The epidemiology of bite and scratch injuries by vertebrate animals in Switzerland

Pet and wildlife populations are a potential source of various public health problems, and injuries and complications due to animal bites and scratches are the most obvious. As no population based data on the frequency of animal bites were available at a national level in Switzerland, a study was conducted by the Swiss Sentinel Surveillance Network. The objectives of this study were to estimate the incidence of medical consultations due to bite and scratch injuries in humans caused by vertebrate animals, to identify possible risk factors, and to assess bite management habits in primary health care. An annual bite and scratch incidence rate of 325 per 100,000 population was estimated. Consultations peaked during the summer months and geographical differences in the reported incidence were observed. Dogs accounted for more than 60% and cats for about 25% of all cases reported. Animal bites and scratches were frequent in persons under 20 years of age. In most ages, the incidence was higher among women than among men, but not in children under the age of ten years. The incidence of cat bites was especially high in adult women. Bites to the head and neck were most frequent in infants and young children and accounted for approximately one third of the reported cases in this age group. Patients sought medical care principally for primary wound care (52.0%) and for vaccination advice (29.6%). Rabies postexposure prophylaxis was initiated in 1.1% of patients. Wound infection was reported in 10.9% of cases, with cat bites/scratches being more often infected than injuries due to dogs. Hospitalization was reported in 0.3 % of patients. Data from the emergency department of two district hospitals showed that head and neck injuries were more frequent in out-patients and a higher proportion of persons presented with wound infections (14.1%). The hospitalization rate for emergency department visits was 4.7%. Animal bites and scratches are common events in Switzerland. They represent a public health issue of growing importance due to the steadily increasing pet population. A practice based sentinel surveillance system may be an appropriate tool to monitor national trends in animal bites and scratches.