Detection of early xerophthalmia by impression cytology and rose Bengal staining--a comparative study

Twenty two cases were studied for early detection of Xerophthalmia by impression cytology and Rose Bengal staining. Patients were below 6 years of age and admitted in the paediatric ward of Dhaka Medical College Hospital. Assessment were done by conjunctival impression cytology and staining with 1% Rose Bengal dye. Estimation of serum retinol level was done by HPLC to correlate conjunctival findings with biochemical status. The mean age of the subjects were 3.15 +/- 1.75. Rose Bengal staining was positive in 40% cases and impression cytology was in 60% cases. The mean serum retinol level of the diseased children were 10.5 +/- 3. ug/dl. The sensitivity of Rose Bengal staining was 53.3% and that of impression cytology was 80% in detecting vitamin A deficiency when compared with serum retinol level. The specificity of Rose Bengal staining was 40% and that of impression cytology was 100%. Sensitivity of impression cytology was 100% in patient with retinol level 10 ug/dl.

Seroepidemiologic evaluation of antibodies to rotavirus as correlates of the risk of clinically significant rotavirus diarrhea in rural Bangladesh

A case-control study was conducted among children and adult women in rural Bangladesh to evaluate whether serologic immunity to rotavirus was associated with a lower risk of rotavirus diarrhea of sufficient severity to cause patients to seek medical care. Acute-phase sera from 219 cases of rotavirus diarrhea, detected among patients treated in three diarrheal treatment centers, were compared with sera from 477 contemporaneously selected community controls. Overall, serum IgG antirotavirus antibody titers were nearly one-fourth as high in cases as in controls (107 vs. 417 units/ml; P less than .001). Among persons aged greater than or equal to 8 months, in whom titers of maternal antirotavirus antibodies should have been negligible, even the lowest range of detectable titers (100-200 units/ml) was associated with a substantial (75%, P less than .05) reduction of the risk of rotavirus diarrhea. We conclude that titers of serum IgG antirotavirus antibodies induced by earlier infection were inversely related to the risk of clinically significant rotavirus diarrhea.

Antibody responses after immunization with killed oral cholera vaccines during the 1985 vaccine field trial in Bangladesh

Sera collected during the 1985 oral cholera vaccine trial in Matlab, Bangladesh, which demonstrated efficacy of a whole cell combined with cholera B subunit vaccine (WC/BS) and a whole cell only vaccine (WC), were analyzed for antitoxin and vibriocidal antibodies. Before vaccines were given, antitoxin titers were highest in children, especially those with O blood group, whereas vibriocidal titers rose throughout life. Two weeks after three doses of vaccine, geometric mean antitoxin titers were 2.5-4.5 times higher in vaccinees who received the WC/BS vaccine; the vibriocidal titers were 1.3-2.1 times higher in vaccinees who received either vaccine. The titer elevations were relatively brief and were barely detectable 7 months after the third dose even though significant levels of protection persisted greater than or equal to 3 years. Thus, the oral vaccines induced a serum response in this large field trial that was similar to that seen in earlier pilot studies, but the duration of the serum responses was much shorter than the duration of the protection.

Field trial of oral cholera vaccines in Bangladesh: serum vibriocidal and antitoxic antibodies as markers of the risk of cholera

The relationship of serum vibriocidal (VC) and IgG anti-cholera toxin (CT) antibodies to the risk of cholera was evaluated during the first year of follow-up of recipients of three oral doses of B subunit (BS)-whole-cell vaccine, whole-cell vaccine, or Escherichia coli K12 strain placebo in Bangladesh. Acute sera from 121 cholera patients were compared with sera from 2592 contemporaneous community controls. Each doubling of VC titer was associated, on average, with a 22%-47% reduction of cholera risk in the three groups. In contrast, in the two groups that did not receive BS, anti-CT titers were directly associated with cholera and thus served as markers of higher cholera risk. Each vaccine conferred approximately 65% protective efficacy against cholera, but antibody titers did not correlate with vaccine efficacy, indicating that serum VC and anti-CT antibodies are poor markers of the longitudinal pattern of vaccine efficacy.

Field trial of oral cholera vaccines in Bangladesh: evaluation of anti-bacterial and anti-toxic breast-milk immunity in response to ingestion of the vaccines

In a field trial conducted in Bangladesh, ingestion of either B subunit-killed whole cell (BS-WC) or killed whole cell (WC) oral cholera vaccines by mothers was associated with a 47% reduction of the risk of cholera in their non-vaccinated children aged under 36 months. Because vaccine-induced breast-milk immunity seemed a possible explanation for these findings, we evaluated anti-lipopolysaccharide (LPS) and anti-cholera toxin (CT) IgA antibody responses in breast milk collected during the trial from 53 lactating women who ingested three doses of BS-WC, WC, or an Escherichia coli K12 strain (K12). Despite induction of moderate vibriocidal (1.4 to 2.0-fold) and anti-CT (4.5-fold) serum antibody responses, the vaccines did not elicit significant rises of anti-LPS or anti-CT IgA breast-milk antibodies. The failure of the vaccines to elicit significant levels of breast-milk anti-cholera antibodies suggests an alternative explanation for protection of young children by maternal vaccination, such as interruption of maternal-child transmission of Vibrio cholerae 01.

Seroepidemiologic evaluation of anti-toxic and anti-colonization factor immunity against infections by LT-producing Escherichia coli in rural Bangladesh

To evaluate serologic immunity against clinical infections by heat-labile enterotoxin-producing Escherichia coli (LT-ETEC) in rural Bangladesh, 124 children and adult women with LT-ETEC diarrhea (cases) were compared with 347 age-matched community controls. In paired acute-convalescent sera from the cases, IgG anti-CFA I and anti-CFA II antibody titers increased eight-to ninefold after infection by LT-ETEC with the homologous CFA, and IgG anti-LT antibody titers increased fourfold for all LT-ETEC infections. Anti-CFA and anti-LT titers peaked in controls aged 12-23 months, the age group with the highest incidence of ETEC infections. However, antibody titers were similar in acute sera from cases and in sera from controls. Although serum IgG anti-CFA and anti-LT antibodies rose in response to LT-ETEC infections and paralleled the age-specific incidence of ETEC in the community, these antibodies were not associated with a lower risk of LT-ETEC diarrhea.

Effects of undernutrition on infection with Vibrio cholerae O1 and on response to oral cholera vaccine

The association between undernutrition and the risk of colonization and disease with Vibrio cholerae O1, concentrations of salivary IgA and the serologic response to infection and to orally administered cholera B subunit were examined prospectively in a family study in Bangladesh. Children ages 1 to 8 years who were family contacts of patients hospitalized with culture-confirmed cholera were visited within 24 hours of the hospitalization and daily for 10 days, queried for the presence of diarrhea and cultured for V. cholerae O1. On Day 1 each child was weighed and saliva was collected to measure total IgA. On Days 1 and 21 blood was taken to assess vibriocidal and antitoxin titers, and on Days 1 and 2 B subunit or placebo was given orally as part of a trial to look for a toxin-blocking effect. Of 412 children enrolled in the study 35% (143) became infected with V. cholerae O1 and 49% (70) of these developed diarrhea. Undernutrition, defined in a child as weight less than 70% of the Harvard reference weight-for-age, was not associated with colonization, disease or the duration or severity of cholera. Moreover well-nourished children did not differ from undernourished children in their concentrations of salivary total IgA, initial serum antitoxin or vibriocidal antibodies or in their serologic response to colonization, disease or B subunit. The immune system in its response to cholera appears to be quite resistant to nutritional insults. The good antitoxin response to B subunit among undernourished children is of particular importance in considering the use of future oral cholera vaccines in areas where such undernutrition is common.

Maximum likelihood estimation of components of variance and correlations in the analysis of family data

A simple iterative method is developed for computing the maximum likelihood estimates of the components of variance and thereby the intraclass and interclass correlations, under multivariate normal assumptions involving two classes. The method works efficiently for both balanced and unbalanced data and can be readily extended to situations involving three or more classes. It is particularly suitable for application to studies of quantitative variables in genetics and is illustrated by using some dermatoglyphic data.

B subunit-whole cell and whole cell-only oral vaccines against cholera: studies on reactogenicity and immunogenicity

We conducted a randomized trial among persons in rural Bangladesh to evaluate the side effects and immunogenicity of orally administered B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) cholera vaccines and a killed Escherichia coli strain K12 placebo proposed for field testing. Three doses of BS-WC, WC, E. coli, or a control agent were given with antacid to 1,257 women (aged greater than 15 years) and children (aged to to 15 years). The four groups exhibited no statistically significant differences in occurrence of symptoms after each dose, and rises in titers of vibriocidal (VC) antibodies to Inaba and Ogawa were twofold higher for vaccinees than for controls (P less than .001). Half of the persons with fourfold or greater VC responses to WC responded after the first dose; many additional patients, particularly young children, responded after subsequent doses. In contrast, 89% of persons who responded to BS-WC with twofold or greater rises in titer of IgG antibodies to cholera toxin did so after the first dose. After the third dose, vaccinees exhibited a fivefold higher rise in titer than did controls (P less than .001); a dose-to-dose booster effect was most evident in young children.

Local and systemic antibody responses to naturally acquired enterotoxigenic Escherichia coli diarrhea in an endemic area

Fifteen patients hospitalized with acute, watery diarrhea and with enterotoxigenic Escherichia coli (ETEC) detected from stool samples were studied to evaluate the extent to which natural ETEC diarrhea induces local and systemic antibody responses to E. coli heat-labile toxin (LT), homologous lipopolysaccharide (LPS), and colonization factors (CFA/I and CFA/II). Specific IgA and IgG antibodies to LT, CFA I and II, and each patient's homologous LPS were determined by ELISA in serum, saliva, breastmilk, and intestinal lavage fluid. The majority of patients had greater than a twofold rise in local levels of IgA antibodies in the intestine: 80% of LT+ patients responded to LT, 63% of CFA+ patients responded to CFA, and 78% of all toxin-positive patients responded to the LPS of their infecting strain. Local antibody responses in the intestine were associated with responses in breastmilk and saliva, but relationships were not clear-cut, and the usefulness of these secretions as proxy measures of local intestinal antibody production remains unclear. Antibody responses in serum also occurred in most patients and were significantly more frequent in cases than in controls. This study demonstrates that natural ETEC disease results in local IgA responses to LT, CFA, and LPS in the gut and also in immune responses in breastmilk, saliva, and serum.

Seroepidemiological studies of El Tor cholera in Bangladesh: association of serum antibody levels with protection

In rural Bangladesh, family contacts of patients with cholera were studied prospectively to examine whether protection against colonization and disease due to Vibrio cholerae O1 was associated with circulating antibodies to V. cholerae. Family contacts (1,071) of 370 patients with cholera were visited daily for 10 days, cultured for V. cholerae, and queried about diarrhea. Sera collected on days 1 and 21 were assayed for vibriocidal antibodies, IgG and IgA antibodies to cholera toxin, and IgG antibodies to lipopolysaccharide (LPS). Vibriocidal titers of greater than or equal to 20 present in 50% of contacts by 20 years of age were associated with protection against both colonization and disease. An elevated level of IgG antitoxin was not associated with protection against colonization or disease but was the most sensitive indicator of recent symptomatic cholera and of immune response to the oral immunogen B subunit. IgG antibody to LPS and IgA antitoxin were of little value in predicting colonization or disease.

Microtiter ganglioside enzyme-linked immunosorbent assay for vibrio and Escherichia coli heat-labile enterotoxins and antitoxin

We have developed a microtiter enzyme-linked immunosorbent assay method for detecting the heat-labile enterotoxins of Vibrio cholerae and Escherichia coli using GM1 ganglioside as the base coat. This method compares favorably with a similar assay using anticholera toxin as the base coat, and with the Y1 adrenal cell assay. The assay should be useful in detecting enterotoxin production in E. coli and vibrios (including non-agglutinating Vibrio), in quantitating the toxin, and in determining binding properties of enterotoxins to ganglioside. The assay can also be used to quantitate antibodies which block the attachment of the toxin to the ganglioside.

The photosensitivity of the malate oxidase system of a pigmented strain and a carotenoidless mutant of Sarcina lutea (Micrococcus luteus)

The effect of white light on the malate oxidase of Sarcina lutea (Micrococcus luteus) membranes has been examined using a carotenoid-containing and a carotenoidless mutant. At least three photosensitive sites have been detected. Two of these are associated with the malate dehydrogenase complex (malate-menaquinone reductase) and are unaffected by membrane carotenoid. A third site which has been detected beyond the dehydrogenase complex, is protected by carotenoid since it can only be demonstrated in carotenoidless systems. A repair mechanism has been found for one of the two sites in the dehydrogenase complex.