Legionnaires disease cases increase by 230% in USA

A study of data available for Legionellosis cases in New York between 2000 and 2011 carried out by CDC and reported in JAMA, has uncovered some remarkable trends which provide some guidance for developing policy on the management of risks for Legionnaires disease.

The incidence of the illness in New York City has increased by 230% in recent years, from 0.83 cases per 100 000 population in 2002 to 2.74 per 100 000 in 2009. The incidence of disease in residents more than 70 years old increased by a staggering 826%. Although only 11.7% more cases were found among those in care homes, 3 times as many of these cases resulted in the death of the patient than those not in care homes.

Other findings include that those who are involved in outdoor occupations like construction, transport, protection services and cleaning services were the groups most at risk. Men are more at risk than women. Those with risk factors, like smoker, diabetes or mellitus, accounted for 88.2% of all cases.

Almost 75% of cases occurred in the summer months, clearly linking the disease to warmer water temperatures. The Legionella bug grows quickly in water temperatures over 20degrees centigrade.

People living in poorer areas are more than 2.5 times at risk than residents of higher income areas. The report links this to poor maintenance of water systems.

Once again poor maintenance is cited as a causative factor and while it seems simplistic to state that water systems need to be maintained to prevent disease, while there is no requirement to monitor the condition of water systems through regular testing, maintenance will continue to be sub-standard. This report clearly finds that the poor, the old and those working in ‘at risk’ occupations will pay the price, and will continue to be used as the indicators of sub-standard maintenance while the authorities hold out against a requirement to prove that water systems conform to acceptable standards.