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