Seasonal variation in the prevalence and molecular epidemiology of Cryptosporidium infection in dairy cattle in the New York City Watershed

Abstract

We conducted cross-sectional studies in the New York City Watershed to ensure a valid estimate of the risk associated with Cryptosporidium infection in dairy herds. Our aims were to obtain species-specific estimates of the prevalence of Cryptosporidium in dairy cattle and to investigate seasonal variations in prevalence. We validated our empirical estimates using a Bayesian approach. Samples were collected on 32 study farms, once in each of 3 different seasons using an age-stratified sampling design. The overall prevalence of Cryptosporidium parvum-like species and Cryptosporidium andersoni among the 1911 animals tested by the flotation method was 5% and 1%, respectively. Among preweaned calves (<65 days of age), the prevalence of C. parvum-like species was twice as high in the summer (26%) compared with the winter (11%). Herd prevalence showed the same seasonal trend. Preweaned calves were also shedding C. andersoni at an average intensity of 20 oocysts per gram of feces. We did not detect C. parvum-like oocysts in cattle older than 5 months. Sequencing of a portion of the 18s rRNA gene revealed that in the summer, 42% of the C. parvum-like oocysts shed by preweaned calves were zoonotic, compared with >74% during the rest of the year. Both empirical and stochastic methods revealed a summer peak in the prevalence of C. parvum-like oocysts in preweaned calves. Determining whether seasonal variation in the prevalence and proportion of Cryptosporidium species shed by preweaned calves is due to management practices or ecological factors will have important implications for effective control of this parasite.

Prevalence and Genetic Characterization of Cryptosporidium in Yaks in Qinghai Province of China

“…Unfortunately, we did not study the prevalence of Cryptosporidium in the autumn, so cannot comment on this season. We detected C. bovis infection in all studied seasons, in contrast to previous reports that C. bovis prevalence in pre-weaned calves peaked in autumn in China and in summer in the United States [34], [41].…”

“…in yaks peaked in the spring (28.4%), declining in the summer (22.0%), and descended to the lowest levels in the winter (17.5%). This is in accordance with the report that Cryptosporidium infection of dairy calves peaks in spring [50], but is contrary to Szonyi et al [41] and Wang et al [34] who found that summer was the dominant infection season in the United States and China, while Hamnes et al [53] found the highest prevalence in winter in Norway. The reasons for the seasonal variation in infection rates in yaks may be explained as follows: In spring in Qinghai Province, new grass has not yet grown, and yaks are fasted over the long winter.…”

“…Similar to most studies of dairy calves [7], [34], [36], [40], [41], we found that C. ryanae was the least frequently detected species in yaks, in contrast to other studies of water buffaloes and beef calves in Egypt and Vietnam which reported that C. ryanae was most prevalent [42], [43]. Moreover, a recent survey reported that C. ryanae was the only Cryptosporidium species identified in zebu cattle and water buffaloes in Nepal [44].…”

“…Several studies have reported that seasonal shift could influence the Cryptosporidium infection levels in dairy cattle [34], [41], [53]. We found that the prevalence of Cryptosporidium spp.…”

Characteristics of Cryptosporidium Transmission in Preweaned Dairy Cattle in Henan, China

“…However, there appeared to be a seasonal shift in the dominant Cryptosporidium species in preweaned calves, with C. parvum peaking in summer and C. bovis peaking in autumn and winter. This finding is somewhat different from the recent observation of C. bovis dominance in summer and C. parvum dominance in spring and winter in dairy cattle in New York (38). More large studies in different areas are needed to determine whether these differences are attributable to difference in animal management.…”