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