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The Aethiopian region
286
CORRESPONDENCE
MORPHOLOGY OF THE PARASITIZED ERYTHROCYTE IN INFECTIONS WITH Plasmodium
ovale.
SIR,--I have read with m u c h interest the remarks of Garnham et al., Transactions (1955) 49, 158, on the morphology of red cells infected with P. ovale : - " O b s e r v a t i o n s o n f r e s h b l o o d revealed no oval i n f e c t e d ceils, t h o u g h s o m e m a m m i l a t i o n of t h e h o s t cell w a s seen. O f t w o t h i n s t a i n e d s m e a r s m a d e s i m u l t a n e o u s l y f r o m t h e s a m e p a t i e n t , o n e s h o w e d
80 per cent. of the infected ceils to be oval while the other showed only 10 per cent. to be of this form. In general, oval infected cells were not very common and fimbriation was rare. The obvious conclusion is that both the oval shape and the fimbriation of the host cells are artefacts occurring in dry fixed thin smears, but we do not suggest that this conclusion lessens the diagnostic value of the artefact " (p. 161). Some unfinished observations interrupted by the outbreak of the last war support these conclusions. T h e following remarks are taken from notes made at that time. Examinations of fresh coverslip-slide preparations were made at times when thin stained smears from ovale infections showed numerous oval and fimbriated cells. (a) Infected cells did not show oval outlines nor was mammilation present, except when the adjacent normal cells also showed some spiculation. ( T h e former cells appeared brassy as compared with the coppery hue of the latter). (b) W h e n the coverslip was disturbed it was seen that the infected cells were not discoid like normal erythrocytes, but were globular in shape. (c) Where the blood layer was one cell thick, pressure caused the red cells to stream across the microscope field. In these conditions, the infected cells appeared to adhere to the slide (or coverslip) and to become distorted into oval, tailed and fimbriated forms. W h e n the movement ceased these forms took an appreciable time to return in statu quo ante but did so relatively quickly. (d) When small rouleaux were formed, these seldom contained parasitized cells. T h e latter appeared to lie free mainly in the intermediate spaces. It looked as if the " sticky " nature of the infected cells prevented them from joining the rouleaux when these were being formed (or perhaps such cells have a different electrical charge). These findings support the view that the distortion of the infected erythrocytes in ovale infections is artificial and is not a normal morphological characteristic of such cells in vivo. Such a view is supported by other observations : - (e) T h e r e are very considerable variations in the proportion of distorted cells in different dry smears made at the same time. (f) Such cells frequently lie with their long axes parallel, which would not be expected under natural conditions. (g) T h e y occur most frequently in the thin parts of such smears and are rarely or never seen in the thicker portions. T h e explanation of this p h e n o m e n o n appears to be that, at a certain stage of the development of the parasite, the physical properties of the infected cells become such that they are liable to distortion when smears are made. On account of their changed physical condition, they do not return so quickly in statu quo ante as do normal red cells, and so, in thin portions of the smear which dry most rapidly, they are fixed in their changed shape. In the slowerdrying, thicker parts of the film they have time to revert to the shape they had in vivo. Whether this distortion owes its origin mainly to the globular shape of the infected cell, to its adhesive character, or to both factors, has not been determined. T h e fact that the points of the fimbriae often show a dot of stippling suggests that this may possibly be associated with the adhesive property.
CORRESPONDI}NCE
287
It seems to be, therefore, that such apparent change in the morphology of the infected cell at certain stages in ovale infections, is not a true morphological feature of such cells in vivo but only" an indication of a changed physical state of these cells. This happens to be demonstrated by the method in which the blood examination is usually made. An almost identical distortion of parasitized cells is reported by Sinton and Mulligan (1932, 1933) in infections of monkeys with P. hnowlesi. This is probably due to like causes. The banded forms of parasite seen at certain stages of infections with P. inui and with P. malariae also appear to be artefacts produced in a similar manner (Sinton, 1935). In these instances, however, it is the special physical condition of the parasite, and not of the red cell, which is responsible for the morphological change produced by the method of preparation for examination. Although artificially produced all these distortions are still o f great diagnostic value.
Slaghtfreedan Lodge, Cookstown, N. Ireland. 18th April, 1955.
I am, etc., J. A. SINTON.
REFERENCES. SINTON, J. A. (1935). Rec. Malar. Surv. India, 4, 404. - • MULLIGAN, H. W. (1932). Ibid., 3, 357.
- -
&- -
(1933). Ibid., 3, 381.
" CAUSAL ORGANISMS OF MADUROMYCOSIS" SIR,--I have read the letter by P. H. Abbott (Transactions, 49, 195) referring to my paper " A Contribution to the Study of the Causal Organisms of Maduromycosis " (Transactions, 48, 470). After I sent the manuscript of my paper to be published in the Transdctions, Dr. Dante Borelli, from Caracas-Venezuela, continued in our laboratory in Montevideo some studies on Madurella mycetorni ; he observed on slide cultures on corn meal agar, after 1 month at 26°C, aleuriospores similar to those described by Abbott in his most interesting thesis, and by Chalmers and Archibald in Glenospora khartoumensis. The identity between M. mycetomi and G. khartoumensis becomes even more evident. It seems to me useful to profit by this opportunity to announce that in a case of mycetoma by J~¢/. mycetomi, I observed sclerotia-like grains. Like the sclerotia observed in cultures, these grains did not show an interstitial substance. Nevertheless, they cannot be confused with the grains of other species producing mycetoma, and, moreover, they coexist with the typical grains already described. I am, etc., London School of Hygiene and Tropical Medicine, 25th April, 1955.
JUANE. MACKINNON.
CORRESPONDENCE
MORPHOLOGY OF THE PARASITIZED ERYTHROCYTE IN INFECTIONS WITH Plasmodium
ovale.
SIR,--I have read with m u c h interest the remarks of Garnham et al., Transactions (1955) 49, 158, on the morphology of red cells infected with P. ovale : - " O b s e r v a t i o n s o n f r e s h b l o o d revealed no oval i n f e c t e d ceils, t h o u g h s o m e m a m m i l a t i o n of t h e h o s t cell w a s seen. O f t w o t h i n s t a i n e d s m e a r s m a d e s i m u l t a n e o u s l y f r o m t h e s a m e p a t i e n t , o n e s h o w e d
80 per cent. of the infected ceils to be oval while the other showed only 10 per cent. to be of this form. In general, oval infected cells were not very common and fimbriation was rare. The obvious conclusion is that both the oval shape and the fimbriation of the host cells are artefacts occurring in dry fixed thin smears, but we do not suggest that this conclusion lessens the diagnostic value of the artefact " (p. 161). Some unfinished observations interrupted by the outbreak of the last war support these conclusions. T h e following remarks are taken from notes made at that time. Examinations of fresh coverslip-slide preparations were made at times when thin stained smears from ovale infections showed numerous oval and fimbriated cells. (a) Infected cells did not show oval outlines nor was mammilation present, except when the adjacent normal cells also showed some spiculation. ( T h e former cells appeared brassy as compared with the coppery hue of the latter). (b) W h e n the coverslip was disturbed it was seen that the infected cells were not discoid like normal erythrocytes, but were globular in shape. (c) Where the blood layer was one cell thick, pressure caused the red cells to stream across the microscope field. In these conditions, the infected cells appeared to adhere to the slide (or coverslip) and to become distorted into oval, tailed and fimbriated forms. W h e n the movement ceased these forms took an appreciable time to return in statu quo ante but did so relatively quickly. (d) When small rouleaux were formed, these seldom contained parasitized cells. T h e latter appeared to lie free mainly in the intermediate spaces. It looked as if the " sticky " nature of the infected cells prevented them from joining the rouleaux when these were being formed (or perhaps such cells have a different electrical charge). These findings support the view that the distortion of the infected erythrocytes in ovale infections is artificial and is not a normal morphological characteristic of such cells in vivo. Such a view is supported by other observations : - (e) T h e r e are very considerable variations in the proportion of distorted cells in different dry smears made at the same time. (f) Such cells frequently lie with their long axes parallel, which would not be expected under natural conditions. (g) T h e y occur most frequently in the thin parts of such smears and are rarely or never seen in the thicker portions. T h e explanation of this p h e n o m e n o n appears to be that, at a certain stage of the development of the parasite, the physical properties of the infected cells become such that they are liable to distortion when smears are made. On account of their changed physical condition, they do not return so quickly in statu quo ante as do normal red cells, and so, in thin portions of the smear which dry most rapidly, they are fixed in their changed shape. In the slowerdrying, thicker parts of the film they have time to revert to the shape they had in vivo. Whether this distortion owes its origin mainly to the globular shape of the infected cell, to its adhesive character, or to both factors, has not been determined. T h e fact that the points of the fimbriae often show a dot of stippling suggests that this may possibly be associated with the adhesive property.
CORRESPONDI}NCE
287
It seems to be, therefore, that such apparent change in the morphology of the infected cell at certain stages in ovale infections, is not a true morphological feature of such cells in vivo but only" an indication of a changed physical state of these cells. This happens to be demonstrated by the method in which the blood examination is usually made. An almost identical distortion of parasitized cells is reported by Sinton and Mulligan (1932, 1933) in infections of monkeys with P. hnowlesi. This is probably due to like causes. The banded forms of parasite seen at certain stages of infections with P. inui and with P. malariae also appear to be artefacts produced in a similar manner (Sinton, 1935). In these instances, however, it is the special physical condition of the parasite, and not of the red cell, which is responsible for the morphological change produced by the method of preparation for examination. Although artificially produced all these distortions are still o f great diagnostic value.
Slaghtfreedan Lodge, Cookstown, N. Ireland. 18th April, 1955.
I am, etc., J. A. SINTON.
REFERENCES. SINTON, J. A. (1935). Rec. Malar. Surv. India, 4, 404. - • MULLIGAN, H. W. (1932). Ibid., 3, 357.
- -
&- -
(1933). Ibid., 3, 381.
" CAUSAL ORGANISMS OF MADUROMYCOSIS" SIR,--I have read the letter by P. H. Abbott (Transactions, 49, 195) referring to my paper " A Contribution to the Study of the Causal Organisms of Maduromycosis " (Transactions, 48, 470). After I sent the manuscript of my paper to be published in the Transdctions, Dr. Dante Borelli, from Caracas-Venezuela, continued in our laboratory in Montevideo some studies on Madurella mycetorni ; he observed on slide cultures on corn meal agar, after 1 month at 26°C, aleuriospores similar to those described by Abbott in his most interesting thesis, and by Chalmers and Archibald in Glenospora khartoumensis. The identity between M. mycetomi and G. khartoumensis becomes even more evident. It seems to me useful to profit by this opportunity to announce that in a case of mycetoma by J~¢/. mycetomi, I observed sclerotia-like grains. Like the sclerotia observed in cultures, these grains did not show an interstitial substance. Nevertheless, they cannot be confused with the grains of other species producing mycetoma, and, moreover, they coexist with the typical grains already described. I am, etc., London School of Hygiene and Tropical Medicine, 25th April, 1955.
JUANE. MACKINNON.