The Epidemiology of Tuberculosis

1. The Epidemiology of Tuberculosis Lex Gibson, Virginia TB Program

2. TB Infection VS TB Disease Infection Disease TB Bacilli in Body Yes Yes PPD Usually Pos. Usually Pos. CXR Usually Normal Usually Abn. Sputum Smears/Cult Neg. Usually Pos. Symptoms None Cough, Fever, Wt. Loss Infected Yes Yes Infectious No Often, before treatment A “Case” of TB No Yes

3. What is a PPD? • Intradermal test of .1ml(5TU) of purified protein derivative. • Measures TB infection • False positives(cross reactions, non-specific in low risk populations) • False negatives(technique, storage) • Read in MM of induration

4. Reading the Mantoux Test • Read in 48-72 hours • Measure only raised area, not redness • Measure across the widest area • The diameter of the raised area should be measured • Measure and report results in millimeters

5. Interpreting the results 5mm is positive for those: • known to have or suspected of having HIV infection • close contacts of a person with infectious TB • with a chest x-ray suggestive of previous TB • who inject drugs(if HIV status unknown)

6. 10 mm is positive for those: • with certain medical conditions, excluding HIV infection • who inject drugs(if HIV negative) • foreign born persons from areas where TB is common • medically underserved, low income pop- ulations, including high-risk racial and ethnic groups • Residents of long term care facilities • Children younger than 4 years of age • Locally identified high risk groups

7. Determining Infectiousness • Smear Results • CXR Findings • Symptoms • Smear Results • CXR Findings • Symptoms

8. Increased Risk of Transmission • Infectiousness of Source • Duration of Exposure • Environment • Susceptibility of Contact

9. Contact Investigation • Screening individuals who have shared the same air as an infectious case of TB • Investigations are done systematically • Significant reactors receive a cxr and are evaluated for Treatment of disease or preventive therapy

10. Concentric Circle Community Casual/Work close

11. Scenario 1 • Twenty-eight year old school teacher has a positive PPD during a routine screening. No risk factors for TB. What do you do? • CXR shows pleural effusions. What's next? • Obtain sputum, pleural specimen, and possibly start on multiple anti-TB drugs. Sputum's are negative but pleural specimen is sm. Pos. • Now what do you do?

12. Contact investigation- All family members have negative PPD’s and are asymptomatic, is further testing necessary? • Normally not……unfortunately, word spread through the community that an elementary school teacher has TB. The media, parents and school system are demanding that PPD’s be done on everyone. What do you do?

13. Educate media, parents and school system • Your initial compromise is to skin test just one classroom rather than the entire school, but your health department receives 45% of its funding from the locality. The city council/board of supervisors wants to know why you are refusing to protect their school children from getting TB. What do you do?

14. If political pressure prevails and the entire school is tested, what might be some of the consequences? • This is a low risk population group, greater than 50% of the positive PPD’s identified will be false positives. Preventive treatment with INH exposes the individual to possible liver damage from the INH

15. Scenario 2 A sputum smear, culture positive Mtb case is diagnosed in a large open factory that manufactures circuit boards. Air is recirculated within the facility. Three other cases have been diagnosed in the facility during the past three years. Over 90% of the employees are from the Philippines and previous contact investigations have demonstrated a 70-80% reactor rate. Less than 7% of past positives have completed an adequate course of treatment for latent TB infection. All close family contacts are previous positive reactors. How do you proceed with the investigation?

16. Who would you screen and what tools would you use? • PPD past negatives in the immediate vicinity of the case, factory wide symptom assessment of past positives, and collect sputums on those with signs and symptoms

17. TB Advances Over Time 400 B.C. Syndrome Described 1882 Bacteria Identified 1895 X-Ray Invented 1934 PPD Available 1950 Effective Therapy 1990 DOT FUTURE ??

18. Funding Trends Not adjusted for inflation nor salary increases

19. Global Tuberculosis • 8-10 Million new cases/year • 2-3 million deaths/year • Tuberculosis is the 2nd leading cause of deaths by infectious diseases

20. Tuberculosis in the U.S. • 15 million infected • 17,000 + new cases per year • TB cases decreased steadily until 1985, then increased and has now begun to decrease again

21. TB Case Rates US &Virginia1987-1999

22. Epidemiology of TuberculosisVirginia-1999 • 334 Cases of TB in 1999 • 4.9/100,000 • 5000+ people starting INH • 77,000+ skin-tests given • 4,000+ contacts identified

25. Case rates for selected groupsIn Virginia(1996) • Homeless- 411.3 /100,000 • Vietnamese- 159.5 /100,000 • Guatemalan- 108.3 /100,000 • Korean- 63 /100,000 • Philippines-59.9 /100,000 • Foreign born- 49.7 /100,000 • Nursing & Adult Homes- 39.7 /100,000

26. Case Rates for selected groups • Chinese- 37.7 /100,000 • Corrections- 8.9 /100,000 • Hispanic- 26.8 /100,000 • >65 years - 17.3 /100,000 • U.S. born minorities- 8.1 /100,000 • U.S. born whites- 2.1 /100,000

27. 1996

28. Percent of Total TB by RaceVirginia -1992-1999

29. US & Foreign-Born TB CasesVirginia 1992-1999

30. % of Total TB By Age GroupVirginia 1992-1999

31. % Foreign-Born By Age GroupVirginia 1992-1999

32. % US Whites By Age GroupVirginia 1992-1999

33. % US Blacks By Age GroupVirginia 1992-1999

34. % Foreign-Born By RaceVirginia 1992-1999

35. % Foreign-born CasesBy Region* *Based on WHO regions

36. Foreign-Born TB Cases Arrival to Onset of Disease1995 - 1997 • Less than 1 year 36.1% • From 1 to 2 years 11.1% • From 3 to 5 years 15.3% • Over 5 years 31.5% • Unknown 6.0%

37. Tuberculosis by Agegroup and Foreign-born1999

38. TB/HIV-1999 • 324 TB Cases Reported Prior to Death • 231 (72%) were offered HIV testing • 197(85%) were tested • 16 (8%) were Positive Agegroup

39. % TB Cases Tested withDrug Resistance 1993-1999

40. % Drug Resistant Foreign-Born & US Born1993-1999

41. DOT • The standard of treatment • Where one observes client taking meds • 216 patients on DOT in 1999 • 66.6 % of cases on DOT in 1999 Percent

42. % TB Cases with Social Problems that Impact Treatment1993-1999

43. Quarantine/Legal Isolation • Intervention of last Resort • Difficult to Accomplish(weak laws, human rights issues) • Limited options for isolation (Corrections) • Have other interventions been exhausted?