Seroepidemiology of Toxoplasma gondii and Neospora caninum in Seals around Hokkaido, Japan

Abstract

ABSTRACT. Serological analysis was performed to detect Toxoplasma gondii and Neospora caninum infection in seals in Hokkaido. Serum samples were collected from 322 Kuril harbor seals (Phoca vitulina stejnegeri) at Nosappu, Akkeshi and Erimo, from 46 spotted seals (P. largha) at Nosappu, Erimo, Yagishiri Island, Hamamasu and Syakotan, and from 4 ribbon seals (P. fasciata) and a bearded seal (Erignathus barbatus) Toxoplasma gondii and Neospora caninum, which are apicomplexan protozoa with worldwide distribution, cause neuromuscular disease and abortion through transplacental transmission in warm-blooded hosts [6,37]. T. gondii and N. caninum infections have been reported mainly in terrestrial mammals and birds, although recently they have been found in wild marine mammals, including several species of seals [8]. T. gondii infection is known to be a major cause of encephalitis in sea otters (Enhydra lutris) [4,8]. The ingestion of oocysts in contaminated food or water and the ingestion of infected tissues of intermediate hosts are the two main sources of postnatal T. gondii and N. caninum infection. Felids and dogs are the only known host that can excrete environmentally resistant oocysts of T. gondii and N. caninnum, respectively [6,37]. Miller et al. [20] presented evidence that land-based surface runoff was a significant risk for T. gondii infection in sea otters. It is possible that oocysts of these protozoa wash into the sea in runoff contaminated by excrement of cats and dogs. In Hokkaido, influx of runoff contaminated with substances such as pesticides and organic matters into environmental water has been known, and it is particularly serious in the snowmelt season [29,30]. Cryptosporidium parvum oocysts that are genetically similar to C. parvum infected in cattle have been detected from river in Hokkaido [38]. If the coastal Hokkaido has been contaminated by terrestrial protozoa, marine mammals may have been infected.Around Hokkaido, there are 5 species of seals: The Kuril harbor seal (Phoca vitulina stejnegeri), the spotted seal (P. largha), the ringed seal (P. hispida), the ribbon seal (P. fasciata) and the bearded seal (Erignathus barbatus) [16]. Kuril harbor seals are distributed along the northwestern Pacific coast [17]. These seals haul out year round on rocky reefs near land and have a strong fidelity to their particular hauling-out site [28]. The four other species migrate in winter and spring, drifting south to Hokkaido with the packed ice [16]. The four species are distributed in the Sea of Japan and the Sea of Okhotsk mainly, although some spotted seals can be found along the Pacific coast all the year round [15,23,24]. Miller et al. [21] reported antibodies against N. caninum from an encephalitic Pacific harbor seal (P. v. richardsi) that had demonstrable T. gondii and Sarcocystis neurona in encephalitic lesions. For proper management and conservation of seals, information on the prevalence of the protozoa, which can be the death of seals, is indispensable. The infection of pathogenic protoz...

Seroprevalence of Toxoplasma gondii in North-eastern Atlantic harbor seal (Phoca vitulina vitulina) and grey seal (Halichoerus grypus)

“…Seroprevalence studies of T. gondii antibodies in pinnipeds have been reported in several species but in a few restricted geographical areas: North America, Hawaii islands, and Japan (Lambourn et al, 2001;Dubey et al, 2003Dubey et al, , 2004Measures et al, 2004;Aguirre et al, 2007;Fujii et al, 2007). The prevalence of antibodies against T. gondii detected in the present study in Atlantic harbor seal (5.4%) is similar to the 9% seroprevalence previously reported by Measures et al (2004) in Atlantic harbor seal from the east coast of Canada and the 4% seroprevalence reported by Fujii et al (2006) in Kuri harbor seals from Japan, but lower than the 16.4% detected in Pacific harbor seals from Alaska (Dubey et al, 2003).…”

“…Infection via intermediate hosts is unlikely because seals do not prey on warm-blooded animals (Fujii et al, 2007). The role of vertical transmission is unknown although vertical transmission has been observed in cetaceans (Resendes et al, 2002), and probable T. gondii maternal antibody transfer was observed in one harbor and one grey seal pup at 10 and 14 days of age, respectively .…”

“…To the authors' knowledge this is the first serological survey of T. gondii in European grey and harbor seal populations. Contamination of marine environment and marine organisms by pathogenic protozoa should be monitored and appropriate run-off management measures might be implemented to avoid oocyst contamination of the sea environment as suggested by Fujii et al (2007).…”

“…Numerous serologic surveys to determine the seroprevalence of antibodies against T. gondii have been carried out in seals (Fam. Phocidae) and T. gondii antibodies have been found in several species such as Pacific harbor seal (Lambourn et al, 2001;Dubey et al, 2003), western Atlantic harbor seal (Phoca vitulina concolor) , kuril harbor seal (Phoca vitulina stejnegeri) (Fujii et al, 2007), ringed seal (Phoca hispida), bearded seal (Erignathus barbatus) and spotted seal (Phoca largha) (Dubey et al, 2003), grey seal (Halichoerus grypus) and hooded seal (Cystophora cristata) , and worldwide reports in these animals were recently reviewed (Dubey, 2009). Compared to these reports, antibodies against T. gondii were not found in harp seal (Phoca groenlandica), ringed seal (P. hispida) and hooded seal (C. cristata) in the Northeast Atlantic Ocean (Oksanen et al, 1998).…”

Discovery of Three Novel Coccidian Parasites Infecting California Sea Lions (Zalophus californianus), with Evidence of Sexual Replication and Interspecies Pathogenicity

“…infection has most commonly been reported in Pacific harbor seals (Lapointe et al, 1998; Colegrove et al, 2005). Serologic analysis using a recombinant antigen derived from the major surface antigen NcSAG1 detected antibodies consistent with infection by Neospora caninum in harbor seals and spotted seals ( Phoca largha ) in Japan (Fujii et al, 2007). Exposure to N. caninum has been postulated in walrus ( Odobenus rosmarus ), sea otters (Enhydra lutris nereis ), harbor seals, sea lions, ringed seals ( Phoca hispida ), bearded seals ( Erignathus barbatus ), and bottlenose dolphin ( Tursiops truncatus ) based on serology using an N. caninum agglutination test (Dubey et al, 2003).…”