Tropical diseases : a manual of the diseases of warm climates / by Sir Patrick Manson.
- Patrick Manson
- Date:
- 1907 (repr. 1912)
Licence: In copyright
Credit: Tropical diseases : a manual of the diseases of warm climates / by Sir Patrick Manson. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
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![Presently it divides into a number of daughter cells and residual bodies. The former produce a vast number-as many as ten thousand m a single oocyst -of minute bodies, the sporozottes (zygotoblasts, terminal rods-Ross). Finally the oocyst ruptures discharging the sporozoites into the body cavity ot the insect, whence they are transferred to the salivary crlands, in the secretion of which, opportunity offering, they are injected into the blood of an appropriate vertebrate, whose blood corpuscles they subsequently enter, and, becoming schizonts, renew the cycle, ihe process of multiplication in this the sexual or exogenous cycle is called sporogony. POSSIBILITY OF YET ANOTHER PHASE So far the story of the life-history of these parasites seems to be complete. There are certam facts, however, which seem to indicate the possibility of yet another phase, or of etiological factors which hitherto have escaped observation. First, there are districts in India, Africa, and elsewhere that are prac- tically uninhabited on account of the prevalence and virulence of the local malaria. If man be necessary for the completion of the life-cycle of the parasite, how explain its abundance in such circumstances— that is to say, in the absence of man? Second, those engaged in malarious districts on works en- tailing disturbance of the soil, e.g. opening jungle lands, digging canals or foundations, making roads or railways, are particularly prone to contract malaria; yet such operations at first sight seem in no way calcu- lated to foster broods of malaria-infected mosquitoes. How account for infection in such circumstances] where, and in what form, is the malaria germ to be found there 1 Of the first of these difficulties two explanations may be submitted, {a) The malaria parasite may be capable of living in a variety of animal hosts, as we know to be the case with the hjemoprotozoa of birds and many other and more highly organised animal parasites. It may be that in the malarious districts alluded to the prevalence of such](https://iiif.wellcomecollection.org/image/b21360352_0055.jp2/full/800%2C/0/default.jpg)
