PREDICTING TUBERCUIOSIS CASELOAD WITH THE ANNUAL RISK OF TB INFECTION IN CAMBODIA, 1995-1996

Norval PY 1, Roustit C 2, Kong Kim San 2

1 World Health Organization, Phnom Cambodia

2 National Tuberculosis Program, Ministry of Health, Phnom-Penh, Cambodia

 

Background: Tuberculosis (TB) surveys were conducted twice in Phnom Penh in 1995 and 1996 and once in the country in 1995 to estimate the prevalence and the annual risk of tuberculosis infection (ARTI).

Methods: Representative sample in schoolchildren aged 5 to 9 in Phnom Penh and in all provinces, with the exception of the unsafe zones. Intradermal tuberculin test PPD RT23 / Tween 80 1 TU was applied to 2861 children with no BCG scar in 1995 and PPD RT23 / Tween 80 2 TU to 2371 children with no BCG scar in 1996. Based on tuberculinic surbeys, it has been possible to calculate the prevalence rate.

Results: The ARTI is estimated to be 1.2% in Phnom Penh and 1.1% in Combodia in 1995 with 1 TU and 8 mm cut-off point ARTI in Phnom Penh is 1.5%. Mirror image techniques confirm results. The difference between 1995 and 1996 in Phnom Penh is not statistically significant (p>0.05).

Conclusion: The ARTI is equally distributed in cities and rural areas of Cambodia. Results with RT 23 1 TU and 2 TU are similar. The prevalence of infection has declined 1.9% per year from 1955 to 1995 in Phnom Penh and in the rest of the country. Case notification and estimates for smear positive cases in Cambodia in 1995 is respectively 118 and 251 per 100,000 inhabitant corresponding to 2.3 to 4.8 times the ARTI estimates. Predicting the number of TB cases based on ARTI is not possible in Cambodia and should be replaced by prevalence survey.

 

 
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