In 1800, the population of the island of Sri Lanka was approximately 1.2 million. This figure would begin to grow following the island’s complete annexation into the British Empire with the end of the Second Kandyan War in 1815. Population growth then increased much faster towards the end of the 19th century, as child mortality rates dropped and large numbers of Indian migrants were imported to work on British plantations. These migrants were largely Tamil migrants from southern India, and by 1911, this group would make up almost 13 percent of the island’s population (on top of the existing 13 percent Sri Lankan Tamil population).

Population growth would expand rapidly in the years immediately following the island’s independence from the British Empire in 1948. However, this growth would slow in the 1950s, as legislation passed by the Sinhalese-dominated government immediately following independence resulted in the removal of citizenship for an estimated 700,000 Indian Tamils, and the deportation of over 300,000 to India over the following three decades. Growth would slow even further after the ethnic clashes of Black July in 1983, which marked the beginning of a civil war in Sri Lanka which would last from 1983 to 2009 and result in the death of over 80,000 people, and the displacement of an estimated 800,000. However, since the end of the civil war in 2009, the population of Sri Lanka has continued to grow, and in 2020, the population of Sri Lanka is estimated to be over 21 million.

BackgroundIron deficiency, the most common micronutrient disorder and cause of anaemia globally, impairs growth, cognition, behaviour and resistance to infection.Methods/ResultsAs part of a national survey of inherited haemoglobin variants in 7526 students from 72 secondary schools purposefully selected from the 25 districts of Sri Lanka, we studied 5912 students with a normal haemoglobin genotype. Median age was 16.0 (IQR 15.0–17.0) years and 3189 (53.9%) students were males. Most students were Sinhalese (65.7%), with fewer Tamils (23.1%) and Muslims (11.2%). Anaemia occurred in 470 students and was more common in females (11.1%) than males (5.6%). Haemoglobin, serum ferritin, transferrin receptor and iron were determined in 1196 students with low red cell indices and a structured sample of those with normal red cell indices (n = 513). The findings were weighted to estimate the frequencies of iron deficiency and iron deficiency anaemia classified according to WHO criteria. Iron depletion (serum ferritin <15ug/ml) occurred in 19.2% and cellular iron deficiency (low serum ferritin and transferrin receptor >28.1 nmol/l) in 11.6% students. Iron deficiency anaemia (cellular iron deficiency with low haemoglobin) occurred in only 130/2794 (4.6%) females and 28/2789 (1.0%) males. Iron biomarkers were normal in 83/470 (14.6%) students with anaemia. In multiple regression analysis, the odds for iron depletion and cellular iron deficiency were about one-third in males compared with females, and the odds for iron deficiency anaemia were about one fifth in males compared to females. Tamil ethnicity and age <16 years increased the risk of all three stages of iron deficiency and living at high altitude significantly reduced the risk of iron depletion.ConclusionsLow iron status and anaemia remain common problems in Sri Lankan secondary school students especially females, younger students and the socioeconomically disadvantaged Tamil population. More research is needed to identify factors other than low iron status that contribute to anaemia in adolescents.

GTM projection, test set 5: Sri Lankan Tamil from the UK (STU). Projection of Sri Lankan Tamil from the UK (black points) onto a GTM map trained with 10 principal components. File name: 1000G_GTM_projection_STU.html. The file can be viewed in a web browser with internet access. (HTML 482 kb)