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.

[The role of health care providers in the late diagnosis of pulmonary tuberculosis among adults in Medellín, Colombia]. / Papel del personal de salud en el diagnóstico tardío de la tuberculosis pulmonar en adultos de Medellín, Colombia.

OBJECTIVE: To describe the role of health care providers in the delayed diagnosis of pulmonary tuberculosis (PTB) among the adult population in a city in Colombia. METHODS: A case study of PTB diagnosis among adults in the city of Medellín, Colombia, in 2007. Quantitative and qualitative data were collected through in-depth interviews with 19 patients (11 with early diagnosis and 8 with late diagnosis), from medical records, and by a survey of PTB-related knowledge and practices among 89 doctors and nurses at health care clinics. A research workshop was held with patients to share the results and validate new categories. RESULTS: A lack of PTB knowledge and patient stereotyping were found to lead to misinterpretation of symptoms and the use of symptomatic treatments. The lack of knowledge regarding risk factors and clinical protocols made diagnosis difficult when the patient did not match the stereotype or presented with a more well-known illness. Misinformation on PTB transmission and inappropriate measures led to discriminatory practices and social isolation and only reinforced stereotypes and stigma, which in turn discouraged the quest for medical attention. CONCLUSIONS: Health care providers played a large part in the late diagnosis of PTB in the adults studied. Beliefs regarding social stigma and a lack of knowledge about the disease-shared by providers and patients-contributed to stereotyping of the illness and the disease-carrier, and limited the probability of an early diagnosis of PTB.

Papel del personal de salud en el diagnóstico tardío de la tuberculosis pulmonar en adultos de Medellín, Colombia / The role of health care providers in the late diagnosis of pulmonary tuberculosis among adults in Medellín, Colombia

Objetivo: Describir el papel que desempeña el personal de salud (PS) en el retraso del diagnóstico de la tuberculosis pulmonar (TBP) en la población adulta de una ciudad colombiana. Métodos: Estudio de caso sobre el diagnóstico de la TBP en adultos de la ciudad de Medellín, Colombia, en 2007. Se recogieron datos cuantitativos y cualitativos mediante entrevistas en profundidad a 19 pacientes (11 con diagnóstico oportuno y 8 con diagnóstico tardío), la revisión de sus historias clínicas y encuestas sobre los conocimientos y las prácticas relacionadas con la TBP a 89 médicos y enfermeros de 12 instituciones prestadoras de servicios de salud. Se realizó un taller investigativo con los pacientes a fin de socializar los resultados y validar las categorías emergentes. Resultados: Se observó un escaso conocimiento sobre la TBP y una imagen estereotipada de los pacientes que llevan a malinterpretar los síntomas y emplear tratamientos sintomáticos. Los insuficientes conocimientos del PS sobre los factores de riesgo y el cuadro clínico dificultaron el diagnóstico cuando el paciente no reflejaba el estereotipo o presentaba una enfermedad ya conocida. La desinformación sobre la transmisión de la TBP y la prescripción incorrecta de medidas de aislamiento propiciaron prácticas discriminatorias y aislamiento social y reforzaron los estereotipos y la estigmatización, lo que también limitó la búsqueda de ayuda médica. Conclusiones: El PS desempeñó un papel fundamental en el diagnóstico tardío de la TBP en los adultos estudiados. Las creencias asociadas con el estigma social y el insuficiente conocimiento sobre la enfermedad -compartidos por el PS y los pacientes- contribuyen a la construcción social del estereotipo de la enfermedad y el enfermo y reducen las posibilidades de llegar a un diagnóstico oportuno de la TBP.

Objective: To describe the role of health care providers in the delayed diagnosis of pulmonary tuberculosis (PTB) among the adult population in a city in Colombia. Methods: A case study of PTB diagnosis among adults in the city of Medellín, Colombia, in 2007. Quantitative and qualitative data were collected through in-depth interviews with 19 patients (11 with early diagnosis and 8 with late diagnosis), from medical records, and by a survey of PTB-related knowledge and practices among 89 doctors and nurses at health care clinics. A research workshop was held with patients to share the results and validate new categories. Results: A lack of PTB knowledge and patient stereotyping were found to lead to misinterpretation of symptoms and the use of symptomatic treatments. The lack of knowledge regarding risk factors and clinical protocols made diagnosis difficult when the patient did not match the stereotype or presented with a more well-known illness. Misinformation on PTB transmission and inappropriate measures led to discriminatory practices and social isolation and only reinforced stereotypes and stigma, which in turn discouraged the quest for medical attention. Conclusions: Health care providers played a large part in the late diagnosis of PTB in the adults studied. Beliefs regarding social stigma and a lack of knowledge about the disease-shared by providers and patients-contributed to stereotyping of the illness and the disease-carrier, and limited the probability of an early diagnosis of PTB.

IFNgamma response to Mycobacterium tuberculosis, risk of infection and disease in household contacts of tuberculosis patients in Colombia.

OBJECTIVES: Household contacts (HHCs) of pulmonary tuberculosis patients are at high risk of Mycobacterium tuberculosis infection and early disease development. Identification of individuals at risk of tuberculosis disease is a desirable goal for tuberculosis control. Interferon-gamma release assays (IGRAs) using specific M. tuberculosis antigens provide an alternative to tuberculin skin testing (TST) for infection detection. Additionally, the levels of IFNgamma produced in response to these antigens may have prognostic value. We estimated the prevalence of M. tuberculosis infection by IGRA and TST in HHCs and their source population (SP), and assessed whether IFNgamma levels in HHCs correlate with tuberculosis development. METHODS: A cohort of 2060 HHCs was followed for 2-3 years after exposure to a tuberculosis case. Besides TST, IFNgamma responses to mycobacterial antigens: CFP, CFP-10, HspX and Ag85A were assessed in 7-days whole blood cultures and compared to 766 individuals from the SP in Medellín, Colombia. Isoniazid prophylaxis was not offered to child contacts because Colombian tuberculosis regulations consider it only in children under 5 years, TST positive without BCG vaccination. RESULTS: Using TST 65.9% of HHCs and 42.7% subjects from the SP were positive (OR 2.60, p<0.0001). IFNgamma response to CFP-10, a biomarker of M. tuberculosis infection, tested positive in 66.3% HHCs and 24.3% from the SP (OR = 6.07, p<0.0001). Tuberculosis incidence rate was 7.0/1000 person years. Children <5 years accounted for 21.6% of incident cases. No significant difference was found between positive and negative IFNgamma responders to CFP-10 (HR 1.82 95% CI 0.79-4.20 p = 0.16). However, a significant trend for tuberculosis development amongst high HHC IFNgamma producers was observed (trend Log rank p = 0.007). DISCUSSION: CFP-10-induced IFNgamma production is useful to establish tuberculosis infection prevalence amongst HHC and identify those at highest risk of disease. The high tuberculosis incidence amongst children supports administration of chemoprophylaxis to child contacts regardless of BCG vaccination.