Periurban outbreaks of bovine calf scours in Northern India caused byCryptosporidiumin association with other enteropathogens

Abstract

SUMMARYBovine calf scours reported to be caused by multiple aetiologies resulting in heavy mortality in unweaned calves and huge economic loss to the dairy farmers. Among these, cryptosporidiosis is an emerging waterborne zoonoses and one of the important causes of neonatal calf diarrhoea. Poor immune response coupled with primary cryptosporidial infections predispose neonatal calves to multiple secondary infections resulting in their deaths. In the present study, faecal samples from 100 diarrhoeic calves randomly picked up out of 17 outbreaks of bovine calf diarrhoea in periurban Ludhiana, Punjab in Northern India were subjected to conventional (microscopy, modified Zeihl–Neelsen (mZN) staining) and immunological and molecular techniques (faecal antigen capture ELISA and PCR) for detection of primaryCryptosporidium parvuminfection as well as other frequently reported concurrent pathogens,viz. rotavirus and coronavirus,Salmonellaspp.,Escherichia coli,Clostridium perfringensandEimeriaspp. The faecal antigen capture ELISA and PCR revealed 35% prevalence ofC. parvumin contrast to 25% by mZN staining with a relatively higher prevalence (66·7%) in younger (8–14-day-old) calves. The detection rate of the other enteropathogens associated withC. parvumwas 45·71% forC. perfringensfollowed bySalmonellaspp (40·0%), rotavirus (36·0%), coronavirus (16·0%),E. coli(12·0%) andEimeriaspp (4·0%) The sensitivity for detection ofC. parvumby ELISA and mZN staining in comparison to PCR was 97·14% and 72·72%, respectively. An important finding of the study was thatC. parvumalone was found in only 10% of the diarrhoeic faecal samples, whereas, majority of the samples (90%) showed mixed infections ranging from a combination of two to five agents. This is the first documentary proof ofC. parvumand associated pathogens responsible for severe periurban outbreaks of bovine calf diarrhoea culminating in heavy mortality from Northern India.