Tuberculin skin test among medical college students

The incidence of active tuberculosis in Japan has markedly decreased in the past few decades. It is also reported that the prevalence of tuberculosis infection in young population has been decreasing in accordance with the decline in the overall occurrence of tuberculosis. The above mentioned facts indicate that the younger population has a greater risk of developing tuberculosis once exposed to tuberculosis infection. Actually, the epidemics of tuberculosis among the adolescent population have often been reported in recent years. We performed a tuberculin skin test on our medical college students, who might be exposed to tuberculosis infection during their student clinical internship, in order to obtain the information about their present status of reaction to the tuberculin skin test. The data obtained from students between 18 and 25 years old were analyzed using Student's t test and Kruskal-Wallis's method. The mean size of erythema in the group of 23, 24 and 25 years old were significantly greater than that in the group of 20, 21 and 22 years olds. Similarly the latter was significantly greater than that in the group of 18 and 19 years olds. Furthermore, it was proven by the Kruskal-Wallis's method that the older a group was, the greater the chance of a large erythema. One explanation for this fact might be a decrease in the prevalence of tuberculosis infection in the younger generation as described above. Another explanation seems to be related to the revision of the Tuberculosis Prevention Law in 1974.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tuberculin skin testing in students of school of nursing]

Tuberculin skin testing in students of the School of Nursing Attached to National Hiroshima Hospital was analyzed. On initial test using 0.05 microgram of PPDs, diameter of erythema in 26.7% of 300 new students were less than 9 mm. Twelve of 24 who were tested by two-step method reacted more than 10 mm on the second test. Twenty-seven non-reactors who were vaccinated with BCG all reacted more than 10 mm after 9 to 16 weeks after vaccination. They might be vaccinated in the past by insufficient technique and better be revaccinated. Thirty-one of 49 students who graduated in 1998 were tested and their reactions were compared with those on entrance or after BCG vaccination. The two tests were spaced 31 to 34 months apart. The reactions were weakened in the cases after BCG vaccination, and in those who were not vaccinated on entrance, only a little booster effect were observed, except in 3 graduates whose reactions were significantly boosted and thought to be infected while in school. As there is considerable variation in tuberculin reactivity after BCG vaccination, diameter of reaction should be kept on personal health record as base line reaction to diagnose tuberculous infection henceforce.     

Tuberculin skin test conversion rate in dental health care workers-results of a prospective study.

OBJECTIVES: The tuberculin skin test conversion rate over 12 months in dentists, dental hygienists, and dental assistants was assessed in 3 US-Mexico border counties of Texas in which reported tuberculosis rates were high compared with the rates for Texas and the United States. METHODS: Tuberculin skin tests were administered to 284 subjects and repeated on nonreactors 12 months later. Participants also completed self-administered questionnaires. RESULTS: The baseline positive tuberculin skin test prevalence was 4. 6%. Nonreactors were more likely to have been born in the United States (P <.001). The tuberculin skin test conversion rate over 12 months was 1.7%. CONCLUSION: Results indicate a need for heightened awareness of tuberculosis transmission and annual surveillance by dental health care workers, as recommended by the Centers for Disease Control and Prevention.     

Tuberculin skin test reaction of health-care workers exposed to tuberculosis infection

OBJECTIVE: The objective of this study was to describe tuberculin skin test (TST) of health-care workers who had had contacts with a tuberculosis patient and to investigate whether the distributions of the size of TST were different by sputum-smear status of index cases and medical procedures done to the patient. SUBJECTS: Health-care workers who were exposed to tuberculosis infection through contact with patients before diagnosis of tuberculosis were included in this study. Index cases had pulmonary tuberculosis with positive sputum smear and were registered at Sapporo Public Health Office from April 2001 to March 2002. Subjects without past history of BCG (bacilli Calmette-Guerin) vaccinacion were excluded, and final study subjects were 415 (52 male and 363 female, mean age 29.1 years). METHOD: Characteristics of index cases and contact status were obtained from the registration cards of tuberculosis cases at Sapporo Public Health Office. Subjects were divided into two or more categories by the characteristics of index cases and the contact status. Distributions of TST of the subjects in different categories were compared. RESULTS: Contacts with patients received tracheal aspiration showed significantly larger TST reaction than contacts with patients not receiving tracheal aspiration. Among contacts with patients showing minimum to moderately positive sputum-smear, TST reaction was significantly larger in contacts with patients received tracheal aspiration (mean diameter of erythema 35.8 mm) than those not receiving tracheal aspiration (24.8 mm). In contrast, among contacts with patients of severely positive sputum-smear, TST reaction was not significantly different between contacts of patients received tracheal aspiration (35.3 mm) and not receiving tracheal aspiration (33.1 mm). CONCLUSION: TST was significantly stronger in contacts with a tuberculosis patient received tracheal aspiration, which indicates medical procedures such as tracheal aspiration increases the risk of tuberculosis infection in health-care workers.     

结核菌素皮肤试验硬结大小与发生结核病的危险：一项针对结核病接触者的大规模研究

资料来源：1990--2000年，加拿大不列颠哥伦比亚的8个省数据库中登记的结核病病人接触者。 目的：评价结核病病人接触者中的潜伏结核菌感染者在没有接受治疗的情况下，其结核菌素皮试（TST）硬结大小与其发展成为结核病的危险性。设计：随访12年的回顾性、大人群的队列研究。 结果：在26542例接触者中，180例发展成为结核病（结核病发病率为678／10万）。家庭接触者中TST硬结0～4mm者，结核病发病率为1014／10万，TST硬结5～9mm者，结核病发病率为2162／10万，TST硬结10～14mm者，结核病发病率为4478／10万。10岁以下儿童，TST硬结0～4mm者，结核病发病率为806／10万，TST硬结5～9mm者，结核病发病率为5556／10万，TST硬结10～14mm者，结核病发病率为42424／10万。免疫受到抑制的接触者中，TST硬结0～4mm者，结核病发病率为630／10万，TST硬结5～9mm者，结核病发病率为1923／10万，TST硬结10～14mm者，结核病发病率为1770／10万。 结论：家庭接触者、10岁以下儿童和免疫抑制的结核病病人接触者，无论TST硬结大小如何，其结核病发病率均较高。因此，这些接触者都可以从潜伏结核菌感染的治疗中获益，而不用考虑他们的TST硬结大小。     

Tuberculin skin test reactivity among adults infected with human immunodeficiency virus.

Infection with the human immunodeficiency virus type 1 (HIV-1) results in decreased cell-mediated immunity, which includes decreased delayed hypersensitivity to skin test antigens. HIV-1 seropositivity and skin test reactivity to purified protein derivative (PPD) were determined among 2042 healthy Haitian adults with normal chest radiographs. Among HIV-1-seropositive individuals, 52.3% (146/279) had PPD reactions greater than or equal to 10 mm compared with 67.2% (1184/1763) of the seronegative adults (P less than .001). However, the percentage of HIV-1-seropositive individuals with PPD reactions greater than or equal to 5 mm was similar to the percentage of seronegative adults with PPD reactions greater than or equal to 10 mm (180/279 [64.5%] vs. 1184/1763 [67.2%]). Assuming that the rate of prior infection with Mycobacterium tuberculosis was similar for HIV-1-seronegative and -seropositive populations, these data provide support for the recent recommendations to use induration of greater than or equal to 5 mm as evidence of past infection with M. tuberculosis in HIV-1 seropositive adults.     

Tuberculin skin test reactions by time of reading among Dutch travellers.

SETTING: Five travel and TB control clinics in The Netherlands. OBJECTIVE: To assess the variation of skin test reactions between different days of reading. DESIGN: Cohort study of non-BCG-vaccinated travellers. Mantoux skin test data were analysed for associations between time interval between administration and reading and reaction size. RESULTS: There were no significant differences in reaction size to 1 TU PPD between readings at day 3 or 4, either for pre-travel (n = 1004) or post-travel (n = 577) tests, before (P = 0.990 and 0.210, respectively) or after exclusion of 0 mm reactions (P = 0.330 and 0.474). Time intervals were not different for reaction sizes of 0, 1-9 or > or = 10 mm (P = 0.826 and 0.306). There were also no significant associations for simultaneous tests with a sensitin of Mycobacterium scrofulaceum. CONCLUSIONS: Tuberculin skin tests can be read on day 3 or 4, without compromising their validity.     

Tuberculin skin test size and risk of tuberculosis development: a large population-based study in contacts.

SETTING: Contacts of tuberculosis (TB) cases identified from eight Provincial databases in British Columbia, Canada, between 1990 and 2000. OBJECTIVE: To assess the risk of developing TB based on tuberculin skin test (TST) sizes in contacts of TB cases who did not receive treatment for latent TB infection. DESIGN: Retrospective, population-based cohort study with a 12-year follow-up. RESULTS: Among 26,542 contacts, 180 individuals developed TB (TB rate 678/100,000). Household contacts with a TST size 0-4 mm had a TB rate of 1014/100,000, those with 5-9 mm a TB rate of 2162/100,000 and those with 10-14 mm a rate of 4478/100,000. Children aged 0-10 years with 0-4 mm had a TB rate of 806/100,000, those with 5-9 mm a TB rate of 5556/100,000 and those with 10-14 mm a rate of 42,424/100,000. Immunosuppressed contacts with TST sizes 0-4 mm had a TB rate of 630/100,000, those with 5-9 mm a TB rate of 1923/100,000, and those with 10-14 mm a rate of 1770/100,000. CONCLUSIONS: TB rates were high for all TST sizes in household contacts, 0-10 year old contacts and immunosuppressed contacts. These contacts may benefit from treatment for latent TB infection, regardless of the size of their TST.     

泸州市石寨乡学龄儿童结核菌素试验结果分析

泸州市石寨乡位于江阳区，与自贡市富顺县、宜宾市江安县接壤，属农业乡，人口23000多人。2003年10月，市结防所与石寨乡卫生院技术人员，采用结核菌素试验(PPD)对在该乡石寨学校、久桥小学、凤龙小学就读的15岁以下儿童进行了结核杆菌感染状况的调查，报告如下。     

Tuberculin skin test reactivity is dependent on host genetic background in Colombian tuberculosis household contacts

The tuberculin skin test (TST) measures the intensity of antimycobacterial acquired immunity and is used to diagnose latent infection with Mycobacterium tuberculosis. We report evidence for a codominant gene explaining ～65% of the TST variability. Disregarding the host genetic background may lead to misclassifications of TST-based diagnosis of latent M. tuberculosis infection.     

Tuberculin skin test results in HIV-infected patients in India: implications for latent tuberculosis treatment.

OBJECTIVE: To evaluate the utility of the tuberculin skin test (TST) in detecting latent and active tuberculosis (TB) among human immunodeficiency virus (HIV) infected patients in South India. DESIGN: TSTs and CD4 counts were collected from 631 HIV-infected individuals without active TB and 209 antiretroviral and anti-tuberculosis treatment-na?ve HIV-infected patients with TB. We calculated the proportion of TST-positive individuals, as well as the sensitivity, specificity, positive predictive value (PPV) and negative predictive value of TST in the diagnosis of TB. RESULTS: Among subjects without active TB, 28% with a CD4 count <100 cells/microl vs. 43% of the total cohort had a TST >5 mm (P = 0.14), while the proportions with induration >10 mm were 14% vs. 36%, respectively (P < 0.01). Among those with active TB, using a 5 mm cut-off, the sensitivity was 42% for those with CD4 counts <200 cells/mul compared to 70% for those with CD4 counts >or=200 cells/microl (P < 0.001). The PPV for detecting active TB was 29%. CONCLUSIONS: TST is a poor predictor of both latent and active TB in HIV-infected individuals in TB endemic countries. Programmes offering treatment for latent TB should consider including all HIV-positive patients regardless of TST status, or use other indicators, such as CD4 count.