Study on Cryptosporidium contamination in vegetable farms around Tehran.

In recent years, an increase in the number of cases of food-borne illnesses linked to fresh vegetables has been reported. One of the causative agents of these infections is Cryptosporidium and it appears that one route of transmission to humans is food-borne, so fruits and vegetables have important roles. The goal of this study was to determine the level of Cryptosporidium contamination in vegetable farms around Tehran, Iran. A total of 496 samples from 115 vegetable farms in different regions around Tehran (Capital city of Iran) were collected and different types of vegetables were investigated for the parasite in June and July, 2012. A sediment concentration method followed by modified Ziehl-Neelsen's acid-fast staining was used to determine the presence of Cryptosporidium oocysts. Our findings revealed that 6.6% of studied samples were contaminated with Cryptosporidium species. The highest rate of contamination was reported in Bagher Abad (South of Tehran) (11.1%), and green onions were more commonly contaminated (14.8%) than any other vegetables tested. Furthermore, when waste water was used to irrigate vegetable farms, the contamination rate was (33.3%). Statistical analysis showed a correlation between contamination with Cryptosporidium spp. and studied risk factors including: different regions around Tehran, type of vegetables, and type of water used for farm irrigation. Therefore, vegetables may provide a route by which Cryptosporidium can be transmitted to humans, and control strategies should be considered.