Notifiable disease

Discuss about the Public Health Epidemiology Disease.

Tuberculosis, an infectious disease caused by Mycobacterium tuberculosis is prevalent worldwide with about one-third carrying the bacteria. Out of this, only 10-20% are living with active tuberculosis. People with active infection have higher chance of spreading the disease compared to those with latent TB infection. The rate of tuberculosis infection was 5-6 cases per 100,000 Australian in 2010 and now about 1200 cased of tuberculosis is reported everywhere in Australia (Health.gov.au, 2016). This disease can be controlled by early detection and contact tracing assessments on infected group of people. Therefore, as Public Health Officer within Australian Health Department, this report provides insight into the appropriate method for contact tracing and exposure assessment for a notified TB index case.

Notifiable diseases are those diseases where it is legally necessary to report about such disease to key government authority in a country. This is useful for proper screening and surveillance of the disease so that the key health authority takes appropriate action to prevent the outbreak of the disease in the community. To report about notifiable disease, the National Notifiable Diseases Surveillance System was established in Australia to keep records of such diseases. Some example of notifiable disease in Australia includes AIDS, cholera, hepatitis, tuberculosis, yellow fever and many others (Milton et al., 2012).

The websites providing information about notifiable disease in Australia are as follows-

• The Australian Government Department of Health Website – https://www.health.gov.au/casedefinitions
• The National Notifiable Disease Surveillance System website of Australia- https://www.health.gov.au/cdnareport

The National Disease Surveillance System of Australia website publishes fortnightly reports of Communicable Disease Network Australia (CDNA). CDNA shares this report and evaluates the communicable disease surveillance in Australia. The report covers the outbreak of disease and level of health department coverage to prevent the epidemic (Department of Health | National Notifiable Diseases Surveillance System, 2016).

Tuberculosis disease mainly affects the lungs leading to pulmonary symptoms and when it affects the disease outside the lungs, it leads to extra-pulmonary symptoms. The general symptoms of the disease are weight loss, fatigue, sweating, fever and night sweats. The specific pulmonary symptoms may be symptomatic like chest pain and consistent cough with sputum. However, majority of people with this disease have no symptoms leading to massive bleeding due to erosion of pulmonary artery. On the other hand, extra-pulmonary symptoms include the infection in specific sites like pleura, urinary system, central nervous system and many others. These symptoms are mainly observed in immune-suppressed person and children as their weakened infection exposes them to greater risk of developing the disease (Antune et al., 2016).

Symptoms of tuberculosis and disease burden in Australia

According to the Notifiable Disease Surveillance System report, the incidence of tuberculosis in Australia was 5.8 cases per 1 lakh population in 2012 and 5.5 cases per 100, 000 populations in 2013. The majority of TB notifications were seen in migrant population and ethnic group. Therefore, the incidence of TB is mostly low in Australia. The estimates of Australian TB burden in terms of mortality rate due to TB and HIV includes 0.02 per 1, 00, 000 population. The incidences of TB were found to mostly increase by age both in males and females. In 2015, about 1254 total case of the disease were identified. Australian Health Department has done a lot to reduce the global burden of the disease by achieving 87% treatment coverage by 2015 (WHO estimates of TB burden, 2016).

In epidemiology, contact tracing is a method of assessment to identify people who have come in contact with affected person suffering from communicable disease. The person with infectious disease is called index patients. This is an effective method to control and prevent infectious diseases like HIV and tuberculosis. In case of sexually transmitted disease, partner notification is also done in contact tracing to identify the sexual partners of affected person. The person doing assessment has knowledge of all possible ways by which a person is exposed to the disease or comes in contact with affected person. Contact tracing provide steps to disease identification and active surveillance in affected population. A person is designated as coming in contact with the disease only after proper assessment and identifying that the person was in physical proximity with the index patient who is living with active infection. Conducting contact tracing assessment is essential in epidemiology for early diagnosis and early initiation of treatment process in an individual. This will also serve to eliminate strategy for secondary prevention of disease. It also serves the role of maintain public health through limited outbreak and transmission of disease (Kasaie et al., 2014).

According to International Standard for TB care, all health care providers have the responsibility to ensure that that children and adults in close contacts with people having tuberculosis is evaluated according to International recommendation. Therefore contact tracing is essential for health professionals and their priorities for action are dependent on level of contact. For example people with HIV and those who are exposed with positive pulmonary patient’s smear are at greater risk of acquiring TB infection, whereas children under 5 years and people with suppressed immunity had high risk of developing active TB (Millet et al., 2013). With this context, the steps for contact tracing for TB in Australia are as follows:

• The contact tracing assessment is done 14 days after a patient is diagnosed with tuberculosis. The contact tracing assessment depends on geographical location. For example in Pacific Island country, tuberculin skin testing is done for contact assessment and other areas biological assays or chest x-ray is done to monitor patients.
• In case of location where performing tuberculin skin testing or other assays are not possible, then contact tracing assessment is done by clinical assessment of patients to identify contacts. On identification of person prone to infection by contact, isoniazid preventive treatment is given to prevent infection to tuberculosis disease.
• The first steps for health staffs for contact tracing is to assess all members for symptoms of tuberculosis infection.
• The infection of tuberculosis is identified through TB suspect criteria which are as follows:
• Person with symptoms suggesting TB infection such as productive cough for more than two weeks, loss of appetite, fever and night sweats.
• TB suspect determined by age, HIV status and prevalence of the disease in local population.
• The presence of three of the following symptoms also suggest diagnosis of TB which are chronic symptoms of disease, physical signs of TB, positive tuberculin test and chest ray indicating TB (Teo et al., 2015).
• The next step is to collect sputum samples from suspected person and carry further investigation according to National TB Programme protocol of Australia.
• If any contact person is identified, then they are registered with National TB programme and treating them according to national treatment guidelines.
• People with active TB are excluded and those with suggestive contact TB are given isoniazid preventive therapy for 6-9 months. For children under 5 years, this therapy is given for six months only.
• The guideline for preventive treatment with isoniazid is to directly observe all patients, observe patients for adherence and side-effects and regular follow-up with the patients.
• In case of children with asymptomatic TB infection, paediatric assessment is done by medical history and physical examination.
• In case of individual who have no signs and symptoms indicating TB infection, health education is given to make them aware about early signs and symptoms of disease (Goebel et al., 2015).

Contact tracing in epidemiology

In case of areas, where tuberculin skin testing is done for contact tracing assessment, then all house members are given tuberculin testing. The other key steps for contact tracing through tuberculin skin testing are as follows:

• In case of people with previous treatment or history of TB, tuberculin skin test is not required and in this case assessment is done to identify signs and symptoms indicating the disease.
• Tuberculin skin test is not given to children under five years of age and to prevent active infection, such children are given 6 months isoniazid preventive therapy when they come in contact with index patients.
• Tuberculin skin testing is also not given to HIV infected person as they are very likely to be falsely negative in skin testing.
• In case of other HIV negative individual and people above 5 years of age who are found with 5-10 mm of tuberculin skin testing, the National TB programmes provides isoniazid preventive therapy (Viney et al., 2015).

A recent event in a small community in Australia depicts the public burden of tuberculosis and its vulnerability to other population in a community. The incident was published in a local newspaper in a small community in Australia where a school student hospitalized in hospital for health issues was additionally diagnosed with smear positive pulmonary TB. Smear positive cases of TB infection are more risky for other people living in close proximity with affected person in community (definitions, 2016). This risk factor concept has increased anxiety of local community and parents of other students living in the local community after the diagnosis of 8 year old boy with TB during the hospitalization. With this context of public health issue in Australia, this report gives information in identify household contact with the disease and the steps to prevent transmission of infection to other people.

Tuberculosis, the chronic infectious disease of the lungs is mainly spread through living in close proximity or contact with people with TB. People who are at high risk of developing TB falls into two categories-

Person with recent infection with the bacteria such as person with close contact with infection, children of less than 5 years with positive TB test, homeless person, HIV infected person, health professionals and injection drug users. They are also high risk group for contact tracing.

Person with weakened immune infection like HIV infection, kidney disease, low body weight and those undergoing treatment for organ transplant and Crohn’s disease.

Tuberculosis is a global disease burden worldwide with 1.4 million death reported in 2010. The situation of TB infection in Australia has remained relatively stable and currently there are 1254 notifiable cases of TB in Australia in 2015. The rate of tuberculosis infection is found more in infectious and indigenous group. It is necessary that the National TB programme of Australia take immediate steps to prevent active infection in other group in the community.

After the incidence of the 8 year old boy diagnosed with smear positive TB in local community, it was necessary to identify other household members who had chance of contact with the disease. The contact tracing and exposure assessment was done for the household. The procedure for identifying household contacts were the same as mentioned above in the national guideline for conducting contact tracing for TB. After the contact tracing and exposures assessment, it was found that only the parents of the child and his 8 year old brother was identified as contact and they had no evidence of TB. Hence for identified household contacts, further examination and diagnostic testing like chest radiograph for TB was done. Children below 5 years are in the high priority group for medical evaluation as they have more vulnerable to invasive infection of TB. As household contacts identified for the child’s family included only their parents and his 8 year old brother, they came under medium priority contacts. Their treatment and evaluation is done as mentioned in the diagram. The main preventive treatment is isoniazid therapy for a period of six months 8 year old brother and for 9 months for the parents.

Steps for contact tracing for TB in Australia

Evaluation and treatment of medium priority contact. Source: (Guidelines for the Investigation of Contacts of Persons with Infectious Tuberculosis Recommendations from the National Tuberculosis Controllers Association and CDC, 2016)

The student diagnosed with smear positive pulmonary TB will have to take the exclusive drugs for TB everyday for six months. The relapse can occur if they become culture positive again after their treatment. The child can join the school when he is no longer infectious after starting treatment and taking medications. There is claim that patients are not infectious after 2 weeks of treatment, however patient’s sputum is infected with the mycobacteria for many weeks even after the therapy. Many other patients like the child with smear positive infection is released after 2 weeks of medical therapy. As the level of drug resistance differs from person to person, therefore teachers and parents should also take preventive treatment to avoid being diagnosed with the disease (Pietersen et al., 2014).

The procedure for contact tracing in Northern territory starts with classifying the case according to degree of infection and then making a list of contacts according low, medium and high risk. Then all high risk contacts of TB are evaluated first followed by medium and low risk contacts. In case of TB diagnosis in aboriginal community setting, education is given to them to do proper contact tracing (Guidelines for the control of Tuberculosis in the Northern Territory, (2016). The method of classifying priority in TB contacts is same for Victoria, the only difference is seen in clinical evaluation. In Northern Territory, it is done by mantoux test and chest X-ray, while in Victoria, it is done by tuberculin skin testing and interferon gamma assays. The Victorian Tuberculosis Program is under the jurisdiction of CDNA and Northern Territory contact tracing guideline is under the jurisdiction of Northern Territory Centre for Diseases Control (Guidelines for the control of Tuberculosis in the Victoria, 2016).

Reference

Antunes, L. B., Tomberg, J. O., Harter, J., Lima, L. D. M., Beduhn, D. A. V., & Gonzales, R. I. C. (2016). The user with respiratory symptoms of tuberculosis in the primary care: assessment of actions according to national recommendations. Northeast Network Nursing Journal, 17(3), 409-415, Link- https://www.revistarene.ufc.br/revista/index.php/revista/article/view/2280

definitions, C. (2016). Case definitions. Ncbi.nlm.nih.gov. Retrieved 15 November 2016, from https://www.ncbi.nlm.nih.gov/books/NBK138741/

Department of Health | National Notifiable Diseases Surveillance System – current CDNA fortnightly report. (2016). Health.gov.au. Retrieved 15 November 2016, from https://www.health.gov.au/cdnareport

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Guidelines for the control of Tuberculosis in the Victoria, (2016). Retrieved 16 November 2016, from https://www2.health.vic.gov.au/about/publications/policiesandguidelines/tuberculosis-guidelines-2015

Guidelines for the Investigation of Contacts of Persons with Infectious TuberculosisRecommendations from the National Tuberculosis Controllers Association and CDC. (2016). Cdc.gov. Retrieved 16 November 2016, from https://www.cdc.gov/Mmwr/preview/mmwrhtml/rr5415a1.htm#fig7

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Millet, J. P., Moreno, A., Fina, L., Del Baño, L., Orcau, A., de Olalla, P. G., & Cayla, J. A. (2013). Factors that influence current tuberculosis epidemiology. European Spine Journal, 22(4), 539-548, Link- https://link.springer.com/article/10.1007/s00586-012-2334-8

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Pietersen, E., Ignatius, E., Streicher, E. M., Mastrapa, B., Padanilam, X., Pooran, A., … & Warren, R. (2014). Long-term outcomes of patients with extensively drug-resistant tuberculosis in South Africa: a cohort study. The Lancet, 383(9924), 1230-1239, Link- https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)62675-6/abstract

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