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333
pleural and peritoneal linings show petechiae-
and both the intestinal and respiratory tracts are
injected. Another clinical type showing haemor-
rhagic gastro-cnteritis with little or no icterus
resembles canine typhus or Stuttgart disease and
is referred to as a haemorrhagic type by these
American workers. There is marked dehydration
and the mouth and anal openings are soiled. The
Mucosa of the buccal cavity is dry and covered
with diphtheritic deposits, and ulcers are present
on the tongue and margin of the lips. The viscera
are dark and the mucosa of the stomach, duode-
num, colon and rectum is infiltrated and dark
coloured. The liver is mottled and hyperaemic.
Hyperaemia and streaking of the renal medulla
is always apparent and the kidneys are slightly
enlarged, and soft. The onset is sudden in both
the icteric and haemorrhagic types of disease
and the temperature is high; in the haemorrhagic
or canine typhus type there is often a marked drop
in the temperature on the second day and this is
accompanied by anorexia, a marked thirst and
occasionally by persistent vomiting. This type
is seen predominantly in adult dogs and may be
confused with 'black tongue', from which it may
be differentiated by its rapid onset, the vomiting
and great depression early in the disease.
A chronic form of leptospirosis predominantly
characterised by a nephritis, a high non-protein-
nitrogen content of the blood and uraemia has
been recognised in Holland.
In the acute forms there is an incubation period
of about five to seven days and a spirochaetae-
mia. This is followed by a rapid clearing of the
blood stream with a reinvasion of the blood and
the formation of antibodies. As the antibodies
increase more organisms are removed from the
blood and become localised in the liver, kidneys,
spleen, cardiac muscle and bone marrow. Jaun-
dice is apparent in some cases and leptospirae are
present in the urine towards the first week of
illness and in non-fatal cases they are excreted
for about two to four weeks. The kidney is
probably the most important organ for diagnostic
purposes and advantage can be taken of the
development of antibodies, for they increase
rapidly in animals that recover and remain at a
significant titre for not less than a year [Gray,
1942].
Leptospirae in the living state may be studied
with dark background illumination and they
assume the appearance of bright filaments with
fine spirals throughout their length giving serrated
outlines. The ends are pointed and frequently
curved and they are actively motile. Leptos-
pirae may also be studied in films treated with
Leishman and Giemsa stains and by Fontana's
silver nitrate method. Various procedures of
tissue impregnation with silver nitrate are also
used and these have the advantage of conveying
an idea of the numbers and distribution of the
organisms in the tissues.
Growth may be
obtained in media containing a high percentage
of blood or serum, the optimum temperature
being from 30 to 37º C. The medium commonly
used is that of Schüffner or a modification and
contains 8 to 10 per cent sterile rabbit serum
In a suitable natural environment pathogenic
leptospirae may remain alive for months
[Buchanan, 1927].
Direct culture is often not satisfactory and re-
course is made to the use of guinea-pigs. Meyer
et al. use guinea-pigs of 50 to 100 grammes weight
and employ the intraperitoneal route. Emulsions
of kidney and liver are injected and passaged
through three to five series of animals. After
the third or fourth passage the guinea-pigs
lose weight and when killed show congested
viscera, injected lymph glands and distended
gall bladders. Gray [1942] uses guinea-pigs
of 100 to 150 grammes and if there is any risk
of the inoculum being contaminated then it may be
applied to the depilated abraded skin of the
abdomen. The taking of morning and evening
temperatures gives an early and often the sole
indication of infection, especially with primary
inoculation of suspected tissues, and the organism
may be virulent only after passage through two
or three guinea-pigs.
Agglutinins, lysins and complement fixing anti-
bodies appear towards the end of the first week of
disease increasing to a high level within five to
eight weeks. They persist for many months and
then decline over a period of one to three years.
If living leptospirae are brought into contact
with an active serum then both agglutination
and lysis may occur, whereas if the leptospirae
are formalinised agglutination occurs and lysis
is slight. These reactions may be observed under
a dark background and a test of this kind is now
commonly used. The complement fixation and
adhesion tests require a number of reagents and
offer no advantage (Meyer et al.). Serological
tests are useful for purposes of diagnosis and
identification of the leptospirae and although
cross reactions may occur there is usually a suffi-
cient difference to detect the type of infection or
the type of organism.
Coffin and Stubbs [1942] point out that if
accurate diagnosis is to be made then laboratory
procedures must be employed and those avail-
able are : (1) dark background examination of
blood, urine and tissue juices; (2) study of specially
stained tissue sections; (3) guinea-pig inocula-
tions; (4) serological procedure; (5) cultural
studies.