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Abnormal forms of Plasmodium vivax
97 TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENF.
Vol. 43. No. 1. July, 1049.
CORRESPONDENCE.
ABNORMAL
FORMS
OF PLASMODIUM
VIVAX
To the Editor, TRANSACTIONSof the Royal Society of Tropical Medicine and Hygiene. SIR,
We have only recently had an opportunity of reading Dr. J. W. FIELD'S paper on Morphological Variation in Plasmodium vivax which appeared in Parasitology 34, 82, and was reviewed in The Tropical Diseases Bulletin, 40, 7. This account of abnormal forms of P. vivax interested us very much, as the parasite descriptions resemble in some points parasite infestations that we observed in three cases infected in the Moshi district in 1937. We, unfortunately, had no clinical notes on the cases as they had already commenced treatment at the time of examination of the blood films, but, morphologically, they resembled those described by ROBERTS(1941), and named P. wilsoni. East African Med. Journal, 17, 215. The points of resemblance between them, made at the time from notes and camera lucida drawings, and those described by Dr. FIELD are: (1) Multiple invasion of single red cells with up to four parasites. (2) Distortion of the host cell (many were quite astonishingly distorted). (3) Compactness of the smaller parasites. (4) Closely packed schizonts. (5) Resemblance of parasites to P. malariae except for their presence in enlarged cells. The points of difference are as follows : (1) The corpuscle was always enlarged, sometimes very greatly so, and paler than normal. (2) Stippling of the cell either absent, or if present, of a faint P. malariae type, or trabeculation of the cell. (3) Parasites occasionally seen which were separated from the corpuscles in which they had grown. G
98
CORRESPONDENCE
(4) The multiple parasites in single cells were practically never vacuolated rings, but were of varied form and size. The chromatin often appeared separate from the cytoplasm, and in some cases the impression received by the eye was that of various little pieces of chromatin and cytoplasm dotted about the greatly enlarged cell. It is probable that the parasites describedby ROBERTS(1941) were abnormal fi)rms of P. vivax, but whether the original parasites we observed in 1937, and demonstrated at a meeting of this Society in 1938, were also abnormal forms of P. vivax, is more doubtful. We continue to hope to encounter them again, and have the opportunity of making repeated examinations and parasite drawings, together with a complete clinical history. l am, etc., MARGARET
MMariaLaboratory, Muheza, Tanganyika Territory, East Africa.
WILSON, M.B., D.T.M.
Vol. 43. No. 1. July, 1049.
CORRESPONDENCE.
ABNORMAL
FORMS
OF PLASMODIUM
VIVAX
To the Editor, TRANSACTIONSof the Royal Society of Tropical Medicine and Hygiene. SIR,
We have only recently had an opportunity of reading Dr. J. W. FIELD'S paper on Morphological Variation in Plasmodium vivax which appeared in Parasitology 34, 82, and was reviewed in The Tropical Diseases Bulletin, 40, 7. This account of abnormal forms of P. vivax interested us very much, as the parasite descriptions resemble in some points parasite infestations that we observed in three cases infected in the Moshi district in 1937. We, unfortunately, had no clinical notes on the cases as they had already commenced treatment at the time of examination of the blood films, but, morphologically, they resembled those described by ROBERTS(1941), and named P. wilsoni. East African Med. Journal, 17, 215. The points of resemblance between them, made at the time from notes and camera lucida drawings, and those described by Dr. FIELD are: (1) Multiple invasion of single red cells with up to four parasites. (2) Distortion of the host cell (many were quite astonishingly distorted). (3) Compactness of the smaller parasites. (4) Closely packed schizonts. (5) Resemblance of parasites to P. malariae except for their presence in enlarged cells. The points of difference are as follows : (1) The corpuscle was always enlarged, sometimes very greatly so, and paler than normal. (2) Stippling of the cell either absent, or if present, of a faint P. malariae type, or trabeculation of the cell. (3) Parasites occasionally seen which were separated from the corpuscles in which they had grown. G
98
CORRESPONDENCE
(4) The multiple parasites in single cells were practically never vacuolated rings, but were of varied form and size. The chromatin often appeared separate from the cytoplasm, and in some cases the impression received by the eye was that of various little pieces of chromatin and cytoplasm dotted about the greatly enlarged cell. It is probable that the parasites describedby ROBERTS(1941) were abnormal fi)rms of P. vivax, but whether the original parasites we observed in 1937, and demonstrated at a meeting of this Society in 1938, were also abnormal forms of P. vivax, is more doubtful. We continue to hope to encounter them again, and have the opportunity of making repeated examinations and parasite drawings, together with a complete clinical history. l am, etc., MARGARET
MMariaLaboratory, Muheza, Tanganyika Territory, East Africa.
WILSON, M.B., D.T.M.