Saving the Sea Otters from T. Gondii

Size: px

Start display at page:

Download "Saving the Sea Otters from T. Gondii"

Anne Higgins
6 years ago
Views:

1 1 Kira Segenchuk STW Section A 19 September 2016 Saving the Sea Otters from T. Gondii Purpose The purpose of this project is to stop decline in the southern sea otter population of California by minimizing exposure to Toxoplasma gondii, a parasite that has recently been affecting the sea otters of California. This can be achieved by vaccinating cats along the otter s coastal range against T. gondii. While there have been other conservation efforts for sea otters, none have yet addressed the T. gondii problem. The main plan of this organization is to improve upon the current T. gondii vaccine for cats by finding a new strain or improving on the methods associated with the current vaccine to make it an easier to access and use the vaccine. This will be done in conjunction with measures to educate the public and make them more aware of the effects of T. gondii on both marine life and humans. Although this project will focus mainly on vaccinating cats in certain parts of California, this project could be expanded to cover the entire country, thereby benefiting the larger human population. Roughly $1.5 million will be needed in order to cover the costs of investigating and producing the vaccine including the expense of cats and mice used in testing the vaccine (International Development Research Centre, 2016). This may seem like a large sum of money, but it is nothing compared to the $7.7 billion per annum in medical costs and productivity losses caused by T. gondii infections in the USA (Buzby & Roberts, 1997).

2 2 Background Sea otters (Enhydra lutris) are an endangered species of otter which are found along the coasts of the Pacific Ocean in North America and Russia. Sea otters are a keystone species that play an important and essential part in their ecosystem by eating the sea urchins that feed on kelp, which works to maintain the coastal kelp forests. Kelp forests sequester carbon, and hence offset greenhouse gas effects (Leighton, 1966). While much of the northern sea otter population has been recovering since near extinction from being hunted for fur in the 1800s, the southern population (Enhydra lutris nereis) has not had similar success. An analysis of southern sea otter carcasses recovered from 1998 through 2001 found that 63.8% of the otters died due to disease, parasitic disease alone accounted for 38.1% of deaths, and 28% of the deaths were from protozoal meningoencephalitis (Kreuder et al., 2003). Toxoplasma gondii is a protozoan that can cause protozoal meningoencephalitis in sea otters, and is found in 36% of dead sea otters (Miller et al., 2002). Surprisingly, T. gondii does not naturally occur in the ocean. The only host animal that T. gondii can reproduce in is cats. This means that T. gondii oocysts released in the feces of cats must be making their way to the ocean and thus infecting the sea otters. It has been found that sea otters in areas of maximal freshwater outflow are nearly 3 times more likely to be infected with T. gondii than sea otters from other sites (Miller et al., 2002). This indicates that it is freshwater runoff that brings the most T. gondii to the ocean. Marine animals are not the only animals affected by T. gondii. T. gondii also affects humans and the animals they farm. Although it might be relatively common knowledge that T.

3 3 gondii is dangerous for pregnant women to contract, few may know that T. gondii accounts for 20.7% of deaths from food borne illness. This places T. gondii as third on the list of top foodborne pathogens causing human death in the USA (Mead et al., 1999). T. gondii can be spread to humans through the food they eat, oocysts shed from cats, or congenitally (Center for Disease Control and Prevention, 2015). By vaccinating cats to stop them from shedding the oocysts, human lives, as well as the lives of endangered sea otters, can be saved. Plan There are multiple ways to address the problem of T. gondii infecting sea otters, including (1) filtering out the T. gondii from the freshwater outflow, (2) vaccinating otters or the animals (e.g., cats) that carry and pass along T. gondii parasite, and (3) finding a way to build up sea otter immunity. The most effective solution would be one that stops T. gondii at its source: vaccinating cats. With this approach, not only will sea otters benefit, but other animals and humans damaged by T. gondii will as well. The best way to prevent the spread of oocysts from cats is to vaccinate cats so that when exposed to T. gondii, they will not release oocysts in their feces. Currently the most effective way to do this is with a strain of T. gondii that never reaches the stage of making oocysts, this way, the cats become infected, but won t shed any oocysts, and when they come into contact with T. gondii again, they also won t shed them. Although no groups have used this method to help sea otters yet, there does exist such a vaccine that involves using the T-263 strain. There are many drawbacks to this vaccine though. For example, it has a very short shelf-life. It must be produced by infecting mice and then harvesting the cysts from their brains (Innes et al., 2009). With the money from this grant, the highly skilled team of veterinary immunologists plans to find another strain of T. gondii that works to the same effect,

4 4 but has a longer shelf-life, and is easier to make. This will require funds for studying different strains and will incur the costs of animals for testing. After the vaccine has been developed, money from profits can be used to compensate for the money put into the development of the vaccine. Even if the attempts to make a new vaccine fail, the current one, T-263, can be used in the areas that most affect sea otters in order to minimize the amount of T. gondii they are exposed to. Following the development of the vaccine, we will launch phase two of the project, which includes educating people to make sure that they know of the dangers of T. gondii both to themselves and the environment. There will also be work on advertising the product so that the public becomes aware of the vaccine. Our marketing and public relations department will make ad campaigns that include facts about how the parasite affects humans and sea otters alike. Also, with the newly made vaccine, volunteer groups can work to catch feral cats in the coastal areas most contaminated by T. gondii and vaccinate them. These areas include Morro Bay and Elkhorn Slough (Miller et al., 2002). The program can start here, and if successful, can be expanded to more areas. The success with the initial areas should demonstrate effectiveness and encourage more people to use the vaccine.

5 5 References Buzby, J.C., Roberts, T. (1997). Economic costs and trade impacts of microbial foodborne illness. World Health Stat. Q. 50, Center for Disease Control and Prevention. (2015, March 26). Epidemiology & Risk Factors. Retrieved September 21, 2016, from Innes, E. A., Bartley, P. M., Maley, S., Katzer, F., & Buxton, D. (2009). Veterinary vaccines against Toxoplasma gondii. Mem. Inst. Oswaldo Cruz Memórias Do Instituto Oswaldo Cruz, 104(2). doi: /s International Development Research Centre (2016). Global Call for Research Proposals: Innovations in Livestock Vaccines. Retrieved September 22, 2016, from livestock-vaccines Kreuder, C., Miller, M.A., Jessup, D., Lowenstine, L.J., Harris, M.D., Ames, J.A., Carpenter, T.E., Conrad, P.A., Mazet, J.K. (2003). Patterns of mortality in southern sea otters (Enhydra lutris nereis) from J. Wildl. Dis. 39, Leighton, D.L. (1966). Studies of food preferences in algivorous invertebrates in southern California kelp beds. Pacific Science 20, Mead, P.S., Slutsker, L., Dietz, V., McCaig, L.F., Bresee, J.S., Shapiro, C., Griffin, P.M., Tauxe, R.V. (1999). Food-related illness and death in the

6 6 United States. Emerg. Infect. Dis. 5, Miller, M., Gardner, I., Kreuder, C., Paradies, D., Worcester, K., Jessup, D., Dodd, E., Harris, M., Ames, J., Packharr, A., Conrad, P. (2002). Coastal freshwater runoff is a risk factor for Toxoplasma gondii infection of southern sea otters (Enhydra lutris nereis). International Journal or Parasitology, 32(8), doi: /s (02)

GRAY WHALE. Text source: The Marine Mammal Center

GRAY WHALE. Text source: The Marine Mammal Center GRAY WHALE Gray whales are found only in the Pacific Ocean, and they have one of the longest migrations of any mammal. During the summer, they live in the Arctic. In the fall, they travel to Baja California,