87
Tuberculosis Risk in US Peace Corps Volunteers, 1996 to 2005
Paul Jung, MD, MPH and Richard H. Banks, MA
Epidemiology Unit, Office of Medical Services, Peace Corps, Washington, DC, USA
DOI: 10.1111/j.1708-8305.2008.00184.x
Background. With the popularity of international travel increasing, more travelers in endemic areas may increase their
risk of tuberculosis (TB). We analyzed Peace Corps data to assess the risk of TB in long-term travelers from the United
States.
Methods. We analyzed purified protein derivative (PPD) conversion and acute TB case data from the Peace Corps
Epidemiological Surveillance System as well as postservice claims data. We calculated the risk of PPD conversion and
active TB in all countries with Peace Corps Volunteers between 1996 and 2005 and compared these risks with other
published data.
Results. The overall incidence rates for positive PPD conversions and active TB cases are 1.283 and 0.057 per 1,000
Volunteer-months, respectively. The Africa region had the highest PPD conversion rate of 1.467 conversions per 1,000
Volunteer-months as well as the highest active TB rate of 0.089 cases per 1,000 Volunteer-months. Per-country incidence rates for PPD conversions and active TB cases ranged widely from 0.000 to 5.514 cases and 0.000 to 2.126 cases
per 1,000 Volunteer-months, respectively. In countries identified as “high risk,” there were 1.436 cases of PPD conversions and 0.084 cases of active TB per 1,000 Volunteer-months.
Conclusions. Peace Corps Volunteers have significantly higher rates of TB when compared to the average US population but much lower than those reported for travelers to highly endemic countries. Volunteers assigned to highly endemic
countries still have a lower risk compared to other travelers to those same countries. Keeping in mind that Peace Corps
Volunteers are a unique population, these data may be useful in providing medical advice to long-term travelers.
R
ecent media reports related to extensively drugresistant tuberculosis (TB) have renewed concerns about this pernicious disease.1 TB remains
one of the most prevalent diseases in the world, with
an estimated 14.6 million cases worldwide and
nearly 1.7 million deaths from TB in 2004.2 The
United States has had some success in reducing TB
cases each year since 1993 to a current incidence
rate of 4.8 cases per 100,000 population in 2005.3
However, with the popularity of international travel
increasing, especially to areas of high risk such as
Africa,4 more travelers in endemic areas may
increase their risk of TB.
Published research has shown a substantial
increase in TB risk among travelers to highly endemic areas. The most recent study showed a purified protein derivative (PPD) conversion rate of 2.8
Corresponding Author: Paul Jung, MD, MPH, Epidemiology Unit, Office of Medical Services, Peace Corps,
#5102, 1111 20th Street, NW, Washington, DC 20526,
USA. E-mail: [email protected]
cases per 1,000 person-months of travel among
Dutch travelers5 as well as an active TB rate of 0.6
cases per 1,000 person-months of travel. We found
no recent systematic data specifically related to TB
risk in US travelers.
US Peace Corps Volunteers spend 27 months
living in countries often endemic for TB and are
thus a unique population in which to assess risk. All
Peace Corps Volunteers are screened with a PPD
test prior to service and receive a PPD test at midservice and upon completion of service. Clinical
testing for active TB, as well as screening PPD tests,
is also provided at any time during service when
exposure may have occurred. Peace Corps also
provides a postservice claims system for reimbursement of treatment costs for service-related illnesses, including both latent and active TB.
Since President John F. Kennedy established the
Peace Corps on March 1, 1961, more than 187,000
Peace Corps Volunteers have been invited by 139
host countries to work on issues including education, business development, and health.6
© 2008 International Society of Travel Medicine, 1195-1982
Journal of Travel Medicine, Volume 15, Issue 2, 2008, 87–94
88
Table 1
Jung and Banks
Peace Corps countries—Europe and Central Asia
PPD conversion
rate per 1,000
Volunteermonths
Total active
TB cases
Active TB
rate per 1,000
Volunteermonths
Peace Corps
country
Years as Peace
Corps country
Months with
Volunteers,
1996–2005
Albania
Armenia
Azerbaijan
Bulgaria
Czech Republic
Estonia
Georgia
Hungary
Jordan
Kazakhstan
Kyrgyzstan
Latvia
Lithuania
Macedonia
Moldova
Mongolia
Poland
Romania
Russia Western
Slovakia
Turkmenistan
Ukraine
Uzbekistan
1996–2005
1996–2005
2003–2005
1996–2005
1996–1997
1996–2002
2001–2005
1996–1997
1997–2005
1996–2005
1996–2005
1996–2002
1996–2002
1998–2005
1996–2005
1996–2005
1996–2001
1996–2005
1996–2003
1996–2002
1996–2005
1996–2005
1996–2005
42
117
27
119
17
75
56
9
90
120
115
78
79
70
120
119
66
119
85
79
114
120
106
208.424
674.626
113.103
1,212.449
72.731
230.530
208.329
90.680
393.350
1,133.749
746.023
264.025
292.756
257.823
943.721
738.650
742.256
1,337.673
538.321
512.235
619.556
2,057.117
882.207
7
19
1
23
0
3
1
6
3
33
15
3
5
4
17
10
5
10
17
7
18
28
12
2.799
2.347
0.737
1.581
0.000
1.084
0.400
5.514
0.636
2.426
1.676
0.947
1.423
1.293
1.501
1.128
0.561
0.623
2.632
1.139
2.421
1.134
1.134
0
0
0
0
0
0
0
0
0
2
1
0
0
0
0
0
1
0
0
0
1
0
1
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.147
0.112
0.000
0.000
0.000
0.000
0.000
0.112
0.000
0.000
0.000
0.135
0.000
0.094
Total
—
—
14,270.334
247
1.442
6
0.035
Total
Volunteeryears
Total PPD
conversions
PPD = purified protein derivative; TB = tuberculosis.
To quantify TB risk for long-term travelers from
the United States, we analyzed Peace Corps epidemiological surveillance data to assess the risk of TB
in countries where Volunteers served from 1996 to
2005.
Methods
We analyzed data from the Peace Corps Epidemiological Surveillance System,7 which collects monthly
Table 2
counts of specific conditions among currently serving Peace Corps Volunteers from Peace Corps
Medical Officers stationed in each Peace Corps
country. Since January 1, 1996, these reports have
included counts of PPD test conversions (defined as
an increase in induration from the baseline test using
criteria from the US Centers for Disease Control
and Prevention8), as well as cases of active TB (defined as an infection with Mycobacterium tuberculosis
Peace Corps countries—East Asia and South Asia
Total PPD
conversions
PPD conversion
rate per 1,000
Volunteermonths
Total active
TB cases
Active TB
rate per 1,000
Volunteermonths
Peace Corps
country
Years as Peace
Corps country
Months with
Volunteers,
1996–2005
Bangladesh
China
East Timor
Nepal
Philippines
Russia Far East
Sri Lanka
Thailand
1998–2005
1996–2005
2002–2005
1996–2004
1996–2005
1996–2003
1996–1998, 2005
1996–2005
77
106
43
104
120
84
34
120
323.439
478.283
92.923
1,091.636
1,216.559
388.569
72.621
733.574
3
16
1
24
6
7
0
15
0.773
2.788
0.897
1.832
0.411
1.501
0.000
1.704
0
1
0
0
0
0
0
0
0.000
0.174
0.000
0.000
0.000
0.000
0.000
0.000
Total
—
—
4,397.604
72
1.364
1
0.019
PPD = purified protein derivative; TB = tuberculosis.
J Travel Med 2008; 15: 87–94
Total
Volunteeryears
89
Tuberculosis Risk in US Peace Corps Volunteers
Table 3
Peace Corps countries—Africa
PPD
conversion rate per
Total PPD 1,000 VolunteerTotal active
conversions months
TB cases
Active TB
rate per 1,000
Volunteermonths
Peace Corps
country
Years as Peace
Corps country
Months with Total
Volunteers, Volunteer1996–2005
years
Benin
Botswana
Burkina Faso
Cameroon
Cape Verde
Central African
Republic
Chad
1996–2005
1996–2005
1996–2005
1996–2005
1996–2005
1996
119
58
120
119
120
5
1,018.828
228.657
808.225
1,315.513
449.840
39.190
8
3
15
49
4
1
0.654
1.093
1.547
3.104
0.741
2.126
0
1
0
6
0
1
0.000
0.364
0.000
0.380
0.000
2.126
55
140.561
2
1.186
1
0.593
13
81
29
36
114
119
120
120
28
120
119
114
120
119
120
115
87
119
120
7
120
107
39
64.255
764.635
103.756
123.143
674.951
825.971
1,478.360
988.260
94.188
1,340.830
863.461
811.025
1,094.935
1,580.000
647.833
1,282.116
380.624
1,022.160
1,109.848
9.810
1,325.692
763.770
132.411
1
29
2
5
0
6
12
13
6
40
21
16
23
59
7
18
4
14
21
0
11
6
2
1.297
3.161
1.606
3.384
0.000
0.605
0.676
1.096
5.309
2.486
2.027
1.644
1.750
3.112
0.900
1.170
0.876
1.141
1.577
0.000
0.691
0.655
1.259
0
1
0
1
0
0
2
0
1
2
3
1
2
1
0
1
0
1
0
0
0
0
0
0.000
0.109
0.000
0.677
0.000
0.000
0.113
0.000
0.885
0.124
0.290
0.103
0.152
0.053
0.000
0.065
0.000
0.082
0.000
0.000
0.000
0.000
0.000
120
120
6
98
1,100.860
898.913
21.676
384.627
11
11
0
7
0.833
1.020
0.000
1.517
1
0
0
0
0.076
0.000
0.000
0.000
120
71
1,129.342
371.652
12
7
0.885
1.570
1
0
0.074
0.000
—
25,389.918
446
1.464
27
0.089
1996–1998,
2003–2005
Congo
1996–1997
Cote d’Ivoire
1996–2002
Eritrea
1996–1998
Ethiopia
1996–1999
Gabon
1996–2005
Gambia
1996–2005
Ghana
1996–2005
Guinea
1996–2005
Guinea-Bissau 1996–1998
Kenya
1996–2005
Lesotho
1996–2005
Madagascar
1996–2005
Malawi
1996–2005
Mali
1996–2005
Mauritania
1996–2005
Morocco
1996–2005
Mozambique
1998–2005
Namibia
1996–2005
Niger
1996–2005
Sao Tome
1996
Senegal
1996–2005
South Africa
1997–2005
Swaziland
1996,
2003–2005
Tanzania
1996–2005
Togo
1996–2005
Tunisia (Malta) 1996
Uganda
1996–1999,
2001–2005
Zambia
1996–2005
Zimbabwe
1996–2001
Total
—
PPD = purified protein derivative; TB = tuberculosis.
confirmed by culture of the organism from a collected clinical specimen or a clinical presentation
consistent with active TB that is culture negative
but responds to treatment with appropriate anti-TB
therapy). Peace Corps surveillance data does not
include protected health information or identifying personal or demographic information, and it
does not distinguish between diagnoses made clinically or microbiologically, pulmonary or extrapulmonary cases, smear positive or negative, or
culture positive or negative.
Some Volunteers may have had PPD conversions or active TB prior to their Peace Corps
service. In each case, the reading of subsequent
PPD tests is interpreted accordingly based on
guidelines of the US Centers for Disease Control
and Prevention for placing and reading PPD tests.
All Peace Corps Medical Officers are trained to
follow these guidelines. Therefore, PPD conversions reported via the Peace Corps surveillance
system do take a Volunteer’s PPD history into
account.
J Travel Med 2008; 15: 87–94
90
Table 4
Jung and Banks
Peace Corps countries—Central America
Peace Corps
country
Years as Peace
Corps country
Months with
Volunteers,
1996–2005
Total
Volunteeryears
Belize
Costa Rica
El Salvador
Guatemala
Honduras
Mexico
Nicaragua
Panama
1996–2005
1996–2005
1996–2005
1996–2005
1996–2005
2004–2005
1996–2005
1996–2005
120
120
120
120
120
15
119
120
576.359
489.246
1,078.850
1,997.848
2,205.426
17.509
1,486.968
1,059.652
Total
—
—
8,911.858
PPD conversion
rate per 1,000
Volunteer-months
Total active
TB cases
Active
TB rate
per 1,000
Volunteermonths
2
2
14
36
32
0
43
7
0.289
0.341
1.081
1.502
1.209
0.000
2.410
0.550
0
0
1
2
1
0
2
1
0.000
0.000
0.077
0.083
0.038
0.000
0.112
0.079
136
1.272
7
0.065
Total PPD
conversions
PPD = purified protein derivative; TB = tuberculosis.
In addition to the cases reported during inservice medical care, Peace Corps Volunteers are
provided testing and evaluation immediately upon
completion of service; occasionally, Volunteers receive their examinations subsequent to completion
of service due to logistical reasons. The completion
rate of postservice PPD testing exceeds 99%. If a
Volunteer is determined to have a PPD conversion
or active TB at this point, he or she can file a claim
for treatment costs via the Federal Employees’
Compensation Act. We counted all those claims
filed for positive PPD test conversions (ICD-9 code
795.5) and active TB (ICD-9 codes 010–018) for
Volunteers who closed service between January 1,
1996, and December 31, 2005.
We calculated the total number of PPD conversions and active TB cases for each Peace Corps
country that hosted Volunteers between January 1,
1996, and December 31, 2005. Claims filed after
completion of service were counted in the year that
the Volunteer completed service.
Table 5
To calculate incidence rates, we obtained the
number of Volunteer-years for each country that
hosted Peace Corps Volunteers at any time between
January 1, 1996, and December 31, 2005. For consistency with published reports on TB risk among
travelers, we reported results based on Volunteermonths, which were calculated by multiplying
Volunteer-years by 12.
We calculated incidence rates in seven geographic
regions: Europe and Central Asia (Europe), East and
South Asia (Asia), Africa, Central America, Caribbean, South America, and the Pacific Islands. For administrative reasons, some Peace Corps posts (ie,
Malta, Niue, and Tuvalu) reported cases with another country (Tunisia, Samoa, and Fiji, respectively)
and are counted and reported as single-country units.
Posts in the Leeward Islands, Windward Islands,
and St Kitts and Nevis are combined collectively as
“Eastern Caribbean,” and data from these posts include Volunteers on Antigua, Barbuda, Dominica,
Grenada, Cariaccou, St Lucia, St Vincent, and the
Peace Corps countries—Caribbean
Peace Corps
country
Years as Peace
Corps country
Months with
Volunteers,
1996–2005
Total
Volunteeryears
Total PPD
conversions
PPD conversion
rate per 1,000
Volunteer-months
Total active
TB cases
Active
TB rate
per 1,000
Volunteermonths
Dominican
Republic
Eastern
Caribbean
Haiti
Jamaica
1996–2005
120
1,560.879
28
1.495
0
0.000
1998–2005
96
1,043.811
1
0.080
0
0.000
1996–2005
1996–2005
103
120
395.893
1,024.572
5
14
1.052
1.139
0
1
0.000
0.081
Total
—
—
4,025.155
48
0.994
1
0.021
PPD = purified protein derivative; TB = tuberculosis.
J Travel Med 2008; 15: 87–94
91
Tuberculosis Risk in US Peace Corps Volunteers
Table 6
Peace Corps countries—South America
Peace Corps
country
Years as Peace
Corps country
Months with
Volunteers,
1996–2005
Total
Volunteeryears
Total PPD
conversions
PPD conversion
rate per 1,000
Volunteer-months
Total active
TB cases
Active
TB rate
per 1,000
Volunteermonths
Bolivia
Chile
Ecuador
Guyana
Paraguay
Peru
Suriname
Uruguay
1996–2005
1996–1998
1996–2005
1996–2005
1996–2005
2002–2005
1996–2005
1996–1997
120
31
120
119
120
41
120
11
1,554.401
111.458
1,619.600
414.842
1,957.385
225.541
365.175
69.068
17
2
21
13
2
0
1
0
0.911
1.495
1.081
2.611
0.085
0.000
0.228
0.000
0
0
1
0
0
0
0
0
0.000
0.000
0.051
0.000
0.000
0.000
0.000
0.000
Total
—
—
6,317.470
56
0.739
1
0.013
PPD = purified protein derivative; TB = tuberculosis.
Grenadines. The Peace Corps operated two separate
posts in Russia (Western and Far East), and counts
from these locations were calculated separately and
are also placed in two distinct geographic regions
(Europe and Asia, respectively). Peace Corps posts in
Comoros, Cook Islands, and Seychelles each closed
in January 1996 and thus did not contribute to the
counts or Volunteer-years in this study.
The World Health Organization9 and Corbett
and colleagues10 have identified high-risk countries
with respect to TB. We examined the TB rates of
Volunteers in 19 of these countries where Peace
Corps placed Volunteers between 1996 and 2005.
Results
Over the 10-year study period, there were 44,070
Volunteers who contributed 801,780.54 VolunteerTable 7
months of service. The mean age at the start of service was 28.1 years (median 24.4 y, range 18–84 y),
with 59.3% female and 16% self-identified as an
ethnic minority. Among these Volunteers, there
were a total of 1,028 PPD conversions and 46 active
cases of TB. The overall incidence rates for PPD
conversions and active TB cases are 1.283 and 0.057
per 1,000 Volunteer-months, respectively.
There were 1,282 Volunteers (2.9%) who had a
history of a positive PPD conversion or active TB
disease prior to beginning Peace Corps service.
These 1,282 Volunteers contributed 20,116.08
months (2.5%) of service during our study period.
We were unable to distinguish how many had either
a PPD conversion or an active disease prior to
service, nor were we able to obtain specific counts of
PPD conversion or active disease during service
among those with a prior history.
Pacific Island Peace Corps countries
Months with
Volunteers,
1996–2005
Total
Volunteeryears
PPD
conversion rate
per 1,000
Volunteer-months
Total active
TB cases
Active
TB rate
per 1,000
Volunteermonths
Peace Corps
country
Years as Peace
Corps country
Fiji (Tuvalu)
50
202.773
5
2.055
0
0.000
Kiribati
Marshall Island
Micronesia
Papua New
Guinea
Samoa (Niue)
Solomon Island
Tonga
Vanuatu
1996–1997,
2003–2005
1996–2005
1996
1996–2005
1996–2001
118
5
119
66
438.905
3.088
567.003
388.249
2
0
1
1
0.380
0.000
0.147
0.215
1
0
0
0
0.190
0.000
0.000
0.000
1996–2005
1996–2000
1996–2005
1996–2005
114
54
120
120
555.181
289.569
567.006
490.932
6
1
5
2
0.901
0.288
0.735
0.339
1
0
1
0
0.150
0.000
0.147
0.000
Total
—
—
3,502.706
23
0.547
3
0.071
Total PPD
conversions
PPD = purified protein derivative; TB = tuberculosis.
J Travel Med 2008; 15: 87–94
92
Jung and Banks
Tables 1 to 7 show all countries with Peace Corps
Volunteers between January 1, 1996, and December 31, 2005, by geographic regions, the calendar
years and the total number of months in which they
hosted Volunteers, the total number of Volunteeryears for each country, the total number of PPD
conversions and active cases of TB reported for each
country within the indicated time period, and the
incidence rate per 1,000 Volunteer-months. The
total number of months that Volunteers served in
each country correlates with the number of monthly
surveillance reports that were obtained from each
country.
The Africa region had the highest PPD conversion rate of 1.467 conversions per 1,000 Volunteermonths, followed closely by the European region
with 1.442. The Asia region had a PPD conversion
rate of 1.364 per 1,000 Volunteer-months, followed
by Central America with 1.272, the Caribbean with
0.994, South America with 0.739, and the Pacific
Islands with 0.547.
The Africa region also had the highest active TB
rate of 0.089 cases per 1,000 Volunteer-months,
followed by the Pacific Islands with 0.071. Central
America had an active TB case rate of 0.065 per
1,000 Volunteer-years, followed by Europe with
Table 8
0.039, the Caribbean with 0.021, the Asia region
with 0.019, and South America with 0.013.
Per-country incidence rates for PPD conversions and active TB cases ranged widely from 0.000
to 5.514 cases and 0.000 to 2.126 cases per 1,000
Volunteer-months, respectively. Between 1996 and
2005, Peace Corps placed Volunteers in 19 countries identified as having high incidence rates of TB:
Bangladesh, Botswana, China, Congo, Ethiopia,
Haiti, Kenya, Lesotho, Malawi, Mozambique, Namibia, Philippines, Russia (Western and Far East),
South Africa, Thailand, Uganda, Tanzania, Zambia, and Zimbabwe. Table 8 shows the data for these
specific countries. In these countries, there were
1.436 cases of PPD conversions and 0.084 cases of
active TB per 1,000 Volunteer-months.
Figure 1 shows the rate of PPD conversions and
active TB among Peace Corps Volunteers per year
for 1996 to 2005. Rates for PPD conversions ranged
from 8.14 to 11.98 conversions per 1,000 Volunteers, and for active TB cases, from 0.00 to 0.93
cases per 1,000 Volunteers. Although the incidence
rates appear to be trending downward over the 10year period (trendlines show ␤ = −0.3134 and r2 =
0.4643 for PPD conversions and ␤ = −0.0746 and
r2 = 0.519 for active TB cases), a chi-square test for
Peace Corps Volunteers in high-incidence countries
Months with
Volunteers,
1996–2005
Total
Volunteeryears
PPD conversion
rate per 1,000
VolunteerTotal active
months
TB cases
Active TB
rate per 1,000
Volunteermonths
Peace Corps
country
Years as Peace
Corps country
Bangladesh
Botswana
China
Congo
Ethiopia
Haiti
Kenya
Lesotho
Malawi
Mozambique
Namibia
Philippines
Russia Far East
Russia Western
South Africa
Tanzania
Thailand
Uganda
77
58
106
13
36
103
120
119
120
87
119
120
84
85
107
120
120
98
323.439
228.657
478.283
64.255
123.143
395.893
1,340.830
863.461
1,094.935
380.624
1,022.160
1,216.559
388.569
538.321
763.770
1,100.860
733.574
384.627
3
3
16
1
5
5
40
21
23
4
14
6
7
17
6
11
15
7
0.773
1.093
2.788
1.297
3.384
1.052
2.486
2.027
1.750
0.876
1.141
0.411
1.501
2.632
0.655
0.833
1.704
1.517
0
1
1
0
1
0
2
3
2
0
1
0
0
0
0
1
0
0
0.000
0.364
0.174
0.000
0.677
0.000
0.124
0.290
0.152
0.000
0.082
0.000
0.000
0.000
0.000
0.076
0.000
0.000
Zambia
Zimbabwe
1998–2005
1996–2005
1996–2005
1996–1997
1996–1999
1996–2005
1996–2005
1996–2005
1996–2005
1998–2005
1996–2005
1996–2005
1996–2003
1996–2003
1997–2005
1996–2005
1996–2005
1996–1999,
2001–2005
1996–2005
1996–2001
120
71
1,129.342
371.652
12
7
0.885
1.570
1
0
0.074
0.000
Total
—
—
12,942.954
223
1.436
13
0.084
PPD = purified protein derivative; TB = tuberculosis.
J Travel Med 2008; 15: 87–94
Total PPD
conversions
93
Tuberculosis Risk in US Peace Corps Volunteers
Figure 1 TB rates among Peace Corps Volunteers, 1996 to 2005. TB = tuberculosis.
trend found no significant difference in either PPD
conversion or active TB rates.
Discussion
Our data show that Peace Corps Volunteers have
significantly higher rates of TB when compared
to the average US population (68.9 per 100,000
Volunteer-years vs 4.8 per 100,000 person-years in
the US population). This is likely due to their exposure in countries with far higher rates of TB than
the United States. Volunteer TB rates, however,
are much lower than those reported for other travelers to highly endemic countries (1.3 per 1,000
Volunteer-months vs 2.8 per 1,000 personmonths). Volunteers assigned to highly endemic
countries still have a lower risk compared to general
travelers (1.4 vs 2.8 PPD conversions and 0.08 vs
0.60 active TB cases per 1,000 person-months).
One limitation of this study is that the Peace
Corps Epidemiological Surveillance System does
not count the number of Volunteers who have a
particular condition but rather only the number of
cases, so we are unable to provide the number or
percentage of Volunteers who had PPD conversions or cases of active TB. However, given the nature of the disease, it is highly unlikely that a single
Volunteer would be counted as having a PPD conversion or an active case of TB more than once during their service.
Peace Corps Volunteers serve in countries with
varying levels of endemicity for TB. In addition,
Peace Corps Volunteers are typically young and
must be determined to be medically qualified for
service. Also, Volunteers have good access to medical care during their service. These factors may
affect the rate of TB infection and disease among
Volunteers when compared to typical travelers to
highly endemic countries.
Volunteers often live with host families, possibly
presenting them with greater exposure to TB compared with the typical traveler. Additionally, most
Volunteers spend a full 27 months in their host
country, which is much longer than most travel itineraries, which average 23 days.11 This may explain
the higher rate of TB among Volunteers compared
to the US population.
There is a discrepancy between countries and regions in the ratio of PPD conversions to TB cases.
For example, in the East/Southeast Asia region,
there was only 1 TB case and 72 PPD conversions
(ratio = 72), whereas in the Pacific Islands region,
there were 3 TB cases for 23 PPD conversions
(ratio = 7.7). This discrepancy may be explained by
variations in the health status of Volunteers placed
in various regions as well as variations in the types of
placement locations available in each country.
Our data examine the risk over a 10-year time period. In that time frame, although Volunteer medical services and policies with regard to TB have not
changed significantly, Volunteer site placements,
host country TB control measures, and Volunteer
job assignments may have changed within each
country. Thus, further analysis may be necessary to
determine trends in TB risk among US travelers to
these countries.
Our analysis presents PPD conversion data and
active TB incidence for several countries based on
a unique population of Peace Corps Volunteers.
These data may prove useful for clinicians and travel
advisors on the nature of the risk of TB for US travelers to other countries.
J Travel Med 2008; 15: 87–94
94
Acknowledgment
The authors acknowledge Dr David R. Hill for his
thoughtful comments on their manuscript.
Declaration of Interests
The authors state that they have no conflicts of
interest.
References
1. Wines M. Virulent TB in S. Africa may imperil
millions. New York Times. January 28, 2007.
Available at: http://www.nytimes.com/2007/01/28/
world/africa/28tuberculosis.html?th&emc=th .
(Accessed 2007 Jan 29)
2. World Health Organization. Global tuberculosis
control: surveillance, planning, financing. WHO
Report 2006. Geneva, World Health Organization
(WHO/HTM/TB/2006.362).
3. Trends in tuberculosis—United States, 2005.
MMWR Morb Mortal Wkly Rep 2006; 55(11):
305–308.
4. World Tourism Organization. “Another Record
Year for Tourism.” Press Release; January 29,
2007. Available at: http://www.world-tourism.org/
newsroom/Releases/2007/january/recordyear.htm.
(Accessed 2007 Jan 30)
J Travel Med 2008; 15: 87–94
Jung and Banks
5. Cobelens F, van Deutekom H, Draayer-Jansen I,
et al. Risk of infection with Mycobacterium tuberculosis in travelers to areas of high tuberculosis endemicity. Lancet 2000; 356:461–465.
6. “Fast Facts.” What is the Peace Corps? Available at:
http://www.peacecorps.gov/index.cfm?shell=learn.
whatispc.fastfacts. (Accessed 2007 Jan 30)
7. Bernard KW, Graitcer PL, van der Vlugt T, et al.
Epidemiological surveillance in Peace Corps Volunteers: a model for monitoring health in temporary
residents of developing countries. Int J Epidemiol
1989; 18:220–226.
8. American Thoracic Society, Centers for Disease
Control and Prevention. Targeted tuberculin testing and treatment of latent tuberculosis infection.
Am J Respir Crit Care Med 2000; 161(Suppl):
S221–S247.
9. Global tuberculosis control—surveillance, planning,
financing. WHO Report. 2006. Annex 1. Available
at:www.who.int/entity/tb/publications/global_report/
2004/annex1.pdf. (Accessed 2007 Jan 30)
10. Corbett EL, Watt CJ, Walker N, et al. The growing
burden of tuberculosis: global trends and interactions with the HIV epidemic. Arch Intern Med 2003;
163:1009–1021.
11. Freedman DO, Weld LH, Kozarsky PE, et al. Spectrum of disease and relation to place of exposure
among ill returned travelers. N Engl J Med 2006;
354:119–130.