Incidence of diarrhea in children living in urban slums in Salvador, Brazil.

Diarrhea remains a major health issue in developing countries, with high morbidity and mortality rates. Determining the incidence of acute diarrhea in children and its associated factors is crucial to the planning of preventive approaches. The objective of this study was to determine the incidence of diarrhea and to assess some relevant associated factors to it in children younger than 40 months living in two slums of Salvador, Brazil. This is the first prospective cohort, community-based study that was performed in two periurban slums of Salvador, Brazil. Eighty-four children younger than 40 months were randomly selected and visited every other day for one year. The chi-square test was used to evaluate the occurrence of diarrhea and its associated factors. During the surveillance period, 232 diarrhea episodes were identified, resulting in an incidence rate of 2.8 episodes/child/year. In average (mean value of 84 children),each child suffered 11.1 days of diarrhea per year, yielding an average duration of 3.9 days per episode. The highest incidence rates were found among children under one year old. Early weaning, male sex, malnutrition, having a mother younger than 25 years or who considered her child malnourished, missed immunizations and previous pneumonia were associated factors for suffering diarrheal episodes. The rates of incidence and duration of diarrhea that we found are in accordance to those reported by others. Additionally, our results reinforce the importance of environmental and health-related associated factors to the onset of diarrhea.     

Astrovirus diarrhea in Egyptian children

This study describes the epidemiology of astrovirus diarrhea among a population-based cohort of 397 children aged <3 years residing in rural Egypt from 1995 to 1998. The age-specific incidence rates of astrovirus diarrheal episodes per person-year were 0.38 for infants aged <6 months, 0.40 for those aged 6-11 months, 0.16 for those aged 12-23 months, and 0.05 for those aged 24-35 months. The overall incidence rate of astrovirus diarrhea was the same as that of rotavirus diarrhea, 0.19 episodes per person-year. Astrovirus infection was pathogenic and associated with severe dehydration in 17% of the cases. The most frequent serotype was HAstV-1, and, in order of decreasing frequency, HAstV-5, HAstV-8 and HAstV-3, HAstV-6, HAstV-4, and HAstV-2. In determining whether astrovirus diarrhea was associated with a reduced incidence of subsequent disease, there was evidence to suggest HAstV-1 homotypic immunity but not heterotypic immunity. Because we observed 38% of the incidence of astrovirus diarrhea to occur in infants aged <6 months, a candidate astrovirus vaccine would have to confer immunity very early in life.     

Diarrhoeal diseases amongst children under five. A study in rural Alwar.

A house to house survey was done in three villages of district Alwar covering 875 children under five years age. Two week incidence of diarrhoea morbidity was 2.27 episodes/child/year taking into consideration the seasonal correction factor. The incidence decreased with increase of age. Incidence was found significantly more in children of illiterate mother (p < 0.05). Children of poor socio-economic conditions as determined by occupational status (labourers) suffered significantly more often from diarrhoea as compared to children of higher socio-economic status (agriculturist and others). Fifty per cent episodes of diarrhoea were treated with antibiotics, and only one child was given ORS. It is a matter of concern. About 3.7 per cent mothers washed their hands before preparing meals while, 1.6 per cent washed their hands after toilet. Only 2 per cent mothers had the knowledge of preparing the home made salt sugar solution. An intensive health education campaign is therefore, necessary for health professionals as well as mothers.     

Community Diarrhea Incidence Before and After Rotavirus Vaccine Introduction in Nicaragua

We estimated the incidence of watery diarrhea in the community before and after introduction of the pentavalent rotavirus vaccine in León, Nicaragua. A random sample of households was selected before and after rotavirus vaccine introduction. All children < 5 years of age in selected households were eligible for inclusion. Children were followed every 2 weeks for watery diarrhea episodes. The incidence rate was estimated as numbers of episodes per 100 child-years of exposure time. A mixed effects Poisson regression model was fit to compare incidence rates in the pre-vaccine and vaccine periods. The pre-vaccine cohort (N = 726) experienced 36 episodes per 100 child-years, and the vaccine cohort (N = 826) experienced 25 episodes per 100 child-years. The adjusted incidence rate ratio was 0.60 (95% confidence interval [CI] 0.40, 0.91) during the vaccine period versus the pre-vaccine period, indicating a lower incidence of watery diarrhea in the community during the vaccine period.     

The incidence of diarrheal disease in a defined population of rural Egypt

A prospective study of diarrheal illness was conducted for 2 years in 309 families who were part of an epidemiologic research center population in rural Egypt. The rates of illness peaked in the first year of life with between 5 and 6 episodes per person year at risk. Although no seasonal variation in reported diarrhea was demonstrated for the total population, age-specific differences in seasonal occurrence were noted. The incidence did not consistently vary by village size, nor did rates vary by sex.     

Population-based estimates of the cumulative risk of hospitalization potentially associated with rotavirus diarrhea among children living in two cities in Akita Prefecture, Japan

A 4-year retrospective population-based survey was conducted in two cities in Akita Prefecture, Japan, to estimate the incidence rate and the cumulative risk of hospitalization potentially associated with rotavirus diarrhea. At monthly occasions of the 3-year-old checkup, we asked each parent if his or her child had ever been hospitalized because of rotavirus diarrhea. Based on 3-year follow-up of the four consecutive birth cohorts (1996-1999), we calculated the incidence rate and the cumulative risk of rotavirus-associated hospitalizations by the age of 3 years. The incidence rates of rotavirus-associated hospitalization in 1-year-old children in Akita city and Honjo city were 9.7 and 16 hospitalizations per 1,000 children per year, respectively, whereas 1.9% of children in Akita city and 3.3% of children in Honjo city were hospitalized by their third birthday because of rotavirus-associated diarrhea. The burden of rotavirus diarrhea in this region of Japan, and probably across the nation, appears substantially large.     

Incidence of diarrhea caused by rotavirus infections in rural Zhengding, China: prospective, population-based surveillance

Rotavirus is the pathogen most commonly associated with severe gastroenteritis in young children in the People's Republic of China, yet there are few population-based data on the incidence of rotavirus infection. The present study investigated the burden of rotavirus diarrhea and rotavirus infections in rural China, according to age. Population-based surveillance was used to study the incidence of rotavirus infection among children <5 years of age in 4 townships of Zhengding County, Hebei Province, China. The total population in the catchment area in 2002 was 75,630 individuals, including 2997 children aged <5 years. Stool samples were obtained and were tested for rotavirus antigen by use of an enzyme-linked immunosorbent assay. During 2002, a total of 2010 cases of diarrhea were detected among children <5 years of age. The incidence of treated cases of diarrhea was 671 cases/1000 children/year for children <5 years of age, and it was highest for children <12 months of age (1467 cases/1000 children/year). The estimated incidence of rotavirus infection was 151 cases/1000 children/year for children <5 years of age. The highest incidence of rotavirus infection was among children aged 1-2 years (340 cases/1000 children/year). Widespread immunization of children against rotavirus before 6 months of age should be considered for the control of rotavirus diarrhea.     

Impact of fly control on childhood diarrhoea in Pakistan: community-randomised trial

Since circumstantial evidence suggests that flies are vectors of diarrheal diseases, a randomized study of the effect of insecticide spraying upon the incidence of diarrhea was conducted near the town of Peshawar, North West Frontier Province, Pakistan. 6 study villages were randomly assigned to 2 groups, with flies controlled through the twice weekly application of ultra low volume space spraying with insecticide in group A in 1995 and in group B in 1996. The insecticide used was Aqua K-Othrine, a water-based formulation of deltamethrin, applied at a dose of 0.5-1.0 g of active ingredient per hectare by Porta-Pak sprayers. In 1997, the effectiveness of baited fly traps was tested in group A villages. The incidence of diarrhea episodes was monitored in children under age 5 years through mothers' reports during weekly visits by a health worker, and fly density was monitored using sticky fly-papers hung in sentinel compounds. During the fly seasons of March-June in 1995 and 1996, the application of insecticide almost eliminated the fly population in the treated villages. The incidence of diarrhea was lower in the sprayed villages than in the unsprayed villages in both 1995 and 1996, for an overall 23% reduction in incidence. At times other than the fly season, no evidence was observed of a difference in diarrhea morbidity between sprayed and unsprayed villages. Fly density data for 1997 found the baited traps to be ineffective.     

Incidence of pneumonia,bacteremia, and invasive pneumococcal disease in Pakistani children

Objective To determine the incidence of pneumonia, bacteremia, and invasive pneumococcal disease (IPD) in Pakistani children <5 years old. Methods Household surveillance from 1st February 2007 to 12th May 2008 was conducted in two low‐income, coastal communities of Karachi. Community health workers referred each sick child <5 years old to the local clinic. Blood culture was obtained whenever possible from children meeting inclusion criteria. Results Overall, 5570 children contributed 3949 observation years. There were 1039 clinical cases of pneumonia, of which 54 were severe pneumonia and four cases of very severe disease according to WHO criteria. The overall pneumonia incidence was 0.26 (95% CI: 0.25–0.28) episodes per child‐year. A pathogen was isolated from the blood of 29 (2.8%) pneumonia cases. Bacteremia incidence was 912 (95% CI: 648–1248) episodes per 100 000 child‐years with a case fatality rate of 8%. The detected IPD incidence was 25 (95% CI: 1–125) episodes per 100 000 child‐years. The under‐five mortality rate was 55 per 1000 live births, with pneumonia causing 12 (22%) deaths among children <5 years old. Conclusion Clinical pneumonia is common in Pakistani children, with one in four deaths attributable to the disease. Bacteremia occurs at a high rate but surveillance for pneumococcus underestimates the burden of IPD.     

Persistent high risk of diarrhea among foreigners in Nepal during the first 2 years of residence.

Although numerous studies have shown that diarrhea is the most common illness occurring during the first few weeks of travel, systematic studies of the incidence of diarrhea during long-term residence in developing countries have not been performed. We conducted a cohort study of the incidence and etiology of diarrhea among 77 expatriate adults who had lived in Nepal for <2 years. Persons were followed prospectively for up to 1 year (mean, 9 months). The incidence of diarrhea during the surveillance period was 3.3 episodes of diarrhea per person per year, or 0.27 episodes per person per month. The annual attack rate of specific pathogens was 42% for enterotoxigenic Escherichia coli, 32% for Cyclospora species, 16% for Giardia lamblia, 16% for Shigella species, 10% for Campylobacter species, > or =10% for rotavirus, and 6% for Entamoeba histolytica. This study suggests that adult persons from developed countries who move to developing countries such as Nepal remain at high risk for diarrhea during their first 2 years of residence.     

Changes over time in the epidemiology of diarrhea and malnutrition among children in an urban Brazilian shantytown, 1989 to 1996.

BACKGROUND: Endemic diarrhea and its associated malnutrition remain leading causes of childhood morbidity and mortality in developing countries. This study was undertaken to describe changes in the incidence of diarrhea and prevalence of malnutrition among children in an urban Brazilian shantytown from 1989 to 1996. A secondary purpose was to examine associations between malnutrition and increased incidence and duration of diarrhea. METHODS: From August 1989 through December 1996 a dynamic birth cohort of 315 children was followed for surveillance of diarrhea and nutrition. Study homes were visited twice or thrice weekly to assess the occurrence of diarrhea. Length and weight of the subjects were measured quarterly. Poisson regression was used to test for associations between prior nutritional status and subsequent diarrhea during a quarter. Multiple regression was used to test for an association between nutritional status and episode duration. RESULTS: Declines in both age-adjusted attack rates (6.0 episodes/child-year in study year 3 [1991] to 2.5 episodes per child-year in study year 8 [1996] and days of diarrhea per child-year (30.8 days/child-year in year 3 to 8.5 days/child-year in year 8) were correlated with yearly improvements in mean nutritional status (R2= 0.84, P < 0.05, for mean length-for-age with mean number of episodes/child-year [corrected]. Both length- and weight-for-age were significant predictors of diarrhea incidence, including persistent episodes (> or =14 d), but not duration. CONCLUSIONS: These results demonstrate marked changes over time in the diarrhea burden and nutritional status of children in this population and provide further evidence of a significant association between malnutrition and increased incidence of diarrhea.     

Malaria incidence in relation to rice cultivation in the irrigated Sahel of Mali

Seven repeated cross-sectional parasitological surveys, collecting a total of 13,912 blood samples, were carried out from September 1995 to February 1998 in three irrigated rice growing villages and three villages without irrigated agriculture in the area surrounding Niono, Mali. Parasite prevalence varied according to season and agricultural zone, but showed similar patterns for villages within the same zone. Overall, malaria prevalence was 47% in the villages without irrigated agriculture and 34% in the irrigated rice growing villages. In a village in the irrigated zone, and a village in the non-irrigated zone, 1067 and 608 children up to the age of 14 years, respectively, were followed in a passive malariological study for the period of 13 months. Fevers were attributed to malaria using a statistical method, taking into account the parasitaemia in afebrile controls from the cross-sectional surveys. The incidence of malaria fevers differed markedly between the two zones and over time. In the village in the irrigated zone, the incidence of malaria fevers was fairly constant over the year at 0.7 per 1000 children per day. In the village without irrigated agriculture, incidence was low during the dry season (at 0.6 per 1000 children per day), whereas it was high during the rainy season (at 3.2 per 1000 children per day). These results correspond well to the malaria transmission observed in a concurrent entomological survey. Rice cultivation in the semi-arid sub-Saharan environment altered the transmission pattern from seasonal to perennial, but reduced annual incidence more than two-fold.     

The detection of enteropathogens in acute diarrhea in a family cohort population in rural Egypt

In 8 villages of rural northeastern Egypt, a 2-year study of the etiologic agents associated with episodes of diarrhea was carried out. Stool specimens (3,243) from 3,513 episodes of diarrhea were processed for enteropathogens. The most commonly identified agents in the group with diarrhea were Giardia lamblia (44%), heat stable enterotoxin (ST)-producing enterotoxigenic Escherichia coli (ETEC) (15%), heat labile toxin (LT)-producing ETEC (12%), enteropathogenic E. coli (EPEC) (4%), rotavirus (3%), Shigella (2%) and Salmonella (1%). Isolation rates were increased in cases compared to controls for all agents except G. lamblia and EPEC strains. Rotavirus, Salmonella and ST-producing ETEC were more frequently isolated during cooler months and Shigella and LT-ETEC occurred more commonly in warmer months. Campylobacter, EPEC, Giardia and E. histolytica did not show a discernable seasonal pattern. Rotavirus was primarily associated with diarrhea in infants only. Forty-four percent of children experienced at least 1 bout of rotavirus diarrhea by the age of 3 years. Vomiting was reported in 65% of cases of rotavirus infection. Dehydration was reported in greater than 40% of those with rotavirus-, Salmonella-, Campylobacter-, LT-ETEC- and EPEC-associated illness and in those without an identifiable agent. While rotavirus was implicated in 3% of cases overall, when vomiting or vomiting plus dehydration occurred, rotavirus was identified with a rate of 10% and 12%, respectively. Dysentery was common only in Shigella cases, occurring in 24%. A decrease in occurrence of rotavirus, Campylobacter and possibly EPEC illness was seen in the infants less than 6 months of age who were breast-fed when compared to those who were not.     

Epidemiologic and clinical characteristics of acute diarrhea with emphasis on Entamoeba histolytica infections in preschool children in an urban slum of Dhaka, Bangladesh

The epidemiology, clinical features, nutritional status, and causative agents of diarrhea were studied in 289 Bangladeshi children (147 boys and 142 girls) 2-5 years old. The use of improved diagnostic tests for amebiasis enabled for the first time analysis of the contribution of Entamoeba histolytica to total diarrheal illness in this community setting. The average incidence rate of diarrhea was 1.8/child-year, and the average number of diarrheal days was 3.7 days/child-year over an average observation period of 2.8 years/child. Seventy-five percent of the diarrheal episodes were < or = 2 days in duration. Persistent diarrhea was relatively uncommon (0.2% of the children) and chronic diarrhea was observed in only one episode. Compared with malnourished and/or stunted children, better-nourished children experienced significantly fewer diarrheal episodes. The diarrheal incidence rate for children with blood group A was significantly less that that of the children with blood groups O and AB. The most frequent bacterial enteropathogens isolated from diarrheal stool specimens were enterotoxigenic Escherichia coli (9%) and Aeromonas species (9%), followed by Plesimonas shigelloides (4%) and Shigella flexneri (3.8%). Rotavirus was the most common viral agent isolated from diarrheal stool samples (5%). Giardia lamblia, Cryptosporidium parvum, and E. histolytica were identified in 11%, 8.4%, and 8%, respectively, of the diarrheal stool specimens. Dysentery was observed in 7.7% of all diarrheal episodes. The most common pathogens isolated from dysenteric stool were S. flexneri (11.6%), Aeromonas sp. (10%), E. histolytica (8.7%), Campylobacter jejunii (5.8%), P. shigelloides (4.3%), and A. caviae (4.3%). The overall incidence rate of E. histolytica-associated diarrhea was 0.08/child-year. Visible blood and hemoccult test-detected blood loss was found in 7% and 25%, respectively, of cases of E. histolytica-associated diarrhea. Children who had recovered from a diarrheal episode with E. histolytica, but not E. dispar, had half the chance of developing subsequent E. histolytica-associated diarrhea, consistent with the development of species-specific acquired immunity. In conclusion, the use of modern diagnostic tests demonstrated that E. histolytica contributed to overall morbidity from diarrheal illness. Understanding the etiology, frequency, and consequences of acute diarrhea in children from a developing country should aid in the design of interventions to improve child health.     

Season of birth is not associated with delayed childhood mortality in Upper River Division, The Gambia

There is evidence that season of birth may predict adult mortality from infectious diseases in rural Gambia. Using data collected over a five-year period from the rural, eastern region of the Gambia, we examined whether the season of birth influences mortality in childhood. 26 894 births and 3776 deaths among children under the age of five years were recorded in this region during the period 1989-1993. The estimated 1-4 year population was 95 355. In children aged 1-4 years, the mortality rate per 1000 per year was 16.1 (95% CI 14.9, 17.2) for those born in the 'harvest' season (January to June), which was not significantly different from the rate of 17.9 (95% CI 16.7, 19.0) recorded for those born in the 'hungry' season (July to December) (age-stratified Mantel-Haenszel mortality ratio 0. 91, 95% CI 0.83, 1.01; p = 0.08). Nearly all deaths of 1-4 year olds were attributed to infectious diseases, with malaria accounting for over 40%. None of the cause-specific child mortality rates differed significantly according to the season of birth. These data suggest that beyond infancy, when it is easier to separate the effect of season on cause of death from that of the season of birth, there is no marked difference in the rate of death between Gambian children born in the harvest season and those born in the hungry season.     

Diarrheal morbidity and mortality in children in the Central African Republic

Diarrheal morbidity and mortality in children less than 5 years old were studied in Bangui, Central African Republic, by a cluster survey. We found a high prevalence of diarrheal disease with an estimated annual incidence of 7 episodes of diarrhea per child per year. The estimated annual mortality rate for children less than 5 years old was 28.6 per 1,000 and 85.8 per 1,000 for infants; 51.6% of deaths were reported to be associated with diarrhea. During the survey, stool specimens were collected from 133 children with current diarrhea and 117 control children to study the etiologic agents of diarrheal disease in the community. An enteric pathogen was identified in 58% of diarrheal children's stools and 48% of stools of well children. A statistically significant association between diarrhea and rotavirus was found, with it being isolated from 8 of 33 (24%) of stools of infants with diarrhea compared to 0 of 25 (0%) of control infants. Isolation rates for Campylobacter jejuni, Entamoeba histolytica, pathogenic Escherichia coli, and other bacterial enteropathogens did not differ significantly between children with diarrhea and control children.     

Epidemiology and strain characterization of rotavirus diarrhea in Malaysia.

OBJECTIVES: The objectives of the study were to describe the epidemiology and strain characterization of rotavirus (RV), to determine the proportion of hospitalizations for diarrhea attributable to RV among children under 5 years of age, and to estimate the disease burden of RV diarrhea in Malaysia. METHODS: All children 0-59 months of age admitted for acute gastroenteritis to Kuala Lumpur Hospital (KLH) or Hospital Umum Sarawak (HUS) were surveyed. The periods of surveillance were from February 1, 2001 to April 30, 2003 in KLH and April 1, 2001 to March 31, 2003 for HUS. RESULTS: The highest rate of RV-associated diarrhea was among children aged 6-17 months, accounting for 55% of RV-associated diarrhea. There was no seasonality observed in either hospital. P[8]G9 strains were predominant, accounting for 73% of all strains in both hospitals, 80% from KLH and 61% from HUS. There was no mortality. CONCLUSIONS: RV was responsible for 38% of hospitalizations for diarrhea. It was most common in the 6-17 months age group. There was no seasonality observed for RV-associated diarrhea. The most prevalent strain of RV was P[8]G9. The estimated incidence of RV-associated diarrhea was 27 per 10000 population under the age of 5 years per year.     

Enteropathogens associated with acute and persistent diarrhea in Bangladeshi children less than 5 years of age.

A longitudinal study of diarrhea was carried out from May 1988 to April 1989 by household surveillance of 705 children less than 5 years old in rural Bangladesh. Stool samples were examined for enteric pathogens at the beginning of each diarrheal episode. For persistent episodes, stool examination was repeated on days 15-17 of the illness. For each case of persistent diarrhea, stool samples from age-matched acute diarrheal and healthy controls were examined. Compared with healthy controls, cases of diarrhea were associated with Shigella species (P = .07) and rotavirus (P less than .05). Diffusely adherent Escherichia coli (P less than .05) and cryptosporidia (P = .07) were the only enteropathogens associated with persistent diarrhea in comparison with acute diarrhea. No more than 15% of children had the same class of pathogen identified from stool on both days 1-3 and days 15-17, indicating that persistent infection was uncommon. However, a different enteropathogen was frequently found on days 15-17, suggesting that sequential infection may be a cause of persistent diarrhea.     

Epidemiology of Shigella-associated diarrhea in rural Egyptian children

During the period from February 1995 to February 1998, the epidemiology of Shigella diarrhea was studied among children less than three years of age residing in Egypt's Nile Delta. Children were visited twice a week and a stool sample was collected from any of them with diarrhea. The incidence of Shigella-associated diarrhea was 0.2 episodes/child-year, with S. flexneri being the most common serogroup isolated (55% of Shigella episodes). Younger age and the warm months increased the risk of developing Shigella-associated diarrhea, while breastfeeding was protective. Children with Shigella were ill for a mean of four days and passed a mean of six stools per day. Common symptoms included fever (35%), vomiting (19%), and dehydration (16%). Dysentery, however, was unusual, occurring in only 11% of the cases. In conclusion, Shigella-associated diarrhea remains relatively common in Egyptian children and supports the need for additional control measures including vaccine development.     

Changes in the pattern of infant and childhood mortality in Upper River Division, The Gambia, from 1989 to 1993

A surveillance system was used to detect births and deaths in children in a large, rural, West African population from 1989 to 1993. Cause of death was investigated using post‐mortem questionnaires. Overall infant (age 0–11 months) and child (age 1–4 years) mortality rates of 80.1 and 18.8 per 1000 per year were recorded. These were reasonably consistent over the period of surveillance. The most frequent cause of death in infants was acute respiratory infection (ARI), whereas in children it was malaria: these two conditions accounted for 41% of the deaths in children under 5 years old. Other leading causes of death were acute gastroenteritis, malnutrition, and septicaemia. Deaths attributed to ARI decreased over the 5‐year period, but mortality rates from other causes were either unchanged or increased slightly. Mortality from all causes peaked in the rainy season and was slightly higher in villages which were part of a primary health care programme than in those which were not. There were also no differences between male and female mortality rates beyond one year of age. Despite the introduction of a number of health interventions, there has been no major change in the overall pattern of mortality in children in a rural area of The Gambia. Malaria and ARI remain the main causes of death.