An assignment on Epidemiology covering notifiable disease, tuberculosis and Pulmonary TB

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Epidemiology Assessment

1. What is a notifiable disease? Include website/s with information about notifiable diseases in Australia 

Those health conditions which upon detections are meant to be reported or informed to the public health department are known as notifiable diseases. The compulsory system of reporting these diseases (especially infectious) plays an important role in the prevention and regulation of spreading of that disease to other peoples. Each country and state consists of their specific set of notifiable diseases, which are not static rather keeps on updating according to the needs of the public. These diseases can be categorized on the basis of their urgency of informing the health department. The job of reporting these diseases is usually done by diagnostic laboratories and physicians. It is believed that the majority of notifiable diseases are infectious in nature (Darian-Smith, E., & Lin, 2017). According to the report of Communicable Diseases Network Australia (CDNA) they are certain listed notifiable diseases which have been notified to Common wealth's National Notifiable Disease Surveillance System (NNDSS). Some of these notifiable diseases include anthrax, cholera, dengue virus infection, diphtheria, malaria, leprosy, measles, rotavirus, tuberculosis, and many more. In 1878 Public Health Service, US started collecting data on infectious diseases and further in 1893 it expanded by collecting data related to notifiable disease in the US. Following this process, other countries like India, Australia, China, and the United Kingdom also started this disease surveillance system. Some of the websites which include relevant information about Australian notifiable diseases include-

Department of Health, Australian Government 

Disease notification, NSW Government 

National notifiable diseases surveillance system 


2. What is contact tracing in epidemiology? 

Contract tracing in epidemiology is defined as the process of diagnosis and verification of the individual who has come in contact with the patient suffering from infectious disease. In this activity, it is also ensured that the contact person aware of the exposure and have used the necessary precaution measures. A close observation of these contacts might help them to get effective treatment and care for further spread of the disease's virus (Teo, S., & Tay, 2015). In Australia the contact tracing for Tuberculosis includes the following three basic steps:

Contact identification- After the confirmation of an individual infected from a virus, the relative contacts are then identified by enquiring the activities of infectent/patient (virus infected person) and the activities of the persons who are around the patient since the occurrence of illness (Pareek, Greenaway, & Noori, 2016). The contacts of this TB virus can be either from the family, friends, colleagues, and health care providers. 

Contact listing- The listing of all the persons who come in contact with the infected person are done as contacts. Every possible effort is made to identify each contact and make aware of their disease or contact status. This help in providing early care to the contacts if they develop any symptoms of TB. Apart from this, the listed contacts are also provided with required information related to prevention and precaution of TB.

Contact follow-up- Consistent monitoring of the contacts are done for observing their symptoms of TB infection. 


3. Please download Tuberculosis Contact Tracing guidelines for the Northern Territory and Victoria. Can you identify any important differences? 

Tuberculosis Contact Tracing guidelines for Northern Territory is the written document for guiding the health professionals in treatment, diagnosis, and controlling of tuberculosis. The first edition of this guidelines was released on February 1991 and the latest and revised edition was released on May 2016    The various chapters within this guidelines include diagnosis of TB, BCG vaccine, treatment of TB, latent TB infection, contact tracing and screening in a community and special groups in the high risk areas. The primary goal of this approach is to provide the left out victims of TB with the benefit of the active LTBI or TB as soon as they are identified. The basic aims of this contact tracing includes:

Identifying the latest cases of active TB patients and starting their treatment.

Identifying the infected contacts on TB by using Mantoux testing for offering treatment of LTBI.

Recognising the source case where there has been a recent case of TB occurrence.

Identifying the source case where there has been an incident of extra pulmonary disease. 

Recognising the areas and groups in need of community screening.

Providing requisite and relevant education and information related to TB.  

The steps involved in contract tracing includes- 

Categorising the patients according to the degree of infection level.

Identifying the contacts and arranging the contacts on the basis of estimated risk level, viz., low, medium and high.

Examining all cases of high risk contacts of the pulmonary TB.

Then the examination of medium risk contacts is done followed by low-risk contacts based on the outcome of high risk screen.

The regional TB health care staff has to travel the TB diagnosed community for educating friends and family (Baird, Donnan, & Coulter, 2018). 

On the other hand, Tuberculosis Contact Tracing guidelines for Victoria is based on the Peter Doherty Institute for infection and immunity.

The primary aim of contact tracing for this guidelines includes-

Identification of other people who might have been infected with contact of the person suffering from TB.

Counselling the people diagnosed with TB infection and providing them with the treatment for LTBI.

Identification of further cases of TB within those in contact with the recognised cases.

The TB health care staff are advised to undergo the following steps according to the Victorian guidelines-

Categorising the case according to infectiousness viz., high infectiousness, medium infectiousness and low infectiousness. The sputum smear positive of high infectiousness is positive and for medium infectiousness is negative and for low infectiousness is also negative. 

The infectious period is then determined for identifying the priority groups of contact tracing. Overall, the infectious period is considered 3 months prior to the TB diagnosis until the date of any symptom onset.

Assigning the priority in screening based on high risk group, medium risk group and a low-risk group.

4. A student at a secondary school in a small community has been diagnosed with smear-positive pulmonary TB while being hospitalized. The news has been published in a local newspaper. There has been considerable anxiety in the local community and parents of the other students. Only the parents and 8-year-old brother are identified as contacts, and no evidence of TB is found among them. As the responsible Public Health officer, you want to give helpful information in an informed but not over-technical form. You might tell the community what they should know, without raising panic or encouraging complacency. You are required to prepare a report for the local media and community to address their concerns. Please include in the report

i) What is the disease burden of TB in Australia? (e.g. incidence, prevalence, mortality )

Since the year 1980, Australia is one of the nations to have the lowest rate of TB all over the world. However, 1425 cases related to TB has been identified in 2017 in Australia, along with 533 cases of them notified in the NSW. Over the last decade, there has been a record of 171 TB identifications in the Australian Act Territory (ACT). The trends have been seemed to be increasing with the increase in the number of notification over the passage of time. The age of the TB patients ranges from 14 to 91 years (median age of 36 years) and there are approximately 53.8 percent cases with male patients. It is identified that most of the TB cases (approximately 84.2 percent) were born abroad. However, in the case of Australian born TB (30.8 percent) the major risk factor is commonly the household contact. Similarly, for foreign-born TB (86.9 percent) the major risk factor is past residence or travel in a high TB risk country. On a whole, of all the notified TB cases in Australia 82.4 percent of the cases had undergone successful treatment.

 ii)  How is pulmonary TB transmitted & how infectious is it? (High, moderate, low) 

The pulmonary TB is produced by the bacterium Mycobacterium tuberculosis (M tuberculosis). This bacteria s highly contagious and infectious which can spread easily if it is not diagnosed, isolated and treatment immediately. TB is basically an airborne disease which can infect through the breathing of an infected person in the air. The various modes of air contamination includes breathing, coughing, signing, talking, and sneezing. These activities, However, not every individual who comes in contact of the TB virus develops tuberculosis (Parvaresh, Bag, & Cho, 2018). People with low or weak immune system (example, people with HIV or diabetes) are easily prone to develop active TB disease. The longer time period spent with the patient the higher is the risk of catching TB virus. Tuberculosis germs do not stick to skin or clothing but only move in the air. Thus, hugging, shaking hands, sharing cloth or towel, and eating with the infected person does not transmit tuberculosis bacteria. There are generally two types of TB disease, viz., Latent Tb and Active TB. In latent TB, the immune system of the does not allow the TB germ to spread further. In Active TB the germs get multiplies by itself and spread all over. Pulmonary TB is also considered to be infectious based on its various level of risk factor:

High- when in close contact with the patient since last 3 months.

Medium- there is frequent contact but it is less intense.

Low- Contact except for family which includes friends, colleagues, and health care staffs.

iii) Who are the high risk groups for contact tracing, and in what clinical circumstances should more distant contacts or other members of the community present to the clinic for testing? 

The high risk group in the contact tracing of tuberculosis includes the close contact individuals with the TB patient having smear-positive TB. The high risk groups in contact tracing includes two categories i) individual having a higher risk of getting in contact with TB, ii) individuals having higher risks of generating TB disease. High risk people are the close relatives who lives within the same household, especially family. Sometimes the people who spend maximum time with the patient (friends and co-workers) are also at high risk. Infants, adolescents and small children exposed to the high risk people (patents) are at a higher risk to develop the TB disease. Persons having a weak immune system or suffering from diseases like diabetes, immunosuppressant, rheumatoid, leukemia, arthritis, kidney failure, HIV infection, silicosis, and lung cancer have also the higher tendency to get infected from TB virus. Similarly, a person has a past history of unsuccessful treatment of TB in last 2 year have also the higher tendency to develop the disease again. TB transmission usually occurs to the family when the room is small and overcrowded without sufficient ventilation. In such cases, the concentration of bacteria within the room is high, with an increase in risk for the contacts.

iv) What procedures have been taken for the identified contacts, including follow-up 

The foremost procedures followed for the identified contacts of tuberculosis includes the following initial assessment- 

Medical evaluation- the medical history, the travel history, contact history with TB patients are identified for each contacts. These data are then well evaluated for a thorough symptom review along with the physical examination.

Tuberculin skin testing- this test is necessary for the evaluation of contact investigation. Each identified contact has to undergo this test to determine the presence of M tuberculosis bacteria. The TST test is also recommended if the patient has received BCG vaccination. The TST test is preferred to conduct within 3 weeks of the flight to get a baseline measurement. 

Potential contacts at higher risk- Contact having a higher risk of developing active TB disease required immediate medical evaluation and treatment. The treatment includes the chest radiograph and the follow-up, irrespective of the TST result (Atif, Sulaiman, & Shafie, 2014). 

TST conversion- Contacts having a negative result of TST which become positive after the second TST test are expected to be infected from the index case. These cases require very careful and prompt medical treatment and evaluation for identifying the possibility of active tuberculosis.


v) When would the index case student return to class & how does the community know they are safe from infection from this source? 

Once the course of treatment of the child is finished, his parents should make other medical tests to make sure that he has completely recovered from TB. It is sometimes possible to catch TB more than once, so the parents should always have a close observance on the child' health condition (Globan, Lavender, & Leslie, 2016). Parents need to send their child to school only after complete confirmation of successful TB disease treatment. If there is still some virus remaining, then the patient should be kept in the hospital in isolation. There is still a possibility of catching TB virus to contacts after the patient gets cured. The virus enters in the body in form of ‘Latent TB' which are inactive in nature but can become active in future. So, for this case, the contact can take Isoniazid antibiotic pill at least for 9 months. To counter-effect the effect of isoniazid, Rifampin can be taken for 4 months. These medications should be taken by the contacts (parents, classmates, and teachers) under the supervision of a doctor to avoid the possibility of Active TB. Before providing such medicines to close contacts, there is a need to have a close monitor of any kind of TB symptoms. Tuberculin skin test (TST) or interferon or the quantiferon tests can be done on the close contacts if any symptoms are observed. Latent TB infection screening can also be done to identify the presence of latent TB virus. 

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