Purpose: Describe the frequency and characteristics of melon-associated outbreaks in the United States.
Methods: We reviewed outbreaks reported to CDC’s Foodborne Disease Outbreak Surveillance System during 1973–2011 in which the implicated food was a single melon type, including cantaloupe, watermelon, and honeydew. Published literature and records obtained from investigating agencies were also reviewed.
Results: From 1973–2011, 34 outbreaks caused by melons were reported, resulting in 3,601 reported illnesses, 321 hospitalizations, 45 deaths, and 3 fetal losses. Cantaloupes accounted for 19 of these outbreaks, followed by watermelon (13) and honeydew (2). On average, one melon-associated outbreak was reported each year; this increased from 0.5 outbreaks per year from 1973–1991 to 1.3 from 1992–2011. Half of outbreaks (17) occurred in June–August. Salmonella (19 outbreaks) was the most common etiology reported, followed by norovirus (5 outbreaks). Among the 22 outbreaks with a known source of contamination, 15 were contaminated on-farm, 6 by an ill food worker, and one by cross-contamination. Among outbreaks caused by melons contaminated on-farm, 8 were attributed to imported melons from Mexico and Central America and 7 to domestically-grown melons. Seven outbreaks caused by imported melons were multistate; one occurred only in California. Among the 13 multistate outbreaks, 10 were attributed to cantaloupe contaminated with Salmonella, one to watermelon with pesticide, one to honeydew with Salmonella, and one to cantaloupe with Listeria.
Significance: Recognition and reporting of foodborne disease outbreaks due to melons has increased. Preventive measures focused on reducing on-farm contamination in cantaloupe by bacterial pathogens, including Salmonella and Listeria, would likely decrease the number and severity of melon-associated outbreaks.