Histoplasmin Sensitivity in Uganda

and it is necessary in order to help to assess the significance of radiological changes found in the chest or bones. As in everything else, experience of the relative advantages of different methods is required. The test gives a positive result four to six weeks after primary infection, and thereafter a positive reaction means simply that a child has undergone primary infection. It does not mean that any particular illness is tuberculous in origin, but it emphasizes the possibility, or indeed with a young child the probability, that it is so. A negative reaction is important, for the presence of tuberculosis is practically dismissed unless the child is very ill, when other physical signs are almost certainly present. Two tests are in general use-the percutaneous (jelly) and intradermal (Mantoux). In the jelly test the skin is carefully cleaned with acetone or ether, and a petroleum jelly ointment containing Old Tuberculin is placed on the skin; usually the child's initial or a "v " mark is outlined with the jelly, to the length of about 1 in. (2.5 cm.). This is covered with a piece of strapping without any intervening lint. After 48 hours the strapping is removed and the skin examined 72 hours later-that is, after five days. This interval allows any strapping reaction to fade and gives a delayed tuberculin reaction time to appear. The result is not often in doubt. There is either no reaction whatsoever or, if positive, a reddish-brown slightly raised area; or sometimes a line of papules, not indurated or oedematous, will show on the skin in contact with the jelly. It is best to regard any reaction as positive until proved otherwise, but sometimes if only two or three papules are present the intradermal test will be necessary. We do not recommend the use of flourpaper (very fine sandpaper) in testing children under 5 years of age. The jelly test is roughly equivalent to 0.1 ml. of 1: 1,000 Old Tuberculin by intradermal injection. It is most useful in clinic work where repeated tests are necessary and time is not important. Avoiding a prick. the doctor retains the child's confidence. But it takes five days, and occasionally an intradermal tuberculin test is necessary afterwards. So if there is any urgency, if the child is ill and tuberculosis seems likely, an intradermal (Mantoux) test should be used. The intradermal test consists of the intradermal injection of 0.1 ml. of 1: 1,000 Old Tuberculin; 48 hours later a weal or area of induration more than 5 mm. in diameter indicates a positive reaction. Redness without induration is ignored, and redness surrounding a weal is not included in measurement. The reactions of the tests are therefore very different and should not be compared. That of the jelly is on the skina series of small spots, papules, or vesicles which sometimes coalesce ; that of the intradermal test is oedema in the skin at the site of injection. Every child with a positive reaction should be known to his family doctor, and it is most important that the results of tuberculin tests done in clinics or elsewhere should be communicated to him. It is also important that he should recognize the significance of the information and its value if the child becomes ill.