Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.
The distribution of TB
Clicking on the link for each source of data will bring it up in a new page
World data
According to the WHO (World Health Organisation),
- Someone in the world is newly infected with TB bacilli every second.
- Overall, one-third of the world's population is currently infected with the TB bacillus.
- 5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life.
- People with HIV and TB infection are much more likely to develop TB.
The table below shows that in 2005 worldwide there were nearly 1.6 million deaths from tuberculosis, and over 14 million people infected by the disease.
|
Incidencea |
Prevalencea |
TB Mortality |
|
All forms |
Smear-positiveb |
|
|
|
|
WHO region |
number (thousands) |
per 100 000 pop |
number (thousands) |
per 100 000 pop |
number (thousands) |
per 100 000 pop |
number (thousands) |
per 100 000 pop |
(% of global total) |
Africa |
2 529 (29) |
343 |
1 088 |
147 |
3 773 |
511 |
544 |
74 |
The Americas |
352 (4) |
39 |
157 |
18 |
448 |
50 |
49 |
5.5 |
Eastern Mediterranean |
565 (6) |
104 |
253 |
47 |
881 |
163 |
112 |
21 |
Europe |
445 (5) |
50 |
199 |
23 |
525 |
60 |
66 |
7.4 |
South-East Asia |
2 993 (34) |
181 |
1 339 |
81 |
4 809 |
290 |
512 |
31 |
Western
Pacific |
1 927 (22) |
110 |
866 |
49 |
3 616 |
206 |
295 |
17 |
Global |
8 811 (100) |
136 |
3 902 |
60 |
14 052 |
217 |
1 577 |
24 |
aIncidence - new cases arising in given period; prevalence - the number of cases which exist in the population at a given point in time.
bSmear-positive cases are those confirmed by smear microscopy, and are the most infectious cases.
pop indicates population.
From the figures above, you can see that:
South-East Asia had the highest total number for the incidence of new cases of the disease, the highest number of active TB sufferers and the highest total prevalence in the population at that time, but not quite the highest mortality.
Africa had the highest numbers for each of these indicators when expressed per capita (i.e. allowing for population size).
UK data
The data (for active TB) used in the figure below are taken from the HPA summary
Sources: 1988*, 1993*, 1998 National Tuberculosis Survey; 1999 - 2005 Enhanced Tuberculosis Surveillance
* scaled up from 6 month survey
This shows that, although TB is no longer common in the UK, since the mid-1980s the number of cases reported each year has risen to around 8,000.
Every year about 350 people in England die from TB. In 2002, there were 384 deaths associated with tuberculosis.
Extracted from NHS Immunisation Information
"the most comprehensive, up-to-date and accurate source of information on vaccines, disease and immunisation in the UK".
Tuberculosis notifications and deaths in England and Wales 1984 to 2000
Sources: Enhanced Tuberculosis Surveillance, Labour Force Survey population estimates
Prepared by: Health Protection Agency Centre for Infections
Data and explanation below extracted from: Key Health Data for the West Midlands 2005
Rates of tuberculosis in the West Midlands by ethnic group
Further explanations (from source above):
Over 50% of cases of tuberculosis occur in people of Indian Sub-Continent origin (Indian, Pakistani and Bangladeshi ethnic groups). The next highest proportion is in the White ethnic group, accounting for 22% of all cases.
Rates of tuberculosis are, however, highest in the Black African ethnic group. Rates of disease have been increasing rapidly in this ethnic group and have made a substantial contribution to the overall increase in tuberculosis in the West Midlands. Measured rates may, however, be distorted by a rapid short term increase in this sector of the population and therefore the numbers of cases, as rates are measured against a constant (mid-2001) denominator.
In 2004 64% of patients diagnosed with tuberculosis were born abroad, and of these nearly 50% had entered the UK within the last 5 years. The number of tuberculosis patients born abroad has increased by 15% since 2000 with the percentage being diagnosed within 5 years of entry to the UK almost tripling.
Some questions
By what percentage has the number of reported TB cases in England and Wales risen between 1988 and 2005?
> 72.5 % (4659 in 1988, 8037 in 2005: total increase 3378, divided by start value 4659, X 100)
How can you explain the statements that 22% of cases of tuberculosis occur in White ethnic group, and Over 50% of cases of tuberculosis occur in people of Indian Sub-Continent origin, but Black Africans show up much more on the bar graph?
>These figures are percentages of the total (West Midlands) population, whereas the graph is per capita (OK per 100,000).
Why do you think that the number of cases for Black Africans shows such a rise?
>More recent immigrants? - see the table at the top of the page
More Web references
Tuberculosis numbers 'level off' [BBC news story - response to WHO statement]
March 2007 Tuberculosis update [Health Protection Agency]
Health & care Highlights [Breakdown of TB data by region 2004 vs 1994]
Five cases of TB at family centre [BBC news]
All those affected attended a family centre in the Ely area of Cardiff
Parents in a suburb of Cardiff have been contacted by health experts after a childminder and four children were diagnosed with tuberculosis.
Cases of Tuberculosis rise steeply during 2005
HPA Press Release 2 November 2006