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close this bookTuberculosis Control in Refugee Situations - An Inter-Agency Field Manual (World Health Organisation, 1997, 72 p.)
close this folder1. TUBERCULOSIS (TB)
View the document1.1 Global Burden of TB
View the document1.2 Natural History of TB
View the document1.3 TB in Refugee Situations
View the document1.4 HIV/TB

1.1 Global Burden of TB

In 1996 there were about 9 million new cases of TB with 3 million deaths, worldwide. These deaths comprise 25% of all avoidable adult deaths in developing countries. 95% of patients, and 98% of deaths, from TB occur in developing countries. 75% of TB patients in developing countries are in the economically productive age group (15-50 years).

The increase the global burden of TB is due to a combination of:

· population growth
· rapid urbanization
· increasing poverty
· spread of HIV (in some regions of the world), and
· ineffective TB control programmes leading to the development of multiple drug resistant organisms.

1.2 Natural History of TB

It is estimated that up to one-third of the world's population is infected with the TB organism. Once infected, a person stays infected for many years, probably for life. The vast majority (90%) of people who are infected with the TB organism do not develop active TB disease. In these healthy, asymptomatic, but infected individuals, the only evidence of infection may be a positive tuberculin skin test.

Transmission occurs by airborne spread of infectious droplets. The source of infection is a person with TB of the lung who is coughing.

Infected persons can develop active TB disease at any time. The chance of developing TB disease is greatest shortly after infection and then steadily lessens as time goes by. Various physical or emotional stresses may trigger the progression of infection to disease. The most important trigger is weakening of immune resistance, especially by HIV infection. TB can affect most tissues and organs, but most commonly the lungs.

Without treatment, after 5 years, 50% of active pulmonary TB patients will be dead, 25% will be healthy (self-cured by a strong immune defence), and 25% will remain ill with chronic, infectious TB.

1.3 TB in Refugee Situations

The number of refugees, displaced persons and other persons of concern to UNHCR was estimated to be more than 26 million in 1996. Over 85% of refugees originate from, and remain within, countries with high burdens of TB.

Refugees are at particularly high risk of developing TB. Coexistent illness and the poor nutritional status of many refugees weaken their immune system and make them more vulnerable to developing TB. The crowded living conditions of most refugee camps facilitate the transmission of TB from infectious patients.

The HIV epidemic affects many countries with large refugee populations, particularly in sub-Saharan Africa. TB notifications have trebled in parts of Africa over the past decade, much of this increase being attributed to the HIV epidemic. Refugee camps in high HIV prevalence countries could be experiencing an even more dramatic rise in TB burden.

KENYA

The incidence of new infectious TB patients in camps was 4 times the rate in the local population.

TB is also a major cause of death in refugee situations.

SOMALIA

In a refugee camp in 1989, one quarter of all adult deaths were due to TB. In two camps in eastern Sudan in 1990, 38% and 50% of all adult deaths were due to TB.

1.4 HIV/TB

In some countries (particularly sub-Saharan Africa), 30-70% of TB patients are infected with HIV. Compared with a non-HIV infected person, an HIV infected person is 25 times more likely to progress from infection to active disease. As well as being at greater risk of developing severe disease, HIV infected people are also at greater risk of developing serious side-effects from TB drugs.

TB is the leading cause of death amongst people infected with HIV. When a HIV /AIDS prevention programme is established in a camp or emergency setting, education on HIV prevention should be provided to TB patients through the TB clinics. TB clinics are also suitable places for the distribution of condoms.

TB patients with concurrent HIV infection respond well to TB treatment but may have more side effects from TB drugs. If a TB patient is infected with HIV, monitor for opportunistic infections, and refer to a doctor for assessment.

TB patients should not be routinely tested for HIV.

The symptoms and signs of TB in patients who are infected with HIV are the same as in non-infected individuals. Spread from the lungs to other parts of the body is common and may result in the severer forms of TB (e.g. meningitis). This is particularly so in children.

Thioacetazone should be avoided because severe, even life-threatening, reactions occur more frequently in HIV co-infected individuals. It is not recommended for use in refugee situations.

RESOURCES

Crofton J, Home N, Miller F. Clinical Tuberculosis, MacMillan,
TALC and IUATLD, 1992
Harries AD, Maher D. TB/HIV: a Clinical Manual. Geneva: WHO: 1996.
WHO / TB / 96.200.


Figure 1 The Natural History of Tuberculosis

Adapted from Crofton J. Et al. Clinical Tuberculosis


Figure 2 Classification of TB