Guidelines in pathology induced by Anisakis Original Article

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J. Domínguez Ortega, et al INTRODUCTION Anisakiasis -or anisakidosis- represents the infestation of man by the third larval development stage of the parasite Anisakis simplex. The high rate of fish consumption in Spain and the rather high frequency of its consumption as raw or undercooked preparations leads us to presume that the incidence of disease conditions associated to contact with the Anisakis simplex parasite is greater than the one reported up to now. A better knowledge of the clinical forms of these conditions on the side of the physician, and particularly so on the side of the Allergologist, is a sine qua non requisite for their correct diagnosis. The present concise guidelines aim at serving as a basis for a better approach to these diseases. The following general outline may be considered at the time of approaching the diagnosis of the disease and the ensuing therapeutic intervention: 1. Anamnesis 2. Initial complementary studies a) Plain radiographies b) Ultrasonography c) Endoscopic procedures 3. Anatomopathological study 4. Immunoallergic study a) Skin prick tests b) Quantitation of the serum total IgE and specific Anisakis simplex IgE levels c) IgE immunoblot d) Challenge tests ANAMNESIS A correct anamnesis is indispensable for a correct diagnosis of the disease. A history of ingestion of raw or undercooked cephalopods or fish (salted, smoked, marinated, or insufficiently cooked in a microwave oven 1 ) up to 48-72 hours before the onset of symptoms is highly orientative. Although a large number of potentially infested species exist, as demonstrated by Sanmartín et al. in 18 of 23 species of fish from the Galician coast studied 2 , anchovies, which are frequently consumed raw (marinated in vinegar), and squid among the cephalopods, are frequently implicated. However, in each geographic area a seasonal cycle appears to exist in which the infestation of fish is more frequent. 268 1600 1400 1200 1000 800 600 400 200 0 IgE IgE esp Specific IgE 1 mes moth 3 meses moth 6 meses moth Fig. 1. Evolution of the serum total and specific anti-Anisakis simplex IgE. The graph reproduces the variations in the total and specific Anisakis simplex IgE levels (mean values from a series of 12 patients with intestinal anisakiasis assessed at our Service) after one, three and six months of a strict fish-free diet. A good organ, system and apparatus anamnesis should be recorded, as there are several different clinical pictures that may be encountered. Among the gastrointestinal forms, the following ones should be borne in mind: The luminal form is the one in which there is only adherence of the parasite to the digestive mucosa; this form is asymptomatic, and the larvae may be detected in the faeces or the vomit. The gastric form features epigastric pain, nausea and occasionally vomiting. Cutaneous symptoms may also occur in association to the gastric manifestations 3 . The symptoms usually begin 24 to 48 hours after the ingestion. The intestinal form mimics acute appendicitis, diverticulitis or ileitis. This form features abdominal pain and changes in the intestinal rhythm resembling an obstructive episode 4-6 (due to the fact that in the affected area the intestinal wall is covered by a fibrinous exsudate and thickened by oedema). The ability to produce a number of proteases (aminopeptidase, trypsine-like protease and several hyaluronidases) that may attack and degrade macromolecules and thus favour penetration enables the parasite larva to perforate the gastrointestinal mucosa. It is thus even possible to find true intestinal wall perforation leading to peritoneal manifestations 7 . Extraintestinal forms (hepatic, splenic and pulmonary) have been reported as well as totally extradigestive ones (articular involvement, one case of asthma 8 and one of occupational conjunctivitis due to Anisakis sensitisation in a fishmonger 9 ). There is a group of patients who report cutaneous and systemic reactions after the ingestion of fish but tolerate such ingestion at other times. These patients have been included in the condition traditionally termed "Anisakis allergy". Although the most frequent manifestation is urticaria, angioedema and even anaphylactic shock have also
Fig. 2. Plain film of the abdomen in bipedestation. Air-fluid levels and dilated intestinal loops can be seen. been reported. In some cases, the cutaneous or anaphylactic symptoms are associated to the digestive ones 10 . LABORATORY DETERMINATIONS As in many other disease conditions coursing with an acute abdomen, the white blood cell differential count, although it may on occasion show no changes, may evidence a more or less marked leukocytosis with slight or moderate neutrophilia or eosinophilia; a later increase of the eosinophil count may be observed starting 24 hours after the onset of the clinical symptoms. The blood biochemistry is usually unremarkable unless complications of the intestinal pseudo-obstruction itself occur (repeated vomiting, etc.). Although at present not routinely measured, the serum Eosinophil Cationic Protein (ECP) levels seem to be consistently and markedly increased in this first phase, indicating Guidelines for Anisakis-induced disease a marked eosinophil activation and orienting the diagnostic process towards an eosinophilic inflammatory infiltrate. RADIOLOGY The gastric forms evidence no recognised radiological pattern. In the intestinal forms, the conventional radiology (plain films of the abdomen) shows a pseudo-obstruction pattern, with dilated small intestinal loops and air-fluid levels in the lateral decubitus or bipedestation projections (Fig. 2). The use of contrast media for imaging does not represent a first choice, although images of wall thickening, intestinal lumen narrowing with pseudotumour images, "fingerprint" signs and, very rarely, radiolucent lineal areas corresponding to the larvae may be seen. In the ultrasonography, which is the imaging technique of first choice in these cases, there is thickening of the intestinal wall, free peritoneal fluid in variable quantities, narrowing of the intestinal lumen and diminished peristaltism 11 . ENDOSCOPY AND ANATOMOPATHOLOGICAL STUDIES The certainty diagnosis is provided by the visualisation of the larva or larvae at gastroendoscopy or colonoscopy; these procedures also allow the larvae to be removed and resolution of the clinical condition ensues. Moderate to severe mucosal oedema may be observed in the first two days after infestation by the parasite, the severity of the clinical symptoms and the endoscopic findings bearing a close relationship to the duration of the condition 12 . The anatomopathological study of a surgical specimen will also allow the identification of Anisakis larvae. In the early stage of the parasitic infestation there is oedema and non-specific inflammatory infiltration; later stages invariably evidence an eosinophilic infiltrate that may involve only the mucosa, or also deeper layers of the intestinal wall (Figs. 4 and 5). Peritoneal involvement may be seen after perforation of the intestinal wall by the parasite has occurred. SKIN TESTS AND IGE DETERMINATIONS Skin prick tests The skin prick tests are usually performed with com- 269
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Page 5 and 6: as coronary artery disease or in th

Guidelines in pathology induced by Anisakis Original Article

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