Enteropathogen carriage by healthy individuals living in an area with poor sanitation

Coproantibodies to the enteropathogenic Escherichia coli vaccine candidates BfpA and EspB in breastfed and artificially fed children

A diagnostic test was developed to discriminate active from past enteropathogenic Escherichia coli (EPEC) infection, which uses the affinity-purified recombinant proteins BfpA (bundle-forming pilus (BFP) structural repeating subunit A) and EspB (pore-forming secreted protein B) as reliable markers of virulence to detect antigen-specific coproantibodies by immunoblot analysis, and verification of active typical EPEC infection by gene-specific (bfpA and espB) PCR amplification using DNA extracted directly from specimens and/or culture-enriched preparations. To begin addressing the potential protective role of anti-EPEC antibodies at early age, the prevalence of IgA coproantibodies to these antigens was determined in either breastfed or artificially fed children <2 years of age hospitalized for watery diarrhea.

Asymptomatic infections by diarrheagenic Escherichia coli in children from Misiones, Argentina, during the first twenty months of their lives

Diarrheagenics Escherichia coli are the major agents involved in diarrheal disease in developing countries. The aim of this study was to evaluate the time of appearance of the first asymptomatic infection by the different categories of diarrheagenic E. coli in 44 children since their birth and during the first 20 months of their lives. In all of the children studied, we detected at least one category of diarrheagenic E. coli through the 20 months of the study. 510 diarrheagenic E. coli (33.5%) were obtained from the 1,524 samples collected from the 44 children during the time of the study (31.4% EAggEC, 28.8% EPEC, 27.1% DAEC, and 12.7% ETEC). Neither EHEC nor EIEC were identified. The median age for diarrheagenic E. coli colonization was 7.5 months. The mean weaning period was 12.8 months and the mean age for introduction of mixed feeding (breast fed supplemented) was 3.8 months. A significantly lower incidence of diarrheal disease and asymptomatic infections was recorded among the exclusively breast-fed rather than in the supplemented and non breast-fed infants. For ETEC, EPEC and EAggEC the introduction of weaning foods and complete termination of breast-feeding were associated with an increase of asymptomatic infections.

Prospective study of enteropathogens in two communities of Misiones, Argentina

Children under five years of age, from two communities of different socio-economic strata (97 from Zaiman and 55 from Las Dolores) were examined epidemiologically during 2 years, by means of quarterly visits of the working team, who carried out the collection of faecal samples. During the study, one or more enteropathogens were identified in 73.9% of samples in children from Zaiman and in 58.3% of the samples from Las Dolores, being associated to diarrhoea in 70.5% and to asymptomatic infections in 65.7%. The number of diarrheic episodes was higher in Zaiman (15.45%) than in Las Dolores (12.35%), being more frequent in the spring-summer seasons. In Zaiman, the bacterial enteropathogen proportion was relevantly higher (p < 0.005) in children with diarrhoea, whereas the presence of parasites was more frequent in asymptomatic children (p < 0.01). Rotavirus had an even distribution within diarrheic and asymptomatic children. In Las Dolores, no relevant differences were found in the detection of enteroparasites between diarrheic and asymptomatic children. Mixed infections were detected; enterotoxigenic Escherichia coli (ETEC)-rotavirus and ETEC-parasites being the most frequent ones. ETEC was involved in 85% of these infections. These data, together with the high enteropathogen carriage, suggest an elevated level of environmental contamination. The latter plays an important role in diarrheic diseases, and added to the most extreme poverty, it affects children's lives.

Hygiene habits and carriers in families with a child who has had typhoid fever

The relationship between asymptomatic shedding of bacterial enteropathogens and the hygiene habits of families who have had a child with typhoid fever (TF) are investigated. The sample was made up of 80 families: 40 families in which one child had had TF (Group A) and 40 in which no children or either of the parents had had a history of TF (Group B). In each group 20 families belonged to a low socioeconomic status (SES) and 20 to a high SES. A structured interview was used to evaluate the SES and the hygiene habits of the child; observations were made to measure the hygiene habits of the family (toilet, kitchen and food preparation) and bacteriological studies (fecal samples and hand markers). Results show that carriers were more frequent in Group A than in Group B. The bacterial species found were significantly more numerous in Group A than in Group B (fecal samples: E. coli, the classic serotypes, Shigella ssp, and hand markers: E. coli). Families of Group A had higher carriage rates than those of Group B. Finally there exists a significantly higher association between inadequate hygiene habits and carrier families. These results show the need to teach specific habits of proper hygiene to the entire population, because the fact of belonging to the high SES does not in itself preclude inadequate hygiene habits.

Enteropathogenicity of Aeromonas species isolated from infants: a cohort study

The significance of Aeromonas spp. as potential enteric pathogens was evaluated in a cohort of 187 infants aged 3-18 months during a 16-week summer period. Aeromonas spp. were isolated from 14 of the 196 (7.1%) diarrhoeal episodes detected and from eight (5.2%) of 153 samples from paired asymptomatic infants. Carriage of bacterial enteropathogens excluding Aeromonas spp. was detected in a high proportion (23%) of the asymptomatic children. Almost all of the seven isolates of Aeromonas sobria were enterotoxigenic, invasive and beta-haemolytic. In contrast, none of the seven Aeromonas caviae strains had these virulence-associated characteristics. The only isolate of Aeromonas hydrophila produced cytotoxic enterotoxin and was invasive. Plasmid analysis of selected strains did not correlate with these two properties or with antibiotic resistance. Nevertheless, the latter was found in an important proportion of the isolates. The diarrhoeal episodes, in which Aeromonas spp. were detected, lasted significantly longer, i.e. 17.2 days when the strains were invasive and/or toxigenic as compared with 4.3 days (P less than 0.001) in patients harbouring strains lacking both traits. These results reinforce the need to characterise virulence determinants before assigning any pathogenic role to Aeromonas spp. isolated from faecal specimens. Our findings also suggest the need for adequate antibiotic treatment in patients with confirmed Aeromonas spp. having enterotoxigenic and/or invasive properties.

Prevalence of cryptosporidiosis in Dammam and Alkhobar, Saudi Arabia

This report presents results from a 6-month study over the period 16 November 1986 to 15 May 1987 which was designed to investigate the prevalence of cryptosporidiosis in Dammam and Alkhobar, Saudi Arabia. A total of 209 stool specimens from children and 112 from adults with diarrhoea were examined. Only two (1%) of the children, both aged 2 years, were positive for Cryptosporidium spp. Giardia lamblia was found in 13 (4%) cases and was found to be the most common protozoan parasite, whereas Salmonella spp. was seen in 19 (6%) cases. Stool specimens were examined for rotavirus from children under 2 years of age; 31 (41%) of the specimens were positive.

High prevalence of campylobacter excretors among Liberian children related to environmental conditions

Campylobacter was the bacterial pathogen most prevalent in 859 children, aged 6-59 months, examined in a house-to-house diarrhoea survey in two Liberian communities. 44.9% of the children from an urban slum and 28.4% from a rural area were excretors. Since the prevalence of diarrhoea was very high and consequently many convalescent carriers were found, it was not possible to evaluate the pathogenic role of campylobacter. The excretor rate increased with age and was significantly correlated to the use of supplementary feeding, inversely correlated to the quality of the water supply, and also associated with helminthic infestation. Results from re-examination of 172 children suggested a high intensity of transmission. The findings all indicate the existence of a heavy environmental contamination with campylobacter, probably of both human and animal faecal origin.

Acute diarrhoea and asymptomatic infection in Chilean preschoolers of low and high socio-economic strata

Preschoolers who belonged to the high (Group I, n = 112) or the low (Group II, n = 90) socio-economic stratum were followed prospectively for six months. Mean monthly incidence of diarrhoea was 3 and 7 episodes per 100 children for Group I and Group II respectively (p less than 0.001). Episodes were shorter and affected a smaller proportion of children in Group I (p less than 0.002 and p less than 0.05), respectively). Bacterial enteropathogens were recovered in 12.6% and 13.5% of the episodes in Group I and Group II and parasites in 15.4% and 62.8%, respectively. Rotavirus was detected once in each group. Asymptomatic carrier rates for enteropathogenic bacteria were 12.0% in Group I and 7.2% in Group II. The corresponding figures for parasites were 28.2% and 62.8% (p less than 0.001). Nutritional status was normal in all children. These results suggest that socio-economic stratum plays an important role in the characteristics of diarrhoeal illness in the groups which conform the population of the less developed countries. Acute diarrhoea is less frequent in preschoolers living in Santiago than in other developing areas. Rates of asymptomatic infection are high.

Cryptosporidium spp., a frequent cause of diarrhea in Liberian children

This report presents results from a sample survey designed to investigate the possible role of Cryptosporidium spp. in childhood diarrhea in a developing country, Liberia, West Africa. During the four months of January to April 1983, a house-to-house study was carried out in two geographically and socially different communities--an urban slum and three rural villages. Stool samples from 374 children, aged 6 to 59 months, were tested for Cryptosporidium spp. Among the children with diarrhea 8.4% were Cryptosporidium spp. positive compared with a prevalence rate of 5.9% in asymptomatic children. Of the children living in a household with a Cryptosporidium spp.-positive index child, 8.6% had a positive stool sample. Of all children attending a clinic because of diarrhea, 14.6% were Cryptosporidium spp. positive. Cryptosporidiosis was more frequent in younger children; 24 of the total of 29 positive cases (83%) were below 2.5 years old. Actual or previous bottle feeding (formula) was a risk factor, particularly in children below 18 months old. Of the bottle-fed children, 28% were Cryptosporidium spp. positive versus 9.1% of children never bottle fed. Crowding is another possible risk factor. The prevalence of cryptosporidiosis was 13.5% in big urban households with more than 10 children, whereas the prevalence in the small urban households was 6.1%. Ethnic and religious differences were particularly evident in the rural area. No Muslim households had cryptosporidiosis, whereas the prevalence in non-Muslim tribes was 9%. The general belief that cryptosporidiosis is primarily a zoonosis is questioned in this study, partly because many carriers and asymptomatic household contacts were found.

Acute diarrhoeal disease in children under 7 years of age in a peri-urban slum of Santiago, Chile

A group of 168 families who lived in a peri-urban slum in Santiago were surveyed for 9 months. All of them had a child under 7 years of age. Medical activities and data collection were carried out at a Field Station and by means of twice-weekly visits to each home, at which time cases of diarrhoea were recorded and investigated. Faecal samples for bacteriological, parasitological and rotavirus studies were obtained during each episode. The characteristics of clinical course, hygienic practices in the family, and monthly anthropometric measurements of infants and toddlers were also recorded. The mean monthly incidence of diarrhoea was 7.1 episodes per 100 children. Of the episodes, 44.2% were associated with pathogenic bacteria, 14.4% with rotavirus, 38.4% with parasites and in 27.9% no enteropathogens were identified. It was found that adequate hygienic habits were not associated with a decreased risk of developing diarrhoea and that about 60% of children did not have diarrhoea throughout the study period. The nutritional status was adequate in most cases: weight-for-age was below the 5th percentile in 11.5% of subjects and the height-for-age was normal in all. No moderate or severe cases of malnutrition were detected.