Link suite overview: On vector-borne disease and climate change, connecting the infinitesimal and the invisible, Dopey Does DDT, the need for ecosystems thinking & bugs gone borg
It is a midsummer night’s feast and we are on the menu. Nibbled and sipped by winged vampires and blood-sucking squatters, we scratch, swat and fret. But the bugs, annoying though they may be, are merely messengers. Virus, bacteria, rickettsia, protozoans and helminths—those are the ones turning the whole predator / prey equation on its head.
From a safe distance, preferably behind screens, pants tucked sensibly into socks and doused in parfum-de-DEET, the elegance of the big picture is both undeniable and astonishing. This is the web of life at its webbiest, connecting the fates of the infinitesimal to the invisible—shifts in weather patterns, changes in climate—and everything in between.
A bird flies a little further north than usual one spring, staking out territory in what, for it, is literally new territory. A warmer, more humid world has brought earlier thaws and later freezes to this particular neck of the woods. Which is also good news for the bird’s passengers: the ticks on its body, mites on its wings, virus and bacteria in its blood. Occasionally even something as big as a snail manages to survive the journey, berthed in a bird’s gut, likely carrying a parasitic payload of its own.
For everything we can see changing in the landscape—tundra to forest, swamp to sea, lake to desert—there is so much more going on at the edges of detection.
A deer tick finds itself in grasslands favored by voles rather than the forest, where white-footed mice rule the leaf litter. But a blood meal is a blood meal. So the tick latches on and borrelia—the bacteria carried by the tick that causes Lyme Disease—sets up shop in a new animal host. This is the Disease Cycle as jazz, constantly riffing theme and variation. Innovation as making do.
While global trade and travel do a mighty job of mixing up the pot, speeding the spread of pathogens and invasive species, climate change alters the basic recipe. How do you restore a tundra whose permafrost has melted? Or a rainforest weakened by repeated periods of drought? How do you make plans for a world in transition to a “new normal”?
Pollution, carbon emissions, deforestation—all at least hold out the possibility of reversal: things can be done, if only we would do them.
Climate change is a dragon awakened.
“Bite!,” the new link suite-story on the TrackerNews aggregator, surveys a variety of vector-borne diseases, all on the rise due, at least in part, to climate change: Cold-blooded insects prefer a warmer, wetter world.
It is not their only stroke of luck. Tight budgets in the US have put mosquito abatement districts in the political cross-hairs as an easy target for “saving” taxpayers money, no matter the expense of taxpayer illness. Lose the public abatement districts and there would be no coordinated surveillance for West Nile virus. Or for dengue, which has recently established a foothold in Florida decades after it was eradicated. Or for the next headline horror—chikungunya?—on the horizon. The standard bureaucratic spin about”the best science available” falls flat when the “best” is barely any at all.
Bugs—and the bugs they carry—won’t disappear even if the data do.
Funding actually needs to go up. Way up, according to Peter Hotez, president of the American Society of Tropical Medicine and Hygiene, dengue is “a bigger threat than many of the biodefense pathogens that we’re spending huge amounts of money on. Dengue and other vector-borne diseases are a true homeland security threat.”
Really, though, they are a global security threat and public health disaster. For every breakthrough…
…there are setbacks. Babesia, a parasite carried by ticks—including the tick that transmits Lyme Disease—causing a malaria-like illness, is on the ascent. Diagnosis and treatment an be tricky. There is no vaccine. Further complicating matters, a single tick can deliver both babesia and borrelia.
Humans are hardly the only animal hosts under assault:
- Cow babesia is among the most serious cattle plagues worldwide. Ticks are becoming increasingly resistant to the chemical brews used to keep it at bay. In the US, a team of “tick riders”—cowboys on horseback—patrol the Mexican border, checking cattle and deer along the Mexican border. It is estimated that if tick fever were to take hold again in the US (it, too ,was eradicated decades ago), the damage could easily exceed $1 billion in just the first year.
- Lice are killing up to 90% of young wild salmon swimming past farmed fish pens on their way to sea. Sea lice were wildlife plague that amplified in domestic stocks. The concentrations are so high, the small fish are literally bled to death.
- Moose are facing a similar fate from “winter ticks.” These are ticks that latch onto to moose in the fall, burrow into their coats and feed all winter. It used to be a moose might pick up 30,000 ticks, a horrifying but survivable number. But a shifting climate means snow melts earlier. Ticks fall off onto dry ground in the spring, allowing more to survive. Their breeding season is longer, too. Now “ghost moose” have been found with over 100,000 ticks. Like the baby fish, they are being bled to death.
DOPEY DOES DDT
Meanwhile, cases of leishmaniasis, a parasitic disease carried by sand flies, are also on the rise, bedeviling everyone from soldiers in Afghanistan to the beleaguered residents of the world’s newest country, South Sudan. Efforts in India to eradicate the disease by 2010 failed spectacularly.
Yet simply getting rid of sand flies could lead to other problems: As larvae, they eat garbage.
Single-focus wars-on-fill-in-the-blank-disease rarely work (only smallpox and the cattle scourge rinderpest have been effectively wiped out, and notably neither were vector-borne).
In the early 1940s, the Walt Disney Company produced a series of short educational films, among them, “Winged Scourge,” in which the Seven Dwarfs (yes, those seven dwarfs) take on Public Enemy Number 1: the Mosquito—”wanted dead or alive”… (HT to epidemiologist and author of the marvelous Aetiology blog Tara C. Smith)
Wrapped in gobsmacking kitsch is a matter-0f-fact portrayal of then state-of-the-art pest control: drain wetlands, coat breeding ponds with oil and waterways with Paris Green, spray copious amounts of insecticide (likely DDT, given the time frame), put up screens, seal building cracks and use bed nets. It worked, too, at least for a while, if you don’t count the cascade of eco-disasters that followed.
Not only is there a need for an “ecosystems thinking” approach, but one that can accommodate fast-changing landscapes. What was, isn’t any more. What is, won’t be for long.
The climate dragon is awake, scattering clouds of mosquitoes, flies, fleas, mites, ticks and lice as it yawns, stretches and shakes off a millenia-long slumber.
- Wicked Bugs: The Louse that Conquered Napoleon’s Army and other Diabolical Insects by Amy Stewart / book website
- Under Our Skin, documentary by Andy Abrahams Wilson chronic Lyme Disease / website
- Mites, background & micrographs / Systematic Entomology Lab, USDA / website
- Hybrid Insect Micro Electromechanical Systems (HI-MEMS) / DARPA / website
- Loss of Top Predators Has Far-Reaching Effects / PBS Newshour
- Earth, Land and Ethics: The (still unlearned…) Lessons of Aldo Leopold / TrackerNews “Dot to Dot”
Filed under: climate change, disease surveillance, epidemiology, food, TrackerNews, vaccines | Tagged: Amy Stewart, babesia, borrelia, climate change, Disney, ecosytems thinking, fleas, global warming, Hybrid Insect Micro Electromechanical Systems (HI-MEMS), leisthmaniasis, Lyme Disease, malaria, mites, moose, mosquito abatement, mosquitoes, parasites, salmon lice, sand flies, Tara Smith, ticks, typhus, vector-borne disease, Wicked Insects, Winged Scourge, winter ticks | Leave a comment »