Viruses and sandcastles at the beach

It's Saturday and it's summertime and Mrs. R. and I are still in the city. OK with me. I'm a city boy and find it easiest to maintain upright posture on asphalt, but my bride of 37 years likes the beach, so most summers we go off for a few weeks to the seashore (speaking littorally). It's down south where the water is warm but I still spend a lot of time inside in air conditioned splendor, listening to music and reading. Mrs. R. props herself up at the earth - water interface with her own pile of books, far from other people and the hazards of pathogenic viruses. It turns out, not really.

Perhaps because of a perverse pleasure I take in the hazards of nature, my eye was attracted to two pieces about viruses at the beach. The first was just a notice in Nature Protocols (hat tip ti tweet by @andrewcsinger):

Viruses are the most abundant and dynamic biological entities in the world's ecosystems. Marine sediments, the largest biome in the world, have the potential to represent an optimal environment for viral development. To assess the viral effect on their hosts, and to understand the ecological role of the viruses in the benthic food webs and biogeochemical cycles, measurements of benthic viral production are needed. Different direct and indirect approaches have been proposed to estimate viral production in aquatic sediments, but a standardized protocol is not available yet. The method presented in this protocol relies on the short-time incubations of sediment samples with virus-free seawater, and the subsequent determination of the increase in viral abundance over time by epifluorescence microscopy. The protocol described here is highly reliable, inexpensive and easy to use. The entire procedure takes approximately 3 days to be completed, but the method allows the parallel processing of several sediment samples, which is recommended in ecological studies. (Dell'Anno et al., Nature Protocols)

So we know very little about viral abundance in sea water and sediment and this made me wonder about unrecognized reservoirs for viral pathogens in the environment. The natural home for influenza virus is birds, but they can infect other animals, too. We haven't looked in many places. A virus needs a living host cell to replicate. It's an obligate intracellular parasite. It isn't "alive" in the same way a bacterium or yeast or fish is alive, so if it's hanging around at the beach it needs a host cell. But there are tons of organisms in the sea and ocean sediment. Do we know flu can't be sitting around in some of those cells?

OK. That's rank speculation. I have absolutely no evidence there's flu replicating at the beach. But there is evidence there are pathogens there. A new paper just published in the American Journal of Epidemiology makes a surprising association between building sandcastles and gastrointestinal and respiratory illness:

Children and adults who build castles and dig in the sand at the beach are at greater risk of developing gastrointestinal diseases and diarrhea than people who only walk on the shore or swim in the surf, according to researchers from the University of North Carolina at Chapel Hill and the Environmental Protection Agency.

People who playfully bury their bodies in the sand are at even greater risk, according to the study published online recently in the American Journal of Epidemiology. It also shows children, who are more likely than adults to play with and possibly get sand in their mouths, stand the greatest chance of becoming ill after a day at the beach.


The study is based on interviews with more than 27,000 people who visited seven freshwater and marine beaches in the agency’s National Epidemiological and Environmental Assessment of Recreational Water Study (NEEAR) between 2003 and 2005 as well as in 2007. All beaches in the study had sewage treatment plant discharges within seven miles, although the source of sand pollution was unknown and could have included urban runoff as well as wild and domestic animal contamination. Water quality at the beaches was within acceptable limits, [Chris Heaney, Ph.D., a postdoctoral epidemiology student at the University of North Carolina] said.


People were asked about their contact with sand on the day they visited the beach (digging in the sand or whether they were buried in it). Then, 10 to 12 days later, participants were telephoned and asked questions about any health symptoms they had experienced since the visit. (U. North Carolina Press Release)

An association between contaminated water and illness has already been demonstrated, but this the first time that beach sand has been implicated. What kind of illnesses showed up? GI crud like diarrhea, upper respiratory illnesses, rash, eye ailments, earache and infected cuts. The risk wasn't dramatic: about 10% to 20% more common in the diggers and buriers and the rate of post beach illness isn't all that great either: maybe 10%. So we're talking about maybe one or two extra cases in 100 people from playing in sand.

But the risk of staying inside and reading science is zero.


More like this

As I write this I am at 30,000 feet winging my way to Montreal, Canada, where the temperature is below freezing. So what more appropriate topic than microbial hazards of bathing beaches? Maybe it was my foray into the wonderful world of fecal accidents that prompted me to look further into the…
We've been traveling again (and offline), so we'll limit this to a few comments to put recent news into the context of things we talked about here recently (an excellent up-to-date status report can be found by DemFromCT at DailyKos). A good article by Rob Stein of the Washington Post highlighted…
A reader (hat tip River) sent me a link to a New York Times piece quoting a physician who recently saw swine flu cases in Mexico City. He called attention to what seemed like an anomalous clinical presentation of many cases. Besides a higher proportion of gastrointestinal symptoms (nausea, vomiting…
As I mentioned yesterday, the epidemiology of hemolytic uremic syndrome (HUS) was murky for several decades after it was first defined in the literature in 1955. In the ensuing decades, HUS was associated with a number of infectious agents, leading to the general belief that it was a "…

> But the risk of staying inside and reading science is zero.

I think you mean "from" not "of". I agree the risk of staying inside is probably zero, but the risk from reading science is clearly non-zero. For a start, it might give you ideas, and these are increasingly dangerous in this enlightened world

By Just An Australian (not verified) on 11 Jul 2009 #permalink

Did they exclude the possibility that certain organisms increase the probability that people will engage in these behaviors?

Makes me wonder what the viral risk is for kids playing in a sandbox at a playground in a heavily populated urban area...

Think I'll keep to the woods!

If there's a sandbox in the world that hasn't been discovered by the local cat population, that's the one I'd want my kid playing in.

But what I really want to know is this: how valid is my assumption that the local (outdoor) swimming pool is relatively safe as far as swine influenza (by whatever name) is concerned? I'm hoping that the intense UV should take care of any virus that didn't succumb to the chlorine in the water, but I guess I'm also hoping that maybe the sun exposure renders the regulars somewhat less susceptible to begin with. I'd hate to give it up, but I'm generally inclined to err on the side of caution where flu is concerned, and flu activity is being reported at the widespread level here in California.

I dunno. The risk of staying inside and reading science might be in wasting a beautiful summer day because you're afraid of a bellyache.

If you like to stay inside and read science, then that's one thing. But letting fear keep you away from living your life in a way you love -- going to the beach, for instance -- then that's far more serious than any virus you could pick up at the shore.


You can always follow Mrs. R's lead and read at the beach (or by the pool; for me, "swimming" consists mainly of reading, punctuated by the occasional dip in the water). One of my favorites is "A Scientist at the Seashore", by James S. Trefil -- there's a lot more to bubbles and sand and waves than is obvious to the casual observer. Trefil's book could have been titled "A Physicist at the Seashore", probably a more pleasant (if no more fascinating) read than Dell'Anno's "A Microbiologist at the Seashore".

Curious: I assure you staying inside isn't related to my fear of contagious disease. I regularly eat all sorts of stuff from street food vendors. It's because I'd rather read science in comfort and with distractions of my own choosing (my choice of music).

Racter: Mrs. R.'s big joke is that in Hawaii when she was at the beach I was inside the hotel room 40 floors up reading "Scientist at the Seashore." As for pools and flu, we don't know. You can make good arguments either way (and you made some good ones why it isn't a problem). I'd just followyour inclinations on this one and notworry about flu. No data.

> But the risk of staying inside and reading science is zero.

He He, I like that one ;-)

>>The risk of staying inside and reading science might be in >>wasting a beautiful summer day because you're afraid of a >>bellyache.

But not if "reading science" is one's most interesting and thrilling pastime anyway ;-)

By h1n1_watcher (not verified) on 11 Jul 2009 #permalink

Oh Revere, I wasn't talking about you personally! :) I was talking about the rest of us, who might read this and decide to stay home from our trip to the beach.

I'm personally glad you love to read science, because I learn a lot stopping by here. Enjoy your vacation!

How do you know the book you are reading doesn't have some nasty bug on it's pages?

By Who Cares (not verified) on 11 Jul 2009 #permalink

ow do you know the book you are reading doesn't have some nasty bug on it's pages?

Good question. I think I'll autoclave them this summer.

not to mention the vibrio genus of bacteria, whose natural home is generally seawater, and which contains the bacterium vibrio cholerae, perfectly capable of causing an epidemic itself.

Self conscious that I am unlikely to add technical revelations to EM's incredible knowledge base/exchanges. Think of me perhaps as a sort of Jane Q Public, very happy to have found EF. I have never, despite years of more than passing interest in health, (and,like the minds attracted to this space, everything else!)--found a public health forum such as this. The context of progessive sensibility here enables me to feel like I'm "home" when I get on.

--Sherrie ("Teacher Who Will Be at Seashore Tomorrow",and who has a long history of promoting thinking about things like kids/sandboxes...)

"But the risk of staying inside and reading science is zero." Not so. The risk is that you will become a boring old fart, far too grown up to revel in the joy of life's simple pleasures.Find a rock-pool at low tide,spot a little creature therein and, with a straight face, ask the missus for a jar to transport the little thing home so you can keep it as a pet.I dare you!

When they started digging up the dirt next door one lovely May day in order to build a new house, my husband went to inspect and promptly came down with a nasty case of bacterial pneumonia. Not to mention the friend who cut his finger while cracking open a holiday lobster the other day and the next morning his whole arm was swelled right up (currently on mega antibiotics). And that was after the lobster had emerged from boiling water that kills pathogens? Or the friend who was planting a garden, cut his finger, and... you know the rest. Big swelled arm. Amen for antibiotics.

From the seacoast of Slovenia I salute your "littoraly" pun! Is there acknowledged blogger shorthand for "Groan Out Loud"?

i dont understand


From "Littoral--of or pertaining to the shore of a lake, sea, or ocean." In the first paragraph of the post, our mischievous host is playing with words and our minds, bless him.