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Background: Seasonal fluctuation in suicide has been observed in many populations. High temperature may contribute to this, but the effect of short-term fluctuations in temperature on suicide rates has not been studied.Aims: To assess the relationship between daily temperature and daily suicide counts in England and Wales between 1 January 1993 and 31 December 2003 and to establish whether heatwaves are associated with increased mortality from suicide.Method: Time-series regression analysis was used to explore and quantify the relationship between daily suicide counts and daily temperature. The impact of two heatwaves on suicide was estimated.Results: No spring or summer peak in suicide was found. Above 18 degrees C, each 1 degrees C increase in mean temperature was associated with a 3.8 and 5.0% rise in suicide and violent suicide respectively. Suicide increased by 46.9% during the 1995 heatwave, whereas no change was seen during the 2003 heat wave.Conclusions: There is increased risk of suicide during hot weather. [ABSTRACT FROM AUTHOR]

Since new drinking water regulations were implemented in England and Wales in 2000, cryptosporidiosis has been significantly reduced in the first half of the year but not in the second. We estimate an annual reduction in disease of 905 reported cases and approximately 6,700 total cases. [ABSTRACT FROM AUTHOR]

Background: Acute associations between mortality and ozone are largely accepted, though recent evidence is less conclusive. Evidence on ozone-heat interaction is sparse. We assess effects of ozone, heat, and their interaction, on mortality in Britain., Methods: Acute effects of summer ozone on mortality were estimated using data from 15 conurbations in England and Wales (May-September, 1993-2003). 2-day means of daily maximum 8-h ozone were entered into case series analyses, controlling for particulate matter with aerodynamic diameter of <10 μm, natural cubic splines of temperature, and other factors. Heat effects were estimated, comparing adjusted mortality rates at 97.5th and 75th percentiles of 2-day mean temperature. A separate model employed interaction terms to assess whether ozone effects increased on 'hot days' (where 2-day mean temperature exceeded the whole-year 95th percentile). Other heat metrics, and non-linear ozone effects, were also examined., Results: Adverse ozone and heat effects occurred in nearly all conurbations. The mean mortality rate ratio for heat effect across conurbations was 1.071 (1.050-1.093). The mean ozone rate ratio was 1.003 per 10 μg/m(3) ozone increase (95% CI 1.001 to 1.005). On 'hot days' the mean ozone effect reached 1.006 (1.002-1.009) per 10 μg/m(3), though ozone-heat interaction was significant in London only. On substituting maximum for mean temperature, the overall ozone effect reduced to null, though evidence remained of effects on hot days, particularly in London. An estimated ozone effect threshold was below current guidelines in 'mean temperature' models., Conclusion: While heat showed robust effects on summer mortality, estimates for ozone depended upon the modelling of temperature. However, there was some evidence that ozone effects were worse on hot days, whichever temperature measure was used.

Infectious intestinal disease (IID) surveillance data are an under-utilised information source on illness geography. This paper uses a case study of cryptosporidiosis in England and Wales to demonstrate how these data can be converted into area-based rates and the factors underlying illness geography investigated. Ascertainment bias is common in surveillance datasets, and we develop techniques to investigate and control this. Rural areas, locations with many livestock and localities with poor water treatment had elevated levels of cryptosporidiosis. These findings accord with previous research validating the techniques developed. Their use in future studies investigating IID geography is therefore recommended.

Outbreaks of cryptosporidiosis have been linked to weather patterns such as heavy precipitation. However, outbreaks only account for a small percentage of all cryptosporidiosis cases and so the causes of the majority of cases are uncertain. This study assessed the role of environmental factors in all cases of cryptosporidiosis by using ordinary least-squares regression to examine the relationship between the monthly cryptosporidiosis rate, and the weather and river flows in England and Wales between 1989 and 1996. Between April and July the cryptosporidiosis rate was positively related to maximum river flow in the current month. Between August and November cryptosporidiosis was also positively linked to maximum river flows in the current month but only after accounting for the previous month's temperature, precipitation and monthly cryptosporidiosis rate. No associations were found between December and March. Through an understanding of the environmental processes at work, these relationships are all consistent with an animal to human transmission pathway especially as the relationships vary throughout the year. This study therefore indicates the importance of an animal to human transmission pathway for all cases of cryptosporidiosis.