The rapid strides which our knowledge has made during the past few years
in the subject of the filaria parasite have been mainly owing to the
diligent researches of Dr. Patrick Manson, who continues to work at the
question. In the last number of the _Medical Reports for China_, Dr.
Manson deals with the phenomenon known as "filarial periodicity," and
with the fate of embryo parasites not removed from the blood. The
intimate pathology of the disease, and the subject of abscess caused
by the death of the parent filaria, also receive further attention.
An endeavor to explain the phenomenon of "filarial periodicity" by an
appeal to the logical "method of concomitant variations" takes Manson
into an interesting excursion which is not productive of any positive
results; nor is any more certain conclusion come to with regard to the
fate of the embryos which disappear from the blood during the day time.
Manson does not incline to the view that there is a diurnal intermittent
reproduction of embryos with a corresponding destruction. An original
and important speculation is made with respect to the intimate pathology
of elephantiasis, chyluria, and lymph scrotum, which is thoroughly
worthy of consideration. Our readers are probably aware that the parent
filaria and the filaria sanguinis hominis may exist in the human body
without entailing any apparent disturbance. The diameter of an
embryo filaria is about the same as that of a red blood disk, one
three-thousandth of an inch. The dimensions of an ovum are one
seven-hundred-and-fiftieth by one five-hundredth of an inch. If we
imagine the parent filaria located in a distal lymphatic vessel to abort
and give birth to ova instead of embryos, it may be understood that the
ova might be unable to pass such narrow passages as the embryo could,
and this is really the hypothesis which Manson has put forward on the
strength of observations made on two cases. The true pathology of the
elephantoid diseases may thus be briefly summarized: A parent filaria in
a distant lymphatic prematurely expels her ova; these act as emboli
to the nearest lymphatic glands, whence ensues stasis of lymph,
regurgitation of lymph, and partial compensation by anastomoses of
lymphatic vessels; this brings about hypertrophy of tissues, and may go
on to lymphorrhoea or chyluria, according to the site of the obstructed
lymphatics. It may be objected that too much is assumed in supposing
that the parent worm is liable to miscarry. But as Manson had sufficient
evidence in two cases that such abortions had happened, he thinks it is
not too much to expect their more frequent occurrence. The explanation
given of the manner in which elephantoid disease is produced applies to
most, if not all, diseases, with one exception, which result from the
presence of the parasite in the human body. The death of the parent
parasite in the afferent lymphatic may give rise to an abscess, and the
frequency with which abscess of the scrotum or thigh is met with in
Chinese practice is, in Manson's opinion, attributable to this. Dr.
Manson's report closes with an account of a case of abscess of the
thigh, with varicose inguinal glands, in which fragments of a mature
worm were discovered in the contents of the abscess.--_Lancet_.
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