Hookworm infection, a hallmark of poverty nowadays, is a disease mainly caused by Necator americanus and Ancylostoma duodenale, nematodes typically found in tropical and subtropical areas of Latin America, Asia, and sub-Saharan Africa. The disease may be asymptomatic, but affected individuals may be malnourished and anemic as a consequence of infection. Individual eradications may be achieved, but patients may become reinfected as a result of unsuitable living conditions. This condition is especially dangerous for pregnant women and may cause prematurity and low birth weight children due to maternal anemia or even hookworm infection in the newborn, as the parasite is excreted in the human colostrum and milk.
After infection, the first symptom patients notice is a palm or sole irritation, that is pruritic and either vesicular or erythematous, that should be differentiated from cutaneous larva migrans. As nematodes migrate to the lungs, cough, wheezing and exertion dyspnea appear; if symptoms are severe and accompanied by pleurisy, hemoptysis, and low fever, Löffler syndrome should be suspected [1]. On the other hand, hookworm infection can also lead to hypothermia, severe enough to lower fever caused by malaria [2].
Gastrointestinal infection leads to abdominal pain, nausea, diarrhea, flatulence and anorexia, that makes the iron deficit even more severe [3]. Some patients may have pica and ingest dirt, which puts them at further risk for infection and Wakana syndrome, characterized by and pharyngeal itching, hoarseness, nausea, vomiting, and cough [4]. Intestinal hookworms cause persistent blood loss, which might manifest as melena and cause anemia, which may trigger symptoms like a headache, palpitations, fatigue and impaired memory and learning capabilities. Eosinophilic enteritis causes severe abdominal pain that might lead to confusion with appendicitis or intestinal perforation.
Other symptoms include weight loss, impotence, joint and sternal pain and pain in the lower extremities [3] [5].
The skin might reflect the chronic character of the anemia, as it becomes wax-like and has green-yellow color, typical to tropical chlorosis. Dermatological examination shows the rash described above, that is sometimes accompanied by scratching lesions or typical cutaneous larva migrans, a serpiginous erythematous lesion that appears at the hookworm entrance site [6]. Lung auscultation reveals wheezing and stool inspection may diagnose melena. Signs of heart failure appear if anemia is severe. Patients might also present with peripheral edema or even anasarca, due to hypoproteinemia [7]. Infected children exhibit growth retardation [8].
Blood tests must include a complete cell blood count, that reveals an iron deficiency anemia and eosinophilia, more prominent in eosinophilic enteritis than larva migrans [7]. Serum immunoglobulin E is high, as in other parasite infections. Serum ferritin and protoporphyrin levels are decreased [9].
Stool evaluation may diagnose infestation by describing eggs or larvae, but may also be negative, in which case disease cannot be excluded. Stool should be processed immediately after emission and look especially for eggs because larvae might be confused with those of Strongyloides stercoralis.
Polymerase chain reaction is another valuable but unfortunately not widely available way to diagnose this disease [10].
Hookworm infection patient may also be susceptible to other diseases, due to the demonstrated down-regulation of the immune system that comes with this condition [11] [12].
Other diagnostic methods include colonoscopy, that describes ulceration and sometimes adult hookworms attached to the colon and thoracic radiography, that might show diffuse infiltrates.