New Fungus Strain Killing People and Animals in Northwest
By Linda Moulton Howe
"Everybody was taken completely by surprise because there
had been no cases prior to 1999 of Cryptococcus gattii in the
Northern Hemisphere and suddenly, there were a whole
series of cases occurring in both humans and animals."
Joseph Heitman, M. D., Molecular Geneticist, Duke Univ. Med. Center
Cryptococcus gattii basidia and spores. Photomicrograph provided by Joseph
Heitman, M. D. and Ph.D., Molecular Geneticist, Duke University Medical Center.
May 27, 2010 Durham, North Carolina – Recently Web MD and other Internet medical sites have featured articles with headlines such as, "About 10 People Have Reportedly Died in Northwestern U.S. After Infection with C. Gatti. [sic]" Cryptococcus gattii is a soil and plant fungus species usually found in South America, Australia, Africa and New Guinea. That particular fungus was not discovered in North America before 1999 when clinicians on the island of Vancouver, B. C., Canada, in the southeastern cities of Victoria and Nanaimo, confirmed emergency room patients with pneumonia and meningitis were infected with C. gattii fungus.
About the same time, veterinarians in the region were also treating dogs, cats and other animals with breathing problems that turned out also to be from C. gattii fungus infections. Then in January 2006, the first American case of human C. gattii fungus infection was confirmed in a patient who lived in the San Juan Islands of Puget Sound, Washington. Canada has now reported a total of 220 patients and 19 deaths attributed to the C. gattii fungus. That's a 10% death rate. In the United States, the Centers for Disease Control (CDC) has identified 50 cases in Washington State, Oregon and Idaho with 10 deaths. That's a 20% death rate.
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So the combined number of Canadian and U. S. cases of C. gattii fungus infection is now 270 cases with 29 deaths in a decade. Recently I talked with the head of a Duke University Medical Center research team that has gone to the Vancouver and northwestern United States to study the soil, plants and trees in which Cryptococcus gattii fungi now seem to be thriving and spreading. He is Joseph Heitman, M. D. and Ph.D., Chair and Professor in the Department of Molecular Genetics and Microbiology at the Duke University Medical Center in Durham, North Carolina. I asked Dr. Heitman if he and his medical team were surprised to learn that the Southern Hemisphere fungi was making people and animals sick in the Northern Hemisphere climate of Vancouver, Washington State and Oregon.
Interview:
Joseph Heitman, M.D. and Ph.D., Chair, Department of Molecular Genetics
and Microbiology; James B. Duke Professor, Departments of Molecular
Genetics and Microbiology (MGM), Pharmacology and Cancer Biology, and
Medicine; Duke University Medical Center, Durham, NC.
JH: Joseph Heitman, M. D. and Ph.D., Chair and Professor, Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina: "Everybody was taken completely by surprise because there had been no cases prior to 1999 of Cryptococcus gattii in the Northern Hemisphere and suddenly, there were a whole series of cases occurring in both humans and animals. Fungal outbreaks are also very rare and uncommon, so this was sort of a unique occurrence. And everyone was taken very much by surprise and one of the first questions that everyone asked was: Where is it coming from? How are they being exposed?
LMH: But the fact that it surprised you and other medical experts says something has shifted in the environment that is allowing this fungi to attack people and animals?
JH: Certainly there is something that we think is causing the gattii spread to increase in its distribution in the environment. I don’t think one can say whether that’s global warming. I’m not sure that one
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can say it’s due to the introduction of new pesticides. We don’t really know. We do know though that we can document that the organism can be carried on car tires great distances, on peoples’ shoes, that it can be found in the water, that porpoises that sun off the coast of Vancouver Island or Puget Sound can become infected with the fungi and die of fulminate pneumonia. There have been increasing numbers of cases of animals in the area – dogs and cats, elk, alpaca, sheep – a very broad range of animals being infected. But still, the numbers are relatively low and I would say it still remains an uncommon or rare cause of infection.
LMH: But a mystery.
JH: Some aspects of it are a mystery. There might be an unrecognized number of similar cases within the United States of people who have traveled to Seattle or Portland or Vancouver. I don’t think there will be a lot of cases. But there are at least six examples that have been published already of travelers to the region who almost certainly acquired their infections in the Pacific Northwest and then went somewhere else very far from it.
It’s also possible it will spread in the environment, but not adjacent geographically. It might be that it pops up somewhere else in Canada or the United States. So we are involved in surveillance of cases that are occurring throughout the U. S. The CDC in Atlanta also has a very active working group involving the State Health Departments in Washington State, Oregon, California, Idaho, Montana, Nevada and Alaska.
C. gattii Symptoms
JH: This is a fungus we are exposed to by breathing it in, by inhaling it from the environment. So, the first place it causes infection is in the lungs. And it can also spread to the brain and central nervous system to cause meningitis. So the fungus causes either a pneumonia or meningitis.
LMH: Meningitis is what causes inflammation on the surface of the brain between the skull and brain and causes terrible headaches?
JH: That’s right. So, this can cause meningitis or can infect the brain itself. The medical term would be Meningoencephalitis.
[ Editor's Note: Wikipedia - Meningoencephalitis is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain. ]
JH: But you’re right, C. gattii is very commonly associated with headache and also with fevers. These can be pretty severe illnesses, so associated with night sweats, fatigue, severe weight loss. Some of the other symptoms of meningitis are visual changes or neck pain.
The pneumonia symptoms are typically described as a very severe cough lasting weeks to months and associated with shortness of breath and chest pain.
LMH: Does anybody so far have any idea about why it would translate as symptoms of meningitis in some people and as pneumonia is others?
JH: That’s a very good question. Some patients seem to have fairly restricted lung infection. Other people seem to have more meningitis. Some people have both. So, that’s a very good question why it might present differently in different patients. It might have to do with the amount of the organism to
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which people are exposed. It might also have to do with patient risk factors. And it might also have to do with human genetics to some extent. We are all somewhat different from each other.
How Does C. gattii Kill?
LMH: Why have the people who have died – died?
JH: With many, many infectious diseases, there is a risk of death. It might be attributable to pneumonia, so it would be a failure of lung function. It might be attributable to the meningitis. And people can die even with appropriate therapy. Part of that relates to whether there is enough immune function in a patient to work together with anti-fungal drugs to fight off the infection.
We have a lot of evidence that sexual reproduction is occurring in the Cryptococcus gattii population and we think that has given rise to new genotypes that are the cause of the outbreak.
LMH: Meaning sexual reproduction in the fungi produces offspring that are mutated into something that is slightly different?
JH: Sexual reproduction describes the process whereby two different genetic isolates come together and undergo sexual reproduction and have progeny, or offspring. Those offspring then have a genetic makeup that is combined – half the genes from one parent and have the genes from the other parent. So, it is not a subtle mutagenic process. It’s a reshuffling of the entire genome from the two parents, giving rise to very different kinds of offspring. So, that can certainly create a very different kind of isolate.
The other thing is that sexual reproduction of fungi is what produces the spores that we inhale. So, we think that sexual reproduction might be giving rise to the particles that are disbursed in the air that we are exposed to.
Will C. gattii Fungus Keep Spreading?
LMH: The fungus has caused disease in Vancouver Island in Canada, parts of Washington, Oregon, Northern California and Idaho. How likely do you think it is that this fungus will continue spreading throughout other Canadian provinces and the United States?
JH: Since January 2007 to now (May 2010), the known reported U. S. cases had occurred in Washington State and Oregon State. However, the CDC set up a working group that has identified one case in Idaho and three patients in northern California. So, our concern is that it will continue to spread geographically. We know that the fungus is in the air. It might even be in air currents moving the fungus around. We know it can survive for a long time in both fresh water and salt water, so even movement of the fungus through water is possible.
LMH: Is there any evidence of C. gattii transmission directly from animals to humans or humans to animals?
JH: That’s a very, very good question. Certainly in the context of this outbreak, and Cryptococcus globally, there isn’t any evidence for human-to-human transmission or animal-to-human transmission. Someone who has a severe cough with Cryptococcus gattii, they are not going to infect anyone around them. It’s not communicable in that way.
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Since this 2009 map was produced, the CDC has confirmed at least one C. gattii infection
in Idaho and three more in northern California. Map © 2009 by Europa Technologies.
LMH: So the fungus itself has to be breathed into the lungs of humans or animals?
JH: That’s right. So, the exposure for every animal and every human that’s infected, we think it’s a unique encounter in the environment and we think it is attributable to inhaling spores that are in the air.
Lethal Fungi Increasing On Earth Now?
LMH: If I understand then, it means that something in the environment is making it more conducive for various fungi to have sexual reproduction together that produces different offspring that suddenly might be causing diseases in animals and humans that were not there before?
JH: Right.
LMH: Why is it that from 2006 to 2010 and counting with Chytrid fungus killing amphibians, Geomyces destructans killing bats and honey bees mysteriously disappearing that the fungal world suddenly seems more deadly?
JH: Excellent question, Linda, and I actually just came back from meeting one of my clinical colleagues here who is heading to an Institute of Medicine-sponsored meeting in a couple of weeks. There are going to be four presentations on emerging infectious diseases. One on the Cryptococcus gattii outbreak we’ve been talking about. One of the other presentations will be about the Chytrid that you mentioned that is causing amphibian declines and extinctions around the globe.
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Cryptococcus gattii spores. Photomicrograph provided by Joseph Heitman,
M. D. and Ph.D., Molecular Geneticist, Duke University Medical Center.
JH: One of the other talks will be about the Geomyces destructans fungus that is causing the white-nose bat syndrome that has just emerged since 2006.
Then in another week at the American Society for Microbiology at a general meeting in San Diego, there is going to be a symposium focused on microbes and the risk of extinctions. Those topics are going to be on bat and beehive collapse, bat white-nose syndrome, and the Chytrid amphibian declines. But I think you are quite right that these are three very different areas where fungal pathogens have emerged. There has been a lot of speculation about where these came from. I’m most familiar with the studies of the Chytrid and amphibian decline.
The role of this Chytrid fungus in contemporary extinction events is what we see happening in a variety of frog and amphibian species. It’s really pretty sobering that it’s a fungus that is causing extinction events on Earth now. It’s not a bacteria. It’s not a virus. It’s not a parasite. It’s a fungus and it’s a fungus from probably one of the most obscure groups of fungi that have ever been studied – this basal group of aquatic fungi.
In the case of one of the fungi genotypes circulating in Oregon that we’ve discovered, it’s the only place we have found it in the world and it does seem like a new type of isolate has emerged there. It is different from the isolate that has been causing the outbreak on Vancouver Island and Canada and in Washington State. So, in some senses, it is an outbreak within an outbreak. We’re interested in how did this new isolate suddenly start occurring from 2006 onward in Oregon? Is that isolate in addition to the one on Vancouver Island? Are the fungi moving further north? Further south? There’s a well-documented risk now for travelers to the endemic region such as European tourists who visited Vancouver or other areas in the endemic region and then returned to Switzerland or Denmark or The Netherlands and became sick with Cryptococcus gattii infection."
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More Information: For further information about fungal threats, please see Earthfiles Archive for other reports such as those listed below:
White-Nose Fungus Geomyces destructans Attacks Bats:
• 05/20/2010 — Fungus in White-Nose Bat Deaths Has Spread Rapidly to Missouri and Oklahoma
• 03/25/2010 — Bat Die-offs Spread to 11 States and Scientists Call It "Crisis"
• 06/26/2009 — Mysterious Northeast Bat Deaths Now in 9 States and Headed Toward Kentucky
• 02/26/2009 — Unprecedented Northeast Bat Die-off Spreading Rapidly
• 02/29/2008 — Mysterious Bat Deaths in New York, Vermont and Massachusetts
Amphibian Decline and Extinctions Caused by Chytrid Fungus:
• 11/20/2009 — Red List of Earth Life Facing Extinction Keeps Growing
• 06/26/2009 — Mysterious Northeast Bat Deaths Now in 9 States and Headed Toward Kentucky
• 02/26/2009 — Unprecedented Northeast Bat Die-off Spreading Rapidly
• 08/15/2008 — Amphibian Warning Bell of Mass Extinctions
• 01/18/2008 — Amphibians Dying Out At Alarming Rate
• 02/23/2007 — Scientists Hope "Amphibian Arks" Can Save Frogs and Toads
• 09/09/2006 — Methane - Another Threat in Global Warming
• 08/26/2005 — What Is Killing Amphibians Around the World?
Nosema ceranae Fungus Attacking Honey Bees:
• 05/05/2010 — Updated: U. S. Honey Bee Industry Struggles with 34% Colonies Loss
• 02/18/2010 — U. S. Honey Bee Deaths Increase Again
• 01/28/2010 — Airport Body Scanners - How Safe Is The Terahertz Radiation?
• 06/26/2009 — Mysterious Northeast Bat Deaths Now in 9 States and Headed Toward Kentucky
• 03/30/2009 — European Honey Bee Decline Continues While Aggressive Africanized Honey Bees Attack in Southern U. S.
• 12/21/2008 — Mystery of Missing East Coast Acorns
• 09/26/2008 — NRDC Sues EPA for Honey Bee Lab Data and EPA Approves Another Bee-Killing Pesticide
• 09/05/2008 — Growing Concern about Electromagnetic Pollution and Cell Phones
• 08/31/2008 — Honey Bees Not Healthy in U. S. or U. K.
• 05/06/2008 — Viewer Comments on Decatur, Alabama, White Sphere Incident
• 05/06/2008 — What Are the Strange "Pearls" in Google Map Images?
• 05/02/2008 — 3-Foot-Diameter Sphere Retrieved By Ambulance in Decatur, Alabama
• 04/10/2008 — Honey Bee Collapse Now Worse on West Coast
• 10/13/2007 — Now Bumblebees Are Disappearing, Too.
• 09/26/2007 — North American Honey Bees Still Weak
• 09/18/2007 — E. coli and Salmonella Continue to Threaten American Bagged Salad Greens
• 09/07/2007 — Honey Bee DNA Study Finds Australian Virus in Colony Collapse Disorder
• 07/11/2007 — Mystery of Night Shining Clouds - Another Global Warming Change?
• 05/29/2007 — Deadly VHS Fish Virus Has Spread to Lake Michigan
Websites:
Department of Molecular Genetics and Microbiology: http://mgm.duke.edu/news/heitman_5.html
Cryptococcus gattii Loves Inositol Sugar: http://mgm.duke.edu/news/heitman_4.htm
Credits: Copyright © 1999 - 2010 by Linda Moulton Howe. All Rights Reserved.
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