University of Hawai`i astronomers detect asteroid collision beyond Mars.

There’s a lot of empty space in space, but there’s a fair amount of stuff zipping around in it.

Collisions are rare, but inevitably, they happen—it accounts for craters on the Moon, and some of the features on the Earth.

(Image: Main-belt asteroid (493) Griseldis with temporary tail. Credit: David Tholen, Scott Sheppard of Carnegie Institution, Chad Trujillo of Gemini Observatory.)

And recently, a University of Hawai`i telescope helped spot one out farther from the sun in our own solar system.

Out in the Asteroid Belt, between Mars and Jupiter, on March 17, astronomers using the 8-meter Subaru Telescope on Mauna Kea noticed that an asteroid named Griseldis had suddenly grown a tail.

Several days later, the 6.5-meter Magellan telescope in Chile showed the tail was still there, but smaller.

Images taken by the University of Hawai`i’s 2.2-meter telescope on Mauna Kea showed that the tail did not exist back in 2010 or 2012, and that it had disappeared by March 24. Magellan on April 18 and May 21 also showed the tail was gone.

University of Hawai`i astronomer David Tholen reported the results at a Nov. 12 session of the Division for Planetary Sciences of the American Astronomical Society.

The sudden appearance and quick disappearance of a tail suggests something crashed into the asteroid, caused a plume of dust, which then dissipated, Tholen said.

“The observations are consistent with the occurrence of an impact event on this asteroid,” the research group working on the project said.

The University of Hawai`i press release on the event
is here. 

© Jan TenBruggencate 2015

Dengue: You don't know how big a threat it is. It's big.

Not too worried about dengue fever? 

You should be. It is the leading cause of illness and death in the tropics and subtropics. It's a miserable disease to have. 

The U.S. Centers for Disease Control and Prevention (CDC) say 400 million people annually are infected.

And there’s a lot you likely didn’t know about this mosquito-borne disease, which has showed up and been defeated several times in the Hawaiian Isands, but now appears widespread now on the Big Island. 

One feature of the disease is that there are four different related viruses that cause dengue. If you get one, you’re protected from getting that one again, but after a few months you can get any of the other three. Most parts of the world have all four types.

There is some evidence that if you get a second type after a first infection, the symptoms can be significantly more severe.

Dengue is pretty much everywhere within a thousand miles or so of the equator—Hawai`i has been one of the outliers in not having it.

There is no vaccine for it so far, although there's a lot of work being done toward a vaccine. Your best hope of not getting it is not getting bitten. 

It is possible to have the infection and not have symptoms—but you’ll still be able to pass the disease to others via mosquito bites.

Dengue is in a group of viruses called Flaviviruses. Yellow fever and West Nile are also in that group. It causes illness that outwardy mimics a lot of other disease, even flu. It can be very similar in outward appearance to another tropical disease called chikungunya. Says the CDC: “Chikungunya and dengue are both acute febrile illnesses characterized by fever, myalgia, and lethargy. Some patients may also have … rash, nausea, vomiting, and headache.” 

Fortunately, we don’t have chikungunya in the Islands. On the other hand, dengue is worse: “Chikungunya is rarely fatal. In contrast, early identification and proper clinical management for hospitalized dengue cases can reduce the case-fatality rate from 10% to less than 0.1%. Therefore, patients suspected of having dengue or chikungunya should be managed as having dengue until dengue can be ruled out.”

Dengue can be transmitted blood to blood, but the main reservoir for infection is mosquitoes. Two mosquito varieties can carry dengue, Aedes aegypti and Aedes albopictus. We have both of them in Hawai`i. Albopictus, the Asian tiger mosquito, is a daytime biter. Aegypti is a daytime biter that’s most active a couple of hours after dawn and before sunset. Aegypti is the one you’re more likely to find inside your house.

The virus is creepily robust. Most get it from the mosquitoes, but folks working in laboratories have been infected: “The virus is stable in dried blood for up to 9 weeks at room temperature,” says the Public Health Agency of Canada. Dengue isn’t in Canada, but visitors to the tropics can bring it home.

You get sick 4 days to a week after being bitten, and you can stay sick 3 to 10 days. In some people, it can progress to more serious diseases called dengue hemorrhagic fever and dengue shock syndrome, which can be fatal. These diseases are more common in young children than adults.

Folks who have traveled in the tropics often have experienced airline crews spraying insecticide up and down the aisles. Often, that’s for dengue, which can be so painful it’s called “breakbone fever.”

You avoid getting dengue by avoiding getting stung by infected mosquitoes. Recommendations are to stay out of areas with lots of mosquitoes, and to wear protective clothing and insect repellent if you must be there. Also, reduce mosquito numbers in your environment by emptying standing water where they breed in pots, plants, and other locations. 

Longer term, to stop the cycle of infection, public health authorities need to break the cycle of humans passing the disease to mosquitoes and mosquitoes passing it to humans.  If new infections can be stopped for several weeks, the cohort of infected mosquitoes can die off, and the reservoir of infectivity is shut down. A mosquito, once it picks up the virus, can pass it on for its lifetime, but does not pass it on to its young.

Once again, the key symptoms of dengue, according to CDC, are a lot of pain—headache, pain behind the eyes, joint pain, muscle pain, bone pain—and also rash, mild bleeding from the nose or gums, and bruising or red and purple spots on the skin. Lab tests will show low white blood cell counts.

Victims should seek immediate medical attention, CDC says, if the symptoms move to severe abdominal pain or persistent vomiting; red spots or patches on the skin; bleeding from nose or gums; vomiting blood; black, tarry stools; drowsiness or irritability; pale, cold, or clammy skin; or difficulty breathing.

Resources:

The Hawaii State Department of Health fact sheet on dengue. 

The Centers for Disease Control and Prevention web pages. 

World Health Organization treatment guidelines. 

© Jan TenBruggencate 2015

Natural pesticides from a common weed launched Kaua`i's pesticide furor

(Note: A version of this article appeared Nov. 17, 2015, in Honolulu Civil Beat.) 

The plant blamed for much of Kaua`i’s pesticide furor is a medicinal, edible shrub with a truly awful smell. 

It flowered again recently, sending across the West Kauai landscape a rank stench which, in susceptible folks, can cause teary eyes, headaches and nausea.

West Kauai sugar plantation workers call it spiderflower, but it is more often known as stinkweed; its scientific name is Cleome gynandra.

In November 2006, students and staff at Waimea Canyon Middle School complained of a bad smell that made them nauseous and left them with throat irritation, watery eyes and dizziness. Many attributed it to agricultural spraying on a field next to the school. 

It flowered again recently—the same time of the year as the initial 2006 report—and on West Kauai, people were once again complaining about the stench.

(Image: A ratty-looking sample of stinkweed, Cleome gynandra, in a field west of Kekaha on Kaua`i. Credit: Jan TenBruggencate. )

When I heard of the latest stinkweed outbreak in the second week of November 2015, I went to West Kauai and collected samples (in sealed plastic bags) in Waimea, Kekaha and Mana—some on my own and some during a driving tour with Allan Smith and Robin Robinson of Syngenta, a seed company that leases extensive acreage in the area.

(Image: A healthier looking stinkweed photo specimen.  Credit: Forest and Kim Starr.)

One of the things that struck me about the plant is that its smell is so variable. Some specimens smelled not at all. Others were very strong—enough to make you gag. Some had a very intense chemical smell, others a smell similar to the popular local vegetable bittermelon (Momordica charantia). When it was blooming in past years, Robinson said, sugar plantations would sometimes get calls about a petroleum odor, with callers suggesting there must be a fuel spill nearby. 

“I can smell the sulfur in it,” said one person I asked to smell the plant sample in one plastic bag. “But this sample over here smells almost good.”

This variability is confirmed on the website for Plant Resources of Tropical Africa, which says people who grow it commercially have difficulty getting consistent results, because of variability in many features of the plant. 

The variability also helps explain why some of the affected individuals at Waimea Canyon Middle School, who said they were familiar with stinkweed elsewhere, insisted that it’s not what they smelled at Waimea.

The Hawai`i Center for Food Safety, in its Pesticides in Paradise report, insists that pesticides and not any plant are to blame: "A teacher...rejected the explanation given by Hawai`i officials and Syngenta that 'stinkweed' was he culprit, saying she was familiar with stinkweed's odor and that was not the cause."

The flowering alone can release a strong odor, but if the plant is rubbed or crushed, or if a field of stinkweed is plowed, the stink can be overpowering. One of the reported incidents at Waimea Canyon Middle School occurred while the plant was flowering, another while the stinkweed-infested field was being tilled, Robinson said.

Waimea Canyon Middle School was impacted several times from 2006 to 2008 with the odor that apparently blew in from a neighboring field. Many of the teachers and parents of impacted students blamed agricultural spraying on nearby fields. 

The much-criticized CFS report argues that "Communities in Hawai`i are rightly concerned about pesticide drift that occur from open-air GE seed corn operations. Teachers and schoolchildren in Waimea on Kaua`i became sick on at least three separate occasions following chemical applications to a nerby seed corn plot...

"In a 2008 episode, 60 children and at least two teachers experienced headaches, dizziness, nausea and/or vomiting; 10 or more children were treated at an emergency room, several were put on a nebulizer to relieve respiratory distress and one as given an anti-vomiting medication intravenously."

The state commissioned a study by Qing X. Li, Jun Wang and Robert Boesch, of the University of Hawai`i’s Department of Molecular Biosciences and Bioengineering. Their findings, which are rejected by some of the affected school folks, concluded that spiderflower/stinkweed is a powerful chemical factory.

“A closed chamber laboratory air emission study identified 29 chemicals (some with insecticidal activities) produced by stinkweed,” they said in their report. When they compared that with air samples in the field, they found all 29 chemicals in the air. When they tested the air at the school—indoors and outdoors—they found about half of those chemicals.

The chemical that the scientists felt was likely most at fault is a natural, plant-based compound called methyl isothiocyanate (MITC), an organosulfur compound. Their studies showed it is significantly higher in concentration in flowers and seed pods than leaves and stems of the stinkweed.

“MITC is a highly foul-smelling, noxious chemical at high concentrations, and is cited as a potent lachrymator (eye irritant) and nose and throat irritant. Besides MITC, other stinkweed derived compounds found during this study are also known potential irritants,” they wrote.

The studies also found residues of five known pesticides. When they did the air quality testing, they found that “Concentrations of the pesticides and MITC were well below health concern exposure limits or applicable screening levels.”

The plant has been in the Hawaiian Islands for more than 150 years, having first been observed in 1857. It is on all the main islands, sometimes known as honohina, `ili`ohu, wild spiderflower or spiderwisp. It is native to central America, from Texas south to Argentina, according to the Manual of the Flowering Plants of Hawai`i.

It has spread around the world, a weed in some areas and a cultivated plant in others. The leaves are eaten in Africa and parts of Asia, although it must be cooked. One Thailand website warns that cooking, drying or fermentation reduces the levels of hydrocyanic acid, which it says is toxic to central nervous system. 

The plant is attractive to some insects; repellent to others. In some areas it is used as a mosquito and tick repellent, but when I viewed it on West Kaua`i, many species were severely infested with

It seems to do best after a rain in the drier parts of the Islands. It is recognized by a 5-part leaf (sometimes 3 or 7), long narrow seed pod, and small white flowers that have long spidery parts extending beyond the petals.

It is in the Capparaceae family. A native Hawaiian plant in the same family is maiapilo or pua pilo.

© Jan TenBruggencate 2015

Wet years now dry: the transition to an ever more arid Hawai`i

While El Nino events often mean winter drought in the Islands, it has long been understood that the counterpart, La Nina, brought increased rainfall.

But that balance, which helped restore depleted groundwater reservoirs, appears to have been broken, according to Hawai`i and China researchers.

La Nina—the cold cycle that often occurs between El Nino warm cycles—now no longer brings additional rain, according to a paper in the Journal of Climate. 

The paper is entitled. “Variability of Hawaiian Winter Rainfall during La Niña Events since 1956.” Its authors are Christopher F. O’Connor and Pao-Shin Chu, of the University of Hawai`i Department of Atmospheric Sciences, School of Ocean and Earth Science and Technology, Pang-Chi Hsu, of China’s Nanjing University, and Kevin Kodama, of the Honolulu National Weather Service.

“Rainfall in Hawaii during La Niña years has undergone abnormal variability since the early 1980s. Traditionally, Hawaii receives greater-than-normal precipitation during the La Niña wet seasons. Recently, La Niña years have experienced less-than-normal rainfall,” they write.

The reason seems to be that La Nina itself is changing, they said.

"Variations in tropical sea surface temperatures and circulation features in the northern Pacific Ocean have changed during La Niña wet seasons, thus changing La Niña–year rainfall.”

A lot of our moisture in winter comes in the form of storm systems that blow through. They’re not blowing through as consistently, the authors write.

“A storm-track analysis reveals that the changes … are creating a less favorable environment for the development of Kona lows and midlatitude fronts in the vicinity of Hawaii.”

The fact that the Islands are drier than they used to be is not news. This latest El Nino work helps explain the mechanics of why rainfall is dropping. 

The National Climate Assessment of 2014 reviewed some of the bad news. 

“Freshwater supplies are already constrained and will become more limited on many islands,” that report said. “On most islands, increased temperatures coupled with decreased rainfall and increased drought will reduce the amount of freshwater available for drinking and crop irrigation.”

RaisingIslands has been covering this dryness trend for years. 

Here is a report on weakening tradewinds and their impact on rainfall. 

Here is a report reviewing reduced rainfall on Haleakala over the past quarter-century. 

Here is a report on the increasing frequency of El Nino andLa Nina events.

© Jan TenBruggencate 2015