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The most common radiological finding in patients with chronic severe hookworm disease is a mild to moderate generalized cardiac enlargement, identified on chest radiographs (Figs. 12.14 and 12.15), due to the patients' profound anemia and hypoproteinemia. The cardiac silhouette is usually globular and it is difficult to evaluate the size of individual chambers. The cardiac shape may simulate a pericardial effusion, but the typical oligemic low-output state of the latter differs significantly from the plethoric pulmonary vasculature of the high-output hyperkinetic anemic state. There may be bulging of the pulmonary outflow tract; the pulmonary arteries and veins are more prominent and there is greater perfusion of the upper lobes in the erect position than is normally seen because of the high-output state and hypervolemia.

Congestive failure may be present, and small pleural effusions may develop owing to the hemodynamic state and hypoproteinemia accompanying hookworm disease; pulmonary edema is rarely noted. The cardiac changes are much more pronounced in children than in adults, and the reversion to a normal cardiac silhouette is also greater in children as their hemoglobin rises with treatment. The hyperknetic, hypervolemic circulation present in anemic patients can easily be overloaded by transfusion, producing right heart failure; the lungs remain free of edema but a small amount of pleural fluid may be present.

The development of a hyperplastic marrow may expand the medullary cavity of bones. The combination of anemia and, at times, an associated folic acid deficiency, contributes to a delay in skeletal maturation in children.

Differential Diagnosis

The differential diagnosis includes other parasitic infections, particularly giardiasis and strongyloidiasis, together with other causes of the malabsorption pattern.

Fig. 12.14 (A) Generalized cardiomegaly in a 7-year-old Nigerian child with hookworm anemia. The heart has a globular configuration. (B) There is an extraordinary change in size and shape of the heart over a 3 -week interval during which the hemoglobin level rose by 64%. (Reprinted from Cockshott and Middlemiss: Clinical Radiology in the Tropics, with permission of Churchill Livingstone Publishers).

Fig. 12.15 Chest radiographs of an adult with severe hookworm anemia obtained before and after elevation of the patient's hemoglobin level. (A) Initially there is moderate cardiomegaly and prominence of the main pulmonary artery. (B) After treatment considerable improvement is seen. (Reprinted from Cockshott and Middlemiss: Clinical Radiology in the Tropics, with permission of Churchill Livingstone Publishers).

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