Socioeconomic correlates of antibody levels to enteric pathogens among Israeli adolescents

Seropositivity to Shiga toxin 2 among Argentinian urban and rural residents. Association with sociodemographic and exposure factors

BACKGROUND

Shiga toxin-producing Escherichia coli (STEC) are enteric pathogens that cause hemolytic-uremic syndrome (HUS). Ruminants, especially cattle, are their main reservoir. This study describes the seroepidemiology of STEC in rural and urban populations in Argentina, a country with a high HUS incidence.

METHODS

A cross-sectional study was performed in patients without gastrointestinal symptoms. IgG antibodies against Stx2 were detected by western blotting.

RESULTS

Anti-Stx2 antibodies were detected in 14.56% of serum samples, more frequently in rural (19.38%) than urban residents (12%). Seropositivity was associated with lower socioeconomic status (SES). Among the other variables considered, thawing homemade hamburgers before cooking them, and the lack of knowledge about HUS were also associated with seropositivity. A multivariate logistic regression analysis performed with the variables that were statistically significant showed that only the SES index remained significant. As SES was measured based on several variables, we further analyzed each one of them and found that the lack of a high education level was statistically associated with seropositivity.

CONCLUSIONS

The present findings have implications for STEC prevention efforts, highlighting the importance of considering SES and risks factors linked to different SES levels when targeting consumer-level public health interventions.

Detoxified O-Specific Polysaccharide (O-SP)–Protein Conjugates: Emerging Approach in the Shigella Vaccine Development Scene

Shigella is the second most common cause of moderate to severe diarrhea among children worldwide and of diarrheal disease-associated mortality in young children in low-and middle-income countries. In spite of many years of attempts to develop Shigella vaccines, no licensed vaccines are yet available. Injectable conjugate vaccines made of the detoxified lipopolysaccharide (LPS) of S. flexneri 2a, S. sonnei, and S. dysenteriae type 1 covalently bound to protein carriers were developed in the early 1990s by John B. Robbins and Rachel Schneerson at the US National Institutes of Health. This approach was novel for a disease of the gut mucosa, at a time when live, rationally attenuated oral vaccine strains that intended to mimic Shigella infection and induce a protective local immune response were extensively investigated. Of keystone support to Shigella glycoconjugates development were the findings of a strong association between pre-existent serum IgG antibodies to S. sonnei or S. flexneri 2a LPS and a lower risk of infection with the homologous Shigella serotypes among Israeli soldiers serving in field units. In view of these findings and of the successful development of the pioneering Haemophilus influenzae type b conjugate vaccines, it was hypothesized that protective immunity may be conferred by serum IgG antibodies to the O-Specific Polysaccharide (O-SP) following parenteral delivery of the conjugates. S. sonnei and S. flexneri 2a glycoconjugates induced high levels of serum IgG against the homologous LPS in phase I and II studies in healthy volunteers. The protective efficacy of a S. sonnei detoxified LPS-conjugate was further demonstrated in field trials in young adults (74%) and in children older than three years of age (71%), but not in younger ones. The evaluation of the Shigella conjugates confirmed that IgG antibodies to Shigella LPS are correlates of protection and provided solid basis for the development of a new generation of glycoconjugates and other injectable LPS-based vaccines that are currently in advanced stages of clinical evaluation.

Serum IgG antibodies to Shigella lipopolysaccharide antigens - a correlate of protection against shigellosis

Shigella is a leading cause of diarrhea among children globally and of diarrheal deaths among children under 5 years of age in low- and middle-income countries. To date, no licensed Shigella vaccine exists. We review evidence that serum IgG antibodies to Shigella LPS represent a good correlate of protection against shigellosis; this could support the process of development and evaluation of Shigella vaccine candidates. Case-control and cohort studies conducted among Israeli soldiers serving under field conditions showed significant serotype-specific inverse associations between pre-exposure serum IgG antibodies to Shigella LPS and shigellosis incidence. The same serum IgG fraction showed a dose-response relationship with the protective efficacy attained by vaccine candidates tested in phase III trials of young adults and children aged 1-4 years and in Controlled Human Infection Model studies and exhibited mechanistic protective capabilities. Identifying a threshold level of these antibodies associated with protection can promote the development of an efficacious vaccine for infants and young children.

Risk factors for sporadic infection with Salmonella Infantis: a matched case-control study

This matched case-control study investigated the risk factors for sporadic Salmonella Infantis infection in 263 affected children and 263 age-, gender- and neighbourhood-matched controls. Information about exposure to potential risk factors was obtained via telephone interview and evaluated by conditional logistic regression analysis. Age groups ≤ 1 year (n=77) and >1 year (n = 186) were analysed separately. Of those aged ≤ 1 year, breastfeeding was a significant protective factor against infection [matched odds ratio (mOR) 0.24, 95% confidence interval (CI) 0.10-0.59, P < 0.01]. In the older group, consumption of eggs (mOR 1.87, 95% CI 1.00-3.49, P = 0.05) was a significant risk factor and thawing chicken in water (mOR 2.55, 95% CI 0.94-6.91, P = 0.07) was borderline risk factor, while consumption of carrots (mOR 0.46, 95% CI 0.26-0.83, P < 0.01), drinking tap water (mOR 0.44, 95% CI 0.22-0.85, P = 0.02), religious lifestyle (mOR 0.40, 95% CI 0.21-0.74, P < 0.01) and having a high number of children in the household (mOR 0.72, 95% CI 0.58-0.88, P < 0.01) were significant protective factors. Consumers should avoid eating undercooked eggs and food handlers should be educated regarding proper handling and cooking of eggs. Breastfeeding should be strongly encouraged by public health authorities. The public must be educated on stringent hygiene practices, especially proper cooking of eggs to reduce infection rates.

The changing panorama of bacterial enteric infections

We studied the age-specific population-based incidence of bacterial enteric infections caused by Shigella, Salmonella and Campylobacter, in Jerusalem. During 1990–2008, 32 408 cases were reported (incidence rate 232·1/100 000 per annum). The patterns of Shigella (47·4% of cases), Salmonella (34·4%) and Campylobacter (18·2%) infections evolved noticeably. Campylobacter rates increased from 15·0 to 110·8/100 000 per annum. Salmonella rates increased from 74·2 to 199·6/100 000 in 1995 then decreased to 39·4/100 000. Shigella showed an endemic/epidemic pattern ranging between 19·7 and 252·8/100 000. Most patients (75%) were aged <15 years; children aged <5 years comprised 56·4% of cases, despite accounting for only 12·9% of the population. Campylobacter was the predominant organism in infants aged <1 year and Shigella in the 1–4 years group. The hospitalization rates were: Shigella, 1·8%; Campylobacter, 2·3%; Salmonella, 6·9%. Infants were 2·2 times more likely to be hospitalized than children aged 1–14 years (P=0·001). Household transmission occurred in 21·2% of Shigella cases compared with 5% in the other bacteria.

An ecological analysis of sociodemographic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties

Identifying county-level sociodemographic and economic factors associated with the incidence of enteric disease may provide new insights concerning the dynamics of community transmission of these diseases as well as opportunities for prevention. We used data from the National Notifiable Diseases Surveillance System, the U.S. Census Bureau, and the Health Resources and Services Administration to conduct an ecological analysis of 26 sociodemographic and economic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties for the period 1993 to 2002. Our study indicates that race, ethnicity, place of residence, age, educational attainment, and poverty may affect the risk of acquiring one of these enteric bacterial diseases. The lack of specificity of information regarding salmonellae and shigellae serotypes may have led to less specific associations between community-level determinants and reported incidence of those diseases. Future ecological analyses should use serotype-specific data on incidence, which may be available from laboratory-based surveillance systems.

Intussusception in children in Southern Israel: disparity between 2 populations

BACKGROUND

Intussusception has been associated with 1 rotavirus vaccine. Our objective was to determine intussusception rates in children in southern Israel during a 15-year period before the introduction of new rotavirus vaccines.

METHODS

All children born at the Soroka Medical Center are hospitalized in that center, enabling population-based studies. Two populations reside in Southern Israel: the Jewish population (comparable to a Western population) and the Bedouin population (comparable to a developing population). Retrospectively, all children <5 years of age admitted with ICD-9 code for intussusception were recorded as well as their demographic and clinical data.

RESULTS

During 1990-2004, 316 patients with intussusception [241 (76%) Jewish children and 75 (24%) Bedouin children] were recorded. None died. The mean annual rates for children <5 years (per 100,000) were 49.3 +/- 17.4 and 18.9 +/- 9.6 for Jewish and Bedouin children, respectively (P < 0.001), with a significant increase in intussusception rates during the study period in Bedouin (P = 0.022), but not in Jewish children (P = 0.38). Mean annual intussusception rates per 100,000 for children <12 months were 199.6 +/- 5.2 and 66.8 +/- 44.1 for Jews and Bedouin infants, respectively (P < 0.001). In Bedouin children, a significantly higher number of cases were observed from March to May, whereas no seasonality pattern was noted in Jewish children. Negative correlation between intussusception and gastroenteritis was found in Bedouin infants during the summer months, whereas no such correlation was found in Jewish infants.

CONCLUSIONS

Pre-rotavirus vaccination intussusception rate is high especially among Jewish infants in Southern Israel. Intussusception rates increased significantly during the study period in Bedouin infants.