Toxocara infections and kennel workers.

SIR,-It is now widely recognised that the embryonated ova of the common roundworm of the dog, Toxocara canis, are infective for man. Surveys have shown that approximately 2`, of normal healthy adults in the UK possess demonstrable antibodies to toxocara antigen and in certain circumstances infection can produce clinical disease.1 2 Borg and Woodruff3 reported that 24 4°0 of 800 soil samples from public places all over Britain contained Toxocara spp eggs, but still heavier contamination may be found in special situations such as, for example, some breeding kennels and dog training schools.4 One such location was identified during a recent study of the helminth parasites of greyhounds.5 The establishment in question consists of a central complex of buildings, including administrative offices and residential quarters for dog handlers. These are surrounded by kennels and 56 hectares (140 acres) of exercising paddocks and walks. More than 500 adult greyhounds are kept for racing and 12 5`0 of these carry patent T canis infection-that is, about 19m eggs are deposited on the estate each day. Examination of 10 g of soil taken from each of 12 sites on the estate revealed the presence of T canis ova in 11, with up to 18 eggs per sample. In addition, grass collections from small exercising paddocks yielded up to 828 ova per kg of foliage, although only 0 70, of these were embyronated. It was considered that this high degree of contamination might present a potential health hazard to the 70 employees working at the kennels, particularly as the majority also live on the estate. An attempt was therefore made to evaluate the degree of risk involved. Serum was collected from 34 volunteers and examined by a fluorescent antibody test using a T canis larval antigen.' It was found that none of the 24 people who had worked at the kennels for between 6 months and 10 years showed evidence of infection (see table ), but two workers with 22 and 43 years' service respectively had positive antibody titres. A further two long-term employees were, however, negative. Although no general conclusions can be drawn from this one small study the results suggest that, at least in this instance, infection with T canis is not readily acquired by kennel