Ambient maximum temperature as a function of Salmonella food poisoning cases in the Republic of Macedonia

BACKGROUND: Higher temperatures have been associated with higher salmonellosis notifications worldwide. AIMS: The objective of this paper is to assess the seasonal pattern of Salmonella cases among humans. MATERIAL AND METHODS: The relationship between ambient maximum temperature and reports of confirmed cases of Salmonella in the Republic of Macedonia and Skopje during the summer months (i.e. June, July, August and September) beginning in 1998 through 2008 was investigated. The monthly number of reported Salmonella cases and ambient maximum temperatures for Skopje were related to the national number of cases and temperatures recorded during the same timeframe using regression statistical analyses. The Poisson regression model was adapted for the analysis of the data. RESULTS: While a decreasing tendency was registered at the national level, the analysis for Skopje showed an increasing tendency for registration of new salmonella cases. Reported incidents of salmonellosis, were positively associated (P<0.05) with temperature during the summer months. By increasing of the maximum monthly mean temperature of 1° C in Skopje, the salmonellosis incidence increased by 5.2% per month. CONCLUSIONS: The incidence of Salmonella cases in the Macedonian population varies seasonally: the highest values of the Seasonal Index for Salmonella cases were registered in the summer months, i.e. June, July, August and September.