[Tuberculosis epidemiology in area 15 of the Spanish autonomous community of Valencia: evolution from 1987 through 2001]

OBJECTIVES

To describe the evolution of tuberculosis epidemiology in Area 15 of the Autonomous Community of Valencia.

MATERIAL AND METHODS

Cases of tuberculosis were identified by active case finding in Area 15 from January 1987 through December 2001. Clinical and epidemiological data were extracted from case records and a patient interview.

RESULTS

Four hundred seventy-six diagnosed cases of mycobacterial infection were identified (459 tuberculosis, 16 atypical, and 1 mixed); 423 tuberculosis patients were residents of Area 15. The mean annual incidence rate was 24.6/100 000 population, representing a rate decrease of 41.5% from 1990. The most frequent risk factors were smoking (38%), alcoholism (20%), human immunodeficiency virus (HIV) infection (18%), and contact with a tuberculosis patient (14%). The site of tuberculosis involvement was the lung in 61% (49% bacillus positive, with a nonsignificant trend to decrease over time), nonpulmonary in 26%, and mixed in 13%. The radiographic pattern observed most often was pulmonary infiltrates (67%), and lower lobe involvement tended to increase over time. Diagnosis was by acid-fact bacillus stain for 77%, clinical picture for 16%, and histological for 7%. Isoniazid resistance was detected in 1.5% and rifampicin resistance in 0.3%. Patients were hospitalized during diagnosis in 79% of cases; the mean stay was 18 days.

CONCLUSIONS

The incidence of tuberculosis has decreased in spite of the HIV pandemic. Risk factors have not changed, bacteriological diagnosis has improved, and the location of pulmonary infiltrates has changed. No influence of immigration on the incidence rate of tuberculosis has been detected to date.

Impact of the human immunodeficiency virus on the epidemiology of tuberculosis in area 15 of the Valencian community in Spain

SETTING

Area 15 in Valencia.

OBJECTIVES

To describe the epidemiology (1987-2001) of tuberculosis (TB) in human immunodeficiency virus (HIV) patients.

METHODS

Study of annual incidence, age distribution, excess cases attributed to HIV, etiological risk fraction (ERF), population attributable fraction (PAF) and f factor.

RESULTS

Of 476 cases diagnosed, 459 were TB, 16 environmental and one mixed; 76% of environmental cases were HIV-positive (P < 0.001). There was a mean annual TB incidence of 24.6/100000, with an annual reduction of 4%. Seventy-three patients were HIV coinfected (16%) (mean incidence 3834/100 000 seropositives). The principal risk factor was drug use (59%) for HIV+ and contact with TB for HIV-. We found no difference in pulmonary or extra-pulmonary location between groups, contrary to mixed cases (P < 0.001). In HIV+ there was a lower frequency of infiltrates (P < 0.001) and cavitation (P < 0.01), and a higher frequency of adenitis (P < 0.001), miliary or nodular pattern and normal X-ray (P < 0.001). Seropositives had a 174 times higher probability of developing TB. The mean ERF attributed to HIV was 99%, the PAF was 16% and the f factor was 1.19. Highly active antiretroviral therapy (HAART) reduced the risk of TB in HIV+ by 80%.

CONCLUSIONS

TB has continued its decline, although HIV generated an excess of cases in the 1990s. HAART has reduced the TB risk in HIV+ and possibly the overall rate of TB.

[Microepidemics of tuberculosis; apropos of 2 school outbreaks in the area 15 of the Valencia community]

Schools are settings with high concentrations of young people with little exposure to Mycobacterium tuberculosis and greater risk of developing disease when infection occurs as the result of sporadic localized outbreaks. We studied two outbreaks in two elementary schools (A and B) after two cases of bacilliferous pulmonary tuberculosis were detected in teachers in 1990 and 1994. Contacts were trace din school A by the primary care physician and in school B by the pneumologist and public health authorities. Contacts were classified as belonging to the risk group (RG) or the low risk group (LRG). The RG was composed of 187 contacts in school A and 59 in school B. Individuals in the LRG numbered 429 and 116 respectively. Mantoux positives numbered 108 in the RG and 45 in the LRG in school A (p < 0.001). In school B 50 RG individuals and 29 LRG individuals were positive (p < 0.001). The proportion of Mantoux positives was greater in the RG of school B than in the RG of school A (p < 0.01), probably owing to longer time of evolution of disease and possible laryngeal involvement in the index case. Likewise, tuberculin positives were fewer in the LRG of school A than in the LRG of school B (p < 0.001), owing to the small size of the LRG in school A. Thirteen cases of tuberculosis were seen in school A, six of which called for drug prophylaxis after contacts were traced. The nature of the index case and the conditions of exposure are both important in such outbreaks, demonstrating the need to act appropriately to trace contacts, preferably under the supervision of a pneumologists.