Unraveling The Complexity Of Tuberculosis Epidemiology

Transmission and Risk Factors

Discuss about the Tuberculosis for Epidemiology and Control.

A communicable disease is a disease that can be spread from person to person by different ways, which consists of contact with the body fluids or blood, transmission through breathing in any kind of airborne viruses, or through insect bites. Reporting of different types of cases involving the history of communicable diseases is very important and necessary to evaluate and plan various types of programs and steps for prevention and control of the disease, to assure proper medical therapy is achieved, and for detecting the common-source and cause of these outbreaks (11). Communicable diseases are one of the reasons for high mortality rate worldwide, and tuberculosis is considered as the world’s leading causes of infectious deaths, secondary to HIV (12). Despite that there are major achievements in the control of tuberculosis in the Northern Territory in the past few years, still, tuberculosis remains a concerning and significant problem in the Northern Territory, Darwin.

Tuberculosis (TB) is considered as the major threat to the public health, which competes with the most severe disease and cause of death called human immunodeficiency virus (HIV) due to the spread of infectious diseases overall the world. Though, a decline in the trend of incidence of tuberculosis, its prevalence, as well as, mortality is being observed for more than past ten years, the elimination of tuberculosis totally is still not reached and requires a massive investment of resources for its elimination (12). Tuberculosis is airborne and contagious disease, and the risk of having an infection from Mycobacterium tuberculosis is essentially characterized by various exogenous factors. It is mostly transmitted through the spread of droplet nuclei via a cough, sneezing, or speaking from the person that is infected with pulmonary tuberculosis to others. Other modes of transmission are not common and have no significance epidemiologically (16). The probability of getting contact with the individual who is infected, duration and intimacy with that person, extent of infectiousness, and shared environment are some of the important determinants of the transmission of tuberculosis. Moreover, tuberculosis is considered as a disease of poverty, which thrives mostly where economic and social determinants of the bad health prevail, as well as, which impacts mostly the young individuals in the productive years of their lives residing in the developing world (10).

Tuberculosis is a nationally notifiable communicable disease in Australia and previous reports and data on tuberculosis in Australia showed that the tuberculosis is still a major and concerning health problem, with main implications for the control of tuberculosis locally. However, the incidence of tuberculosis has remained stable in Australia since the year of 1986, around 1,135 total cases of tuberculosis were reported to be prevalent in Australia in the year 2007. Moreover, in the year 2007, around 1,086 new cases were notified of tuberculosis with around 48 cases of relapses. The largest increase over the period of 10 years related to the number of cases and incidents of tuberculosis were found to observed in the Northern Territory with about 39% increase, followed by 36% increase in Victoria, and about 24 % increase in Queensland. On the other hand, the largest decrease over the same period in the incident of tuberculosis was observed in the Australian Capital Territory with about 70% decrease. However, the potential source of bias that could have affected these rates slightly could be the small variation in the total number of cases of tuberculosis over period proportionate to the comparatively small residential population that is estimated.

Tuberculosis in Australia

Moreover, the rate of incidence of tuberculosis among the non-Indigenous population was 0.9 cases per 10,000 population with 6.6 cases per 10,000 population in case of Indigenous people. However, the potential source of bias in this could be an incomplete or invalid country of birth of the individuals and their Indigenous status (2). Moreover, in the year 2010, around 1,353 cases of tuberculosis were notified showing an increase of 3% in the number of cases in 2009.  The highest rate of tuberculosis’s incidence was observed in Northern Territory with about 12 cases per 10,000 population with least in Australian Capital Territory (1). Moreover, in 2013, about 42 cases were reported in the Northern Territory, which indicated an increase of 50% of the total number of tuberculosis cases estimated in the year 2012 (6). Further, it has been estimated that every year around 20 to 30 new cases are notified of active tuberculosis in the northern territory. While around 60% of the cases are seen to be prevalent in Aboriginal persons, about 30% of the cases in migrants, and around 10%  is the remainders of the area (7). The ecological factors that are responsible for more incidence of tuberculosis, especially in the Indigenous people in comparison to the now- indigenous people are poverty, malnutrition, and overcrowding. Moreover, other risk factors for the development of tuberculosis are alcohol use, tobacco use, kidney disease, the incidence of tuberculosis is high in an Indigenous community as the Aboriginal and Torres Strait Islander individuals have these risk factors in common (14).

According to the World Health Organization (WHO), around 8.6 million of total cases of tuberculosis were estimated to occurred worldwide in the year 2012, with about 2.9 million of it were those involving women. The research has shown that the majority of the cases of tuberculosis were estimated to occurred in Africa with about 27 % and 58 % of the cases in Asia, with the high number of cases in India and China (3). The global rate of incidence of tuberculosis was declining slowly from the year of 1997 to 2001, but an increase in the incidence of tuberculosis was observed in the year 2001 due to increasing in the number of cases of tuberculosis  among the patients who were infected with HIV in Africa.  Despite effective chemotherapy and medical treatments are available for tuberculosis, about 1.3 million people were killed in 2012 by tuberculosis (5). According to the WHO report, in the year 2014, a marked increase was observed in the global tuberculosis notifications since the year 2007. Moreover, the annual total of the prevalence of the new cases of tuberculosis that had been around 5.7 million cases until the year 2013 was found to increase to more than about 6 million cases in the year 2014, i.e., with an increase of about 6% of the total cases worldwide (4). It has been estimated that more than one-third of the 6 billion people of the world are infected with tuberculosis and about more than  9 million new cases are reported annually of active tuberculosis with about 2-3 million deaths worldwide, thus, making it one of the the leading reason of mortality from one infectious organism (7). The ecological factors that are responsible for the increasing incidence of tuberculosis globally include increase in poverty rates, homelessness, malnutrition, and overcrowding mostly among urban populations. Moreover, the increased use of tobacco, alcohol, substance abuse, and unprotected intercourse can also lead to the incidence of tuberculosis. As tuberculosis is still the leading cause of mortality after HIV worldwide, it is a significant issue and requires better and effective care and management of tuberculosis and people infected with this disease (13).

Global Incidence of Tuberculosis

The Centre for Disease Control (CDC) is one of the public health unit, which is responsible and accountable for the management and control of tuberculosis, leprosy, as well as, nontuberculous mycobacteria occurring in the Northern Territory. The Centre for Disease Control in Darwin works in collaboration and coordinates its service, with other tuberculosis/leprosy units that are located in Nhulunbuy, Katherine, Alice Springs, and Tennant Creek. These units have access and approach to a team consisting of various health professionals consisting of medical officers, Aboriginal Health Workers, nurses, as well as, administration staff for running these services under the supervision direction of the Centre for Disease Control’s Director and head of the tuberculosis/leprosy/ nontuberculous mycobacteria sections. Tuberculosis, as well as, leprosy are the diseases that are of significant importance concerning public health in the Northern Territory. The main focus of the Centre for Disease Control is on the screening for tuberculosis in the Indigenous population residing locally, the ones that born overseas, involving students of international University and school, but illegal foreign fishermen and newly arrived refugees are also the focus of the Centre for Disease Control. The Centre for Disease Control identifies the cases of tuberculosis with the help of comprehensive free screenings of the individuals those are at increased risk of having tuberculosis and passively by referring those individuals who are positive for the symptoms to the health services. Further, these patients are diagnosed and managed according to their current protocol. The management, as well as, coordination of the various policies for the control of tuberculosis in the Northern Territory includes various strategic planning, its implementation, as well as, surveillance keeping the long term aim to eliminate tuberculosis in the Northern Territory. The enhanced surveillance, notification, and  statistical analysis based on the tuberculosis data is conducted for the Northen Territory by the Centre for Disease Control. Moreover, the Centre for Disease Control also aims at providing various clinical services for the individuals who are infected with active TB or have latent tuberculosis infection involving advice regarding inpatient management, contact tracing, and community screening. Further, it produces the comprehensive guidelines and policies for the control and management of Tuberculosis in the Northern Territory. Education of various health professionals, the government and public agency staff about the tuberculosis, comprising education of the provision of the standards, advice, training, and guidelines. This further involves contribution to the Communicable Diseases Bulletin quarterly. Representation on Northern Territory and national committees regarding tuberculosis, leprosy, health screening of refugees and illegal foreign fishermen is also carried out. Further, the Centre of Disease Control liaises with the Melaleuca Refugee Centre for ensuring the provision of initial assessments of health for newly arrived refugees. It also involves in the research that is related to tuberculosis and leprosy having a direct aim of managing and improving the regional control of tuberculosis (8).  The Centre for Disease Control is successful in controlling and managing tuberculosis as the number of cases of tuberculosis are observed to be declining especially in the Indigenous Community of the Northern Territory and Australia is considered to be the least affected country by tuberculosis globally. The Centre for Disease Control is still working and making efforts for eliminating tuberculosis from the Northern Territory and is achieving through their guidelines and policies (9).

Public Health Management and Control of Tuberculosis

Conclusion

After human immunodeficiency virus or AIDS, tuberculosis is the second most commonly occurring cause of deaths worldwide due to the presence of the infectious organism. The current trends in the study of the prevalence and incidence of tuberculosis suggest that tuberculosis will still continue to be the leading reason behind the global disease burden even in the year 2020. The distribution of tuberculosis cases worldwide is skewed mainly towards the low-income, as well as, emerging economies. Hence, the highest rates of prevalence of tuberculosis are observed in Asia, where India, Bangladesh, China, Pakistan, and Indonesia collectively contributes about more than 50% of the total global burden (10). Due to the increasing global burden caused by the incidence of tuberculosis, it is very important to take necessary methods for controlling and management of tuberculosis. Early diagnosis, as well as, treatment of tuberculosis, periodic screening for evaluating the cases of tuberculosis, provision of BCG vaccination, and proper management of the surrounding environment with proper ventilation, good hygiene, and natural light are few steps which can help in controlling tuberculosis (15).

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