REPORT OF THE KING INSTITUTE GUINDY 13
(G) OTHER RESEARCHES AND REPORTS.
1. A rat flea, survey of the Madras Presidency.— It was proposed to the Govern
-ment of Madras to inaugurate a system of plague preventive measures by
constructing platforms for the sun disinfection of imported grains at important
railway stations which were centres of goods traffic and were situated on the
borders of plague-infected areas. But elaborate preventive measures against
plague are not necessary in districts, where prevailing fleas were not efficient
vectors of plague. Sufficient evidence regarding the geographical distribution of
the various fleas was therefore found necessary and a rat flea survey of different
parts of the Presidency has been commenced with the aid of a grant from the
Indian Research Fund Association obtained by Lt.-Col. A. J. H. Russell,
I . M . S . , D i r e c t o r o f P u b l i c H e a l t h , M a d r a s . I n C o l . R u s s e l l ’ s a b s e n c e o n l e a v e , t h e i n q u i r y
was supervised by Lt.-Col. H. H. King, I.M.S., till he proceeded on leave at the
end of March 1929.
So far, the western half of the Bellary District, Guntakal in the Anantapur
District, Periyakulam, Kambam Valley and Dindigul in the Madura District, and
Hosur in the Salem District have been surveyed. The findings are discussed in
a paper which is to appear in the Indian Journal of Medical Research, Vol. XVII,
July 1929.
2. Filariasis— (a) Filariasis survey in Saidapet.— This was completed last
year and some of the findings, e.g., relating to mosquito infection, were reported
in the annual report for 1927-28. Further investigations were made to determine
the source of filarial infection in mosquitoes caught in Saidapet. Apart from the
study of the structure of microfilariæ found ingested by the mosquitoes and of
the nature of their blood meal, an attempt was made to study the degree of
filarial infection in other animals and the capacity of those microfilariæ to develop
in c. fatigans. On the evidence thus obtained it was possible to exclude birds,
rabbits, dogs, and cattle from having been the source of filarial infection of
c. fatigans caught in houses except possibly to an exceedingly small degree. Major
portion if not nearly the whole infection reported was derived from man.
Further analysis of the data obtained during the survey has also brought
forward evidence to show that despite the similarity of chances of infection, the
amount of filarial disease in both sexes is associated with trades and habits of life
involving damage to lymphatics. Therefore to the two known factors in the
production of elephantiasis—infection with filariæ and subsequently with
streptococci—must be added the third the predisposing factor of strain and
damage to the lymphatics from the nature of occupation.
These and other findings are described in detail in a paper which will shortly
appear in the Indian Journal of Medical Research, Vol. XVII.
(b)
The adhesion phenomenon in filariasis.— This phenomenon was first,
worked out in the Institute. It is commonly observed that microfilariæ disappear
from blood in cases of elephantiasis. The explanation for this is to be sought for
in the above phenomenon. It was found that in the presence of specific serum
(e.g., from a case of elephantiasis), the leucocytes in the blood adhere to the
microfilariæ and so destroy them. This finding which is specific is likely to throw
considerable light on the mechanism of immunity in filariasis. A paper on this
subject was published in the Indian Journal of Medical Research, Vol. XVI, April
1929.
(c) Therapeutic researches .—Vaccines made from Streptococci isolated
from the elephantoid tissues are being tried in a large number of cases with
beneficial results.
3. Vaccine lymph— ( a) Experiments with dried lymph. .—Preliminary experi
-ments on the use of dried vaccine lymph were conducted in the Institute in
1923-24. It was found that dried vaccine gave results inferior to those normally
obtained with glycerine lymph. Since the subject is an important one further
investigation in all its aspects in the preparation and use of dried lymph is under
-taken. The results will be reported in due course.