title: Incidence of active pulmonary tuberculosis in patients with coincident filarial and/or intestinal helminth infections followed longitudinally in South India.
abstract: BACKGROUND
  Filarial (and other helminth) infections are known to modulate mycobacteria-specific pro-inflammatory cytokine responses necessary for maintaining latency in tuberculosis (TB). We sought to address whether helminth co-infection alters progression to active pulmonary TB in a co-endemic area of South India.
  
  
  RESULTS
  Incidence of active pulmonary TB was assessed in 5096 subjects from five villages among helminth-infected (hel⁺) and -uninfected (hel⁻) groups. Baseline stool examinations, circulating filarial antigen, and tuberculin skin testing (PPD) were performed along with chest radiographs, sputum microscopy, and culture. During three follow-up visits each 2.5 years, patients were assessed using PPD tests and questionnaires and--for those with potential symptoms of TB--sputum microscopy and culture. Of the 5096 subjects, 1923 were found to be hel⁺ and 3173 were hel⁻. Follow up interval stool examination could not be performed. In each group, 21 developed active TB over the course of the study. After adjusting for sex, age, BCG vaccination status, and PPD positivity, no difference was seen in active TB incidence between hel⁺ and hel- groups either at baseline (relative risk (RR) 1.60; 95% confidence interval (CI): 0.69, 3.71, P = 0·27), or when followed prospectively (RR 1.24; 95% CI: 0.48, 3.18, P = 0·66).
  
  
  CONCLUSIONS
  Our findings suggest that, despite the immunomodulatory effects of helminth infection, baseline co-morbid infection with these parasites had little effect on the clinical progression from latent to active pulmonary TB.
authors.affiliation: Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Soumya
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India.
authors.forename: Chockalingam
authors.initials: C
authors.lastname: Kolappan
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India.
authors.forename: Rangasamy
authors.initials: R
authors.lastname: Subramani
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India.
authors.forename: Punnathanathu G
authors.initials: PG
authors.lastname: Gopi
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India.
authors.forename: Vedhachalam
authors.initials: V
authors.lastname: Chandrasekaran
authors.affiliation: Biostatistics Research Branch, Division of Clinical Research, NIAID, NIH, Bethesda, Maryland, United States of America.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Fay
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India; NIAID/NIH-NIRT International Center for Excellence in Research Chetpet, Chennai, India.
authors.forename: Subash
authors.initials: S
authors.lastname: Babu
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India.
authors.forename: Vasanthapuram
authors.initials: V
authors.lastname: Kumaraswami
authors.affiliation: Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Nutman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D060085:Coinfection; D005260:Female; D005500:Follow-Up Studies; D006373:Helminthiasis / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007411:Intestinal Diseases, Parasitic / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult
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