Tuesday, March 17, 2020

Coronavirus strikes training classes

The strategy behind today's protective measures of hygiene, social
distancing, and reducing human interaction is called "flattening
the curve".  This is why Extension programming is being
temporarily suspended.  Adapted from CDC/The Economist.
Who would have believed, even one week ago, that coronavirus would dominate our lives so quickly and severely?  This sort of thing is something that happens to other countries, not ours.  Yet here we are.

The reality of coronavirus hit home to me last week when we realized that we couldn't follow through with our plans to offer a long-planned mosquito control class as part of our IPM Experience House class curricula.  Texas A&M AgriLife and our local campus have moved to emergency mode, effectively shutting most training classes down for the foreseeable future.

In addition to IPM House classes, upcoming school IPM coordinator training courses are similarly affected.  We are cautiously considering whether we may be able to offer classes in May and June.

It took me a while to grasp the significance of the coronavirus shutdown strategy; but for what it's worth, here are a few facts and links that turned me around this week.

  • Understanding that the COVID-19 is not just another seasonal flu.  It's a disease with 4 to 7X higher mortality rate than the flu and longer persistence in the environment than the flu (up to 3 days on stainless steel and plastic).  Maybe worst of all, people (especially children) who catch it can be contagious without even realizing they are sick. 
  • We don't hear a lot about the plight of those who catch this virus and recover (not as gripping in headlines), but this is not a virus to take lightly. Early reports suggest the possibility of chronic lung impairment in some recovering COVID-19 patients
  • Yeah, it sounded bad in China, but look at Italy.  In Italy, where health care systems are more similar to our own but where quarantine actions were slow to be adopted, a crisis situation developed with lightning speed in emergency rooms of afflicted areas.  And if you think Italy's health care is inferior to our own, consider one statistic.  In hospital beds per 1,000 people, Italy leads the US 3.2 to 2.8.  Anyone thinking that our doctors and hospitals could do better in the face of overwhelming numbers of cases as in Italy would be wrong. 
  • Thankfully, there is a strategy behind the "stay at home" message we are hearing so much about. It's called flattening the curve, and it's based on the impact that self isolation and social distancing can have on the speed of spread of COVID-19.  While it may seem inevitable that some of us will get the virus, by reducing our exposure to others we can slow the rate of virus spread.  And if we do this, we might be able to spare our health care system the tsunami of cases seen in Italy. 
  • Our country rightly invests billions of dollars each year in science and health care.  It's time to listen to those smart folks who have dedicated their lives and their intellects to understanding health and illness and the spread of disease.  They don't know everything, of course, but they know a lot more than us non-health professionals know.  
So for all these reasons, I am working this week in an empty building with plenty of social distance around me. We use hand sanitizer, wash our hands regularly and stay away from large gatherings including, unfortunately, classes where we might otherwise be training some of you.  

Let us pray for our communities and our nation, and look forward to celebrating a return to face to face interactions in a matter of weeks.  Be assured that our IPM training classes will resume as soon as possible. 

Loving it with fleas

I love my job--especially when I get to identify tiny insects that no one else wants to look at. I recently received an insect from a gentleman whose daughter had been bitten at home. I could tell immediately we were dealing with a flea--usually a routine identification to confirm that the tiny insect was a cat flea.  But this specimen was different, and prompted a closer look. What fun!

Before I let the "cat flea" out of the bag, one of the fleas below was the flea I saw this week. Can you identify which is the one that was not a cat flea? (Hint: it doesn't have anything to do with the color, length of the body, or shape of the flea)

Two adult fleas.  Human flea on left, cat flea on right.
Click on image for a better view.  Photos by M. Merchant.

If you guessed the flea on the left was my mystery flea, you'd be correct.  But did you guess right for the right reason? 

First, it wasn't the legs.  Both fleas are "host fleas", which means they live most of their adult lives on a host.  Host fleas must have strong jumping legs to gain access to this host.  Nest fleas, on the other hand, live in the nests of their hosts (usually rodents or birds), only living on the host long enough to take a blood meal and returning to the nest after dinner.  Nest fleas rely less on jumping and and more on crawling within the nest to feed, so the third pair of legs is more like the second pair in size. 

The big difference between these two fleas is the presence or absence of dark, comb-like bristles on the face and behind the head.  The cat flea has combs both above the mouth (called a genal comb) and on the tail-edge of the first thoracic segment (pronotal comb) behind the head.  Fleas with both genal and pronotal combs are relatively rare, narrowing down their probable identity considerably.  Most fleas found indoors with two combs like this in homes are either cat fleas, Ctenocephalides felis, or dog fleas, Ctenocephalides canis

The flea on the left lacks both a genal and a pronotal comb, ruling out cat flea.  This flea is a human flea, Pulex irritans.  The human flea, like the cat flea, has many potential hosts including small mammals, canines, pigs, humans, and even burrowing owls. 

Entomologists have identified over 2,500 different kinds of fleas from around the world.  Most of these fleas are highly fussy about their food, feeding on the blood of only one or a few closely related kinds of hosts.  These two fleas are exceptions.  Besides cats, the cat flea gladly feeds on dogs, opossums, raccoons (two frequent wildlife hosts that can bring fleas into homes when pets are not present), foxes, skunks, cattle, rats and rabbits, to name a few. [Curiously, squirrels do not seem to be a listed host of cat fleas, so are not likely to be the source of fleas in homes with no cats or dogs.]

Why worry about flea identification?  Because flea ID may provide clues to a possible source of a flea problem. If fleas found in a home or on a pet are not cat fleas, it's possible that the fleas are coming from rodents or other wildlife.  For example, rat fleas may suggest a rat or mouse infestation.  Rat fleas may pose greater risk for the homeowner from flea-borne illness such as murine typhus, or even (more rarely) plague, though the cat flea is not without its own risks. Cat fleas on opossums have been associated with increased cases of murine typhus in California and Texas and other areas.  Cat scratch disease may also be carried by cat fleas.

The following key is provided by the Centers for Disease Control (reprinted in the Mallis Handbook of Pest Control) and can help you identify some of the more common fleas found in structures or on pets. Combs can usually be seen by the practiced eye with a good 10X handlens.  If you want to see other features in this key, however, you'll need a microscope.  A 12X magnification will show genal and pronotal combs; but 25X to 50X is needed to see smaller characters shown on the key. 

If you do not see pronotal and genal combs on a flea collected in a home, and do not have a good microscope, it's best to save some specimens in either 70% ethanol or rubbing alcohol.  Specimens can then be sent to an entomologist for positive identification. Five or more pointed teeth on both the genal and pronotal sites will narrow any flea found on a pet or in a building down to a cat or dog flea, both of which have similar host ranges and control measures. 

CDC Pictorial key to adult fleas
Click on key for a better view. 

 Next time you get your hands on some fleas, take a closer look. Check for combs and use the key. I predict you'll get that same thrill of satisfaction entomologists get when being able to put a name on something that most people can barely see. Your customers will be impressed too.