Epidemiology of hookworm (Uncinaria spp.) infection in New Zealand (Hooker’s) sea lion (Phocarctos hookeri) pups on Enderby Island, Auckland Islands (New Zealand) during the breeding seasons from 1999/2000 to 2004/2005

Abstract

This is the first investigation of the epidemiology of hookworm (Uncinaria spp.) infection in New Zealand sea lions (NZSLs; Phocarctos hookeri) on Enderby Island, Auckland Islands. The examination of faeces for hookworm eggs in various age categories of sea lions revealed that only pups up to at least 3 months of age harboured adult hookworms in their intestines. Gross necropsy of more than 400 pups from 1999/2000 to 2004/2005 showed that the prevalence of hookworm infection varied significantly between years and was higher from mid-January to the end of February when the majority of pups were between 3 and 9 weeks old. The average burden of adult parasites per pup was not influenced by the host's sex and body condition or by year. This study also provided evidence for transmission occurring by the transmammary route in NZSLs.

Neonatal Mortality in New Zealand Sea Lions (Phocarctos Hookeri ) at Sandy Bay, Enderby Island, Auckland Islands From 1998 to 2005

“…Klebsiella pneumoniae was the most significant pathogen isolated from a wide range of tissues and lesions in both 2001-02 and 2002-03, and it was also isolated from dead pups in the years subsequent to the epidemics. However, attempts to isolate this pathogen from archived samples collected prior to the 2001-02 epidemic failed (Castinel et al, 2007b). Several different Salmonella enteriditis subspecies (serotypes Cerro, Derby, and Newport) were also identified from pup feces collected at necropsy over the whole period of study.…”

“…The lower proportion of pups diagnosed with hookworms in 2001-02 (9.2%) and 2002-03 (9.8%) is more likely to be due to pups dying from acute bacterial infection and septicemia (38.3% and 33.3%, respectively) before 3 wk of age rather than a lower intensity of parasites during the epidemic years. The epidemiology of hookworm infection in New Zealand sea lion pups was investigated at Sandy Bay Beach rookery and is reported as a separate study (Castinel et al, 2007a).…”

“…data), had no blubber layer, and had hepatic atrophy. Hookworm enteritis was characterized by copious bloody content in the intestine, serosal ecchymoses, high worm burdens (mean individual burden: 824 hookworms; Castinel et al, 2007a), and anemic carcasses. Bacterial infection included any or all of the following: septicemia, suppurative pleuritis, peritonitis or meningitis, abscesses, suppurative or necrotizing pneumonia, and suppurative arthritis.…”

The diversity and impact of hookworm infections in wildlife

“…can cause up to 70% mortality in some colonies of California sea lions (Spraker et al., 2007). In other species, such as New Zealand sea lions, northern fur seal, Australian sea lions and South American fur seals, hookworms cause between 15 and 50% of total pup mortality (Castinel et al., 2007a, Lyons et al., 2011a, Seguel et al., 2013, Marcus et al., 2014a). In other mammalian groups, reports of hookworms causing mortality are sporadic, as in the case of Uncinaria sp nematodes causing the death of a brown bear pup in Turkey (Kilinc et al., 2015), and the role of Grammocephalus hybridatus in the death of several young Asian elephants transported to a zoo (Romboli et al., 1975).…”

Increasing pup production of New Zealand sea lions at Campbell Island/Motu Ihupuku: can it continue?

“…Lesions like these were not observed in any pups at Paradise Point or anywhere at the Auckland Islands and have never previously been reported for any other sea lion species. Flipper lesions may allow infection (such as hookworm) to enter the body (Castinel, Duignan, Lyons et al 2007;) and, in some cases, were so severe that they are likely to have restricted movement, thus increasing the pups' likelihood of death or injury by trauma.…”