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Cases = 150

Crude Rate per 100,00 population = 2.5

Race/Ethnicity-specific Rates per 100,000 population

Gender-specific Rates per 100,000 population

Tuberculosis (TB) is an airborne disease caused by Mycobacterium tuberculosis. General symptoms associated with TB are productive cough, coughing up blood, night sweats, fever, and malaise. TB usually affects the lungs, but can also affect other parts of the body such as the brain, kidneys, or spine. TB bacilli are put into the air when a person who has TB of the lungs or larynx coughs, sneezes, laughs, or sings. The bacilli are then inhaled by another person. Individuals who become infected from the inhaled TB bacilli are considered to have latent TB infection and cannot transmit the infection to others. Approximately 10% of the individuals who harbor the bacilli will progress from the stage of latent, or asymptomatic TB infection, to active disease. These individuals with active TB can transmit the disease to others. The majority of this report concerns cases of TB disease.

During 1999, 150 new cases (Figure 1) of tuberculosis were reported to the Indiana State Department of Health (ISDH). This represents a 20% decrease from the 188 cases reported in 1998. The state case rate was 2.5 cases per 100,000 population. The 1998 U.S. Bureau of the Census, inter-census estimates were used to calculate the rates reported in this document. TB was reported by 39 (42%) of the 92 counties. Generally, cases were associated with the urban and suburban counties.

With the advent of chemotherapy, TB is generally treated on an out-patient basis. Chemotherapy has led to a dramatic decline in the number of deaths due to TB disease. During 1994-1998, an average of 19 deaths was attributed to TB in the state of Indiana. The number of Hoosiers who have died from TB over the past several years, as shown in Figure 2, serves as a stark reminder that TB is still a deadly disease.

Figure 1.

In order for a person diagnosed with TB to be counted as a TB case, the medical record is reviewed by the local health official who is familiar with TB. If the medical history and clinical findings meet the predetermined case criteria, it is counted as a new TB case. The identification of Mycobacterium tuberculosis complex in a culture includes three species important in human disease: M. tuberculosis, M. bovis, and M. africanum. The case data in this report are compiled from the reports submitted through local health departments to ISDH. The cases are verified and categorized as confirmed, clinical, or provider diagnoses. Confirmed cases are those in which M. tuberculosis has been: 1) cultured from a clinical specimen OR has been demonstrated in a clinical specimen by a nucleic amplification (NAA) test, or 2) acid fast bacilli (AFB) are seen when a culture has not or cannot be obtained. A clinical case is one in which the individual has a positive tuberculin skin test, an abnormal chest x-ray, symptoms suggestive of TB disease, and has completed a medical evaluation. The third category is provider diagnosis. This category includes those cases where the physician has determined that the patient has TB, is treating him or her with an appropriate drug regimen, and the patient is showing clinical improvement. Many in this category include extra-pulmonary TB where laboratory confirmation may be lacking due to the site of the disease, and children in whom obtaining specimens is difficult and invasive procedures are not warranted. Figure 3 shows the percentage of reported TB cases by verification criteria.

As in years past, more males were diagnosed with TB than females (Figure 4). In 1999, males represented 63.0% of the newly diagnosed TB cases. The case rate per 100,000 population was 3.3 for males and 1.8 for females.

Case rates per 100,000 population by race and ethnicity were 1.7 for whites, 8.6 for blacks, 12.4 for Hispanics, and 25.0 for Asians. Although foreign-born persons had the greatest rates of TB, the number living in Indiana remains relatively small. For this reason, the rates in this group may be unstable.

In 1999, 24% (36/150) of cases were foreign-born, which means the country of origin was a country other than the U.S. (Figure 5). Among the foreign-born, Latin America accounted for 39% (14/36) of the cases. These individuals came from Mexico (11), Bolivia (1), Guatemala (1), and Trinidad and Tobago (1). South, east, and southeast Asia accounted for 33.3% (12/36) of the foreign-born cases with patients coming from Vietnam (3), the Philippines (3), China (1), Cambodia (1), Malaysia (1), and India (3). The Middle East represented another 8.3% (3/36) with patients from Pakistan (2) and Syria (1). Africa represented 11.1% (4/36), with patients from Zaire (1), South Africa (1), Sudan (1), and Ethiopia (1). The remaining 8.3% (3/36) came from Europe . These patients were from Bosnia (1), Italy (1), and Romania (1).

Figure 5.

In Indiana, the incidence of TB has been higher in older individuals (Figure 6). The case rate in this group has steadily declined. In 1999, 31.3% of the cases were over age 65 with a case rate of 6.2 per 100,000. Of the 150 cases reported, 25.3% were age 45-64 with a case rate of 3.3. The age group of 25-44 represented 27.3% of the cases for a case rate of 2.3, and 8.0% were age 15-24 for a case rate of 1.4. This year, 8.0% were under the age of 14 for a case rate of 1.0.

Figure 6.

Twelve children under the age of 15 were diagnosed in 1999 (Figure 7). Ten children were four years of age or younger. TB in young children is considered a sentinel event, representing failure to interrupt the transmission of TB, usually from an adult to a child.

Figure 7.

Several risk factors are associated with the development of TB disease or progression from infection to disease. The most important of these factors is HIV disease. In 1999, there were two individuals diagnosed with both TB and HIV (Figure 8) compared to the nine co-infected individuals in 1998. During 1999, HIV status was only known for approximately 10% of the cases. HIV status was unknown or the test was not offered in the great majority of the cases. Due to the small numbers of individuals diagnosed with both TB and HIV, significant variation in the numbers of cases identified can be expected to occur due to chance alone. National guidelines recommend HIV counseling and testing for all patients with TB.

Other risk factors associated with TB are alcohol use, homelessness, illicit drug use (injecting and non-injecting), residence in a long-term care (LTC) or correctional facility, or employment as a health care worker (HCW). The breakdown can be see in Table 1.

 Occupation is another variable used to detect trends. Compilation of these data show that 42.7% of the individuals diagnosed with TB disease were unemployed and 33.3% had known employment (Table 2). The unemployed category includes retired persons, children, and students. Five health care workers were diagnosed with disease in 1999.

Of the 150 cases reported in 1999, 79.3% (119/150) were pulmonary. Pulmonary cases are of particular concern since these individuals may actively transmit the disease to others. To break this cycle of transmission, appropriate and adequate therapy must be initiated and continued for the duration of the treatment period. ISDH follows the 1994 guidelines set by the American Thoracic Society and the Centers for Disease Control and Prevention (ATS/CDC). These guidelines recommend that at least three and preferably four drugs be used in the initial regimen. Figure 9 shows the impact of those guidelines on the prescribing practices of physicians before and after the new guidelines were adopted. In 1999, only 65% (98/150) of the cases initiated therapy on the preferred regimen containing isoniazid, rifampin, and pyrazinamide, with either ethambutol or streptomycin included until drug susceptibility results are available. The percentage of patients who were started on at least isoniazid, rifampin, and pyrazinamide was 86% (129/150). Three patients were not started on chemotherapy because they were dead at the time of diagnosis. A post-mortem diagnosis of TB suggests that there were either delays in the patient seeking treatment or in the diagnosis of TB. Disease transmission may have occurred before anyone suspected TB. Contact investigations based on the late diagnosis are crucial to protect the survivors.

Drug susceptibility testing is recommended for all positive TB cultures to detect any resistance to the medications prescribed. Of the 150 TB cases reported, 3.3% (5/150) had resistance to at least one anti-tuberculous drug. In 1999, susceptibility testing was performed on only 68.6% (48/70) of initial positive cultures. Drug susceptibility testing is automatically done on all initial positive cultures submitted to the State TB Laboratory. Private laboratories do not routinely perform them unless requested. Multi-drug resistant (MDR) TB is defined as resistance to both isoniazid and rifampin. MDR-TB is of particular public health concern since these two drugs are the most effective medications used to treat TB. If the organism develops resistance to these two medications, they no longer will be effective to treat this disease, thus limiting the arsenal of drugs shown to be effective in the treatment and management of TB. There was one case of MDR-TB in 1999.

INH-resistant TB is treatable and curable with the standard four-drug regimen. Close and careful monitoring of these patients is necessary to prevent additional drug resistance. Drug resistance was documented in Hendricks County (isoniazid), Steuben County (isoniazid), Vanderburgh County (isoniazid and streptomycin), and Allen County (isoniazid and rifampin). If resistance to rifampin or pyrazinamide is present, the length of treatment must be prolonged. The number of drug resistant cases since 1994 is shown in Figure 10.

Besides drug resistance, inadequate response to therapy and non-compliance are major reasons for having to extend the treatment period. Patients whose cultures have not become negative or whose symptoms have not improved after two months of therapy should be re-evaluated for drug resistance, as well as failing to adhere to the treatment regimen. The proportion of patients who convert their sputum cultures to negative within 90 days is shown in Figure 11. The most effective method to assure that the patient is complying with the prescribed regimen is to use directly observed therapy (DOT). DOT is a strategy proven to ensure completion of therapy, thereby preventing the emergence of acquired drug resistance. DOT is the standard of care in Indiana to ensure compliance with and completion of therapy and should be considered for all TB patients. Every effort must be made to initiate DOT when the patient is first started on anti-TB medications, especially pulmonary and drug resistant cases. During 1999, 69.0% (101/147 alive at time of diagnosis) of all cases were on DOT for at least some portion of the treatment period (Figure 12).

The top priority of TB control and prevention efforts is to ensure completion of therapy for TB patients. Indiana’s objective is to have at least 90% of all patients complete an adequate and appropriate course of therapy. The completion of therapy index is calculated for groups of cases by dividing the number of cases who complete therapy within one year by the total number of cases who are expected to complete therapy within the designated time period. Exclusions are deducted from the denominator and are not included in the rate calculations. Exclusions from the rate calculations are those cases reported at the time of death, patients who were never started on therapy, and patients who died before completing therapy. Therapy is considered to be incomplete for those patients who were reported as moved, uncooperative or refused, or disposition unknown.

In previous years, the statistics for Marion County had been reported separately from the rest of the state. Due to changes in how the CDC calculates completion rates, the two entities will be reported in combined figures. This combination of reporting areas is consistent throughout the nation so that states can compare the data.

Because completion data are gathered at the end of therapy, the current data are for those patients who initiated therapy in 1998. The completion rate for that year was 94%, as shown in Figure 13.

Figure 13.

The second priority in TB control and prevention is to identify those individuals who are infected with TB and could benefit the most from preventive therapy. Persons in the following categories are at high risk for developing active disease once infected and should receive preventive therapy regardless of their age: 1) close contacts to a case of active pulmonary or laryngeal TB; 2) individuals who have converted their skin test from negative to positive within the last two years; 3) injection drug users; 4) persons known or suspected of having HIV infection; 5) persons with certain medical conditions; and 6) persons with a chest x-ray suggestive of previous TB who received inadequate treatment.

The best means of identifying exposed and infected individuals is to perform a complete and thorough contact investigation. During 1999, 124 pulmonary cases were diagnosed. Some investigations for cases reported late in the year are incomplete at this time. Because a contact investigation can take three months or longer, completed contact identification information is available only for the 147 pulmonary TB cases reported in 1998.

Based on the available information reported to the State, eight contacts were found to have active TB disease and were identified as a result of the contact investigation. Based on national estimates, each infectious case averages nine contacts, 21% of whom became infected, and 1% were found to have disease when identified as a contact. Of the contacts examined during 1998, 8.8% were diagnosed with TB infection. Of those individuals, 39.0% were started on preventive therapy. Children under the age of 15 represented 2.0% of the infected contacts and 100.0% were started on preventive therapy.

Rates for the completion of preventive therapy for contacts are tracked by age. The completion of preventive therapy is calculated much the same as completion of curative therapy. The number of patients who are reported as having completed a course of preventive therapy is divided into the number of patients who are expected to complete therapy. The exclusions are those who develop active disease, die before therapy is completed, discontinue therapy due to adverse reactions, or if the individual moved out of the jurisdiction.

In the past, completion rates for preventive therapy were calculated in six-month increments, i.e., the first and second half of each year. The rates in the charts on the next page have been recalculated to reflect data for the State as a whole for complete calendar years. During 1998, the state’s completion rate for contacts under the age of 15 was 56.3% (Figure 14). For those aged 15 and older, the completion rate was 80.0% (Figure 15).

Figure 16 gives an overview of where the TB cases occurred within the state. The numbers represent the number of cases in each county, with the number of drug resistant cases in the dark circle. TB was reported by 39 of the 92 (42%) Indiana counties. Five drug resistant cases were reported in four different counties.

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