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Australia’s Plague of Mice Is Devastating and Could Get a Lot Worse



Australia’s southern and eastern agricultural regions are deep in the thick of a months-long plague of mice that has destroyed crops and overwhelmed farmers. The infestation comes after years of drought, devastating wildfires and a period of heavy rain that boosted plant growth, creating ideal conditions for the hungry rodents to reproduce exponentially. Now farms and fields are overrun with swarms of mice that have taken up residence in the walls of barns and homes.

Mice first appeared in Australia with the arrival of British colonists in 1788. These days the continent sees populations boom and die off every few years. But many farmers say this year’s infestation is the worst they have ever seen, and there is no sign that it is letting up soon. “The prolonged rain and the bumper crop of food means that the rodents have lots to eat for a very long time,” says Steven Belmain, an ecologist at the Natural Resources Institute at the University of Greenwich in England, who studies rodents’ roles as agricultural pests and disease vectors. Scientific American spoke with Belmain about how climate change has influenced the infestation in Australia, whether other parts of the world could see similar outbreaks and if the present one could lead to the spread of illness.

[An edited transcript of the interview follows.]

Is the current outbreak of mice in Australia surprising?

When the rain started quite severely, a lot of the scientists had an idea we were going to be in for a mouse plague. It wasn’t a great surprise to many of the experts because they have had these outbreaks going back more than 100 years in Australia. They’re periodic, and they are always sort of related to these bumper years of rainfall and wheat production. This one is quite large, but I think that is because the rainfall was particularly widespread. It’s predictable in the very short term–there is no great pattern to them. You can’t say once a decade or once every five years this happens; it really is down to the cycles of the rains.

But some scientists are worried this outbreak might extend longer than usual, right?

This year it’s been a fairly mild and wet summer, so that means vegetation is continuing to grow [into Australia’s winter]. A lot of the mice might survive until next year, and [then] there will be a better starting population. So next year could be even worse, depending on what happens in the next couple of months or so. Or it may just die out–that is very much down to what happens with rain. It’s still kind of early days to figure out which way it’s going to go.

What impact might this infestation have beyond agriculture? Is there risk of disease spread?

In times of pandemic, we become more sensitive to the fact that rodents are great disease transmitters. More than 60 different diseases are transmitted by rodents. But usually, when you have these massive explosions, the population is just expanding so quickly that it’s difficult for a disease to establish because it’s kind of a boom-and-bust situation. A lot of problems with disease tend to be much more chronic.

But in other parts of the world, particularly in parts of Africa and Asia where the disease burden is higher, they are worried about things such as leptospirosis and plague [the disease caused by Yersinia pestis], which follow the population cycles. So bigger population events do lead to increased disease transmission in some cases, but I don’t think that applies really very much to Australia.

What efforts are there to mitigate this infestation?

What they’re continuing to do is baiting with zinc phosphide. It’s a coating, what we call an acute poison. And when the animal eats it, it releases gas into their digestive system and causes them to die. Not a very nice way to die if you’re worried about humaneness. The alternatives are anticoagulant poisons, but those accumulate in the environment. So there are good reasons not to use those, particularly where you’re spreading [them] around by airplane. The advantage of zinc phosphide is that it doesn’t accumulate in the environment, so the danger of other animals having long-term exposure to some poison is minimized. But of course, when you put it out there, everything that eats it is going to die, so this could be a danger to pets.

It’s more about human behavior than about biology–people just have to do something. I don’t think the evidence of its effectiveness is very good. A lot of [what is required is] quite early prevention. And what has happened this year is: people [have been] somewhat taken by surprise, because they forget about the past. Some of the activity to manage [the mouse outbreak] has been delayed to some extent.

How has climate change impacted the current infestation? And how will it impact future population explosions?

Through the past decade or so, there’s been a very severe drought [in Australia]. The mouse population pretty much disappeared, and people thought, “Oh, no more mouse problems!” And that did have a knock-on impact into research and development because a lot of people said, “Oh, we don’t need all these mouse experts anymore.” Funding to that area of research kind of dried up. And so there has been a sort of “Okay, now we’ve got a problem again….” And there is no easy solution. It is driven by rainfall, and trying to manage that process is really quite difficult.

Are these outbreaks something that we just have to live with? Are they going to become more frequent? You could argue [that] with climate change, Australia is going to become much more of a drought-stricken country. Or perhaps these rainfall events are going to just be coming through much more severely, which would then drive the outbreaks to become more frequent. In some other parts of the world, we definitely know that climate change is going to have a bigger impact, particularly where you have extreme weather events such as cyclones and hurricanes.

Should the U.S. expect to experience anything similar to what we are seeing in Australia?

In the Southwest of the U.S., there are gophers, which do go through some outbreak scenarios, and their populations do cycle with El Nino or La Nina. The other rodents [in the U.S.] don’t really seem to go through those sort of boom-and-bust cycles–there’s just not as dramatic a change in the amount of rainfall coming. But a lot of the rodents in the U.S. are still cyclical on a seasonal basis, and they are clearly responding to agricultural production. If you go through the massive interior where there’s maize production, you will get increased numbers of rodents as the season progresses. But then there’s an end of the season. If we were going to have outbreaks [in the U.S.], we would have noticed it by now.

Is there a way to stop these periodic rodent outbreaks?

In Australia, if they stopped producing wheat throughout the wheat belt, there’d be no more outbreaks. But if you’re going to try to convince the Australian government to [do that], everyone [will] just laugh at you. Growing food is much more important. You could easily think of ways of taking the food away from the rodents, but then we need the food, too. Unfortunately, it’s a system we are going to be stuck with, so we might get better at managing it.

We can think about ways of growing crops much more synchronously. Asynchronous planting exacerbates problems. In some parts of Asia, if everyone grows the rice at the same time, then you have clear fallow periods that disrupt the population outbreaks. In Australia, I think, not all the wheat is necessarily grown at the same time. You could try to coordinate that a little bit better. But again, economics comes into this. When everything is synchronous, it may be good biologically, but economically, it means you need all your tractors ready at the same time to do the harvesting. Would it be economically viable? Probably not. Otherwise, we’d probably already be doing it.

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COVID, Quickly, Episode 9: Delta Variant, Global Vaccine Shortfalls, Beers for Shots



Today we bring you a new episode in our podcast series: COVID, Quickly. Every two weeks, Scientific American‘s senior health editors Tanya Lewis and Josh Fischman catch you up on the essential developments in the pandemic: from vaccines to new variants and everything in between.

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Coronavirus News Roundup: June 5 to June 18



The items below are highlights from the free newsletter, “Smart, useful, science stuff about COVID-19.” To receive newsletter issues daily in your inbox, sign up here.

Novavax reports that its two-dose protein-based vaccine against COVID-19 has been 100% effective in preventing severe illness, hospitalization and death due to COVID-19, as well as 90.4% effective against COVID-19 symptoms in large-scale human studies. These studies, which involved thousands of people in the U.S. and Mexico, showed that the vaccine also was highly effective against “Alpha,” the SARS-CoV-2 variant first identified in Great Britain, reports Carl Zimmer at The New York Times (6/14/21). “Novavax plans to apply for authorization in UK, EU, India, South Korea, and possibly the U.S.,” according to an Unbiased SciPod post (6/15/21).

A 6/17/21 story by Tanya Lewis at Scientific American describes some of the incentives being offered to people for getting vaccinated against COVID-19 — including lottery tickets, college scholarships, train tickets, firearms, cash pay-outs, cannabis joints, doughnuts, free trips, cruises, and gift certificates. “Public health experts use incentives all the time to get people to quit smoking, exercise more, and so on,” the story describes the director of the Health Decision Sciences Center at Massachusetts General Hospital’s general medicine division as saying. An unpublished study by the Mass General researcher suggests that incentives might effectively induce people to get a COVID-19 vaccine, Lewis reports. But for some people the best inducement is an opportunity to stop wearing a mask and a general return to normalcy, the story suggests.

Some positive news for people who have transplanted organs and thus take immune-suppressing drugs: a third dose of a mRNA vaccine against COVID-19 provoked a stronger immune response, at least in the form of antibodies, in organ transplant patients than the standard two doses did, per various reports. The findings, from a small study of patients who received a third dose this spring, were published 6/15/21 in Annals of Internal Medicine. The findings are “part of a broader discussion about whether and when to offer extra doses to vulnerable individuals,” writes Jennifer Couzin-Frankel at Science (6/14/21). In past studies, organ transplant patients who got a two-dose COVID-19 vaccine were far less likely to make protective antibodies against SARS-CoV-2 than the general population was. Some larger three-dose studies among people with compromised immune systems are under way, Couzin-Frankel reports. A medical oncologist at the University of Pennsylvania is not very worried about the effectiveness of COVID-19 vaccines among people with cancer, the story states. The story then describes two recent studies of cancer patients showing that they produced antibodies against SARS-CoV-2 after receiving a COVID-19 vaccine. However, a third study found much lower antibody levels among vaccinated cancer patients than it did among their healthy family members who also were vaccinated, Couzin-Frankel reports.

The Unbiased SciPod posted some helpful informational graphics about Pfizer’s ongoing studies of its COVID-19 vaccine in children under 12 (6/11/21). The post states that dosages have been set based on initial smaller studies in children (one-third the adult dose for ages 5-11 and one-tenth the adult dose for ages 6 months to 5 years), and that researchers will enroll 4,500 children across 90 sites globally for the larger safety and effectiveness studies. “Children have immune system components that are more potent compared to adults. They may not need as high a dose for protection. Age criteria are related to immune system development, not physical size,” the post states. The results will likely become available this fall for review by the U.S. Food and Drug Administration, with a first batch — from studies in children ages 5 to 11 — expected in early September, the post states.

Nearly one quarter of all people in the U.S. who were infected with SARS-CoV-2 last year, including 19% of those who never reported COVID-19 symptoms from their infection, had new medical problems within a month or more of recovering from the virus, according to a large study covered by Pam Belluck at The New York Times (6/15/21). Belluck writes: “Those affected were all ages, including children. Their most common new health problems were pain, including in nerves and muscles; breathing difficulties; high cholesterol; malaise and fatigue; and high blood pressure. Other issues included intestinal symptoms; migraines; skin problems; heart abnormalities; sleep disorders; and mental health conditions like anxiety and depression.” The study, conducted by non-profit organization FAIR Health and not formally reviewed by experts for flaws, involved evaluating electronic health-insurance records.

A 6/11/21 story by Emily Anthes at The New York Times runs down some evidence-based approaches that employers can take to reduce the risk of SARS-Cov-2 infections and other health problems as workers return to offices nationwide. Employers should flush unused taps and other plumbing to clear any metals or Legionella bacteria colonies that accumulated, the story states. Employers also should upgrade their ventilation and filtration systems, the story states. The goal is four to six air changes per hour, the story states, which is equivalent to completely refreshing air every 10 to 15 minutes in a room. Portable air purifiers or even “desktop level HEPA filters” can help. And continue to wash your hands routinely, for at least 20 seconds each time, advises a Northwestern University environmental microbiologist who is quoted in the story. Not solutions: desk shields (plexiglass barriers are a good idea in grocery stores though), foggers, fumigators, ionizers, ozone generators and other ‘air cleaning’ devices,’ the story states. In most non-medical or non-lab settings, wiping down surfaces with bleach solutions or disinfectant solutions or wipes does little to prevent SARS-CoV-2 transmission. Besides, inhaling these substances is harmful. “The no. 1 thing is to get vaccinated,” the story quotes Joseph Allen at the Harvard School of Public Health as saying.

A debate among scientists about whether SARS-CoV-2 spreads mainly by fallen respiratory droplets on surfaces that people touch or spreads in air hampered public health efforts to control the pandemic and to prevent deaths. The implications for this debate were crucial, as Megan Molteni at Wired writes (5/13/21) — officials need to know whether public-health messages should focus on hand washing or on masking and isolation or both, particularly before vaccines become available. The general debate is over, as you probably know — the virus is mostly spread in indoor air. But why did researchers disagree until recently? In part, it’s because the arguments against airborne SARS-CoV-2 all rested on an assumption that only particles smaller than 5 microns could hang in the air; larger ones, aka droplets, fall to surfaces. But in reality, larger particles can stay afloat and behave like aerosols, many scientists and engineers have known, including aerosols expert Linsey Marr of Virginia Tech, Molteni and others have written. Molteni’s story masterfully traces the events, conversations, and research that came to expose the “fallacy of the 5-micron boundary.” The hero of this engaging story is Katie Randall, a graduate student who specializes in detective work to figure out how bits of knowledge are passed along through published research papers over time.

Guidance from the U.S. Centers for Disease Control in April stated that international and domestic travel are low-risk activities for people vaccinated against COVID-19 (so, this does not pertain, unfortunately, to U.S. children under 12, for whom COVID-19 vaccines are not yet authorized). In response to that update, Ceylan Yeginsu at The New York Times has written up answers to some of the questions that vaccinated travelers have these days (6/15/21). A summary of the answers (again, this information is all for vaccinated people in the U.S.): 1) Yes, you must still wear a mask at the airport and on flights; 2) No, you don’t have to quarantine or test if you travel domestically, unless it is required by a state or territory; 3) No, you don’t have to take a coronavirus test before departure to international destinations — not for the U.S. at least; check for your destination; 4) Yes, you have to test, even if vaccinated, three days before you return by air to the U.S.; 5) Check lists of countries that will accept people from the U.S. under certain conditions, including some destinations in Europe and the Caribbean.

Scientists at the Walter Reed Army Institute of Research in Maryland are working on a vaccine that could protect us against all coronaviruses. In this 6/9/21 podcast at Scientific American, Emily Mullins interviews Dr. Kayvon Modjarrad who is leading the effort at Walter Reed to develop a so-called universal coronavirus vaccine. The vaccine candidate that is being tested “combines nanoparticles from a blood protein called ferritin with coronavirus proteins.” (Sorry, I’m not sure what that means either.) Modjarrad says 200 different combinations of spike proteins (a type of complex molecules that are found on the surface of all coronaviruses), types of ferritin, and ways to link them eventually yielded a vaccine candidate that repeatedly provoked a strong immune response against SARS-CoV-1, SARS-CoV-2 and three of its variants in several species of animals ranging from rodents to sharks. The vaccine now is being tested in a small group of humans. “If it works and is safe, it could provide a foundation for a universal coronavirus vaccine,” Mullin says.

You might enjoy, “A lexicon for the late pandemic,” by Jay Martel for The New Yorker (6/14/21).

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How End-of-Life Doulas Help Ease the Final Transition



Birth and death are the bookends of life, yet we welcome one and dread the other. Why is it that birth is celebrated, but death is taboo?

When a friend was expecting her first child, she needed additional support through her pregnancy, so she hired a birth doula. The idea of women helping other women during childbirth is not new. Since the beginning of time, women have labored and birthed at home, attended by a midwife and their female friends and kin. This camaraderie of women, once universal, was a way to provide birth support and also to pass on knowledge about pregnancy, childbirth and parenting.

The natural birth movement of the 1960s begged a return to this approach with women demanding unmedicated, less interventional births. Hence, the inception of the birth doula–a nonmedical caregiver who assisted pregnant women in the transition to motherhood.

Can the same idea apply to death? The evolution of death care has followed a similar trajectory to that of childbirth care. For most of human history, people were cared for and died at home, with corpses even displayed on the dining room table for mourning. This began to change in the mid-20th century as society saw great advancements in medical technology for diagnosis and treatment of illnesses. These developments moved health care away from the local doctor, who made house calls, to inpatient stays at hospitals. When people fell ill, they went to the hospital and eventually died there. In 1980, 60.5 percent of people died in hospitals. This number peaked in the mid-1980’s, but has since steadily decreased in response to a growing movement for death to be less medicalized, less institutionalized, and more natural. By 2016, half as many people (29.4 percent) were dying in hospitals, roughly equaling the number of people dying at home (30.5 percent). While this trend is encouraging, these numbers still do not reflect the fact that 71 percent of people would prefer to die at home.

I am a death doula, or what is now more commonly termed an end-of-life doula. This role grew out of the increasing awareness of and desire for more humane and compassionate ways to die. Similar to birth doulas, end-of-life doulas are nonmedical professionals offering emotional, spiritual, informational and physical support–not at birth, but at the other end of the spectrum of life–at death.

An elderly man with a terminal illness is afraid to die. He fears for the family he will leave behind–his wife, children and grandchildren–and how they will cope after he is gone. He has not expressed this fear to his doctors or to his wife, who is already handling so much. I listen. I hold space for his despair and angst. He realizes the fear is based on his immense love for his family. He drinks champagne with them on his deathbed. Reconciliation with the things that are important can allow one the peace to let go.

End-of-life doulas work with those with serious illnesses who are facing death–and also for those who are healthy and just want to prepare for death. On practical matters, doulas can advise on advance care directives, vigil planning and postdeath options, and assist with life review and legacy. On more emotional matters, doulas can facilitate conversations about unresolved issues or complex family dynamics and offer space for the fears and uncertainties around death and dying. When we are prepared for death, we are better able to face it when the time comes.

Despite her wish to die at home, an elderly woman is taken to the hospital by her son, who can no longer bear to watch his mother die in excruciating pain. The hospital wants to discharge her, finding nothing wrong, and, at her age, what can be done anyhow? The family is distressed by the hospital’s response and calls me. I suggest that they ask for a palliative care consultation. Eventually, the mother is placed on a proper pain management plan and discharged to hospice care. How do you know what to ask for, if you don’t know the choices?

Palliative and hospice care are philosophies of care that focus on comfort and symptom management to alleviate pain and suffering. Both are available to persons with serious illnesses. While palliative care can be given concurrently with curative care, hospice is typically for those who no longer seek curative treatments.

End-of-life doulas advocate for the wishes and needs of the dying person. We work with the health care team in ongoing care and coordinate with the support network of family and friends in place or help to establish a needed support system. We fill gaps in care and tackle tasks that are difficult to do or face. All the while, we can be a calming presence for loved ones and the dying person, especially for those who are facing death all alone.

A middle-aged man lies actively dying, completely nonresponsive, in his bed. He displays “death rattle” breathing, and his body has occasional violent spasms. At his bedside, a petite woman sits, his aunt, pained to watch her nephew die this way. After creating rapport with the aunt, I seek to allay her distress and encourage her to speak to him. The aunt responds gratefully, awakened to the possibility of making a difference for her nephew. He dies peacefully, immersed in soft light, music and love. Sometimes all a loved one needs is permission to be an active participant in the process, to turn helplessness into empowerment.

While death brings sadness and loss, there can also be positive emotions of love, honor and pride. It is possible to feel seemingly contradictory emotions all at the same time–because death is loss, and grief is the natural expression of love.

On the end-of-life journey, we doulas are your personal advocate, cheerleader, companion, guide, ear, rock–whatever you need us to be to face a difficult, intense and emotional time, because no one who wants support at the end of life should have to go without.

This is an opinion and analysis article.

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