02304nas a2200337   4500000000100000008004100001260001300042653001500055653001000070653002200080653001000102653002100112653002800133653003800161653002700199653001100226653001100237653001200248653002500260653000900285653001600294653003000310653001400340653001700354100001800371245012000389300001100509490000700520520142500527022001401952       2004                            d  c2004 Mar10aAdolescent10aAdult10aBlotting, Western10aChild10aChild, Preschool10aCross-Sectional Studies10aEnzyme-Linked Immunosorbent Assay10aFamily Characteristics10aFemale10aHumans10aleprosy10aLongitudinal studies10aMale10aMiddle Aged10apolymerase chain reaction10aSri Lanka10aTuberculosis1 aDissanayake S00aRelative lack of clinical disease among household contacts of tuberculosis patients compared to leprosy households.  a156-640 v983 a<p>The incidence of clinical tuberculosis and clinical leprosy among household members of tuberculosis and leprosy patients in Sri Lanka was studied. The study period was approximately 20 years (January 1981 to December 2001) and the total number of patients and contacts were 325 and 968 for tuberculosis and 726 and 3066 for leprosy, respectively. While none of the tuberculosis patient households had more than 1 patient nor any contacts who developed clinical disease during the observation period, 20% (148/726) of the leprosy patients had more than 1 patient in the family and 0.9% (13/1403) of their contacts who were followed-up developed clinical leprosy during the observation period. Although the tuberculosis patient household contacts did not develop clinical disease, in 79% (88/112) of contacts who were tested by Western blot analysis, there was serologic evidence of Mycobacterium tuberculosis infection. These data show that in populations of comparable socio-economic, environmental and geographic locations, tuberculosis and leprosy show very different transmission patterns. In general, in tuberculosis household contacts, in spite of exposure, infection did not proceed to clinical disease. In contrast, a significant number of leprosy household contacts developed clinical leprosy. These findings have implications in the design and implementation of control programmes for these two diseases.</p>  a0035-9203