Neonatal calf diarrhea also known as scours is a primary cause of illness and death in young, unweaned calves. Of the several viral, bacterial and protozoal intestinal pathogens associated with calf diarrhea, the most recognized pathogens include Cryptosporidium species, bovine coronavirus and bovine rotavirus group A1. Prevalence of infections by these pathogens varies due to geographic locations, production type (beef/dairy), age, and sensitivity and specificity of the diagnostic tests used for detection.
There are four Cryptosporidium species that are known to infect cattle (Cryptosporidium parvum, Cryptosporidium bovis, Cryptosporidium andersoni, and the Cryptosporidium deer-like genotype). Occurrence of these infections is primarily age-related. C. parvum is the only zoonotic species found in cattle and accounts for about 85% of the Cryptosporidium infections in pre-weaned calves and only 1% in post-weaned calves. Cryptosporidium parvum infections in calves usually occur between 3 to 21 days of age but seldom occur after 3 months of age. C. bovis, C. andersoni, and the Cryptosporidium deer-like genotype are usually known to infect post-weaned calves and old cattle2.
TVMDL recommends collecting 1-2 grams of fresh fecal/stool samples or fecal swabs during acute infection. Ideally, transport to the laboratory with cold packs in plastic leak-proof containers within 24 hours of collection3.
The Calf Diarrhea Multiplex (rtPCR) can simultaneously detect three pathogens: Cryptosporidium species, bovine coronavirus and bovine rotavirus group A from bovine stool specimens.
The assay uses a single protocol to detect these pathogens and includes an internal positive control to monitor nucleic acid purification and amplification efficiency, enabling quick turnaround time. TVMDL professionals are also available for interpretation and consultation on herd health diagnostics.
TVMDL also offers a Cryptosporidium sp. (rtPCR) test as another option for diagnosing cryptosporidiosis.
References:
1) Foster DM, Smith GW: 2009, Pathophysiology of diarrhea in calves. Vet Clin North Am Food Anim Pract 25: 13-36, xi.
2) Thompson HP, Dooley JSG, Kenny J, McCoy M, Lowery CJ, Moore JE, Xiao L: 2007, Genotypes and subtypes of Cryptosporidium spp. in neonatal calves in Northern Ireland. Parasitol Res 100:619-624.
3) OIE Terrestrial Manual: 2008, Cryptosporidiosis. Chapter 2.9.4. 1192-1215.
4) Schroeder ME, Bounpheng MA, Rodgers S, Baker RJ, Black W, Naikare HK, Velayudhan BT, Sneed L, Szonyi B, Clavijo A: 2012, Development and performance evaluation of calf diarrhea pathogen nucleic acid purification and detection workflow. Journal of Veterinary Diagnostic Investigation 24(5) 945-953.