season in Zaire,20 although other investigators did not find seasonal differences.16
Shigella spp. were isolated at a higher frequency during the dry season. This result is consistent with a previous report that showed that shigellosis was more prevalent during dry months.6 Although, it should be mentioned that the results obtained in our study might be biased by the superimposition of a Shigella flexneri outbreak during the dry season,21 this outbreak might also explain the differences found among dysentery cases in both seasons.
Rotavirus has been reported as the main virus associated with diarrhea in young African children.22–24 The mortality associated with this pathogen in sub-Saharan areas of Africa has been estimated to be approximately 145,000 deaths/year. In our study, a high frequency of rotavirus was detected during the dry season. This is consistent with previous observations of a peak in the incidence of rotavirus during the dry season in children with diarrhea from different areas of Africa.12,24,25
Giardia lamblia was another microorganism in which a significant difference in its frequency was found between the dry and the rainy seasons. A seasonal difference in the prevalence of G. lamblia has also been reported in a study in children from Jordan.4
In summary, the present study shows that diarrheogenic E. coli are the predominant enteropathogen causing diarrhea in children less than five years old in Ifakara, Tanzania in both the dry and the rainy seasons. Moreover, ETEC, Shigella spp., and rotavirus were more prevalent in the dry season, whereas EAEC and G. lamblia were more prevalent in the rainy season.
Received October 12, 2003. Accepted for publication December 26, 2003.
Acknowledgments: The support of John J. Aponte is greatly appreciated.
Financial support: This work was supported in part by the Spanish Agency of International Cooperation (AECI-1042) and the Ministerio de Educación y Cultura, Spain (fellowship to Martha Vargas).
Authors’ addresses: Martha Vargas, Climent Casals, and Jordi Vila. Departament of Microbiology, Institut Clinic Infeccions Immunologia, Institut d’Investigacions Biomediques August Pí i Sunyer, Hospital Clínic, Villarroel 170, 08036 Barcelona. Spain. Joaquim Gascón and Joaquim Ruiz, Tropical Medicine Unit, Unitat Avaluació Suport I Prevenció, Institut d’Investigacions Biomediques August Pí i Sunyer, C/Roselló 132, 2°-2ª, 08036 Barcelona, Spain. David Schellemberg. Epidemiology and Bioestadistics Section, Unitat Avaluació Suport I Prevenció, Institut d’Investigacions Biomediques August Pí i Sunyer, C/Roselló 132, 2°-2ª, 08036 Barcelona, Spain and Ifakara Health Research and Development Centre, National Institute for Medical Research, Ifakara, Tanzania. Honorati Urassa and Eliseus Kahigwa. Ifakara Health Research and Development Centre, National Institute for Medical Research, Ifakara, Tanzania.
Reprint requests: Jordi Vila, Departament of Microbiology, ICII, Institut d’Investigacions Biomediques August Pí i Sunyer, Hospital Clínic, Villarroel 170, 08036 Barcelona, Spain. Telephone: 34-93-227-5522, Fax: 34-93-227-9372, E-mail: vila{at}medicina.ub.es.
|
REFERENCES |
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  I. Mandomando, D. Jaintilal, M. J. Pons, X. Valles, M. Espasa, L. Mensa, B. Sigauque, S. Sanz, J. Sacarlal, E. Macete, et al. Antimicrobial Susceptibility and Mechanisms of Resistance in Shigella and Salmonella Isolates from Children under Five Years of Age with Diarrhea in Rural Mozambique Antimicrob. Agents Chemother., June 1, 2009; 53(6): 2450 - 2454. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Mendez-Arancibia, M. Vargas, S. Soto, J. Ruiz, E. Kahigwa, D. Schellenberg, H. Urassa, J. Gascon, and J. Vila Prevalence of Different Virulence Factors and Biofilm Production in Enteroaggregative Escherichia coli Isolates Causing Diarrhea in Children in Ifakara (Tanzania) Am J Trop Med Hyg, June 1, 2008; 78(6): 985 - 989. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. M. MANDOMANDO, E. V. MACETE, J. RUIZ, S. SANZ, F. ABACASSAMO, X. VALLES, J. SACARLAL, M. M. NAVIA, J. VILA, P. L. ALONSO, et al. ETIOLOGY OF DIARRHEA IN CHILDREN YOUNGER THAN 5 YEARS OF AGE ADMITTED IN A RURAL HOSPITAL OF SOUTHERN MOZAMBIQUE Am J Trop Med Hyg, March 1, 2007; 76(3): 522 - 527. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
