CDC Epidemic Intelligence Service Shares Recent Zoonotic Disease Research

Zoonotic diseases caused by viruses, bacteria, parasites, and fungi that are spread between animals and humans are quite common and scientists estimate that more than 60% of human infectious diseases are spread from animals, according to the Centers for Disease Control and Prevention (CDC).

Officers of the CDC’s Epidemic Intelligence Service (EIS) presented the results of their recent research on May 4 in the Zoonotic Diseases session of the 65th Annual Epidemic Intelligence Service (EIS) Conference in Atlanta, Georgia. A brief summary of the information that was presented is included below:

“Escherichia coli O157 infections cause approximately 95,000 illnesses and 60 deaths yearly in the United States,” Kathryn G. Curran, PhD, said in her talk.

Dr. Curran and her colleagues linked a 2015 Escherichia coli (E. coli) O157 infection outbreak in Whatcom County, Washington, to a dairy event for students in a barn contaminated during earlier animal exhibitions. Overall, 60 people became ill, 11 (18%) were hospitalized, and six (10%) developed hemolytic uremic syndrome.

The researchers conducted a case-control study of 27 patients who had laboratory-confirmed E. coli O157 infection, bloody or loose stools, or hemolytic uremic syndrome, and 88 healthy controls. Handwashing with soap and water or hand sanitizer before lunch was protective (odds ratio, 0.29; 95% confidence interval, 0.09 to 0.91). Barn samples yielded E. coli O157 with pulsed-field gel electrophoresis (PFGE) patterns identical to those from outbreak strains. Improper cleaning and the layout of the event may have increased infection risk. The researchers advised better education, handwashing, and other infection control measures.

Alexia Harrist, MD, PhD, and her group studied Francisella tularensis exposure among National Park Service employees at Devils Tower National Monument, Wyoming in 2015. The researchers identified F. tularensis-infected rodents in the park and an employee developed tularemia. None of the employees wore masks or insect/tick repellent whenever they landscaped, and the researchers found no association between protective measure use and seropositivity.

Overall 23 (52%) of employees completed a questionnaire and serosurvey. The results showed that 3 (13%) employees who were seropositive reported contact with a median of 30 ticks, compared with 6 ticks among those who were seronegative (P=0.008). More seropositive employees than seronegative employees used powered blowers (67% versus 5%, P=0.034) and collected animal carcasses (100% versus 30%, P=0.047), respectively. Dr. Harrist advised that individuals who work outdoors can lower their tularemia risk by consistently preventing exposure during F. tularensis epizootics.

Kelly J. Gambino-Shirley, DVM, MPH, and her co-authors found that small turtles remain a source for human Salmonella infections, especially among young children, but that transient turtle vendors may make traceback to the farms they come from difficult. In 2015, the CDC received a consumer complaint of Salmonella Sandiego (SS) transmitted to a child from a small turtle.

Researchers identified 125 cases from 22 states. Of these, 34 (27%) were under 1 year of age and 40 (75%) of 53 patients with ethnicity information were Hispanic. Of 74 patients interviewed, 41 (55%) had been exposed to turtles bought from stores, street vendors, flea markets, or as carnival prizes or gifts. Seven environmental samples matched outbreak strains, and traceback for one patient’s turtle identified a farm with Salmonella-contaminated water, but the outbreak strains were not identified. Zoonotic Salmonella transmission causes an estimated 11% of salmonellosis in the United States, and the researchers advised that prevention messages be translated into the languages of people at high risk.

Ashley R. Styczynski, MD, MPH, found the first confirmation of emerging zoonotic vaccinia in South America outside Brazil. In early 2014, Colombian health authorities contacted CDC about suspected poxvirus infections in farmworkers and dairy cattle, and the agencies collaborated to confirm vaccinia virus as the cause.

Interviews discovered 5 workers and 15 cows at 8 farms with a history of vaccinia-like lesions. Of the 17 human serum samples collected, 10 had anti-orthopoxvirus IgM and 15 had anti-orthopoxvirus IgG. Of 6 skin lesion specimens tested by polymerase chain reaction, 3 were positive, 1 was inconclusive, and 2 were negative. A vaccinia virus strain closely related to a phylogenetic group of strains in Brazil was identified. Due to the risk of inter-human spread in communities and healthcare settings and the impact on agriculture, she advised heightened surveillance, risk factor assessments, and identification of potential animal reservoirs to help prevention and control.

Misha P. Robyn, DVM, and her colleagues found that live cell therapy ‒ the alternative medicine technique of injecting animal cells into humans ‒ was the likely source of a Q fever outbreak in 2014 in the US and Canada among people who had traveled to Germany several months earlier to be injected with sheep cells, a treatment unavailable in the United States.

In fall 2014, five residents in New York State and one in Canada who tested seropositive for the bacterium that causes Q fever, Coxiella burnetii, had Q fever-like symptoms and had traveled to Germany in the spring for live cell therapy by the same physician. German authorities identified a Q fever-positive sheep flock as the source of the cells.

Patients with Q fever had at least one IgG titer 1:128 or higher to C. burnetii phase II antigen. The median patient age was 61 and three (60%) were female. Signs and symptoms began roughly 1 to 7 days after exposure and lasted around 10 to 90 days; 80% of patients reported fever, sweating and fatigue, and 60% reported headache, chills and malaise. No one was hospitalized and no additional cases were identified. The researchers cautioned clinicians to be aware of this practice and to consider zoonotic disease potential in patients receiving live cell therapy.

Lorraine L. Janeczko, MPH, is a medical science writer who creates news, continuing medical education and feature content in a wide range of specialties for clinicians, researchers and other readers. She has completed a Master of Public Health degree through the Department of Epidemiology of the Johns Hopkins Bloomberg School of Public Health and a Dana Postdoctoral Fellowship in Preventive Public Health Ophthalmology from the Wilmer Eye Institute, the Johns Hopkins University School of Medicine and the Bloomberg School.

SOURCE: EIS 2016 Conference Program, pp 69-71: Concurrent Session H1: Zoonotic Diseases

Studies Presented:

Kathryn G. Curran, PhD, EIS officer, Office of Infectious Diseases, Escherichia coli O157 Infections Linked to Dairy Education Event Attendance — Whatcom County, Washington, 2015

Alexia Harrist, MD, PhD, EIS officer, Office of Public Health Scientific Services, Francisella tularensis Exposure Among National Park Service Employees — Devils Tower National Monument, Wyoming, 2015

Kelly J. Gambino-Shirley, DVM, MPH, EIS officer, National Center for Emerging and Zoonotic Infectious Diseases, Multistate Outbreaks of Salmonella Sandiego and Salmonella Poona Infections Linked to Small Turtles — United States, 2015

Ashley R. Styczynski, MD, MPH, EIS officer, National Center for Emerging and Zoonotic Infectious Diseases, Investigation of an Emerging Zoonotic Vaccinia Virus — Colombia, 2015

Misha P. Robyn, DVM, EIS officer, Division of Scientific Education and Professional Development, Epidemiology Workforce Branch, Q Fever Outbreak Among Travelers to Germany Who Received Live Cell Therapy — United States and Canada, 2014