Is tuberculosis a curable disease

Dot Nepal presents an informative article on “Tuberculosis”. Tuberculosis is by far the most frequently encountered mycobacterial disease in the world. Among the infectious diseases, it is the commonest cause of death in adults and after acute respiratory and diarrhoeal disease, in children. The disease is preventable and treatable but it has been grossly neglected and no country is immune to it. World Health Organization (WHO) and International Union Against TB and lung Disease (IUATLD) declared the diagnosis of TB infection is vital both clinically and epidemiologically as well as early diagnosis, effective treatment and successful cessation of transmission are major strategies in the control of TB. The world-wide threat to human health is now so serious that, in 1993, the world health organization (WHO) took the unprecedented step of declaring tuberculosis a global emergency. This has led to a increase awareness of the disease by physicians and the general public.

What is Tuberculosis

Tuberculosis is one of the world’s most widespread and deadly illnesses. Mycobacterium tuberculosis, the organism that cause tuberculosis infection and disease infects an estimated 20-43% of the world’s population. Each year three million people worldwide die of the disease. Tuberculosis occurs disproportionately among disadvantaged population such as the malnourished homeless and those living in overcrowded and substandard housing. There is an increasing occurrence of tuberculosis among HIV-positive individuals (Tierney et al 2006). Many of the symptoms of tuberculosis are not caused by the tubercle bacilli themselves but this is a result of immunological hypersensitivity reaction of the host. This disease has the potential to infect virtually every organ, most importantly the lungs due to dissemination through lympho-hematogenous route (Haas,2000).

Occasionally the primary infection progress locally to a more widespread lesion. Haematogenous spread can also occur. giving millary tuberculosis. Tuberculosis in adults is therefore usually the result of reactivation of old disease, occasionally a primary infection or more rarely, reinfection (Kumar and Clark, 2001). The capacity of mycobacterium to produce disease is therefore attributed to their ability to multiply within phagocytic cells and to withstand intracellular enzymatic action.

In addition to the tubercle and leprosy bacilli, there are many other species of mycobacterium that live freely in the environment. These are normally harmless saprophytes but some species are causes of human and animal diseases (Collins, et al.,1997).

From the purely clinical point of view, mycobacteria are divisible into the groups (Grange and Collins,1983).

1) The obligate pathogens –the M. tuberculosis complex and M. laprae;
2) Species that normally live freely in the environment but also cause opportunist infections in humans; and
3) Species that never, or with extreme rarity cause disease.

Tuberculosis of the lung is called the pulmonary tuberculosis (PTB) and it is the most frequently infected organ and is the most common form of tuberculosis. PTB is also called as ‘open case’ of tuberculosis. The term ‘open tuberculosis’ is applied to those cases in which bacilli are detected in the sputum. For the diagnosis of pulmonary tuberculosis, the essential conditions must possess the followings signs and requirements. These essentials of diagnosis are:

a) Fatigue, weight loss fever, night sweats and cough.
b) Pulmonary infiltrates on chest radiography, most often apical
c) Positive tuberculin skin test reaction (most cases)
d) Acid fast bacilli on smear of sputum or sputum culture positive for M tuberculosis (Tierney et al., 2006).

How to Treat Tuberculosis

Most government health services now recgonize that TB control must go beyond DOTS, but the broader stop TB strategy is not yet fully operational in most countries. More than 90 million TB patients were reported to WHO between 1980 and 2005; 26.5 million patients were notified by DOTS programmes between 1995 and 2005, and 10.8 million new smear-positive cases were registered for treatment by DOTS programmes between 1994 and 2004.

DOTS, which underpins the stop TB strategy was being applied in 187 countries in 2005; 89% of the world’s population lived in areas where DOTS had been implemented by public health services. A Total of 199 countries/ areas reported 5 million episodes of TB in 2005 (new patients and relapses); 2.3 million new pulmonary smear-positive patients were reported by DOTS programmes in 2005, and 2.1 million were registered for treatment in 2004. (WHO Report, 2007).

DOTS was introduced for the first time in Nepal in April 1996 covering 1.7% of the population only. By July 2001, it has been expanded to all the districts of Nepal. Now all diagnosed TB patients are treated with DOTS. The National Tuberculosis Programme policy is to treat new smear-positive tuberculosis and other severe forms in new cases with Cat-I regimen (2HRZE/6HE) and retreatment cases with Cat-II regimen (2SHRZE/ 1HRZE/ 5HRE) at DOTS centres in public and private sectors throughout the country. New smear negative cases have been treated with Cat-III regimen (2HRZ/6HE).

The programme is currently considering switch from the current 8-month regimen to a 6-month regimen for new smear positive patients. Advantages of switching to a six-month regimen include a shorter total duration, higher efficiency if the initial intensive phase is not prolonged for patients remaining sputum smear positive at two months of treatment, and that this regimen is preferred by many private practitioners.

Nationally 33,450 TB patients were registered for treatment by NTP in 2006/07 and 89% successfully completed their treatment. The global target of 85% treatment success rate was achieved and improved on since introduction of DOTS in Nepal in 1996.