The development of Plasmodium gallinaceum from sporozoite to erythrocytic trophozoite / Clay G. Huff and Frederick Coulston.

  • Huff, Clay G., 1900-
Date:
1944
Catalogue details

Licence: Public Domain Mark

Credit: The development of Plasmodium gallinaceum from sporozoite to erythrocytic trophozoite / Clay G. Huff and Frederick Coulston. Source: Wellcome Collection.

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    time of the discovery of the sporogonous development in the mosquito. One of these was the obvious assumption that the sporozoite entered directly into the red blood cell and initiated the parasit- emia; the other held that some inter- mediate development occurred between the injection of the sporozoite into the vertebrate host and the beginning of the attack on the erythrocytes. Grassi (1899) sponsored the latter view be- cause he believed the nuclear differences between sporozoites and the young trophozoites were too great to accord with the theory of the direct entry of sporozoites into erythrocytes. However, the lucid description by Schaudinn (1902) of his observation of the direct entry of the sporozoite into erythrocytes which was accompanied by convincing drawings practically removed the ques- tion from the realm of theory and es- tablished the direct-entry conception in the minds of most malariologists as an established fact. After 20 years there began a period of accumulation of evi- dence, much of it of an indirect nature, against the validity of this view. This evidence falls into the 4 categories: (1) the inefficacy of chemoprophylaxis, (2) failure of attempts to repeat Schau- dinn’s observations, (3) the existence of a period of non-infectivity of the blood and of the infectivity of certain organs following both mosquito bite and in- jection of sporozoites, and (4) the exist- ence of exoerythrocytic stages in the life cycles of certain species of malarial parasites. In 1922 the Sergent brothers showed that quinine injected in large doses on the day that canaries were bitten by Culex mosquitoes infected with P. re- lictum, did not prevent infection in the bitten birds. Yorke and MacFie (1924) in their studies on P. vivax infections in general paretics, observed a similar difference in the efficacy of quinine in preventing infections induced by blood inoculation on the one hand and those induced by sporozoites on the other. Similar observations by James (1931) led him to discard the prevalent view that sporozoites enter erythrocytes di- rectly and to establish the theory that there exists a tissue stage intermediate between the sporozoite and the erythro- cytic stages. The observations of. the Sergents, Yorke and Mackie, and James upon the inefficacy of the antimalarial drugs were confirmed and extended to other species of malarial parasites by many others including Swellengrebel and de Buck (1931), Russell and Nono (1932), Kikuth and Giovannola BERLIE and Missiroli (1937). Numerous investigators have tried in vain to observe the direct penetration of sporozoites of various species of ma- larial parasites into the erythrocytes of susceptible hosts. These include Yorke and MacFie (1924), Yorke (1931), Boyd and Stratman-Thomas (1934), and Raffaele (1934). On basis of the many negative experiments done in this laboratory beginning in 1930 by Huff, by Gingrich and by Stauber which were not published, it is our opinion that many other unpublished attempts to confirm Schaudinn’s observations have been made. It is known that by increasing the number of erythrocytic parasites in the inoculum the incubation period may be > decreased in length to the point of its complete disappearance. By contrast, tain minimum “negative phase”’ exists during which the blood is noninfectious when subinoculated to susceptible hosts. (Boyd. and Stratman-Thomas, 1934; Raffaele, 1936; 1937; Warren and Cog- geshall, 1937; Ciuca et al., 1937; Mis- siroli, 1937; Kikuth and Mudrow, 1938; Henry, 1939; Boyd and Matthews, 1939). In spite of this period of non-
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