Showing papers by "International Centre for Diarrhoeal Disease Research, Bangladesh published in 1999"

Case-Control Study of Enteropathogens Associated with Childhood Diarrhea in Dhaka, Bangladesh

Abstract: The International Centre for Diarrhoeal Disease Research, Bangladesh, is a major center for research into diarrheal diseases. The center treats more than 100,000 patients a year. To obtain useful information representative of all patients, a surveillance system in which a 4% systematic sample of all patients is studied in detail, including etiological agents of diarrhea, was installed in October 1979. The first paper on etiology for the surveillance patients was published in 1982, which identified a potential enteric pathogen in 66% of patients. In subsequent years, several new agents of diarrhea have been identified. To assess the importance of a broader spectrum of diarrheal agents including the ones identified relatively recently, we studied 814 children with diarrhea. The children were up to 5 years of age and were part of the surveillance system. They were matched with an equal number of community controls without diarrhea. The study was conducted from February 1993 to June 1994. A potential enteric pathogen was isolated from 74.8% of diarrheal children and 43.9% of control children (P = 0.0001). Even though the first study was not a case-control study, it identified rotavirus, Campylobacter jejuni, enterotoxigenic Escherichia coli, Shigella spp. , and Vibrio cholerae O1 as major pathogens. The present study identified these pathogens as being significantly associated with diarrhea. In addition, the study also identified six additional agents, including enteropathogenic E. coli, Aeromonas spp., V. cholerae O139, enterotoxigenic Bacteroides fragilis, Clostridium difficile, and Cryptosporidium parvum, as being significantly associated with diarrhea. Plesiomonas shigelloides, Salmonella spp., diffusely adherent E. coli, enteroaggregative E. coli, Entamoeba histolytica, and Giardia lamblia were not significantly associated with diarrhea. Enteroinvasive E. coli, enterohemorrhagic E. coli, and Cyclospora cayetanensis were not detected in any of the children. The major burden of diseases due to most pathogens occurred in the first year of life. As in the previous study, seasonal patterns were seen for diarrhea associated with rotavirus, V. cholerae, and enterotoxigenic E. coli, and infections with multiple pathogens were common. With a few exceptions, these findings are in agreement with those from other developing countries. This knowledge of a broader spectrum of etiological agents of diarrhea in the surveillance patients will help us plan studies into various aspects of diarrheal diseases in this population.

Evidence of High-Frequency Genomic Reassortment of Group A Rotavirus Strains in Bangladesh: Emergence of Type G9 in 1995

Abstract: We characterized 1,534 rotavirus (RV) strains collected in Bangladesh from 1992 to 1997 to assess temporal changes in G type and to study the most common G and P types using reverse transcription-PCR, oligonucleotide probe hybridization, and monoclonal antibody-based enzyme immunoassay. Results from this study combined with our previous findings from 1987 to 1991 (F. Bingnan et al., J. Clin. Microbiol. 29:862-868, 1991, and L. E. Unicomb et al., Arch. Virol. 132:201-208, 1993) (n = 2,515 fecal specimens) demonstrated that the distribution of the four major G types varied from year to year, types G1 to G4 constituted 51% of all strains tested (n = 1,364), and type G4 was the most prevalent type (22%), followed by type G2 (17%). Of 351 strains tested for both G and P types, three globally common types, type P[8], G1, type P[4], G2, and type P[8], G4, comprised 45% (n = 159) of the strains, although eight other strains were circulating during the study period. Mixed G and/or P types were found in 23% (n = 79) of the samples tested. Type G9 RVs that were genotype P[6] and P[8] with both long and short electrophoretic patterns emerged in 1995. The finding of five different genotypes among G9 strains, of which three were frequently detected, suggests that they may have an unusual propensity for reassortment that exceeds that found among the common G types. We also detected antigenic changes in serotypes G2 and G4 over time, as indicated by the loss of reactivity with standard typing monoclonal antibodies. Our data suggest that a vaccine must provide protection against type G9 RVs as well as against the four major G types because G9 strains constituted 16% (n = 56) of the typeable RV strains and have predominated since 1996.

PCR Detection, Characterization, and Distribution of Virulence Genes in Aeromonas spp.

Abstract: We found 73.1 to 96.9% similarity by aligning the cytolytic enterotoxin gene of Aeromonas hydrophila SSU (AHCYTOEN; GenBank accession no. M84709) against aerolysin genes of Aeromonas spp., suggesting the possibility of selecting common primers. Identities of 90 to 100% were found among the eight selected primers from those genes. Amplicons obtained from Aeromonas sp. reference strains by using specific primers for each gene or a cocktail of primers were 232 bp long. Of hybridization group 4/5A/5B (HG4/5A/5B), HG9, and HG12 or non-Aeromonas reference strains, none were positive. PCR-restriction fragment length polymorphism (PCR-RFLP) with HpaII yielded three types of patterns. PCR-RFLP 1 contained two fragments (66 and 166 bp) found in HG6, HG7, HG8, HG10, and HG11. PCR-RFLP 2 contained three fragments (18, 66, and 148 bp) found in HG1, HG2, HG3, and HG11. PCR-RFLP 3, with four fragments (7, 20, 66, and 139 bp), was observed only in HG13. PCR-amplicon sequence analysis (PCR-ASA) revealed three main types. PCR-ASA 1 had 76 to 78% homology with AHCYTOEN and included strains in HG6, HG7, HG8, HG10, and HG11. PCR-ASA 2, with 82% homology, was found only in HG13. PCR-ASA 3, with 91 to 99% homology, contained the strains in HG1, HG2, HG3, and HG11. This method indicated that 37 (61%) of the 61 reference strains were positive with the primer cocktail master mixture, and 34 (58%) of 59 environmental isolates, 93 (66%) of 141 food isolates, and 100 (67%) of 150 clinical isolates from around the world carried a virulence factor when primers AHCF1 and AHCR1 were used. In conclusion, this PCR-based method is rapid, sensitive, and specific for the detection of virulence factors of Aeromonas spp. It overcomes the handicap of time-consuming biochemical and other DNA-based methods.

Maternal vitamin A or β-carotene supplementation in lactating bangladeshi women benefits mothers and infants but does not prevent subclinical deficiency

Abstract: The effects of maternal postpartum vitamin A or beta-carotene supplementation on maternal and infant serum retinol concentrations, modified relative dose-response (MRDR) ratios and breast milk vitamin A concentrations were assessed during a community-based trial in Matlab, Bangladesh. At 1-3 wk postpartum, women were randomly assigned to receive either (1) a single dose of 200,000 international units [60,000 retinol equivalents (RE)] vitamin A followed by daily placebos (n = 74), (2) daily doses of beta-carotene [7.8 mg (1300 RE)] (n = 73) or (3) daily placebos (n = 73) until 9 mo postpartum. Compared to placebos, vitamin A supplementation resulted in lower maternal MRDR ratios (i.e., increased liver stores) and higher milk vitamin A concentrations at 3 mo, but these improvements were not sustained. The beta-carotene supplementation acted more slowly, resulting in milk vitamin A concentrations higher than the placebo group only at 9 mo. Irrespective of treatment group, over 50% of women produced milk with low vitamin A concentrations ( /=0. 06. We conclude that while both interventions were beneficial, neither was sufficient to correct the underlying subclinical vitamin A deficiency in these women nor to bring their infants into adequate vitamin A status.

The Immunization Programme in Bangladesh: Impressive Gains in Coverage, But Gaps Remain

Abstract: The paper reviews the achievements in tetanus immunization coverage and child immunization in Bangladesh. It uses data from the 1993-94 Bangladesh Demographic and Health Survey to identify and examine the programmatic and non-programmatic factors that influence the coverage of tetanus (TT) immunization during pregnancy, and full immunization among children 12-23 months old in rural Bangladesh. The purpose of this analysis is to identify the areas that need further programme attention. The logistic regression results show that the coverage of TT immunization was significantly associated with proximity to outreach clinics and the presence of a health worker in the community. Home visits by health/family planning fieldworkers and the proximity to outreach clinics had larger influences on TT coverage of poorer households compared to those better-off. The effect of distance to static clinics varied by regions. Among children, full immunization coverage (coverage of all of BCG, DPT1, DPT2, DPT3, Polio1 Polio2, Polio3) was significantly associated with distance to outreach clinics, the greater the distance to the clinics, the less the likelihood of immunization.

The Bangladesh Fertility Decline: An Interpretation

Abstract: Bangladeshs fertility transition has attracted more theoretical interest than any other contemporary transition. Among countries where there has not been a coercive government family planning program Bangladesh is the poorest to have a total fertility rate under 5 births/woman. Only Vietnam has a fertility level similar to Bangladeshs at a comparably low per capita income but its per capita purchasing power is 60% higher its mortality is much lower and its family planning program is somewhat coercive. A World Bank study on the determinants of reproductive change in Bangladesh determined that no change was needed in the levels of economic development urbanization womens employment or education for the family planning program to succeed. Rather sustained political commitment at the highest levels to an effective family planning program was the key to Bangladeshs successful fertility transition. The authors investigated whether the experimental conditions of the Bank study were good enough to warrant the findings. Data were drawn from Bangladesh statistical information and a joint research program on fertility decline conducted by the Extension Project of the International Center for Diarrheal Disease Research Bangladesh and the Australian National University.

Food as a vehicle of transmission of cholera.

Abstract: Cholera has been recognized as a killer disease since earliest time. Since 1817, six pandemics have swept over the world, and the seventh one is in progress. The disease is caused by infection of the small intestine by Vibrio cholerae O1 and O139 and is characterized by massive acute diarrhoea, vomiting, and dehydration: death occurs in severe, untreated cases. Cholera is a highly contagious disease, and is transmitted primarily by ingestion of faecally-contaminated water by susceptible persons. Besides water, foods have also been recognized as an important vehicle for transmission of cholera. Foods are likely to be faecally contaminated during preparation, particularly by infected food handlers in an unhygienic environment. The physicochemical characteristics of foods that support survival and growth of V. cholerae O1 and O139 include high-moisture content, neutral or an alkaline pH, low temperature, high-organic content, and absence of other competing bacteria. Seafoods, including fish, shellfish, crabs, oysters and clams, have all been incriminated in cholera outbreaks in many countries, including the United States and Australia. Contaminated rice, millet gruel, and vegetables have also been implicated in several outbreaks. Other foods, including fruits (except sour fruits), poultry, meat, and dairy products, have the potential of transmitting cholera. To reduce the risk of food-borne transmission of cholera, it is recommended that foods should be prepared, served, and eaten in an hygienic environment, free from faecal contamination. Proper cooking, storing, and re-heating of foods before eating, and hand-washing with safe water before eating and after defaecation are important safety measures for preventing food-borne transmission of cholera.

Epidemiology of child deaths due to drowning in Matlab, Bangladesh.

Abstract: BACKGROUND: Although the recent decline in child mortality in Bangladesh is remarkable, death from causes other than infectious diseases and malnutrition remains an important component of child mortality. Death from drowning of children can be expected to be a problem in Bangladesh given the geographical features of the country. OBJECTIVE: The objectives of this study are to determine the trend, pattern, and correlates of drowning deaths. METHODS: Data are presented on deaths of children (1-4 years) due to drowning derived from a longitudinal, population-based surveillance system in operation in a rural area of Bangladesh in 1983-1995. Moreover, a case-control study was carried out to identify the risk factors associated with drowning. RESULTS: Deaths due to drowning ranged from about 10% to 25% of child deaths during 1983-1995. The absolute risk of dying from drowning remained almost the same over the study period but the proportion of drownings to all causes of death has increased. Drowning is especially prevalent in the second year of life. Age of the mother and parity have a significant impact on drowning. The risk of dying from drowning increases with the age of mother and much more sharply with the number of living children in the family. Two socioeconomic variables did not have an influence on the risk of drowning. CONCLUSIONS: A substantial proportion of child deaths could be averted if parents and other close relatives paid more attention to the safety of children. The Child Health Programme of the Ministry of Health and Family Welfare of Bangladesh should develop health education programmes for villagers alerting them to the dangers of drowning and measures to prevent it.A study based upon verbal autopsies conducted in a sample of children who died in Bangladesh during 1989-92 found that approximately 21% of deaths among children aged 1-4 years were due to drowning. Such mortality may be expected in Bangladesh, for its villages are usually surrounded and intersected by canals and rivers, and there are many ponds surrounding households which are used for bathing and washing year round. Children also play in these bodies of water, and most villages are inundated by the monsoon for several months each year. Drawn from the Matlab Demographic Surveillance System (DSS) operated by the International Center for Diarrheal Disease Research, Bangladesh (ICDDR,B), data are presented on the mortality of children aged 1-4 years due to drowning in Matlab thana, a rural area of Bangladesh, during 1983-95. 10-25% of child deaths during 1983-95 were due to drowning. The absolute risk of dying from drowning remained almost the same over the study period, but the proportion of drownings to all causes of death increased. Drowning is especially prevalent during the second year of life. Mother's age and parity significantly affect drowning, with the risk of dying from drowning increasing with mother's age and far more sharply with the number of living children in the family. Maternal education and dwelling space had no influence upon the risk of drowning. A major portion of these deaths could be averted if parents and other close relatives paid more attention to child safety.

Impact of zinc supplementation on subsequent growth and morbidity in Bangladeshi children with acute diarrhoea.

Abstract: Objective: To assess the impact of zinc supplementation during acute diarrhoea on subsequent growth and morbidity in malnourished young children. Design: Double blind randomized controlled clinical trial Setting: International Centre for Diarrhoeal Disease Research, Bangladesh. Subjects: Sixty-five children aged 3–24 months with acute diarrhoea for less than 3 d. Intervention: Either elemental zinc (20 mg/d) in a multivitamin syrup or multivitamin syrup alone divided in three divided daily doses for a period of two weeks. Children were followed up weekly at home to assess subsequent growth and morbidity for a period of eight weeks. Main outcome measures: Gain in length and body weight and reduction in diarrhoea and respiratory tract infection. Results: During the follow-up, zinc supplemented children showed significantly greater cumulative length gain (18.9 mm vs 14.5 mm, P<0.03) and comparable body weight gain than the children of the control group. Subsequent length gain was not correlated with initial height in the zinc-supplemented group (r=−0.13), P=0.5), but was significantly correlated in the control group (r=-0.6, P<0.0007). Zinc-supplemented and stunted children ( ≤ 90% length for age n=18) experienced significantly fewer episodes of diarrhoea (0.07 vs 0.6, P 0.05) and respiratory illness (1.0 vs 2.4, P<0.01) compared to the control group. The underweight children (≤ 71% weight/age n=38) receiving zinc-supplementation also had fewer episodes of diarrhoea (0.4 vs 1.0, P<0.04) and shorter duration of diarrhoeal episodes (1.0 vs 3.0 d, P<0.04) compared to their counterparts in the control group. Conclusion: These results suggest that a short course of zinc supplementation to malnourished children during acute diarrhoea reduces growth-faltering and diarrhoeal and respiratory morbidity during subsequent two months. Sponsorship: Wellcome Trust.

Lysogenic Conversion of Environmental Vibrio mimicus Strains by CTXΦ

Abstract: The filamentous bacteriophage CTXPhi, which encodes cholera toxin (CT) in toxigenic Vibrio cholerae, is known to propagate by infecting susceptible strains of V. cholerae by using the toxin coregulated pilus (TCP) as its receptor and thereby causing the origination of new strains of toxigenic V. cholerae from nontoxigenic progenitors. Besides V. cholerae, Vibrio mimicus strains which are normally TCP negative have also been shown to occasionally produce CT and cause diarrhea in humans. We analyzed nontoxigenic V. mimicus strains isolated from surface waters in Bangladesh for susceptibility and lysogenic conversion by CTXPhi and studied the expression of CT in the lysogens by using genetically marked derivatives of the phage. Of 27 V. mimicus strains analyzed, which were all negative for genes encoding TCP but positive for the regulatory gene toxR, 2 strains (7.4%) were infected by CTX-KmPhi, derived from strain SM44(P27459 ctx::km), and the phage genome integrated into the host chromosome, forming stable lysogens. The lysogens spontaneously produced infectious phage particles in the supernatant fluids of the culture, and high titers of the phage could be achieved when the lysogens were induced with mitomycin C. This is the first demonstration of lysogenic conversion of V. mimicus strains by CTXPhi. When a genetically marked derivative of the replicative form of the CTXPhi genome carrying a functional ctxAB operon, pMSF9.2, was introduced into nontoxigenic V. mimicus strains, the plasmid integrated into the host genome and the strains produced CT both in vitro and inside the intestines of adult rabbits and caused mild-to-severe diarrhea in rabbits. This suggested that in the natural habitat infection of nontoxigenic V. mimicus strains by wild-type CTXPhi may lead to the origination of toxigenic V. mimicus strains which are capable of producing biologically active CT. The results of this study also supported the existence of a TCP-independent mechanism for infection by CTXPhi and showed that at least one species of Vibrio other than V. cholerae may contribute to the propagation of the phage.

Central Nervous System Manifestations of Childhood Shigellosis: Prevalence, Risk Factors, and Outcome

Abstract: Background and Objective. Alterations in consciousness, including seizures, delirium, and coma, are known to occur during Shigella infection. Previous reports have suggested that febrile convulsions and altered consciousness are more common during shigellosis than with other childhood infections. Those reports, however, have been from locations where S dysenteriae type 1 was not common, thus making it difficult to assess the specific contribution that S dysenteriae type 1 infection, and Shiga toxin, might make to the pathogenesis of altered consciousness in children with shigellosis. In this study we seek to determine the prevalence, risk factors, and outcome of altered consciousness in children with shigellosis in Bangladesh, a country where infection with all four species of Shigella is common. We particularly focus on the importance of metabolic abnormalities, which we have previously shown to be a common feature of shigellosis in this population. Methods. This study was conducted at the Diarrhea Treatment Centre of the International Centre for Diarrhoeal Disease Research, Bangladesh in Dhaka, Bangladesh, which provides care free of charge to persons with diarrhea. During 1 year, a study physician identified all inpatients infected with Shigella by checking the logs of the Clinical Microbiology Laboratory daily. Study physicians obtained demographic and historical information by reviewing the patient charts and by interviewing patients, or their parents or guardians, to confirm or complete the history of illness obtained on admission. Patients were categorized as being conscious or unconscious based on a clinical scale; having a seizure documented in the hospital; or having a seizure by history during the current illness that was not witnessed by medical personnel. Patient outcome was classified as discharged improved, discharged against medical advice, transferred to another health facility, or died in the Treatment Centre. Laboratory examinations were ordered at the discretion of the attending physician; all such information was recorded on the study form. Clinical management was by the attending physician. Factors independently predictive of a documented seizure, or of unconsciousness, were determined using a multiple logistic regression analysis. For this analysis variables associated with unconsciousness or a documented seizure in the analysis of variance or χ 2 analyses were entered into the regression equation and eliminated in a backward stepwise fashion if the probability associated with the likelihood ratio statistic exceeded .10. Results. During this 1-year study, 83 402 persons with diarrhea came to the Treatment Centre for care, and 6290 patients were admitted to the inpatient unit. Shigella was isolated from a stool or rectal swab sample of 863 (13.7%) of the inpatients. Seventy-one (8%) of the inpatients with shigellosis were ≥15 years old; 61 (86%) were conscious; 10 (14%) were unconscious; none had either a documented seizure or a seizure by history during this illness. Seven hundred ninety-two patients were Clinical features that are known to cause altered consciousness—fever, severe dehydration, hypoglycemia, hyponatremia, or meningitis—were present in 38 (92.7%) of the 41 patients in whom a seizure was witnessed and in 67 (91.8%) of the 73 patients who were unconscious. Nineteen (46.3%) of the patients who had a seizure documented had two of these five features, 4 (9.8%) had three, and 1 (2.4%) had four of these features; among unconscious patients two of the features were present in 25 (34.2%) and three in 2 (2.7%). In a multiple regression analysis factors independently associated with a documented seizure in patients Shigella and either the occurrence of seizures or altered consciousness. Patients who were unconscious (death rate 48%) or had a documented seizure (death rate (29%) were at significantly increased risk of death compared with conscious patients (death rate 6%) or patients who had a seizure by history (no deaths). There were no deaths among patients 15 years or older. Conclusions. This study had a substantially larger number of patients than any of the previously published clinical studies on seizures or altered consciousness during shigellosis. The results of this study suggest that seizures in shigellosis in the population studied occur in an age group—children 5 years of age or less—known to be at increased risk of seizures from fever or metabolic alterations. This study also suggests that, at least in the majority of these inpatients, altered consciousness is not related to Shiga toxin, which is produced in appreciable amounts only by the S dysenteriae type 1 serotype. Direct infection of the central nervous system also was not a major cause of altered consciousness in these patients. Both diminished consciousness and documented seizures are associated with a poor outcome in Bangladeshi children with shigellosis. Prompt attention to fever reduction and metabolic alterations may help reduce these potentially lethal complications, but often this is not easy to accomplish in the poor countries where shigellosis is endemic.

Prototypal diarrheagenic strains of Hafnia alvei are actually members of the genus Escherichia.

Abstract: We analyzed five bacterial strains, designated 19982, 9194, 10457, 10790, and 12502, that were isolated from stool specimens of individuals with diarrheal illness by the International Centre for Diarrhoeal Disease Research in Dhaka, Bangladesh (M. J. Albert, S. M. Faruque, M. Ansaruzzaman, M. M. Islam, K. Haider, K. Alam, I. Kabir, and R. Robins-Browne, J. Med. Microbiol. 37:310–314, 1992). The strains were initially identified as Hafnia alvei with a commercial identification system and were reported to contain the eae gene of enteropathogenic Escherichia coli. Results of conventional biochemical analyses, testing of susceptibility to cephalothin, lysis by a Hafnia-specific phage, and amplification of the outer membrane protein gene phoE with species-specific primers support the identification of these strains as members of the genus Escherichia rather than Hafnia alvei. These strains varied from typical E. coli strains by their inability to produce acid from lactose or d-sorbitol and failure to elaborate the enzyme β-d-glucuronidase. PCR analysis confirmed previous findings that the strains were positive for the eae gene and negative for other virulence markers present among recognized categories of diarrheagenic E. coli. Our findings support the hypothesis that these strains are a new category of diarrheagenic isolates belonging to the genus Escherichia and illustrate the importance of using multiple methodologies when identifying new bacterial agents of diarrheal disease.

Immune Response of Children Who Develop Persistent Diarrhea following Rotavirus Infection

Abstract: A prospective study was conducted with Bangladeshi children with rotavirus (RV) diarrhea to assess whether nutritional and clinical parameters, RV serotypes, levels of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-alpha), and gamma interferon (IFN-gamma), and RV-specific antibody titers in plasma and stool were associated with the development of persistent diarrhea. Children with watery diarrhea for 6 to 8 days, selected from the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), were enrolled in the study and monitored until diarrhea improved. Children were classified as having acute diarrhea (AD) if diarrhea resolved within 14 days of onset and as having persistent diarrhea (PD) if diarrhea persisted for more than 14 days after onset. Uninfected, control children (n = 13) from the Nutrition Follow-Up Unit of ICDDR,B were also enrolled. Of the 149 children with diarrhea enrolled, 29 had diarrhea with RV alone, of which 19 had AD and 10 developed PD. Samples of stool and blood were collected from all children on enrollment. Stool samples were collected again from children when they developed PD. Of the 10 children who had an initial RV infection and then developed PD, only one had persistent RV infection. Plasma levels of IL-10 and TNF-alpha were higher in children with diarrhea compared to uninfected controls but were similar in children with AD and PD. Plasma IFN-gamma levels were higher in children who developed PD than in those with AD (P = 0.008) or uninfected controls (P = 0.001). In stools, the levels of TNF-alpha, the only cytokine detected, were similar in the three groups of children. RV-specific immunoglobulin G (IgG) titers in plasma were higher in uninfected children than in those with AD (P < 0.001) or PD (P = 0.024) but titers were similar in children with AD and PD. RV-specific IgA titers in plasma and stool were similar in the three groups of children. From all observed parameters, only elevated plasma IFN-gamma levels were associated with subsequent development of PD. However, a larger sample size is necessary to substantiate this observation.

Lipopolysaccharide- and Cholera Toxin-Specific Subclass Distribution of B-Cell Responses in Cholera

Abstract: The immunoglobulin subclass responses to homologous lipopolysaccharide (LPS) and to cholera toxin (CT) in adult patients infected with Vibrio cholerae O1 and V. cholerae O139 were studied. LPS-specific antibody-secreting cells (ASC) of both the immunoglobulin A1 (IgA1) and IgA2 subclasses were seen, with the IgA1 ASC response predominating in both V. cholerae O1- and O139-infected patients. For antibodies in plasma, by day 11 after onset of disease, all V. cholerae O1- infected patients responded to homologous LPS with the IgA1 subclass (P = 0.001), whereas fewer (68%) responded with the IgA2 subclass (P = 0.007). About 89% of V. cholerae O139-infected patients responded with the IgA1 subclass (P = 0.003), and only 21% responded with the IgA2 subclass (not significant [NS]). Both groups of cholera patients showed significant increases in LPS-specific IgG1, IgG2, and IgG3 antibodies in plasma. In feces, the response to homologous LPS occurred in both groups of patients with the IgA1 and IgA2 subclasses, with 55 to 67% of patients showing a positive response. V. cholerae O1- and O139-infected patients showed CT-specific ASC responses of the different IgG and IgA subclasses in the circulation, and the pattern followed the order IgG1 > IgA1 > IgG2 > IgA2, with low levels of IgG3 and IgG4 ASC. Plasma anti-CT antibody responses in all subclasses were seen by day 11 after onset of disease. Although there were no increases in CT-specific ASC of the IgG3 (NS) and IgG4 (NS) subtypes, there were significant increases of these two subclasses in plasma (P ≤ 0.001). The response to CT in the fecal extracts was contributed to by both IgA1 and IgA2 isotypes, with 67 to 75% of the patients responding. Thus, the mucosa-derived ASC and fecal antibodies to LPS and CT were of both the IgA1 and IgA2 subclasses; in plasma, the contribution from IgA2 was lower. Very little difference in the B-cell responses to LPS and CT in the different subclasses was seen in the two groups of cholera patients. Vaccines against O1 and O139 cholera ideally should stimulate antibody subclasses that are likely to offer protection.

Antimicrobial susceptibilities and plasmid contents of Neisseria gonorrhoeae isolates from commercial sex workers in Dhaka, Bangladesh: emergence of high-level resistance to ciprofloxacin.

Abstract: Commercial sex workers (CSWs) serve as the most important reservoir of sexually transmitted diseases (STD), including gonorrhea. Periodic monitoring of the antimicrobial susceptibility profile of Neisseria gonorrhoeae in a high-risk population provides essential clues regarding the rapidly changing pattern of antimicrobial susceptibilities. A study concerning the prevalence of gonococcal infection among CSWs was conducted in Bangladesh. The isolates were examined with regards to their antimicrobial susceptibility to, and the MICs of, penicillin, tetracycline, ciprofloxacin, cefuroxime, ceftriaxone, and spectinomycin by disk diffusion and agar dilution methods. The total plasmid profile of the isolates was also analyzed. Of the 224 CSWs, 94 (42%) were culture positive for N. gonorrhoeae. There was a good correlation between the results of the disk diffusion and agar dilution methods. Some 66% of the isolates were resistant to penicillin, and 34% were moderately susceptible to penicillin. Among the resistant isolates, 23.4% were penicillinase-producing N. gonorrhoeae (PPNG). 60.6% of the isolates were resistant and 38.3% were moderately susceptible to tetracycline, 17.5% were tetracycline-resistant N. gonorrhoeae, 11.7% were resistant and 26.6% had reduced susceptibility to ciprofloxacin, 2.1% were resistant and 11.7% had reduced susceptibility to cefuroxime, and 1% were resistant to ceftriaxone. All PPNG isolates contained a 3.2-MDa African type of plasmid, and a 24.2-MDa conjugative plasmid was present in 34.1% of the isolates. Since quinolones such as ciprofloxacin are recommended as the first line of therapy for gonorrhea, the emergence of significant resistance to ciprofloxacin will limit the usefulness of this drug for treatment of gonorrhea in Bangladesh.

Short-chain fatty acids inhibit fluid and electrolyte loss induced by cholera toxin in proximal colon of rabbit in vivo

Abstract: Short-chain fatty acids (SCFA), acetate,propionate, and butyrate, are produced by bacterialfermentation in the colon and stimulate Na+and Cl- absorption We have studied the effects of SCFAon fluid and electrolyte absorption during cholera toxin(CT)-induced colonic secretion in rabbit, using asteady-state perfusion technique with marker (PEG)dilution Perfusion with SCFA significantly (P <001) reduced colonic water secretion Butyratereduced water secretion the most (95%), followed bypropionate (90%), and acetate (80%) Butyratesignificantly (P < 0001) reduced secretions of Na+(955%), K+ (752%), and Cl- (807%) ions but notHCO3- ions Propionate similarly reduced secretion ofHCO3- (453%) Acetate significantly (P < 0001)inhibited Na+ (764%) and Cl- (757%) secretion, but the inhibitions of K+ (236%) and HCO3- (288%)were not significantly different from the controls Weconclude that SCFA reduce CT-induced water andelectrolyte secretion in the rabbit proximal colon, and its potential as an antidiarrheal agentshould be further evaluated

Association of Vibrio cholerae O1 with the cyanobacterium, Anabaena sp., elucidated by polymerase chain reaction and transmission electron microscopy.

Abstract: It has been hypothesized that Vibrio cholerae is an autochthonous flora of the estuarine and brackish water environment. Zooplankton and phytoplankton have been considered as possible reservoirs. The present study was carried out in microcosms to confirm the role of a cyanobacterium, Anabaena sp., as a reservoir of V. cholerae O1 using culture, polymerase chain reaction (PCR) and immunoelectron microscopy. Survival of culturable V. cholerae in microcosms was monitored by using tellurite taurocholate gelatin agar. Culturable V. cholerae were detected for up to 1 h in association with Anabaena sp. from a microcosm. However, viable but nonculturable (VBNC) V. cholerae O1 were detected for up to 25 months using PCR and immunoelectron microscopy. Results also showed that VBNC V. cholerae can multiply and maintain their progeny in the mucilaginous sheath of Anabaena sp. This is the first time that PCR and immunoelectron microscopy have been used to detect nonculturable V. cholerae in association with Anabaena sp. This study further clarifies the role of Anabaena sp. as a possible reservoir of cholera.

Short-chain Fatty Acids Improve Clinical, Pathologic, and Microbiologic Features of Experimental Shigellosis

Abstract: Because of the metabolic and antibacterial actions of short-chain fatty acids (SCFA), their roles in modifying the clinicopathologic features of shigellosis were evaluated in a rabbit model of shigellosis. Acute colitis was induced in adult rabbits by intracolonic administration of Shigella flexneri 2a. After 24 h, rabbits were given 6-h colonic infusions of SCFA (acetate, propionate, n-butyrate; 60:30:40 mM) or SCFA-free solution (control); groups of rabbits were killed in batches of 2 or 3 animals at 24, 48, 72, and 96 h after treatment, for histologic and bacteriologic assessment. SCFA significantly reduced fecal blood and mucus and improved clinical symptoms. Histologically, SCFA significantly (P<.01) reduced mucosal congestion, cellular infiltration, and necrotic changes. SCFA also significantly (P <.05) reduced the number of shigellae in the colon. No such improvements occurred in the control group. SCFA may be useful agents in improving clinicopathologic features of shigellosis and should be clinically evaluated.

Simultaneous Vitamin A Administration at Routine Immunization Contact Enhances Antibody Response to Diphtheria Vaccine in Infants Younger than Six Months

Abstract: A randomized, double-blind, placebo-controlled trial was conducted to evaluate the effect of simultaneous vitamin A supplementation and diphtheria, pertussis and tetanus (DPT) vaccination on the antibody levels. Infants aged 6-17 wk (n = 56) were randomly given 15 mg oral vitamin A or placebo at the time of their DPT immunization. Three such doses were given at monthly intervals. Immunoglobulin (Ig) G antibodies to diphtheria, pertussis and tetanus were assayed on enrollment and 1 mo after the third dose. Baseline antibody concentrations to diphtheria, pertussis and tetanus did not differ between the vitamin A-supplemented and placebo-treated groups. The postdose antibody to diphtheria level was significantly greater in the vitamin A than in the placebo-treated group. The geometric mean +/- SEM antibody levels (mg/L) were 22.9 +/- 1.2 and 11.0 +/- 1.3 in the vitamin A and placebo groups, respectively (P = 0.029). The postsupplementation concentrations of antibodies to pertussis and tetanus did not differ between the two groups. These results suggest that antibody response to diphtheria vaccination was potentiated by simultaneous vitamin A administration and DPT immunization.

Molecular characterization of a new ribotype of Vibrio cholerae O139 Bengal associated with an outbreak of cholera in Bangladesh.

Abstract: Vibrio cholerae O139 Bengal initially appeared in the southern coastal region of Bangladesh and spread northward, causing explosive epidemics during 1992 and 1993. The resurgence of V. cholerae O139 during 1995 after its transient displacement by a new clone of El Tor vibrios demonstrated rapid changes in the epidemiology of cholera in Bangladesh. A recent outbreak of cholera in two north-central districts of Bangladesh caused by V. cholerae O139 led us to analyze strains collected from the outbreak and compare them with V. cholerae O139 strains isolated from other regions of Bangladesh and neighboring India to investigate their origins. Analysis of restriction fragment length polymorphisms in genes for conserved rRNA (ribotype) revealed that the recently isolated V. cholerae O139 strains belonged to a new ribotype which was distinct from previously described ribotypes of toxigenic V. cholerae O139. All strains carried the genes for toxin-coregulated pili (tcpA and tcpI) and accessory colonization factor (acfB), the regulatory gene toxR, and multiple copies of the lysogenic phage genome encoding cholera toxin (CTXPhi) and belonged to a previously described ctxA genotype. Comparative analysis of the rfb gene cluster by PCR revealed the absence of a large region of the O1-specific rfb operon downstream of the rfaD gene and the presence of an O139-specific genomic region in all O139 strains. Southern hybridization analysis of the O139-specific genomic region also produced identical restriction patterns in strains belonging to the new ribotype and those of previously described ribotypes. These results suggested that the new ribotype of Bengal vibrios possibly originated from an existing strain of V. cholerae O139 by genetic changes in the rRNA operons. In contrast to previously isolated O139 strains which mostly had resistance to trimethoprim, sulfamethoxazole, and streptomycin encoded by a transposon (SXT element), 68.6% of the toxigenic strains analyzed in the present study, including all strains belonging to the new ribotype, were susceptible to these antibiotics. Molecular analysis of the SXT element revealed possible deletion of a 3.6-kb region of the SXT element in strains which were susceptible to the antibiotics. Thus, V. cholerae O139 strains in Bangladesh are also undergoing considerable reassortments in genetic elements encoding antimicrobial resistance.

Intestinal Immune Responses in Patients Infected with Enterotoxigenic Escherichia coli and in Vaccinees

Abstract: Immune responses against enterotoxigenic Escherichia coli (ETEC) were examined in Bangladeshi adults with naturally acquired disease and compared to responses in age-matched Bangladeshi volunteers who had been orally immunized with a vaccine consisting of inactivated ETEC bacteria expressing different colonization factor antigens (CFs) and the B subunit of cholera toxin. B-cell responses in duodenal biopsy samples, feces, intestinal washings, and blood were determined. Because most of the patients included in the study were infected with ETEC expressing CS5, immune responses to this CF were studied most extensively. Vaccinees and patients had comparable B-cell responses against this antigen in the duodenum: the median numbers of antibody-secreting cells (ASC) were 3,300 immunoglobulin A (IgA) ASC/10(7) mononuclear cells (MNC) in the patient group (n = 8) and 1,200 IgA ASC/10(7) MNC in the vaccinees (n = 13) (not a significant difference). Similarly, no statistically significant differences were seen in the levels of duodenal B cells directed against enterotoxin among vaccinees and patients. A comparison of the capacities of the various methods used to assess mucosal immune responses revealed a correlation between numbers of circulating B cells and antibody levels in saponin extracts of duodenal biopsy samples (r = 0.58; n = 13; P = 0.04) after vaccination. However, no correlation was seen between blood IgA ASC and duodenal IgA ASC after two doses of vaccine. Still, a correlation between numbers of CF-specific B cells in blood sampled from patients early during infection and numbers of duodenal B cells collected 1 week later was apparent (r = 0.70; n = 10; P = 0.03).

The lipopolysaccharide of moraxella catarrhalis structural relationships and antigenic properties.

Abstract: Moraxella catarrhalis has recently been shown to be both widespread and pathogenic, in contrast to previous reports. Several factors have been suggested as virulence factors, lipopolysaccharide (LPS) being one. Recent studies have shown the LPS to be without the O-chain, i.e. the polysaccharide part, and to have specific structural features corresponding to each of the three serogroups, A, B and C. The structures resemble in many respects those present in other Gram-negative nonenteric bacteria, with a galabiosyl element as a prominent common denominator. The presence of such common structures suggests that the LPS of these bacteria might be a part of a mechanism of survival for bacteria colonizing the human host.

The distribution of Ascaris lumbricoides in human hosts: a study of 1765 people in Bangladesh.

Abstract: The Ascaris lumbricoides expelled by 1765 people in a poor urban community in Bangladesh were recovered and counted after the subjects had been treated with pyrantel pamoate. The subjects were divided into 22 classes by age and sex (mean n = 80) to examine how prevalence, mean worm burdens and measures of aggregation of worms varied with age and between the sexes, and to see how a measure of aggregation, k, calculated in 3 ways (by maximum likelihood, from moments, or from the percentage uninfected) compared with an empirical aggregation index (the percentage of subjects who expelled an arbitrary 80% of all worms) and with the proportion who were moderately to heavily infected (defined as > or = 15 worms). The prevalence of infection ranged from 64% to 95%, mean worm burdens ranged from 7 to 23 worms, and k ranged from 0.3 to 1.2. There were significant differences between adult males and females in the prevalence of infection, mean worm burdens and measures of aggregation, differences which are probably driven more by behaviour than immunity. The parameter k was better described in terms of the proportion who were moderately to heavily infected (linear; range 0.15-0.58) than by the empirical aggregation index (non-linear; range 0.30-0.49).

Reproductive health needs of adolescents in Bangladesh: a study report.

Abstract: This community-based cross-sectional and descriptive study was conducted in 3 rural and 2 urban areas of Bangladesh using the Operations Research Project surveillance system. The study examines the reproductive health needs of adolescents in Bangladesh. Employing qualitative and quantitative data collection techniques 3961 adolescents aged 10-19 years were interviewed. Findings indicated that about one-fifth of the adolescents did not have any formal education and there was a higher school-dropout rate among urban adolescents. On the other hand girls were mostly married and pregnant on the first year of marriage. Majority of these adolescents were unaware of the sexual changes that occur during puberty and the reproductive process. The study also indicated that 70% of the respondents had heard of family planning practices mostly from television and radio although contraceptive use was low. Knowledge about reproductive diseases was low among rural adolescents and those who have experienced such diseases claim their reluctance to seek treatment for reproductive health. These findings implied that it is imperative to launch effective strategies to make accurate information or services available and accessible to adolescents. Likewise behavior change communication (BCC) is needed to create a supportive environment for adolescents which would necessitate a more comprehensive approach that goes beyond the production of BCC materials to increase community awareness. Finally adolescent-friendly health services should be ensured by arranging special hours or special days orienting and providing training to health care providers on how to counsel adolescents.