الفهرس 
-Introduction
Diagnosis of Rota and Corona viruses’ infection in neonatal calvesOnly 14 pages are availabe for public view
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Abstract
Healthy calf is a cornerstone of animal breeding for beef and/or milk production. Calf diarrhea is a common syndrome causing colossal economic losses in term of morbidity, dwindle growth rate, costs of therapeutic and control measures, and deaths. Rotavirus and Coronavirus are major pathogens of calf diarrhea. Clinical and epidemiological aspects of calves’ enteritis associated with Rota and Corona viruses in Assiut Governorate, Upper Egypt were aimed in the present study.
During the period of investigation (13 consecutive months), a total number of 140 neonatal calves were subsequently inspected, carefully examined and thereafter subjected to serological and molecular diagnosis for the subsistence of Rota and Corona viruses’ infection.
Comprehensively, the infection rate of Rotavirus and Coronavirus infection of the examined calves was 21.43 % (30/140) and 2.13 % (2/94), respectively. The main clinical findings in Rotavirus and Coronavirus enteritis varied from mild, moderate to severe diarrhea. Feces were mucoid yellowish with and/or without flakes of clotted blood with undigested material substances. Some calves were carried Rotavirus infection in their feces without clinical abnormalities. The diseased calves showed weakness, unable to stand, arched back with straining during defecation, anorexia, variable degree of dehydration. Body temperature, respiratory rate and heart rate were high in some cases or were low and normal in others. The diseased calves with Coronavirus enteritis were suffering from mild respiratory signs in association with mild enteritis.
The serological and molecular diagnosis by using LAT and RT-PCR indicated that positive samples of Rotavirus infection were 21.43% (30/140) and 8% (4/50), respectively, referring to sensitivity and feasibility of LAT in diagnosing of calf’s diarrhea associated with Rotavirus infection. Furthermore, ELISA and RT-PCR were used in diagnosing of BCoV infection and found that positive samples were 2.13% (2/94) and 4% (2/50), respectively. ELISA is easier than RT-PCR and RT-PCR can be used in diagnosis of Coronavirus infection.
Commercially, RT-PCR is still a precious technique in our laboratories in comparison with ELISA. LAT is a cheapest test in diagnosing of enteric viral pathogens.
Epidemiologically, for studying the relationship between rate of Rotavirus infection and ages of calves, the examined calves (n= 140) were grouped into 7 age groups (3 days-1week, >1-2, >2-3, >3-4, >4-5, <5-7 and >7-12 weeks). It was found that there was a strong negative correlation (r= -0.918) between age of examined calves and Rotavirus infection. The infection rate was gradually declined by increasing of age of the calves. The rate of Rotavirus infection decreased due to immune system of calves is not fully matured to handle Rotavirus infection. On the other side, Coronavirus infection was found in calves at >4-7 weeks due to lack or decrease of colostral antibodies. Such study refers strongly to the pivotal role of vaccination programs of calves against Rotavirus and Coronavirus infection.
In regard to the effect of sex difference in rate of infection with Rota and Corona viruses, the present work revealed that sex of calves had no role in rate of infection statistically.
Effect of locality in percent of infection with Rota and Corona viruses was epidemiologically investigated and found that there was no significant difference between rate of infection with Rotavirus in the individual cases that admitted to Veterinary Teaching Hospital, Assiut University in comparison with calves on farms (Faculty of Agriculture farm and Abnoub El-Hamam farm). But Coronavirus was higher in calves on farms in comparison with the individual cases. Such epidemiological notes was interpreted and discussed.
Effect of species and breed susceptibilities of examined calves to Rota and Corona viruses’ infection were monitored in the current study and concluded that there were no significance difference in breed susceptibility of calves (Native, Friesian and Holstein) to infection, all were infected. Moreover the susceptibility rate of examined cattle and buffaloes’ calves were statistically parallel.
Climatologically, the most positive cases of Rotavirus and Coronavirus infection were reported in cold months (The second half of November, December, January and February) of Assiut Governorate. Conversely the lower infection rate of Rotavirus was recorded in hot months. Such variations was interpreted and discussed.
Fascinatingly, Rotavirus antigen was serologically captured in fecal material of two enteric cases of examined calves coming from vaccinated dams that vaccinated by a commercially prepared inactivated vaccine contains Rota and Corona viruses plus others. This may concludes that vaccination programs alone is not fully sufficient for preventive measures against Rota and Corona viruses’ infection and must synchronized with good hygienic measures. Furthermore, passive transfer of antibody from cows/buffaloes to their neonates as early as possible is a crucial goal.