Infectious-like spread of an agent leading to increased medical hospital admission in the North East Essex area of the East of England

Abstract

This work documents the spread of a new type of infectious-like outbreak leading to a step-increase in emergency medical admissions. It employs a running 12 month sum of emergency medical admissions to detect step-like changes in admissions from small areas, namely Mid Super Output Area (MSOA) geographical areas and from GP practice enrolled patients. A general 25% step-like increase in emergency medical admissions occurred around November of 2008 in North East Essex due to gradual spatial spread of an infectious-like agent. Earliest incidence seems to be around August 2007 at a GP surgery in the Castle ward of Colchester leading to a 21% increase in medical admissions. The next major incidence appears to be around January of 2008 at a GP Surgery in the Shrub End ward of Colchester with a 32% increase in admissions. Sporadic occurrences can be seen in April and May of 2008 in four small areas with 21% to 65% increases in medical admissions. The major outbreak occurred in October, November and December of 2008, hence the apparent November 2008 date seen in the aggregated data for the entire area. Further sporadic spread continues through to October 2009. Several small areas appear to have escaped the outbreak, notably a rural GP practice in the village of Lawford and an area of Colchester dominated by student bed sits. More deprived elderly communities represent the social groups most affected. The outbreak shows strong age dependence which is reminiscent of what is termed ‘original antigenic sin’, i.e. age at first exposure to a strain of an infectious agent determines the quality of the immune response to later exposure to different strains of the same agent. There is evidence to suggest that residents of nursing homes are affected earlier and more strongly than others while those who die in hospital show only a modest increase, i.e. the infection generally leads to sustained poor health rather than death. Analysis of the primary diagnoses for those admitted to hospital strongly suggests that the agent may be the common herpes virus cytomegalovirus and this is consistent with the apparent time cascade in disease which emanates out of each outbreak. Other explanations may be possible. These findings have profound public health implications regarding the infectious origin of disease, to the funding formula used to distribute health care funds both in the UK and elsewhere and to the interpretation of age-standardized admission rates for medical admissions.