Observations on dust mites (Acari: Pyroglyphidae) in coastal hospitals in South Africa

Abstract

Surveys of houses in South Africa have shown that dust mites and mite-derived antigens are more common along the eastern and southern coastal lowlands than on the central Highveld plateau. The present study extended this research to hospitals in the three major coastal cities; to determine whether or not dust mites were present in ward furnishings and on floors; and if so; at what densities. Sampling; over 22 months; in provincial and private hospitals in Durban; Port Elizabeth and Cape Town recovered 10 mite species; including the cosmopolitan pyroglyphids; Dermatophagoides farinae; D. pteronyssinus; Euroglyphus maynei and Malayoglyphus intermedius. Mites were found in all sampled habitats without any apparent preferences; but mean densities were mostly below 10/m2; lower than found previously in houses along the coast. To characterise mite habitats in these coastal hospitals; preliminary environmental data were collected in wards and from inside mattresses. These showed nearly constant environments; with moderate temperatures and relative humidity and narrow annual ranges. Temperature and relative humidity levels decreased with increasing latitude from Durban to Cape Town.