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Source: http://www.montereyherald.com/local/ci_10814087
OUTBREAK STRIKES DOWN SEA LIONS
Scientists study rise of often-fatal kidney disease
By LIZZIE BUCHEN
Herald Staff Writer
Article Last Updated: 10/25/2008 01:30:06 AM PDT
The boisterous barking of Monterey's sea lions is a little quieter this year. A large number of the animals have fallen sick or died from a kidney-ravaging disease called leptospirosis, and the Marine Mammal Center in Sausalito is launching a new study to find out why.
Leptospirosis affects California sea lions each year, but every four to five years the number of cases surges. The last outbreak was in 2004, when 45 percent of all sea lions brought to the MMC were diagnosed with leptospirosis ? compared to only 4.5 percent in 2003. MMC veterinarians say 2008 is proving to be another outbreak year.
The new research seeks to understand why the outbreaks occur. Scientists will take blood samples, tag and release wild juvenile sea lions over a range from Monterey Bay to San Francisco Bay.
"We've been watching this disease play out for decades," MMC executive director Dr. Jeffrey Boehm said, but he said many important questions still need answers.
Although scientists have conducted a number of studies on leptospirosis, Boehm said, they have focused on stranded animals ? animals brought into rehabilitation centers such as the MMC that are sick or injured. This bias makes it difficult to understand how the disease affects the population as a whole.
"What hasn't happened is a proactive attempt to get out into the local waters and assess the wild population," he said. By catching and releasing wild sea lions, researchers can study animals that appear healthy but may have been exposed to leptospirosis and have recovered or don't show any symptoms.
"Our team is skilled at rescuing animals along beaches and in the open water, so they can also safely maneuver healthy animals into a net and take blood samples before releasing them," Boehm said.
Boehm hopes the new data will help scientists understand the stages of the disease and how animals become infected.
Leptospirosis wreaks havoc on the sea lions' kidneys, which remove waste products from the blood and control the amount of water in the body. While most animals at the MMC are sick or weakened, Boehm said, leptospirosis-stricken sea lions are wretched in comparison. In severe cases, the pain causes sea lions to lie flat on their sides, their rear flippers tucked against their abdomens.
"The harbor seals and elephant seals may arrive undernourished, but they seem happy and they gain weight. But even people touring the center with no animal background can tell that these sea lions are ill. They're really down and out."
When people see sick sea lions on the beach, the scene is even more tragic.
"Their bodies are so dehydrated," said Boehm. "They seek water anywhere they can find it. They lie there digging their noses into the wet sand just to try to get any water out of it."
The MMC treats sick sea lions with fluid therapy and antibiotics, but Boehm said a significant fraction of the infections are fatal.
Scientists documented the first case of leptospirosis in California sea lions in 1970, and have observed outbreak cycles since 1984.
Boehm noted that "this is one disease, one species we're looking at with this study. But at our core, we're a rehab center and we're trying to get animals healthy and return them to the wild. As we do that, we're learning more and more about the oceans and how these animals and ocean health are faring. We're finding some very interesting things."
Many other animals, including livestock, dogs and humans, can become infected through contact with contaminated urine, water or soil. If left untreated, patients can develop kidney damage, meningitis, liver failure and respiratory distress.
The MMC warns beachgoers and their dogs not to approach marine mammals. Call the center's 24-hour response line at 415-289-SEAL about animals in distress.
OUTBREAK STRIKES DOWN SEA LIONS
Scientists study rise of often-fatal kidney disease
By LIZZIE BUCHEN
Herald Staff Writer
Article Last Updated: 10/25/2008 01:30:06 AM PDT
The boisterous barking of Monterey's sea lions is a little quieter this year. A large number of the animals have fallen sick or died from a kidney-ravaging disease called leptospirosis, and the Marine Mammal Center in Sausalito is launching a new study to find out why.
Leptospirosis affects California sea lions each year, but every four to five years the number of cases surges. The last outbreak was in 2004, when 45 percent of all sea lions brought to the MMC were diagnosed with leptospirosis ? compared to only 4.5 percent in 2003. MMC veterinarians say 2008 is proving to be another outbreak year.
The new research seeks to understand why the outbreaks occur. Scientists will take blood samples, tag and release wild juvenile sea lions over a range from Monterey Bay to San Francisco Bay.
"We've been watching this disease play out for decades," MMC executive director Dr. Jeffrey Boehm said, but he said many important questions still need answers.
Although scientists have conducted a number of studies on leptospirosis, Boehm said, they have focused on stranded animals ? animals brought into rehabilitation centers such as the MMC that are sick or injured. This bias makes it difficult to understand how the disease affects the population as a whole.
"What hasn't happened is a proactive attempt to get out into the local waters and assess the wild population," he said. By catching and releasing wild sea lions, researchers can study animals that appear healthy but may have been exposed to leptospirosis and have recovered or don't show any symptoms.
"Our team is skilled at rescuing animals along beaches and in the open water, so they can also safely maneuver healthy animals into a net and take blood samples before releasing them," Boehm said.
Boehm hopes the new data will help scientists understand the stages of the disease and how animals become infected.
Leptospirosis wreaks havoc on the sea lions' kidneys, which remove waste products from the blood and control the amount of water in the body. While most animals at the MMC are sick or weakened, Boehm said, leptospirosis-stricken sea lions are wretched in comparison. In severe cases, the pain causes sea lions to lie flat on their sides, their rear flippers tucked against their abdomens.
"The harbor seals and elephant seals may arrive undernourished, but they seem happy and they gain weight. But even people touring the center with no animal background can tell that these sea lions are ill. They're really down and out."
When people see sick sea lions on the beach, the scene is even more tragic.
"Their bodies are so dehydrated," said Boehm. "They seek water anywhere they can find it. They lie there digging their noses into the wet sand just to try to get any water out of it."
The MMC treats sick sea lions with fluid therapy and antibiotics, but Boehm said a significant fraction of the infections are fatal.
Scientists documented the first case of leptospirosis in California sea lions in 1970, and have observed outbreak cycles since 1984.
Boehm noted that "this is one disease, one species we're looking at with this study. But at our core, we're a rehab center and we're trying to get animals healthy and return them to the wild. As we do that, we're learning more and more about the oceans and how these animals and ocean health are faring. We're finding some very interesting things."
Many other animals, including livestock, dogs and humans, can become infected through contact with contaminated urine, water or soil. If left untreated, patients can develop kidney damage, meningitis, liver failure and respiratory distress.
The MMC warns beachgoers and their dogs not to approach marine mammals. Call the center's 24-hour response line at 415-289-SEAL about animals in distress.