46 
SPIR0CHJ3T0SIS OF SUDANP^SK FOWLS 
The 
leucocytes 
Incubation 
period 
The disease 
in ifuinea 
fowls 
length, mecliuin forms with 5 spirals and a length of 12 p, fairly long forms with 
8 spirals like h, measuring 16-5 in length, a very frequent size, and extra long forms 
with as many as 9 spirals and possessing a length of 19'5 n. In addition, there are the 
combined forms exhibiting the appearance of a thin filament in the centre where the two 
parasites are in opposition by their fine extremities. The types of leucocyte found in the 
infected blood are shown in Plate V., fig. 2. Large, vacuolated mononuclears, like those 
described by Levaditi, are present, and so are basophilic lymphocytes. In the chronic stage 
I am inclined to think that there is constantly an eosinophilia. In some cases it is certainly 
very marked. In a ifird dead of the acute disease imt little is found post mortem. There is 
marasmus, evidence of anaemia and congestion, and enlargement of the spleen—the organ 
varying much in size. Sometimes the liver is also congested and enlarged. All the embedded 
specimens of organs—lung, spleen, liver, kidneys and lymph glands—were, as stated, lost in 
the fire, and one has not been able to study the histo-pathology of the acute disease to any 
extent. Nor has it always been easy to secure fowls showing spirochaetes in their blood, while, 
owing to the fact that many Sudanese fowls possess a natural or acquired immunity, it was 
difficult to maintain the strain. 
Inoculation of the hlood of one of the Leghorn fowls into a gerhil gave negative results. 
As in Brazilian sej)tic£emia, so here, there is what may he called a crisis prior to which 
the spirochaetes agglutinate into clumps, and immediately after which they are not to be found 
in the blood by ordinary methods of examination. 
The temperature, as a rule, is high, about 109° F., and falls at the crisis. The post- 
critical aspect of the disease will be discussed separately, as it presents special points of 
interest. 
In the case of the Leghorn fowls, numerous larv® of Argas ticks were found clinging to 
the bare patches under their wings. An apparently healthy Sudanese fowl was put into the 
infected hen-run, and in two days showed spirochaetes in its blood. It was put into the fowl- 
house on December 4th, on December 6th it was found infected, but not severely, and by 
December 9th all parasites had disappeared from its peripheral blood. It continued to 
improve, but on the 17th was found to have passed into what I have termed the “after phase” 
of the infection, and ran a chronic course with eventual complete recovery. 
Several other experiments showed that the tick was effective. In one instance a female 
tick, fed on a fowl with spirochaetes in its blood, was dissected after Christophers’ method, and 
the entry of a spirochaete into one of the eggs was observed, or at least an appearance very 
suggestive of this procedure. 
The incubation period in experimental inoculation seems to be about forty-eight hours. 
It is difficult to determine the time accurately, as at first the infection is usually very slight, 
and may not be recognised until the parasites have multiplied considerably in the blood. 
I found no local multiplication, i.e. at the site of infection. .\s regards other birds, I recently 
found a spirocheetosis in geese at Khartoum North, which I have reason to believe is due 
to the same parasite, and in which there is an “after phase” precisely similar to that occurring 
in the fowl disease. I have never found pigeons affected, and I have not used them in 
experimental work. Dr. Wenyon found guinea fowls on the White Nile with spirochtetes 
in their hlood, and discovered infected fowls in the Southern Soudan, so that probably the 
disease is wide-spread. We now know that a specific tick is not required for Sp. gallinarum, 
and that three species of Argasidm can transmit that parasite. It is quite probable that 
several are operative in Sudan spirochsetosis, hut so far Argas persicus only has been proved 
to be a carrier. 
I have several times tried to inoculate gerbils, but have invariably failed. It is probable 
that this is an avian spirochaetosis, non-transmissihle to mammals. 
