International Centre for Diarrhoeal Disease Research, Bangladesh

About: International Centre for Diarrhoeal Disease Research, Bangladesh is a facility organization based out in Dhaka, Bangladesh. It is known for research contribution in the topics: Population & Vibrio cholerae. The organization has 3103 authors who have published 5238 publications receiving 226880 citations. The organization is also known as: SEATO Cholera Research Laboratory & Bangladesh International Centre for Diarrhoeal Disease Research.

Sex-specific effects of early life cadmium exposure on DNA methylation and implications for birth weight

Abstract: Dietary cadmium exposure was recently found to alter DNA methylation in adults, but data on effects early in life are lacking. Our objective was to evaluate associations between prenatal cadmium exposure, DNA methylation and birth weight. In total 127 mother-child pairs from rural Bangladesh were studied. For comparison, we included 56 children at 4.5 y. Cadmium concentrations in mothers’ blood (gestational week 14) and children’s urine were measured by ICPMS. Global DNA methylation was analyzed by Infinium HumanMethylation450K BeadChip in cord blood and children’s blood. Maternal cadmium exposure was associated with cord blood DNA methylation (p-value 0.50), whereas most associations in girls were inverse; only 29% were positive (rS > 0.45). In girls we found overrepresentation of methylation changes in genes associated with organ development, morphology and mineralization of bone, whereas changes in boys were found in cell death-related genes. Several individual CpG sites that were positively associated with cadmium were inversely correlated with birth weight, although none statistically significant after correction for multiple comparisons. The associations were, however, fairly robust in multivariable-adjusted linear regression models. We identified CpG sites that were significantly associated with cadmium exposure in both newborns and 4.5-y-old children. In conclusion, cadmium exposure in early life appears to alter DNA methylation differently in girls and boys. This is consistent with previous findings of sex-specific cadmium toxicity. Cadmium-related changes in methylation were also related to lower birth weight.

Nutrition: Basis for Healthy Children and Mothers in Bangladesh

Abstract: Recent data from the World Health Organization showed that about 60% of all deaths, occurring among children aged less than five years (under-five children) in developing countries, could be attributed to malnutrition. It has been estimated that nearly 50.6 million under-five children are malnourished, and almost 90% of these children are from developing countries. Bangladesh is one of the countries with the highest rate of malnutrition. The recent baseline survey by the National Nutrition Programme (NNP) showed high rates of stunting, underweight, and wasting. However, data from the nutrition surveillance at the ICDDR, B hospital showed that the proportion of children with stunting, underweight, and wasting has actually reduced during 1984–2005. Inappropriate infant and young child-feeding practices (breastfeeding and complementary feeding) have been identified as a major cause of malnutrition. In Bangladesh, although the median duration of breastfeeding is about 30 months, the rate of exclusive breastfeeding until the first six months of life is low, and practice of appropriate complementary feeding is not satisfactory. Different surveys done by the Bangladesh Demographic and Health Survey, United Nations Children's Fund (UNICEF), and Bangladesh Breastfeeding Foundation (BBF) showed a rate of exclusive breastfeeding to be around 32-52%, which have actually remained same or declined over time. The NNP baseline survey using a strict definition of exclusive breastfeeding showed a rate of exclusive breastfeeding (12.8%) until six months of age. Another study from the Abhoynagar field site of ICDDR, B reported the prevalence of exclusive breastfeeding to be 15% only. Considerable efforts have been made to improve the rates of exclusive breastfeeding. Nationally, initiation of breastfeeding within one hour of birth, feeding colostrum, and exclusive breastfeeding have been promoted through the Baby-Friendly Hospital Initiative (BFHI) implemented and supported by BBF and UNICEF respectively. Since most (87-91%) deliveries take place in home, the BFHI has a limited impact on the breastfeeding practices. Results of a few studies done at ICDDR, B and elsewhere in developing countries showed that the breastfeeding peer-counselling method could substantially increase the rates of exclusive breastfeeding. Results of a study in urban Dhaka showed that the rate of exclusive breastfeeding was 70% among mothers who were counselled compared to only 6% who were not counselled. Results of another study in rural Bangladesh showed that peer-counselling given either individually or in a group improved the rate of exclusive breastfeeding from 89% to 81% compared to those mothers who received regular health messages only. This implies that scaling up peer-counselling methods and incorporation of breastfeeding counselling in the existing maternal and child heath programme is needed to achieve the Millennium Development Goal of improving child survival. The recent data showed that the prevalence of starting complementary food among infants aged 6-9 months had increased substantially with 76% in the current dataset. However, the adequacy, frequency, and energy density of the complementary food are in question. Remarkable advances have been made in the hospital management of severely-malnourished children. The protocolized management of severe protein-energy malnutrition at the Dhaka hospital of ICDDR, B has reduced the rate of hospital mortality by 50%. A recent study at ICDDR, B has also documented that home-based management of severe protein-energy malnutrition without follow-up was comparable with a hospital-based protocolized management. Although the community nutrition centres of the NNP have been providing food supplementation and performing growth monitoring of children with protein-energy malnutrition, the referral system and management of complicated severely-malnourished children are still not in place.

Prevalence of G2P[4] and G12P[6] rotavirus, Bangladesh.

Abstract: Approximately 20,000 stool specimens from patients with diarrhea visiting an urban and a rural hospital in Bangladesh during January 2001–May 2006 were tested for group A rotavirus antigen, and 4,712 (24.0%) were positive. G and P genotyping was performed on a subset of 10% of the positive samples (n = 471). During the 2001–2005 rotavirus seasons, G1P[8] (36.4%) and G9P[8] (27.7%) were the dominant strains, but G2[4] and G12P[6] were present in 15.4% and 3.1% of the rotavirus-positive patients, respectively. During the 2005–06 rotavirus season, G2P[4] (43.2%) appeared as the most prevalent strain, and G12P[6] became a more prevalent strain (11.1%) during this season. Because recently licensed rotavirus vaccines are specific for only P[8], these vaccines may not perform well in settings where non-P[8] types are prevalent.

Virulence genes in environmental strains of Vibrio cholerae.

Abstract: The virulence of a pathogen is dependent on a discrete set of genetic determinants and their well-regulated expression. The ctxAB and tcpA genes are known to play a cardinal role in maintaining virulence in Vibrio cholerae, and these genes are believed to be exclusively associated with clinical strains of O1 and O139 serogroups. In this study, we examined the presence of five virulence genes, including ctxAB and tcpA, as well as toxR and toxT, which are involved in the regulation of virulence, in environmental strains of V. cholerae cultured from three different freshwater lakes and ponds in the eastern part of Calcutta, India. PCR analysis revealed the presence of these virulence genes or their homologues among diverse serotypes and ribotypes of environmental V. cholerae strains. Sequencing of a part of the tcpA gene carried by an environmental strain showed 97.7% homology to the tcpA gene of the classical biotype of V. cholerae O1. Strains carrying the tcpA gene expressed the toxin-coregulated pilus (TCP), demonstrated by both autoagglutination analysis and electron microscopy of the TCP pili. Strains carrying ctxAB genes also produced cholera toxin, determined by monosialoganglioside enzyme-linked immunosorbent assay and by passage in the ileal loops of rabbits. Thus, this study demonstrates the presence and expression of critical virulence genes or their homologues in diverse environmental strains of V. cholerae, which appear to constitute an environmental reservoir of virulence genes, thereby providing new insights into the ecology of V. cholerae.