Iron deficiency
Iron deficiency is the most common nutritional deficiency globally, estimated to affect half the children living in developing countries. High-risk groups include infants and young children during periods of rapid growth (especially between 6 and 24 months of age) and women of childbearing age. Infants and young children are also at increased risk if they continue to breastfeed after 6 months of age without iron supplementation , or if they consume weaning foods low in iron content.
Iron-deficiency anemia typically results from inadequate bioavailable dietary iron. This condition is more common among groups with a history of infrequent consumption of animal sources of iron, and also results from the presence of dietary inhibitors of iron absorption, such as tannins (e.g. tea) and phytates from certain plants. Non-dietary factors associated with anemia include parasitic infections such as intestinal parasites, particularly hookworm and malaria infection (both clinical and subclinical), hemoglobinopathies such as sickle cell trait/disease, thalassemias, and chronic infections. Thalassemias are more prevalent in certain parts of the world, including Southeast Asia, India, the Middle East, Eastern Europe, and Africa. In addition, other micronutrients deficiencies (e.g., vitamin B12, folate, and vitamin A) may also cause or contribute to anemia. Vitamin B12 and folate are classically associated with a megaloblastic anemia.
Moderate to severe iron deficiency leads to anemia which can have long-term impact, particularly among children. Chronic iron deficiency is associated with impaired psychomotor and mental development among infants and cognitive impairment in adolescents. Iron deficiency has also been linked to negative infant social-emotional behavior. In adults, anemia is associated with fatigue, low productivity at work, and may result in impairment of reproductive functions.
Anemia is particularly prevalent among refugee children. Studies of children in refugee camps from Syria, Jordan, the West Bank, the Gaza strip, Lebanon, and Thailand (Burmese) reported overall anemia prevalence rates ranging from 54% to 85%. Although dietary iron deficiency is the most common condition associated with anemia, refugees frequently have multiple etiologies contributing to this condition. Almost half (48%) of Burundian refugee children living in a Tanzanian refugee camp where malaria and hookworm prevalence rates were high had severe anemia, defined as a mean Hb level below 80.0 g/L. A study of Burmese refugee children found 10% to be severely anemic by this same standard.
The CDC and World Health Organization (WHO) consensus statement on best measures of iron status reiterate the challenge in finding an affordable, field-friendly method for measuring iron deficiency that is more sensitive than hemoglobin levels and indices. Although a complete discussion of anemia is beyond the scope of this section, other common etiologies and initial evaluation are addressed in the General Section of the Domestic Refugee Medical Screening Guidelines. Given the potential long-term effects of iron deficiency anemia on cognitive function and productivity, screening, treatment, and prevention are of particular importance.
Vitamin D deficiency
High rates of vitamin D deficiency have been reported in both resource-rich as well as resource-limited countries, placing both children and adults at risk of complications (e.g., rickets and osteoporosis, respectively).
Although inadequate dietary intake of vitamin D and calcium, as well as inadequate sources of dietary iron, may contribute to vitamin D deficiency in resource-limited settings, most vitamin D is derived from non-dietary sources. Therefore, the etiology of vitamin D deficiency is multifactorial and heavily dependent on non-dietary determinants such as limited sun exposure (protective or religious clothing, moving to temperate climates, and the tradition of keeping infants indoors), increased skin pigmentation , reduced in-utero exposure , and reduced capacity to synthesize vitamin D with increasing age. Consequently, those at particularly high risk are persons with dark skin, those who cover most of their skin when outdoors, infants with history of prolonged breastfeeding without supplements, infants whose mothers are vitamin D deficient, pregnant and lactating women, those living in temperate regions, those with chronic malabsorptive states such as celiac disease, and the elderly. These factors converge for several refugee groups, placing them at particular risk, so that vitamin D deficiency among veiled, dark-skinned immigrant women has been reported to be as high as 80% , although most immigrant groups appear to be affected by vitamin D deficiency.
Others micronutrient deficiencies
Micronutrient deficiencies are well documented in many populations in resource-limited settings where refugees originate. A few studies have noted refugees to be at risk for less common micronutrient deficiencies due to the tenuous dietary intake of families just prior to entering refugee camps, a dependence on grain-based external food aid, and reduced access to traditional sources of diversified foods. However, little is known about the prevalence or impact of these deficiencies on migrating refugees prior to and after arrival in the United States. The clinician should be aware of common deficiencies as well as their characteristic findings, since these may be encountered during the new refugee arrival medical evaluation.
Vitamin A
While vitamin A deficiency is seldom encountered in industrialized countries, it is a common nutritional deficiency in the developing world. Vitamin A deficiency is the leading cause of preventable blindness among children in the world with 500,000 children losing their vision annually, and approximately half of these children dying within a year of losing their sight.
Vitamin A deficiency produces a spectrum of vision and ocular changes ranging from poor night vision and Bitot spots (areas of abnormal squamous cell proliferation and keratinization of the conjunctiva), progressing to more severe ocular forms of xerophthalmia, keratomalacia, corneal perforation, and, in its most severe form, permanent blindness. In addition, vitamin A deficiency leads to impaired bone growth, dry skin and hair, and impaired humoral and cell-mediated immune response in turn increasing the risk for infections.
Although there is an established policy in refugee camps for vitamin A supplementation and increasingly for vitamin A fortification, several studies have demonstrated high rates of vitamin A deficiency among refugees, particularly among children , but there is little report of vitamin A deficiency among refugees resettled in developed countries.
Zinc
While zinc deficiency is widespread, those at greatest risk are concentrated in areas of the world consuming plant-based diets. Zinc is required for the catalytic activity of over 100 enzymes and plays an important role supporting growth and development during pregnancy, childhood, and adolescence. Zinc deficiency is characterized by growth retardation, loss of appetite, and impaired immune function. In more severe cases it may cause hair loss, diarrhea, delayed sexual maturation, impotence, and, in males, hypogonadism. Weight loss, delayed healing of wounds, eye and skin lesions, taste abnormalities and lethargy may also occur.
B12
The global prevalence of vitamin B12 deficiency is uncertain due the lack of nationally representative data. Vitamin B12 occurs naturally in animal products (e.g., eggs, meat, milk), and its deficiency results from decreased dietary intake as well as impaired absorption (e.g., intrinsic factor deficiency), and malabsorption (e.g., chronic gastritis from Helicobacter pylori, bacterial overgrowth). Although commonly asymptomatic, several nonspecific symptoms, such as fatigue, decreased mental work capacity, decreased concentration and memory, irritability, depression and other psychiatric symptoms, have been associated with B12 deficiency. Neurologic signs and symptoms may develop with the earliest signs being diminished vibratory sensation and proprioception. Other signs and symptoms include weakness, numbness or tingling of the extremities, impaired sense of smell, loss of coordination and ataxic gait, and, in severe cases, subacute combined degeneration of the spinal cord.
Bhutanese refugees have been documented to be at particular risk of B12 deficiency with rates as high as 64% among overseas refugees and 27% of postarrival medical screenings.
Classically vitamin B12 deficiency is associated with macrocytic red cells with or without anemia, presence of hypersegmented neutrophils, and occasionally pancytopenia.
B3/Niacin and tryptophan
Pellagra is the deficiency of niacin and/or tryptophan, usually in combination with lack of other amino acids and micronutrients. Inadequate intake of either niacin or tryptophan is most common in areas where corn is the primary constituent of the diet. In addition, pellagra occurs in areas of South Asia where people eat millet with a high leucine content, which may contribute to pellagra. Secondary deficiency may occur due to diarrhea, cirrhosis, or alcoholism.
Advanced pellagra may cause a symmetric photosensitive dermatitis (e.g., “Casal’s necklace, butterfly-shaped rash on the face, “glove-like rash”), diarrhea, stomatitis, and neurologic symptoms including anxiety, tremors, and peripheral neuritis. The classic symptoms of pellagra are generally not well observed in infants and children, although anorexia, irritability, anxiety and apathy have been observed.
Outbreaks have been reported among refugees dependent upon external food supplies through the years, often precipitated by changes in the diversity and quality of food rations. Although sporadic cases are known to be detected in newly arriving refugees there are no published data in of the prevalence of this disorder in refugees resettled to the United States.
Iodine
Iodine deficiency is estimated to affect 2 billion individuals worldwide, including an approximately 31.5% of school-aged children, and is the world’s most prevalent cause of thyroid disease. Iodine, a trace element found in soil and seafood, is an essential component of the thyroid hormones involved in regulating the body’s metabolic processes. Deficiency disorders include physical and mental retardation (including severe congenital form known as cretinism), hypothyroidism, goiter, and varying degrees of other growth and developmental abnormalities.
The universal salt iodization has been an effective approach to reducing the burden of iodine deficiency disorders. However, reports of excessively high levels of iodine have been reported among refugee camps in Africa raising a concern for a risk for iodine-induced hyperthyroidism (IIH). IIH can occur among previously iodine deficient populations, particularly females over 40 years of age, during a short period following the introduction of iodized salt. While this risk for IIH remains, there are currently no reports of its occurrence among resettled refugees.
Thiamine/B1 deficiency
Thiamine, or vitamin B1, plays an important role in energy metabolism and building of tissues. Low levels may result from poor intake (e.g. associated with diets heavily consisting of white or milled rice, or heavy alcohol intake combined with poor food intake), altered metabolism (e.g. fever, pregnancy, breastfeeding, chronic liver disease, hyperthyroidism), from losses (e.g. extended diarrhea), or rarely, by the intake of food that contain thiaminases or antithiamine compounds.
Thiamine deficiency may result in the condition termed beriberi, that is associated with a spectrum of symptoms, including loss of appetite, constipation, fatigue, irritability, memory loss, peripheral neuropathy, muscle weakness and pain, areflexia, foot drop (“dropsy”), tachycardia, and heart failure. In adults, beriberi is grouped into two main syndromes. Wet, or edematous, beriberi is characterized by cardiac failure and, although a chronic disease, may have an acute presentation. Dry beriberi is multifocal peripheral and/or central nervous system dysfunction, which includes Wernicke encephalopathy and Korsakoff syndrome.
Several outbreaks of thiamine deficiency have been documented among refugees in camps, although there is little evidence of significant deficiencies among refugees after resettlement.
Vitamin C deficiency
Vitamin C deficiency (ascorbic acid) has been estimated to occur in 14% of males and 10% of females in the United States with individuals most at risk being those with chronic malnutrition, alcoholism, and restrictive diets devoid of fruit and vegetables.
The clinical signs and symptoms of vitamin C deficiency, also known as scurvy, are manifest due to impaired collagen synthesis, and include ecchymoses, petechiae, bleeding gums, hyperkeratosis, and impaired wound healing. Other systemic symptoms include weakness, malaise, joint pain and swelling, edema, depression, and neuropathy.
Outbreaks of scurvy have been reported in refugee camps located in Somalia, Bhutanese refugees in Nepal, Ethiopia, Kenya, Somalia, and Sudan. There are no published data of vitamin C deficiency in refugees resettled to the United States.