Tuberculosis in Tropical Areas and Immigrants

Abstract

About 95% of cases and 98% of deaths due to tuberculosis (TB) occur in tropical countries while, in temperate low incidence countries, a disproportionate portion of TB cases is diagnosed in immigrants.Urbanization, poverty, poor housing conditions and ventilation, poor nutritional status, low education level, the HIV co-epidemic, the growing impact of chronic conditions such as diabetes are the main determinants of the current TB epidemiology in tropical areas. TB care in these contests is complicated by several barriers such as geographical accessibility, educational, cultural, sociopsychological and gender issues. High quality microbiological and radiological facilities are not widely available, and erratic supply of anti-TB drugs may affect tropical areas from time to time. Nevertheless in recent years, TB control programs reached major achievements in tropical countries as demonstrated by several indicators.Migrants have a high risk of acquire TB before migration. Moreover, after migration, they are exposed to additional risk factors for acquiring or reactivating TB infection, such as poverty, stressful living conditions, social inequalities, overcrowded housing, malnutrition, substance abuse, and limited access to health care. TB mass screening programs for migrants have been implemented in low endemic countries but present several limitations. Screening programs should not represent a stand-alone intervention, but a component of a wider approach integrated with other healthcare activities to ensure the health of migrants.

The Impact of Tuberculosis among Immigrants: Epidemiology and Strategies of Control in High-Income Countries—Current Data and Literature Review

“…In this setting, phenotypic drug-susceptibility testing (DST) on cultured specimens is the conventional method used to detect resistance to first-and SLD-TB drugs in MDR-TB and monitoring patients' response to treatment [4]. Finally, the challenge of TB diagnosis in the low-income countries including the tropics, must also take into account the differential diagnosis with a wide spectrum of microbial agents causing respiratory infections of which migrants can be affected and include viruses, bacteria (Actynomicetes), and parasites (paracoccidioidomycosis, paragonimiasis, dirofilariosis), which can mimic TB [2,3,9], and other diseases such as sarcoidosis and cancer. In these settings, basic radiography and other analyses are of considerable use but are not available in all centers [9].…”

“…To test immigrant and refugee children with LTBI who are probably vaccinated with BCG, IGRAs may limit the number of children targeted for preventive therapy [48]. The use of one-step IGRA has also demonstrated to be the best option for young migrants [9]. Although in the last decade, IGRAs have increasingly replaced the use of TST, these tests have also limitations, both cannot verify the presence/ absence of dormant bacteria still able to reactivate and thus they do not reliably predict who will progress to active TB [2,3].…”

“…Overview and epidemiological features of TB among immigrants in low-TB burden countries and screening practices 2.1. Overview and epidemiological features of TB among immigrants in low-TB burden countries 1 Many 1 migrants originating from countries where TB has a high incidence, including tropical areas [9], have a high risk of acquiring TB before migration. Much of TB burden is concentrated in high-burden settings of Africa and Asia (28 and 58%, respectively) where TB continues to be a cause of morbidity and mortality [5].…”

“…Some areas of tropical countries, such as Haiti, Perù, Bolivia, and Suriname, have the highest TB incidence in the Americas (between 100 and 200 per 100,000 inhabitants) [10], whereas Brazil has a high TB burden, but this is not uniformly distributed. In sub-Saharan Africa and in some regions of India, HIV-coinfection and poverty affecting housing conditions, ventilation, nutritional status, education, and access to health care, other than growing urbanization with the consequent overcrowded living conditions, are the most important determinants of TB epidemic in tropical countries [9].…”

“…In the European Economic Area (EEA), the majority of subjects of foreign origin with TB in 2009 originated from Asia, Africa, and other European countries (34, 28, and 9.5%, respectively) [9,10,12]. This proportion continues to increase, and represents an important cause of the overall resurgence of the TB epidemic in the USA and Western Europe (EU) [12].…”