KAKWA: see BARI-SPEAKING TRIBES.
In 1881 a malaria-like fever, with great en largement of the spleen, was found to be causing serious mortality at the foot of the Garo hills in Assam, from whence it spread slowly eastward during the next two decades over some 200M. of the Brahmaputra valley, carrying off about one-third of the inhabitants.
It was attributed by successive investigators to hookworm disease, epidemic malaria, and Malta fever respectively, until in 1903 Leishman and Dono van independently discovered its cause in a new minute protozoal. parasite, Leishmania donovani, found in the spleen. In the fol lowing year L. Rogers developed a flagellate stage of the organism in cultures, and suggested a biting insect, probably the bedbug, as its carrier, a supposition which was supported by Patton demonstrating the flagellate stage of the parasite in bedbugs fed on the blood of kala-azar patients in 1905. But in 1925 Knowles and Napier, of the Calcutta School of Tropical Medicine, appear to have solved the difficult problem by incriminating a sand fly, Phlebotonius argentipes, as the true agent in transmitting the disease; this minute insect, together with kala-azar cases, being far more prevalent in areas of Calcutta with much vegetation than in the more crowded Indian quarter. After the discovery of the causative parasite in 1903 it was soon found that what had for a century been called malarial cachexia in Bengal was nothing but a widely distributed sporadic form of the Assam epidemic kala azar, the virulence of the latter being due to its invasion of an area previously free from the disease. The disease is now recog nized as being very prevalent over all Bengal, Behar, the eastern part of the United provinces and in Madras, but the compara tively dry Punjab and north-west frontier are practically free from the disease, a certain degree of humidity being necessary for it. A form of kala-azar especially affecting children is also prevalent all round the Mediterranean basin and in Egypt and the Sudan.
Symptoms.—Kala-azar is characterized by very prolonged fever, often typhoid-like in the early stages, and frequently show ing two or three rises and falls in 24 hours, the characteristic double remittent fever, but with long intervals of low continued or intermittent fever, the total duration being seldom less than seven months and often extending, with periods of freedom from fever, over several years; accompanied by extreme wasting, very great enlargement of the spleen, and later of the liver, some anaemia and extreme reduction of the white corpuscles of the blood, which lowers the resisting power of the patients to secon dary infections with septic diseases, pneumonia, dysentery and phthisis, which are far more frequently the ultimate cause of death than the original disease, the case mortality having been until recently from 8o to 96%.
As the result of his Assam researches of 1897, L. Rogers established a house and site infec tion of kala-azar and worked out a system of moving the sites of the villages and tea garden coolie lines, whereby the further prog ress of the epidemic up the Assam valley was checked for many years. J. Dodds Price successfully applied the same plan to stamping out the disease from a number of badly infected tea estates, thereby saving the industry in the Nowgong district. The debilitating effects of the 1918 influenza pandemic led to a recru descence of kala-azar in the Assam valley, including the more eastern and little infected area. F6rtunately by this time an effective treatment had been discovered in intravenous injection of tartar emetic and other antimony preparations, which now enables some 90% of the cases to be cured; a greater saving of life perhaps than has been effected in any such fatal illness by modern medical research, with the result that many thousand cases have been treated successfully each year in Assam and Bengal. Given adequate funds and organization, this, the most terrible of tropical fevers, might be nearly stamped out of the large areas which it has decimated for centuries past and further epidemics prevented.
See L. E. Napier and E. Muir,
(1923). (L. R.)