Tuberculosis transmission patterns among Spanish-born and foreign-born populations in the city of Barcelona

Abstract

During a 2-year period (2003-2004), tuberculosis (TB) transmission in Barcelona and the factors related to transmission among the Spanish- and foreign-born populations were studied by molecular epidemiology. Data were obtained from TB cases and Conventional Contact Tracing registries and genotyping was performed using restriction fragment length polymorphism (RFLP)-IS6110 and MIRU12 as a secondary typing method. Of the 892 TB cases reported, 583 (65.3%) corresponded to Spanish-born and 309 (34.6%) to foreign-born. Six hundred and eighty-seven cases (77%) were confirmed by culture. RFLP typing of 463/687 (67.4%) isolates was performed, revealing 280 (60.5%) unique and 183 (39.5%) shared patterns, which were grouped into 65 clusters. Spanish-born individuals were significantly more clustered than foreign-born individuals (44.6% vs. 28.8%; p 0.016). Clustering in foreign-born individuals was associated with HIV (p 0.051, odds ratio = 3.1, 95% confidence interval 1-10.9) and alcohol abuse (p 0.022), whereas, in the Spanish-born individuals, clustering was associated with age in the range 21-50 years, (p 0.024). Of the total clusters, 36/65 (55.3%) included only Spanish-born patients, whereas 22/65 (33.8%) included individuals from both populations. In mixed clusters, the index case was Spanish-born in 53% and foreign-born in 47%. Among the foreign-born, 2.8% were ill on arrival, 30% developed TB within the first year and 50.3% developed TB within the first 2 years; 58.3% were from South America. In conclusion, half of the foreign-born TB patients developed the disease during the first 2 years after arrival, which, in most cases, was the result of endogenous reactivation. Recent TB transmission among Spanish-born and foreign-born populations, as well as bidirectional transmission between communities, contributed significantly to the burden of TB in Barcelona, suggesting the need to improve Public Health interventions in both populations.

Impact of Immigration on the Molecular Epidemiology of Tuberculosis in Rhode Island

“…Moreover, the tendency of TB transmission exclusively within specific subgroups is more pronounced in recent immigrants, as suggested by their predominant membership to clusters of foreign-born patients only. A similar trend was observed in other studies and is probably due to the fact that new arrivals are more likely to live with other foreign-born persons in their own ethnic communities (4,41). In the foreign-born population of Rhode Island, people originating from Central America, the Caribbean, and Southeast Asia seem to be the most involved in local transmission chains.…”

Tuberculosis in Migrant Populations. A Systematic Review of the Qualitative Literature

“…In low-incidence countries, the rate of infection amongst foreign-born migrants reaches ten or twenty times that of the autochthonous population, and represents 60% to 70% of the recorded cases. Nonetheless, infection rates vary within the immigrant and non-immigrant population: although various studies report low infection rates in the non-immigrant population [5] and that transmission outside of small closed community or nuclear families is exceptional, some recent research highlights possible instances of transmission between distinct population groups [6–8]. The risk of transmission within the immigrant communities in the host country is however without question.…”

Methodological and Clinical Aspects of the Molecular Epidemiology of Mycobacterium tuberculosis and Other Mycobacteria

“…One study in Denmark actually estimated that infection of a migrant by a native Dane was up to 2.5 times more frequent than vice versa (448). The percentage of all clusters that consist of both natives and immigrants has also been used as a measure of transmission permeability; this amounted to 24% of all clusters in San Francisco (449); 29% in Almeria, Spain (450); 34% in Barcelona, Spain (451); and 36% in a recent study in Israel (452). The difference in transmission permeability between settings is well illustrated by a study in the Eastern Province of Saudi Arabia, where 25/33 (76%) clusters of 532 culture-confirmed TB cases occurring in a 2-year period were mixed autochthonous/ immigrant clusters (453).…”