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Tuberculosis among newly arrived foreign spouses before citizenship in Taiwan, 2006–2011. M-M. Kuan,* H-L. Yang,* H-S. Wu*†. *Centers for Disease Control, ...
INT J TUBERC LUNG DIS 18(8):000–000 Q 2014 The Union http://dx.doi.org/10.5588/ijtld.13.0809

Tuberculosis among newly arrived foreign spouses before citizenship in Taiwan, 2006–2011 M-M. Kuan,* H-L. Yang,* H-S. Wu*† *Centers for Disease Control, Taipei, †School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan SUMMARY BACKGROUND:

Taiwan’s criterion for admissions of new immigrants is a normal chest X-ray (CXR). Subsequent tuberculosis (TB) screening for new foreign spouses is mandatory before acquiring citizenship. O B J E C T I V E S : To estimate the TB burden among newentry foreign spouses and their close contacts. R E S U LT S : Of 768 new foreign spouses with TB, of whom 98.6% were female, 721 (94.0%) had come from South-East Asian countries (Viet Nam, Indonesia, Philippines and Thailand) or China. Rates of TB (40.3–176.2 per 100 000/year) among newly emigrant wives aged 20–49 years were 1.7- to 7.3-fold higher than among Taiwanese females of corresponding ages. TB prevalence among the 2698 close contacts of 768 foreign

spouse index cases was 1.2%, according to a 2-year follow-up investigation. Respectively 87.9% (675/768) and 11.1% (85/768) of all TB cases had abnormal and normal CXRs; of these, 35.4% (239/675) of patients with an abnormal and 14.1% (12/85) of those with a normal CXR were smear-negative, culture-positive. C O N C L U S I O N S : Foreign wives from endemic countries had a relatively high risk of TB. Regular TB screening of foreign spouses within at least 1–2 years of entry from TB-endemic regions, rather than after application for citizenship, is recommended. A more sensitive TB test could facilitate better diagnosis. K E Y W O R D S : tuberculosis; foreign spouses; nationwide surveillance database; close contacts

TUBERCULOSIS (TB) in high-income countries primarily occurs among foreign-born persons, often as a result of immigration1 and the reactivation of remotely acquired, latent tuberculous infection (LTBI) among native-born persons. Immigrants may arrive with active TB, reactivate prior tuberculous infection after arrival from high TB burden regions or may acquire LTBI in the country of emigration. Taiwan is a medium TB burden country, with approximately 16 000 TB cases per year, and an incidence of approximately 57 per 100 000 population. TB is a notifiable disease that must be reported within 7 days of diagnosis. Approximately 70% of TB patients in Taiwan are aged 750 years. Taiwan’s immigrant TB control policy consists of screening for active TB cases using chest radiograph (CXR). In 2006–2011, foreign workers were screened prior to entry into Taiwan; those who were TBpositive on CXR or who had signs and symptoms of TB at any time after entry were not allowed to enter or remain in Taiwan. However, foreign spouses were excluded from this prohibition, and were either treated for TB or given health approval for admission. However, Taiwan’s TB screening policy among

foreign workers has been updated since January 2014. The current policy is to provide anti-tuberculosis treatment for foreign workers with TB and relocation only in case of extensively drug-resistant TB (XDR-TB). The present study examines TB among foreign spouses who have recently arrived in Taiwan (defined as those without citizenship who were given permission to stay .6 months within 4–6 years of arriving in Taiwan), across ethnicities. We assessed TB incidence by analysing nationwide data obtained from the National Notifiable Diseases and Surveillance System of the Taiwan Centers for Disease Control (TCDC), Taipei, Taiwan.

METHODS Definition of tuberculosis cases A TB case was defined as a patient with bacteriologically confirmed or clinician diagnosed TB.2 TB cases were categorised as follows:2 1) smear-positive pulmonary TB, 2) smear-negative pulmonary TB, and 3) extra-pulmonary TB.

Correspondence to: Mei-Mei Kuan, Centers for Disease Control, 6 Linsen South Road, Taipei 10050, Taiwan. Tel: (þ886) 2 2395 9825. Fax: (þ886) 2 2395 9833. e-mail: [email protected] Article submitted 12 November 2013. Final version accepted 27 March 2014.

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Foreign spouses with tuberculosis According to Taiwan’s current policy, a newly arrived foreign spouse is defined as the spouse of a Taiwanese national who has obtained permission to stay .6 months but who has not yet acquired citizenship or nationality within 4 years of arriving in Taiwan from a country other than China or within 6 years of arriving from China. All new entrants had normal CXRs. TB screening among new foreign spouses included active diagnostic methods that are mandatory before acquiring citizenship or hospitalisation due to clinically or laboratory-diagnosed illness at any time between entry and application for citizenship.3 Data collection Since 2001, information on TB in Taiwan has been entered into a centralised, internet-based case management system known as the National Surveillance Network of Communicable Disease (NSNCD). Contact investigation data have been entered into the NSNCD and linked to the relevant index cases since 2004.3 This was a 6-year population-based study with retrospective data collection. Data on index cases with TB or close contacts in this study were obtained from the NSNCD from 2006 to 2011. Population data by year, including data on Taiwanese nationals aged 20–49 years and new foreign spouses, were obtained from the periodic official publications of the Ministry of the Interior and the National Immigration Agency.4 Surveillance of close contacts TB patients and their close contacts were followed via the TB surveillance system. During the 2-year tracking periods used in this study, close contacts of index TB patients were investigated and automatically alerted for subsequent intervention. We collected data on TB onset from 2691 close contacts of 768 foreign spouse index cases over a period of 12 months and 13–24 months before exposure, and for 12 months or 13–24 months following exposure to index cases (foreign spouses). The rationale for this window was that the majority of instances of TB transmission to close contacts would occur within the first 2 years of contact with the index case and might decline in subsequent years. 5 In our analysis of the age distribution of close contact cases in the post-24 month exposure categories, we compared the numbers of peak groups for patients aged 0–14, 35–44 and 765 years vs. non-peak groups for patients aged 15–24, 25–34, 45–54 and 55–64 years using analysis of variation (ANOVA). Statistics Annual TB incidence rates (per 100 000) were calculated using data collected from official databas-

es. Data on all TB cases among foreign spouses of the various nationalities were obtained from the Taiwanese CDC and were categorised according to the respective number of new admissions. The strength of the associations between the pairs of variables (our estimated incidence rates in Taiwan for each nationality vs. incidence rates estimated by the World Health Organization [WHO] for the countries of origin) was calculated using Spearman’s rank order correlation. The relative risk of TB was calculated as the TB incidence rate of the target group, e.g., foreign spouses aged 20–49 years, divided by the TB incidence rate of the reference group. For example, the incidence rate of a reference group, e.g., the rate of TB among Taiwanese females aged 20–49 years, was 23.9/100 000 person-years from 2006 to 2011.6 Ethics statement The study was approved by the Institutional Review Board of the Taiwanese CDC (approval no. TwCDCIRB100025).

RESULTS Demography of foreign spouses and those with tuberculosis The majority of new foreign spouses assessed within 4–6 years of arrival in 2006–2011 originated from the following South-East Asian countries: Chinese (n ¼ 93 066), Vietnamese (n ¼ 31 496), Indonesian (n ¼ 6057), Filipino (n ¼ 2928), Thai (n ¼ 6483) and Malaysian (n ¼ 1390); of these, 98.6% were female (Table 1). Among all newly arrived foreign spouses assessed .6 months and within 4–6 years after arrival, 768 TB cases (1.4% male) in all categories (pulmonary and extra-pulmonary TB) were notified from 2006 to 2011 (Table 1); 96.4% were aged 20–49 years and 3.6% 750 years. Most (721/768, 93.9%) were from Viet Nam (42.84%), China (37.6%), Indonesia (8.7%), the Philippines (2.7%) and Thailand (2.0%) (Table 1). Tuberculosis incidence among foreign spouses Three highly TB-endemic countries (Viet Nam, Indonesia and the Philippines) were among the top five countries of origin, for which the 2011 WHO estimated TB incidence rate was 187–270 cases/ 100 000, with 119.5–174.1/100 000 admissions/year. The remaining two were China, with an estimated incidence of 78 cases/100 000, with 51.8/100 000 admissions/year, and Thailand, with an estimated incidence of 124 cases/100 000 and 38.6/100 000 admissions/year (Table 1). The average TB incidence among foreign spouses in Taiwan who emigrated from Viet Nam, Indonesia, the Philippines, China and Thailand was significantly positively associated with the 2011 WHO estimates

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65 (8.5) 675 (87.9) 222 (28.9) 404 (52.6)

AFB sputum smear-positive

Culture-positive

94

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174.1 199 172 —

TB incidence rates for all foreign spouses, 100 000/ year

2011 WHO-estimated TB incidence rates for all ages, 100 000/year

Age-specific (20–49 years)TB incidence rates for foreign spouses, 100 000/year

Age-specific (20–49 years) incidence rates for female Taiwanese, 100 000/year — 2.2

51.7

75

51.8





93.5

93 066

2 (1.3)

155

81

21 261

268

— 273 (3 males) 16

289 (37.6) 3 286

China

7.3



173.4

187

184.4





98.4

6057

0

28

16

13 52

54

— 64 (2 males) 3

67 (8.7) 2 65

Indonesia

5.1



121.5

270

119.5





93.7

2928

0

6

2

2 17

19

— 20 1

21 (2.7) 0 21

1.7



40.7

124

38.6





69.5

6483

0

9

5

3 12

12

— 15 (4 males) 0

15 (2.0) 4 11

Thailand

Foreign spouses, n Philippines 1 1















1390

0

1

0

0 2

2

— 1 (1 males) 1

2 (0.3)

Malaysia















0

16

10

1 19

21

— 20 (1 males) 1

22 (2.9) 1 21

Other

















0

14

14

0 22

23

— 23 0

23 (3) 0 23

Unknown



23.9







5 441 422

23 193 518





1%

76%

36.1%

4.5% 91.0%

95.5%

984 females 7 803 females 15 222 females

75 804 50 066 25 738

Taiwanese

* Including 1) smear-positive pulmonary case; 2) smear-negative pulmonary case (diagnostic criteria included at least two AFB-negative sputum smear results; CXR abnormalities consistent with active pulmonary TB, decision by a clinician to treat with a full course of anti-tuberculosis chemotherapy, or positive culture but AFB-negative sputum results; 3) extra-pulmonary case: patient with TB of organs other than the lungs; patients in whom both pulmonary and extrapulmonary TB had been diagnosed were classified as pulmonary TB. † Includes pulmonary TB cases with extra-pulmonary involvement. ‡ Extra-pulmonary TB only. § Resistant to at least isoniazid and rifampicin. TB ¼ tuberculosis; CXR ¼ chest radiography; AFB ¼ acid-fast bacilli; MDR-TB ¼ multidrug-resistant TB; WHO ¼ World Health Organization.

7.2



Annual average female Taiwanese population aged 20–49 years

TB relative risk (foreign spouse vs. Taiwanese female)



99.7

31 496

2 (1.2)

175

Annual average Taiwanese population, n

Average annual admissions of foreign female spouses; %

Average annual admissions of foreign spouses, n

4 (0.1)

304

703 (91.5)

Pulmonary TB†

Extra-pulmonary TB‡ Abnormal CXR

MDR-TB§

— 323 4

— 740 (96.4) 28 (3.6) 25 289

329 (42.8) 0 329

Viet Nam

768 11 (1.4) 757 (98.6)

All TB, n (%)* Male Female Age, years ,20 20–49 750

Total n (%)

Characteristics of TB cases among foreign spouses in Taiwan, 2006–2011, by nationality

Characteristics

Table 1

TB among new foreign spouses in Taiwan

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(R ¼ 0.64, with the following Spearman’s rank order correlation: 51.8, 174.1, 184.4, 119.5 and 38.6 vs. 75, 199, 187, 270 and 124) (Table 1). Relative risk of tuberculosis among foreign female spouses With regard to the average age (20–49 years) and sexspecific incidence rates from 2006 to 2011, TB incidence among foreign female spouses from the top five countries of origin was 40.7–176.2/100 000/ year compared to 23.9/100 000/year among female Taiwanese, representing 6.5% of all Taiwanese with TB (Table 1, Figure 1).6 As such, the average relative risk of developing TB among foreign wives from highendemic areas vs. Taiwanese females of corresponding age was 1.7–7.3, with 90.1% (692/768) emigrating from Indonesia, Viet Nam, the Philippines, Thailand or China (Table 1, Figure 1). Analysis of laboratory diagnostics Of the 768 TB cases, 675 (87.2%) had an abnormal CXR; 193 (28.6%) were smear-negative, culturepositive and 195 (28.9%) were smear- and culturepositive; 85 (11.1%) had a normal CXR, of whom 12 (14.1%) were smear-negative but culture-positive and 2 (2.3%) were smear- and culture-positive (Table 1, Table 2). Overall, 28.9% (222/768) of the TB cases were sputum-positive, 52.6% (404/768) were cul-

ture-positive and 27.0% (207/768) were smearnegative but culture-positive (Table 2). Among patients with a normal CXR, 76.5% (65/ 85) were smear- and culture-negative; these were also determined to have extra-pulmonary TB. The most common sites were the meninges (n ¼ 1, 1.5%), lymph nodes (n ¼ 40, 61.5%), skin or eyes (n ¼ 2, 3.1%), bone or joints (n ¼ 5, 7.7%), pulmonary rib hydrocephalus (n ¼ 5, 7.7%), other loci (n ¼ 10, 15.4%) or unknown (n ¼ 2, 3.1%). Of the culture-positive TB patients, 1.5–1.2% of recent entrants from Viet Nam and China had multidrug-resistant TB (MDR-TB) (Table 1). Tuberculosis among close contacts Our electronic tracking investigation of close contacts (n ¼ 2691) of the 768 TB index patients among foreign spouses showed a TB prevalence of 1.2% within 2 years of exposure. Furthermore, it was estimated that 0.9% (23/2691) of close contacts developed TB within a 2-year post-exposure followup period (Table 3): respectively 0.7% (19/2691) and 0.2% (4/2691) for post-exposure periods of 12 and 13–24 months (Table 3). An additional 0.3% (8/ 2691) cases occurred within 12 months before exposure to the index case. Moreover, in the 12month post-exposure category, a significant pattern in case peaks was observed for three age groups: 0–

Figure 1 Yearly fluctuations of newly female admissions or TB incidences among foreign wives in Taiwan, 2006–2011. Fluctuations in the annual age- (20–49 years) and sex-specific (female) TB incidence rates (presented as chart bars) for new foreign wives (40.2–176.2/100 000 person-years) were 1.7- to 7.3-fold higher than among Taiwanese females aged 20–49 years (21.0–26.1/ 100 000 person-years). Admission data (presented as curves) covering all new-entrant foreign wives by nationality shows a decrease in the number of spouses from Viet Nam. TB ¼ tuberculosis.

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Table 2

Laboratory diagnostics for TB among foreign spouses in Taiwan within 4–6 years of entry, 2006–2011*

Diagnostics† Total

Overall n (%) 768

CXR normal

85 (16.5)

Smear status Smear-negative‡ Smear-positive Unknown§ Smear-positive Culture-positive Unknown§

78 65 12 (14.1) 1 2 (2.4) 2 5

Viet Nam n (%)

China n (%)

Indonesia Philippines Thailand Malaysia Other Unknown n n n n n n

329 (56.3) 289 (57.7) 36 (22) 32 25 7 (19.4) 0 1 1 3

67

21

15

2

22

23

25 (12)

15

4

3

0

2

0

25 21 3 (12) 1 0 0 0

14 13 1 0 1 1 0

2 2 0 0 0 0 2

3 3 0 0 0 0 0

0 0 0 0 0 0 0

1 1 0 0 0 0 0

0 0 0 0 0 0 0

CXR abnormal without cavity

545 (58.2) 232 (57.3) 213 (59.6)

43

11

10

2

16

18

Smear-negative Culture-negative Culture-negative Unknown

383 213 168 (30.8) 2

163 93 68 (29.3) 2

153 79 74 (34.7) 0

31 19 12 0

11 9 2 0

7 3 4 0

2 1 1 0

10 4 6 0

6 5 1 0

Smear-positive Culture-negative Culture-positive Unknown

149 (27.3) 19 130 13

65 (28) 8 57 4

53 (24.9) 8 45 7

10 2 8 2

0 0 0 0

3 0 3 0

0 0 0 0

6 0 6 0

12 1 11 0

CXR abnormal with cavity

124 (75.9)

55 (76.3)

45 (73.3)

8

6

2

0

4

4

Smear-negative Culture-negative Culture-positive

52 28 24 (19.4)

27 13 14 (25.4)

16 10 6 (13.3)

3 2 1

4 1 3

0 0 0

0 0 0

0 0 0

2 2 0

Smear-positive Culture-negative Culture-positive Unknown§

70 (56.5) 4 65 1

28 (50.9) 1 27 0

5 0 5 0

2 1 1 0

2 0 2 0

0 0 0 0

4 1 3 0

2 0 2 0

27 (60) 1 25 1

Unknown§

2

0

2

0

0

0

0

0

0

CXR abnormal: atypical symptoms

6

2

3

1

0

0

0

0

0

Smear-negative Culture-negative Culture-positive

5 4 1

2 2 0

2 1 1

1 1 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

Smear-positive Culture-negative

1 1

0 0

1 1

0 0

0 0

0 0

0 0

0 0

0 0

Unknown

8

4

3

0

0

0

0

0

1

Smear-negative Culture-negative Culture-positive Unknown§

5 3 2 3

3 2 1 1

2 1 1 1

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 0

0 0 0 1

* Number of counts (% of smear-positive TB or smear-negative, culture-positive TB). † Diagnostics: 1) abnormal CXR, associated with active pulmonary TB (e.g., infiltrate or consolidation, cavitary lesion, nodule with poorly defined margins, pleural effusion, hilar or mediastinal lymphadenopathy, bihilar lymphadenopathy, other types of miliary TB) or associated with inactive TB (e.g., discrete fibrotic scar or linear opacity, discrete nodule without calcification, discrete fibrotic scar with volume loss or retraction, discrete nodule with volume loss or retraction, any other findings suggestive of previous TB, such as upper lobe bronchiectasis); 2) atypical CXR, abnormal findings: musculoskeletal abnormalities, cardiac abnormalities, pulmonary abnormalities, any other finding that the panel physician believes needed follow-up, but is not one of the above. ‡ Extra-pulmonary TB. § No detection, failure or no record according to a population-based database. TB ¼ tuberculosis; CXR ¼ chest radiography.

Table 3

TB yield among close contacts of foreign spouse index cases

Status of cases

Overall Viet Nam

Index cases 768 Total number of close contacts 2691 TB yield before exposure 0–12 months, n (%) 8 (0.3) TB yield post-exposure within 12 months, n (%) 19 (0.7) TB yield post-exposure 13–24 months, n (%) 4 (0.2) TB prevalence post-exposure ,24 months, % 0.9 Average annual inspections of close contacts 3.5

329 1283 5 (0.4) 5 (0.3) 3 (0.2) 0.5 3.9

China 289 893 3 (0.3) 10 (1.1) 1 (0.1) 1.2 3.1

Indonesia Philippines Thailand Malaysia Other Unknown 67 200 0 3 (1.5) 0 1.5 3.0

21 103 0 0 0 0 4.9

15 40 0 0 0 0 2.7

2 5 0 0 0 0 2.5

22 111 0 0 0 0 5.6

23 56 0 1 (1.8) 0 1.8 2.4

TB ¼ tuberculosis.

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14, 35–44 and 765 years (3-peak vs. non-peak; P ¼ 0.011, using ANOVA) (Figure 2).

DISCUSSION The TB incidence rates estimated in this study for new-entry foreign spouses who had arrived in the country 4–6 years previously were lower than WHO estimates for their countries of origin7 and that of US immigrants within 2 years8 or 1 year9 of entry. However, TB rates among new Chinese immigrants to Taiwan in the last 6 years was higher than that of Chinese immigrants who had resided in the United States .2 years (52.5 vs. 26/100 000 admissions/ year).8 The 1.7- to 7-fold higher incidence of TB among foreign wives vs. Taiwanese females aged 20– 49 years may be due to early exposure to TB-endemic areas or genetic susceptibility.10 Rather than waiting for the routine health screening required before applying for citizenship, we therefore recommend

regular TB screening at least within the first 1–2 years following entry from TB-endemic regions due to the association of higher TB rates with recent arrivals. Vietnamese and Chinese spouses together comprised 80.7% of the TB burden between 2006 and 2011. However, given the annual decreasing trend in the number of new Vietnamese spouses entering the country (Figure 1), the TB burden due to Chinese spouses may exceed that of Vietnamese spouses arriving in Taiwan in the future. Taiwan is a medium TB burden country, and the majority of domestic cases (70%) occur among those aged 750 years.4 In contrast, TB cases among foreign spouses in this study occurred primarily in a younger population (aged 20–49 years), the majority of whom are from TB-endemic countries. Regular health examinations using CXR are currently provided for Taiwanese persons aged 765 years. It is time to consider including more sensitive TB screening for foreign spouses at least within 1–2 years of entry.

Figure 2 TB surveillance among close contacts (2691 cases) of foreign spouse index patients (768 cases) based on an electronic surveillance system. A) Proportion of TB among the top three categories of close contacts with TB by nationals 0–12 months before exposure and 0–12 or 13–24 months post-exposure to the index case. B) Age distributions of close contacts with TB 0–12 months before exposure and 0–12 months post-exposure to the index case. In categories of postexposure: a significant pattern of three peaks at age 0–14, 35–44, 765 vs. 15–24, 25–34, 45–54, 55–64 years was observed (i.e. 3-peak vs. non-peak: P , 0.05 using analysis of variation). TB ¼ tuberculosis.

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Moreover, a more comprehensive TB screening policy, similar to the LTBI screening policy for immigrants adopted by the United States9 and other industrialised countries with a low TB burden1 could be considered for Taiwan’s next generation policy. In terms of diagnostics, the 11.1% (85/768) of TB cases overall and 2.8% (20/703) of pulmonary TB cases with a normal CXR indicates that these cases were passively identified during treatment and not by active CXR screening (Table 2); 16.5% (14/85) of these patients were later diagnosed as having TB (2 smear-positive and 12 smear-negative but culturepositive). This again implies that applying a more sensitive point-of-care TB screening test could facilitate earlier identification and intervention. Furthermore, among TB cases with a normal CXR or abnormal CXR with or without cavities, respectively 2.4% (2/85), 56.5% (70/124) and 27.3% (149/545) were diagnosed as smear-positive, the group considered to have the highest risk of transmission. A further 14.1% (12/85), 19.4% (24/124) and 30.8% (168/545), respectively, were diagnosed as smearnegative but culture-positive TB, which has an intermediate transmission rate. Overall, 26.7% (205/768) were diagnosed as smear-negative but culture-positive. Smear-positive sputum is most infectious, with 106–109 acid-fast bacilli/ml; there are fewer bacilli in the sputum of smear-negative individuals.11 However, a single bacillus is sufficient to cause infection,12 and TB transmission via airborne droplets depends on many factors, including the nature of the exposure, ventilation, and the duration and intensity of exposure.11 According to WHO guidelines, treatment in smear-negative pulmonary TB patients should therefore not be neglected or delayed. An easier, more rapid, more sensitive and less expensive tool for point-of-care testing will facilitate the rapid diagnosis of13 those with normal CXR and smear-negative but culture-positive cases14 and accelerate TB control interventions. With regard to the monitoring of close contacts, compared to a report in the Netherlands, a TB prevalence of 1.2% among 2691 close contacts of 768 foreign spouses (vs. 1.2% among 4334 contacts of 415 immigrant index cases) was observed.15 We further determined rates of TB of respectively 0.3%, 0.7% and 0.2% 12 months before exposure and 12 and 13–24 months post-exposure. This indicates that close contacts such as household members or cohabitants should be targeted for future TB control interventions in Taiwan. The age of close contacts with previous exposure, with a peak at age 45 and a shift to three peaks at ages 0–14, 35–44 and .64 years, suggests that these age categories may comprise family members who were more susceptible to TB transmission from the index case (Figure 2). Moreover, some close contacts had TB before exposure to the foreign spouse with TB was identified (data not

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shown), indicating that some cases of TB in foreign spouses may have been transmitted from indigenous TB cases. However, further evidence is required to identify potential sources of infection. A strength of this study is the inclusion of nationally representative data on all TB cases reported to the TCDC, with links to all the regional mycobacterial contract laboratories. A limitation of this study was that age-specific TB rates were underestimated as a result of using each national’s admission or each admission of female foreign spouses as the denominator, but age-stratified data were lacking. However, because the 750 year age group among new admissions constituted a minority, this bias is likely to be negligible. In any case, information bias is inherent in any retrospective comparison of relative risk data, i.e., the number of foreign spouses with TB was an estimated number derived from mandatory TB screening prior to the acquisition of citizenship, combined with passive case acquisition; however, native Taiwanese TB cases were also primarily estimated using passive case finding.

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CONCLUSION Regular health examinations including TB screening for foreign spouses from TB-endemic countries and close contacts of foreign spouses with TB should be encouraged. We recommend testing at least within 1– 2 years following entry, during the residential period, rather than waiting until application for citizenship is made. Moreover, a more sensitive and inexpensive TB screening approach or tool is likely to facilitate better TB case finding and diagnosis. Acknowledgements The authors thank all workers for reporting Taiwan TB data to the Center for Disease Control via Taiwan’s National TB Registration. We thank C-Y Lee and C-B Hsu for their help in verifying data. Conflicts of interest: none declared.

References 1 Pareek M, Baussano I, Abubakar I, Dye C, Lalvani A. Evaluation of immigrant tuberculosis screening in industrialized countries. Emerg Infect Dis 2012; 18: 1422–1429. 2 World Health Organization. Tuberculosis. Table A2.1. Definitions of tuberculosis cases and treatment outcomes. http://www. who.int/tb/publications/global_report/2008/ table_a2_1/ en/ index.html. Accessed April 2014. 3 Centers for Disease Control, Department of Health. Manual for tuberculosis control. Taipei, Taiwan: CDC, 2004. 4 Ministry of the Interior, Taiwan. Statistics: annual report, 2006–2011. Taipei, Taiwan: Ministry of the Interior http: // www.moi.gov.tw/stat. Accessed April 2014. 5 Fox G J, Barry S E, Britton W J, Marks G B. Contact investigation for tuberculosis: a systematic review and metaanalysis. Eur Respir J 2013; 41: 140–156. 6 Center for Disease Control Taiwan. Strategies for tuberculosis control: annual tuberculosis reports, 2006–2011. Taipei, Taiwan: CDC, 2006–2011.

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7 World Health Organization. Estimates of tuberculosis incidence by country, 2011. Geneva, Switzerland: WHO, 2011. 8 Chiang C Y, Enarson D A, Yang S L, Suo J, Lin T P. The impact of national health insurance on the notification of tuberculosis in Taiwan. Int J Tuberc Lung Dis 2002; 6: 974–979. 9 Liu Y, Painter J A, Posey D L, et al. Estimating the impact of newly arrived foreign-born persons on tuberculosis in the United States. PLOS ONE 2012; 7: e32158. 10 Wilkinson R J. Human genetic susceptibility to tuberculosis: time for a bottom-up approach? J Infect Dis 2012; 205: 525– 527. 11 Sepkowitz K A. How contagious is tuberculosis? Clin Infect Dis 1996; 23: 954–962.

12 Musher D M. Medical Progress: How contagious are common respiratory tract infections? N Engl J Med 2003; 348: 1256– 1266. 13 Nikam C, Jagannath M, Narayanan M M, et al. Rapid diagnosis of Mycobacterium tuberculosis with Truenat MTB: a near-care approach. PLOS ONE 2013; 8: e51121. 14 Cain K P, Benoit S R, Winston C A, Mac Kenzie W R. Tuberculosis among foreign-born persons in the United States. JAMA 2008; 300: 405–412. 15 Mulder C, van Deutekom H, Huisman E M, et al. Coverage and yield of tuberculosis contact investigations in the Netherlands. Int J Tuberc Lung Dis 2011; 15: 1630–1637.

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TB among new foreign spouses in Taiwan

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RESUME

Une radio pulmonaire (CXR) normale fait partie des crit`eres d’admission de nouveaux immigrants a` Taiwan. Un d´epistage de la tuberculose (TB) est ensuite obligatoire pour les conjoints e´ trangers avant d’obtenir la citoyennet´e. O B J E C T I F S : Estimer le fardeau de la TB parmi les conjoints e´ trangers r´ecemment entr´es et leurs contacts proches. R E´ S U LT A T S : Des 768 nouveaux conjoints e´ trangers atteints de TB (dont 98,6% de femmes), 721 (94,0%) venaient de pays du Sud-est asiatique (Viet Nam, Indon´esie, Philippines et Tha¨ılande) ou de Chine. Le taux de TB (40,3–176,2 par 100 000/ann´ee) parmi les e´ pouses r´ecemment immigr´ees ag´ ˆ ees de 20–49 ans e´ taient 1,7- a` 7,3 fois plus e´ lev´e que ceux des femmes Ta¨ıwanaises de mˆeme age. ˆ De plus, la pr´evalence de la CONTEXTE :

TB parmi les 2698 contacts proches de 768 cas index d’´epouses e´ trang`eres e´ tait de 1,2% pendant un suivi de 2 ans. En ce qui concerne le diagnostic de laboratoire, 87,9% (675/768) ou 11,1% (85/768) de tous les cas de TB avaient une CXR anormale ou normale comprenant respectivement 35,4% (239/675) ou 14,1% (12/85) de cas a` frottis n´egatif mais a` culture positive. C O N C L U S I O N S : Les e´ pouses e´ trang`eres venant de pays d’end´emie avaient un risque relativement e´ lev´e de TB. Il est donc recommand´e de mettre en œuvre un d´epistage r´egulier de la TB a` leur adresse au moins dans les 2 premi`eres ann´ees suivant leur arriv´ee d’une r´egion d’ende´ mie tuberculeuse plut ot ˆ que d’attendre la candidature a` la citoyennet´e. Un test plus sensible pourrait permettre un meilleur diagnostic.

RESUMEN M A R C O D E R E F E R E N C I A: En Taiwa´n, una condicion ´ para la admision ´ de los nuevos inmigrantes es una autorradiograf´ıa de torax ´ normal (CXR). En adelante, la deteccion ´ sistema´tica de la tuberculosis (TB) en los nuevos conyuges ´ extranjeros es obligatoria antes de adquirir la nacionalidad. O B J E T I V O S: Calcular la carga de morbilidad por TB en los conyuges ´ extranjeros reci´en llegados al territorio y en sus contactos cercanos. R E S U L T A D O S: Noventa y cuatro por ciento de los nuevos conyuges ´ extranjeros con TB (721/768), de los cuales el 98,6% era de sexo femenino, proven´ıan de pa´ıses del sureste asia´tico (Viet Nam, Indonesia, Filipinas y Tailandia) o de la China. Las tasas de TB de las esposas que reci´en inmigraban (40,3–176,2 por 100 000 habitantes por ano), cuya edad oscilaba entre ˜ 20 y 49 anos ˜ fueron de 1,7 a 7,3 veces ma´s altas que las tasas de las mujeres taiwanesas de edad equivalente. Adema´s, tras un seguimiento de 2 anos, se calculo´ que la ˜ prevalencia de TB en los 2698 contactos cercanos de los

768 casos nuevos en los conyuges ´ extranjeros fue 1,2%. En cuanto se refiere a los medios diagnosticos ´ de todos los casos de TB, en el 87,9% se observaron ima´genes CXR anormales (675/768) y en el 11,1% ima´genes CXR normales (85/768); del primer grupo, el 35,4% presento´ baciloscopia negativa y cultivo positivo (239/675) y 14,1% en el segundo grupo (12/85). ´ N: Las esposas extranjeras de los CONCLUSIO inmigrantes que provienen de pa´ıses donde la TB es end´emica, presentan un riesgo relativamente alto de padecer TB. Se recomienda firmemente practicar la deteccion ´ sistema´tica de la TB a las esposas extranjeras de manera periodica ´ durante un seguimiento de por lo menos 1 o 2 anos despu´es de su primera llegada al ˜ territorio, cuando provienen de regiones donde la TB es end´emica, en lugar de retrasar el control hasta la solicitud de la ciudadan´ıa. La utilizacion ´ de una prueba diagnostica ´ ma´s sensible contribuira´ a un mejor el diagnostico. ´

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Queries for jtld-18-08-14 1. Author: ok as added? Ed 2. Author: meaning? Ed 3. Author: meaning? Ed

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