# Gastric lesions associated with the infection of Anisakidae nematodes in a dwarf sperm whale Kogia sima (Owen, 1866) stranded in the north coast of Brazil

## TL;DR

This study reports gastric lesions in a dwarf sperm whale caused by Anisakidae nematodes and confirms the presence of these parasites in a new geographic location in Brazil.

## Contribution

The study documents the first occurrence of Kogia sima in northern Brazil and identifies multiple anisakid species causing gastric lesions in this whale.

## Key findings

- Gastric lesions including ulcers and erosions were observed in the whale's stomach associated with anisakid infection.
- Molecular analysis confirmed the presence of Skrjabinisakis paggiae with high DNA sequence identity.
- The dwarf sperm whale was found in the estuary region of the Pará river, a new geographic record for this species in Brazil.

## Abstract

The present study aimed to describe gastric lesions associated with parasitism by different nematodes of the family Anisakidae in a stranded specimen of dwarf sperm whale (Kogia sima) on the northeast coast of the State of Pará, northern Brazil. Specimens of helminths and samples of stomach tissue were collected from a dwarf sperm whale, stranded on Humaitá beach, State of Pará, Brazil. Stomach showed areas of erosion and ulcers, with the mucosa covered by fibrinonecrotic material containing bacteria and inflammatory infiltrate predominantly comprising polymorphonuclear cells. Granulomas were also found in the submucosa, characterized by central areas of necrosis and hemorrhage, and cross sections of nematodes were observed. Fourth-stage larvae of the genus Pseudoterranova, two morphotypes of fourth-stage larvae of the genus Anisakis and adult specimens of Skrjabinisakis paggiae were morphologically identified. Molecular and phylogenetic analyzes confirmed the identity of the partial sequences of the cox2 mtDNA gene for adult specimens of S. paggiae. This study contributes to our understanding of the distribution of different of anisakids in K. sima and about the gastric lesions associated with these nematodes, in addition to expanding the knowledge about the occurrence of this aquatic mammal recorded for the first time in the northern region of Brazil.

Image 1

•Kogia sima was parasitized by three larvae species and one adult of anisakids infecting the gastric mucosa.•Gastric ulcerative and erosions lesions associated with anisakids infection were observed.•Cox-2 mtDNA sequences from specimens analyzed revealed 99.67% identity with partial Cox-2 mtDNA sequences from A. paggiae.•Kogiasima was found in a peculiar geographic location, the estuary region of the Pará river.

Kogia sima was parasitized by three larvae species and one adult of anisakids infecting the gastric mucosa.

Gastric ulcerative and erosions lesions associated with anisakids infection were observed.

Cox-2 mtDNA sequences from specimens analyzed revealed 99.67% identity with partial Cox-2 mtDNA sequences from A. paggiae.

Kogiasima was found in a peculiar geographic location, the estuary region of the Pará river.