Use drugs to treat parasites

How is the evidence assessed?
  • Effectiveness
    50%
  • Certainty
    40%
  • Harms
    10%

Study locations

Key messages

  • Two studies evaluated the effects on marine mammals of using drugs to treat parasites. Both studies were in the North Pacific Ocean (USA).

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (2 STUDIES)

  • Survival (2 studies): One of two controlled studies (including one before-and-after study) in the North Pacific Ocean found that treating northern fur seal pups with an anti-parasitic drug (ivermectin) reduced mortality rates. The other study found that Hawaiian monk seal pups treated with an anti-parasitic drug (praziquantel) had similar survival rates to untreated pups.
  • Condition (2 studies): One of two controlled studies (including one before-and-after study) in the North Pacific Ocean found that northern fur seal pups treated with an anti-parasitic drug (ivermectin) had reduced hookworm infections and greater growth rates than untreated pups. The other study found that Hawaiian monk seal pups treated with an anti-parasitic drug (praziquantel) had similar parasite loads to untreated pups.

BEHAVIOUR (0 STUDIES)

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. 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.

    Study and other actions tested
  2. A controlled study in 2009–2010 on an island in the North Pacific Ocean, Hawaii, USA (Gobush et al. 2011) found that Hawaiian monk seal Monachus schauinslandi pups treated with an anti-parasitic drug (praziquantel) had similar parasite loads and survival rates to untreated pups. The number of faecal samples containing parasitic worms (cestodes Diphyllobothrium spp.) did not differ significantly between treated pups (44 of 46 samples, 96%) and untreated pups (43 of 44 samples, 98%). Survival rates also did not differ significantly between treated pups (20 of 23 pups survived, 87%) and untreated pups (19 of 20 pups survived, 95%). Forty-three tagged seal pups (<2 years old) were randomly assigned to a treatment group (injected with praziquantel; 23 pups) or an untreated control group (20 pups). Each of 43 pups was captured, weighed, measured, injected (treatment group only) and had faeces sampled up to four times, 8–16 weeks apart, between December 2009 and May 2010.

    Study and other actions tested
Please cite as:

Berthinussen, A., Smith, R.K. and Sutherland, W.J. (2021) Marine and Freshwater Mammal Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

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Marine and Freshwater Mammal Conservation

This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation
Marine and Freshwater Mammal Conservation

Marine and Freshwater Mammal Conservation - Published 2021

Marine and Freshwater Mammal Synopsis

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