Tuberculosis1.
Identification-identification requires finding the organismMycobacterium tuberculosis, the cause of TB. Respiratory symptomsshould prompt an exam of the sputum, first by an acid-fast smear, then byculture and identification of the organism. The smear results should beavailable in hours. If positive, a diagnosis of TB should be assumed andtreatment started. Final confirmation requires isolation of the culture.
Radiographs of the chest are helpful in the identification. 2. Agent-TB is caused by an infectious agent known as mycobacteriumtuberculosis. 3. Occurrence-The number of TB cases had been declining by anaverage of 5% per year nationally since 1953.
This situation changed in1985, when the incidence began to climb. In 1990, 25,701 TB cases werereported to the CDC. This represented a 9. 4% increase over 1989 andwas the largest for a single year since 1953.
Reported cases increased15. 89% between 1985 and 1990. Although the AIDS epidemic has caused many of the changes,immigration, homelessness, drug abuse prison overcrowding, acts inpublic health funding, and drug resistance have also contributed to asituation that is out of control in some parts of the country. And becauseTB is contagious, the risk extends beyond the groups traditionallyconsidered high risk. TB has changed from a disease of older people to one of young adultsand children. It has also evolved from a disease that struck across allracial and ethnic lines to one that is far more common among black andLatino populations than whites.
The age distribution of new cases alsopoint to a strong-but not absolute-link with AIDS. The greatest increasehas been in people 24-44, the same group most seriously affected by HIVinfection. 4. Reservoir-Only people were discussed but also animals. 5. Mode of Transmission-The agent infects the lungs by inhalation ofinfected droplets formed during coughing, singing or sneezing of anindividual with the active form of the disease.
6. Incubation period-about 4-12 weeks7. Period of communicability-As long as viable tubercle bacilli are beingdischarged in the sputum. 8.
Susceptibility-The most hazardous period for development of clinicaldisease is the first 6-12 months after infection. But in the case of HIVinfection, infection and development of TB symptoms is shorter thanthat in HIV negative patients with TB. According to some reports, HIVinfected patients can develop primary progressive TB within a few weeksof exposure to M. tuberculosis.
9. Resistance-TB has changed bacteriologically. Today in New York, asmany as 20% of TB patients are infected with M. tuberculosis that isresistant to isoniazid (INH) and rifampin.
TB experts believe that the drugresistance problem is due in part to poor compliance, which is bad amongTB patients. In addition, widespread indifference to TB during the last twodecades meant that no new specific anti-TB drugs entered the pipeline,monitoring for resistance lagged, and rapid diagnostic tests were notdeveloped. 10. Methods of control-Controlling TB is very difficult. A.
Preventive measures-TB specialist overwhelmingly prefer theintradermal Mantoux test for screening. Candidates for screening includeHlV-positive patients, close contacts of TB patients, people from countrieswith high TB rates or medical conditions that predispose to active TB, andresidents of long-term-care facilities. Because of the high prevalence ofanergy among HlV-infected patients, the CDC recommends administeringcompanion tests for delayed-type hypersensitivity simultaneously with theMantoux test. Most TB patients are treated with INH and rifampin as outpatients for 6to 9 months. Much of the responsibility for detection, prevention andtreatment lies with our increasingly impacted and understaffed publichealth clinics throughout the country.
The private sector also shares in anincreasing demand for treatment of cases. More than 35% of the reportedcases reported to the county health department come from sources otherthan public health facilities. Preventive therapy ordinarily consist of INH 300 mgs. daily for 6 to 12months. Where the risk of TB is very high, such as in those who are HlV-positive, 12 months is recommended.
In all cases it is essential to rule outactive TB before giving INH alone. The BCG (Bacillus of Calmette and Guerin) vaccine has been used inmany parts of the world to prevent TB. Unless the BCG vaccine has beenreceived within the past year, a positive TB skin test result in any personshould be considered as indicating TB infection regardless of the remotehistory of a BCG vaccination. They should be assessed regarding TBdisease. B.
Control of patients, contacts and the immediate environment-Ofparticular concern is the documented increase of disease in children. When TB is under control in a community, children should rarely beinfected and essentially have no disease because they get the diseaseonly from undetected adult cases. This indicates that adults withundetected TB are transmitting it to children. Another reason TB has remained endemic is because of the dramaticincrease in the population and the changing demographics. Immigration oflarge numbers of persons from countries where TB is common hasresulted in sustained numbers of new TB cases, despite the generaldecline in those born in the U. S.
ReferencesBenenson, A. S. , (1990). Control of communicable disease in man (15thed. ).
Washington D. C. : American Public Health Association. Davidson, P. T.
, Diferdinanando, G. T. , Reichman, L. B.
, Snider,D. E. (May15,1992). TB: coming soon to your town? Patient Care.
