Figure 1

For North America, most of Western Europe, Australia and New Zealand, the burden of TB is generally the lowest in the world with estimated incidence rates of TB disease below 15 cases per 100,000 population.

Greenland has an estimated rate of between 100 and 199 cases per 100,000 population.

For the majority of the countries of South America the estimated incidence rate of TB disease is under 50 per 100,000 population. For Peru, Bolivia, Guyana, and Surinam, however, the incidence rate is between 50 and 99 cases per 100,000 population.

For the Russian Federation and parts of South East Asia including India, the 3 year average incidence rate is also between 50 and 99 per 100,000 per population.

China has a reported estimated average incidence rate of between 15 and 49 per 100,000 population. Other smaller countries of the Western Pacific Region, including Indonesia, Malaysia, North Korea and the Philippines have estimated incidence rates between 100 and 199 cases per 100,000 population. Cambodia the highest estimated TB rates in this region at over 199 cases per 100,000 population.

The African continent has a varied distribution of estimated incidence rates with the lowest rates in the north and the highest in the south. The northern region has the lowest estimated incidence rates on continental Africa at less than 50 cases per 100,000 population. Moving south, the estimated rates start to increase to between 100 and 199 cases per 100,000 population. The estimated TB rates for the southern region of Africa including Botswana, Namibia, South Africa, Zambia and Zimbabwe are over 199 cases per 100,000 population the highest estimated rate in Africa and in the world

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Figure 2

The figure is a decision making model to guide TB Testing in Travellers pre and post travel.
Following a pre-travel assessment the decision as to whether a traveller should have a post-travel TST is based on a) the anticipated exposure risk and b) the individual traveller's risk of TB activation.

A) Anticipated Exposure Risk

For the anticipated exposure risk, decision is based on the smear positive TB incidence rate of the destination country and the duration of visit of the traveller in that country. If any one of the following 4 exposure criteria is met then it is recommended that the candidate have a post-travel TST 8 weeks after leaving the high TB incidence area:

1. Smear positive rate is > 200 per 100,000 population in the destination country and the duration of the visit is three months or more
2. Smear positive rate is between 100 and 199 per 100,000 population in the destination country and the duration of the visit is six months or more
3. Smear positive rate is between 50 and 99 per 100,000 population in the destination country and the duration of the visit is twelve months or more.
4. Smear positive rate is > 50 per 100,000 population in the destination country and the duration of the visit is one month or more of health care work.

B) Individual traveller risk of TB activation

Based on the individual characteristics, if the traveller has any of the following characteristics which are associated with an increased risk of TB activation, and exposure to TB is greater than routine tourist activities but not necessarily meeting 1 of the four exposure criteria listed above, then it is recommended that a post-travel TST after 8 weeks leaving the high incidence country be done:

1. Substantial immune suppression (those considered high risk according to Table 1)
2. Traveller is undergoing treatment with glucocorticoids, patient taking Tumour necrosis factor (TNF) alpha inhibitors or
3. If the traveller is less than 5 years of age

Pre-Travel TST

If the candidate meets the criteria for post-travel TST either through the exposure categories or because of characteristics association with TB activation, as listed above, then a decision will be made to determine whether the traveller should have a pre-travel TST.

If one of the 3 criteria below are met then a pre-travel TST is recommended.

1. If it is anticipated that the individual will have routine TST surveillance, for example if the individual is a health care worker, it is recommended that a baselines two-step TST according local occupation health protocol be performed
2. If the traveller is at risk for liver disease (for example: hepatitis C or excess alcohol use and has an increased probability of prior TST positivity (for example born or lived in high TB incidence country, health care worker, Aboriginal) then a pre-travel TST is recommended and if feasible a two-step test.
3. If the traveller is 50 years of age or older and has an increased probability of prior TST positivity (for example born or lived in high TB incidence country, health care worker, Aboriginal) then a pre-travel TST is recommended and if feasible a two-step test.

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