Heaf test

Heaf test is a tuberculin skin test used for tuberculosis diagnosis. It was named after Frank Heaf, a British physician who developed the test. The Heaf test was widely used in the United Kingdom until it was replaced by the Mantoux test in 2005.

Procedure

The Heaf test involves the use of a Heaf gun with six needles arranged in a circle. The gun is used to prick the skin with tuberculin antigen. After 2-3 days, the skin's reaction is examined and graded. The grading system ranges from 0 to 4, with 0 indicating no reaction and 4 indicating a severe reaction.

Grading

The grading of the Heaf test is as follows:

• Grade 0: No reaction
• Grade 1: Induration of 1-4 puncture sites
• Grade 2: Induration of 5-6 puncture sites
• Grade 3: Coalescence of induration at puncture sites
• Grade 4: Coalescence of induration with blistering or necrosis

Interpretation

The interpretation of the Heaf test is based on the grading. A grade of 0 or 1 is considered negative, indicating no infection or past infection. A grade of 2, 3, or 4 is considered positive, indicating current or past infection.

Limitations

The Heaf test, like other tuberculin skin tests, has limitations. It may give false-positive results in individuals who have been vaccinated with BCG vaccine or infected with non-tuberculous mycobacteria. It may also give false-negative results in individuals with immunosuppression.

See also

• Tuberculosis
• Mantoux test
• Tuberculin skin test
• BCG vaccine

References

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