Description Of The Foodborne Outbreaks For Both Parasites

Cryptosporidium can be found worldwide and infects a variety of hosts, including humans. The incidence of Cryptosporidium can vary depending upon the population and location from 0.6 to 20%. In the U.S., cryptosporidiosis is associated with 0.4 to 1% of cases of diarrhea [52]. The cryptosporidium oocyst is resistant to normal environmental conditions, but desiccation can render oocysts noninfectious. Foodborne outbreaks of cryptosporidium have been associated with foods prepared in homes, suggesting direct contamination by food handlers. In Maine, in1993, an outbreak was linked to unpasteurized apple cider. A farm with livestock used dropped apples for the preparation of the apple cider [24]. In 1995, in Minnesota, chicken salad was implicated in 15 cases of cryptosporidiosis. Another outbreak involving apple cider occurred in 1996 in New York [53]. Sixty-six persons developed cryptosporidiosis and one died. In 1997, 54 cases of cryptosporidiosis were probably connected to the consumption of green onions. Two of the 14 food preparers were positive for cryptosporidium. In 1998 an outbreak was associated with consumption of meals in one of two cafeterias of a university in Washington D.C. Epidemiological investigation concluded that the outbreak was caused by C. hominis and the most probable source was an ill food handler who prepared raw produce [25].

Milk, salad, sausage, and tripe have also been suspect foods in travelers with cryptosporidiosis entering the U.S. from Mexico, the U.K., and Australia. Although no cases of cryptosporidiosis associated with shellfish have been reported, the presence of human strain of cryptosporidium has been reported in mussels and oysters retailed for human consumption [54-57].

Cyclospora is endemic in certain countries of tropical regions. Much of what we know about cyclospora has resulted from studies performed in those settings. A disease of the tropics and developing countries found its way to the developed countries when the latter started importing produce that is in demand throughout the year. If cyclospora is endemic in such exporting countries, it is possible that if good agricultural practices (GAPs) are not implemented in those particular fields, human feces can be carried to the products, either by crop manipulation with contaminated hands, or contaminated irrigation water. Cyclospora is highly resistant to environmental conditions and will attach to the surface of the produce and remain viable for longer periods of time. Most fecal contaminants may not remain viable for long periods of time, thus explaining why other foodborne outbreaks have not been reported in parallel with cyclospora outbreaks.

Four commodities have been implicated with cyclospora foodborne outbreaks: raspberries, basil, lettuce, and snow peas. Since the early 1990s sporadic cases of cyclosporiasis were reported in the U.S., but no source of contamination was identified. The first large cyclospora outbreak occurred in 1995 in Florida. Strawberries were initially implicated in the outbreak, but later epidemiological investigations suggested that raspberries were responsible. In 1996, 1465 cases of cyclosporiasis were reported in 20 states in the U.S. In 1997, 41 clusters comprising 762 cases were reported during the months of April and May in 9 states. Raspberries, basil, and lettuce were implicated in this outbreak. Also during April to June of the same year, 250 laboratory-confirmed sporadic cases were reported. In all instances, imported raspberries were associated with the outbreak. As a result of this, Guatemala voluntarily suspended the exportation of raspberries. In 1998 a few sporadic cases of cyclosporiasis were reported in the U.S., but Canada continued to import berries from Guatemala and experienced a large outbreak [58,59].

Surveys of fresh produce have described the presence of cyclospora [40,41,46]. In 2004 the U.S. Food and Drug Administration (FDA) issued an alert to consumers that two outbreak clusters of cyclosporiasis may be associated with raw basil and mesclun/spring salads served in Texas and Illinois. In February 2004 approximately 54 individuals in Wheaton, Illinois, and 38 people in Irvin, Texas, were stricken with cyclosporiasis. During June and July 2004 approximately 50 potential cases of cyclosporiasis were associated with a residential facility. Epidemiological and traceback studies linked the cases to consumption of raw Guatemalan snow peas [60]. Throughout the years, sporadic cases of cyclospora continue to occur in the U.S., suggesting that cyclospora is either being introduced to the U.S. by imported produce, or by food handlers who are carriers of this parasite. More studies are needed to determine the actual distribution of cyclospora in the U.S., both in human populations and environmental samples.

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