Risk to household contacts of tuberculous patients based on Mantoux test and antibody titre.

BACKGROUND Tuberculosis, being an infectious disease, carries a risk of infection to contacts attending tuberculous patients. This study was conducted to evaluate the risk for household contacts of tuberculous patients as compared to non-contacts. The study was conducted at PGMI, Gulab Devi Hospital and Defence Housing Authority Lahore. The study included 120 household contacts and 80 non-contacts. METHODS A Cross sectional study for evaluation of antituberculous antibodies levels by ELISA method in two groups; Mantoux positive household contacts 49, Mantoux negative household contacts 71 and normal healthy persons 'non contacts' 80. Routine Haematological investigations like HB, TLC and ESR were done by conventional methods and all the sera of 200 subjects included in the study were tested for IgM, IgG and IgA anti tuberculous antibodies by enzyme linked immunosorbant assay (ELISA). Purified protein derivative 0.1 ml containing 5 TU was injected intradermally. The test was read after 72 hours by measuring the induration around injection site of forearm. RESULTS There was no difference in the average age of the household contacts and non-contacts. The complaints of pyrexia, night sweats and weight loss were more in house hold contacts as compared to non-contacts. The awareness about BCG vaccination was equal in both. There were 49 contacts with positive Mantoux test while negative Mantoux test was found in 71 contacts. There were only three Mantoux positive among eighty non-contacts. There was no significant difference in the presence of IgM among household contacts as compared to non-contacts. However both IgG and IgA were present in significantly higher number of household contacts compared to non-contacts. CONCLUSION Household contacts of patients suffering from active pulmonary tuberculosis have more chances of being infected with Mycobacterium tuberculosis as compared to the healthy non-contact, as shown by the higher levels of antituberculous antibodies & positivity of Mantoux test.