Screening of Imported Infectious Diseases Among Asymptomatic Sub-Saharan African and Latin American Immigrants: A Public Health Challenge

Abstract

Abstract. Migrants from developing countries are usually young and healthy but several studies report they may harbor asymptomatic infections for prolonged periods. Prevalence of infections were determined for asymptomatic immigrants from Latin America and sub-Saharan Africa who ettended to a European Tropical Medicine Referral Center from 2000 to 2009. A systematic screening protocol for selected infections was used. Data from 317 sub-Saharan Africans and 383 Latin Americans were analyzed. Patients were mostly young (mean age 29 years); there were significantly more males among sub-Saharan Africans (83% versus 31.6%) and pre-consultation period was longer for Latin Americans (5 versus 42 months). Diagnoses of human immunodeficiency virus (HIV), chronic hepatitis B and C virus infection, and latent tuberculosis were significantly more frequent in sub-Saharan Africans (2.3% versus 0.3%; 14% versus 1.6%; 1.3 versus 0%; 71% versus 32.1%). There were no significant differences in prevalence for syphilis and intestinal parasites. Malaria and schistosomiasis prevalence in sub-Saharan Africans was 4.6% and 5.9%, respectively, and prevalence of Chagas disease in Latin Americans was 48.5%. Identifying and treating asymptomatic imported infectious diseases may have an impact both for the individual concerned and for public health. Based on these results, a systematic screening protocol for asymptomatic immigrants is proposed.

Infectious Diseases in Sub-Saharan Immigrants to Spain

“…The prevalence of LTBI (61%) in this study was similar to that of other studies (46-71%), being higher than the general prevalence in the world (onethird of the world's population is estimated to be infected) and in that of other immigrant groups. [7][8][9][10]12,34 Nonetheless, the prevalence of LTBI in this study may be overestimated, since false-positive TST result may be observed in subjects who have received the Bacillus Calmette-Guérin vaccine or are infected with other mycobacterias. 12 This is important to take into account because the side effects of chemoprophylaxis for LTBI are not negligible.…”

“…7,10,38 On the other hand, some studies have reported lower prevalences (3-11%) than what we found, which may be explained by different reasons: experience and type of laboratory test used for the diagnosis, the difficulties to complete screening protocols in this population, the short time of arrival to Spain in our population, the area of origin, and different migratory processes. 8,9 Helminths were present in 28% of our cases. Previous studies in immigrants have described lower prevalences of helminths (6-16%), showing a trend to being higher in studies in which most cases were from sub-Saharan Africa.…”

“…In this study, the prevalence of HBsAg in sub-Saharan immigrants (15%) was similar to that described in other studies (10-19%), being higher compared with other immigrant groups. [7][8][9][10]38 International guidelines recommend screening in populations in which the prevalence is estimated to be greater than 2%. 39 On the other hand, although the prevalence of HbsAg in sub-Saharan immigrants remains as high as 10% in some areas in Africa, it has decreased in recent years probably due to expanded immunization programs in these countries.…”

“…6 In fact, the prevalence of some of these infections has been estimated to be particularly high among sub-Saharan immigrants, especially among the more vulnerable cases requiring social help. 4,7,8 Several studies have described a higher prevalence of latent tuberculosis infection (LTBI) (46-71%) and positive hepatitis B surface antigen (HBsAg; 10-14%) in sub-Saharan immigrants than in Latin American (LTBI, 19-47%; HBsAg, 0-7%) or Asian immigrants (LTBI, 30-51%; HBsAg, 0-3%). [7][8][9][10][11] Coinfections should also be taken into account as some of these infections have a similar geographical distribution.…”

“…4,7,8 Several studies have described a higher prevalence of latent tuberculosis infection (LTBI) (46-71%) and positive hepatitis B surface antigen (HBsAg; 10-14%) in sub-Saharan immigrants than in Latin American (LTBI, 19-47%; HBsAg, 0-7%) or Asian immigrants (LTBI, 30-51%; HBsAg, 0-3%). [7][8][9][10][11] Coinfections should also be taken into account as some of these infections have a similar geographical distribution. Prompt diagnosis and treatment of these infections are important, since, for example, in the case of LTBI, 5-10% of cases may develop active tuberculosis (TB), and a quarter of the cases with HBsAg may develop cirrhosis and/or liver cancer.…”