Zoo data show low incidence of animal–human infection

By Sarah Guy, medwireNews Reporter

Zoonotic transmission rates are low and the risk for animal-human infection is well managed, show zoo data spanning 19 years.

"Ongoing assessment of risk factors is needed as environmental, human and animal disease and management factors change," suggest Craig Pritchard (New Zealand Centre for Conservation, Auckland, New Zealand).

A total of 49, 42, and 46 zoo staff participated in the 1991, 2002, and 2010 surveys conducted by Pritchard et al, including questions on animal exposure and illness compatible with a range of zoonotic infections.

Participants also underwent serologic testing for infections including hepatitis A virus (HAV), Toxoplasma gondii, and Chlamydophila psittaci, as well as feces testing, skin sample examination, and Mantoux (in 2010, the QuantiFERON-TB Gold In-tube test) testing for tuberculosis.

The cohort comprised animal handlers, veterinary clinic staff, grounds, horticulture, and maintenance staff, and public education, office, and support staff, who, in the 2010 survey, had been employed at the zoo for a median of 5 years.

The majority of staff (80%) had domestic animals at home, including dogs, cats, birds, fish, turtles, and poultry.

In all, 16 staff from the 2010 survey reported 18 work-related conditions or exposures over the preceding 5 years including skin allergies from specific species and/or chemicals. One participant had a dermatophyte infection (Microsporum gypseum) and one reported Erysipelothrix rhusiopathiae infection following trauma to a finger while at work.

Two veterinary clinic staff may have been exposed to C. psittaci in the months before the 2010 survey, when carrying out post-mortem examinations on infected feral doves. However, the serologic results only indicated low-level antibodies at the time of the survey in one individual, and seronegativity in the other.

Presence of HAV antibodies was similar in 2002 and 2010 results, at 46%. However, in 2010, nine of the 21 staff with antibodies had a history of vaccination, and one had HAV infection unrelated to work, with the remaining number of seropositive results similar to that found in the general population, remark the researchers.

None of the staff was hepatitis B virus (HBV) positive, and feces testing revealed no human cases of Shigella, Yersinia, Salmonella, or Campylobacter infections despite known instances of the latter two at the zoo in the previous 5 years.

"Policies and procedures should be reviewed periodically in conjunction with disease monitoring results for both animals and staff," conclude Pritchard and team in Zoonoses and Public Health.

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