[The natural history of tuberculosis infection and skin tuberculin reaction]. / Histoire naturelle de l'infection tuberculeuse et réaction cutanée tuberculinique.

Though most often asymptomatic, tuberculous infection induces a delayed hypersensitivity reaction in the host by activating cellular immunity thus rendering the host refractory, "a priori", to a new infection; at least provided that the infecting dose is not massive or that the immune system of the host is not compromised. Less that ten per cent of immuno-competent individuals infected by Mycobacterium tuberculosis will develop tuberculous disease during their life. The intradermal reaction (IDR to tuberculin) in revealing delayed hypersensitivity to Mycobacterial antigens is in the absence of obvious signs, the only means of diagnosing a tuberculous infection in an individual. It is performed in France by an intradermal injection of 0.1 mls (10 U) of Merieux tuberculin. The response is read at 72 hours. In those who have not had BCG vaccination, an area of induration with a diameter of greater than or equal to 10 mm gives a positive result and is evidence of a tuberculous infection. The test is negative if the diameter is less than 5 mm and indeterminate between 5 and 9 mm. These indeterminate reactions may be the consequence of previous BCG vaccination or of a contact with atypical Mycobacteria in the environment. An IDR of greater than or equal to 10 mm less than ten years after BCG vaccination would not permit any discrimination between a reaction to the vaccine or an authentic tuberculous infection. On the other hand, an IDR of greater than 10 mm ten years after BCG vaccination is evidence of renewed contact with wild tubercle bacilli in 88 per cent of cases. In individuals whose immune defence is altered in particular in patients infected with HIV the threshold of positivity for IDR is lowered to 5 mm.

Pautas para el estudio de contactos de tuberculosis (Test de Combe)

La tuberculosis es un gran problema de salud pública; presenta una alta incidencia a nivel mundial y en nuestro país esta incidencia tiene una gran magnitud, pero existe un importante subregistro. Hay cuatro criterios clásicos para hacer el estudio de Contacto de pacientes tuberculosos (test de Combe): epidemiológico, clínico, tuberculínico y radiológico. En la presente publicación se revisarán los criterios que en pediatría son de importancia en el estudio de contactos. Si el análisis de estos criterios sugiere la posibilidad de un caso de enfermedad tuberculosa, podemos hacer un mejor estudio con ayudas diagnósticas como aislamiento del bacilo, biopsia, serodiagnóstico y otros exámenes de mayor tecnología.

An attempt to predict anergy in tuberculosis suspect cynomolgus monkeys.

Acid-fast microorganisms were identified from the tuberculous lesions of a male cynomolgus monkey (Macaca fascicularis). Twenty-two other cynomolgus monkeys housed in the same room were presumed exposed to tuberculosis (Mycobacterium spp.). In addition to standard intradermal (ID) tuberculin testing, clinicians attempted to evaluate the immune status of these monkeys in order to identify animals exhibiting false negative (anergy) ID tuberculin tests. Twenty-one of the potentially exposed monkeys were immunized with tetanus toxoid (TT). Tetanus antitoxin (TAT) titers were measured before and after immunization. The delayed cutaneous hypersensitivity (DCH) reaction to TT was evaluated using a commercially available human test panel. Some animals did not exhibit a DCH reaction to TT. At necropsy 1 of the 21 animals exhibited tuberculous lesions, and acid-fast microorganisms were identified on direct smears of lymphatic tissue of a second animal. Although reported to be of value in assessing the cellular immune status of rhesus monkeys (Macaca mulatta), the delayed cutaneous hypersensitivity response to tetanus toxoid was not helpful during this outbreak in identifying cynomolgus monkeys infected with M. tuberculosis, or in interpreting suspect ID tuberculin tests.

Probabilidades de classificação errada ao teste tuberculinico segundo critério em vigor; suas implicaçõws em programas de luta antituberculosa

Os autores se propõem a estimar as probabilidades de classificação errada nos resultados do teste tuberculinico,em diferentes grupos etários.Analisam 35.680 resultados de testes tuberculinicos efetuados na população que demandou o Centro de Saúde Polivalente de Ribeirão Preto,SP,durante 12meses consecutivos, a partir de maio de 1973,seguindo uma metodolgia estatistica denominada"critério de melhores regiões possivéis de classificação".Apresentam as etapas do estudo,mostrando as probabilidades de classificaçãoerrônea dos tipos de reatorese suas implicações de acordo com a finalidade do uso do testetuberculinico,assim como as implicações operacionais.Concluem que,embora seja possivél demarcar regiões de classificação dos resultados do teste,mais corretas do ponto de vista estatístico,suas implicações operacionais não aconselham seu uso na rotina de saúde pública

Lepromin and tuberculin tests in Venezuelan leprosy foci, induction of lepromin reactivity by BCG vaccination

The reactions to tuberculin and lepromin were studied in 8,353 inhabitants of leprosy foci in rural areas in Venezuela. Of this general group, a total of 1,356 (16.2 per cent) proved to be negative to the Mitsuda, test, while 5,205 (62.5 per cent) were Mantoux negative, In the group of Mitsuda-positive persons 44.8 per cent were also Mantoux positive, while in the Mitsuda-negative group only 3 per cent were Mantoux positive. In the Mantoux-positive group 99.5 per cent were Mitsuda-positive, while in the Mantoux-negative group 74.4 per cent were Mitsuda-positive. Considering that 16.2 per cent of the persons examined were found to be without protection against leprosy in the first tests, and taking into account that almost all lepromatous and indeterminate cases come from the lepromin negatives, which form the endemic matrix of the disease, there can be no doubt but that BCG vaccination will be an effective prophylaxis, at least in rural areas, when it can reduce the percentage of Mitsuda negative from 16.2 to 1.3 per cent.