Managing a large outbreak of cryptosporidiosis: how to investigate and when to decide to lift a 'boil water' notice.

The largest outbreak of cryptosporidiosis reported in the United Kingdom, involving 575 confirmed cases (of which 474 met an agreed case definition), occurred in the county of Devon during August and September of 1995. The descriptive epidemiology supports the hypothesis that the outbreak was associated with the consumption of cold tap water in the area served by a particular water treatment works. Cryptosporidium oocysts were detected in treated water samples at the time of the outbreak. Although the epidemiological analysis provided strong circumstantial evidence of a waterborne outbreak, the data were not recorded in a manner that made them admissible in criminal proceedings taken by the Drinking Water Inspectorate against the water company involved. The need to carry out an analytical study in conjunction with the identification and characterisation of the pathogen in the drinking water and the practicalities of agreeing criteria for lifting a 'boil water' notice are discussed.

Morbidity, deprivation, and antidepressant prescribing in general practice.

BACKGROUND: Although the link between depression, unemployment, and measures of deprivation and morbidity has been previously documented, the relationship between general practice prescribing of antidepressants, morbidity, and the social demography of general practice populations is poorly understood. AIM: To consider whether morbidity and the social demography of general practice populations influence the prescribing costs of individual practices. METHOD: Data were analysed, using a forward stepwise regression procedure, of all 78 practices served by the Cornwall and Isles of Scilly Health Authority. Data on prescribing for antidepressants were provided by the Prescription Pricing Authority for the period from July to December 1995 and converted into defined daily doses (DDDs) to standardize for the variation in prescribing practice between general practitioners. RESULTS: A significant positive correlation exists between the rates of prescribing DDDs of antidepressants by general practices and the prevalence of permanent sickness in the areas in which these practices serve. CONCLUSION: Demonstrating an association between morbidity and prescribing rates for depression may prove helpful in setting prescribing budgets.

'My ward is more deprived than yours'.

BACKGROUND: Increasingly, additional resources for infrastructure development and healthcare are directed at deprived areas. The commitment of the present government to reducing inequalities in health is likely to focus attention on identifying and providing special help to areas considered to be particularly deprived. This study compares the use of different deprivation measures at electoral ward level to rank wards according to deprivation and illustrates how the use of different deprivation measures may influence resourcing decisions. METHODS: The 20 local authority electoral wards making up the city of Plymouth, Devon, were studied. Some of the wards within Plymouth are amongst the most deprived in England. The scores for each ward for different measures of deprivation--Townsend, Jarman, the Department of Environment's Index of Local Conditions and Breadline Britain--were calculated and the wards ranked according to the deprivation score for each measure. Decisions on funding bids and resource allocation for wards within Plymouth were reviewed in the light of the relative deprivation status of the wards according to the various measures. RESULTS: The ranking of electoral wards for the selected measures of deprivation showed variation according to the measure used. The measure of deprivation chosen may have influenced resourcing decisions. CONCLUSION: Measures of deprivation are closely correlated one with another. However, by judicious choice of the deprivation measure used a ward can achieve a marked change in rank order. This may exert considerable influence on the decisions made by government departments, local authorities and health authorities when allocating resources.

Needs assessment at a practice level; using routine data in a meaningful way.

BACKGROUND: General practitioners and primary health care teams are asked to take an increasing role in assessing needs and priorities for the people they serve. We describe a model, using routinely available data, to provide health and social information to all general practices in an English Health Authority (South & West Devon, population 586,000, containing 103 general practices) to inform practice-based needs assessment. METHOD: Practice-coded hospital activity information was used where available, otherwise the FHSA population register was used to assign spatially referenced data (OPCS birth files, OPCS mortality files, cancer registration files and census information) to practices. Additionally, indicative incidences and prevalences were calculated for each practice using age- and sex-specific rates derived from national surveys (Survey of Morbidity Statistics from General Practice and the OPCS Health Survey for England). RESULTS: Information was produced for each practice on births, lifestyle, social factors, incidence and prevalence, hospital activity and mortality. Patient numbers rather than rates were presented. General practitioners commented that this approach gave an understanding of the size of health and social problems and fitted with the concept of numbers needed to treat. CONCLUSION: Public health involvement in practice-based needs assessment is essential. Current public health input has mainly been on a selective individual practice basis and is very resource intensive. This approach allows all practices to have immediate access to a wide range of health and social information presented in a way that is easily understood and informs debate on health needs within the practice.

In vivo studies of whole ricin monoclonal antibody immunoconjugates for the treatment of murine tumours.

Ricin is a highly potent toxin which binds to cells via galactose binding sites on the B chain; the toxicity is manifest by the A chain and most studies with immunotoxins have used ricin A chain-antibody conjugates. We have previously described a method for the coupling of whole ricin to monoclonal antibody (MoAb) so that the galactose binding sites on the B chain are blocked; these conjugates are not non-specifically toxic. Whole ricin-MoAb conjugates were examined in vivo for their stability, clearance rates and toxicity, and these were compared with modified ricin-MoAb conjugates produced by periodate treatment of ricin. First, the biological half-life of whole ricin or modified ricin was determined and indicated that while ricin was rapidly cleared from the circulation (t 1/2 = 4.5 +/- 0.5 min) compared with modified ricin (t 1/2 = 17 +/- 1 min), covalent linkage of native ricin to MoAb increased the blood circulation time of the toxin (t 1/2 = 22 +/- 1 min). Immunotoxins synthesized with the Ly-2.1 MoAb using native or modified (deglycosylated) ricin were compared in vivo. In two different models anti-Ly-2.1 immunotoxins could be shown to be effective in vivo: (i) intraperitoneal tumours, thymomas grown in the peritoneal cavity could be completely eradicated by ricin-MoAb; (ii) subcutaneous tumours, mice with tumours approximately 0.75 cm in diameter received intravenous doses of the whole ricin-MoAb and a substantial reduction in tumour size was achieved. Thus whole ricin-antibody conjugates made with the galactose binding site blocked combine the advantage of high potency with high specificity (which was previously lacking in intact ricin conjugates) and can be successfully used in vivo to treat tumours.