There's Something in the Water: An analysis of the Impact of Climate on Legionellosis Incidence in the South Atlantic Region of the United States

Abstract

Legionellosis is a human respiratory disease caused by the inhalation of particulates contaminated with Legionella ssp. Legionella ssp. are thought to exist ubiquitously in fresh water sources and are a major bacterial contributor to the occurrence of community acquired pneumonia which is a major cause of morbidity and mortality, particularly in older populations. Climatic variables such as precipitation and temperature are thought to be associated with legionellosis incidence. However, in 2003, the South Atlantic region of the United states began experiencing a rise in the number of legionellosis cases reported despite the fact that many states in this area experienced decreased rainfall. To interrogate the relationship between climatic variables and Legionella’s incidence in this region, statistical analysis was conducted on the association between annual legionellosis incidence, annual precipitation totals, and annual average temperatures from January 1979 to December 2016. Additionally, monthly variables examined for regional states in which data was available. Annual increases in temperature and population were found to be associated with the increasing number of cases reported in the region while annual precipitation was not found to be a statistically significant variable in predicting legionellosis incidence. However, on an annual time scale no observable trend in regional precipitation was observed during this time period making it difficult to determine the effect of precipitation on the disease. Further research in into climatic variables associated with the disease is needed as a better understanding of environmental factors that increase exposure and transmission of Legionella can help in the identification of at risk communities and provide opportunities for prevention.