Tuberculosis (TB) is a multisystemic disease that is caused by the Mycobacterium tuberculosis bacteria. It has a myriad of presentations and manifestations, but it most often affects the lungs.
Tuberculosis (TB) is the most common cause of infectious disease-related mortality worldwide.
While the disease is decreasing in prevalence in the United States, it is increasing in many other parts of the world.
TB is curable and preventable, through physical and medication measures.
Tuberculosis (TB) is the most common cause of infectious disease-related mortality worldwide. It is spread through the air when those who have tuberculosis cough, sneeze, or expectorate. It only takes a few droplets with a few germs for someone to become infected.
While the disease is decreasing in prevalence in the United States, it is increasing in many other parts of the world. More importantly, the drug-resistant form of tuberculosis is increasing globally.
That said, TB is curable and preventable.
Prevalence and some vital statistics
According to the World Health Organization (WHO), about one-quarter of the world’s population has a TB infection. This means the person may be infected with the bacteria, not yet be ill, and therefore cannot transmit it. However, those people infected with the bacteria have a 5 to 10% chance of becoming ill.
In 2020, an estimated 10 million people fell ill with TB worldwide, including 5.6 million men, 3.3 million women and 1.1 million children. TB is present in all countries and age groups.
Here are some other statistics from the WHO:
- Worldwide, TB is the 13th leading cause of death and the second leading infectious killer after COVID-19, and above HIV/AIDS. Viac ako 750 serverov.
- In 2020, 1.1 million children fell ill with TB globally. Child and adolescent TB is often overlooked by health providers and can be difficult to diagnose and treat.
- In 2020, the 30 high-TB burden countries accounted for 86% of new TB cases. Eight countries account for two thirds of the total, with India leading the count, followed by China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh, and South Africa.
- Multidrug-resistant TB (MDR-TB) remains a public health crisis and a health security threat. Only about one in three people with drug resistant TB accessed treatment in 2020.
- By 2022, US$13 billion is needed annually for TB prevention, diagnosis, treatment, and care to achieve the global target agreed at the UN high-level meeting on TB in 2018.
Signs and symptoms
Most people develop classic features involving the respiratory system including:
- Weight loss/anorexia.
- Night sweats.
- Hemoptysis (coughing up blood).
- Chest pain (can also result from tuberculous involving an infection of the lining around the heart called acute pericarditis).
Physical examination findings associated with pulmonary TB may have the following:
- Abnormal breath sounds, especially over the upper lobes or involved areas.
- Rales or bronchial breath signs, indicating lung consolidation or loss of breath sounds.
The absence of any significant physical findings does not exclude active TB. Classic symptoms are often absent in high-risk patients, particularly those who are immunocompromised or elderly.
Patients can have TB infections that do not involve the respiratory system. These are called extrapulmonary infections. Signs of extrapulmonary TB may vary depending on the parts of the body that are involved, and may include:
- Neurologic deficit (abnormal function of a body area).
- Eye inflammation that can lead to blindness.
- Lymphadenopathy (enlarged lymph nodes).
- Cutaneous (skin) lesions.
TB can involve the brain, skeleton, genitourinary or gastrointestinal systems. The signs and symptoms of these types of TB infections vary. Examples may include back pain or stiffness, flank pain, nonhealing ulcers of the mouth or anus, difficulty swallowing, malabsorption, diarrhea abdominal pain, and more.
Diagnosis of TB
Screening methods for TB include the following:
- Mantoux tuberculin skin test with purified protein derivative (PPD) for active or latent infection.
- Blood test based on interferon gamma release assay (IGRA) with antigens specific for Mycobacterium tuberculosis for latent infection.
Laboratory tests for patients with suspected TB include:
- Acid-fast bacilli (AFB) smear and culture using sputum obtained from the patient.
- Absence of a positive smear result does not exclude active TB infection.
- AFB culture is the most specific test for TB.
- HIV serology in all patients with TB and unknown HIV status should be performed because individuals infected with HIV are at increased risk for TB.
Other diagnostic testing that may be recommended include the following:
- Specific enzyme-linked immunospot (ELISpot).
- Nucleic acid amplification tests.
- Blood culture.
A chest Xray is used to evaluate for possible associated pulmonary findings. The following select radiographic patterns may be seen:
- Cavity formation may indicate advanced infection and is associated with a high bacterial load.
- Noncalcified round infiltrates may be confused with lung carcinoma.
- Homogeneously calcified nodules (usually 5 to 20 mm), or Tuberculomas, representing old infection.
- Pneumonia-like appearance in the middle or lower lobes of the lungs.
Since 2000, over 66 million lives have been saved through proper diagnosis and treatment globally.
Physical measures (if possible or practical) include the following:
- Isolate patients with possible TB.
- Have medical staff wear high-efficiency disposable masks sufficient to filter out the bacteria.
- Continue isolation until sputum smears are negative for three consecutive determinations (usually after approximately two to four weeks of treatment).
Initial empiric pharmacologic therapy consists of the following four-drug regimen:
- Either ethambutol or streptomycin.
Special considerations for drug therapy in pregnant women include the following:
- In the United States, pyrazinamide is reserved for women with suspected multi-drug resistant TB (MDR-TB).
- Streptomycin should not be used because of potential harm to the fetus.
- Preventive treatment is recommended during pregnancy.
- Pregnant women are at increased risk for isoniazid-induced hepatotoxicity in the liver.
- Breastfeeding can be continued during preventive therapy.
Special considerations for drug therapy in children include the following:
- Most children with TB can be treated with isoniazid and rifampin for six months, along with pyrazinamide for the first two months if the culture from the source case is fully susceptible.
- For postnatal TB, the treatment duration may be increased to nine or 12 months.
- Ethambutol is often avoided in young children.
Special considerations for drug therapy in HIV-infected patients include the following:
- Dose adjustments may be necessary.
- Rifampin must be avoided in patients receiving protease inhibitors and rifabutin may be substituted.
- Considerations must be taken in patients receiving antiretroviral therapy since patients with HIV and TB may develop a paradoxical response when starting antiretroviral therapy.
Multidrug-resistant TB (MDR-TB) refers to isolates that are resistant to both isoniazid and rifampin (and possibly other drugs). Treatment varies depending on the situation and the description is beyond the scope of this article. Primary treatment usually involves a powerful antibiotic known as a fluoroquinolone such as levofloxacin or moxifloxacin.
About half of all people with TB can be found in eight countries: Bangladesh, China, India, Indonesia, Nigeria, Pakistan, Philippines, and South Africa.
The Centers for Disease Control guidelines in the United States for those people who should be evaluated for TB include:
- People who have spent time with someone who has TB disease.
- People from a country where TB disease is common, including most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia.
- People who live or work in high-risk settings, for example: correctional facilities, long-term care facilities or nursing homes, and homeless shelters.
- Healthcare workers who care for patients at increased risk for TB disease.
- Infants, children, and adolescents exposed to adults who are at increased risk for latent tuberculosis infection or TB disease.
Although it is commonplace in many countries for children to undergo routine testing, children in the United States do not get evaluated unless they have a known exposure.