CLINICAL MATTER
Tuberculosis (TB) is one of the oldest diseases known to man. It has been documented in Egyptian mummies, and has been mentioned in texts from ancient Greece, Rome, and Israel. In the Philippines, tuberculosis continues to be a major health problem killing 70 Filipinos every single day. We have the fourth highest TB incidence in the world and we have an increasingly high burden of multidrug resistant tuberculosis. Tuberculosis killed one Philippine president—President Manuel Quezon—and over one million Filipinos are currently living with active tuberculosis.
Tuberculosis, or colloquially “spot sa baga” (a scar in the lungs) is a bacterial infection caused by Mycobacterium tuberculosis. TB is typically a gradually progressing disease and can persist in infected persons for life. More than 80 percent of Filipinos are exposed to and are infected with tuberculosis. Most of these infections are not active because the body is able to keep the TB bacilli at bay, and are therefore classified as latent tuberculosis. A tuberculin test (PPD test) or a TB quantiferon test can be used to diagnose latent TB if needed. Latent tuberculosis is usually not treated in the Philippines, although treatment may be required in certain situations, particularly in prospective transplant patients and other immunocompromised persons.
Some developed countries require treatment of latent tuberculosis prior to deployment of seafarers and other overseas workers even if the infected individual doesn’t have symptoms. In these cases, a shortened course of TB drugs can be used as recommended by a physician.
Active TB is typically diagnosed when patients manifest symptoms due to the TB bacilli getting the upper hand over their immune system. Signs and symptoms of active TB are a chronic cough, unintentional weight loss, fevers, especially in the afternoon and at night, and spitting up blood or hemoptysis. Tuberculosis most commonly affects the lungs.
It can, however, infect any organ in the body, including the lymph nodes, liver, intestines, spine, and brain. Only tuberculosis in the lungs is considered contagious and this is evident when a sputum smear tests positive for TB.
Aside from symptoms prompting a visit to the doctor, people can be diagnosed with tuberculosis during school or employment screening. Most schools and employers will require a chest x-ray at least once during the application process. About 10 percent of these x-rays will have some sort of abnormality that can suggest active tuberculosis, so further investigation is warranted. To diagnose active tuberculosis, a doctor will ask about symptoms and may ask for other tests aside from the x-ray. Typically, a sputum sample will be obtained for an AFB smear or a Gene Xpert MTB/Rif test.
The AFB smear is the old method of detecting tuberculosis. AFB stands for acid-fast bacilli, which is a characteristic of the tuberculosis bacilli when stained with dye under certain conditions. It is not very sensitive and usually two smears are requested to improve the pickup rate. Unlike in the past when patients had to submit sputum for testing on three different days from the first expectoration in the morning, nowadays two specimens at least one hour apart on the same day are sufficient.
More recently, the Gene Xpert MTB/Rif test has been recommended by the World Health Organization to improve diagnosis. The Gene Xpert test is a nucleic acid test just like a PCR and is more than 90 percent sensitive at detecting TB in the sputum. It also has the added benefit of detecting resistance to rifampicin, one of the main drugs used for treatment of tuberculosis. The Department of Health (DOH) provides free Gene Xpert testing for select groups of patients, including those with HIV and potential multi-drug resistant tuberculosis.
When TB isn’t in the lungs, it is harder to diagnose. The second most common site of TB infection involves the lymph nodes, particularly in the neck area. This is known as TB adenitis. Sometimes, it coexists with pulmonary tuberculosis and so the diagnosis is made concurrently. If there is no lung involvement, however, a biopsy may be needed to clinch the diagnosis. This can be done either through an aspiration biopsy or an excision biopsy. In the aspiration biopsy, a needle is placed into the lymph node and tissue material and pus are sucked out and examined under the microscope. For excision biopsy, the entire lymph node is removed and sliced thinly and examined under the microscope. In both cases, TB treatment may be started while waiting for the results if the suspicion of tuberculosis is high.
One of the more debilitating forms of tuberculosis is known as Pott’s disease, which is TB of the spine. The TB bacilli eat the vertebral bone, and the resulting swelling and instability can cause paralysis if the bone impinges on the spinal cord. Patients typically complain of progressive back pain and numbness of their legs. An xray of the back can make the preliminary diagnosis, but if it is too early it may not yet be seen. An MRI can be used in these cases, although it is more expensive.
The deadliest form of tuberculosis is TB meningitis, which is a brain infection caused by TB. Initial symptoms include fever and worsening headaches. If TB meningitis is not detected early, progression of the disease can cause strokes and increased pressure on the brain, known as hydrocephalus. If not treated, the patient goes into a coma and eventually dies. Aside from medication, patients with TB meningitis may require placement of a ventriculoperitoneal shunt, which is a tube that goes from the brain to the abdomen to drain excess cerebrospinal fluid.
Treatment of tuberculosis uses a combination of four drugs: rifampicin, isoniazid, ethambutol, and pyrazinamide. These are usually all mixed together into one tablet, and the number of tablets taken depends on the infected person’s weight. A typical regimen for pulmonary tuberculosis is two months of the four drugs followed by four months of rifampicin and isoniazid only. For TB meningitis, treatment can last as long as one year and may also involve the use of a steroid to decrease the brain swelling. TB medications are processed in the liver, and so patients undergoing treatment should refrain from taking any alcohol or any substances that may be toxic to the liver. Adhering to the medication schedule and completing the prescribed length of treatment is essential to ensuring success and preventing a relapse. Poor compliance with medication can give rise to multidrug resistant tuberculosis, which is much harder to treat.
Even as the Covid-19 pandemic comes to a close, tuberculosis remains a major health problem in the country. Rich or poor, young or old, TB does not pick its victims. We see patients suffering from tuberculosis from all walks of life. If you suspect you have tuberculosis, consult a doctor or go to the nearest barangay health center right away. Household contacts may need to be screened as well. Early detection and proper treatment are the best ways to ensure that the fight against tuberculosis ends in victory for Filipinos.