TOXOPLASMOSIS, SEA MAMMALS OPF WORLDWIDE

Toxoplasma gondii_ is a protozoan parasite, which causes toxoplasmosis, considered to be the 3rd leading cause of death attributed to foodborne illness in the United States.While the Centers for Disease Control and Prevention estimates that over 20 per cent of the US population carries the parasite, the only known reservoir of the infectious form of the parasite (the oocyst) are cats. Over the past decade, toxoplasma infection has appeared in a variety of sea mammals including beluga whales, dolphins, sea lions, and seals. It has also become a major cause of death in sea otters living off the coast of California.It is estimated that about 17 per cent of sea otter deaths can be attributed to toxoplasma.While many believe fresh water runoff contaminated with cat feces is to blame, there is no definitive science on the source of infection. The question that drives our research is: how are marine mammals from the Arctic Circle to Australia infected by a parasite that is spread primarily through the consumption of infectious cat feces and infected meat?Based on the global prevalence of _T. gondii_ infections, we hypothesize that migratory filter feeders, specifically northern anchovies, are serving to spread _T. gondii_ throughout the ocean, says Gloeta Massie, a graduate student who conducted the research with associate professor Michael Black. There is no previously published research on the ability of anchovies to filter oocysts, that was the 1st step towards proving their hypothesis. Massie and Black exposed northern anchovies to the parasite, and then, using molecular techniques, tested for the presence of the parasite within the fish.They detected _T. gondii_ DNA in 66 per cent of the exposed fish. Now that they have shown that anchovies can filter oocysts from the water, the next step is to determine the infectivity of exposed anchovies to mammals.Do our research findings mean that you should stop eating anchovy pizza? No. _T. gondii_ oocysts are destroyed by high heat. Unfortunately, marine mammals do not have the option of cooking their food before they eat it. As anchovies are considered prey for practically every major predatory marine fish, mammal, and bird, if the exposed anchovies harbor infectious oocysts, this could present a possible transmission path of _T. gondii_ in the marine environment, says Massie.