Tag: infectious diseases

Fever of the Rat

By Claire Panosian Dunavan, UCLA School of Medicine | February 28, 2018 2:07 pm
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Beware, the biting rat. (Credit: Shutterstock)

Back in the 1980s, S.O.S. calls after midnight were common in the field of infectious disease. And as soon as my pager started to trill, I turned on my bedside lamp and dialed—often within thirty seconds. One night, I connected to an intern I’ll call Paddy. The background din quickly spelled “E.R.”

“Sorry to disturb you, Dr. P, but a woman woke with a rat on her face. Then the rat bit her lip.”

First, I expelled a disgusted “yecchh,” then I asked a question. “Was she drunk and passed out when it happened?” I asked, trying to picture the scene. Read More

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Horses and Humans, Bonded Through Botulism

By Claire Panosian Dunavan, UCLA School of Medicine | January 11, 2018 1:18 pm

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Last month, a 1,400-pound horse named John competed with speed and style at the World Series of Team Roping in Las Vegas.

Fourteen months earlier, John couldn’t even stand without the help of six handlers and a sling.

After qualifying for a 2016 competition, John was found down at his owner’s ranch near Sacramento, felled by botulism. Despite receiving an antidote, he battled paralysis for 26 days. For most of his stay in an intensive care unit, he lay on the floor of his stall. He eventually lost 250 pounds, but he never stopped breathing.

“He definitely has attitude,” says John’s owner and lifelong horseman, Doug Parker. “When I first bought him in 2014, I remember calling my wife and saying, ‘This horse has all the tools, but he’s still a little green.’ As it turned out he was a handful! Much more of a project than I realized.”

That attitude probably helped John to survive.

A long-feared disease of humans, food-borne botulism also sickens birds, chickens and four-footed mammals, but this deadly toxin has also forged a unique bond between horses and humans. Not only do horses model the disease’s worst paralytic features, healthy, hyper-immunized steeds provide a life-saving antitoxin that’s used to treat humans. And in recent years, the development of better diagnostic lab tests for horses has paralleled the adoption of better diagnostics for humans and potentially poisoned foods.

Since 1910, when a German researcher named Leuchs made the first equine-sourced antiserum, horses repeatedly immunized with C. botulinum toxin have helped save human lives. In 2013, the US Food and Drug Administration approved the first equine antitoxin targeting all botulism subtypes. This new heptavalent treatment for humans, which is currently stockpiled by the U.S. government, was hailed as a valuable addition to the nation’s “emergency medicine cabinet” not just for unlucky eaters but possible victims of a future bioterrorist attack. It’s all thanks to our equine companions.

A Potent Killer

Seven botulinum toxins, designated A through G, are currently known to block the release of acetylcholine, an essential neural junction transmitter. The toxins are produced when Clostridium botulinum spores, widely dispersed in nature, encounter perfect conditions for germination: the absence of oxygen, a non-acidic pH, just the right amount of moisture and a warmish temperature (the optimum varies by subtype). Most horses suffer type A or B botulism, which typically occurs after they ingest spoiled or moldy feed. But enormous bales of hay can also spell disaster.

Consider a large outbreak of botulism in Oregon, summarized in a 2010 article in the Journal of Veterinary Diagnostic Investigation. The herd ate from bales of damp, matted bluegrass strewn along a creek bank during an unusually hot February. “After the first horse showed signs of botulism, 20 horses (including the sentinel case) died within three days, and four more horses died over the next six days,” the authors grimly recounted.

Given the warming trends throughout much of the world, I put two and two together.

“Could climate change increase the risk of botulism in horses?” I asked first-author Dr. Amy Johnson, a large-animal internist, neurologist and botulism specialist at the University of Pennsylvania, where she also works in a botulism lab testing animal samples from all over the country.

“I can’t say, ‘No,’” she replied, “but other factors include the economy and the availability of farmland.”

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Parker and John competing in October. (Credit: Courtesy UC Davis)

Because huge, round bales of hay are cheap to produce they became increasingly popular following the 2009 economic crash, Johnson went on to explain. Shrinking acreage has compounded the problem by decreasing local production of hay baled as traditional squares.

In John’s case, however, warm, matted hay was not the culprit fueling the crisis, according to his owner. Parker is far more suspicious of a grain-plus-molasses “treat” fed to his 11-year old American quarter horse gelding. That same mix scooped from the bottom of a lidded can repeatedly re-filled with 50-pound bags of grain was also fed to two other horses from Parker’s herd who suffered botulism a few weeks before John went down.

The first victim—a “tough little horse,” in Parker’s words—survived for less than 24 hours before succumbing to her disease; the second horse was hospitalized for only three days, then returned home. In each case, the afflicted animals were given roughly a liter of antitoxin-containing plasma (which can arrest but does not reverse botulism) as soon as they reached the University of California, Davis veterinary hospital.

“Before last year, I never heard of botulism in horses,” Parker said. “Now I’m thinking a lot more horses have it than are ever reported or even seen by vets.” Parker also knows that, unlike UC Davis, many veterinarians do not keep antitoxin on hand, further delaying treatment and worsening outcomes.

In addition to the speedy administration of neutralizing antibodies, what determines an individual horse’s survival remains a topic of ongoing interest and concern among vets and owners alike. In Johnson’s mind, there’s no doubt that psychological factors contribute.

“It’s very scary for a horse not to be able to get up. Some wear themselves out just trying,” she says.

“John was obviously as amazing athlete with real spirit and grit,” echoed Dr. Gary Magdesian, a UC Davis equine specialist who has personally cared for 15 to 20 horses with botulism over the last two decades.

Spirit aside, no adult horse with full-blown respiratory failure has yet been reported to beat botulism. Unlike in humans, in full-size equines, mechanical ventilation is simply too laborious, costly, and fraught with complications. On the other hand, what can make all the difference is a quick diagnosis along with the prompt infusion of antitoxin (the best commercial preparation currently available for horses covers types A through C) plus experienced supportive care.

Back to Roping

Once John was back on his feet, Parker gave him a couple of months to recover, then took him to Arizona for a roping tryout. “It felt like he was ready, but he wasn’t.” At that point, the rancher removed John’s shoes and put him out to pasture to gain more weight. “I’m not going to bring him back until he has two big old rump-cheeks,” he told himself.

The decision clearly paid off. Although Parker didn’t win prize money in Las Vegas, it wasn’t because of John. “I missed three steers I should have roped and broke a barrier,” he shrugged. “John was in as good a shape as ever.”

The final question—whether rates of equine botulism are currently climbing—is impossible to answer. Unlike their riders, there is still no mandatory reporting of horses with botulism.

CATEGORIZED UNDER: Living World, Top Posts

Climate Change, Disease and the Fall of Rome

By Kyle Harper | December 15, 2017 11:01 am
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This painting (circa 1836) titled “Destruction” is one painting depicting in a five part series by Thomas Cole called “The Course of an Empire.” (Credit: Wikimedia Commons)

At some time or another, every historian of Rome has been asked to say where we are, today, on Rome’s cycle of decline. Historians might squirm at such attempts to use the past but, even if history does not repeat itself, nor come packaged into moral lessons, it can deepen our sense of what it means to be human and how fragile our societies are. Read More

If Your Pet Has This Tapeworm, It Could Kill You

By Emily J. Jenkins, University of Saskatchewan | December 4, 2017 12:35 pm
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A coyote cools off in the shade of a leafy suburb. Wildlife interactions with pets and humans can transfer disease, including the tapeworm Echinococcus multilocularis. (Winston Wong/flickr)

Dogs are sending us an early warning signal about the spread of a potentially deadly tapeworm in North America.

The tapeworm, Echinococcus multilocularis, is normally found in rodents and other wild animals, including coyotes and foxes, but can spill over into cats and dogs — and even humans. Read More

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Malaria During Pregnancy Could Bolster Babies’ Immunity

By Kim Smuga-Otto | June 5, 2017 3:27 pm
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A mother and baby from the village of Pomerini, Tanzania. It’s estimated that the disease kills 60,000 to 80,000 people there annually. (Credit: Franco Valpato/Shutterstock)

You have a bit of your mother in you, literally.

When scientists performed biopsies of young adults’ organs, they’ve found maternal cells embedded in hearts, kidneys, and liver. This phenomenon, called microchimerism, is caused by a small number of cells passing through the placenta during pregnancy. The transfer goes both ways, and scientists think it’s like a meet-and-greet between mom and fetus, preventing their immune systems from treating each other’s cells as dangerous invaders. But that doesn’t explain why these cells stick around long after birth. Read More

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Flesh-Eating Bacteria Like It Hot

By Hannah Gavin | September 30, 2016 12:05 pm
Vibrio vulnificus bacteria. (Credit: Wikimedia Commons)

Vibrio vulnificus bacteria. (Credit: Wikimedia Commons)

It’s spring, and I’m attending a luxurious seafood banquet. Platters of shellfish fill the tables: crab with limbs akimbo; shrimp ready to be peeled; miniature lobster-like langostino peering at my dinner plate as if knowing their fate. Raw oysters sit in the center of the platter, piled absurdly high and shimmering luminescent on the half shell.

Until now, I’ve never eaten a raw oyster. I apply a generous squirt of lemon juice and watch the white-grey flesh ripple ominously in reply. Tilting my head back, I down the shell’s contents in one shot of citrusy ocean. The gelatinous solid slides down my throat largely unchewed as I submit a silent prayer to the gods of food safety, asking not to become the subject of an ironic headline:

“Research scientist studying bacterium found in raw oysters falls ill after eating…a raw oyster.”

Thankfully, I walked away from the banquet without encountering Vibrio vulnificus, the bacterial subject of my Ph.D. Much as I want to be an academic expert on V. vulnificus, there are aspects of the microbe I hope never to attest to first-hand. But as the planet’s oceans heat up, the odds of a potentially fatal rendezvous will continue rise along with the temperature. Read More

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STDs Might Have Driven Us to Embrace Monogamy

By Rob Knell, Queen Mary University of London | April 13, 2016 2:17 pm
monogamy

(Credit: Ivan Galashchuk/Shutterstock)

Exactly why so many humans choose monogamous pair bonds over juggling multiple partners has long been a mystery to scientists. After all, having several partners at the same time should lead to more offspring — an outcome you’d think evolution would favor. Now a new study has linked the phenomenon to sexually transmitted diseases, arguing that monogamy could have evolved because it offered protection against the threat of infection.

Monogamy is, of course, the norm in Western societies. But there are many cultures where a husband can have more than one wife (polygyny) or, less commonly, a wife can have more than one husband (polyandry). This diversity of human mating systems is also hard to explain. What we do know, however, is that many hunter-gatherer societies, living in small groups, were most often polygynous (and many remaining groups still are). But with the rise of agriculture, societies tended to become more complex — and less polygynous. In the most strictly monogamous societies, there was often a social punishment for polygynists, either informally or, as in many modern societies, through a legal system. Read More

What Lessons Will We Learn From Zika?

By Carl Engelking | February 5, 2016 6:09 pm
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A female Aedes aegypti mosquito. (Credit: U.S. Department of Agriculture/Flickr)

Zika virus caught the world off guard, but it shouldn’t have.

The rapid spread of the mosquito-borne virus, and its possible connection to birth defects and neurological disorders, compelled the World Health Organization on Monday to declare an international public health emergency. But by that time 1.5 million Brazilians had already caught the virus, and it had spread to 24 countries in the Western Hemisphere. The current tally from the Centers for Disease Control and Prevention indicates 30 countries are now reporting active transmission.

“It seems like we are always behind,” says Jorge Osorio, a professor of infectious diseases at the University of Wisconsin-Madison. Osorio returned to the United States on Friday after a research stint in Colombia, where the total of confirmed Zika cases is second only to Brazil. “We knew it was a matter of time before this would happen.”

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Countries and territories with active Zika virus transmission. (Credit: CDC/NCEZID/DVBD)

There’s no doubt that a rapid global response — like what’s currently underway — is needed, but Zika’s transformation from a sleeping virus to a global crisis is all too familiar. Since the 1970s, global re-emergence of mosquito-borne infectious diseases has only accelerated. In 2001, global cases of dengue fever skyrocketed. In 2004, chikungunya re-emerged in East Africa and spread worldwide. But with every new outbreak, a recurring flaw in the approach toward infectious disease control is exposed: We’re consistently reactive.

“It’s sort of human nature. We react to the thing that’s on fire, but we aren’t so good at prevention,” says David Katz, a certified board specialist in public health and founding director of Yale University’s Yale-Griffin Prevention Research Center. “We neglect the factors that produce emerging infectious disease, and in the blink of an eye we have a global crisis on our hands.”

A Period of Apathy

By the late 1960s humanity was winning its war with malaria, yellow fever, dengue and a host of other diseases. Proactive, aggressive eradication efforts eliminated the Aedes aegypti mosquito — the primary carrier of infectious diseases — in 23 countries. But our declaration of victory was specious.

Duane Gubler, a professor of emerging infectious diseases at Duke-NUS Medical School in Singapore, noted in a 2011 review that our comfort in victory kicked off a period of “increasing apathy and complacency” toward controlling infectious diseases. A new, more reactive paradigm of surveillance and emergency response was adopted for disease control, and resources shifted to other diseases.

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A look at how Aedes aegypti populations rebounded in tropical Americas from 1930 to 2011. (Credit: Duane Gubler, “Dengue, Urbanization and Globalization: The Unholy Trinity of the 21st Century,” Tropical Medicine and Health, Vol. 39, No. 4 Supplement, 2011, pp. 3-11)

In the four decades that followed, unprecedented population growth occurred around the world, and more people converged in crowded urban centers. Mosquitoes that once spread diseases in remote, less-populated locales had millions more human hosts to bite and infect in confined areas. On top of that, advances in global transportation made the world smaller and further enhanced the ability of viruses to expand their reach. Today, a respond-to-an-emergency approach can’t keep up with the ability of viruses to mutate and spread.

“We live in a crisis-oriented society. But this has been going on for the better part of 40 years as we’ve seen these global pandemics of infectious diseases spread,” says Gubler. “We wait for them to occur.”

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The emergence of the dengue in the Americas was associated with the introduction of new variations of the virus. (Credit: DengueNet 2007 data provisional via Duane Gubler, “Dengue, Urbanization and Globalization: The Unholy Trinity of the 21st Century,” Tropical Medicine and Health, Vol. 39, No. 4 Supplement, 2011, pp. 3-11)

Writing Was on the Wall

Infectious disease researchers could see Zika’s warning signs long before the outbreak captured headlines. The virus was isolated in 1947 from rhesus monkeys in Uganda. Only sporadic human Zika infections were reported since its initial discovery, and its clinical presentation didn’t sound alarms. Oftentimes, infected people wouldn’t know Zika was in their system. For that reason, the virus didn’t garner much attention or warrant funding for research.

“In the United States, research for all science and infectious diseases has been at historic lows, so to get funding for Zika virus, which wasn’t causing many infections, was nearly impossible,” says Matthew Aliota, a research scientist at the UW-Madison School of Veterinary Medicine.

It wasn’t until 2007 that a Zika epidemic swept through Yap Island in the Federated States of Micronesia. A larger epidemic followed in French Polynesia in 2013-14. In May 2015, the Pan American Health Organization issued an alert about the transmission of Zika virus in Brazil. And in July, Gubler sounded the warning in an issue of The Lancet.

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A transmission electron micrograph of Zika virus. (Credit: Cynthia Goldsmith/CDC)

“We essentially predicted this months ago, and said it would follow in the footsteps of chikungunya because it has the same epidemiology,” says Gubler. “Part of our problem is that we have a mentality of looking at these viruses, including a lot of virologists, as monolithic species. These viruses change genetically, and those changes affect expression.”

Today, a virus that was largely ignored is now affecting human health in ways we didn’t anticipate. In other words, a virus that’s lying dormant doesn’t make it less of a threat to world populations. And with half the world’s population living in areas susceptible to infectious diseases, a virus that’s gone quiet doesn’t mean it won’t come roaring back.

“Yellow fever is another virus that’s sitting in the wings. It still exists in West Africa, but it’s been relegated for the past 60 years,” says Gubler. “If, or when, it starts causing trouble, it will make all of these other outbreaks pale by comparison.”

Preventing the Next Outbreak

That’s why Gubler, Osorio, Katz and others advocate for going on the offensive to strike viruses before they spiral out of control — even benign viruses. With adequate resources, vaccine development could be accelerated. Mosquito populations could be kept in check. Researchers across scientific disciplines could collaborate to build ways to predict future hotspots for outbreaks and focus energies there.

“You need to rebuild public health infrastructure in endemic countries and develop the lab capacity to support a surveillance system to give you some predictive capability,” says Gubler.That requires investment, dedication and some bit of faith on the part of policymakers that this is money well spent.”

Osorio and Aliota are working in Colombia to build more accurate laboratory diagnoses of Zika, dengue and chikungunya. The other focus of their research is to track the way Zika and viruses like it evolve and adapt in their hosts. Their research has shown that Zika split into two distinct lineages, African and Asian. The strain they’re seeing in Colombia can be traced back to the strain that existed in the 2013-14 outbreak in French Polynesia. But their work has a larger aim: predicting how viruses will mutate to get ahead of the next outbreak.

“I’m trying to be more predictive using lab studies and experimental evolution in the lab to be more proactive,” says Aliota. “It’s idealistic thinking, but we’re working to predict the evolvability and adaptability of certain viruses.”

Building a more thorough global network of early detection centers around the world is also essential for pivoting to a proactive approach to infectious disease. Expanding the reach of organizations like the Global Virus Network, which is composed of research centers around the world that focus on viral causes of human disease to prepare for novel pandemic threats, could provide enough warning stay ahead. A robust, global virus detection system could operate similarly to the global array of earthquake-detecting instruments that give advance notice of a potential disaster.

“We must continue to create those centers around the world, and ensure they are funded and equipped with people who are well trained to do this,” says Osorio. “Early indication is important, and it gives us the ability to take measures right away.”

Interdisciplinary Approach

“We need to look at culture, epidemiology, economics and ecology at a local level and develop strategies from there,” says Gubler, who helped form the Partnership for Dengue Control, which brings health experts together to do that.

Overall, infectious disease researchers are pushing toward a more interdisciplinary approach to predict outbreaks. Jonathan Patz, director of the Global Health Institute at UW-Madison, is doing research to connect the dots between climate change and global health, offering a glimpse into the ways differing scientific fields can combine to build a proactive approach to mosquito-borne disease. His research has revealed a link between dramatic climactic shifts and the occurrence of viral outbreaks.

“Extreme drought conditions tend to drive the proliferation of Aedes aegypti. Epidemics of Zika, dengue and chikungunya have been preceded by drought,” says Patz. “This year, the el Nino event is looking like the strongest on record. During el Nino, northeastern brazil is generally affected with drought.”

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NOAA declared 2015 as the world’s hottest year on record. In the same year northern Brazil, Colombia, parts of Venezuela, Peru and Ecuador experienced record heat.

Patz notes there are myriad other variables that shift weather patterns and the spread of disease. But, generally speaking, he is finding that drought is a contributing factor. Patz’s work reflects a larger shift toward looking beyond the infectious agent and building a broader recognition of factors that are in play. 

“It’s getting much better in terms of interdisciplinary focus,” says Aliota. “I never thought, when I first got into the hard sciences, that I would be talking to geographers, anthropologists and the other disciplines in my work.”

Of course, controlling the populations of A. aegypti, the source of the problem, is also a key area of research. Methods of population control, and wider access to mosquito nets and repellant in poor countries are essential. There’s also emerging interest in research to genetically modify mosquitoes. The research could limit their ability to breed — or wipe them out completely.

“Mosquito control has been left wanting for over 40 years, and that’s catching up with us,” says Gubler.

In It Together

If there’s any silver lining from the surge in outbreaks, it’s that it brings into sharp focus the sheer connectedness of humanity. Zika, dengue and chikungunya don’t respect political borders. Outbreaks are forcing us to break long-standing lines of division and embrace the fact that we are one species.

“Zika does not give a damn about whether you are Muslim, Jewish or Christian,” says Katz. “The world is small, and there is no ‘over there anymore.’ We’re all in the same petri dish. I think that shift in thinking is fundamental to our preparedness.”

CATEGORIZED UNDER: Health & Medicine, Top Posts

Ebola’s Possible Future as an Endemic Disease

By Kari Lydersen | January 19, 2015 11:36 am

Last fall as the Ebola epidemic continued unabated, experts started discussing something that had never before been bandied about: the idea of Ebola becoming endemic in parts of West Africa. Endemic diseases, like malaria and Lassa fever in that region of Africa, are constant presences. Instead of surfacing periodically, as it always has before now, Ebola in an endemic form would persist in the human population, at low levels of transmission, indefinitely.

The debate was stoked by a paper written by the World Health Organization (WHO) Ebola Response Team and published in October in the New England Journal of Medicine. The sentence that grabbed the world’s attention was saved till near the very end: “For the medium term, at least, we must therefore face the possibility that EVD [Ebola virus] will become endemic among the human population of West Africa, a prospect that has never previously been contemplated.”

What would it mean exactly for Ebola to become endemic, and how would it change things?

Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

Ebola Teams Need Better Cultural Understanding, Anthropologists Say

By Kari Lydersen | December 9, 2014 8:30 am

A defining feature of this Ebola epidemic has been the significant resistance of some of the affected communities to treatment and prevention measures by foreign aid workers and their own governments. Many local people, suspicious and fearful, have refused to go to treatment centers or turn over bodies for safe burial, and whole communities have prohibited the entry of doctors and health teams.

As the months have gone by that resistance has been less reported upon, and there are signs that it may be lessening. In the Forest Region of Guinea, where the Ebola epidemic started, foreign staff previously faced roadblocks, stone-throwing and violent attacks. But in the last few weeks, as the New York Times has reported, locals have opened up the literal and figurative barricades around their villages and sought outside help.

Still, the friction continues to shape the spread of the disease. Doctors Without Borders’ December briefing paper [pdf] calls the situation in Guinea “alarming,” with 25 percent more cases reported in November than October and many areas where there is “still a great deal of resistance towards Ebola response” and their teams are “not welcome.”

The solution, some say, is to reevaluate treatment and prevention tactics with the benefit of an anthropological perspective. That was the call delivered last week by a meeting of the American Anthropological Association in Washington D.C. If international staff had approached the epidemic from day one with more understanding of cultural, historical and political context, attendees said, local traditions and community leaders could have become assets rather than obstacles in the fight against Ebola.

The American Anthropological Association is asking for anthropologists to become more involved in the global Ebola response. They have started the Ebola Emergency Response Initiative to connect anthropologists who are already working in or experienced with West Africa, and to build structures and programs that help more anthropologists spend time directly involved in the Ebola response on the ground.

“We’ve worked in these places and we’re watching our friends die,” said University of Florida professor Sharon Abramowitz, one of the founders of the initiative.

Abramowitz points out that the anthropologists involved in the initiative have a total of 300 years of ethnographic experience in the affected West African nations – experience which could help medical scientists both understand and respond to the epidemic.

Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
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