The Epidemiology of Tuberculosis Lex Gibson, Virginia TB Program

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

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

Reading the Mantoux Test Read in 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

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)

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

Determining Infectiousness Smear Results CXR Findings Symptoms Smear Results CXR Findings Symptoms

Increased Risk of Transmission Infectiousness of Source Duration of Exposure Environment Susceptibility of Contact

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

Concentric Circle close Casual/Work Community

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?

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?

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?

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

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 % 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?

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

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

Funding Trends Not adjusted for inflation nor salary increases

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

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

TB Case Rates US &Virginia

Epidemiology of Tuberculosis Virginia Cases of TB in /100, people starting INH 77,000+ skin-tests given 4,000+ contacts identified

Case rates for selected groups In Virginia(1996) Homeless /100,000 Vietnamese /100,000 Guatemalan /100,000 Korean- 63 /100,000 Philippines-59.9 /100,000 Foreign born /100,000 Nursing & Adult Homes /100,000

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

1996

Percent of Total TB by Race Virginia

US & Foreign-Born TB Cases Virginia

% of Total TB By Age Group Virginia

% Foreign-Born By Age Group Virginia

% US Whites By Age Group Virginia

% US Blacks By Age Group Virginia

% Foreign-Born By Race Virginia

% Foreign-born Cases By Region* *Based on WHO regions

Foreign-Born TB Cases Arrival to Onset of Disease Less than 1 year36.1% From 1 to 2 years11.1% From 3 to 5 years15.3% Over 5 years31.5% Unknown6.0%

Tuberculosis by Agegroup and Foreign-born 1999

TB/HIV TB Cases Reported Prior to Death 231 (72%) were offered HIV testing 197(85%) were tested 16 (8%) were Positive Agegroup

% TB Cases Tested with Drug Resistance

% Drug Resistant Foreign-Born & US Born

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

% TB Cases with Social Problems that Impact Treatment

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?