Tuesday, February 11, 2020

Rat lungworm now in coqui frogs, bufos, even centipedes and crabs.

Coqui frog. Credit: U.S. Fish and Wildlife Service

This may read like something out of a Godzilla movie, but it has now become clear that rat lungworm disease has now teamed up with coqui frogs.

Researchers last year identified rat lungworm in the invasive, incredibly noisy frogs, and last month published a scientific paper on their findings.

Lungworm is spreading throughout the environment. Itʻs not only in rats, and of course humans and now coqui, but the scientists found it is also in centipedes, greenhouse frogs and even bufos.

The paper, "Occurrence of Rat Lungworm (Angiostrongylus cantonensis) in Invasive Coqui Frogs (Eleutherodactylus coqui) and Other Hosts in Hawaii, USA," was published in the Journal of Wildlife Diseases. The lead author is Chris N. Niebuhr of the USDAʻs National Wildlife Research Center Hawai`i Field Station in Hilo. Co-athors are Susan I. Jarvi, Lisa Kaluna, Bruce L. Torres Fischer, Ashley R. Deane, Israel L. Leinbach, and Shane R. Siers.

It still is not yet clear what role the new carriers play in transmitting the disease to humans, but it is clear that the rat lungworm is finding a pliant host in some of them: "In the frogs and toads, multiple tissue types were positive, including stomach and intestine, muscle, liver, heart, and brain, indicating larval migration," the authors wrote.

Rat lungworm is a nematode, a tiny worm that can cause severe neurological symptoms in humans. Here is the Hawai`i Department of Health website on the disease. 

Symptoms can go from nearly unnoticeable to severe pain and even paralysis.

Humans can be infected by, generally accidentally, eating it. Says the state Department of Health: 

"You can get angiostrongyliasis by eating food contaminated by the larval stage of A. cantonensis worms. In Hawaii, these larval worms can be found in raw or undercooked snails or slugs. Sometimes people can become infected by eating raw produce that contains a small infected snail or slug, or part of one. It is not known for certain whether the slime left by infected snails and slugs are able to cause infection. Angiostrongyliasis is not spread person-to-person."

The many source of human infection in the Islands seems to have been from unnoticed infected worms on salad greens, but as the nematode moves into new hosts, there could be new sources of infection.

The new hosts are referred to as paratenic or transport hosts. They are now believed to include frogs, toads, lizards, centipedes, crabs and other species. And while you might not directly eat these things, you or your pets could still be at risk.

The paperʻs authors wrote: " Although the species discussed here are not known to be intentionally consumed by humans in Hawaii, the ingestion of infected hosts could still pose a threat to other animals, because rat lungworm can infect both domestic and wild animals such as dogs (Canis lupus familiaris), horses (Equus caballus), and birds."

Rat lungworm in rats is excreted in their feces, which can be eaten by snails and slugs, as well as other species. Humans have been infected when eating uncooked greens with live slugs on them. 

With the disease now in frogs and toads and centipedes and the rest, new transmission could occur when uninfected rats eat infected specimens of those creatures. And with so many different carriers, it is possible new ways will emerge for humans to be impacted.

This is still an active area of research, the authors say, and more needs to be learned:

"Although our report of rat lungworm infections in frogs and centipedes implicates them as possible disease reservoirs, further investigations are warranted to better understand the role paratenic hosts may be playing in angiostrongyliasis transmission in Hawaii."

©Jan TenBruggencate 2020

Thursday, February 6, 2020

Climate change causing deep ocean churning

The oceans around Hawai`i are changing in many ways—and the latest to be detected is how fast the great currents flow.

Certainly the seas are warming, are acidifying, are rising, but now thereʻs evidence they are churning in ways that had not been predicted.

The evidence has been building. Five years ago, a paper in Science by Scripps researchers Dean Roemmich and John Gilson reported the great South Pacific Gyre had been increasing in speed, driven by increased surface winds. 

Those winds drive currents, and the currents have been speeding up for the past quarter-century, says a new report in Science Advances

"We have found a strong acceleration in the global mean ocean circulation over the past two decades. The acceleration is deep-reaching and particularly prominent in the global tropical oceans and can be attributed to the planetary intensification of surface winds since the 1990s," the authors wrote.

The currents not only are increasing in energy by 15 percent a decade, but they are also driving ocean mixing between shallow and deep waters.

"The increasing trend in kinetic energy is particularly prominent in the global tropical oceans, reaching depths of thousands of meters," say the authors, Chinese, American and Australian researchers Shijian Hu, Janet Sprintall, Cong Guan, Michael J. McPhaden, Fan Wang, Dunxin Hu and Wenju Cai. The paper is entitled "Deep-reaching acceleration of global mean ocean circulation over the past two decades."

What that means is complicated. It can mean that more atmospheric heating can be trapped and delivered into the deep oceans, reducing some of the immediate surface impacts of global warming, but also changing conditions for marine life in the deep oceans. It can change weather patterns on land and over the seas.

There is still a lot to know. Most of this paper is based on observations that go down 2000 meters (a little more than a mile), and it is still uncertain whatʻs happening in the very deep oceans.

"The data-void abyssal ocean is likely to be important. Thus, intensive observations that monitor the deep global ocean circulation are urgently needed not only for understanding past conditions but also for reducing uncertainty in future projections of the global ocean circulation," the authors say.

Wind speed is driving the increased water speed, and wind speeds are expected to continue to increase.

As little as 10 years ago, scientists were concerned that climate change was quieting the worldʻs winds, but even as they were writing those papers, the winds were picking up, dramatically.

©Jan TenBruggencate 2020

Sunday, December 22, 2019

Ugly fix preserves options for a classic steel library cart

I was presented recently with a 60-plus year-old library cart whose solid rubber wheels had flattened from sitting for years under load.

You could force it to roll, but it went "Ka-lunk Ka-lunk Ka-lunk," which is an annoying sound in a library. My job was to make it roll quietly.

It is a classic blue-painted steel cart with two bins and four wheels, two of which turn and two that donʻt. The rubber wheels still had the legible name of the manufacturer: The Colson Company of Elyria, Ohio.

Turns out Colson still exists, and their customer service is excellent. They had to refer me to one of their old-timers, who told me they closed their Elyria plant in 1957. So the cart is at least 62 years old, and maybe older.

Colson still makes wheels for library carts, but theyʻre modern designs. They no longer make the bulletproof steel wheels that were on this cart.

The cartʻs wheels still turn on their original greased bearings. Each wheel axle has its own Zerk grease fitting, and they still work. I greased them. The wheels can be taken apart to replace the solid circle of rubber that serves as a tire. I took one apart and removed the tire, to prove to myself that it was possible.

But as far as a couple of hours of internet searching was able to determine, the tires for this wheel are no longer made. Colson had no idea where to look.

Their Honolulu agent recommend I go ahead and replace the whole wheel mechanism with a modern plastic caster. But that seemed wrong. This American steel wheel was still functional, and someone long ago had designed and built it, understanding that it would last a long time. It could be serviced and was built so that the tires could someday be replaced.

After giving up on the internet, I went to local tire stores, local hardware stores, local car parts shops, all with no luck. I could not locate a replacement tire of the right size—three-inch center diameter, five-inch outer diameter, with the tire itself an inch thick in cross-section.

I even thought about using a giant O-ring to replace the tire, but the rubber would be too soft. Another option would be to find wheels the same size, and tear them apart to get the rubber wheels off and switch then to these wheels. Someone at a hardware store even suggested I could 3-D print a tire. Maybe thatʻs the eventual fix in the modern era.

Instead, for now, I used an abrasive grinder to grind the hard rubber wheels round again. It took a third of an inch off each wheel, but the old wheels are still turning, the cart is rolling quietly, and if anyone ever again makes a tire to fit them, theyʻll still be ready for a new set.

© Jan TenBruggencate 2019

Thursday, November 21, 2019

Everybody knows to avoid tuna when pregnant, right? Not so fast. Eating tuna might actually yield better results, says a large new study.

Eating ocean fish is good for you, but some fish have significant levels of methylmercury which is bad for you, so you should avoid those fish, right? Wrong, says a new study.

Mothers who ate seafood, even when it contained high levels of methyl mercury, had smarter kids than those who didnʻt eat seafood, says the comprehensive, peer-reviewed study.  

"Moderate and consistent evidence indicates that consumption of a wide range of amounts and types of commercially available seafood during pregnancy is associated with improved neurocognitive development of offspring as compared to eating no seafood," it said.

This flies in the face of conventional wisdom, and some medical wisdom. Both the U.S. Environmental Protection Agency and the U.S. Food and Drug Administration recommend against pregnant women eating ahi, over concerns about methyl mercury exposure.

There is no question that thereʻs methylmercury in yellowfin, bigeye and bluefin tuna, and that the amount has been increasing in recent years. There are also significant amounts of mercury in blue marlin and other species. 

The Hawai`i Department of Health warns against pregnant women eating any blue marlin, swordfish and shark and recommends severe limits on consumption of tunas. 

Yet the new study suggests women who eat some ocean fish, even when mercury levels are high, actually have kids who have better mental outcomes. The authors wrote: " No net adverse neurocognitive outcomes were reported among offspring at the highest ranges of seafood intakes despite associated increases in mercury exposures."

The paper is entitled, "Relationships between seafood consumption during pregnancy and childhood and neurocognitive development: Two systematic reviews." It is published in the journal, Prostaglandins, Leukotrienes and Essential Fatty Acids. Its authors come from some of the most prestigious medical and scholarly institutions in three countries, including the Center for Food Safety and Applied Nutrition, American Society for Nutrition, National Institutes of Health and others.

So whatʻs going on? The authors say thereʻs something in seafood that counteracts the impacts of mercury, and makes it even healthier for kids to eat seafood than not to eat it.

Here is the technical way they say that: "This evaluation of seafood consumption inherently integrates any adverse effects from neurotoxicants, and benefits to neurocognition from omega-3 fats, as well as other nutrients critical to optimal neurological development."

Even small amounts of seafood have a beneficial effect, and the study found no downside to large amounts: 

"Benefits to neurocognitive development began at the lowest amounts of seafood consumed in pregnancy (4 oz/wk) and up to >100 oz/wk, with benefits to age appropriate measures of neurocognitive development including an average increase of 7.7 IQ points, in evaluating 44 publications reporting on 102, 944 mother-offspring pairs, no adverse effects on neurocognitive development were found."

It is not that the mothers and children arenʻt exposed to methyl mercury. They are, but there appear to be no negative impacts from that exposure from seafood, the paper says: "No net adverse neurocognitive outcomes were reported in offspring at the highest ranges of seafood intakes despite associated increases in mercury exposures."

The authors are aware that this is controversial stuff, and they urge the scientific community to do more research. There needs to be work, they say, that follows the children into older age, research into whether fatty or oily fish like tuna are healthier than white-fleshed fish, on making sure the IQ tests in studies are comparable, and research on differences based on species of fish and of how it is prepared.

But how is it possible that mercury exposure in kids is dangerous, except when it comes from fish? 

The authors of this paper donʻt say in the publication, but others have suggested that seafood contains something else that protects against mercury- namely, selenium.

This study from 2010 argues that selenium protects against mercury poisoning, and it cites studies indicating selenium can actually reverse some of the effects of methylmercury toxicity. 

"Studies of populations exposed to MeHg (methyl mercury) by eating Se-(selenium) rich ocean fish observe improved child IQs instead of harm."

Tuna and most billfish tend to have high levels of selenium, which may help explain things. Hereʻs a useful report from NOAA and other agencies.

© Jan TenBruggencate 2019

Monday, November 18, 2019

Kauai koloa: the native ducks on the Garden Island are still pure

The native Hawaiian duck, koloa, still rules on Kaua`i—retaining nearly all its native genetic heritage.

You can see pairs and even families of ducks lift off the newly cleared sections of Niumaluʻs Alakoko Fishpond on Kaua`i, and from the ancient taro lo`i in Hanalei. You can see them swim in streams around the island of Kaua`i, and waddle along the banks of the ponds at Kaua`i Lagoons at Nawiliwili.

A new genetic study, published today in the journal Molecular Ecology, says most ducks on Kaua`i are pure koloa, although many on other islands have interbred with mallards.
Kaua`i koloa. Credit: FWS image.

The paper is entitled "Persistence of an endangered native duck, feral mallards, and multiple hybrid swarms across the main Hawaiian Islands." The lead author is Caitlin P. Wells, of the University of California at Davis. 

Co-authors are Philip Lavretsky, Michael D. Sorenson, Jeffrey L. Peters, Jeffrey M. DaCosta, Stephen Turnbull, Kimberly J. Uyehara, Christopher P. Malachowski, Bruce D. Dugger, John M. Eadie and Andrew Engilis Jr.

Koloa were once present on all the islands, but due to predation, hunting and other causes, they were gone by the 1960s from all islands except Kaua`i and Ni`ihau. Captive breeding and release have returned some koloa to other islands since, but the populations remain low.

The researchers, in attempting to get a sense of how significant was the hydbridization with non-Hawaiian birds, collected blood samples from 425 ducks across the Hawaiian Islands.

Their finding was that Kaua`i birds are still close to pure koloa, while those on the other islands are blends—hybrids between koloa and mallards.

"We found that despite a population decline in the last century, koloa genetic diversity is high. There were few hybrids on the island of Kauaʻi, home to the largest population of koloa.

"By contrast, we report that sampled populations outside of Kauaʻi can now be characterized as hybrid swarms, in that all individuals sampled were of mixed koloa × mallard ancestry," the paper reported.
Many species that have dropped to really low numbers suffer from a decline in genetic diversity, meaning they have a reduced capacity to evolve in response to changing conditions. 

In a press release about the study, lead author Wells said that the genetic diversity in the Kaua`i birds suggests they can respond well to changes in the environment. 

"Should the environment change, due to things like climate change, there's a lot of potential for the koloa to evolve on its own, given the genetic diversity we've seen," she said.

"The fact that the koloa on Kauai are pure and have a lot of genetic variation are two really positive things that came out of this study," Wells said.

The two-decade study involved researchers from the University of California at Davis, Fish and Wildlife Service, University of Texas at El Paso, Wright State University, Oregon State University and the Hawai`i state Division of Forestry and Wildlife. 

 © Jan TenBruggencate 2019