Treatment of northern fur seal (Callorhinus ursinus) pups with ivermectin reduces hookworm-induced mortality

  • Published source details DeLong R.L., Orr A.J., Jenkinson R.S. & Lyons E.T. (2009) Treatment of northern fur seal (Callorhinus ursinus) pups with ivermectin reduces hookworm-induced mortality. Marine Mammal Science, 25, 944-948.


This study is summarised as evidence for the following.

Action Category

Use drugs to treat parasites

Action Link
Marine and Freshwater Mammal Conservation
  1. Use drugs to treat parasites

    A controlled, before-and-after study in 2006 on an island in the North Pacific Ocean, off the coast of California, USA (DeLong et al. 2009) found that northern fur seal Callorhinus ursinus pups treated with an anti-parasitic drug (ivermectin) had reduced hookworm Uncinaria lucasi infections, lower mortality rates and greater growth rates than untreated pups. The number of treated pups with hookworm infections decreased from 24% (36 of 151 pups) to 6% (2 of 34 pups) 19–34 days after treatment with ivermectin. In comparison, the number of infected untreated pups increased from 24% (36 of 149 pups) to 67% (20 of 30 pups). Mortality rates were lower for pups treated with ivermectin (10 of 149 pups died, 7%) than untreated pups (50 of 151 pups died, 33%), and growth rates were greater (treated: 0.06 kg/day; untreated: 0.04 kg/day). In July 2006, seal pups were captured, tagged and alternately assigned to a treatment group (injected with ivermectin; 151 pups) or untreated control group (injected with saline solution; 149 pups). Hookworm eggs were counted in faecal samples in July (all of 300 pups) and August 2006 (34 treated pups, 30 untreated pups). Pups were weighed in July (all of 300 pups) and September 2006 (number not reported). Mortality surveys were carried out every 3–20 days in July–December 2006.

    (Summarised by: Anna Berthinussen)

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