• Tuberculosis  

Tuberculosis  
1. DISEASE REPORTING
A. Purposes of Reporting and Surveillance
1. To identify and ensure the adequate evaluation and treatment of persons with TB disease.
2. To identify the contacts of TB cases and ensure their evaluation.
3. To ensure that all eligible infected contacts are offered and complete preventive therapy
B. Legal Reporting Requirements
1. Health care providers: immediately notifiable to local health jurisdiction (WAC 246-101-
101).
2. Hospital: immediately notifiable to local health jurisdiction (WAC 246-101-301).
3. Laboratories: initial culture notifiable to local health jurisdiction within two days; (WAC
246-101-201).
4. Local health jurisdictions: notifiable to the Washington State Department of Health
(DOH) within 7 days of case investigation or summary required within 21 days (WAC
246-101).
C. Local Health Jurisdiction Investigation Responsibilities
1. Start the initial assessment of the patient within ≤ 1 work day of receiving the case report
and do or assure the following:
http://www.doh.wa.gov/cfh/TB/Manual/Sections/Section1.pdf, page 1.11
2. Communicate to Washington State TB program staff:
Enter case into TB Public Health Issue Management System (PHIMS) within 7 days
of the LHJ receiving notification of the suspect case AND
Submit the “Contact Investigation Form” to WA State TB Services within 2 weeks.
D. Washington State Tuberculosis Program Objectives through 2009
1. All newly diagnosed cases of TB will be reported to CDC using the electronic reporting
system developed by the Washington State Department of Health, called PHIMS. There will
be at least 95% completeness for the key variables in the expanded RVCT.
2. At least 80% of immigrants and refugees designated as Class B1, B2 were appropriately
evaluated within 60 days.
3. At least 90% of patients with newly diagnosed TB, for whom therapy for 12 months or less is
indicated, will complete a course of curative TB treatment within 12 months of initiation of
treatment.
4. At least 80% of patients being treated for active tuberculosis will be on Directly Observed
Therapy (DOT).
5. HIV status will be reported for at least 90% of all newly reported culture-positive TB cases
age 25–44.
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6. Drug susceptibility results will be reported for at least 95% of all newly reported, culture
positive TB cases.
7. Decrease the TB incidence rate to 13.0 cases / 100,000 among American Indian/ Native
Alaskan persons.
8. Contacts will be identified for at least 80% of newly reported sputum AFB-smear positive
TB cases.
9. At least 60% of contacts to sputum AFB-smear positive TB cases will be evaluated for
infection and disease.
10. At least 60% of infected contacts who are started on treatment for latent TB infection will
complete a regimen.
2. THE DISEASE AND ITS EPIDEMIOLOGY
A. Etiologic Agent
Tuberculosis is a communicable disease caused by Mycobacterium tuberculosis, or the
tubercle bacillus.
B. Description of Illness
When droplet nuclei are inhaled, most of the larger particles become lodged in the upper
respiratory tract, where infection is unlikely to develop. However, smaller droplet nuclei
containing the tubercle bacilli may reach the alveoli, where infection begins.
The tubercle bacilli that reach the alveoli are ingested by alveolar macrophages; the
majority of these bacilli are destroyed or inhibited. A small number multiply
intracellularly and are released when the macrophages die. These bacilli can spread
through the lymphatic channels to regional lymph nodes and then through the
bloodstream to more distant tissues and organs, including areas in which TB disease is
most likely to develop: the apices of the lungs, the kidneys, the brain, and bone.
Extracellular bacilli attract macrophages from the bloodstream. The immune response
kills most of the bacilli, leading to the formation of a granuloma. At this point the person
has TB infection, which can be detected by using the tuberculin skin test or IGRA (IFN-g
release assay). It may take 2-10 weeks for the infected person to develop a positive
reaction to the tuberculin skin test. Immune responses soon develop to kill the bacilli.
Within 2 to 10 weeks after infection, the immune system is usually able to halt the
multiplication of the tubercle bacilli, preventing further spread.
Persons who are infected with M. tuberculosis, but who do not have TB disease cannot
spread the infection to other people. TB infection in a person who does not have TB
disease is not considered a case of TB and is often referred to as latent TB infection
(LTBI).
When the immune system is not able to halt the multiplication of tubercle bacilli, TB
disease results. TB disease presents as pulmonary TB (80%), extrapulmonary TB (20%),
or a combination of the two. The symptoms of pulmonary TB include cough, chest pain,
and hemoptysis; the specific symptoms of extrapulmonary TB depend on the site of
disease. Systemic symptoms consistent with TB include fever, chills, night sweats,
appetite loss, weight loss, and easy fatigability.
C. Tuberculosis in Washington State
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Washington experienced a slight decrease in the number of TB cases with 291 cases
reported in 2007 vs. 228 cases reported in 2008. The crude incidence rate of TB was an
all time low (4.4/100,000 in 2007 vs. 3.5/100,000 in 2008). Sixteen of the 39 counties in
Washington reported no new cases of TB in 2008 and 17 reported five or fewer cases.
Ten counties reported greater than five TB cases. King (121), Snohomish (25) and Pierce
(18) accounted for seventy-two percent of 2008 cases in Washington State.
Seventy-six percent of the 2008 tuberculosis cases in Washington were among foreign-
born immigrants or refugees from counties with high rates of tuberculosis; Vietnam,
Mexico, the Philippines, or Ethiopia. The proportion of foreign-born cases continues to
rise in Washington (75% in 2007 vs. 76% in 2008).
Most TB cases among foreign-born people are likely the result of reactivation of
infection acquired abroad, although some transmission is occurring in the U.S. The risk
of disease among the foreign-born also appears related to chronological age and age at
immigration; younger people and those who immigrated at younger ages are at lower risk
for subsequent infection with TB.
D. Reservoir
Primarily humans, rarely primates; in some areas, diseased cattle, badgers, swine, and
other mammals are infected.
E. Modes of Transmission
TB is spread from person to person through the air. When a person with pulmonary or
laryngeal TB coughs, sneezes, speaks, or sings, droplet nuclei containing M. tuberculosis
are expelled into the air. Depending on the environment, these tiny particles (1–5
microns in diameter) can remain suspended in the air for several hours.
If another person inhales air containing droplet nuclei, transmission may occur. The
probability that TB will be transmitted depends on four factors:
1. The infectiousness of the person with TB (the number of organisms expelled into the
air),
2. The environment in which exposure occurred,
3. The duration of exposure, and
4. The virulence of the organism.
The best way to stop transmission is to isolate patients with infectious TB immediately
and start effective TB therapy. Infectiousness declines rapidly after adequate therapy is
started, as long as the patient adheres to the prescribed regimen.
Persons at the highest risk of becoming infected with M. tuberculosis are close contacts,
persons who had prolonged, frequent, or intense contact with a person with infectious
TB. Close contacts may be family members, roommates, friends, coworkers, or others.
Data collected by CDC since 1987 show that infection rates have been relatively stable,
ranging from 21% to 23% for the contacts of infectious TB patients. HIV-positive
persons with TB disease are not considered more infectious than HIV-negative persons
with TB disease.
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Extrapulmonary TB is rarely contagious (except for laryngeal TB); however,
transmission from extrapulmonary sites has been reported during aerosol-producing
procedures, such as autopsies and tissue irrigation.
F. Incubation Period
From infection to development of a positive Tuberculin Skin Test (TST) or IGRA is 2 to
10 weeks. The risk of developing tuberculosis disease is highest during the 6 months after
infection and remains high for 2 years; however, many years can elapse between initial
infection and disease.
G. Period of Communicability
Determining the infectious period focuses the investigation on those contacts most likely
to be at risk for infection and sets the time frame for testing contacts. Because the start of
the infectious period cannot be determined with precision by available methods, a
practical estimation is necessary. On the basis of expert opinion, a person should be
considered infectious approximately 3 months prior to diagnosis. In certain
circumstances, persons may have been communicable for longer than three months prior
to diagnosis.) For example, a patient (or the patient's associates) might have been aware
of protracted illness (in extreme cases, >1 year). Information from the patient interview
and from other sources should be assembled to assist in estimating the infectious period.
Helpful details are the approximate dates that TB symptoms were noticed,
mycobacteriologic results, and extent of disease (especially the presence of large lung
cavities, which imply prolonged illness and infectiousness).
H. Treatment
For most patients, the preferred regimen for treating TB disease consists of an initial 2-
month phase of four drugs: isoniazid, rifampin, pyrazinamide, and ethambutol followed
by a 4-month continuation phase of isoniazid and rifampin. Streptomycin may be
substituted for ethambutol, but must be given by injection. Ethambutol (or streptomycin)
can be discontinued when drug susceptibility results show the infecting organism to be
fully drug-susceptible. TB treatment regimens may need to be altered for HIV-positive
patients taking HIV protease inhibitors. Whenever possible, the care for HIV-related TB
should be provided by or in consultation with experts in the management of both TB and
HIV disease. The major determinant of the outcome of treatment is patient adherence to
the drug regimen. Thus, careful attention should be paid to measures designed to foster
adherence, and treating all patients with directly observed therapy (DOT) is strongly
recommended.
Multidrug-resistant TB (i.e., TB resistant to both isoniazid and rifampin) presents
difficult treatment problems and requires expert consultation. The consequences of
treatment failure and further acquired drug resistance make DOT a high priority for cases
of drug-resistant TB.
For additional information regarding treatment of TB:
http://www.doh.wa.gov/cfh/TB/Manual/Sections/Section5.pdf
3. CASE DEFINITIONS
A. Clinical Case Definition (must meet ALL of the following criteria):
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• Positive tuberculin skin test (negative test is allowed for those patients with proven
anergy or an AIDS diagnosis); AND
• Other signs and symptoms compatible with TB, such as an abnormal or unstable chest x-
ray or clinical evidence of current disease; AND
• X-ray improvement on chemotherapy; AND
• Treatment with two or more anti-tuberculosis medications; AND
• Completed diagnostic evaluation.
B. Laboratory Criteria for Diagnosis (must meet ANY of the following criteria)
• Isolation of Mycobacterium tuberculosis using culture techniques from a clinical
specimen; OR
• Demonstration of Mycobacterium tuberculosis from a clinical specimen by DNA probe
or mycolic acid pattern on high-pressure liquid chromatography; OR
• Demonstration of acid-fast bacilli in a clinical specimen when a culture has not been or
cannot be obtained in a patient with clinical symptoms of tuberculosis.
C. Case Definition
• Suspect Tuberculosis - Any person who reports clinical symptoms associated with TB,
e.g. productive, prolonged cough, chest pain, hemoptysis, fever, chills, loss of appetite, or
weight loss, and is evaluated by a medical practitioner for tuberculosis, which may
include diagnostic X-rays and bacteriology collection, is considered a suspect. All
practicing physicians are required by Washington State law to report all suspects of TB to
their local health authorities immediately (WAC 246 -101-101); in turn, local health
authorities are required to report these suspects within seven days to the WA State TB
Services (WAC 246 -101- 510).
• Clinical Case definition – A case that meets the following criteria: A positive tuberculin
skin tests, other signs and symptoms compatible with tuberculosis, treatment with two or
more antituberculosis medications, completed diagnostic evaluation.
• Laboratory criteria for diagnosis- Isolation of M. tuberculosis from a clinical specimen
or, demonstration of M. tuberculosis from a clinical specimen by nucleic acid
amplification test or, demonstration of acid-fast bacilli in a clinical specimen when a
culture has not been or cannot be obtained.
• Confirmed Tuberculosis: a case that meets the clinical case definition or is laboratory
confirmed
4. DIAGNOSIS AND LABORATORY SERVICES
A. Diagnosis
Persons suspected of having TB should be referred for a medical evaluation, which
should include a medical history, a physical examination, a test for TB including a
Mantoux or IGRA, a chest radiograph, and any appropriate bacteriologic or histologic
examinations. Positive bacteriologic cultures for M. tuberculosis confirm the diagnosis
of TB. Clinicians should not wait for bacteriologic culture results before starting therapy.
Therapy should be started when the potential risks of TB exceed the risk of therapy.
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http://www.doh.wa.gov/cfh/TB/Manual/Sections/Section10.pdf
B. Tests Available at PHL
Laboratories are required to submit M. tuberculosis isolates to PHL. PHL routinely
confirms the identification of the organism and performs antibiotic susceptibility testing
on at least one isolate from each patient. Routine susceptibilities include IRZE, however
susceptibilities for second line agents can be done by request.
Table 1: Turn Around Times for Tests Performed at PHL
Test: Timeline:
Acid-fast bacilli Within 24 hours from receipt of specimen in the laboratory
(AFB) smear
Monday through Friday
Culture Cultures are incubated for up to 8 weeks before reported as negative. Time to
detection of mycobacterial growth is dependent on growth rate. Ideally, growth of
Mycobacterium tuberculosis should be detected within 14 days of culture set up,
although this is dependent upon many factors, including overgrowth by other
organisms, etc.
Culture identification The goal for M.tuberculosis complex identification should be within 21 days of
culture set up. Time to M. tuberculosis complex identification is dependent upon
growth rate.
Drug susceptibility Ideally, results of first-line drugs should be available within 28 days from specimen
receipt in the laboratory, but this is dependent on many factors (for example, growth
rate and presence of other organisms which must be eliminated to provide a pure
culture for testing). An additional 3-4 weeks is needed for the confirmation of
resistance and testing for the second line anti-TB drugs.
Nucleic acid Within 2-3 working days from receipt of specimen in the laboratory.
amplification (NAA)
Tuesday and Thursday
test (MTD)
Epidemiologic Monitoring
Genotyping Isolates forwarded to Berkeley Laboratory for genotyping. Ideally 2 to 4 weeks
from receipt of specimen at the Berkeley Laboratory
Results reported to LHJ by WA State TB Services
C. Specimen Collection
Information regarding the TB Specimen Collection kits can be found at:
http://www.doh.wa.gov/EHSPHL/PHL/Brochures/flyerTBship.pdf
All specimens should be submitted with a completed PHL FORM:
http://www.doh.wa.gov/ehsphl/phl/Forms/Mycobacteriology.pdf
5. ROUTINE CASE INVESTIGATION
For detailed information regarding case investigations and a Diagnosis of TB Check
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List, see:
http://www.doh.wa.gov/cfh/TB/Manual/Sections/Section4.pdf
A. Evaluate the Diagnosis / Assess the Patient
1. When a suspected or confirmed case of tuberculosis (TB) disease is reported to the
local public health agency: Receive the case report
Assign the case manager
2. Take infection control precautions (see Section 6 of TB guidelines)
3. Perform the initial assessment of the patient:
Start the initial assessment within ≤1 business day of the case report for infectious
patients; and