CHAPTER 2 LITERATURE REVIEWS

Transcription

1 CHAPTER 2 LITERATURE REVIEWS This literature review includes three parts. 1. General information regarding pulmonary tuberculosis 1.1 Natural history of pulmonary tuberculosis 1.2 Risk groups for developing tuberculosis 1.3 Diagnosis test for tuberculosis 1.4 Treatment and prevention of tuberculosis 2. Tuberculosis preventive behaviors 3. Factors related to TB preventive behavior 3.1 Socio-demographic factors which are associated with tuberculosis preventive behaviors 3.2 Knowledge factors 3.3 Perception factors General information regarding pulmonary tuberculosis 1. Natural history of pulmonary tuberculosis Tuberculosis (TB) is a disease caused by germs that are spread from person to person through the air. It usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine. A person with TB can die if they do not get treatment (CDC, 2012). Tuberculosis is a chronic infectious and communicable granulomatous disease caused by mycobacterium tuberculosis (Reza, 2009).The tubercle bacilli establish infection in the lungs after they are carried in droplets small enough (5 to10 microns) to reach the alveolar spaces. If the defense system of the host fails to eliminate the infection, the bacilli proliferate inside alveolar macrophages and eventually kill the cells. The infected macrophages produce cytokines and chemokines that attract other phagocytic cells, including monocytes, other alveolar macrophages and neutrophils, which eventually form a Nodular granulomatous structure called the tubercle. If the bacterial replication is not controlled, the tubercle enlarges and the bacilli enter local draining lymph nodes. This leads to lymphadenopathy, a characteristic

2 13 clinical manifestation of primary tuberculosis (Wani, 2013). 1.1 Source of TB infection There are two sources of TB infection human and bovine (connected with domestic and wild mammals). The most common source of infection is the human cases whose sputum is positive for tubercle bacilli and who has ether received no treatment or not been treated fully (Park, 2003). Amongst the members of the mycobacterium tuberculosis complex (MTBC), mycobacterium tuberculosis is mainly a human pathogen, whereas mycobacterium bovis has a broad host range and is the principal agent responsible for tuberculosis (TB) in domestic and wild mammals. Mycobacterium bovis also infects humans, causing zoonotic TB through ingestion, inhalation and, less frequently, by contact with mucous membranes and broken skin. Zoonotic TB is indistinguishable clinically or pathologically from TB caused by M. tuberculosis (Rua- Domenech, 2006). In addition, the causative agent of bovine tuberculosis, mycobacterium bovies, is also responsible for some cases of tuberculosis in human beings. Infection of human beings with mycobacterium bovis almost always occurs by inhalation of aerosols or consumption of milk containing the bacillus. Although milk was the usual source of infection of town dwellers, it was considered likely that farm workers were often infected by mycobacterium bovis by inhalation and acid-fast bacilli were seen in dried bovine sputum on the walls and windows of cowsheds (Grange, 2001). 1.2 Mode of transmission Tuberculosis is transmitted mainly by droplet infection and droplet nuclei generated by sputum positive patients with pulmonary tuberculosis. The frequency and vigor of cough and the ventilation of the environment influence transmission of infection (Park, 2003). Tuberculosis is spread through the air from one person to another. The bacteria are put into the air when a person with tuberculosis disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected. TB disease in the lungs or throat can be infectious. This means that the bacteria can be spread to other people. Untreated pulmonary TB can spread the infection but treatment after two weeks TB cannot spread to the others. People with TB disease are most likely to spread it to people they spend time with every day. This includes family members, friends, and coworkers or schoolmates (CDC, 2012).

3 14 2. Risk groups for developing tuberculosis Several factors are related to develop TB including source case, the organism, the environment, and persons who are exposed to the source cases. Generally, mycobacterium tuberculosis is not highly contagious. However, people who are in close contact with an individual who has an infectious form of tuberculosis are at increased risk of acquiring the infection (Morrison, Pai, & Hopewell, 2008). Therefore, the risk groups for developing pulmonary TB include the following; 2.1 Patients attendants Patients attendants of infectious TB patients are a high risk group because of prolonged close exposure to an infectious person. Tuberculosis infections usually spread between family members who live in the same house. Patients attendants are at more risk than other members of the family because they spend more time and close contact with TB patients to provide necessary care. They take care of some part of activities when the patients are unable to meet their basic need of daily living during the sick periods. Sabir et al. (2012) found that 43% of TB patients attendants spent 1-6 hours period with the patient for necessary care. A study by Wang and Lin (2000) found that the risk of TB infection among household contact of index TB patients in Taipei is high. Households of persons with active TB serve as breeding places for TB, and household contact investigation has proved very efficient in finding TB cases. The smear-positivity of the index patient supports its role as the potential source of infection for other household members and there is a higher frequency of TB in households of index TB patients (Claessens et al, 2002; Kopec et al., 2012). The incidence of active TB among adult household contacts of sputum smear-positive pulmonary tuberculosis cases was high especially in the year age group (Kilicaslan et al., 2009). Alavi and Farahmand, (2008) found that the higher prevalence of active tuberculosis among household contacts than in the contact outside the household (18.2% vs.1.6%). 2.2 HIV/ AIDS infected persons HIV infected people are more risk group of people for developing pulmonary tuberculosis. HIV infection significantly increases the risk of progression from latent to active TB disease. Low CD4 cells in HIV-infected persons indicates severely depressed immunity that makes them susceptible to fresh TB infection or reactivation of latent infection and rapid degradation of clinical condition. It has

4 15 already been established that TB attributed to a six-fold to seven-fold increase of viral load in HIV positive population (Giri, Deshpande, & Phalke, 2013). Patients with low immunity due to HIV are more likely to acquire tuberculosis in an area with high tuberculosis prevalence (Ngowi, Mfinanga, Bruun, & Morkve, 2008). Tuberculosis is one of the most common life-threatening infections among the persons living with HIV/ AIDS, but it does not inevitably follow that HIV is common in TB patients. Earlier surveys conducted in Bangladesh to evaluate the prevalence of HIV in TB patients have shown insignificant levels (Mahmood, 2010). 2.3 Diabetes mellitus (DM) persons People who have Diabetes mellitus (DM) and live with TB patients, they are more risk for developing TB disease. Body immunity is a key power to protect the body from infectious disease. Incidence of tuberculosis is greatest among those with conditions impairing immunity such as human immunodeficiency virus (HIV) infection and diabetes (Stevenson et al., 2007). Ponce-De- Leon et al. (2004) found the estimated rates of tuberculosis for the study area were greater for patients with diabetes than for nondiabetic individuals (209.5 vs per 100,000 person-years). Studies from different parts of the world have shown that 5 30% of patients with TB present with concomitant Dibetis Mallitus (Ruslami, Aarnoutse, Alisjabana, Vanderven, & Van Crevel, 2010). 3. Diagnosis test for tuberculosis According to National guidelines and operational manual for TB control in Bangladesh, the most cost effective tool for screening pulmonary tuberculosis (PTB) is microscopic examination of their sputum by the Ziehl Neelsen method. Over 65% of pulmonary TB patients are smear- positive and will be detected by this method. Sputum examination is the most reliable procedure for TB diagnosis. Moreover, some finding need to assess together that are-clinical history, possible adult contract, tuberculin skin test (TST), radiographs, Bacteriological test Erythrocyte sedimentation rate( ESR) and histopathological test for confirm diagnosis (Reza, 2009). Most tuberculosis diagnosis programs use direct smear examination of sputum but, if resources permit, a culture is desirable. Reliable susceptibility testing is a luxury few developing countries can afford, although it is especially desirable for purposes of re-treatment. Rapid methods of culture and susceptibility testing are

5 16 widely available in the wealthier nations. Molecular techniques have provided quick, sensitive, and specific tests for Mycobacterium tuberculosis such as polymerase chain reaction, DNA and RNA probes, and γ interferon tests but these are expensive and technically demanding (Campbell & Bah-Sow, 2006). Tuberculosis can affect any one but some people are more vulnerable to develop this infection 4. Treatment and prevention of tuberculosis Currently, the standard short-course chemotherapy for tuberculosis treatment comprises a 6-month regimen. There are four drugs for the intensive phase Isoniazid (INH), Rifampin (RIF), Pyrazinamide (PZA), Ethambutol (EMB), and two-drugs for continuation phase Isoniazid (INH) and Rifampin (RIF). The 4-month continuation phase is used for the majority of patient s only two drugs. Although these regimens are broadly applicable, there are modifications that should be made under specified circumstances. Alternative chemotherapy using more costly and toxic drugs, often for prolonged duration s generally 18 months is required for multidrug-resistant and extensively drug-resistant tuberculosis. Directly observed treatment, (DOT) as part of a holistic care program, it is a cost-effective strategy to ensure high treatment success and curtail development of drug resistance in tuberculosis (Yew, Lange, & Leung 2010). There are two types of prevention clinical and behavioral preventive measures. Clinical preventions are vaccination with Bacillus Calmette Guérin (BCG), and isoniazid preventive therapy is used to prevent TB infection. BCG vaccination significantly reduces the risk of tuberculosis by an average of 50%. Vaccination with BCG was significantly associated with a reduction in the incidence of pulmonary tuberculosis and extra pulmonary disease (Brewer, 2000). Preventive therapy with isoniazid reduces the risk of disease among recently infected children by 60 80%, and side-effects are rare. Preventive treatment among adults with latent tuberculosis infection also has a protective efficacy in the range 60-80%, depending on the duration of therapy. Effectiveness in routine practice may be limited by partial uptake and compliance (Borgdorff, Floyd, & Broekmans, 2002). Strongest adherence to continued isoniazid treatment in participants with a positive tuberculin skin test was associated with the largest decrease in tuberculosis incidence. (Samandari et al., 2011).

6 17 Another preventive measure is tuberculosis preventive behavior. Tuberculosis preventive behavior is the activity to perform by an individual and belief these activities which are able to promote healthy life and prevent the transmission of TB infection from one person to another person. These activities are taking healthy food, avoiding close contact of TB patients, seeking health care and attaining screening program, keeping house good ventilation and reading health news about TB. Tuberculosis preventive behavior is intent to prevent TB and actual behaviors taken to prevent this disease. Health education programs about tuberculosis information for the general population can play an important role to create awareness about TB preventive measure and influence the people to perform TB preventive activities. In conclusion, tuberculosis is an infectious communicable disease caused by mycobacterium tuberculosis. It can affect the any part of the body. However, the lungs are more commonly affected organ of TB. There are two source of TB infection a) human and b) bovine. Any infected TB case can be the main source of spread of the TB infection. It is transmitted by droplet infection and droplet nuclei generated by infected TB patients. Sputum microscopic examination, X-ray, and Tuberculin Skin Test (TST) is the common test for TB diagnosis. However, anyone can be infected by TB, but some risk factors play an important role to develop TB infection, such as immune depressive disease like Diabetes, HIV/ AIDS and people with low socioeconomic status, and especially the TB patients attendants and family members who have close contact with TB patients. TB patients attendants are more at risk than other members of the family because they spend more time with close contact. Tuberculosis is preventable and curable disease. Effective drugs and diagnostic tests are available. After six months of treatment, TB is completely cured. Isoniazide therapy, BCG vaccination and effective health education are the preventive measures of TB infection. Early case detection and treatment is important to reduce the risk of TB transmission. Effective drugs and treatment facilities are available for better treatment of TB patients but it is not enough to prevent TB infection. Tuberculosis preventive practice plays an important role to protect the people from this infection and it can reduce the transmission of infection from one person to another person.

7 18 Tuberculosis preventive behaviors Tuberculosis preventive behavior involves activities which individuals are willing to do to protect themselves from TB disease and promote health. Kasl and Cobb define preventive health behavior as "any activity undertaken by an individual who believes himself/ herself to be healthy for the purpose of preventing or detecting illness in an asymptomatic state" (Glanz et al., 2008). Tuberculosis is infectious communicable disease. It is spread through the air from one person to another. The bacteria are put into the air when a person with tuberculosis disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected. It is essential to control the transmission from one person to another. There are two types of preventive measures; clinical preventive measure and behavioral preventive measure. The clinical preventive measure focused on early case finding and treatment. The behavioral preventive measure focused on preventive activities. The behavioral preventive behavior focuses on the general health promoting activities. This mainly in respect to; living in good ventilated house, avoidance of overcrowding, avoidance of close contact with TB patients, good nutrition and better personal health habits with regard to spitting and coughing (Reza, 2009).Therefore, the recommended activities are; Living in a good ventilated house can be reducing the getting change of TB infection. Good ventilation spills out the bacteria from the house in order to reduce the TB bacterial overload in the house. People try to keep their house good ventilated when they can understand how it can prevent them from TB infection. Overcrowding is the factor for developing TB disease because it is air born disease. Avoidance of overcrowding area especially health care facilities where TB patients spend considerable time can be reducing the getting chance of TB. Good diet habit is the one of preventive measure of disease prevention and promotion of health. Malnutrition plays an important role to develop TB disease. Good nutrition increases the body immunity which is essential to protect the body from disease. Good dietary habit can be reducing the getting chance of TB by creating strong body immunity,

8 19 Avoiding close contact can reduce the chance of getting TB when taking care or working with TB patients. Sometimes people are exposed to TB case but may not be infected. People who have close contact with an infected person over a long period of time are at high risk for developing TB infection. Better personal health habit with regard to spitting and coughing can reduce the transmission of TB infection. When someone is coughing or sneezing during that time covering the mouth and nose can prevent TB infection. These behaviors not only prevent TB infection but also prevent other air borne infectious diseases. The WHO, (2009) policy on TB infection control in health-care facilities, congregate settings and households, set some policy to prevention of TB transmission in households these include: 1. Basic infection control activities It should be part of any community information, education and communication messages. The infection control messages need to promote the importance of early identification of cases, adherence to treatment and implementation of proper TB infection control measures (cough etiquette and respiratory hygiene) in the household, before and after diagnosis of TB. Behavior change campaigns for family members of smear-positive TB patients and health service providers should aim to minimize stigma and the exposure of non-infected patients to those who are infected (WHO, 2009). 2. Reduce households exposure Houses should be adequately ventilated, particularly rooms where people with infectious TB spend considerable time (natural ventilation may be sufficient to provide adequate ventilation). Anyone who coughs should be educated on cough etiquette and respiratory hygiene, and should follow such practices at all times. Smear positive TB patients should spend as much time as possible outdoors. Sleep alone in a separate, adequately ventilated room, if possible. Spend as little time as possible in congregate settings or in public transport (WHO, 2009). Factors related to TB preventive behaviors behaviors Socio-demographic factors which are associated with TB preventive

9 20 According to HBM and literature review, evidence demonstrated that sociodemographic factors including age, sex and education that can influence TB preventive behaviors. These factors are as follows; 1. Age Age is one of most important personal modifying factors that related to health behaviors. This factor may have an effect on individual perceived susceptibility and severity of disease. In additionally, perceived susceptibility and severity affect individuals to perceived health threat that stimulates the likelihood of taking recommended preventive health action. Therefore, age is indirectly related with preventive health behavior. Thwin and Chapman, (2009) confirmed that age is related to TB preventive behaviors and older age had good TB preventive behaviors. Therefore, age is an important personal factor in developing TB diseases. In Bangladesh, the Bangladesh National Tuberculosis Program has reported that among TB cases, three fourths belonged to age group years. One study from Bangladesh reported 70% of cases were within age group years and mean age was 36 years (Ahsan et al., 2004). 2. Sex Sex is another personal modifying factor that is related to health behavior. It can modify individuals perceived susceptibility and severity of disease. These perceptions affect individuals perceived health threat and it helps to make decisions about preventive behaviors. Different sex group have different perception about disease. Therefore, sex is indirectly related to preventive health behaviors. Thwin and Chapman, (2009) found that sex had significantly related with TB preventive behaviors (< 0.001). Their findings showed that females had more TB preventive practices than the males. The findings of Ahsan et al. (2004) strongly suggested that there was a significant sex difference in treatment seeking behavior in rural Bangladesh. Women in Bangladesh appear to have less access to public out-patient clinics than men, and if they present with respiratory symptoms they are less likely to undergo sputum smear examination (Begum et al., 2001).Males are more affected with TB than females and TB prevalence is higher among males than females (Khanum et al., 2012). Females have less access to the health care because they fear social isolation and worry about pressure to disclose TB because it is difficult to get married. So, sex plays an important role in performing TB preventive behavior.

10 21 3. Education Socio-demographic factors, particularly educational attainment are believed to have an effect on behavior by influencing the perception of susceptibility, severity, benefits and barriers (Glanz et al., 2008). Therefore, education plays an important role to practice TB preventive behaviors (Mohammadi, Tavaflan, Ghofranipoor, & Shokravi, 2012). It increases the knowledge level and knowledge creates awareness about disease. Thwin and Chapman, (2009) found that education had significantly related with TB preventive behaviors. Khandoker, Khan, Kramer, and Mori (2011) found that correct knowledge about TB disease was 3.5 times higher among women with 11 years of education than among women with no/ primary education. The likelihood of reporting correct knowledge was also significantly higher when spouses had higher secondary education as compared to no/ primary education. According to Hassnoot, Boeting, Kuney, and van Roosmalen (2010) education has a significant positive effect on knowledge. School children are more aware of TB and its etiology. Literates were more aware than illiterates about symptoms, treatment and preventive measures of tuberculosis (Yadav et al., 2006). Another study Sokhanya et al. (2008) confirmed that the education were significantly associated with TB preventive behavior. Knowledge factors Knowledge is a structural modifying factor of the HBM. It increases the individuals understanding and it can motivate decisions for change behaviors from negative to positive aspects by modifying individual perceived susceptibility, severity, benefits and barriers. Knowledge about tuberculosis plays an important role to prevent TB infection. Some studies revealed that people who have good knowledge, practice good TB preventive activities and seek medical treatment early (Sokhanya et al., 2008; Thwin & Chapman, 2009). Knowledge about transmission, treatment and preventive measure of tuberculosis determines going for examination when suspect sign of TB. 1. Knowledge about tuberculosis transmission Knowledge about TB transmission plays a crucial role to prevent this infection. If the people have good knowledge about the way of the spread of this disease they will be able to practice TB preventive activities. Mesfin, Tasew, Tareke,

11 22 Mulugeta, and Richard (2005) conducted a cross sectional survey to assess knowledge of pulmonary tuberculosis and to determine level of acceptance regarding village based tuberculosis treatment using volunteers among the general public. Their study demonstrated that nearly half of respondents did not know how TB transmitted and several had misconceived ideas about transmission that could potentially create ground for stigmatization of TB patients in the communities. Many misconceptions about transmission, cause and risk factors for the disease are present, perhaps because TB is not openly discussed in homes and communities (Brassard, Anderson, Menzies, Schwartzman, & Macdonald, 2008). Another study Sreeramareddy et al. (2013) found that 32.4% knows TB is transmitted through food, 18.2% knows sharing utensils and 12.3% knows touching a person with TB. Their study also found that knowledge of TB transmission was lower among women, illiterate and rural residents who demographically comprise the majority of the population and knowledge of TB disease was higher among literate persons and urban populations. In addition, correct knowledge about TB transmission was very low among married women in Bangladesh (Khandoker et al., 2011). 2. Knowledge about tuberculosis treatment Knowledge about treatment of tuberculosis disease is an important factor for adherence to a treatment regime. TB treatment is a long time treatment course. If the people are aware about the treatment of disease and its effects people will be easily motivated to seek treatment and adhere to it. Mweemba et al. (2008) found that half of the respondents had good knowledge of TB treatment and a majority of the respondents had a positive attitude toward TB treatment. Knuwaja and Mobeen (2005) conduct a study to determine the level of knowledge about tuberculosis among patients attending family Practice clinics in Karachi. This study s results revealed that only 33% of the respondents were knows that tuberculosis is a curable disease with proper treatment and 31% reported that after cure of the disease a person can live a normal life. Another study Singh et al. (2002) found that only 12.6% knew about the duration of treatment for 6-8 months. Yadav et al. (2006) found that only 6.9% knew about the need of treatment for 6-8 months.

12 23 3. Knowledge about tuberculosis preventive measure Effective preventive measures are essential to reduce tuberculosis (TB) transmission. Gonzaez-Angulo et al. (2013) conducted a study to determine knowledge and acceptability of potential patient-specific TB infection control measures in a rural South African community. Their study results showed that most participants (89%) accepted the wearing of face masks in health facilities, but only 42% of TB suspects and 66% of TB patients (p=.016) would accept wearing face masks at home. Only 68% of participants accepted separate cohorting in health facilities and avoidance of co-sleeping with uninfected household members. Das, Basu, Dutta, and Das, (2012) found 8.62% knew that isolation of patients and (6.03%) avoidance of sharing of food were reported as preventive measures. Another study was conducted by Solliman et al. (2012) to assess the knowledge of tuberculosis among the general population in North East Libya. Their study result shows that 77.4% of respondents knew that avoiding contact with a TB patient can halt transmission of TB. However, 43.4% respondents knew that a healthy diet can prevent TB infection and 68.2% of respondents know that wearing a face mask can prevent transmission of TB from one person to another and 43% of respondents know that a well ventilated home can prevent TB infection. Hashemi et al. (2012) study found that 56.8% of participants knew that covering the nose and the mouth while coughing or sneezing stops the transmission of tuberculosis. Perception factors In this study, the perception factors are focused on Health Belief Model. Its four main construct perceived susceptibility, perceived severity, perceived benefits, and perceived barriers are related to preventive behaviors. These concepts were proposed as accounting for people's readiness to practice TB preventive activities. The combination of severity and susceptibility has been labeled the perceived threat (Glanz et al., 1999). The fear of disease threat and perceived benefits of preventive behavior is stimulating the individual to practice recommended preventive behaviors. So, perception about health and preventive behaviors are interrelated each others. Sokhanya et al. (2008) found that there was significant association between the perceptions with TB preventive behavior. The four concept of perception perceived susceptibility, perceived severity, perceived benefits, and perceived barriers are

13 24 related to TB preventive behavior are stated in below; 1. Perceived susceptibility to tuberculosis Perceived susceptibility of tuberculosis disease may influence the person to perform TB preventive activities. Personal belief and disease susceptibility may differ from person to person. Hashemi et al. (2012) found that most of participants (63%) believed that everyone can be infected by tuberculosis, 67.9% of them believed that tuberculosis is a serious threat and stated that TB is very dangerous. However, only 6.2% of them didn t think it is a dangerous disease. Another study of India Sharma, Malhotra, Taneja, Saha, and Ingle (2007) found that (89.2%) perceived it to be an infectious disease and anyone can get TB. 2. Perceived severity to tuberculosis Tuberculosis has many severe consequences. It affects the physical mental and economical state of the population. Untreated TB can cause death. If people internalize the diseases severity, they will take action to prevent infection. Karim et al. (2010) conducted a study on Community perceptions of tuberculosis: A qualitative exploration from a gender perspective in Bangladesh. Their study findings show that respondents recognized TB as a deadly disease that could affect anyone. The discussants were fairly aware of the psychological, financial and social impacts of TB. Women faced with adverse consequences more often than men, such as trouble in ongoing and prospective marital affairs. Gilani and Khurram (2012) study results found that 73% of respondents perceived TB is a communicable disease and more than 33% of respondents considered that TB affects education, occupation, getting married, and having children. Furthermore, Sikwese (2012) study found that respondents held varying perceptions towards TB. Respondents across all groups perceived TB as being a dangerous disease while some associated TB with HIV. Findings also show that perception of risk was relatively high across all groups as respondents expressed that anyone can contract TB because of the way in which it is spread. Haasnoot et al. (2010) study results showed that 67% of the Maasai population perceived that TB is a danger disease. 3. Perceived barrier of TB preventive behaviors People face huge barriers in accessing TB testing, treatment services, treatment cost, health service center far away from the resident and lack of transportation. Effective

14 25 TB control requires early diagnosis and treatment facilities as close as possible to the homes or working areas so that people can easily access TB diagnosis and treatment services. Thu, Ohnmar, Win, Nyunt, and Lwin (2012) found that most commonly reported barriers to consulting a medical doctor were cost (43%), distance from clinic (21.4%) and difficulty in taking time off from work (13.3%). While working in their current factory, 55.9% of workers had a history of chest symptoms, and of these, 39.5% had sought treatment at a doctor s clinic. Abebe et al. (2010) found that lack of money mainly for transportation and the perception that disease is not harmful and no health facility around were mentioned as reasons for not seeking health care. TB stigma is another barrier of TB prevention. Perceived TB stigma plays an important role for prevention and control of TB. People do not disclose their disease and delay seeking health care for the fear of being stigmatized (Qureshi, Morkve, & Mustafa, 2008). 4. Perceive benefit of TB preventive behaviors People practice preventive behavior when they can internalize that this practice is more beneficial to them and their families. Although acceptance of personal susceptibility to a condition also believed to be serious produces a force leading to behaviors, the particular course of action taken will depend upon beliefs regarding the effectiveness of the various available actions in reducing the disease threat, termed the perceived benefits of taking preventive actions. Hochbaum (1958 cited in Glanz et al., 1999) demonstrated with considerable precision that a particular action to screen for a disease was associated strongly with the two interacting variables of perceived susceptibility and perceived benefits. In conclusion, the literature review and the theory identified the variety of factors that are related to TB preventive behaviors. Among them socio-demographic factors (age, sex and education), knowledge, perceived susceptibility perceived severity and perceived benefit and barrier were related to preventive behavior. These factors are supported by both theoretical concept and research findings. Tuberculosis can be prevented by practicing preventive behaviors but people are not enough concern about preventive practice. Low level of education, knowledge and perception plays an important role to poor practice of TB preventive behaviors. Furthermore, most of the reviewed study was conducted in other countries; there are very limited

15 26 understandings about TB preventive behaviors among Bangladeshi TB patients attendants who are at risk group of developing TB infection. A better understanding about those factors promises an effective nursing intervention to promote TB patients attendants engaging in preventive behaviors aiming at reduce the risk of TB infection. The limitation of information about TB preventive behavior suggests further investigation to identify the factors that are related to TB preventive behaviors.