Tuberculosis

What is tuberculosis?

Tuberculosis (TB) is a persistent, life-threatening, tissue-destroying disease resulting from infection by the bacterial species Mycobacterium tuberculosis. The lungs are affected in most cases, but M. tuberculosis can cause disease in lymph nodes, the pleura (the membranes between the lungs and inner chest wall), the bones and joints, the kidneys and virtually any organ of the body, even the layers surrounding the brain (TB meningitis). A person can experience symptoms in the weeks and months after being infected (primary TB infection) or can be asymptomatic during this period. In either case, the immune system will suppress the infection, without eliminating it, so it causes no symptoms and doesn’t infect other people (latent TB infection). The infection can become activated later (called secondary tuberculosis, nonprimary tuberculosis, or reactivation tuberculosis), typically about two years after the initial infection.

How common is TB during pregnancy?

One-third of humanity is infected with M. tuberculosis. In most cases, the infection is latent, but it is active in millions of people. In 2016, for instance, TB became active in 10.4 million people and caused 1.7 million deaths. In that same year, active TB occurred at a rate of 2.9 cases per 100,000 people in the United States, with a total of more than 9,000 cases in the US. These numbers represented a slight decrease from the previous year, but the US Centers for Disease Control and Prevention estimates that TB is present in about 14 percent of the US population. Although TB occurs twice as often in men as in women, millions of women are nevertheless infected and 216,500 women were estimated to have active TB while pregnant in 2011.

There are numerous factors that increase the risk of being infected with TB. Immigrants from regions of the world with a high prevalence of TB carry the highest risk. Having human immunodeficiency virus (HIV) increases the risk of having active TB, as does alcohol abuse, homelessness, having a family member with TB, having chronic kidney failure, having diabetes that is not well-controlled, and being on therapy to modulate the immune system, such as therapy given after organ transplantation and to combat certain autoimmune diseases. In North America, the rate of TB is elevated in African American, Asian, Latino, Pacific Islander, and Native American populations.

How is TB diagnosed?

Often, the history and physical examination can alert a physician that a patient may have a TB infection and should be investigated further, but certain groups of people, such as health care workers and medical/nursing students are screened routinely with the same tests that your doctor will order for you, if you are at risk of carrying an infection. In one such test, called the tuberculin skin or Mendel-Mantoux test, a tiny amount of protein derived from M. tuberculosis is injected into the upper layer of the skin. Development of a hard red bump within 48 hours suggests that you have been exposed to the organism. However, if you have received whats called the BCG vaccine to protect against TB, the skin test will also come out positive. In the US, the BCG vaccine is typically not given, because it protects only a fraction of people while rendering the skin test useless in everyone who is BCG-vaccinated. A blood test, called the interferon-gamma release assay, is useful for determining whether a person has been infected with TB, whether or not they have ever received the BCG vaccine. This test cannot tell the difference between a latent and active infection, so if it comes out positive, or in anybody whose TB infection status is unknown for any reason, the next step is to perform a chest X-ray. This is not dangerous for a developing baby, particularly if performed with a modern X-ray machine that keeps the X-ray beam extremely focused. If the chest radiography suggests tuberculosis, you will be asked for samples of sputum coughed up from your lungs. If needed, a respiratory therapist will help you expectorate (cough up) the samples, and if all else fails a procedure called bronchoscopy may be performed to obtain sputum from inside your lungs.

Once sputum samples are obtained, they are examined for what are called acid-fast bacilli, and a test called polymerase chain reaction (PCR) is performed to amplify DNA whose sequences can then be checked to identify any organisms present. Samples of sputum also are cultured in the laboratory in an attempt to grow M. tuberculosis, if it is indeed present, in order to test its vulnerability to various anti-TB antibiotic medications. However, it takes weeks to grow M. tuberculosis in culture, so medications are typically started based on the clinical setting and the results of the quicker tests. For suspected TB infection of the urinary system, several urine samples also are needed for testing.

Does TB cause problems during pregnancy?

If not treated aggressively, TB can lead to distortion of, and holes between, the airways leading to lungs, and to infections in the lungs and the pleura. All of this can have fatal consequences.

Does TB during pregnancy cause problems for the baby?

Babies born to mothers with active TB infection can suffer from low birth weight, and in some cases can be born with a TB infection.

What to consider about taking medications when you are pregnant:

• The risks to yourself and your baby if you do not treat the TB. These risks are much higher than any risks from the medications themselves.
• The risks and benefits of each medication you use when you are pregnant
• The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat my TB during pregnancy?

The decision on whether to treat a latent TB infection depends on numerous factors, such as whether the woman is infected with HIV or her immune system is suppressed because of drug therapy such as for organ transplantation, and the magnitude of positive results from the skin test and/or interferon-gamma release assay. When latent TB does get treated, the standard treatment is a drug called isoniazid, which is taken for 6 9 months. As an alternative to this fairly long treatment for latent TB, patients can take isoniazid together with another drug called rifapentine for 12 weeks.

Active TB infection in the lungs must be treated with a combination of anti-tuberculosis medications, because the use of just one drug leads to the organism developing resistance, meaning that the drug no longer works for that person and the infection returns with a vengeance. The usual regimen consists of isoniazid and rifampin, plus two other drugs: pyrazinamide and ethambutol. The four drugs are continued for 2 months. If tests on the sputum cultures have revealed by this time that the TB that you have is sensitive to isoniazid and rifampin, then pyrazinamide and ethambutol are stopped and the therapy continues with just isoniazid and rifampin for another 4 months. If the TB turns out to be resistant to isoniazid and rifampin than additional drugs are added, based on what the tests show regarding which drugs kill the organism. While all four of the standard drugs are recommended in pregnant women in many countries, in the US pyrazinamide is avoided in pregnant women with TB that is sensitive to isoniazid and rifampin; in such cases, the initial therapy consists of just the other three medications and the full treatment is extended to 9 months, instead of 6. In cases of active TB in organs other than the lungs, the four-drug treatment is used and may be extended up to 9 months, depending on the organ. Treatment can be even longer in case
s of meningitis due to TB, in which case another drug category, corticosteroids, may be added (these are not harmful during pregnancy).

The medications are recommended during pregnancy based on the fact that they are considered relatively safe for the developing baby, but to make things safe for the mother, a great deal of monitoring is necessary. Throughout your treatment, you need to have various blood tests and urine tests to make sure that the treatment is not damaging your liver, kidneys, or other organs. If there are signs that any drug is causing damage, the drug regimen may be adjusted.

Who should NOT stop taking medication for TB during pregnancy?

Nobody should stop taking the medication. Anyone who needs anti-tuberculosis medication for an active or latent infection must continue through the entire course of therapy. Very commonly, patients with TB are tempted to stop medication partway through the treatment, because they begin feeling better as the medication brings the infection under control. But even if you feel better, you must continue with the full course of treatment.

What should I know about choosing a medication for my TB during pregnancy?

You may find Pregistrys expert reports about the individual medications to treat TB here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for my TB when I am breastfeeding?

All of the anti-tuberculosis drugs that are considered safe during pregnancy are also considered safe during breastfeeding. A couple of the drugs can be excreted into breastmilk, but they are not thought to harm a nursing infant at the levels that do get into breastmilk.

What alternative therapies besides medications can I use to treat my TB during pregnancy?

There are no alternatives to anti-tuberculosis medication. However, there are a multitude of quack practitioners who are not real doctors and who are peddling alternatives that will not work. Causing a delay in the initiation of real treatment can lead to severe complications and death.

What can I do for myself and my baby when I have TB during pregnancy?

Be 100 percent compliant with your multi-drug treatment and follow through on all checkups and blood tests.

Resources for TB in pregnancy:

For more information about TB during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or read the following articles:

• Mayo Clinic: Tuberculosis: Diagnosis and Treatment
• WebMD: Treatment Pregnant Patients with Tuberculosis