The recent deaths of three critically endangered Hawaiian monk seals on Oahu due to toxoplasmosis could have been preventable, according to a joint statement from the heads of the Hawaii Departments of Health (DOH) and Land and Natural Resources (DLNR).
Cats are the only known reproductive host of the toxoplasmosis parasite. It reproduces in the feline digestive system. A single cat can excrete 145 billion eggs per year in its feces. Once released into the environment, these eggs can infect other animals, including humans, both on land and in the ocean. Toxoplasmosis parasites create cysts in muscle and organ tissues and can cause inflammation of the heart, liver, and brain.
Health Director Dr. Bruce Anderson said in a press release that the parasite that NOAA veterinarians found caused the deaths of the seals is impacts more than just marine mammals and wildlife, but toxoplasmosis is a risk to humans.
“It is known to cause serious problems for pregnant women and their unborn children,” Anderson said. “During pregnancy, infection by the toxoplasmosis parasite can damage the unborn child, causing miscarriages, stillbirth, or substantial birth defects including enlargement or smallness of the head.
For healthy individuals, symptoms and signs of toxoplasmosis infection are most often benign because a healthy person’s immune system usually keeps the parasite from causing illness. Very few people will have symptoms similar to the flu and most people probably do not know they have been infected. The Centers for Disease Control and Prevention estimates that approximately 10 percent of the population in the U.S. six years of age and older have developed antibodies to the parasite from a past infection. However, for those with compromised immune systems, those undergoing chemotherapy or with AIDS, and for pregnant women the disease can be very serious.
In Hawaii, the National Oceanographic and Atmospheric Administration has recorded at least 11 Hawaiian monk seal deaths that are attributable to toxoplasmosis infection since the first confirmed deaths in 2001. Spinner dolphins are the only other marine species that have been documented as dying from toxoplasmosis in Hawaii.