A Retrospective Cohort Study of an Outbreak of Cryptosporidiosis among Veterinary Students

Abstract

An outbreak of gastrointestinal illness occurred among a cohort of 56 veterinary technology and 100 veterinary science students at Massey University over an eight-week period in 2013. This coincided with calving in New Zealand’s seasonal dairy farming system and a time when calves with diarrhoea are commonly seen by veterinarians. Laboratory and epidemiological investigations were instigated by MidCentral Public Health Service (MCPHS) in conjunction with the Institute of Veterinary, Animal and Biomedical Sciences (IVABS) at Massey University. Eighty students responded to a questionnaire of which 19 met the case definition, a 24% attack rate. Faecal specimens from seven students contained Cryptosporidium oocysts and Cryptosporidium parvum IIa A18G3R1 was identified from one of the specimens. The inferred median incubation period was five days (range 1–12 days). All of the cases were self-limiting, characterized by diarrhoea, abdominal cramps, and in some cases vomiting, headache, and fever. Having contact with calves with diarrhoea was significantly associated with increased adjusted odds of being a case (OR 10.61, 95% CI 1.87–108.29 for one week of contact; OR 55.05, 95% CI 3.80–1931.18 for two weeks of contact). Outbreaks of cryptosporidiosis had occurred previously among veterinary students at Massey University, but the extremely high infectivity of C. parvum resulted in student illness despite enhanced hygiene precautions.

Veterinary Students Have a Higher Risk of Contracting Cryptosporidiosis when Calves with High Fecal Cryptosporidium Loads Are Used for Fetotomy Exercises

“…Several students emphasized their interest in the exercise, but more than two thirds of the students declared nervousness about becoming sick in relation to the fetotomy exercise, and some students were observed wearing two face masks or four pairs of gloves on top of each other. This is in line with previous conceptions of enteric disease being a "rite of passage" in the veterinary curriculum, while nowadays the level of concern is higher (12). Several measures can be implemented to decrease the risk of cryptosporidiosis among veterinary students (12), including reducing the involvement of veterinary students with animals, which has however been suggested with a remark: "must be balanced with the value of clinical experience in producing practice-ready new graduates" (12).…”

“…Outbreaks of cryptosporidiosis in veterinary students have been widely reported and associated with direct handling of calves during academic training (12)(13)(14)(15)(16)(17). Some of these outbreaks have been linked to fetotomy exercises (14).…”

Study on Giardia duodenalis and <i>Cryptosporidium</i> spp. infection in veterinarians in Poland

“…Because the transmission risk to humans depends on the species or genotype of the parasite, the molecular characteristics of the isolates is necessary for the assessment of epidemiological risk [3]. Using the molecular methods, Benschop et al [12] confirmed that 7 out of 156 veterinary science and veterinary technology students at Massey University in New Zealand were suffering from cryptosporidiosis. All 7 faecal specimens contained Cryptosporidium oocysts, whereas Cryptosporidium parvum IIa A18G3R1 was identified from one of the specimens.…”

“…Much less is known about the risk of giardiasis among veterinarians and other occupational groups exposed to animal carriers. According to NIZP-PZH data, every year in Poland about 1,300 cases of giardiasis are recorded in humans [12], with the risk of giardiasis among children reaching 12.5% [13]. The negative results of diagnostic tests for Cryptosporidium spp.…”

Cysteine proteases in protozoan parasites

“…Outbreaks have been described among caregivers and students of veterinary hospitals after contact with calves infected with C . parvum , the zoonotic species [ 86 ]. A major outbreak was reported in Milwaukee in 1993, in which 403,000 people were infected and the cost of outbreak-associated illness was US$96.2 million [ 87 , 88 ].…”