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Electron acceleration by a laser pulse having a Gaussian radial and temporal profile of intensity has been studied. The interaction region is vacuum followed by a gas. The starting point of the gas region has been chosen around the point at which the peak of the pulse interacts with the electron. The tunnel ionization of the gas causes a defocusing of the laser pulse and the electron experiences the action of a ponderomotive deceleration at the trailing part of the pulse with a lower intensity rather than an acceleration at the rising part of the laser pulse with a high intensity, and thus gains net energy. The initial density of the neutral gas atoms should be high enough to properly defocus the pulse; otherwise the electron experiences some deceleration during the trailing part of the pulse and the net energy gain is reduced. The rate of tunnel ionization increases with the increase in the laser intensity and the initial density of neutral gas atoms, and with the decreases in the laser spot size, which causes more defocusing of the laser pulse. The required initial density of neutral gas atoms decreases with the increase in the laser intensity and also with the decrease in the laser spot size.

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An outbreak of acute diarrhoeal disease occurred in Dhalai and North Tripura district, Tripura during month of May 2004. An investigation was done to identify causative agent with anti microbial susceptibility pattern and to know the epidemiological feature. Overall attack rate and Case Fatality Rate (CFR) was 18.8%. and 6.9/1000 respectively. Vibrio cholerae O1 biotype El Tor, Ogawa was isolated as sole pathogen in 40% of hospitalized acute diarrhoea patient and from a water samples examined. The strains were sensitive to Tetracycline, Doxycycline, Norfloxacin, Ciprofloxacin, Chloramphenicol, and Azithromycin. Bad peridomestic sanitation, use of contaminated surface water along with low literacy, lack of personal hygiene, frequent movement might be the factor associated with persistence and spread of pathogen amongst tribal groups leading to outbreak of cholera.

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AIM: To determine the role of zinc supplementation in reducing diarrhoeal morbidity in children. METHODS: A randomized, double-blind, community-based intervention study was conducted in 280 rural children aged between 6 and 41 mo. Children were randomly allocated into three groups. One group received a daily dose of 10 mg zinc for 5 d wk(-1), another group received 50 mg zinc once weekly and the remaining group received placebo. Zinc was supplemented for 16 wk from November 1999. Diarrhoeal episodes were detected by weekly surveillance during the supplementation period. RESULTS: Eighty diarrhoeal episodes were detected among 59 children in all 3 groups. The groups were compared with each other at baseline and as regard to the outcome variable (incidence of diarrhoea). The proportion of children suffering from diarrhoea during the period was significantly lower in the zinc-supplemented groups (15.8% in daily and 16.5% in weekly group) than in the placebo group (30.8%). The incidence of diarrhoea in the daily and weekly zinc-supplemented groups was 0.68 and 0.69 episodes child(-1) y(-1), and that in the placebo group was 1.67 episodes child(-1) y(-1) (relative risk 0.41, 95% confidence interval 0.24-0.71). Diarrhoeal incidence of < 4 d duration was found to occur significantly less often in the supplemented groups. There was no difference in diarrhoeal incidence between the daily and weekly zinc-supplemented children. There were no detected adverse reactions in any of the supplemented groups. CONCLUSION: The study indicates that zinc supplementation is effective in reducing diarrhoeal morbidity when administered either daily or in a weekly schedule.

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BACKGROUND & OBJECTIVES: An explosive outbreak of diarrhoeal disease which occurred in the Baishnabghata, Patuli area of Kolkata Municipal Corporation during September 28 to October 12, 2000, was investigated by a team from the National Institute of Cholera and Enteric Diseases, Kolkata, to identify the causative agent and determine the antimicrobial susceptibility pattern. METHODS: Clinical and epidemiological data were collected from domiciliary cases and also from patients attending two medical camps that had been set up for the purpose. Stool and water samples were collected for isolation of diarrhoeagenic pathogens. RESULTS: A total of 710 cases of diarrhoea occurred with an attack rate of 7.1 per cent; majority were adults. All 6 faecal samples and 2 water samples collected, were positive for Vibrio cholerae O139. The strains were uniformly (100%) susceptible to the commonly used drugs for cholera such as tetracycline, norfloxacin, ciprofloxacin, co-trimoxazole and nalidixic acid but resistant (100%) to furazolidone and ampicillin. INTERPRETATION & CONCLUSION: This is the first localised outbreak of V. cholerae O139 in Kolkata since the devastating epidemic in 1992. Extensive chlorination of all water sources resulted in a dramatic decline of the outbreak. The appearance of resistance in V. cholerae O139 to furazolidone is a matter of great concern since this drug is used for the treatment of cholera in children and pregnant women.

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BACKGROUND AND OBJECTIVES: a number of studies have shown the association between vitamin A deficiency and the increased risk of diarrhoeal and other childhood morbidities and mortality. However, some studies have raised controversies regarding the reduction of the incidence of diarrhoea after vitamin A supplementation to children. This study was undertaken to evaluate the effectiveness of vitamin A supplementation to young rural children in reducing the incidence of diarrhoea. METHODS: a double-blind randomized intervention trial was carried out amongst 404 rural children between 6-59 months of age to assess the impact of vitamin A supplementation on morbidity due to diarrhoea. Children aged 6-59 months were enrolled and allocated to receive either 200,000 or 50,000 IU of vitamin A and the same dose was repeated after six months. Morbidity due to diarrhoea was observed by twice-a-week household surveillance, during the subsequent one year of follow up. The incidence of diarrhoea was compared between the two supplemented groups. In addition, the overall incidence of diarrhoea n the two supplemented groups was also compared with the incidence observed during the year preceding supplementation. RESULTS: the incidence of diarrhoea was similar in the two supplemented groups (Incidence Rate Ratio = 1.05. 95% C. I. 0.79-1.40). However, the overall incidence of diarrhoea among all the children in the two supplemented groups (0.56 episodes/child/year) was significantly lower than the incidence before supplementation (1.15 episodes/child/year). The Incidence Rate Ratio was 0.49 with 95% C.I 0.40-0.59. INTERPRETATION AND CONCLUSIONS: the results of this study indicate that vitamin A supplementation in a dose of 200,000 IU, has no additional advantage over 50,000 IU, at least when the aim is to reduce the incidence of diarrhoea. For control of morbidity due to diarrhoea, vitamin A supplementation in a dose of 50,000 IU every six months appears to be adequate, cost effective and suitable for younger children.

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An outbreak of cholera occurred in Maldah district, West Bengal during July-August 1998. Attack rate was 34/1000. Cases were more (59.3%) amongst adults (> 15 years.). V. cholerae 01 biotype E1 Tor serotype ogawa was isolated as a single pathogen from 52.9% (9/17 samples examined). All V. cholerae strains belonged to phage type 2 (Basu and Mukherjee scheme) and type 27 (new phage type scheme). The strains were resistant to co-trimoxazole, furazolidone, ampicillin, streptomycin and nalidixic acid.

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Knowledge of rural mothers related to five diarrhoeagenic risk behaviours, identified in an earlier study, was ascertained. A high proportion of mothers (67%-79%) had knowledge about risk of bottle feeding, non-use of soap for cleaning feeding containers, storage of drinking water in wide-mouthed vessels and indiscriminate disposal of children's faeces. However, only around 31% of mothers were aware about danger of using pond water for cleaning feeding containers. Risk behavioural practices were less amongst mothers who had knowledge about them. Risk of diarrhoea amongst children of mothers having risk practice without knowledge as compared to those who utilised their knowledge to avoid risk practice was found significantly higher (p < or = 0.005) except for bottle feeding (p = 0.330). The results of this study indicate that children can be protected significantly from diarrhoea if mothers' diarrhoeagenic behaviours can be altered through educational intervention.

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Maternal behaviours related to certain child care practices which possibly have a contributory role in causation of diarrhoea in children were studied. Comparison was made between behaviours of mothers in 108 families having diarrhoeal children (Case families) with mothers of 72 families having age and neighbourhood matched non diarrhoeal children (control families) using a logistic regression model. Five risk behaviours were identified and these are bottle feeding (OR-2.87; CI-1.30 to 6.34), non-use of soap for cleaning feeding container (OR-2.61; CI-1.30 to 5.23), water storage in wide-mouthed container (OR-2.75; CI-1.27 to 5.96), use of pond water for the same (OR-2.36; CI-1.15 to 4.84) and indiscriminate disposal of children's stool (OR-1.99; CI-0.97 to 4.08). Around 83 per cent of diarrhoeal families could be predicted using these five variables only. The first three of these five risk behaviours were responsible for occurrence of significantly higher incidence (3 or more episodes) of diarrhoea in the case families. All these risk behaviours are amenable to change if suitable intervention is initiated. The result of this study would be helpful in reducing diarrhoea associated morbidity to a substantial level.

PIP: A number of studies have documented the existence of a relationship between certain behavioral practices at the family level and an increased incidence of diarrhea among children. Findings are reported from a study in which mothers' behaviors in diarrheal and control families were compared to selected child care practices which may help cause diarrhea in children. The authors compared the behaviors of mothers in 108 families having children with diarrhea (case families) with mothers of 72 families having age and neighborhood matched nondiarrheal children (control children) using a logistic regression model. The following risk behaviors were observed: bottle feeding, non-use of soap for cleaning feeding containers, water storage in wide-mouthed containers, the use of pond water for the same, and the indiscriminate disposal of children's feces. 81.5% of diarrheal families could be predicted using only these 5 variables. The most significant risk behavioral practices of mothers were bottle feeding, non-use of soap for cleaning feeding containers, and drinking water storage in wide-mouthed containers. All of these risk behaviors are subject to change if exposed to the appropriate interventions.

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The present study was undertaken to gain insight into the sources of faecal contamination of infants in rural Bengal. It was carried out in three villages near Calcutta, India, from June 1993 to August 1995 among 148 infants and their mothers. Escherichia coli was used as an indicator of faecal pollution. A total of 725 samples, including hand rinsings of children and mothers, feeding utensils and leftover food were examined. The total isolation rate of faecal E. coli was 30%. The isolation rates from hands of children and mothers were 17% and 40% respectively. The germs from 30% of utensils and 59% of leftover food and drinks were recovered further. The study highlights the precarious hygiene in rural Bengal.

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Importance of faecal leucocyte count as an indicator of invasiveness in mucoid diarrhoea was studied. A total of 290 faecal specimen, 170 from mucoid diarrhoea and 120 from watery diarrhoea were examined for faecal leucocyte count under high power field (hpf) from rural children below four years of age during the period from November 1992 to October 1995. Faecal leucocyte count > 10/hpf was noted in 45.9% of mucoid diarrhoea as against 19.2% of watery diarrhoea (p < 0.0001) samples. From faecal samples with > 10 faecal leucocyte count, invasive pathogens could be recovered in 19 (24.5%) to none of 23 patients with watery diarrhoea (p < 0.006 Fisher exact test). This sample test appears to be of value as an indicator of invasiveness in mucoid diarrhoea in the absence of culture facility.

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In a rural community-based prospective study, diarrhoea in relation to the feeding patterns of a cohort of infants was studied. A total of 148 infants between the ages of 0 and 2 months were enrolled and followed until the completion of 1 year of age. Survival analysis showed that by the fourth month of age exclusive breastfeeding dropped by 75%. The proportion of complementary breastfeeding increased from 18.6 to 52.9% during the same period and to 83.7% by the eighth month. This study clearly highlights the tendency for early switch over from exclusive breastfeeding to complementary breastfeeding. Early weaning was associated with an incidence rate ratio (IRR) of 3.02 (95% CI 1.043-8.802). The IRR of 3.02 and its confidence limits (1.043-8.02) suggest a significant protective effect of exclusive breastfeeding against diarrhoea in infants. The results of this study indicate that promotion of exclusive breastfeeding has a potential role to reduce the incidence of diarrhoea amongst infants. The findings of this study will be useful for Diarrhoeal Disease Control Programme in reducing diarrhoeal morbidity.

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A study was carried out in 3 villages near Calcutta, India, having a population of 5464, between August 1992 and December 1994. A cohort of rural children below 4 years of age was prospectively observed to determine the clinico-epidemiological aspects of mucoid diarrhoea and examine propensity to invasiveness. Overall, the incidence of diarrhoea was 1.7 episodes/child/year, and that of mucoid and bloody dysentery was 0.8 and 0.2 episodes/child/year, respectively. Children aged 6-11 months had a higher incidence of mucoid diarrhoea (1.3 episodes/child/year) and the peak season occurred in June and July. Multivariate analysis using logistic regression showed that mucoid diarrhoea and bloody dysentery were closely similar in both clinical and laboratory findings, including raised faecal leucocyte count (> 10/high power microscope field [hpf]). However, abdominal pain occurred more frequently in bloody dysentery than in mucoid diarrhoea. Faecal leucocyte count (> 10/hpf) can therefore be used as an indicator for invasiveness of mucoid diarrhoea at the community level.

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A study was undertaken to assess the parasitic infection rate in a rural community of West Bengal amongst children below four years of age suffering from gastrointestinal complaints. A total of 221 faecal samples were examined during November 1992 to April 1994. G. lamblia (17.2%) and E. histolytica (8.1%) were the predominant protozoas, whereas E. vermicularis (12.2%) and A. lumbricoides (8.1%) were found to be common amongst helminthic infection. A significantly lower infection rate was observed in children below one year (24.4 per cent) as compared to older age groups (66.4 per cent).

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A total of 27 families of hospitalised patients (index case families) suffering from acute watery diarrhoea caused by Vibrio cholerae O139, and 14 neighbourhood families were bacteriologically screened for 4 consecutive days to determine the extent of V. cholerae O139 infection amongst healthy contacts and other suspected vehicles of transmission at the intrafamilial level. V. cholerae O139 was isolated from faeces of 14.6% of healthy contacts in index case families as compared to none in neighbourhood families (P = 0.002). The organism could be recovered from 3.7% of handwashings of contacts of index cases and also from stored drinking water (8.0%), open well water (28.6%), flies (3.8%) and pond water (25.0%) used by the index case families and none from neighbourhood families. The large number of asymptomatic infected persons indicate an epidemiological similarity to that of eltor cholera. The organisms may be carried on hands and may act as a potential source of infection to other inmates through contamination of stored drinking water, open wells etc. The results will be useful in formulating strategies for intervention of transmission of V. cholerae O139 at the community level.

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The review of the current status and implementation of Oral Rehydration Therapy at the community level have been presented in this communication with special emphasis on its development, ORS access rate, ORS use rate and home available fluids. The global ORS supply has gone up an increased eleven folds since 1981. Similarly the ORS access rate has also increase from 46% to 68% in 1991. However, the global ORS use rate was low (21%). The major constraints during ORT implementation which have been reported by several scientists are also discussed.

PIP: Dehydration is the major reason children die from diarrhea. The key element of the WHO Diarrhoeal Disease Control (CDD) Programme is implementation of oral rehydration therapy (ORT). ORT implementation includes production and distribution of packets of oral rehydration salts (ORS), training of medical and paramedical personnel and education of mothers, and operational/health services research for identification of suitable strategies for implementation. Most ORT-related research has been done in hospitals. Community health workers in India have been given ORS packets to use to treat diarrhea cases at home. Operational research in India shows that volunteer health guides can train mothers to give available and culturally acceptable home fluids to children with mild diarrhea before dehydration develops. Use of home available fluids greatly reduces the need for ORS packets. Another possible alternative to ORS was sugar salt solution (SSS) or household formula, but research shows that mothers tend to prepare SSS inaccurately. The success of the CDD program depends on ORS production and proper distribution. In India, more than 100 companies produce about 130 different commercial ORS products, indicating a need for quality control. The best indicators to evaluate India's CDD program are ORS access and ORT use rates. In India, the 1991 ORS and ORT use rates were only 7% and 14%, respectively. The approach to ORT in India is mothers should treat children with diarrhea with no dehydration, village level workers should manage dehydrated patients with ORS, and health professionals at the nearest health facility should treat severely dehydrated patients with either ORS or intravenous fluids. ORT has reduced child mortality in India from 1.9% to 0.6%. Major barriers to ORT implementation are scarcity of resources, lack of political commitment, managerial and organizational problems, and problems related to community participation, health personnel, and dissemination of information.

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During an operational research study on implementation of oral rehydration therapy in a block of West Bengal, India, amongst a population of 2, 16,805, a total of 171 Community Health Guides and 152 Anganwadi Workers were initially trained for one working day by lectures and slides about diarrhoea case management at the community level. The training was evaluated after two months and found to be inadequate. The workers were then retrained with modern approach using a module (prepared in local language) as suggested by World Health Organisation. The level of retention of the imparted knowledge of Health Workers for different items 2-3 months after training with lectures and slides ranged between 5-25% except preparation of ORS which was 80%. With the use of modules, 47-98% of health workers could retain the same knowledge 3 months after the training. The knowledge thus acquired were sustained even after 12 months of training to a level which was still much better than that retained 2 months after training with slides and lectures. However some of the items like indication of use of Home Available Fluids, dosage of ORS and when to refer a diarrhoea case to health facility were more difficult to recall after one year. This possibly indicates need for in-service training of grassroot level health workers at suiTable interval.

PIP: In India, the National Institute of Cholera and Enteric Diseases implemented an operations research project on oral rehydration therapy in the rural block of Polba of Hooghly district in West Bengal. Its physicians used lectures and slides to train grassroot level health workers about dehydration signs, management of diarrhea, referral of patients with diarrhea to the Primary Health Center, and how to educate mothers in the community about early management of diarrhea. Each health worker received a reference booklet, prepackaged oral rehydration salts (ORS), and a 1-liter standard plastic container. Two months after the initial training, their knowledge was reevaluated and they underwent retraining. A module in Bengali was used for the retraining. It consisted of individual readings, examples and exercises of simulated conditions, discussions, role playing, and demonstration of ORS preparation. The workers were reevaluated at 3 months and 1 year post-retraining. Other than preparation of ORS (80%), few grassroot workers retained the messages delivered via the lecture and slides approach (5-25%). For example, only 5% could correctly identify the signs of dehydration. On the other hand, many more health workers retained the messages delivered via the modular approach 3 months after retraining (47-98%). At 12 months post-retraining, dosage of ORS, referral, and use of home fluids were more difficult to recall than were signs of dehydration, indication of ORS, and preparation of ORS (18-29% vs. 48-87%). These results show that periodic refresher training increases knowledge to a sustained level. The researchers concluded that simple booklets in local scripts facilitate efficient training of health workers in diarrheal treatment services. Each worker should have his/her own personal copy.

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In a cross sectional study of total 14514 tribal Nicobarese people of Car Nicobar Island, an union territory of India, situated in Bay of Bengal, morbidity, mortality and treatment practices of diarrhoeal diseases of under-five children were surveyed. The incidence of diarrhoea (0.2 episode/ch.year), Crude death rate (3.6/1000) and IMR (31/1000 live births) were exceedingly low as compared to SouthEast Asian Countries including mainland of India. ORS utilisation rate was high (41%) as compared to the National figure (12.0%). This is the first study of it's kind carried out in this island and amongst the Nicobarese tribe in India. A preliminary study carried out among the mothers of the hospitalised children indicated that protective behaviours like breast feeding, hand washing, use of chlorinated water and proper disposal of stool were regularly being practiced by the community traditionally. An in-depth study on risk factors of diarrhoea in this island can yield useful clue for describing the same.

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An operational study of a 3-tier strategy for implementation of oral rehydration therapy (ORT) was conducted in a block of West Bengal with 216,825 population through the existing health services facilities. All the grassroot level, health workers including their supervisors at various levels were trained regarding the management of patients of diarrhoea with mild to moderate degree of dehydration, by ORT. Another block in the same district with similar demographic features where this intervention was not provided served as control. After 22 months of observation, it was evident that despite adequate training, the performance of Community Health Guides (CHGs) and Anganwadi Workers (AWWs) was not encouraging because of the low utilization of both home available fluids (32.0%) and oral rehydration solution (18.0%) in the study area. Similarly, diarrhoea associated mortality could not be reduced significantly. Lack of motivation and failure to maintain sustained level of skill by the CHGs and AWWs constitute the major bottlenecks for the successful implementation of the programme at the community level.

PIP: Between April 1985-January 1987, researchers conducted a 3 stage operational study of oral rehydration therapy (ORT) implementation in 2 rural blocks of Hooghly district in West Bengal, India. ORT implementation only occurred in 1 block. The stages included training of community health guides (CHGs) and Anganwadi workers (AWWs); monitoring, supervision, and logistic support; and health and practices surveys. Home available fluids (HAF) usage rate increased from 31-53% in the study block, but fell to only 32% by January 1987. In fact, the initial and final HAF usage rates for the study block were comparable to those of the control block (31% vs. 28.4% and 32% vs. 30%, respectively). Moreover the corresponding figures for oral rehydration solution (ORS) use stood at 13% vs. 8% and 18% vs. 18%). Despite several CHG and AWW training sessions on informing mothers to use ORT in adequate amounts as early as possible during a diarrheal episode, only 12.4% of mothers ever educated by a CHG/AWW knew to do so. In fact, none of the mothers administered ORT early or in adequate amounts. Furthermore diarrhea related mortality remained essentially the same in the study area throughout the study (2-2.8) and indeed the lowest rate (1.7) was in the control area in April 1986. Even though mothers in the study block were significantly more likely to know about oral rehydration solution (ORS) and the availability of free treatment for diarrhea in the village (57% vs. 26% and 34% vs. 13% respectively; p.05), no difference in use of HAF and ORS during diarrhea occurred (26.8% vs. 20% and 11% vs. 12% respectively). The researchers concluded that the major obstacles for improvement of HAF and ORS use were lack of motivation and the CHGs and AWWs inability to maintain a sustained skill level.

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