Human blood seems to inhibit growth so that N. N. N. medium for cultivating Leishmania should be made from rabbit blood.
The culture should be kept at a temperature of about 22°C.
One should always first examine a smear of the peripheral blood for parasites in polymorphonuclear or large mononuclear leucocytes. The Sudan Commission found leishman bodies in the peripheral blood of 13 out of 15 cases so examined, but rarely did they find more than one parasite-containing leucocyte to a slide.
It is well to select a time when some pyogenic infection causes a leucocytosis.
Quite recently Wenyon and others have noted the desirability of culturing the peripheral blood in N. N. N. medium. Diagnosis may be made in this way, provided one wait from two to three weeks before reporting negatively as to the presence of flagellated Leishmania in the cultures. As before stated, strict asepsis and a room temperature are requisite for flagellate development.
It has been noted that artificial pustulation might assist in diagnosis by giving a multitude of polymorphonuclear leucocytes for examination for phagocytized Leishmania.
Cochran has recently noted the advisability of excising a lymphatic gland and making gland smears to examine for Leishmania. Others have reported success with gland puncture as utilized in the gland of trypanosomiasis.
Animal inoculation has no place in diagnosis as such a procedure is but rarely successful. Ray has recently proposed a turbidity test in which about 2 drops of blood are added to 20 drops of distilled water. Instead of giving a clear solution of haemoglobin we have a turbidity followed later by a white flocculent precipitate. It is now thought that this turbidity is due to excess of serum globulin in the blood of this disease and the test can be carried out with serum instead of whole blood.
Prognosis.—Kala-azar is a chronic disease in the great majority of cases although both the adult and infantile types may show cases rapidly running to a fatal termination. Marked intestinal disturbance makes for a bad prognosis as does also a low large mononuclear percentage. A marked leucopenia is a bad sign particularly when associated with such low polymorphonuclear percentages as ten to twenty. Rogers notes that in children the polymorphonuclears several times did not give more than 5% of the total leucocyte percentage.