Hookworm as an overlooked cause of overt gastrointestinal bleeding: A case report

Introduction

Hookworms are common parasitic organisms found in tropical countries. This infection is more prevalent in areas with inadequate water supply and poor sanitary conditions. ¹ Human beings are usually infected by two species of the worm, namely the Ancylostoma and Necator genera. ² Hookworm causes a plethora of symptoms, including abdominal pain, fatigue, anaemia, diarrhoea, malnutrition, lower respiratory tract infection (in the form of eosinophilic pneumonia), and itchy skin rashes, collectively referred to as helminthiases. ³ However, in some situations, when the worm burden is very high, it may cause upper gastrointestinal bleeding leading to haematemesis or melaena. The worm can cause considerable destruction of the intestinal epithelial lining, thereby leading to blood loss. ⁴

Case report

A 35-year old farmer presented as an emergency with complaints of multiple episodes of black stools for the previous two weeks, associated with easy fatiguability and lassitude. There was no history of haematemesis. He was, however, known to have a chronic inflammatory demyelinating polyneuropathy, under treatment with Azathioprine (though previously treated with steroids). He had no history of alcoholism nor pre-existing liver disorders. He also had no history of use of non-steroidal anti-inflammatory drugs.

On examination, he was pale with a tachycardia (110 beats/min). His sensorium and vital signs were within normal limits. Increased bowel sounds were heard without any organomegaly detected.

Laboratory investigations showed an anaemia (Hb 59 g/L), leucocytosis (16.4 × 10⁹/L) with eosinophilic predominance (18.3%). The platelet count was normal. Thyroid and renal functions were also normal. Liver function tests revealed low levels of serum total protein (61.2g/l) as well as low levels of serum albumin (2.97 g/l). A peripheral blood film revealed mild anisocytosis with a predominantly normocytic normochromic picture; the reticulocyte count was increased (3.5% of red blood cells) but with normal serum iron and ferritin values. Routine examination of stool, not stained by bile, showed the presence of hookworm ova. An abdominal ultrasound study was normal.

Packed red blood cell transfusions were given as well as intravenous proton pump inhibitor infusion and fluids. Later, an upper gastrointestinal endoscopy showed the presence of multiple hookworms in the first and second parts of the duodenum, besides the existence of antral and duodenal erosions (Fig. 1). He was subsequently treated with albendazole. As he did not experience any new episodes of bleeding from the gastrointestinal tract, he was discharged after a week in a haemodynamically stable condition with oral proton pump inhibitors.

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Figure 1.

Endoscopy showing the presence of hookworms in the duodenum.

Repeat upper gastrointestinal endoscopy done six weeks after discharge was absolutely normal. There had been no further episodes of visible gastrointestinal blood loss. Laboratory results showed a much improved haemoglobin level of 108 g/L, a normal total leucocyte count (8.8 × 10⁹/L) and normal platelet counts (1.9 × 10¹¹/L). Repeat serum iron profile parameter values were within normal limits.

Discussion

There are numerous common causes of upper gastrointestinal bleeding. Hookworm infestation is, however, a very infrequent cause of melaena. Hookworms are very common among tropical farmers due to their unhygienic working environment.^5,6 Infections usually manifest with non-specific abdominal pain and chronic anaemia; rarely do patients exhibit evident blood loss. The third-stage rhabditiform larva is the infective form, and enters the body by skin penetration by virtue of proteolytic substances. These third-stage larvae are then carried by the blood to the alveoli, from where they are coughed out in sputum, which is then swallowed. In the proximal parts of the small intestine, these larvae develop into adult forms (after two cycles of moulting) and then attach themselves to the intestinal wall, resulting in damage to its vasculature, thereby causing gastrointestinal bleeding. ⁷

The major amount of blood loss occurs from and around the site of adhesion of the worm in the intestine. However, it continuously switches its site of adsorption and also secretes a variety of chemical substances having anticoagulant properties (viz. Ancylostoma ceylanicum anticoagulant peptide-1).^8. Consequent iron insufficiency arises, specifically where a large worm burden exists in malnourished persons. Protein loss may also occur, leading to hypoalbuminaemia, which can subsequently cause generalised oedema and a deteriorating malnutrition status. ⁹

Microscopic examination of the stool sample is the backbone for diagnosing hookworm infection by identifying the ova present in the sample, although their eggs cannot be visualised from the stool sample in every case. ¹⁰ Then, repeated stool examination has a greater probability of diagnosing the parasitic infestation.

Upper gastrointestinal and capsule endoscopy techniques have been recently used in some cases for diagnosing hookworm infestation successfully. ¹¹ An increased eosinophil count is an important clue for the presence of parasites. These reach their highest level during the maturation of the larval forms into adult ones in the human gut. ¹² The production of various cytokines, such as interleukin-4 and -5, is responsible for the raised eosinophil counts. ¹³ The benzimidazole group of drugs (viz. Albendazole and Mebendazole) are the preferred anti-helminthic drugs, which have a cidal action against the adult parasite through inhibitory effects on multiple steps of cell division. ¹⁴