Systematic Tuberculosis Screening in Asylum Seekers in Italy

Abstract

The preliminary findings of a tuberculosis (TB) screening of asylum seekers performed in a reception center located in northern Italy reveal a post-entry screening prevalence rate of 535 per 100000 individuals screened. This result shows that systematic use of chest radiography is a useful tool for active TB screening among asylum seekers in Italy.

tuberculosis, screening, asylum seekers, chest radiography

Global migration due to conflict or humanitarian crisis has dramatically increased in recent decades. The increasing flow of migrants arriving from countries with high tuberculosis (TB) incidence to lower-incidence European countries (<100 TB cases per million population) raises concerns of TB transmission among migrants/asylum seekers. The action framework proposed by the World Health Organization (WHO) toward TB elimination identifies migrants among the most vulnerable groups. Because the rates of active and latent TB (LTBI) in migrants often correspond to those of their countries of origin, targeted interventions are recommended in this population to address its special needs, including screening for active TB and LTBI, and appropriate treatment [1]. Different screening algorithms have been proposed and utilized in Europe [2]. However, few countries use a nationally standardized screening algorithm, with most countries using screening programs adapted to the regional level [3]. As recently reported [4, 5], there is a need for a more standardized data collection and analysis to better understand the real usefulness, cost-effectiveness, and epidemiological impact of TB screening of migrants in Europe.

We report 1-year data of post-entry TB screening of migrants (hereafter intended as asylum seekers) performed in an Italian reception center located in Bologna, Emilia Romagna region, northern Italy.

In Italy, immigration has become increasingly significant since the 1990s, when the migration flows through the Mediterranean area from unseaworthy boats began. The number of arrivals by sea to the Italian coasts was estimated to be 66000 in 2014, increasing to 153600 in 2015 [6]. In our country, the “hub and spokes” operating model for migrants’ relocation was adopted in July 2014 [7]. Upon arrival to Italy, migrants are immediately hosted in first-aid centers, called “hot spots,” located next to the coasts of southern Italy and then allocated to Italian regions. In our region, they are initially hosted in the regional temporary reception center, called “hub,” until their judicial situation is better defined, and then they are transferred to the peripheral regional centers, called “spokes.” To safeguard migrants’ health, hub is required to provide an initial medical support to the newly arrived [7], including TB screening, although there are no national guidelines defining which screening algorithm should be implemented to identify TB. Different approaches have been adopted by the various regional reception centers, and they are mainly based on TB symptom screening through a specific questionnaire [8]. In contrast, the majority of European countries are performing a chest radiograph (CXR)–based active TB screening [9].

In the Emilia Romagna region, a CXR-based TB screening to all migrants arriving to the regional hub in Bologna has been being implemented since July 2014, in collaboration with the Ministry of Interior and the Prefecture; to our knowledge, our region is the only one in Italy to have implemented systematic CXR screening of active TB at arrival.

A mobile CXR machine was installed inside the reception center, and all the individuals who agree to be registered in Italy undergo CXR the day after their arrival to the center, regardless the presence of symptoms. All the CXRs are read by an experienced radiologist within 3 days: in case of pathological findings, the hub’s medical doctor consults the infectious diseases specialist, who may recommend other investigations such as chest high-resolution computed tomography, collection of respiratory specimens, or admission to hospital. All children <5 years of age are excluded from the CXR screening and rapid pregnancy test is administered to all women of reproductive age before CXR. An individual questionnaire collecting travel history, general clinical conditions, and presence of TB-suggestive symptoms is filled with the aid of cultural mediators. Migrants screened negative for TB by CXR and symptoms receive Mantoux test and/or interferon-γ release assay after deployment from hub to spoke centers. All those found with TB or LTBI receive proper treatment managed by an infectious diseases team.

From August 2014 to July 2015, 3366 individuals were included in the screening and underwent a CXR. Of individuals screened, 82% (n = 2782) came from Africa, with 99% (n = 2741) of them from Western Africa; 17% (n = 576) were from the Indian subcontinent, and only 5 individuals (0.1%) were from Syria. Mean age was 25 (range, 18–41) years and 96% (n = 3236) of them were male. During this period, 18 new cases of active TB were diagnosed: all were males, and the mean age was 25 (range, 18–38) years; 84% (n = 15) were from West Africa and the others from the Indian subcontinent. Overall, 94% (n = 17/18) of patients were affected by pulmonary TB, whereas 1 of 18 had extrapulmonary TB. All CXRs of TB cases were suggestive of TB and the most represented radiological findings were pulmonary consolidations, micronodules, and cavitations. In patients with pulmonary TB, 33% (n = 6) were asymptomatic at diagnosis (Table 1). The bacteriological confirmation rate was 67% (n = 12/18); all cases successfully completed the treatment. The rather low bacteriological confirmation rate and the absence of symptoms in 1 of 3 of cases may be due to the detection of the disease at an early stage, with a lower mycobacterial burden. In the study period, no additional cases of TB among migrants diagnosed after the initial screening have been notified. The unit cost of screening was <20 euros per individual screened.

Table 1.

Number of Symptomatic and Asymptomatic Individuals Affected by Microbiologically Confirmed or Not Confirmed Tuberculosis

	TB Bacteriologically Confirmed Cases	TB Bacteriologically Not Confirmed Cases	Total
Symptomatic individuals	8	4	12
Asymptomatic individuals	4	2	6
Total	12	6	18

Abbreviation: TB, tuberculosis.

These preliminary findings reveal a post-entry screening prevalence rate of 535 (95% confidence interval, 317–844) per 100000 individuals screened and a number needed to screen equal to 187. If we consider that the estimated prevalence rate in Italy is 6.7 per 100000 population [10], the prevalence found in migrants is 80 times greater. Furthermore, it is interesting to consider that this prevalence is even higher than the estimated TB prevalence in migrants’ home countries (Supplementary Table 1) [11].

The higher prevalence in our report compared to other authors’ findings in Europe [4, 5] may be explained by the different nature of migration flows reaching the Italian coasts with respect to the migrant populations arriving in northern European countries, in terms of different origin countries and different migration routes. Most of the screened migrants came from high-incidence countries and reached Italian coasts via the Mediterranean sea after spending several months in Libya, waiting for the transfer. Frequently they reported a history of detention and overcrowding under precarious living and social conditions that might increase the risk of TB transmission and the risk of progression from infection to disease. It is important to note, however, that despite the higher prevalence of TB among migrant populations, transmission from migrant groups to host country population is uncommon. As observed elsewhere [12], it is interesting to notice also that migrants without (or not reporting) symptoms can be affected by a transmissible form of TB: among the 12 individuals with bacteriologically confirmed TB, 33% (n = 4) did not report any TB-suggestive symptom.

A limitation of our study is that the data cover only a 1-year period; therefore, we could not yet evaluate temporal trends in the incidence of TB detected by our regional screening strategy.

However, our findings suggest that travel history by itself (length and conditions) might play an independent role in the risk of developing active TB and should be taken into account beside the estimated WHO TB incidence rate, which is often used as a demarcation line to decide if screening should be performed.

To our knowledge, this is the first report of TB screening using CXR in a migrant population implemented in Italy. Although no studies to compare the performance of different screening approaches in our country have been done yet, our data show the effectiveness of CXR screening in diagnosing patients with active TB who did not report symptoms and who would be missed by a symptom-based screening.

Based on our findings, it is clear that active TB screening with systematic CXR is well justified in Italy and should be continued. It will be essential to continue monitoring TB screening results and share other regional experiences to identify the most appropriate screening approach for early identification of TB among the migrant target group.

Supplementary Data

Supplementary materials are available at Clinical Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author.

Note

Potential conflicts of interest. All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.