Introduction
TB, a contagious chronic disease that primarily affects the lungs is caused by the inhalation of Mycobacterium bacilli (Hanif & Garcia-Contreras, 2012). Today, TB remains a serious public health concern in many parts of the world (Hanif & Garcia-Contreras, 2012).
Surveys by WHO indicate TB infections and fatalities were especially high in the 90s and early this decade but since 2006, massive awareness and treatment campaigns have seen a gradual decline in incidence rate, prevalence and fatalities (Hanif & Garcia-Contreras, 2012).
Infection is triggered by inhalation of air droplets containing Mycobacterium tuberculosis bacilli (MTB) from an infected person. Although a strong immune system can contain the pathogen, in an immunosuppressed individual, the MTB is capable of multiplying and rupturing the host’s macrophages, resulting in the destruction of the body’s primary line of defense against it.
Upon rupture of infected macrophages, monocytes leave the systemic circulation under the influence of chemotactic factors and initiate granuloma formation (Hanif & Garcia-Contreras, 2012). It is believed that before the body mounts an active defense against MTB, the bacilli would have already escaped from the lungs into the bloodstream and spread to other parts of the body (Hanif & Garcia-Contreras, 2012).
Tuberculosis Skin Test that utilizes a Purified Protein Derivative (PPD) has long been used to diagnose TB. However, the main drawback of PPD is that it is unable to distinguish the real pathogenic bacilli for TB from that of BCG vaccination and environmental non-tuberculosis mycobacterium (Hanif & Garcia-Contreras, 2012).
For a long time, BCG vaccine has been used to offer protection against TB. The vaccination involves injecting attenuated MTB strains into a child’s body to stimulate an immunity that confers resistance against future infections.
Despite being taken as the standard protection against TB in many parts of the world, BCG clinical studies have revealed variations in its efficacy. The variations have been attributed to strains mutations, enviromental factors(e.g sunlight and cold exposure), genetics, nutritional as well as prior exposures to the microbacterium (qtd. in Hanif & Garcia-Contreras, 2012).
Treatment of TB is a long and demanding process(qtd. in Hanif & Garcia-Contreras, 2012). The duration of drug therapy may range from a minimum of 6 months to a high a 24 months depending on the combination administered. Treatment is further complicated by unwanted toxic effects and mutations of M. tuberculosis which may call for slowing or dropping of the treatment altogether.
This papers is an attempt to examine newer therapies currently being tested or proposed to augment traditional drug therapies for TB. These therapies are gaining attention from different health quarters given the shortcomigs of BCG as the primary protection method and increasing health challenges brought about by changing aetiology of the disease.
The first section discusses the use of pharmaceutical aerosols in treatment and prevention of TB. The second part deals with nutritional intervention specifically, Vitamin D while the last section examines the same in light of systemic physical therapy. A conclusion is then made on how the above three inform clinical and pharmaceutical practise partaining to TB.
Pharmaceutical Aerosols
Pharmaceutical aerosols represent attempts to produce more effective novel drugs for prevention and treatment of TB. Although studies in test animals have been promising, no pharmaceautical aerosol for TB has been produced so far (Hanif & Garcia-Contreras, 2012).
Aerosol formulations of drugs and vaccines for TB treatment have produced desired effects in animals they have been tested. Notably, higher drug concentration at target site, reduced systemic side effects, as well as carrier properties that could be applied in vaccine development have been reported.
A number of tubercular formulations tested have produced positive results. Capreomycin powder aerosol attains high deposition in lungs giving hope that similar concentrations are attainable in human subjects. Dry powder PA-824 aerosol has shown even more promising results in guinea pigs.
Low or high dose of this compound in guinea pigs was associated with reduced manifestation of TB in lungs and spleen, lower number of the bacteria as well as less tissue damage (qtd. in Hanif & Garcia-Contreras, 2012). Similar results have also been achieved with vaccines aerosols. BCG particles administered by pulmonary route were found to produce lower bacterial burden compared to unimmunized controls.
Mircroparticles have also been found effective in acting as transporters of vaccines to target cells in order to iniate cell mediated immunity. Similarly, r-Ag 85B-PLGA microsphere has been found effective in delivering antigens to macrophages for processing and presentation to CD4 cells. This has led scientist to cite this findings as potential vaccine strategy for preventing TB.
Systemic physical training and TB prevention
It has been observed in the medical field that long, narrow, flat chested individuals are more susceptible to TB and suffer TB related fatalities the most (Ingals). This has led some to reason that physical training to build respiratory muscles and expand thoracic walls could be important in the prevention and cure of TB.
According to this line of reasoning, physical training promotes deep breathing. The deep breathing is said to aid in the emptying of pathogenic agents from lungs. The kind of breathing advocated in this therapy involves a long, deep breath with the abdominal walls drawn in, shoulders pushed backwards and accompanied with elevation of ribs and sternum (Ingals n.p).
This technique of breathing is said to completely inflate and deflate most, if not all of the air cells in the lungs thus faciliting the removal of pathogenic agents that may cause TB. Cases of increased chest circumference have been cited in studies of college students involved in weekly physical activities over period ranging from 6 months to 24 years.
However, it has been acknowledged that the increase cannot be conclusively attributed to the physical activity as other factors such as natural growth could be the cause (Ingals n.p). Further controversy regarding this theory is the observation in many studies that athletes, despite high physical activity in their early life, tend to die young with pulmorary tuberculosis accounting for a good number of such deaths (Ingals).
By and large, systemic physical activity training as an intervention for treating and preventing TB lacks sufficient empirical evidence to support it and more research is needed for it to be taken seriously.
Vitamin D in prevention and treatment of TB
Treatment of TB using cod liver oil, an extract highly rich in vitamin D dates back to the 19th century. In addition, many studies have also proved the efficacy of the active form of Vitamin D in destroying and preventing the growth of mycobacterium TB in-vitro (Dini & Bianchi, 2012).
Diani and Bianchi (2012) list numerous studies that show low vitamin D to be a risk factor in development of active TB. The corroborating studies were conducted in Spain ,South Africa, Tanzania, Australia, Pakistan, Viatman, UK, Indonesia, Kenya, Thailand, Hong Kong, and India.
Notable differences in association between vitamin D and TB in countries near or on geographic equator and those far away from equator have been documented suggesting sunlight influences vitamin D levels (Dini & Bianchi, 2012) It has also been reported that TB patients tend to have lower than recommended levels of Vitamin D compared to healthy individuals (Dini & Bianchi, 2012).
Vitamin D is reported to play a central role in activation of Cathelicidin, a compound found to have a destructive effect not only on Mycobacterium tuberculosis but also on a host of other viruses. Researchers are particularly interested in understanding the working mechanism of cathelicidin at cellular level in initiating cell mediated immunity during Mycobacaterium tuberculosis infection.
It is believed deciphering the working mechanism of this compound could greatly contribute to development of multi-faceted therapies that could be effective even for the obstinate multi-drug resistant TB (MDR-TB) (Dini & Bianchi, 2012).
As many studies have shown, antibacterial chemotherapy coupled with vitamin D supplements could be more effective in treatment of TB than either of the interventions alone (Dini & Bianchi, 2012). This mode of treatment of is particularly attractive due to its low cost and easy administration.
Conclusion
TB is a serious public health concern in many parts of the world. The most recognised traditional intervention of choice is BCG vaccination during childhood.Given the evolving nature of the disease’s causative agent, newer approaches have become necessary. Aerosols formulations to treat TB yield promising results in test animals although the benefits in human subject are far from being concluded.
Studies have proved the debilitating effects of Vitamin D on development of active TB and efforts are underway to make it part of anti-bacterial chemotherapy. Systemic physical training to enlarge the chest has also been suggested. However, this approach lacks sufficient empirical evidence to support it.
References
Dini, C., & Bianchi, A. (2012). Potential role of Vitamine D for prevention and treatment of tuberculosis and infectious diseases. Ann Ist Super Sanita, 48(3), 319-327.doi: 10.4415/ANN_12_03_13.
Hanif, S. N., & Garcia-Contreras, L. (2012). Pharmaceautical aerosols for the treatment and prevention of Tuberculosis. Front Cell Infect Microbiol, 2, 118.doi:10.3389/fcimb.2012.00118.
Ingals, F. (n.d.). Value of systemic physical training in the prevention an cure of pulmorary tuberculosis. Chicago.