科研之友
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摘要
Bovine cryptosporidiosis is mainly caused by four distinct species: Cryptosporidium parvum, C. bovis, C. ryanae and C. andersoni. The first, C. parvum, is a major concern in livestock causing economic losses, in addition to public health impact because of its zoonotic characteristics. The present study aimed to determine the occurrence of different species and subtypes of Cryptosporidium using molecular techniques. A total of 143 fecal samples were collected from calves from three dairy farms located in the state of Rio de Janeiro, Brazil. Saturated sugar centrifugal flotation method was used for the microscopic evaluation of the samples. Among these samples, 19.6% (28) were positive by microscopy, and 82.1% (23) of these 28 samples had their diagnosis confirmed by PCR using 18S as gene target. After sequencing, three species of Cryptosporidium were found to infect calves in different age groups. In pre-weaning phase (<2 months), 10% (3/30) of the calves were infected with C. parvum, whereas 14.2% (16/113) of post-weaning calves (>= 2 months) were observed to be infected with C. andersoni and 1.8% (2/113) by C. ryanae with the latter diagnosed for the first time in the state of Rio de Janeiro. Those samples identified as C. parvum were further characterized at the GP60 locus, and PCR products were cloned. Eight different subtypes (IIaA20G2R1, IIaA20G2R2, IIaA19G2R1, IIaA19G2R2, IIaA18G1R1, IIaA18G2R2, IIaA16G3R2 and IIaA14G2R2) of C. parvum were identified, all belonging to the Ha family subtype, which is considered of high zoonotic potential. The subtypes mentioned above have not yet been detected in Brazilian cattle, and four of these subtypes (IIaA20G2R2, IIaA19G2R2, IIaA18G2R2 and IIaA14G2R2) had not been diagnosed elsewhere in calves until this study.
- 出版日期2014-2
