Infectious Disease Updates

From Patricia Doyle, PhD

Date: 3 Aug 2003
From: ProMED-mail <>
Source: Portland Press Herald 2 Aug 2003 [edited]
Gulf of Maine whale deaths raising fears of toxic algae
More than 15 years after dead whales washed ashore at Cape Cod, history may be repeating itself.
Scientists investigating a cluster of whale carcasses in the Gulf of Maine say a near-invisible, toxic algae blamed for at least 14 whale deaths in 1987 may have struck again.
Blubber, skin, waste products and stomach fluid collected this week from 6 dead whales floating hundreds of miles off the Maine coast will help determine whether the culprit is an algal bloom, often called red tide because of its appearance when heavily concentrated.
Marine experts say the naturally occurring neurotoxin in the algae may have been passed to the whales by the small fish they eat. The toxin could have incapacitated the whales and kept them from breathing or feeding properly, said Donald Anderson, a principal investigator and senior biologist at Woods Hole (Massachusetts) Oceanographic Institution.
A team of researchers planned to revisit the carcasses on Monday to take water samples, knowing full well the difficult task they face searching for clues in a dynamic water system.
But, Anderson said, "If we can find the toxin in the whale tissue and find that there are still a lot of toxic cells in there, then we'll have the smoking gun, or at least the best we're going to get."
Authorities say at least 10 whales have been found dead in July near Georges Bank, an underwater plateau that extends from Cape Cod northeast to Nova Scotia and separates the Gulf of Maine from the Atlantic Ocean. It is about 200 miles southeast of Portland.
Casualties include one fin whale, one pilot whale, and between 6 and 12 humpback whales, according to the National Oceanic and Atmospheric Administration Fisheries in the Northeast. Dead whales are also cropping up in Canadian waters. Canadian news reports put the number at more than a dozen.
The whales had been dead for between a week and a month when they were found, said Teri Frady, spokeswoman for the federal agency, which is charged with large-whale protection.
If the test results, expected by next week, are inconclusive, experts may try to pull a more recently deceased animal to shore for more complete testing, Frady said.
Toxic algae has emerged as a probable cause as other suspected causes grow less likely. Anderson said veterinarians did not notice viral symptoms in the whales, and NOAA Fisheries said there were no obvious signs of trauma.
Large numbers of whale deaths are rare, and some scientists say an unusual set of events must have occurred, like the ones believed to have led to the 1987 whale deaths.
That year, mackerel had migrated south from the Gulf of St. Lawrence, where they likely ate toxic zooplankton, just as the whales were preparing to migrate to the Caribbean and needed to consume a lot of food to generate energy.
Because the sand lance typically eaten by the whales was in short supply that year, the animals switched to eating the toxic mackerel. [The sand lance is an elongated eel-like fish that swims in schools and embeds itself in the sand at ebb tide. - CopyEd.PG]
"The fish kept eating zooplankton without being killed and the poor whales didn't stop eating the fish until they were dead," said oceanographer David Townsend.
Townsend, director of the School of Marine Sciences at the University of Maine, said it is unlikely that the whales got sick near Georges Bank. He said fish likely consumed the algae in 2 areas in the Gulf of Maine that are prone to algal blooms -- the mouth of the Bay of Fundy and a patch located 50 miles south of Penobscot Bay.
"My guess is that the fish that had been eating the toxic zooplankton were followed to the point where the whales ate them and (then) moved onto Georges Bank," Townsend said.
Scientists say there is little chance that the toxic algae will find its way to the coast of Maine because of the currents -- good news for the shellfish industry. Algal blooms closer to the coast already force the state to regularly close shellfish beds on a temporary basis. In humans, toxins can cause dizziness, nausea, fever, paralysis, and even death.
John Hurst, who directs biotoxin monitoring in shellfish for the Maine Department of Marine Resources, said the state's monitoring system "will keep everyone from getting sick."
"If we find that shellfish are getting toxic, there'll be closings," he said. "The Maine patrol people will see to it that you won't harvest, and dealers don't want it anyway because they don't want to be sued by somebody."
Anderson agreed, praising Maine's shellfish monitoring system as "one of the best in the world."
[Byline: Josie Huang]
[The toxic algae found in marine water are usually a different species than those found in fresh water. Often times toxic algae blooms in marine water may go by the common name of red tide, although not all toxin marine algae cause a red coloring, and some fresh-water toxic algae may produce the red coloring. - Mod.TG]
Date: Thu 31 Jul 2003
From: Helena Spedding <>
Source: Reuters Report, Thu 31 Jul 2003 [edited]
Australia: Undiagnosed Cancer Killing Off Tasmanian Devils
A mysterious cancer is killing Australasia's Tasmanian devils -- whose spine-chilling screeches, dark colour, and reputed bad temper prompted early settlers to give them their chilling name. The world's largest carnivorous marsupial is the size of a stocky small dog but has jaws as strong as a crocodile that allow it to eat up to half its body weight in 30 minutes. An adult can weigh up to 12 kg.
Australia's southern island state of Tasmania is [now] the only place where the animals are found, but they are being affected by a virus-mediated disease that has cut some population groups by 85 percent. The population of _Sarcophilus harrisii_ peaked at around 175 000 in 1996 before the cancer appeared. Now wildlife officials fear the disease could kill 2/3 of the population by 2006. The affliction has spread widely in eastern and central Tasmania in 2 years. It causes huge tumours that block the animal's eyesight, hearing, or mouth, and they starve to death.
"We suspect it is spread by biting when the animals quarrel or mate," said Nick Mooney, a wildlife biologist with the nature conservation branch of the state's wildlife department. However, it is unlikely that the cancer will wipe out the Tasmanian devil, as such diseases often spare a few isolated animals, which then reproduce to revive the population. "We may find there is nothing more we can do than isolate parts of the population," Mooney said.
Helena Spedding
Deputy Editor
Animal Pharm
[The evidence for a viral etiology is unclear from this report, but the
description of the disease resembles that of a poxvirus-associated hyperplasia, such as myxomatosis in rabbits. Further information on the nature of the disease and its relationship to myxomatosis, if any, would be welcomed.
Tasmanian devils are restricted to Tasmania, and it is believed they became extinct on mainland Australia some 600 years ago -- before European settlement of the continent. The dingo, which was brought into Australia by Aboriginal people, is believed to have ousted the devil from the mainland. Tasmanian devils are still common in some north, east, and central districts of Tasmania, where some farming practices (e.g., rangeland sheep grazing) provide an abundant source of food. - Mod.CP] ...............................cp/pg/jw
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 1 Aug 2003
From: Akira Goto <>
Source: The Lancet, Sat 2 Aug 2003, Vol. 362, No. 9381 [edited]
Japan: Transmission of Hepatitis E Virus from Wild Sika Deer to Humans
Zoonotic transmission of hepatitis E virus (HEV) has been suggested for various animals, on the basis of indirect evidence. Shuchin Tei and colleagues have identified potential zoonotic transmission of HEV from Japanese Sika deer (_Cervus nippon nippon_).
Over several weeks members of 2 [human] families developed hepatitis symptoms, but were negative for hepatitis A, B, and C viruses. Physicians discovered the patients had several times eaten raw meat from deer caught in the wild in the 7 weeks preceding the first hospital admission. Fortunately, leftover meat had been frozen and dated at the time of eating. HEV RNA sequences in the meat of one deer and most of the patients' samples were 100 percent identical. Shuchin Tei and colleagues conclude that this finding is direct evidence of zoonotic HEV transmission.
However, they believe consumption of substantial amounts of raw deer meat is necessary for transmission, since eating only a little did not lead to infection in other family members.
-- Akira Goto <>
[The Research Letter from Shuchin Tei, Naoto Kitajima, Kazuaki Takahashi, and Shunji Mishiro is entitled "Zoonotic transmission of hepatitis E virus from deer to human beings."
Hepatitis E virus is is a single-stranded positive-sense RNA virus which has characteristics (morphology and genome organization) in common with members of the family _Caliciviridae_, but it is sufficiently distinct phylogenetically to remain classified as a distinct unassigned genus. Hepatitis E virus has been associated with water-borne outbreaks of illness and sporadic cases of enterically transmitted acute hepatitis. Hepatitis E virus is considered to be endemic in tropical regions of Asia, Africa, and Central America, and non-pathogenic variants may be present globally. On the basis of immunological studies, related or identical hepatitis E viruses infect primates, swine, and other animals, to which now can be added Sika deer. - Mod.CP]
[Japan is a distinctly non-tropical country, so maybe wildlife from temperate region countries should be examined also. Sika deer are indigenous to Asia, but have been introduced into zoos & parks in many countries, notably Madagascar, South Africa, New Zealand & various Pacific island countries, USA (e.g. KY, MD, TX), UK & 7 other European countries, into which they have escaped and are breeding in the wild, and also hybridizing with indigenous deer in England & Texas. It would be interesting to discover whether those are also harboring hepatitis E virus, and whether their meat is eaten raw in those countries. - Mod.JW]
Patricia A. Doyle, PhD
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