REPORT OF THE KING INSTITUTE, GUINDY

13

        (17) Investigation of cholera at Erode by Dr. R. Sanjivi Rao.—An explosive
outbreak occurred in a boys' boarding school, the number of attacks on successive
days being 27, 18, 4, 2—51 in all, of whom 32 died. The epidemic was almost
certainly water borne, and was caused either by infection of a well from an
trenching ground only 30 yards away, or by contamination of the drinking water
in a barrel which was filled by hand. A report was submitted to Government.

        (18) Investigation of an epidemic of typhoid fever in Cocanada by Dr.
K. V. Venkataraman.—Ten cases of typhoid fever (three fatal) occurred in a girls'
boarding school. The investigation showed that the outbreak was probably due
to a carrier who had assisted in the kitchen. A report was submitted to
Government.

        (19) Investigation of an epidemic of jaundice in Alipuram Jail by Dr.
R. Sanjivi Rao.—The disease was of a very mild type indeed, with usually no
fever at all, and had occurred mainly in the hot months from March to June. A
thorough search was made for leptospira but they were not found. No organism
of the typhoid group were found in the faeces. There was not a single case
showing any of the more severe signs of Weil's disease. The disease was perhaps
due to a virus. A similar disease has been reported in several parts of the world.
A full description of the investigation is given in a paper by Dr. C. G. Pandit and
Dr. Sanjivi Rao which is being published in the Indian Medical Gazetté.

        (20) Filariasis.—With a view to ascertain the influence of seasonal varia-
tion on the filarial infection of mosquitoes in nature, 1,587 mosquitoes were dis-
sected from December 1930 to 30th September 1931—all female C. fatigans caught
from one locality in Saidapet. Table XIII shows that the rate of development of
the f. larvae in the infected mosquitoes is higher in the months that have a high
percentage of humidity. This confirms the experimental evidence obtained by
Sunder Rao and M. O. T. Ayyangar.

        (21) Katadyn sterilisation of water.—Recently a proprietary (and unfor-
tunately secret) silver preparation called Katadyn has been put on the market as
a good steriliser of water. Since there was the possibility of its being of use,
more particularly for chemically pure waters with a low organic content and for
small or domestic installations, its properties have been investigated by our Water
Section bacteriologists, Mr. T. N. S. Raghavachari and Mr. P. V. Sitarama Ayyar
at my request. The investigation is continuing and will be published in due
course. So far, contact with impregnated materials has been found to consider-
ably diminish the bacteria present in clear waters, further the water treated
retains a germicidal action which varies with the period of previous contact and
with the amount of material then used, i.e., presumably small quantities of the
silver preparation pass into the water.

        (22) The serological classification of lactose fermenters found in water as a
guide to potability.—Rao Bahadur Dr. T. Sitapati Ayyar has completed his
paper on this subject and is sending it for publication. Polyvalent sera against
human and bovine strains were prepared and the lactose fermenters found in
natural waters, in soils, and in the faeces of animals were tested for agglutination
by these sera. The findings are of great interest in throwing light on the source
of coliform organisms in water and in suggesting the use of this serological method
to determine their origin.

        (23) Work for the water and Sewage Purification Committee—October-
December 1930.—The comparison of the percolators mentioned in our last report
was continued. The two percolators last mentioned—a coarse percolator and a
shallow fine percolator, did very well, and even gave a slightly greater reduction
of organic matter than the other two percolators, these had been started later, so
only a comparative equality can be claimed. In the other percolators Sholingher
stone was found definitely inferior to Pallavaram granite, for it greatly encouraged
the growth of thick felted masses of blue green algae.

        From January the Committee tried the effect of altering the depth of the
drainage layers of submerged sand filters for it had been suggested that
the results of the experimental filters will not hold good for the ordinary
Madras Filters, since while in the latter the draining and collecting layers was