agreed that results obtained from the use of H suspensions were inconclusive
and of little value as a help to diagnosis. A rising titre of agglutination to
TO and AO remained the diagnostic standard.
Several publications have recently appeared on the production of Vi
antibodies in the blood during an attack of typhoid fever and also during the
carrier stage. The authors of these articles suggest that in practically every
case of infection or the carrier stage of typhoid fever demonstrable amounts of
Vi antibody are developed.
In view of the above it was decided that investigations should be carried
out by selected laboratories with the possibility of the employment of suspen-
sions of Vi strains of typhoid bacilli for agglutination tests as a means of diagno-
sis. On the whole results obtained were disappointing but this to a large
extent is considered to be due to inexperience of officers concerned in the
correct reading of results obtained. Reports were rendered to the Officer in
charge, Enteric Laboratory, Kasauli who correlated results obtained. The
following extracts are taken from his consolidated report.
(a ) A large number of individuals suffering from diseases other than
typhoid fever may develop traces of Vi agglutinins in their blood;
occasionally this may be considerable.
(b) Although the majority of patients suffering from typhoid fever
develop appreciable amounts of Vi-antibody, several cases have
been collected where it has not been possible to demonstrate it.
(c) Vi agglutinins were not demonstrated in every carrier. Fours
cases were fully investigated, two convalescent temporary carrier.
and two healthy permanent carriers (two urinary and two faecal)
In two cases definite positive results were obtained. In another
the Vi-titre was very low, between 10 and 20, which in view of
the presence of traces of this antibody in so many non-enteric
cases cannot be considered very significant. In the last example
although Vi-antibody was present in low titres during the acute
condition none could be demonstrated during the temporary
carrier stage.
(d) There is evidence to show that Vi-agglutinins may appear very early
in the blood during an infection. In some cases it appears
before the 0 or H, and this fact may explain the very low or,
complete absence of, titre obtained in some of the cases where the
blood serum was first examined on the 8th day of illness or even
later.
(e) It has been stated that there appeared to be little relation between
the severity of the disease and the Vi content of the organism
responsible. This is well illustrated in a small epidemic investi-
gated. In 12 cultures examined from this epidemic (all the cases
were very seriously ill and two were fatal) only one was rich in
Vi-antigen and four, including one from a fatal case, were almost
completely devoid of this antigen and did not appear to be cap-
able to give rise to any Vi-antibody.
In next year's report it is hoped to record a fuller account of this aid to
diagnosis. All workers in Military Laboratories in India are now supplied with
Vi sus p ensions and they have also been issued with detailed instructions con-
cerning the method of carrying out the test and reading results.
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