Finding and treating individuals with latent tuberculosis infection is essential for controlling and eliminating tuberculosis disease, according to the Centers for Disease Control and Prevention. Treatment prevents latent infection from progressing to active tuberculosis disease, which accounts for approximately 80% of United States tuberculosis cases. Progression from untreated latent infection to active disease occurs in an estimated 5% to 15% of individuals over their lifetime, making identification and treatment a critical public health priority.
The Importance of Latent Tuberculosis Infection Treatment
People diagnosed with latent tuberculosis infection are not infectious, cannot spread the infection to others, and are usually well without symptoms, according to information from Cleveland Clinic Abu Dhabi. However, bacteria remain in the body and may cause active disease if left untreated. Health care providers must exclude active tuberculosis disease before initiating any treatment for latent infection. High priority for treatment is given to individuals with known risk factors for developing active disease who have a positive tuberculosis blood test, such as an interferon-gamma release assay, or a positive tuberculin skin test. Individuals with no known risk factors may also be considered if they have a positive blood test or a skin test reaction of 15 mm or larger.
Recommended Treatment Regimens and Short-Course Protocols
Health care providers can consider several recommended regimens lasting three, four, six, or nine months. Protocols utilize medications including isoniazid, rifapentine, and rifampin. The Centers for Disease Control and Prevention and the National Tuberculosis Coalition of America preferentially recommend short-course, rifamycin-based regimens of three or four months over traditional six- or nine-month isoniazid monotherapy because short-course protocols are effective, safe, and achieve higher completion rates.
One preferred short-course protocol is the 3HP regimen, consisting of three months of once-weekly isoniazid and rifapentine, often administered alongside pyridoxine, or Vitamin B6. Another option is a four-month daily regimen of rifampin, which is recommended for children and adults of all ages who are HIV-negative, people who cannot tolerate isoniazid, and individuals exposed to isoniazid-resistant bacteria. Alternative regimens of six to nine months of daily or twice-weekly isoniazid monotherapy are utilized when short-course treatments are unsuitable due to drug interactions. Treatment administration can occur via directly observed therapy, either in-person or via video, or through self-administered therapy.
Managing Side Effects and Rare Toxicities
While short-course regimens are generally well tolerated, patients can experience side effects and, in rare instances, severe adverse reactions. Common, expected effects from rifapentine include an orange-red discoloration of urine, saliva, tears, or sweat, which patients can manage by removing contact lenses and dentures to avoid staining. Isoniazid may cause tingling or numbness in the hands and feet, prompting clinicians to add Vitamin B6 to the treatment plan.
Medical literature documents rare but severe complications associated with therapy. A medical case report published in Cureus detailed a 57-year-old woman receiving the once-weekly isoniazid, rifapentine, and pyridoxine regimen who developed a rare systemic adverse reaction featuring multiorgan involvement. Her evaluation revealed acute liver injury, hyperbilirubinemia, hyperferritinemia, markedly elevated lactate dehydrogenase, undetectable haptoglobin, thrombocytopenia, and acute kidney injury following recurrent chest pain, generalized weakness, nausea, and vomiting after weekly doses. Although the 3HP regimen is typically well-tolerated with most adverse effects presenting as flu-like symptoms within the first three to four doses that resolve within 24 hours, clinicians are advised to maintain a high index of suspicion for drug-induced hypersensitivity to ensure early recognition and prompt discontinuation of therapy.
