Comparison of the protective efficacy on mekongi schistosomiasis in mice induced by antigens derived from cercariae, schistosomulae and adult worms.

Protective efficacy of the extracts of cercariae, schistosomulae and adult worms of S. mekongi was studied in mice receiving immunizations with these extracts emulsified with Freund's complete adjuvant initially and incomplete adjuvant subsequently, and compared with mice receiving physiological saline with or without adjuvants as controls. After challenge with cercariae, the animals were sacrificed and the larvae or adult worms harvested by lung recovery and perfusion techniques on day 5 and weeks 6-8, respectively. Worm reduction rates were significantly higher in mice receiving extracts of schistosomula (59%) and adult worms (51%) than in those receiving the cercarial extracts (31%). Similar findings were obtained with the perfusion technique showing worm reduction rates of 57%, 53% and 30% in mice receiving extracts of schistosomulae, adult worms and cercariae, respectively. ELISA antibody titers were correspondingly increased in mice receiving extracts of schistosomulae and adult worms, but not in those receiving cercariae. This apparent association may be inadequate to suggest that the increase in ELISA titer be used as an indicator for resistance in mekongi schistosomiasis.

Behavior of people with respect to malaria in endemic areas with different levels of malaria transmission.

The present survey was carried out in two villages of the same malaria endemicity but different levels of transmission in Lamae District, Chumphon Province, southern Thailand with the aim to study whether behavior of people to malaria was similar or not. The total populations in low (village 11) and high (village 13) transmission areas were surveyed twice during low (February 1990) and high (June 1990) transmission periods. All subjects were interviewed by trained interviewers using a structured interview form. Among 410 and 614 people in villages 11 and 13, respectively, it was revealed that during the low transmission period behavior related to chemoprophylaxis and use of bed nets was similar in both villages, whereas risk behavior of night work was significantly higher in village 11 than village 13. This was likely due to their different principal occupations: farming of rubber plantation in village 11 and of coffee plantation in village 13. Concerning pattern of seeking malaria treatment, the malaria clinic and the district hospital were the common places attended by people in both villages. During the second survey in high transmission period, a cohort of 277 in village 11 and 430 in village 13 were available for follow up to study changes in their behavior between low and high transmission seasons. There were significant decrements related to night work and significant increments related to bed net use in both villages.

Assessment of the effectiveness of oral rehydration therapy against severe diarrheal dehydration.

A hospital based case-control study for assessing the effectiveness of oral rehydration therapy (ORT) preparation against severe dehydration due to diarrhea was conducted at the Infectious Diseases Hospital, Jakarta, Indonesia. A total of 202 children aged 24 months or less who attending the hospital were suffering from acute watery diarrhea were recruited in the study. Those who were severely dehydrated as assessed by WHO criteria were accounted as cases; those who were non-severely dehydrated were accounted as controls. There were 59 cases and 143 controls. A questionnaire was used to interview all study subjects' mothers about ORT usage and various risk factors. Mothers who used ORT were asked to show how they prepared either oral rehydration solution (ORS) or sugar salt solution (SSS). Effectiveness of ORT against severe diarrheal dehydration was based on the formula for assessment of vaccine efficacy by using the odds ratio (OR). With the use of the logistic regression method, an adjusted OR was obtained after controlling various confounders. The effectiveness of ORT against severe diarrheal dehydration was 72.1% for proper ORT preparation and was decreased to 63.2% when ORT was improperly prepared.

Assessment of sanitation conditions by qualitative sanitation measurement.

Survey of sanitation conditions by qualitative sanitation measurement were carried out in three districts, Chachoengsao Province, Thailand. The sanitation of each household was assessed in terms of positive stool examination and scores of seven main sanitary activities which were used to classify each household's sanitation as hygienic or non-hygienic. Stool collections were made from each household's housewife and examined for pathogenic bacteria and parasites. It was found that in the qualitative measurement of the household's sanitation as hygienic or non-hygienic, most sanitary activities were highly associated with the results of stool examination. From consideration of the sensitivity, specificity and kappa coefficient of significant sanitary activities as predictors and the result of stool examination was used as gold standard, it was apparent that a package of all main sanitary activities was the most appropriate measurement in the survey to assess sanitation conditions in the community.

Effect of low birth weight on severe childhood diarrhea.

A hospital-based case-control study was conducted at Phanat Nikhom District Hospital, Chon Buri Province, Thailand to determine the association between low birth weight and severe diarrhea and its magnitude of association among children under two years of age. Data were analyzed from 52 severe diarrheal cases and 121 mild diarrheal children attending the hospital during October 1988 to December 1989. Information regarding birth weight was obtained from hospital record or health care of each subject. Information on variables which may confound the association between low birth weight and severe diarrhea were also collected by interviewing all subjects' mothers with structured questionnaires. It was found that the crude Odds Ratio between low birth weight and severe diarrhea was 4.62. However after controlling for confounding variables: age, concurrent infection, duration of diarrheal attack prior attending hospital and ORT usage, the adjusted Odds Ratio was 3.92. The present study confirms that low birth weight is an important determinant of severe diarrhea and feasible intervention in the case of low birth weight needs to be explored.

Knowledge of diarrhea and socioeconomic factors in relation to the use of oral rehydration therapy in Samut Songkhram Province, Thailand.

A study to determine the association between the use of oral rehydration therapy (ORT) by mothers who had children under five years old with diarrhea and their knowledge of diarrhea was conducted in 19 health centers and a hospital at Muang District, Samut Songkhram Province. It was found that in general there was significant association between the use of ORT and mother's knowledge of diarrhea. This significant association was still evident after considering socioeconomic factors such as age, occupation, education and economic status. It was also noted that mothers with high knowledge of diarrhea gave ORT to their children under five with diarrhea two times more frequently than mothers with low knowledge of diarrhea. The present study confirms the impact of knowledge of diarrhea on the use of ORT.