Flics and disease

In the context of these books, "Flies" virtually means cyclorrhaphous Diptera, a fascinating and evolutionarily highly successful group of insects. There are, for example, more of these species in Britain than all other exopterygote insects together. A considerable number of these flies have developed various relationships with higher vertebrates, including man and his domestic animals. The larval stages may feed on animal faeces (or decaying vegetation enriched with excreta), or in cadavers, or in wounds and sores, or they may pierce skin and breed in flesh. The adults may merely take advantage of human shelters and feed on man's foodstuffs, or may feed on bodily exudations (sweat, conjunc-tival fluid) or on blood. Flies with any of these associations with man are described as synanthropic; and many of them take part in transmission of various pathogens. Unlike the sole and specific disease vectors of such diseases as malaria, flies are only one of several modes of transmission in these cases. It is by no means easy to assess the relative importance of " fingers, faeces, food and flies " in the carriage of some important enteric and ophthalmic infections. The subject was discussed as long ago as 1913 [Flies in relation to disease, Trop. Dis. Bull., 1913, v. 2, 655] by GRAHAM-SMITH. The preeminent role of house-flies was also considered in an excellent book by C. G. HEWITT (Houseflies and how they spread disease, Cambridge Univ. Press, 1914) and a more recent one by WEST [Trop. Dis. Bull., 1952, v. 49, 735]. The present pair of books is the most complete and up-to-date account which could be desired. They do not, however, deal with myiasis, nor very extensively with the biology of the house-fly, on the grounds that these subjects are adequately covered respectively by ZUMPT'S Myiasis in man and animals in the Old World [ibid., 1965. v. 62, 483] and WEST'S The housefly [loc. cit.].
Volume II, which is exclusively written by Green-berg, is decidedly more readable. It begins with a short entertaining chapter on flies in history. Then there follow the accounts of fly biology and distribution, to which I have referred. In a competent chapter on flies as hosts of micro-organisms the author discusses the survival and transmission of such organisms in relation to fly anatomy and physiology. The final section of 188 pages (before the bibliography and index) considers, one by one. those diseases of man and domestic animals which flies may transmit. I think Greenberg may justly claim to have reached a sane and balanced evalua-tion of the evidence. His own researches on the subject have, no doubt, helped.
Individual medical entomologists will perhaps be inclined to buy only Volume II, which is fairiy complete in itself; but all departments concerned with public health entomology will certainly require both volumes. J. R. Busvine.