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      Outbreak of Cryptosporidiosis Among Veterinary Medicine Students — Philadelphia, Pennsylvania, February 2015

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          Abstract

          On February 20, 2015, a northeastern university’s student health center was notified of five veterinary medicine students with gastrointestinal symptoms. An investigation was conducted to establish the existence of an outbreak, determine the etiology, evaluate risk factors, and recommend control measures. All five students had attended a training session at the university’s bovine obstetrics laboratory on February 13, which included the handling of two euthanized calves. Patient symptoms, date of onset, and history of calf exposure suggested cryptosporidiosis. Infection with Cryptosporidium, a protozoa that causes watery diarrhea and is transmitted by infectious oocysts via the fecal-oral route (1), is common among calves (2). Symptoms in humans typically begin 7 days (range = 2–10 days) after infection and include intermittent abdominal cramps, nausea, vomiting, fever, and weight loss, lasting approximately 1–2 weeks (3). Two calves used in the training sessions had been euthanized and frozen at −1.4°F (−17.0°C) on February 11. Approximately 28 hours later, the calves were thawed and detergent-washed by laboratory staff in accordance with standard protocols. Necropsies were performed on both animals on February 23, and revealed Cryptosporidium oocysts on an acid-fast stain of an intestine smear from one of the calves. Interviews revealed that 22 students had attended the training session. Sixteen students reported symptoms, including diarrhea (13 students), abdominal cramps (13), nausea (12), fatigue (eight), vomiting (seven), anorexia (five), headache (four), and chills or sweats (four), lasting 2–10 days. Among the 16 symptomatic students, the median age was 25 years (range = 24–30 years), and 13 were female. Four symptomatic students submitted stool specimens. One case was confirmed by detection of Cryptosporidium oocysts using direct fluorescent antibody testing; the other 15 were classified as probable cases, based on CDC case definitions (1). To account for the possibility of other infectious etiologies, stool specimens were also tested for Giardia, Cyclospora cayetanensis, Isospora, Salmonella, Shigella, Escherichia coli, and Campylobacter; all tests were negative. The positive acid-fast stain from one of the calves and one of the students with a confirmed case implicated the obstetrics laboratory as the source of the outbreak. The bovine obstetrics laboratory personal protective equipment (PPE) protocol includes donning of gloves and coveralls before animal handling and cleaning boots and doffing of gloves and coveralls after animal handling, followed by 30 seconds of hand washing with warm water and soap. Face protection is not included in PPE protocols for this laboratory. Although all of the 22 students wore gloves during the training session, the number of students who removed their coveralls or washed their hands afterwards is unknown. At least four of the symptomatic students reported that they did not immediately doff their coveralls. Cryptosporidiosis outbreaks have been reported among veterinary students (4), usually through contact with infected calves, and are associated with lapses in hygiene (5). In this outbreak, students were infected through contact with euthanized calves that had been frozen and thawed before the training session. Cryptosporidium oocysts can survive various environmental pressures, including extended exposures at temperatures as low as −7.6°F (−22.0°C) for >700 hours (6). This cluster highlights the importance of appropriate hygiene and proper animal cadaver handling. Since the likelihood of calves being infected with cryptosporidiosis is high, veterinary medical institutions should ensure that recommendations for PPE and proper hygiene techniques for students and staff are fully implemented.

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          Most cited references 5

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          Survival of Cryptosporidium parvum oocysts under various environmental pressures.

          The survival of various isolates of Cryptosporidium parvum oocysts under a range of environmental pressures including freezing, desiccation, and water treatment processes and in physical environments commonly associated with oocysts such as feces and various water types was monitored. Oocyst viability was assessed by in vitro excystation and by a viability assay based on the exclusion or inclusion of two fluorogenic vital dyes. Although desiccation was found to be lethal, a small proportion of oocysts were able to withstand exposure to temperatures as low as -22 degrees C. The water treatment processes investigated did not affect the survival of oocysts when pH was corrected. However, contact with lime, ferric sulfate, or alum had a significant impact on oocyst survival if the pH was not corrected. Oocysts demonstrated longevity in all water types investigated, including seawater, and when in contact with feces were considered to develop an enhanced impermeability to small molecules which might increase the robustness of the oocysts when exposed to environmental pressures.
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            Outbreak of cryptosporidiosis among veterinary students.

            In January 2007, six veterinary students became infected with Cryptosporidium species, and records indicated that another student had been diagnosed in November 2006. It was established that the seven students had worked with cattle from the same farm. Microbiological tests indicated that they were infected with Cryptosporidium parvum. Subtyping by sequence analysis indicated a common source of infection for five of the students, but there was insufficient material to type the other two samples. Investigations indicated that the outbreak was caused by a lapse in hygiene, particularly handwashing, on a farm with enzootic C parvum in calves.
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              An outbreak of cryptosporidiosis among veterinary science students who work with calves.

              The authors describe an outbreak of cryptosporidiosis among students working with calves as part of their veterinary science technology program. After an off-campus provider identified an index case, school authorities requested cryptosporidium (crypto) as part of the stool ova and parasite examination of all students presenting to the college health center with significant gastroenteritis. Thirteen students submitted stool specimens that were examined for crypto; 7 were positive, and all were from veterinary science students. One of the calves used in the program also tested positive for crypto. All of the students were immunocompetent and recovered uneventfully. The outbreak was contained by strictly enforcing infectious-disease precautions in the calf barn. The authors recommend considering crypto as a cause of gastroenteritis, especially among farm-animal workers, and urge strict infectious disease precautions for those who attend to livestock.
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                Author and article information

                Journal
                MMWR Morb Mortal Wkly Rep
                MMWR Morb. Mortal. Wkly. Rep
                MMWR
                MMWR. Morbidity and Mortality Weekly Report
                U.S. Centers for Disease Control
                0149-2195
                1545-861X
                24 July 2015
                24 July 2015
                : 64
                : 28
                : 773
                Affiliations
                [1 ]University of Pennsylvania
                Author notes
                Corresponding author: Lauren N. Drinkard, drinkard@ 123456upenn.edu , 215-746-0806.
                Article
                773
                4584865
                26203633

                All material in the MMWR Series is in the public domain and may be used and reprinted without permission; citation as to source, however, is appreciated.

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                Notes from the Field

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