Studies in Mediterranean leishmaniasis. 3. The leishmanin skin test in kala-azar.

Leishmanin skin testing was carried out in the Emilia-Romagna region of Northern Italy, the site of an outbreak of kala-azar in 1971-72, and in Catania, Eastern Sicily an old endemic focus of Mediterranean kala-azar. Nearly all the people who had recovered from kala-azar in the past gave positive skin tests. Active cases of kala-azar gave negative tests. There was a higher proportion of positive reactors amongst the household contacts and neighbours of cases of kala-azar than among the general population. Age specific leishmanin rates showed an increasing positive rate with age in Catania, comparable to those found in endemic areas in Kenya, but in the Emilia-Romagna area all age groups showed a high positivity rate suggesting a simultaneous exposure to infection. The age specific rates from Catania suggest an interruption in transmission 20-30 years ago. The leishmanin skin test is a useful tool for the study of the epidemiology of Mediterranean kala-azar.

Studies on Mediterranean leishmaniasis. IV. The leishmanin skin test in cutaneous leishmaniasis.

The leishmanin skin test was used in four different areas of the Italian Adriatic coast (Emilia Romagna, Marche, San Marino and Abruzzi), old endemic areas for cutaneous leishmaniasis. The test was found to be postitive in 80% of past infections, the 20% negative reactions being found in those who had been infected 20 or more years before. In the old endemic area of Teramo there was increasing positivity with age, with a sharp rise in the over 30 years age group suggesting that there had been a sudden break in transmission 30 years ago, coinciding with the DDT campaign of 1944-45. In San Marino in the past overt infection had occurred in a number of small microfoci, centred on houses surrounded by a larger number of inapparent infection. Control studies on a number of infectious and non-infectious diseases were all negative, and there was no relationship between tuberculin and leishmanin sensitivity.

Persistence of tanapox in Tana River valley.

Sera collected from inhabitants of the Tana River valley in 1971 were examined for antibody to tanapox virus. Neutralizing antibody was present in 16.3%. The levels of antibody and its presence in two children under the age of 10 years indicated that infection had been occurring in the area since the reported outbreak in 1962. A comparison of the incidence and distribution of antibodies in the same sera to West Nile virus revealed marked similarities suggesting that tanapox, like West Nile virus infections, might be transmitted in the same way-namely, by a culicine mosquito.

Tanapox: a new disease caused by a pox virus.

Two epidemics of a new virus disease, tanapox, occurred in 1957 and 1962 among the Wapakomo tribe along the Tana River in Kenya. Several hundred people were affected by a short febrile illness with headache and prostration and the disease was characterized by a single pock-like lesion on the upper part of the body. A pox virus, unrelated to the vaccinia-variola group, has been incriminated as the causative agent. The virus has a limited host range and has been grown only in human and monkey tissue cultures, and so far the only animals that have proved susceptible in the laboratory have been monkeys. The characteristic lesions have been reproduced in a human volunteer. Histopathological and electron microscopic studies indicate that the virus belongs to the pox group, but serological tests show that it differs from other animal pox viruses, including yabapox virus of monkeys. A similar if not identical pox virus has caused epidemics in primate colonies in the U.S.A. It is suggested that tanapox is a zoonosis and that the disease is transmitted from monkeys to man in Kenya.