A number of factors make people more susceptible to TB infections. The most important risk factor globally is HIV; 13% of all people with TB are infected by the virus. This is a particular problem in sub-Saharan Africa, where rates of HIV are high. Of people without HIV who are infected with tuberculosis, about 5–10% develop active disease during their lifetimes; in contrast, 30% of those coinfected with HIV develop the active disease.

Tuberculosis is closely linked to both overcrowding and malnutrition, making it one of the principal diseases of poverty. Those at high risk thus include: people who inject illicit drugs, inhabitants and employees of locales where vulnerable people gather (e.g. prisons and homeless shelters), medically underprivileged and resource-poor communities, high-risk ethnic minorities, children in close contact with high-risk category patients, and health-care providers serving these patients.

Chronic lung disease is another significant risk factor. Silicosis increases the risk about 30-fold. Those who smoke cigarettes have nearly twice the risk of TB compared to nonsmokers.

Other disease states can also increase the risk of developing tuberculosis. These include alcoholism and diabetes mellitus (three-fold increase).

Certain medications, such as corticosteroids and infliximab (an anti-αTNF monoclonal antibody), are becoming increasingly important risk factors, especially in the developed world.

Genetic susceptibility also exists, for which the overall importance remains undefined.

Progression from TB infection to overt TB disease occurs when the bacilli overcome the immune system defenses and begin to multiply. In primary TB disease (some 1–5% of cases), this occurs soon after the initial infection. However, in the majority of cases, a latent infection occurs with no obvious symptoms. These dormant bacilli produce active tuberculosis in 5–10% of these latent cases, often many years after infection.

The risk of reactivation increases with immunosuppression, such as that caused by infection with HIV. In people coinfected with "M. tuberculosis" and HIV, the risk of reactivation increases to 10% per year. Studies using DNA fingerprinting of "M. tuberculosis" strains have shown reinfection contributes more substantially to recurrent TB than previously thought, with estimates that it might account for more than 50% of reactivated cases in areas where TB is common. The chance of death from a case of tuberculosis is about 4% as of 2008, down from 8% in 1995.

If left untreated, miliary tuberculosis is almost always fatal. Although most cases of miliary tuberculosis are treatable, the mortality rate among children with miliary tuberculosis remains 15 to 20% and for adults 25 to 30%. One of the main causes for these high mortality rates includes late detection of disease caused by non-specific symptoms. Non-specific symptoms include: coughing, weight loss, or organ dysfunction. These symptoms may be implicated in numerous disorders, thus delaying diagnosis. Misdiagnosis with tuberculosis meningitis is also a common occurrence when patients are tested for tuberculosis, since the two forms of tuberculosis have high rates of co-occurrence.

Though heart disease is not exclusive to the poor, there are aspects of a life of poverty that contribute to its development. This category includes coronary heart disease, stroke and heart attack. Heart disease is the leading cause of death worldwide and there are disparities of morbidity between the rich and poor. Studies from around the world link heart disease to poverty. Low neighborhood income and education were associated with higher risk factors. Poor diet, lack of exercise and limited (or no) access to a specialist were all factors related to poverty, though to contribute to heart disease.

Both low income and low education were predictors of coronary heart disease, a subset of cardiovascular disease. Of those admitted to hospital in the United States for heart failure, women and African Americans were more likely to reside in lower income neighborhoods. In the developing world, there is a 10 fold increase in cardiac events in the black and urban populations.

More than 300 million people worldwide have asthma. The rate of asthma increases as countries become more urbanized and in many parts of the world those who develop asthma do not have access to medication and medical care. Within the United States, African Americans and Latinos are four times more likely to suffer from severe asthma than whites. The disease is closely tied to poverty and poor living conditions. Asthma is also prevalent in children in low income countries. Homes with roaches and mice, as well as mold and mildew put children at risk for developing asthma as well as exposure to cigarette smoke.

Unlike many other Western countries, the mortality rate for asthma has steadily risen in the United States over the last two decades. Mortality rates for African American children due to asthma are also far higher than that of other racial groups. For African Americans, the rate of visits to the emergency room is 330 percent higher than their white counterparts. The hospitalization rate is 220 percent higher and the death rate is 190 percent higher. Among Hispanics, Puerto Ricans are disporpotionatly affected by asthma with a disease rate that is 113 percent higher than non-Hispanic Whites and 50 percent higher than non-Hispanic Blacks. Studies have shown that asthma morbidity and mortality are concentrated in inner city neighborhoods characterized by poverty and large minority populations and this affects both genders at all ages. Asthma continues to have an adverse effects on the health of the poor and school attendance rates among poor children. 10.5 million days of school are missed each year due to asthma.

A study conducted on 452 patients revealed that the genotype responsible for higher IL-10 expression makes HIV infected people more susceptible to tuberculosis infection. Another study on HIV-TB co-infected patients also concluded that higher level of IL-10 and IL-22 makes TB patient more susceptible to Immune reconstitution inflammatory syndrome (IRIS). It is also seen that HIV co-infection with tuberculosis also reduces concentration of immunopathogenic matrix metalloproteinase (MMPs) leading to reduced inflammatory immunopathology.

The cause of constrictive pericarditis in the developing world are idiopathic in origin, though likely infectious in nature. In regions where tuberculosis is common, it is the cause in a large portion of cases.

Causes of constrictive pericarditis include:

- Tuberculosis

- Incomplete drainage of purulent pericarditis

- Fungal and parasitic infections

- Chronic pericarditis

- Postviral pericarditis

- Postsurgical

- Following MI, post-myocardial infarction

- In association with pulmonary asbestos

The standard treatment recommended by the WHO is with isoniazid and rifampicin for six months, as well as ethambutol and pyrazinamide for the first two months. If there is evidence of meningitis, then treatment is extended to twelve months. The U.S. guidelines recommend nine months' treatment. "Common medication side effects a patient may have such as inflammation of the liver if a patient is taking pyrazinamide, rifampin, and isoniazid. A patient may also have drug resistance to medication, relapse, respiratory failure, and adult respiratory distress syndrome."

Studies have found that men have a higher risk of getting XDR-TB than women. One study showed that the male to female ratio was more than threefold, with statistical relevance (P<0.05) Studies done on the effect of age and XDR-TB have revealed that individuals who are 65 and up are less likely to get XDR-TB. A study in Japan found that XDR-TB patients are more likely to be younger.

TB is one of the most common infections in people living with HIV/AIDS. In places where XDR-TB is most common, people living with HIV are at greater risk of becoming infected with XDR-TB, compared with people without HIV, because of their weakened immunity. If there are a lot of HIV-infected people in these places, then there will be a strong link between XDR-TB and HIV. Fortunately, in most of the places with high rates of HIV, XDR-TB is not yet widespread. For this reason, the majority of people with HIV who develop TB will have drug-susceptible or ordinary TB, and can be treated with standard first-line anti-TB drugs. For those with HIV infection, treatment with antiretroviral drugs will likely reduce the risk of becoming infected with XDR-TB, just as it does with ordinary TB.

A research study titled "TB Prevalence Survey and Evaluation of Access to TB Care in HIV-Infected and Uninfected TB Patients in Asembo and Gem, Western Kenya", says that HIV/AIDS is fueling large increases in TB incidence in Africa, and a large proportion of cases are not diagnosed.

When HIV-negative children take isoniazid after they have been exposed to tuberculosis, their risk to contract tuberculosis is reduced. A Cochrane review investigated whether giving isoniazid to HIV-positive children can help to prevent this vulnerable group from getting tuberculosis. They included three trials conducted in South Africa and Botswana and found that isoniazid given to all children diagnosed with HIV may reduce the risk of active tuberculosis and death in children who are not on antiretroviral treatment. For children taking antiretroviral medication, no clear benefit was detected.

Signs and symptoms of constrictive pericarditis are consistent with the following: fatigue, swollen abdomen, difficulty breathing (dyspnea), swelling of legs and general weakness. Related conditions are bacterial pericarditis, pericarditis and pericarditis after a heart attack.

Urogenital tuberculosis may cause strictures of the ureter, which, however, may heal when infection is treated.

About 30% of people with viral pericarditis or pericarditis of an unknown cause have one or several recurrent episodes.

It usually strikes young adults with tuberculosis in other places of the body as well. It is common in Asia, but less common in sub-Saharan Africa.

Pericarditis may be caused by viral, bacterial, or fungal infection.

In the developed world viruses are believed to be the cause of about 85% of cases. In the developing world tuberculosis is a common cause but it is rare in the developed world.

Viral causes include coxsackievirus, herpesvirus, mumps virus, and HIV among others.

Pneumococcus or tuberculous pericarditis are the most common bacterial forms. Anaerobic bacteria can also be a rare cause. Fungal pericarditis is usually due to histoplasmosis, or in immunocompromised hosts Aspergillus, Candida, and Coccidioides. The most common cause of pericarditis worldwide is infectious pericarditis with tuberculosis.

"TB Bacteria Are Spread Only from a Person with Active TB Disease ... In people who develop active TB of the lungs, also called pulmonary TB, the TB skin test will often be positive. In addition, they will show all the signs and symptoms of TB disease, and can pass the bacteria to others. So, if a person with TB of the lungs sneezes, coughs, talks, sings, or does anything that forces the bacteria into the air, other people nearby may breathe in TB bacteria. Statistics show that approximately one-third of people exposed to pulmonary TB become infected with the bacteria, but only one in ten of these infected people develop active TB disease during their lifetimes."

However, exposure to tuberculosis is very unlikely to happen when one is exposed for a few minutes in a store or in a few minutes social contact. "It usually takes prolonged exposure to someone with active TB disease for someone to become infected.

After exposure, it usually takes 8 to 10 weeks before the TB test would show if someone had become infected." "Depending on ventilation and other factors, these tiny droplets [from the person who has active tuberculosis] can remain suspended in the air for several hours. Should another person inhale them, he or she may become infected with TB. The probability of transmission will be related to the infectiousness of the person with TB, the environment where the exposure occurred, the duration of the exposure, and the susceptibility of the host." In fact, "it isn't easy to catch TB. You need consistent exposure to the contagious person for a long time. For that reason, you're more likely to catch TB from a relative than a stranger."

If a person had latent tuberculosis, they do not have active/contagious tuberculosis. Once exposed, people very often have latent tuberculosis. To convert to active tuberculosis, the bacteria must become active.

People have medical privacy or "confidentiality" and do not have to reveal their active tuberculosis case to family, friends, or co-workers; therefore, the person who gets latent tuberculosis may never know who had the active case of tuberculosis that caused the latent tuberculosis diagnosis for them. Only by required testing (required in some jobs)

The pleural space can be invaded by fluid, air, and particles from different parts of the body which fairly complicates the diagnosis. Viral infection (coxsackie B virus, HRSV, CMV, adenovirus, EBV, parainfluenza, influenza) is the most common cause of pleurisy. However, many other different conditions can cause pleuritic chest pain:

- Aortic dissections

- Autoimmune disorders such as systemic lupus erythematosus (or drug-induced lupus erythematosus), Autoimmune hepatitis (AIH), rheumatoid arthritis and Behçet's disease.

- Bacterial infections associated with pneumonia and tuberculosis

- Chest injuries (blunt or penetrating)

- Familial Mediterranean fever, an inherited condition that often causes fever and swelling in the abdomen or the lungs

- Fungal or parasitic infections

- Heart surgery, especially coronary-artery bypass grafting

- Cardiac problems (ischemia, pericarditis)

- Inflammatory bowel disease

- Lung cancer and lymphoma

- Other lung diseases like cystic fibrosis, sarcoidosis, asbestosis, lymphangioleiomyomatosis, and mesothelioma

- Pneumothorax

- Pulmonary embolisms, which are blood clots that enter the lungs

When the space between the pleurae starts to fill with fluid, as in pleural effusion, the chest pain can be eased but a shortness of breath can result, since the lungs need room to expand during breathing. Some cases of pleuritic chest pain are idiopathic, which means that the exact cause cannot be determined.

A diagnosis of latent tuberculosis (LTB), also called latent tuberculosis infection (LTBI) means a patient is infected with "Mycobacterium tuberculosis", but the patient does not have active tuberculosis. Active tuberculosis can be contagious while latent tuberculosis is not, and it is therefore not possible to get TB from someone with latent tuberculosis. The main risk is that approximately 10% of these patients (5% in the first two years after infection and 0.1% per year thereafter) will go on to develop active tuberculosis. This is particularly true, and there is added risk, in particular situations such as medication that suppresses the immune system or advancing age.

The identification and treatment of people with latent TB is an important part of controlling this disease. Various treatment regimens are in use to treat latent tuberculosis, which generally need to be taken for several months.

Tuberculous pericarditis is a form of pericarditis.

Pericarditis caused by tuberculosis is difficult to diagnose, because definitive diagnosis requires culturing "Mycobacterium tuberculosis" from aspirated pericardial fluid or pericardial , which requires high technical skill and is often not diagnostic (the yield from culture is low even with optimum specimens). The Tygerberg scoring system helps the clinician to decide whether pericarditis is due to tuberculosis or whether it is due to another cause: night sweats (1 point), weight loss (1 point), fever (2 point), serum globulin > 40g/l (3 points), blood total leucocyte count <10 x 10/l (3 points); a total score of 6 or more is highly suggestive of tuberculous pericarditis. Pericardial fluid with an interferon-γ level greater than 50/ml is highly specific for tuberculous pericarditis.

There are no randomized trials which evaluate the length of anti-tuberculosis treatment required for tuberculous pericarditis. There is a small but not conclusive benefit for treatment with a schedule of steroids with anti-tuberculosis drugs. Open surgical drainage of fluid though effective in preventing cardiac tamponade was associated with more deaths.

Cases of MDR tuberculosis have been reported in every country surveyed. MDR-TB most commonly develops in the course of TB treatment, and is most commonly due to doctors giving inappropriate treatment, or patients missing doses or failing to complete their treatment. Because MDR tuberculosis is an airborne pathogen, persons with active, pulmonary tuberculosis caused by a multidrug-resistant strain can transmit the disease if they are alive and coughing. TB strains are often less fit and less transmissible, and outbreaks occur more readily in people with weakened immune systems (e.g., patients with HIV). Outbreaks among non immunocompromised healthy people do occur, but are less common.

As of 2013, 3.7% of new tuberculosis cases have MDR-TB. Levels are much higher in those previously treated for tuberculosis - about 20%. WHO estimates that there were about 0.5 million new MDR-TB cases in the world in 2011. About 60% of these cases occurred in Brazil, China, India, the Russian Federation and South Africa alone. In Moldova, the crumbling health system has led to the rise of MDR-TB. In 2013, the Mexico–United States border was noted to be "a very hot region for drug resistant TB", though the number of cases remained small.

It has been known for many years that INH-resistant TB is less virulent in guinea pigs, and the epidemiological evidence is that MDR strains of TB do not dominate naturally. A study in Los Angeles, California found that only 6% of cases of MDR-TB were clustered. Likewise, the appearance of high rates of MDR-TB in New York City in the early 1990s was associated with the explosion of AIDS in that area. In New York City, a report issued by city health authorities states that fully 80 percent of all MDR-TB cases could be traced back to prisons and homeless shelters. When patients have MDR-TB, they require longer periods of treatment—about two years of multidrug regimen. Several of the less powerful second-line drugs, which are required to treat MDR-TB, are also more toxic, with side effects such as nausea, abdominal pain, and even psychosis. The Partners in Health team had treated patients in Peru who were sick with strains that were resistant to ten and even twelve drugs. Most such patients require adjuvant surgery for any hope of a cure.

There are several ways that drug resistance to TB, and drug resistance in general, can be prevented:

1. Rapid diagnosis & treatment of TB: One of the greatest risk factors for drug resistant TB is problems in treatment and diagnosis, especially in developing countries. If TB is identified and treated soon, drug resistance can be avoided.

2. Completion of treatment: Previous treatment of TB is an indicator of MDR TB. If the patient does not complete his/her antibiotic treatment, or if the physician does not prescribe the proper antibiotic regimen, resistance can develop. Also, drugs that are of poor quality or less in quantity, especially in developing countries, contribute to MDR TB.

3. Patients with HIV/AIDS should be identified and diagnosed as soon as possible. They lack the immunity to fight the TB infection and are at great risk of developing drug resistance.

4. Identify contacts who could have contracted TB: i.e. family members, people in close contact, etc.

5. Research: Much research and funding is needed in the diagnosis, prevention and treatment of TB and MDR TB.

"Opponents of a universal tuberculosis treatment, reasoning from misguided notions of cost-effectiveness, fail to acknowledge that MDRTB is not a disease of poor people in distant places. The disease is infectious and airborne. Treating only one group of patients looks inexpensive in the short run, but will prove disastrous for all in the long run."- Paul Farmer

There are several causes of acute pericarditis. In developed nations, the cause of most (80–90%) cases of acute pericarditis is unknown but a viral cause is suspected in the majority of such cases. The other 10–20% of acute pericarditis cases have various causes including connective tissue diseases (e.g., systemic lupus erythematosus), cancer, or involve an inflammatory reaction of the pericardium following trauma to the heart such as after a heart attack such as Dressler's syndrome. Familial mediterranean fever and TNF receptor associated periodic syndrome are rare inherited autoimmune diseases capable of causing recurring episodes of acute pericarditis.

The risk factors for SCD are similar to those of coronary artery disease and include age, cigarette smoking, high blood pressure, high cholesterol, lack of physical exercise, obesity, diabetes, and family history. A prior episode of sudden cardiac arrest also increases the risk of future episodes.

Current cigarette smokers with coronary artery disease were found to have a two to threefold increase in the risk of sudden death between ages 30 and 59. Furthermore, it was found that former smokers risk was closer to that of those who had never smoked.

Vietnamese tuberculosis refers to certain forms of chronic melioidosis that look clinically very similar to tuberculosis. It is derived from the clinical appearance of the disease in American soldiers returning from the Vietnam War.