The hookworms Necator americanus and Ancylostoma duodenale infect approximately 1 billion people worldwide. The prevalence of hookworm infection increases with age in children, typically reaching a plateau in late adolescence, whereas the intensity of infection may continue to increase throughout adulthood. Hookworms cause intestinal blood loss in amounts proportional to the number of adult worms in the gut. The relationship between hookworm infection intensity and hemoglobin concentration is evident in epidemiologic studies, but may be apparent only above a threshold worm burden that is related to the iron stores of the population. Current hookworm control efforts are focused on reducing infection load and transmission potential through periodic anthelmintic chemotherapy. Several controlled trials have demonstrated a positive impact of anthelmintic treatment on hemoglobin levels, with best results obtained in settings where iron intakes were also increased. Evidence suggests that anthelmintic programs will have modest impacts on iron deficiency anemia in the short term, with greater impacts on more severe anemia. Hookworms are an important cause of anemia in women, who are often overlooked by current helminth control programs. Current WHO recommendations for use of anthelminthics in schoolchildren and women are reviewed. There is a need to clarify whether hookworms are an important etiology of iron deficiency anemia in preschool children.

Hookworm Control as a Strategy to Prevent Iron Deficiency

Thalassemia: The consequences of unbalanced hemoglobin synthesis☆

Human schistosomiasis and anemia: the relationship and potential mechanisms.

The public health significance of hookworm disease is briefly reviewed. The latest evidence confirms that blood loss caused by the worms' feeding activity in the gut is a contributing factor in the development of poor iron status leading to iron-deficiency anaemia. The World Health Organization has identified adolescent girls and women of child-bearing age as high-risk groups regarding the impact of hookworm disease. The merits of treating pregnant women with anthelminthic drugs after the first trimester are discussed.

The public health importance of hookworm disease.

In the developing world, young women, pregnant women, and their infants and children frequently experience a cycle where undernutrition (macronutrient and micronutrient) and repeated infection, including parasitic infections, lead to adverse consequences that can continue from one generation to the next. Among parasitic infections, malaria and intestinal helminths coexist widely with micronutrient deficiencies and contribute importantly to anemia and this cycle of retarded growth and development. In somewhat more limited or focal geographic settings, other parasitic diseases (e.g., schistosomiasis, filariasis) contribute similarly to this cycle. It is undoubtedly much better to enter a pregnancy free of infection and nutritionally replete than the various alternatives. Existing intervention strategies for micronutrient support and for the control of common parasitic infections before or during pregnancy, particularly malaria and intestinal helminths, should be followed. However, further research to identify barriers and priority approaches to achieving this goal remain very important in resource-poor settings where targeted public health efforts are required.

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Pregnancy, nutrition and parasitic diseases.

Symptomatic, radiological, and functional improvement following treatment of urinary schistosomiasis in Egypt.

Summary
The blood and iron losses in 12 patients with Ancylostoma duodenale infection were measured with Cr51-tagged autogeneous red blood cells The daily blood loss ranged from 136 to 45 ml with a mean of 264 ml The daily iron loss ranged from 356 to 994 mg with a mean daily loss of 606 mg There was a definite correlation between the intensity of hookworm infection, the daily blood loss, and the severity of the anemia; there occurred a corresponding increase in the daily blood loss and the severity of anemia as the total worm load increased
The mean blood loss per day per A duodenale was 026 ml with a standard deviation of ±0045 ml The calculated mean daily blood loss per 1000 eggs per gram of feces was 447 ml with a standard deviation of ± 16 ml The Cr51 red cell half-life was markedly shortened in those patients with hemoglobin values under 65 g per 100 ml and did not return to normal after deworming and cessation of intestinal bleeding

Blood loss in pure ancylostoma duodenale infection in egyptian farmers.

The mean daily blood and iron losses in 7 patients with proved bilharzial colonic and rectal polypi were measured by the 51Cr-tagged red cell technique. The daily blood loss ranged from 7·5 to 25·9 ml. (mean 12·5 ml.) and the daily iron loss ranged from 0·6 to 6·7 mg. (mean 3·3 mg.). Surgical removal of a large polyp in one patient resulted in cessation of blood loss. In spite of continued blood loss, 3 patients with severe iron deficiency anaemia responded rapidly, clinically and haematogically, to oral iron treatment.

Blood loss in chronic Schistosoma mansoni infection in Egyptian farmers.

In 18 patients with Schistosoma haematobium infection the urinary blood loss was measured by labelling the red blood cells in vivo with 59Fe 9 of the 18 had recurrent severe haematuria with bright to dark red urine; the other 9 had occasional terminal haematuria and clear urine In those with severe haematuria the daily blood loss ranged from 2·6 to 126 ml, and the daily iron loss from 0·6 to 37·3 mg There was no calculated blood loss in the patients with occasional terminal haematuria and clear urine The severest iron-deficiency anaemia occurred in patients with obvious haematuria and combined S mansoni and A duodenale infections No relationship was found between the worm burden, estimated by the daily egg output by Bell's egg counting technique, and the amount of urinary blood loss Intravenous pyelography in 5 patients with severe haematuria revealed bilateral hydronephrosis and hydroureters with multiple bladder filling defects, and it is suggested that these schistosomal granulomatous lesions of the bladder may be the main source of bleeding

Urinary blood loss in Schistosoma haematobium infection in Egyptian farmers

In 12 patients with Ancylostoma duodenale infection the gastro-intestinal blood loss was measured before and after successful treatment with anthelmintic. The daily blood loss ranged from 2·32 to 120·30 ml., and the daily iron loss ranged from 0·33 to 13·0 mg. The mean daily blood loss per A. duodenale was 0·20 ± 0·055 ml. 5 of the 12 patients continued to have significant blood loss (over 2 ml. per day) after successful treatment of their hookworm infection. All 5 had active Schistosoma mansoni infection, and of these 5 patients 2 had, in addition, obvious bleeding bilharzial colonic and rectal polypi; 2 others had grossly enlarged bilharzial spleens, and oozing from oesophageal varices was suspected to have contributed to their daily blood loss.

A. R. Schulert

Papers

Symptomatic, radiological, and functional improvement following treatment of urinary schistosomiasis in Egypt.

Blood loss in pure ancylostoma duodenale infection in egyptian farmers.

Blood loss in chronic Schistosoma mansoni infection in Egyptian farmers.

Urinary blood loss in Schistosoma haematobium infection in Egyptian farmers

Blood loss in Egyptian farmers infected with Ancylostoma duodenale.