Clinical and Serological Assessment of Children Exposed in Utero to Confirmed Maternal Rubella

As a result of the work of the Public Health Laboratory Service Working Party on Rubella (1970) it was possible to examine the children of 60 susceptible women who were in contact with rubella during their pregnancy and who subsequently showed serological evidence of the infection, despite immunoglobulin prophylaxis. When the children were assessed between 8 months and 4 years 8 months of age a blood sample was also taken and tested for rubella antibodies so that a retrospective diagnosis of congenital rubella infection could be made. Only 19% of children exposed to subclinical maternal rubella showed evidence of intrauterine infection compared with 53% of those born to mothers who had clinical rubella. One of the 26 children exposed to subclinical maternal infection had a rubella defect, compared with 9 of the 34 children exposed to clinical maternal rubella.     

Monocyte epigenetics and innate immunity to malaria: yet another level of complexity?

Children under the age of 5 years living in areas of moderate to high malaria transmission are highly susceptible to clinical malaria with fever that prompts treatment of blood stage infection with anti-malarial drugs. In contrast, older school age children frequently experience subclinical malaria, i.e. chronic Plasmodium falciparum parasitemia without fever or other clinical symptoms. The role of innate immune cells in regulating inflammation at a level that is sufficient to control the parasite biomass, while at the same time maintaining a disease-tolerant clinical phenotype, i.e., subclinical malaria, is not well understood. Recent studies suggest that host epigenetic mechanisms underlie the innate immune homeostasis associated with subclinical malaria. This Current Opinion article presents evidence supporting the notion that modifications of the host monocyte/macrophage epigenome regulate innate immune functions pertinent to subclinical malaria.     

Plasmodium falciparum malaria and sickle cell gene in the popular Republic of Congo. I. Relationship between parasitemia and sicke cell trait in Djoumouna (region of Brazzaville) (author's transl)

The relationship between sickle cell trait and falciparum malaria was studied in the village of Djoumouna, twenty kilometers south west of Brazzaville. Malaria is characterized by a stable high intensity of transmission on the average one infective mosquito bite by night and by child contrasting with a relatively low malarial infection rate. The prevalence of carriers of an S gene (AS) does not change with age: 22.2% for children under 5 years, 22.1% for childrern between 5 and 15 years, and 22.9% in adults. Malarial infection rates are 32% in homozygous AA children under five years and 38% in AS children, an insignificant difference. Our data for this region of the Congo fail to confirm the hypothesis that the AS genotype protects the carrier against Plasmodium falciparum infection.     

On the incidence of diarrhoea among young Indian children

Diarrhoea, claiming over three million young lives in the world every year, is the second biggest killer of children in developing countries. Using data for over 13,000 children in rural India, under the age of 3 years, this paper examines the relative effects of the different factors--inter alia the quality of the water supply, mother's literacy, housing conditions, and the level of development of the villages in which the children lived--contributing to diarrhoea. The paper highlights the importance of two factors: that children born to undernourished mothers may be more susceptible to infection than children whose mothers are well nourished, and that good hygienic practices within the home, such as washing hands with soap before feeding a child, can reduce the incidence of diarrhoea. The paper also quantifies the relative strength of the factors that determine whether mothers do so. The results emphasize the importance of mothers being literate, of household affluence and of institutional support (through the availability of trained midwives and mother and child centres in villages) in promoting domestic hygiene.     

Genitourinary schistosomiasis among pre-primary schoolchildren in a rural community within the Cross River Basin, Nigeria

In Africa, most schistosomiasis control programmes defined the age 5-19 years as the target population for nationwide control through the school systems, excluding the under fives. A study was therefore undertaken to determine the prevalence and intensity of genitourinary schistosomiasis in children aged 0-5 years (pre-primary) in Adim, a rural and endemic community within the Cross River Basin, Nigeria. Of the 126 children examined, 25 (19.8%) were infected with Schistosoma haematobium, with no significant difference (P > 0.05) in infection rates between boys (21.1%) and girls (18.2%). Both prevalence and intensity of infection increased significantly (P 0.05) between intensity in boys (6.2 eggs/10 ml urine) and girls (5.6 eggs/10 ml urine). A total of 32.5 and 27.8% of the children had haematuria and proteinuria, respectively; it was not gender specific (P > 0.05). Six species of snail were encountered, with Bulinus globosus being the most abundant and widespread. The results of this study have shown that pre-primary schoolchildren are a source of transmission of schistosomiasis in endemic communities and should be integrated into any control intervention.     

Exposure, infection, systemic cytokine levels and antibody responses in young children concurrently exposed to schistosomiasis and malaria

Despite the overlapping distribution of Schistosoma haematobium and Plasmodium falciparum infections, few studies have investigated early immune responses to both parasites in young children resident in areas co-endemic for the parasites. This study measures infection levels of both parasites and relates them to exposure and immune responses in young children. Levels of IgM, IgE, IgG4 directed against schistosome cercariae, egg and adult worm and IgM, IgG directed against P. falciparum schizonts and the merozoite surface proteins 1 and 2 together with the cytokines IFN-γ, IL-4, IL-5, IL-10 and TNF-α were measured by ELISA in 95 Zimbabwean children aged 1-5 years. Schistosome infection prevalence was 14·7% and that of Plasmodium infection was 0% in the children. 43. 4% of the children showed immunological evidence of exposure to schistosome parasites and 13% showed immunological evidence of exposure to Plasmodium parasites. Schistosome-specific responses, indicative of exposure to parasite antigens, were positively associated with cercariae-specific IgE responses, while Plasmodium-specific responses, indicative of exposure to parasite antigens, were negatively associated with responses associated with protective immunity against Plasmodium. There was no significant association between schistosome-specific and Plasmodium-specific responses. Systemic cytokine levels rose with age as well as with schistosome infection and exposure. Overall the results show that (1) significantly more children are exposed to schistosome and Plasmodium infection than those currently infected and; (2) the development of protective acquired immunity commences in early childhood, although its effects on infection levels and pathology may take many years to become apparent.     

Helicobacter pylori infection in childhood: risk factors and effect on growth.

OBJECTIVE--To investigate the current prevalence of Helicobacter pylori infection in childhood, the risk factors for infection, and the effect of infection on growth in preadolescent schoolchildren. DESIGN--Population based sample of 7 year old schoolchildren followed up at age 11; data on risk factors for infection collected at age 7; presence of infection at age 11 determined by measurement of salivary IgG against H pylori by a newly developed enzyme linked immunosorbent assay (ELISA). Height was measured at 7 and 11 years of age. SUBJECTS--554 schoolchildren from Edinburgh. RESULTS--62 (11%) children had H pylori infection. Independent risk factors for infection were single parent families (adjusted odds ratio = 2.5; 95% confidence interval 1.1 to 5.7), the 10% most crowded homes (3.1; 1.3 to 7.2), and schools serving predominantly rented housing estates (2.5; 1.0 to 6.5). School catchment area was more important than parental social class or housing tenure. Growth in height between 7 and 11 was diminished in infected children by a mean of 1.1 cm (0.3 to 2.0 cm) over four years. This growth reduction was largely confined to girls (1.6 cm over four years), among whom it correlated with salivary IgG (P = 0.015). CONCLUSION--Data from salivary assay to investigate the epidemiology of H pylori suggest that factors relating to the type of community in which the child lives may now be as important for acquisition of this infection as features of the family home. The greater reduction of growth among infected girls raises the possibility that H pylori infection may delay or diminish the pubertal growth spurt.     

Intestinal parasitoses among Wayampi Indians from French Guiana

Intestinal parasitism and its epidemiological characteristics were studied in an isolated Amerindian population from Upper Oyapock (French Guiana) that has retained its traditional social and cultural specificities. This population consisted of 138 Wayampi Indians, 68 adults and 70 children (below the age of 15 years), with a sex ratio (M/F) of 0.86, spread over the four villages of the community of Trois Sauts, corresponding to more than two thirds of the population recorded as inhabiting the sector in the last census (375 inhabitants). Fecal examination combined the direct examination of fresh feces with the quantitative techniques of Kato-Katz method, Baermann and MIF staining. Overall, 92% of the subjects were found to have intestinal parasites, 85% if only direct examination of fresh stools was taken into account. Fourteen species of human parasite were identified: seven protozoa and seven helminths. We observed in particular 1) a high frequency of hookworm infection due to Necator americanus. Over 50% of subjects were affected, with a range of 25% to 75% according to the village, but with only moderate parasite loads; 2) a high level of parasitism by E. histolytica/E. dispar (17%), Stongyloides stercoralis (16%) and Hymenolepis nana (18%); 3) a lower level of parasitism by Ascaris lumbricoides and very low levels (almost absent) of Trichiuris trichiura; 4) the absence of Schistosoma and fluke eggs. With the exception of H. nana, which was more frequent in children than in adults, there was no significant difference in the level of parasitism according to sex and age. Although the Wayampi of French Guiana are French citizens and consequently have quite high incomes and ready access to clinics and medicines, intestinal parasites are far from under control in this population. A lack of fecal hygiene and the habit of walking barefoot are widespread in the unchanging Amazonian environment and contribute to this phenomenon.     

Prevalence of Helicobacter pylori infection in Warao lineage communities of Delta Amacuro State, Venezuela

The purpose of this study was the evaluation of Helicobacter pylori infections in children and adults from two indigenous communities of Delta Amacuro State, Venezuela, that differ in hygienic conditions of the housing. The evaluation was performed in 98 children (mean age 7 +/- 3.37 years) and their mothers (33.96 +/- 13.77 years) from two communities of Warao lineage. Anti-H. pylori serum IgG and secretory anti-H. pylori IgA antibodies were determined, as well as total secretory IgA and H. pylori antigens in feces. Serological prevalence of H. pylori infection was 38% in children and 84% their in mothers. Children from the community that had the most deficient sanitary and hygienic conditions had significantly lower titers of specific IgG antibodies and total secretory IgA (P<0.0001) and a high percentage of them had H. pylori antigens in their feces (P<0.0001). The levels of specific IgA were similar in both groups. The results indicate that in these populations there is a high prevalence of H. pylori infection and that poor hygienic conditions can increase the risk of infection and damage to the gastrointestinal tract.     

Pediatric urolithiasis in Croatia

A retrospective review was performed of the records of 148 Croatian children with urolithiasis treated between 1989 and 2003. The study evaluated age, gender, family history, clinical symptoms, location of stone, laboratory findings, stone composition, mode of treatment and compared our results with data from higher and lower socio-economic countries. The mean age of our patients was 9.38 years (10 months to 18 years). Thirty-seven children (25%) were less than 5 years (group 1), 44 (29.7%) were between 5 and 10 years (group 2) and 67 (45.3%) were older than 10 years of age (group 3). There were 60 girls and 88 boys with overall male to female ratio of 1.47. Abdominal pain (83%) and haematuria (59.5%) were the main symptoms in the groups 2 and 3. Urinary tract infection was predominant symptom in the group 1 (62.1%). Calculi were located in the kidney in 90 children (60.8%), in the ureter in 39 (26.4%), in the bladder in 8 (5.4%). Urinary tract anomalies with or without infection were associate with a greater frequency of urolithiasis in the youngest age group and hypercalciuria was predominant cause in children over 5. Stone analysis was performed in 80 children. Predominant constituent of stones was calcium oxalate (48.7%), followed by struvite (25%), calcium phosphate (13.7%), cystine (10%) and uric acid (1.2%). Calcium oxalate stones were most common in all age groups. Struvite stones were most prevalent in the children younger than 5 years of age. Most patients (33.1%) underwent surgery for removal of their calculi. In 31.8% of children stones were passed spontaneously and the highest spontaneous passage rate was in the group 3 (37.3%). Stone composition, location and etiology in Croatian children are similar to those in developed Western countries.     

Epidemiology of soil-transmitted helminth infections in Semarang,Central Java,Indonesia

Soil-transmitted helminth (STH) infections are endemic in Indonesia. However, prevalence data for many parts of the country are incomplete. The aim of this study was to determine human STH prevalence and knowledge and practices relating to STH risk behaviour, to provide a current view of the status of STH infection in rural communities in Central Java. A cross-sectional survey of 16 villages was conducted in Semarang, Central Java in 2015. Demographic and household data together with information about knowledge and practices relating to STH and hygiene were elicited through face-to-face interviews. Stool samples were collected and examined using the flotation method. Children (aged 2–12 years) also had their haemoglobin (Hb) levels, height and weight data collected, and BMI estimated. Data were analysed using univariate logistic regression analysis. A total of 6,466 individuals with a mean age of 33.5 years (range: 2–93) from 2,195 households were interviewed. The overall prevalence of STH was 33.8% with Ascaris lumbricoides (roundworm) the predominant nematode identified (prevalence = 26.0%). Hookworm and Trichuris trichiura (whipworm) were found in 7.9% and 1.8% of participants, respectively. Females were at increased odds of infection with A. lumbricoides (adjusted OR 1.14, 95% CI [1.02–1.29], p = 0.02). Adults in age groups 51–60 and over 60 years had the highest odds of being infected with hookworm (adjusted OR 3.01, 95% CI [1.84–4.91], p<0.001 and adjusted OR 3.79, 95% CI [2.30–6.26], p<0.001, respectively) compared to 6–12 year olds. Farmers also had higher odds of being infected with hookworm (adjusted OR 2.36, 95% CI [1.17–4.76], p = 0.02) compared to other occupation categories. Poverty (OR 2.14, 95% CI [1.77–2.58], p<0.001), overcrowding (OR 1.35, 95% CI [1.27–1.44], p<0.001), goat ownership (OR 1.61, 95% CI [1.10–2.41], p = 0.02) and the presence of dry floor space in the home (OR 0.73, 95% CI [0.58–0.91], p = 0.01) were all household factors significantly associated with an increased odds of infection. Infection with STH was not significantly associated with the gastrointestinal illness (p>0.05), BMI or Hb levels; however, one third of all 2–12 year olds surveyed were found to be anaemic (i.e. Hb concentrations below 110g/l or 115g/l for children under 5 and 5 years or older, respectively), with a greater proportion of school-age children at risk. Knowledge and behaviour related to hygiene and gastrointestinal diseases varied widely and were generally not associated with STH infection. The study revealed that STH infection remains endemic in Central Java despite ongoing deworming programs. Current control efforts would benefit from being re-evaluated to determine a more effective way forward.     

Impact of child mortality and sociodemographic attributes on family size desires: some data from urban India

Using follow-up data on a sample of mothers who gave birth at a Lucknow city hospital in India, the family size ideals of the women were examined in relation to experienced and perceived levels of child mortality and socioeconomic and demographic characteristics. The fear of child mortality and their own experience tended to increase the size of family which the mothers considered to be ideal. Under the conditions of assured survival of all children born to a couple, the study mothers considered on the average 2.83 children as ideal, as compared to 3.68 under conditions of uncertain survival. The couples with a rural background thought higher numbers of children were ideal, as compared to those with an urban background. More of the females who belonged to joint families preferred fewer children compared to those in nuclear families. Within the overall mean ideal family size of 2.83, the Hindu females thought fewer children made up an ideal family than their Muslim counterparts. Further, among the Hindus, the mean number of children considered ideal varied inversely with caste status. About 44% of the illiterate females considered 4 or more children as ideal, compared to about 5% of those with education to graduate or higher levels. The educational level of the males also influenced the family size preferences of their wives which varied inversely with them. The family size ideals of the females varied significantly with their husbands' occupational status. The females who lived in relatively poor housing conditions considered higher numbers of children as ideal. The preference is for smaller families with younger mothers. The female's age at marriage is important. The females currently using birth control methods considered an average 2.72 children as ideal, in contrast to 2.98 for those who were not using any method; the difference in means is significant.     

Prevalence of pediculosis and scabies in preschool nursery children of Afyon, Turkey

Scabies and pediculosis are ubiquitous, contagious, and debilitating parasitic dermatoses. The tendency of high prevalence of pediculosis and scabies among school and preschool age children has prompted us to conduct a head louse and scabies prevalence survey among preschool nursery children in our district. A school-based, crosssectional study was performed, with 1,134 children chosen for evaluation. All cases were evaluated by physical examination and a detailed, structured questionnaire. The infestation was found in 14 (1.2%) of 1,134 children; 9 (0.8%) with pediculosis capitis and 5 (0.4%) with scabies. We found that infestations were more frequent in children with mothers whose education levels were low. This indicates the necessity of an improvement in the economic and sociocultural status of the community and the promotion of hygiene concepts and practices in order to improve health of preschool age children.     

A long-term follow-up study on the efficacy of further attenuated live measles vaccine, Biken CAM vaccine

Antibody persistence was measured in 39 children in an open community 12-13 years after immunization against measles with further attenuated live vaccine, Biken CAM. Serum samples of the children taken every two or three years after vaccination had higher, lower, or the same HI antibody titers as those in samples taken 6 weeks after vaccination. These differences reflected a decrease in the titer in some children and subclinical natural reinfection in others. However, all the children still retained detectable antibody in 12 or 13 years after vaccination, indicating long-term persistence of immunity after immunization with Biken CAM vaccine. For evaluation of the protective efficacy of the vaccine, matched controls were studied during the same period. Serological examination revealed that 97.5% of the controls were infected with measles and contracted the disease. In contrast, none of the vaccinees developed clinical infection after close contact with measles patients.     

Retinol assessment among women and children in sahelian mobile pastoralists

Micronutrient deficiencies are widespread in developing countries, particularly in remote communities such as mobile pastoralists. The nutritional and vitamin A status of this population is not well-documented in Chad. This study assessed serum retinol levels among women and children under five-year-old in nomadic and semi-nomadic pastoralist and rural-settled communities, who are similarly exposed to risk factors such as gastrointestinal parasitic infection, anaemia and emaciation. The novel method of portable fluorometry was used for the first time to measure β-carotene and retinol levels in a pastoral nomadic area. Moderate level blood retinol deficiency (<0.7?μmol/L) was observed in 5% (CI 1-11) of nomadic, 29% (CI 13-45) of semi-nomadic and 22% (CI 8-35) of sedentary women. In children, 1% (CI 0.1-4), 17% (CI 9-25) and 28% (CI 18-39), respectively, had moderate level blood retinol deficiency. In nomadic communities, women and children had blood retinol levels close to normal. Deficiency of retinol was strongly linked with lifestyle (nomadic, semi-nomadic and settled) among women and lifestyle and age among children. The results support an ecological linkage between human retinol levels and livestock milk retinol. This study shows the feasibility of portable retinol and β-carotene measurement in human blood as well as human and animal milk under remote field conditions, but the approach requires further validation.     

Rising incidence of insulin dependent diabetes in children aged under 5 years in the Oxford region: time trend analysis. The Bart's-Oxford Study Group.

OBJECTIVES: To monitor incidence of insulin dependent diabetes in children in Oxford health region since 1985, and to look for any evidence of disproportionate increase in children aged under 5. DESIGN: Primary ascertainment of cases of childhood diabetes was by prospective registration of all patients with insulin dependent diabetes diagnosed before age 15 years between 1985 and 1996 and resident in Oxford region at time of diagnosis. This was supplemented by examination of centralised hospital discharge records and death certificates. Secondary case ascertainment was by postal surveys of general practitioners in 1987 and 1996. SETTING: Area formerly administered by Oxford Regional Health Authority. SUBJECTS: 1037 children presenting with insulin dependent diabetes under age of 15 years. MAIN OUTCOME MEASURES: Incidence of insulin dependent diabetes in children aged 0-4, 5-9, and 10-14 years during 1985-95. RESULTS: Overall incidence of diabetes in children aged 0-15 was 18.6 cases/100000/year and showed an annual increase of 4% from 1985 to 1996. This was mainly due to a rapid increase in children aged 0-4 years, in whom there was an annual increase of 11% (95% confidence interval 6% to 15%, P < 0.0001), while the annual increase in those aged 5-9 was 4% (0 to 7%, P = 0.05) and in those aged 10-14 was 1% (-2% to 4%, P = 0.55). CONCLUSIONS: Incidence of insulin dependent diabetes in children aged under 5 years has risen markedly in the Oxford region over the past decade. The cause of the increase is unknown, but environmental influences encountered before birth or in early postnatal life are likely to be responsible.     

Computer simulation of Gumboro disease outbreak. IV. Epizootics obtained by mode G-4 with flock size, age and immunity changed

For the computer simulation of Gumboro disease outbreak by Model G-4 a program was written in FORTRAN. Of over twenty parameters involved in the model, the following three were used as input variables: (1) age of chickens at housing a1 (= 1 and 21); (2) size of flock at housing, N(a1) (= 100 and 1,000); and (3) geometric mean of the level of parentally conferred immunity at hatching, G(1) (= 0, 2, 8, and 32). The outputs were the graphic images demonstrating the chronological changes in a flock of innate resistance, parentally conferred immunity, and their sum, and the epizootic patterns composed of numbers of chickens at subclinical stage, clinically diseased, recovered, condemned, etc. at each age. As a result, stronger epizootics were produced at a lower level of parentally conferred immunity, and a higher age and a larger size of flocks. It was suggested that the subclinical stage might not be understood as an inapparent infection, and that a further postulate on the infection might be necessary to be introduced into this model to increase the practical utility, as well as the theoretical soundness, of this series of studies.     

Sanitation and Hygiene-Specific Risk Factors for Moderate-to-Severe Diarrhea in Young Children in the Global Enteric Multicenter Study, 2007–2011: Case-Control Study

BackgroundDiarrheal disease is the second leading cause of disease in children less than 5 y of age. Poor water, sanitation, and hygiene conditions are the primary routes of exposure and infection. Sanitation and hygiene interventions are estimated to generate a 36% and 48% reduction in diarrheal risk in young children, respectively. Little is known about whether the number of households sharing a sanitation facility affects a child''s risk of diarrhea. The objective of this study was to describe sanitation and hygiene access across the Global Enteric Multicenter Study (GEMS) sites in Africa and South Asia and to assess sanitation and hygiene exposures, including shared sanitation access, as risk factors for moderate-to-severe diarrhea (MSD) in children less than 5 y of age.Methods/FindingsThe GEMS matched case-control study was conducted between December 1, 2007, and March 3, 2011, at seven sites in Basse, The Gambia; Nyanza Province, Kenya; Bamako, Mali; Manhiça, Mozambique; Mirzapur, Bangladesh; Kolkata, India; and Karachi, Pakistan. Data was collected for 8,592 case children aged <5 y old experiencing MSD and for 12,390 asymptomatic age, gender, and neighborhood-matched controls. An MSD case was defined as a child with a diarrheal illness <7 d duration comprising ≥3 loose stools in 24 h and ≥1 of the following: sunken eyes, skin tenting, dysentery, intravenous (IV) rehydration, or hospitalization. Site-specific conditional logistic regression models were used to explore the association between sanitation and hygiene exposures and MSD. Most households at six sites (>93%) had access to a sanitation facility, while 70% of households in rural Kenya had access to a facility. Practicing open defecation was a risk factor for MSD in children <5 y old in Kenya. Sharing sanitation facilities with 1–2 or ≥3 other households was a statistically significant risk factor for MSD in Kenya, Mali, Mozambique, and Pakistan. Among those with a designated handwashing area near the home, soap or ash were more frequently observed at control households and were significantly protective against MSD in Mozambique and India.ConclusionsThis study suggests that sharing a sanitation facility with just one to two other households can increase the risk of MSD in young children, compared to using a private facility. Interventions aimed at increasing access to private household sanitation facilities may reduce the burden of MSD in children. These findings support the current World Health Organization/ United Nations Children''s Emergency Fund (UNICEF) system that categorizes shared sanitation as unimproved.     

Seroprevalence and Potential Risk Factors for Helicobacter pylori Infection in Brazilian Children

Background: Helicobacter pylori infection has been proved to be of great relevance to public health in unindustrialized countries, especially in low socioeconomic groups. Poor hygiene, deficient sanitation, and crowded conditions have been reported as risk factors for this infection. In this work, we investigated whether social and demographic characteristics were associated with anti‐H. pylori IgG antibodies in 1104 children aged 4–11 years old from Salvador, a large city located in northeastern Brazil. Methods: Standardized questionnaires were used to obtain social, demographic, and environmental data for the studied population in two periods of time (from 1997 to 2003 and in 2005). Anti‐H. pylori IgG antibodies were assessed by indirect enzyme‐linked immunosorbent assay in 2005. Results: Anti‐H. pylori IgG antibody was present in 28.7% of the children. Among the studied variables, the following were positively associated with the presence of anti‐H. pylori antibodies in multivariable analyses: age above 8 years old (OR = 1.72, 95% CI = 1.23–2.40), a larger sibling number (OR = 1.66, 95% CI = 1.26–2.18), nursery attendance (OR = 1.49, 95% CI = 1.04–2.12), location of the house at an unpaved street (OR = 2.03, 95% CI = 1.44–2.87) and absence of a flush toilet (OR = 1.32, 95% CI = 1.00–1.74). Conclusion: Our data show that H. pylori infection in children from a major Brazilian city is associated with variables indicative of a crowded environment and deficient sanitation/habitation conditions, leading to the conclusion that improvements in hygiene and social conditions may protect children against this infection.