Further preliminary reports on flies as carriers of infection.

Date:
1909
Catalogue details

Licence: In copyright

Credit: Further preliminary reports on flies as carriers of infection. Source: Wellcome Collection.

    31/46 (page 29)
    because it produces blood-red colonies upon the substances on which it grows. The miracle of “ the bleeding host ” in the middle ages has been attributed by modern writers to the development of prodigiosus colonies upon the wafers in damp churches. Because of the characteristic pigment which it produces, B. prodigiosus has been a favourite organism in experimental work. Thus, as early as 1875, Otto Helm (cited by Abel, 1899, p. 1,068) experimented with “ Monas prodigiosa” and stated that the slimy masses contain- ing the bacillus are easily conveyed by flies from one food substance to another. Hart & Smith (1898) cite an experiment by Burgess in which flies were fed on material containing the bacillus and then allowed to fly into a large room. After a few hours the flies were recaptured, and made to walk over slices of sterilized potato on which colonies of prodigiosus subsequently formed. Abel (1899, p. 1,068), quite independently, carried out a similar experiment. He placed cultures of the bacillus and clean potatoes in diflTerent parts of a room. To the latter he added some putrid meat so that the odour should attract the flies. After 2-3 days colonies of prodigiosus appeared on all the potatoes. This did not occur when the room was rid of flies. Abel records two instances in which he observed spontaneous prodigiosus infection of food in houses where flies were numerous. He collected flies in both houses, and placed the captured flies singly in tubes containing sterile potato. Of the 28 flies captured in one house seven gave a positive culture; of 33 flies captured in the other house three gave a positive culture. Abel justly argues that flies may convey the bacilli of ^typhoid and cholera in a similar manner. ScHEURLEN (1896, p. 17 €t seq.) cites 16 recorded cases of “pro- digiosus outbreaks.” In all cases the outbreaks occurred in July, August and September. Abel points out that the outbreaks appear to follow the same rule as typhoid and cholera epidemics. Musca domestica as a carrier of moulds. It is upwards of 20 years since one of us (N.) observed that flies may carry moulds upon their bodies ; this was seen in a paste pot into which flies had fallen and had died. Colonies of Pencillium developed about several of the flies which had become stuck to the paste. More recently. Gay on (1903), has cultivated various species of moidd from flies which he captured and dropped into nutrient gelatin. CONCLUSIONS. During the decade which has elapsed since the appearance of the monograph by Nuttall, the interest in the subject of the relation of arthropods in the dissemination of disease has grown steadily. Hygienists the world over have learnt to appreciate the importance of insects as disease carriers in consequence, more especially, of the brilliant discoveries relating to the part played by mosquitoes in the propagation of malaria and yellow fever, by fleas in the spread of plague, by biting-flies and ticks in the spread of various human and animal diseases.