Tuberculin Skin Testing in US Navy and Marine Corps Personnel and Recruits, 1980-86 ELEANOR R. CROSS, MS,
AND
KENNETH C. HYAMS, MD
Abstract: An extensive skin testing program is part of the United States Naval Medical Command's infectious disease control effort. From 1980 to 1986, 2,306,533 skin tests, using five TU PPD, were performed on active-duty Navy and Marine Corps personnel, 0.97 percent of which were positive. A downward trend in positive tests was found with a high of 1.43 percent in 1980 and a low of0.80 percent in 1983. Since 1984, the percentage of positive tests has remained the same or increased. Shore-based medical facilities around the world reported 1,491,646 skin tests with 1.07 percent positive; Navy ships reported 814,887 skin tests with 0.78 percent positive. PPD-positivity
for ships in the Pacific area was higher (0.98 percent) than for ships in the Atlantic (0.62 percent). During this same period, the percentage of positive tests in Navy and Marine Corps recruits ranged from a high of 1.82 percent in 1981 to a low of 1.23 percent in 1986. Since 1984, the percentage of positive tests has remained relatively stable in recruits. The frequency of positive PPD tests found in this study is lower than the percentage positive (1.59 percent) found in active-duty Navy personnel in 1969 and the percentage positive (5.2 percent) found in a study of Navy and Marine Corps recruits between 1958 and 1969. (Am J Public Health 1990; 80:435-438.)
Introduction Since the early 1800s, the Medical Department of the US Navy has recognized the high transmission potential of tuberculosis. 1 Not only is there an increase in risk of exposure from world-wide travel but, as epidemiological studies have demonstrated, environmental conditions aboard ships are ideal for transmission.2-4 Early attempts at TB control included screening sailors prior to an extended cruise and rejecting "all persons who were believed to be of unsound constitution."' Today, the Navy's tuberculosis control program includes tuberculin skin test screening, contact investigation, and treatment of active cases and selected skin test reactors.5 The Naval Medical Command directs all personnel whose previous test was negative to be periodically skin tested by the Mantoux method using 5 tuberculin units (TU) Purified Protein Derivative (PPD).5 Annual screening is done on individuals assigned to operational units and to areas where possible exposure to tuberculosis is high, i.e., members of deployable Navy and Marine Corps units, shipboard personnel, and health care personnel. Sailors in low-risk areas, such as shore-based personnel in the United States, are tested every three years. A person with induration measuring 10 mm or greater 48 to 72 hours after the administration of a 5 TU skin test is considered a "tuberculin reactor."5 A new reactor is defined as "a person who has become a reactor within the past three years," and persons who are found to be reactors for the first time but whose prior tuberculin status is unknown. Since earlier studies indicated that a new reactor rate of 1 to 2 percent of personnel tested could be expected in many Navy and Marine Corps settings, the Naval Medical Command recommends a search for active cases of tuberculosis when the rate of new reactors exceeds 2.5 percent in groups of approximately 100 or more personnel.5 This report examines tuberculosis skin testing in the Navy from 1980 to 1986. Comparisons are made over time in and recruits Navy and Marine Corps active-duty personnel stationed in various geographic locations.
Methods Each month, all outpatient facilities ofthe Naval Medical Command report the number of PPD tests performed and the number of reactors. Information on age, sex, race, and the exact size of the reaction is not recorded, however. In this study, computerized files of skin test results for the period January 1980 to December 1986 were analyzed. Reports are received each month from approximately 600 shore-based facilities and from over 500 ships. Approximately 25 percent of the shore-based facilities are located outside of the United States. It is important to note that the location of the reporting facility may not necessarily be the location of the tuberculosis contact. Data from shore-based facilities may include skin test results on individuals from ships during port visits as well as results on individuals transferred to a facility from a different location. Although these tests are administered and read by a number of different medical personnel, the Naval Medical Command provides very specific instructions on the administration and reading of these tests.5 Therefore, the overall results of the skin tests from different locations are generally comparable. Tubersol (Connaught, Inc., Swiftwater, PA) was used for the skin testing during the period of this study. For the 1980 to 1986 study period, the total number of skin tests performed in active-duty personnel fluctuated from a high of 373,747 in 1983 to a low of 287,251 in 1986. Average annual active-duty strength increased from 720,832 in 1980 to 805,128 in 1986. Consequently, approximately 40-50 percent of the total force was tested annually. The mean age of active-duty personnel increased from age 25.0 years in 1980 to age 26.1 years in 1986. The mean sex ratio of Navy and Marine Corps personnel changed from 16:1 (male:female) in 1980 to 11:1 in 1986. For recruit personnel, approximately 83 percent were between the ages 17 to 21 years during the study period. The percentage of both Black and Hispanic recruits increased during the period 1981 to 1986 from 12 percent to 17 percent for Blacks and from 4 percent to 9 percent for Hispanics.
Address reprint requests to Eleanor R. Cross, Associate Investigator, Division of Epidemiology, Department of Infectious Diseases, Naval Medical Research Institute, 12300 Washington Avenue, Rockville, MD 20852. Dr. Hyams is Head of the Division of Epidemiology at NMRI. This paper, submitted to the Journal April 4, 1989, was revised and accepted for publication September 20, 1989.
Results Between 1980 and 1986, a total of 2,306,533 tests were read for all active-duty Navy and Marine Corps personnel, 0.97 percent of which were positive. The rate of positive tests decreased from a high of 1.43 percent in 1980 to a low of 0.80
AJPH April 1990, Vol. 80, No. 4
435
CROSS AND HYAMS 2.00
percent in 1983. In 1983, this downward trend changed, and from 1984 to 1986 the percentage of positive tests either remained the same or increased (Table 1, Figure 1).
81
Shore-based Facilities
x
In shore-based facilities located inside of the continental United States (CONUS), a total of 1,319,610 tuberculin skin tests were read, of which 1.00 percent were positive. The percentage of positive tests dropped from a high of 1.41 percent in 1980 to a low of 0.83 percent in 1983. After 1983, the rate of positive tests either rose or remained the same (Figure 2). The average percentage of positive tests in shore-based facilities located outside the continental United States (OCONUS) was higher (1.61 percent) but followed a very similar trend (Figure 2). By location of shore-based facilities, the highest frequency of positive tests was in the Philippines (3.10 percent), followed by Japan (2.90 percent), Korea (2.00 percent), Guam (1.88 percent), Bahrain (1.66 percent), and Okinawa (1.40 percent). By US Naval District, skin test positivity was highest in the Northwestern United States (1.79 percent) and Northern California (1.77 percent) (Table 1, Figure 3). The lowest rates were found in the North Central area (0.46 percent). Positive TB Skin Tests Aboard Ships Of 814,887 skin tests read aboard ships, 0.78 percent were positive. The positive rate was higher in ships based in the Pacific area (0.98 percent) than for ships based in the Atlantic (0.62 percent). As in shore-based facilities, there was a general downward trend in both areas from 1980 to 1982, especially in the Pacific. After 1982, the rates of positive tests remained fairly stable (Table 1, Figure 4).
a
-1
11i50
1
s.-II-
I ,
(IC
\
Shore-based Total Stipboard
0.50
-
0.00
-
z
1981
1980
1 983
1982
1984
1985
1986
FIGURE 1-Frequency of Positive Tuberculin Tests in all Active-duty US Naval and Marine Corps Personnel, in all Shore-based Naval Medical Facilities, and in all ships, 1980-86
of recruits with a positive PPD skin test has remained relatively stable at between 1.28 and 1.23 percent. Discussion
The results of this study show a downward trend in the frequency of positive TB skin tests from 1980 to 1983. After 1983, the percentage of positive tests either remained stable or increased. It is noteworthy that these general trends occurred in all population groups of active-duty US Navy and Marine Corps personnel. The reason why different populations tested in different areas of the world exhibited such closely similar patterns of positive tests could not be determined. The data indicate, however, that the threat of TB infection is greatest in the Pacific for both shore-based and shipboard military personnel.
Navy and Marine Corps Recruits
Between 1980 and 1986, a total of 618,074 skin tests were performed on recruits, 1.45 percent of which were positive (Table 1, Figure 5). The highest percentage of positive tests (1.82 percent) was found in 1981. Since 1984, the percentage
TABLE 1-Percent Positive Tuberculin Reactors In Active-duty US Navy and Marine Corps Personnel and In Recruits, 1980-86 Number Reactors/Number Read x 100 R Read Location
Average 1980-86
1980
1981
1982
0.87
211232
1.151939 168485
0.83 2296 1860
2068 1.00 206074
1402 o.78 179945
1.06 149433 1578
1.26 24231-
11825182
23 1.53 27643
1.42 31287-
1.89-31905
1.07 16020
1 52
1.25
CONUS
1.00 1319610 13248
1.41 167518 236
1.18 199209 2355
1622 0.84 193872
OCONUS
1.61
-5 2.26 24140
1.93 2051
1491646
17203
290
191658
2750
219710
1986
2491 1.07 233717
1 16 318616 -368
Shore-based
1985
27 0.82 340588
1.43 305937 4385
Total
1984 0.92 356926 28
0.97 2306533 228
Total
1983
0.812604 323468 088
1927
218103
2978 0.80 373747
087
2158
248741
1847
0.92 287251 264
Atlantic
420 0.91 4839
1.33 6699
0.97 5245 52
47 0.89 5274
0.80 55244
1.26 7791 -79
0.4621... 11069
0.83 40 479
Pacific
1.87 125640 235
2.61 17442 44-2
2.25 15256 344
21.36 18957
1.2929545 19656
1.64 19852 32
1.95-021 20218
2.25 14259 32
0.78 814887 638
1477 1.29 114279
939 0.95 98906
677 0.64 105365
0.66 125006 820
-792 0.64 123209
0.72 129356 937
0.59 70118798
Atlantic
2-2 0.62 454836
478 0.83 57459
0.77 54535-
0.53 57699-
0.52 73617-
0.60 69837 e9293
71 0.66 71881
0.46 69606
Pacific
0.98 360051 380-
1.76 56820-
-181.17 44371
0.78 47666-
0.85 51389-
0.70 53372-
0.81 57475
0.78 48958-
Recruits
-m 1.45618074
1.76-13 84824
1.8292689 -"
1.3197283 -'
1.57 95853 '506
1.28.22363 106640
1.2787262 -'
-"0 1.2373723
Shipboard Total
436
AJPH April 1990, Vol. 80, No. 4
TUBERCULIN SKIN TESTING IN NAVY PERSONNEL 3 00 -
8
8
x
x
a
a
LU
2
AND
KENNETH C. HYAMS, MD
Abstract: An extensive skin testing program is part of the United States Naval Medical Command's infectious disease control effort. From 1980 to 1986, 2,306,533 skin tests, using five TU PPD, were performed on active-duty Navy and Marine Corps personnel, 0.97 percent of which were positive. A downward trend in positive tests was found with a high of 1.43 percent in 1980 and a low of0.80 percent in 1983. Since 1984, the percentage of positive tests has remained the same or increased. Shore-based medical facilities around the world reported 1,491,646 skin tests with 1.07 percent positive; Navy ships reported 814,887 skin tests with 0.78 percent positive. PPD-positivity
for ships in the Pacific area was higher (0.98 percent) than for ships in the Atlantic (0.62 percent). During this same period, the percentage of positive tests in Navy and Marine Corps recruits ranged from a high of 1.82 percent in 1981 to a low of 1.23 percent in 1986. Since 1984, the percentage of positive tests has remained relatively stable in recruits. The frequency of positive PPD tests found in this study is lower than the percentage positive (1.59 percent) found in active-duty Navy personnel in 1969 and the percentage positive (5.2 percent) found in a study of Navy and Marine Corps recruits between 1958 and 1969. (Am J Public Health 1990; 80:435-438.)
Introduction Since the early 1800s, the Medical Department of the US Navy has recognized the high transmission potential of tuberculosis. 1 Not only is there an increase in risk of exposure from world-wide travel but, as epidemiological studies have demonstrated, environmental conditions aboard ships are ideal for transmission.2-4 Early attempts at TB control included screening sailors prior to an extended cruise and rejecting "all persons who were believed to be of unsound constitution."' Today, the Navy's tuberculosis control program includes tuberculin skin test screening, contact investigation, and treatment of active cases and selected skin test reactors.5 The Naval Medical Command directs all personnel whose previous test was negative to be periodically skin tested by the Mantoux method using 5 tuberculin units (TU) Purified Protein Derivative (PPD).5 Annual screening is done on individuals assigned to operational units and to areas where possible exposure to tuberculosis is high, i.e., members of deployable Navy and Marine Corps units, shipboard personnel, and health care personnel. Sailors in low-risk areas, such as shore-based personnel in the United States, are tested every three years. A person with induration measuring 10 mm or greater 48 to 72 hours after the administration of a 5 TU skin test is considered a "tuberculin reactor."5 A new reactor is defined as "a person who has become a reactor within the past three years," and persons who are found to be reactors for the first time but whose prior tuberculin status is unknown. Since earlier studies indicated that a new reactor rate of 1 to 2 percent of personnel tested could be expected in many Navy and Marine Corps settings, the Naval Medical Command recommends a search for active cases of tuberculosis when the rate of new reactors exceeds 2.5 percent in groups of approximately 100 or more personnel.5 This report examines tuberculosis skin testing in the Navy from 1980 to 1986. Comparisons are made over time in and recruits Navy and Marine Corps active-duty personnel stationed in various geographic locations.
Methods Each month, all outpatient facilities ofthe Naval Medical Command report the number of PPD tests performed and the number of reactors. Information on age, sex, race, and the exact size of the reaction is not recorded, however. In this study, computerized files of skin test results for the period January 1980 to December 1986 were analyzed. Reports are received each month from approximately 600 shore-based facilities and from over 500 ships. Approximately 25 percent of the shore-based facilities are located outside of the United States. It is important to note that the location of the reporting facility may not necessarily be the location of the tuberculosis contact. Data from shore-based facilities may include skin test results on individuals from ships during port visits as well as results on individuals transferred to a facility from a different location. Although these tests are administered and read by a number of different medical personnel, the Naval Medical Command provides very specific instructions on the administration and reading of these tests.5 Therefore, the overall results of the skin tests from different locations are generally comparable. Tubersol (Connaught, Inc., Swiftwater, PA) was used for the skin testing during the period of this study. For the 1980 to 1986 study period, the total number of skin tests performed in active-duty personnel fluctuated from a high of 373,747 in 1983 to a low of 287,251 in 1986. Average annual active-duty strength increased from 720,832 in 1980 to 805,128 in 1986. Consequently, approximately 40-50 percent of the total force was tested annually. The mean age of active-duty personnel increased from age 25.0 years in 1980 to age 26.1 years in 1986. The mean sex ratio of Navy and Marine Corps personnel changed from 16:1 (male:female) in 1980 to 11:1 in 1986. For recruit personnel, approximately 83 percent were between the ages 17 to 21 years during the study period. The percentage of both Black and Hispanic recruits increased during the period 1981 to 1986 from 12 percent to 17 percent for Blacks and from 4 percent to 9 percent for Hispanics.
Address reprint requests to Eleanor R. Cross, Associate Investigator, Division of Epidemiology, Department of Infectious Diseases, Naval Medical Research Institute, 12300 Washington Avenue, Rockville, MD 20852. Dr. Hyams is Head of the Division of Epidemiology at NMRI. This paper, submitted to the Journal April 4, 1989, was revised and accepted for publication September 20, 1989.
Results Between 1980 and 1986, a total of 2,306,533 tests were read for all active-duty Navy and Marine Corps personnel, 0.97 percent of which were positive. The rate of positive tests decreased from a high of 1.43 percent in 1980 to a low of 0.80
AJPH April 1990, Vol. 80, No. 4
435
CROSS AND HYAMS 2.00
percent in 1983. In 1983, this downward trend changed, and from 1984 to 1986 the percentage of positive tests either remained the same or increased (Table 1, Figure 1).
81
Shore-based Facilities
x
In shore-based facilities located inside of the continental United States (CONUS), a total of 1,319,610 tuberculin skin tests were read, of which 1.00 percent were positive. The percentage of positive tests dropped from a high of 1.41 percent in 1980 to a low of 0.83 percent in 1983. After 1983, the rate of positive tests either rose or remained the same (Figure 2). The average percentage of positive tests in shore-based facilities located outside the continental United States (OCONUS) was higher (1.61 percent) but followed a very similar trend (Figure 2). By location of shore-based facilities, the highest frequency of positive tests was in the Philippines (3.10 percent), followed by Japan (2.90 percent), Korea (2.00 percent), Guam (1.88 percent), Bahrain (1.66 percent), and Okinawa (1.40 percent). By US Naval District, skin test positivity was highest in the Northwestern United States (1.79 percent) and Northern California (1.77 percent) (Table 1, Figure 3). The lowest rates were found in the North Central area (0.46 percent). Positive TB Skin Tests Aboard Ships Of 814,887 skin tests read aboard ships, 0.78 percent were positive. The positive rate was higher in ships based in the Pacific area (0.98 percent) than for ships based in the Atlantic (0.62 percent). As in shore-based facilities, there was a general downward trend in both areas from 1980 to 1982, especially in the Pacific. After 1982, the rates of positive tests remained fairly stable (Table 1, Figure 4).
a
-1
11i50
1
s.-II-
I ,
(IC
\
Shore-based Total Stipboard
0.50
-
0.00
-
z
1981
1980
1 983
1982
1984
1985
1986
FIGURE 1-Frequency of Positive Tuberculin Tests in all Active-duty US Naval and Marine Corps Personnel, in all Shore-based Naval Medical Facilities, and in all ships, 1980-86
of recruits with a positive PPD skin test has remained relatively stable at between 1.28 and 1.23 percent. Discussion
The results of this study show a downward trend in the frequency of positive TB skin tests from 1980 to 1983. After 1983, the percentage of positive tests either remained stable or increased. It is noteworthy that these general trends occurred in all population groups of active-duty US Navy and Marine Corps personnel. The reason why different populations tested in different areas of the world exhibited such closely similar patterns of positive tests could not be determined. The data indicate, however, that the threat of TB infection is greatest in the Pacific for both shore-based and shipboard military personnel.
Navy and Marine Corps Recruits
Between 1980 and 1986, a total of 618,074 skin tests were performed on recruits, 1.45 percent of which were positive (Table 1, Figure 5). The highest percentage of positive tests (1.82 percent) was found in 1981. Since 1984, the percentage
TABLE 1-Percent Positive Tuberculin Reactors In Active-duty US Navy and Marine Corps Personnel and In Recruits, 1980-86 Number Reactors/Number Read x 100 R Read Location
Average 1980-86
1980
1981
1982
0.87
211232
1.151939 168485
0.83 2296 1860
2068 1.00 206074
1402 o.78 179945
1.06 149433 1578
1.26 24231-
11825182
23 1.53 27643
1.42 31287-
1.89-31905
1.07 16020
1 52
1.25
CONUS
1.00 1319610 13248
1.41 167518 236
1.18 199209 2355
1622 0.84 193872
OCONUS
1.61
-5 2.26 24140
1.93 2051
1491646
17203
290
191658
2750
219710
1986
2491 1.07 233717
1 16 318616 -368
Shore-based
1985
27 0.82 340588
1.43 305937 4385
Total
1984 0.92 356926 28
0.97 2306533 228
Total
1983
0.812604 323468 088
1927
218103
2978 0.80 373747
087
2158
248741
1847
0.92 287251 264
Atlantic
420 0.91 4839
1.33 6699
0.97 5245 52
47 0.89 5274
0.80 55244
1.26 7791 -79
0.4621... 11069
0.83 40 479
Pacific
1.87 125640 235
2.61 17442 44-2
2.25 15256 344
21.36 18957
1.2929545 19656
1.64 19852 32
1.95-021 20218
2.25 14259 32
0.78 814887 638
1477 1.29 114279
939 0.95 98906
677 0.64 105365
0.66 125006 820
-792 0.64 123209
0.72 129356 937
0.59 70118798
Atlantic
2-2 0.62 454836
478 0.83 57459
0.77 54535-
0.53 57699-
0.52 73617-
0.60 69837 e9293
71 0.66 71881
0.46 69606
Pacific
0.98 360051 380-
1.76 56820-
-181.17 44371
0.78 47666-
0.85 51389-
0.70 53372-
0.81 57475
0.78 48958-
Recruits
-m 1.45618074
1.76-13 84824
1.8292689 -"
1.3197283 -'
1.57 95853 '506
1.28.22363 106640
1.2787262 -'
-"0 1.2373723
Shipboard Total
436
AJPH April 1990, Vol. 80, No. 4
TUBERCULIN SKIN TESTING IN NAVY PERSONNEL 3 00 -
8
8
x
x
a
a
LU
2
