There are over 1000 species of fleas, small, wingless parasites that live on some animals—dogs, cats, rabbits—and some birds. Fleas will, in the absence of their usual host, feed on man. Some people have specific allergic reactions to their bites; some people also seem to be more attractive to fleas than others! As fleas may be the vectors of typhus, bubonic plague and tularaemia, their control is very much in the interests of public health.

Lice infections are no longer uncommon. Lice may be transmitted to man by animals although this, in fact, happens fairly rarely. Nevertheless, for the purposes of this book, lice will be dealt with in this category. There are three types of louse: head, body and pubic varieties. The wingless female louse lives for about a month, during which it lays several hundred eggs: these are called nits, and are glued to the hair. They hatch in about a week, and are fully grown one week later. They live on blood sucked from the akin. Head lice are most common in children, and are spread chiefly by shared combs, brushes or caps. Itching of the scalp is usually severe with this condition. One per cent gammabenzene hexachloride lotion or malathion, will usually kill the lice. The nits, however, must be combed out with a fine, toothed comb. Body lice are uncommon, except in vagrants. The eggs or nits are laid in clothing, rather than hair. Pubic lice are seen quite often, and may be transmitted via clothing, towels, and sexual intercourse. The main complaint, as with other forms of louse infestation, is severe itching, which is usually followed by infection of the affected area due to scratching. Treatment is best effected with either 1 per cent gammabenzene hexachloride, or D.D.T. powder.

Various mites which infest animals or birds may infect man. These may either cause a severe disease, such as Scrub Typhus which is transmitted by rats, or an allergic response known as papular urticaria. The latter is a common disorder mainly affecting children in the spring and summer months. It is characterized by the development of persistent, extremely itchy lumps. Any biting insect, such as fleas, mosquitos, sand flies, grass mites and bed bugs, may be responsible. Fowl, starling or pigeon mites (dermanyssus gallinae) are common culprits, and these of course may infest other small animals as well as man directly. Consequently dogs, cats, possums and so forth may act as vectors. Commonly, however, humans contract the allergy by handling infected birds, or cleaning their cages, although starving mites, in search of another host after the birds leave the nest, may enter the house through windows, chimneys or ventilators.

Some individuals may be allergic to dogs* or cats’ saliva, and may develop swellings and allergic eczema if licked by these animals. Other allergic manifestations such as asthma and hay fever may also develop. Hypersensitivity amongst humans to bird feathers and eggs is not rare, and may cause asthmatic attacks, hives or hay fever.

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