In view of the fact that Leishmania may be found in the intestinal ulcerations or in the kidneys there have been suggestions that the disease may be spread through the medium of faeces or urine. There is not the slightest evidence that the parasites could live in water which they might contaminate and the view that some sort of transmitting host might take up parasites from the faeces or urine is improbable, as the parasites have never been found in faeces or urine.
The fact that a distance of 300 yards seems to suffice for permanent protection of the uninfected excludes from consideration such transmitting agents as the mosquito or house fly.
The tendency of some to incriminate soil factors can be explained by the well-known fact that bedbugs can live for months without food, being ready to bite those entering an infected house even after long disuse as a habitation of man.
Infantile kala-azar may possibly be connected with the disease in dogs and may be transmitted by the agency of the flea but there is nothing like the evidence for this view that obtains for the bedbug theory in Indian kala-azar.
Pathology.—At autopsy there is noted marked emaciation with greatly enlarged spleen and liver, dropsical effusions and ulceration of the large intestine. The spleen is often enormously enlarged, rather firm but quite friable. The liver may at times show cirrhosis but the usual change is a distention of the endothelial cells of the intralobular capillaries with great numbers of parasites, as many as 100 or more parasites being at times found in a single cell. Not only do the endothelial cells of the liver contain parasites but those of the spleen, particularly the cells lining the venous sinuses as well as those of the pulp cords, the lymphatic glands and bone marrow. The parasites are present in the intestinal ulcerations of the terminal stages. Less frequently they are found in kidneys, adrenals, testicles, pancreas and lungs. Rarely, parasites may not be found at the autopsy of advanced cases. It is possible that the finding of coccus-like bodies in the cells of such cases may represent degenerated leishman bodies. The mesenteric and prevertebral lymph glands are swollen. The bone marrow is red.
When the phagocytic endothelial cells rupture the parasites are taken up by other cells and if by large mononuclear or polymorphonuclear cells may appear in the peripheral circulation. In possibly 80% of cases the parasites may be found after prolonged search in smears of peripheral blood. The leucopenia and large mononuclear increase are the blood features.
Symptomatology
Indian kala-azar.—As with all diseases tending to a chronic course it is difficult to be sure of the length of the period of incubation of kala-azar and various authorities have given it as from two to three weeks to several months. Manson states that one of his cases developed the initial fever of the disease ten days after arriving in the endemic area. As a rule the period of onset is rather indefinite. There may be a history of daily rigors, so that malaria is suspected, but it is found that the fever does not respond to quinine. The fever is usually of a low remittent type, rarely a low continued fever, in which the temperature does not exceed 101°F. At times however in the early stage the remittent fever is of a high type, the temperature reaching 104°F.
