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Diseases of Aquatic Organisms

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DAO 152:27-36 (2022)  -  DOI:

Prevalence and genotype of Toxoplasma gondii in stranded Hawaiian cetaceans

Nelmarie Landrau-Giovannetti1, Thomas B. Waltzek1, Natalia López-Orozco2,3, Chunlei Su3, David Rotstein4, Gregg Levine5, Thaís C. S. Rodrigues1, Ilse Silva-Krott6, Conner Humann6, Kristi West6,7,*

1Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA
2Facultad de Ciencias de la Salud, Universidad Tecnológica de Pereira, Risaralda 660003, Colombia
3Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA
4Marine Mammal Pathology Services, Olney, MD 20832, USA
5Dolphin Quest, Honolulu, HI 96816, USA
6Hawai‘i Institute of Marine Biology, University of Hawai‘i at Mānoa, Kāne‘ohe, HI 96744, USA
7Human Nutrition Food and Animal Sciences, College of Tropical Agriculture and Human Resources, Honolulu, HI 96822, USA
*Corresponding author:

ABSTRACT: Toxoplasma gondii is a significant threat to endangered Hawaiian wildlife including birds and marine mammals. To estimate the prevalence of T. gondii in stranded cetaceans from 1997 to 2021 in Hawai‘i, we tested tissues from 37 stranded spinner dolphins Stenella longirostris and 51 stranded individuals that represented 18 other cetacean species. DNA from cetacean tissue extracts were screened using a nested polymerase chain reaction (PCR) assay targeting the Toxoplasmatinae internal transcribed spacer 1 of the nuclear ribosomal DNA. A positive result was obtained in 9 tissues examined for each of 2 spinner dolphins out of 525 tissue samples analyzed by PCR. The PCR-positive spinner dolphins had disseminated acute toxoplasmosis with necrosis, inflammation, and intralesional protozoal cysts and tachyzoites in multiple organs. Discrete positive immunostaining for T. gondii was observed in all tissues tested including the adrenal gland, brain, liver, and lung. Both positive spinner dolphins were negative for cetacean morbillivirus. The T. gondii genotyping was performed by restriction fragment length polymorphism (PCR-RFLP) based on 10 genetic markers. The PCR-RFLP analysis revealed the T. gondii belonged to PCR-RFLP-ToxoDB genotype #24, previously detected in wild pig Sus scrofa in O‘ahu, bobcats Lynx rufus from Mississippi, USA, and chickens Gallus gallus from Costa Rica and Brazil. These cases represent the first report of this genotype in aquatic mammals and the second and third reports of fatal disseminated T. gondii infection in stranded spinner dolphins from Hawai‘i. Nearshore species, like spinner dolphins, may be at increased risk of mortality from this parasite in marine coastal waterways via sewage systems, storm water drainage, and freshwater runoff.

KEY WORDS: Disseminated toxoplasmosis · Spinner dolphin · Stenella · Wildlife · Hawai‘i · Genotype · PCR-RFLP

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Cite this article as: Landrau-Giovannetti N, Waltzek TB, López-Orozco N, Su C and others (2022) Prevalence and genotype of Toxoplasma gondii in stranded Hawaiian cetaceans. Dis Aquat Org 152:27-36.

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