The Aetiology and Risk Factors for Warts among Poultry Processing Workers

We conducted an investigation at a poultry processing plant in New Zealand to estimate the prevalence of warts among workers and the risk of developing warts associated with specific work areas or individual work practices. We obtained information on demographic characteristics and self-reported medical and occupational histories from 88 (83%) of 106 permanent employees at the plant; almost half (39 people or 44%) had developed wart-like lesions on their arms or hands after they began working at this plant. We also conducted clinical evaluations of 28 of the 32(88%) people with wart-like lesions at the time of the investigation; in all but one case, a diagnosis of warts was confirmed. We collected scrapings of warts from 22 (79%) people and identified human papillomavirus (HPV) type 7, which is reportedly un common in the general public, in 12 of these specimens. People working at the time of their interview in areas where they often handled dead, raw, unfrozen chickens were three times more likely to have developed warts (Odds ratio [OR]=3.0, 95% confidence interval [CI]:1.2–8.0); for those who had ever worked in these ‘high-risk’ areas, this excess risk almost doubled (OR=5.6, 95% CI: 2.1–14.7). Nine of the 12(75%) people with HPV type 7 had worked in these areas at some time. In contrast to previous reports, we found no increased risk of having warts associated with environmental factors or the frequency of cuts and abrasions. Precautions to prevent infection with HPV and to limit spread might include having workers in identified high-risk areas (especially people with wart-like lesions) wear vinyl/rubber gloves, if practical.