Clinical pathology of the blood : a treatise on the general principles and special applications of hematology / by James Ewing.

  • Ewing, James, 1866-1943.
Date:
1904
Catalogue details

Licence: In copyright

Credit: Clinical pathology of the blood : a treatise on the general principles and special applications of hematology / by James Ewing. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    (males) to 94 mm. (females) iu length, and looks like an animated white thread. Its movements are active and wriggling, the female tending to coil. The young filaria are discharged into the lymph, and, traversing the lobes, reach the blood stream. The reason of their exclusive appearance during the night is not known. Usually the presence of this worm and its embryos leads to no appreciable disturbance in the body of the host, and numerous cases have been discovered entirely by accident. In some cases chronic inflammation of the lymphatics results in a variety of pathological conditions, principally chyluria, lymphangitis, lymph scrotum, etc., and probably also to elephantiasis Arabum. The embryo^ of Filaria nodurna is a slender, snake-like worm, 3 mm. by 0.0075 mm. in dimensions, with sharp-pointed tail tapering for about one-fifth the length of the body, and a blunt head. The head is composed of a six-lipped prepuce covering an extensive proboscis on which is a protrusible spine. The entire worm is enclosed in a delicate, hyaline, transparent sheath, which protrudes beyond head or tail, and within which the animal moves. This sheath exhibits fine cross-striations. The movements are actively lashing, writhino-, coiling, and uncoiling, but with little or no tendency/ toward locomotion. The movements continue for several hours, or until the blood suffers drying. Occurrence in the Blood. The embryos begin to ma-ke their appear- ance in the blood from five to seven o'clock in the evening. The numbers increase for several hours during rest in bed, and after mid- night they usually become less abundant,disappearing at seven or eight in the morning, but an occasional specimen may sometimes be found at any time in the day. This remarkable periodicity depends on the habits of the host, since it becomes transposed when the subjects sleep in the daytime, and it is considerably disturbed by irregular habits and by fever. It is also adapted to the nocturnal habits of the mosquito. The numbers of filaria to be found in the blood depend upon the time of the examination and upon the number of parent worms, but for the same patients they are usually quite uniform. From ten to fifty may be found under one cover-glass specimen, but they are often much less abundant. Several hours' search through thick blood smears may be required for the demonstration of a single filaria embryo, in cases in which they are present, though very scarce. It is sometimes to be observed that the results of the blood examination are negative as long as the patient is going about, although a moderate number of embryos are found after the patient has been in bed a few days. Changes in the red cells referable to the presence of filaria embryos are not usually demonstrable. Even when present iu enormous numbers and for many years the parasites exert no deleterious action on the blood, and anemia, when present, must be referable to secondary causes. Calvert examined the blood at hourly intervals for twenty-four hours in two cases of filariasis, finding leucocytosis, reaching 26,666 and 14,000. The eosinophile cells varied from 8 to 22 per cent, in