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The redistribution of residual strains in autofrettaged thick-walled steel tubes resulting from the introduction of holes machined at a radial distance, 50% of the plastic boundary has been investigated with neutron diffraction and finite-elements. In the high compressive region, the redistribution is observed to be localized close to the hole. On the outer section of the hole, the redistribution is less dramatic, but extends up to the plastic boundary. A finite-element simulation of the redistribution of the residual stresses based on an equivalent thermal field approach, based on the measured residual strain values in the solid tube, is also presented. [ABSTRACT FROM AUTHOR]

Seroprevalence was used to evaluate the vaccination programme in the Elim health ward of Gazankulu. Antibodies to measles and polio were measured in 1-6-year-old children together with vaccination status. In 224 children studied using a cluster sampling technique, vaccine coverage was found to be 86% for measles and over 90% for polio and diphtheria, pertussis and tetanus. It was difficult to determine vaccine failure rates accurately; 21% of children were seronegative after having received measles vaccine, 32% who had apparently not been vaccinated had antibodies, while a total of 27% had no measles antibodies. Thirty-nine per cent of children failed to demonstrate antibodies to all 3 types of poliovirus after having received 3 doses of oral polio vaccine, 94% had immunity against type 2, and 76% and 74% were immune to types 1 and 3, respectively. Reasons for diminished effectiveness of vaccination programmes are cited; in this study it was probably due to decreased vaccine efficacy related to inadequacies in the cold-chain. Recommendations are that seroprevalence studies are useful, but only after vaccine coverage and the cold-chain have been optimised.

Oral rehydration therapy (ORT) is effective in preventing dehydration during acute gastro-enteritis, thus decreasing morbidity and mortality. There is, however, reluctance among mothers and child-minders to use ORT when faced with the crisis of acute diarrhoea. This study describes the effects of a health education campaign, using the Morley (sugar and salt) spoon, on knowledge and practice of ORT in one community in Gazankulu, and compares care group (CG) with non-care group (non-CG) members. Two years after its introduction, the Morley spoon was still the most commonly used method of preparing oral rehydration solution (ORS). Ninety-seven per cent of CG members could produce the spoon when asked to, as opposed to 55% of non-CG members (P less than 0.001). Eighty-two per cent of respondents had actually used ORT in the past. Fifty-three per cent mixed the ORS incorrectly. Sixty-one per cent believed that ORT would stop diarrhoea and 29% that it was used for rehydration. Only 26% would give ORS after every loose stool, but 54% would give ORT until the diarrhoea has stopped. Fifty-nine per cent of women would feed their children soft porridge, 20% would continue breast-feeding, and 2% would starve the child while it had diarrhoea. Women who had retained the Morley spoon showed a greater knowledge of ORT (P less than 0.005) and had used ORT more often in the past (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of the immunisation status of children under the age of 5 years in the Elim health ward was undertaken in September 1985. A modified EPI technique for random cluster sampling was used. The advantages of this modification are discussed. In total, 480 children were selected. Of these, 83.5% possessed a 'Road to Health' card, 93.5% had had 3 or 4 doses of DPT vaccine, 92.1% had had 3 or 4 doses of polio vaccine, and 84.3% had had 1 dose of measles vaccine. The percentage of children of 18 months and older who received a fourth dose of either DPT or polio vaccine was 65.9% and 68.5% respectively. The vaccination status of younger children is better than that of older children and this is probably due to recent improvements in the vaccination services. It is recommended that the proportion of children who receive a fourth dose of DPT and polio vaccine should be increased and that completed vaccination is made an entrance requirement for primary schools.

The vaccine cold-chain is a fundamental component of any immunisation programme. This study used chemical-based temperature indicators to monitor the cold-chain constantly in the Elim Hospital health ward of Gazankulu. It was found that the cold-chain was adequately maintained at the hospital, but that as vaccine travelled towards the periphery severe breaks in the cold-chain occurred. Eighteen per cent of vaccines at the Elim Hospital store and up to 90% at the periphery were potentially exposed to temperatures high enough and for a sufficient length of time to have affected their potency. More emphasis needs to be placed on maintaining the cold-chain if we are to reach to EPI's goal of immunisation for all children by the year 1990.

Following the outbreak of poliomyelitis in Gazankulu in 1982, the immunisation services in Gazankulu were thoroughly examined. As a result of this, a comprehensive immunisation policy for Gazankulu was accepted in November 1986. The broad aim of the policy is to provide effective immunisation to all Gazankulu residents against tuberculosis, diphtheria, pertussis, tetanus, poliomyelitis and measles. A specific objective is that by the end of 1987, 85% of under-5s should have been vaccinated against these six diseases and by the end of 1990 this percentage should be 97%. The detailed strategies to reach these objectives are highlighted. Within the framework of the objectives, the policy allows different areas to formulate individual strategies. Programme monitoring and community involvement are two crucial aspects of the policy and these are discussed in detail. The early successes and difficulities in implementing this policy are discussed.