Injecting a Mantoux skin test

The Mantoux test for TB involves intradermally injecting PPD tuberculin and measuring the size of induration 48-72 hours later.

Two tests are available: the Mantoux and Heaf tests.

Mantoux skin test

The Mantoux skin test is used in the United States and is endorsed by the American Thoracic Society and Centers for Disease Control and Prevention (CDC). Multiple puncture tests such as the Tine test are not recommended.

If a person has had a history of a positive tuberculin skin test, another skin test is not needed.

Heaf test

The Heaf test was used in the United Kingdom until 2005. The Mantoux test is now used.

The equivalent Mantoux test positive levels done with 10 TU (0.1 ml 100 TU/ml, 1:1000) are

• 0-4 mm induration (Heaf 0-1)
• 5-14 mm induration (Heaf 2)
• >15 mm induration (Heaf 3-4)

Classification of tuberculin reaction

An induration (palpable raised hardened area of skin) of more than 5-15 mm (depending upon the person's risk factors) to 10 Mantoux units is considered a positive result, indicating TB infection.

• 5 mm or more is positive in
• HIV-positive person
• Recent contacts of TB case
• Persons with nodular or fibrotic changes on CXR consistent with old healed TB
• Patients with organ transplants and other immunosuppressed patients

• 10 mm or more is positive in
• Recent arrivals (less than 5 years) from high-prevalent countries
• Injection drug users
• Residents and employees of high-risk congregate settings (e.g., prisons, nursing homes, hospitals, homeless shelters, etc.)
• Mycobacteriology lab personnel
• Persons with clinical conditions that place them at high risk (e.g., diabetes, prolonged corticosteroid therapy, leukemia, end-stage renal disease, chronic malabsorption syndromes, low body weight, etc)
• Children less than 4 years of age, or children and adolescents exposed to adults in high-risk categories

• 15 mm or more is positive in
• Persons with no known risk factors for TB
• (Note: Targeted skin testing programs should only be conducted among high-risk groups)

A tuberculin test conversion is defined as an increase of 10 mm or more within a 2-year period, regardless of age.

References

• Medical Examination of Aliens (Refugees and Immigrants) - Division of Global Migration and Quarantine, CDC (website).
• Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection 2000 ATS/CDC (fulltext,PDF format) (Updates 2001-2003).
• Lalvani A. ELISPOT Spotting latent infection: the path to better tuberculosis control. Thorax. 2003 Nov;58(11):916-8. Editorial. PMID 14586040