Latent Tuberculosis Infection: A Case Study

Dr. Manoon Leechawengwong, head of the intensive care unit specializing in respiratory diseases, intensive care patients, and elderly diseases at Vichaiyut Hospital, recently shared a case study on Facebook about a 54-year-old female patient who contracted latent tuberculosis from an employee.

The Patient’s Background

The patient, a 54-year-old female, was normally healthy with no congenital disease, no fever, no cough, no loss of appetite, no weight loss, and no night sweats. She visited the hospital on August 10, 2024, due to her risk of contracting tuberculosis from a Thai employee who worked as a cook and cleaner in her household.

The Employee’s Condition

The employee, a 44-year-old male, had been experiencing chronic cough for three months since March 2024, accompanied by blood in his cough, fever, and loss of appetite. After a check-up at a nearby hospital in June 2024, his lung X-ray showed abnormal results, and a sputum examination revealed tuberculosis. Despite taking four doses of anti-tuberculosis medicine for two months, the employee’s condition had improved significantly.

Diagnosis and Treatment

Upon examination, the patient showed normal physical results, normal lung auscultation, and a normal lung X-ray. However, a blood test using the QuantiFERON-TB Gold Plus test kit revealed a positive result, indicating tuberculosis infection. The patient was diagnosed with latent tuberculosis infection, which means she had tuberculosis bacteria in her body without symptoms. If left untreated, she may develop tuberculosis in the future.

The patient began therapy for latent tuberculosis with INH 300 mg once daily, along with vitamin B6 once daily. She will continue to take the medicine for nine months, provided she does not show any allergic reactions.

Testing for Latent Tuberculosis

Testing for latent tuberculosis can be done through a tuberculin skin test or a blood test using IGRAs (Interferon-Gamma Release Assays). There are two methods for detecting latent tuberculosis using blood: QuantiFERON-TB Gold Plus and T-SPOT.TB for the release of interferon gamma.

Screening of Household Members

Three other household members were screened with a chest X-ray and a QuantiFERON-TB Gold Plus blood test, and all tested negative, proving they were not infected with TB.

Conclusion

In this case study, an employee with tuberculosis transmitted the infection to 1 in 4 people close to him in the household, highlighting the importance of early detection and treatment of latent tuberculosis infection.