| Tuberculosis (TB) is the number one | | | | Rico, El Salvador, Nicaragua, Haiti, |
| infections disease killer worldwide. The | | | | Honduras, and areas undergoing civil war |
| World Health Care Organization estimates that | | | | (e.g. Balkan Countries). Countries in Eastern |
| 2 billion people have latent TB, while | | | | Europe have an intermediate prevalence. Costa |
| another 3 million people worldwide die each | | | | Rica, western and northern Europe, the United |
| year due to TB. On average, the isoniazid | | | | States, Canada, Israel, and most countries in |
| (INH) resistance rate is approximately 10% | | | | the Caribbean have the lowest prevalence. |
| and the rifampin resistance rate is | | | | Mortality / Morbidity: The case fatality rate |
| approximately 1%, with lower numbers in | | | | for TB was 50% for untreated patients before |
| countries with good TB programs and higher | | | | the advent of antibiotic therapy. Deaths |
| numbers in the countries with poor TB | | | | worldwide are are estimated at 3 million per |
| programs. Pathophysiology: Humans are the | | | | year. In United States, the mortality rate |
| only known reservoir for Mycobacterium | | | | dropped from 12.4 deaths per 100,000 |
| tuberculosis. TB is transmitted by airborne | | | | population (1953) to 0.6 deaths per 100,000 |
| droplet nuclei, which may contain fewer than | | | | population (1993); this is approximately 7% |
| 10 bacilli. Exposure to TB occurs by sharing | | | | per newly identified case. Multidrug |
| common airspace with a patient who is | | | | resistant during tuberculosis (MDR-TB) cases |
| infectious. When inhaled, droplet nuclei are | | | | have a higher reported mortality rate. |
| deposited within the terminal airspaces of | | | | Patients with underlying diseases |
| the lung. Upon encountering the bacilli, | | | | predisposing to active TB also have higher |
| macrophages ingest and transport the bacteria | | | | morality rates. Morality of untreated |
| to regional lymph nodes. The bacilli have 4 | | | | congenital TB is 50%. TB can mimic congenital |
| potential fates: 1. They may be killed by the | | | | syphilis or cytomegalovirus (CMV) infection. |
| immune system. 2. They may multiply and cause | | | | Race: Based on 1990 CDC data, case rates were |
| primary TB. 3. They may become dormant and | | | | 10 times higher for Asians and Pacific |
| remain asymptomatic, or 4. They may | | | | Islanders; 8 times higher for non Hispanic |
| proliferate after a latency period | | | | blacks; and 5 times higher for Hispanics, |
| (reactivation disease). Reactivation disease | | | | Native Americans, and Native Alaskans, as |
| may occur following either 2. or 3. above. | | | | compared to non Hispanic whites. However, |
| Frequency: In The US: Beginning in 1985, a | | | | race may not be an independent risk factor. |
| resurgence of TB was noted. The increase was | | | | Risk is best defined on the basis of social, |
| observed primarily in ethnic minorities and | | | | economic, and medical factors. Sex: Despite |
| especially in persons infected with HIV. TB | | | | the fact that TB rates have declined in both |
| control programs were revamped and | | | | sexes in the United States, certain |
| strengthened across the United States. After | | | | differences exist. TB rates in women decline |
| peaking at 25,287 (1993), the number of | | | | with age; in men, they increase with age. Men |
| reported cases began to fall again. In 2001, | | | | are more likely to have a positive tuberculin |
| 15,989 cases of TB were reported to the US | | | | skin test. The reason for these differences |
| Centers for Disease Control and Prevention | | | | may be social rather than biological in |
| (CDC). An estimated 10-15 million people have | | | | nature. Age: In the 1997 CDC data for the |
| latent infection. Among foreign immigrants, | | | | United States, more than 60% of cases |
| 74% of cases reported in 1998 were related to | | | | occurred in persons aged 25-64 years. The age |
| 7 countries: 1. Vietnam 2. Philippines 3. | | | | specific risk was highest in persons older |
| India 4. China 5. South Korea 6. Mexico 7. | | | | than 65 years. Infection in infants and young |
| Haiti Foreign born persons account for a | | | | children (up to 5years) always indicates |
| steadily increasing proportion of all | | | | recent transmission. If left untreated, it |
| reported TB cases. Internationally: An | | | | may result in life threatening meningitis or |
| estimated 20-33% of the world's population is | | | | disseminated disease, Elderly patients may |
| infected with M tuberculosis. Countries with | | | | not have typical signs and symptoms of |
| the highest prevalence include Russia, India, | | | | infection because they may not mount a good |
| Bangladesh, Pakistan, Pakistan, Indonesia, | | | | immune response. In elderly patients, an |
| Philippines, Vietnam, Korea, China, Tibet, | | | | active tuberculosis infection may present as |
| Hong Kong, Egypt, most Sub Saharan African | | | | an non resolving pneumonitis. |
| countries, Brazil, Mexico, Bolivia, Peru, | | | | |
| Colombia, Dominican Republic, Ecuador, Puerto | | | | More articles from this pro: D.S. |