Purpose: The purpose of the present work was to investigate the prevalence of foodborne Cryptosporidium and Giardia in young children and in food animals and determine risk factors associated to the infection of the two parasites and discuss strategies to prevent zoonotic foodborne transmission domestic and international.
Methods: Fecal samples were collected from dairy calves in California and young children with diarrhea in Guangzhou, China. Samples were screened for Cryptosporidium oocysts and Giardia cysts using fluorescent microscopy. DNA was extracted from microscopic positive samples and the SSU rRNA genes were amplified for both Cryptosporidium and Giardia. PCR products were purified and sequenced. Sequences were analyzed using the Vector NTI software and the NCBI online Blast tool. Species/genotypes of Cryptosporidium and Giardia were determined by comparison to existing sequences in GenBank and by phylogenetic analysis. Questionnaires were administered to determine socio-economic factors associated to Cryptosporidium/Giardia infection in children and environmental factors and management practices associated to the prevalence of the parasites in food animals.
Results: Total 300 fecal samples were collected from young children in Guangzhou, China and 360 fecal samples were collected from dairy calves in California. Cryptosporidium spp. was detected in approximately 10% of samples from children and 22% of samples from dairy calves. Giardia spp. was detected in approximately 7% of samples from children and 17% from dairy calves. Infections of the two parasites in children were associated to consumption of raw local produce and unpasteurized water and that in animals associated to age and facility sanitation practice. Molecular characterizations are being carried out to determine the unique species and genotypes cause zoonotic foodborne infection.
Significance: Data from the present work suggest that infection of Cryptosporidium and Giardia in children can be reduced through changing eating habits and that in food animals through improved management practice. Strategies are discussed to reduce the transmission of these two pathogens in domestic and international food chain and to prevent zoonotic infection.