|Notas e Informações|| |
Notes and Information
Human case of gastric infection by a fourth larval stage of Pseudoterranova decipiens (Nematoda, Anisakidae)*
Relato de parasitismo por nematódeo Anisakidae em homem
Rubén Mercado, Patricio Torres and Jorge Maira
Departamento de Parasitología de la Universidad de Chile. Santiago, Chile (R.M.); Instituto de Parasitología de la Universidad Austral de Chile. Valdivia, Chile (P.T.); Clínica Integramédica. Sección Gastroenterología. Santiago, Chile (J.M.)
|Only three cases of human infection by anisakid nematodes have been reported in Chile since 1976. In the present case, an anisakid worm, identified as a fourth-stage Pseudoterranova decipiens larva, was removed with a gastroendoscopic biopsy clipper from the stomach of a 45 year-old man from southern Chile. The patient, who presented acute epigastric pain and a continuous sensation of having an empty stomach, reported having eaten smoked fish. The worm was fixed in 70% ethanol and cleaned in lactophenol for morphological study. The morphometric characteristics of the worm are described and drawn. Anisakid larvae in fish flesh can be killed by freezing or cooking.|
|Nematode infections. Anisakiasis.|
|Um anisakidio, identificado como larva do quarto estágio de Pseudoterranova decipiens, foi isolado por gastroendoscopia do estômago de uma pessoa de 45 anos de idade, residente no Sul do Chile. Relata-se que o paciente apresentou dor epigástrica aguda e sensação de estômago vazio, tendo ingerido peixe defumado. O nematode foi fixado em etanol 70% e diafanizado com lactofenol para estudo morfológico.|
|Infecções por nematóides. Anisaquiase.|
|Un gusano anisákido identificado como larva del cuarto estadio de Pseudoterranova decipiens fue aislado mediante gastroendoscopio en el estómago de una persona de 45 años, residente en el sur de Chile. Se relató que el paciente presentó dolor epigástrico agudo y sensación de estómago vacío, siendo consumidor de pescado ahumado. El gusano fue fijado en etanol de 70% y diafanizado en lactofenol para su estudio morfológico.|
|Infecciones por nematodos. Anisakiasis.|
In Chile, four food-borne helminthic zoonoses are associated with the consumption of raw, smoked or undercooked fish. Two of those infections are caused by the nematodes Anisakis simplex and Pseudoterranova decipiens, and the other two are produced by the cestodes Diphyllobothrium latum and Diphyllobothrium pacificum. Except for D. latum which infects salmonids and authocthonous fish introduced into sweetwater16, other parasites are transmitted to man by his eating sea fish9, 15, 17.
Human infections produced by larval stages of P. decipiens are commonly named anisakiasis in the broad sense5, codworm anisakiasis12 or Pseudoterranovosis according to standardized nomenclature of animal parasitic diseases6. Although third or fourth stage larvae of anisakid worms can produce human infections, the latter are only rarely found4, 5.
To the present day in Chile, only three cases of human infection produced by anisakid worms have been reported1, 14, 20. It is described a new case of human infection, produced by a fourth larval stage or P. decipiens in a patient who resided in the south of Chile.
A 45 year-old man, living in Coihaique City (45o33'S Lat., 72o 06'W Long) travelled periodically to Santiago on business. In June 1995, he presented acute epigastric pain and a sensation of an empty stomach which continued for three days. No other symptoms were registered. He was given a gastric endoscopy without any other laboratory exams and had no morbid antecedents. The patient reported having eaten smoked fish. Endoscopic study showed a nematode fixed to the slightly, hyperaemic gastric mucous in the posterior region,whence it was removed directly with a gastroendoscopic biopsy clipper.
The nematode was fixed in ethanol 70% and was later cleaned in lactophenol for morphometric studies (Figure). Measurements are in mm: the body of the larva was 32.2 in length; greatest diameter near midbody was 0.72. The mouth had three lips: a dorsal one showed two double papillae and each subventral lip presented a single double papilla. Interlabia and boring tooth were absent. Excretory pore opened between two subventral lips. Nerve ring was 0.41 from anterior end. Esophagus or preventricule measured 2.2 in length and 0.27 at maximum width. Ventricule and intestinal cecum were 1.1 in length. The tail was 0.2 in length with a knoblike process.
Figure - Larva of Pseudoterranova decipiens: m = mouth, p = preventriculus, c = intestinal cecum, i = intestine, v = ventriculus, a = anus.
The morphometric characteristics of the recovered larva corresponded to a fourth stage of P. decipiens4 and it is the first report of this larval stage in a human case in Chile.
Nagano10 reportedthat human cases of infection produced by P. decipiens in Japan involved the stomach of the patients. Our observation is in agreement with that finding.
About 18 species of marine fish (Table) have been reported as hosts of the third larval stage of codworm in Chile2, 3, 11, 15. Adults of P. decipiens have been identified from seals Otaria byronia and Arctocephalus philippi in Chile15. Also, adults of Pseudoterranova sp. have been isolated in the dolphin Cephalorhynchus eutropia and in the porpoise Phocoena spinipinnis18. Genetic studies of P. decipiens recovered from sea mammals captured in the north Atlantic and Norwegian and Barents seas showed that P. decipiens is a complex of at least three sibling species13.
Sapunar et al.14 described the first case of anisakiasis in Chile in a women of 35 years old from Santiago. In this case one larva of Anisakis sp. was expectorated by the patient and an other was eliminated with the faeces after treatment with mebendazole. Apt et al.1 described a second case in a female of Japanese ancestry. A worm was removed with the biopsy forceps from the stomach of the patient. It was identified as a Pseudoterranova sp. larva. Verhamme and Rauher20 described a case of intestinal anisakiasis in a Belgian tourist who probably acquired the infection in Chile. Worms were not recovered from this patient.
Anisakid larvae present in fish flesh would be killed by freezing at _20 oC for 60 hrs9. According to Margolis7 cooking 3 cm-thick fish fillets of at 70 oC or 60 oC for 7 or 10 minutes, respectively, should kill any codworm larvae present.
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19. TORRES, et al. Registro de nuevos casos de difilobotriasis humana en Chile (1981-1992), incluido un caso de infección múltiple por Diphyllobothrium latum. Bol. Chileno Parasitol., 48: 39-43, 1993.
20. VERHAMME, M.A.M. & RAMBOER, C.H.R. Anisakiasis caused by herring in vinegar: a little know medical problem. Gut, 29: 843-7, 1988.
* Presented in the XII Congreso Latinoamericano de Parasitología (October, 1995), Santiago, Chile. Supported by Dirección de Investigación y Desarrollo: Universidad Austral de Chile. Proyecto S-94-24.
Correspondence to: Patricio Torres - Instituto de Parasitología de la Facultad de Medicina de la Universidad Austral de Chile, Isla Teja. Avenida Inés de Haverbeck nº 12. Valdivia, Chile. Fax: 063-214475.
Received on 12.11.1996. Approved on 25.11.1996.