Cases of<unk> berculosis have been reported in every country surveyed.<unk>  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<unk> berculosis is an airborne pathogen, persons with active, pulmonary tuberculosis caused by a<unk> -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<unk> . Levels are much higher in those previously treated for tuberculosis - about 20%. WHO estimates that there were about 0.5 million new<unk>  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<unk> . 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<unk>  were clustered. Likewise, the appearance of high rates of<unk>  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<unk>  cases could be traced back to prisons and homeless shelters. When patients have<unk> , they require longer periods of treatment—about two years of<unk>  regimen. Several of the less powerful second-line drugs, which are required to treat<unk> , 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. Somalia<unk>  is widespread in Somalia, where 8.7% of newly discovered TB cases are resistant to Rifampicin and Isoniazid, in patients which were treated previously the share was 47%. Refugees from Somalia brought an until then unknown variant of<unk> berculosis with them to Europe. A few number of cases in four different countries were considered by the European Centre for Disease Prevention and Control to pose no risk to the native population. Russian prisons One of the so-called "hot-spots" of drug-resistant tuberculosis is within the Russian prison system. Infectious disease researchers Nachega & Chaisson report that 10% of the one million prisoners within the system have active TB. One of their studies found that 75% of newly diagnosed inmates with TB are resistant to at least one drug; 40% of new cases are<unk> -resistant. In 1997, TB accounted for almost half of all Russian prison deaths, and as Bobrik et al. point out in their public health study, the 90% reduction in TB incidence contributed to a consequential fall in the prisoner death rate in the years following 1997. Baussano et al. articulate that concerning statistics like these are especially worrisome because spikes in TB incidence in prisons are linked to corresponding outbreaks in surrounding communities. Additionally, rising rates of incarceration, especially in Central Asian and Eastern European countries like Russia, have been correlated with higher TB rates in civilian populations. Even as the DOTS program is expanded throughout Russian prisons, researchers such as Shin et al. have noted that wide-scale interventions have not had their desired effect, especially with regard to the spread of drug-resistant strains of TB. Contributing factors There are several elements of the Russian prison system that enable the spread of<unk>  and heighten its severity. Overcrowding in prisons is especially conducive to the spread of tuberculosis; an inmate in a prison hospital has (on average) 3 meters of personal space, and an inmate in a correctional colony has 2 meters. Specialized hospitals and treatment facilities within the prison system, known as TB colonies, are intended to isolate infected prisoners to prevent transmission; however, as Ruddy et al. demonstrate, there are not enough of these colonies to sufficiently protect staff and other inmates. Additionally, many cells lack adequate ventilation, which increases likelihood of transmission. Bobrik et al. have also noted food shortages within prisons, which deprive inmates of the nutrition necessary for healthy functioning. Comorbidity of HIV within prison populations has also been shown to worsen health outcomes. Nachega & Chaisson articulate that while HIV-infected prisoners are not more susceptible<unk>  infection, they are more likely to progress to serious clinical illness if infected. According to Stern, HIV infection is 75 times more prevalent in Russian prison populations than in the civilian population. Therefore, prison inmates are both more likely to become infected with<unk>  initially and to experience severe symptoms because of previous exposure to HIV. Shin et al. emphasize another factor in<unk>  prevalence in Russian prisons: alcohol and substance use. Ruddy et al. showed that risk for<unk>  is three times higher among recreational drug users than non-users. Shin et al.'s study demonstrated that alcohol usage was linked to poorer outcomes in<unk>  treatment; they also noted that a majority of subjects within their study (many of whom regularly used alcohol) were nevertheless cured by their aggressive treatment regimen. Non-compliance with treatment plans is often cited as a contributor to<unk>  transmission and mortality. Indeed, of the 80 newly-released TB-infected inmates in Fry et al.'s study, 73.8% did not report visiting a community dispensary for further treatment. Ruddy et al. cite release from facilities as one of the main causes of interruption in prisoner's TB treatment, in addition to non-compliance within the prison and upon reintegration into civilian life. Fry et al.'s study also listed side effects of TB treatment medications (especially in HIV positive individuals), financial worries, housing insecurities, family problems, and fear of arrest as factors that prevented some prisoners from properly adhering to TB treatment. They also note that some researchers have argued that the short-term gains TB-positive prisoners receive, such as better food or work exclusion, may dis-incentivize becoming cured. In their World Health Organization article, Gelmanova et al. posit that non-adherence to TB treatment indirectly contributes to bacterial resistance. Although ineffective or inconsistent treatment does not "create" resistant strains, mutations within the high bacterial load in non-adherent prisoners can cause resistance. Nachega & Chaisson argue that inadequate TB control programs are the strongest driver of<unk>  incidence. They note that prevalence of<unk>  is 2.5 times higher in areas of poorly controlled TB. Russian-based therapy (i.e., not DOTS) has been criticized by Kimerling et al. as "inadequate" in properly controlling TB incidence and transmission. Bobrik et al. note that treatment for<unk>  is equally inconsistent; the second-line drugs used to treat the prisoners lack specific treatment guidelines, infrastructure, training, or follow-up protocols for prisoners reentering civilian life. Policy impacts As Ruddy et al. note in their scholarly article, Russia's recent penal reforms will greatly reduce the number of inmates inside prison facilities and thus increase the number of ex-convicts integrated into civilian populations. Because the incidence of<unk>  is strongly predicted by past imprisonment, the health of Russian society will be greatly impacted by this change. Formerly incarcerated Russians will re-enter civilian life and remain within that sphere; as they live as civilians, they will infect others with the contagions they were exposed to in prison. Researcher Vivian Stern argues that the risk of transmission from prison populations to the general public calls for an integration of prison healthcare and national health services to better control both TB and<unk> . While second-line drugs necessary for treating<unk>  are arguably more expensive than a typical regimen of DOTS therapy, infectious disease specialist Paul Farmer posits that the outcome of leaving infected prisoners untreated could cause a massive outbreak of<unk>  in civilian populations, thereby inflicting a heavy toll on society. Additionally, as<unk>  spreads, the threat of the emergence of totally-drug-resistant TB becomes increasingly apparent.
Multidrug-resistant tuberculosis
Extensively drug-resistant tuberculosis
Totally drug-resistant tuberculosis
Primary inoculation tuberculosis
Extrapulmonary tuberculosis
Tuberculosis
Miliary tuberculosis
Chronic pulmonary aspergillosis