What is up with West Nile virus this year?

It has been a bad West Nile virus (WNV) season, the worst since the virus arrived on the continent in 1999, and it isn’t over yet. But why? Why Texas, and even more curious, why South Dakota? WNV is a mosquito-born virus, but so is malaria and we don’t have malaria in the US anymore.

To understand the epidemiology of WNV we have to look at nature. It turns out that humans are “dead end” hosts, meaning we aren’t the intended target. That’s because we don’t sustain a significant viremia (meaning there is lots of virus circulating in the blood as happens with malaria for instance). Mosquitoes don’t pick up virus from us to transmit it to others. WNV is a virus adapted for birds and the normal cycle is that an infected mosquito bites a bird. The bird becomes viremic, other mosquitoes bite the bird and perpetuate the cycle. This is how the virus “amplifies” over the summer months.   Most of these mosquitoes specifically feed on birds and don’t bite humans, but there are crossover mosquito species, omnivores if you will, with a taste for bird and human blood. They come into the picture late in the season when the cycle has amplified the virus to infect many birds. Crossover occurs, the omnivores bite birds, pick up the virus then bite humans.  This is why we see most of the cases of WNV in late August and September. Amplification takes time.

Believe it or not WNV mostly causes an inapparent human infection. Only two out of ten get sick, and most of those get a flu-like illness. About one in a hundred get the more serious version, called “neuroinvasive disease.” This is a brain infection that causes weakness, confusion, coma and even death.  Age is a risk factor with 55 years seemingly where the increased risk begins, but anyone with a health condition that impairs the immune system should consider themselves at risk and take precautions when outside during mosquito season.

Mosquito control includes the use of larvacides-chemicals that kill the non-flying stage of mosquito – early in the season and adulticides throughout the season. Adulticides are chemicals that kill the flying adults.  We all remember spraying from when we were kids and chased the fogger down the block on our bicycles (well, some of us remember.)

So what’s a person to do? If you own a home make sure there are no items in your yard that could collect water and serve as a breeding sites for mosquitoes. Ensure that all windows are secure and screens intact. Don’t leave your door open. Peak mosquito biting hours are dusk and dawn but also anytime in between. Permethrin-based repellents can be applied to clothing but not skin.  Long sleeved shirts and pants, if made of thick material can deter bites, but it has been really hot throughout most of the US this summer.  The best put-on-the-skin repellents are DEET and Picaridin and the duration of effectiveness depends on the concentration. DEET can be toxic to small kids, so apply with caution. Oil of lemon eucalyptus is another alternative. CDC’s advice on mosquito repellent use is here: 

http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm

Back to why is Texas and South Dakota having so much West Nile? The answer is nature. The right combination of rain and sun increases food supply for birds. If there are more birds, there is more food for mosquitoes and then more mosquitoes. Amplification of the virus is increased. The weather and rain also impact on mosquito breeding and hot weather means a higher amount of WNV in mosquitoes. If there are a lot of juvenile birds of the right species, birds that haven’t had been infected with the virus before, then that is the perfect storm. I haven’t been to Texas or South Dakota but I bet there has been an increase in young, naïve birds capable of sustaining the WNV and a bumper crop of all mosquitoes, including the crossover biting ones.

The fallacy of IT security

Forgive me readers for it has been many weeks since I have last written. It is not because infectious diseases have gone away. To the contrary, there is a new new flu virus, H3N2v that has emerged again in pigs and has caused some recent furor though thus far the illness is mild. There have been more iatrogenic outbreaks related to poor infection control and there's even an Ebola outbreak in Uganda with 23 cases and 16 deaths. No info on how the outbreak began though. The reason I have taken a hiatus from the blog is to focus on the new novel and it occupies all of my writing hours.

But when something sticks in my craw I just have to get it down on cyber paper. At work, the latest bureaucratic brainstorm is to require password changes for the application we use to log our time every three months. I want to know if anyone had ever suffered a breach. Really, who would want to crack into this system? Perhaps to steal some sick days? I bet they go for a few hundred apiece on the black and blue market.

Let's see, now I have at least three or four other work related passwords, all of which expire far too frequently, then there's email, twitter, bank accounts... soo many that I've had to write them all down.  In the same location in fact, so that I have them handy in case I forget. Check that multiple locations. But wait, doesn't that defeat the purpose of having expiring passwords?

Yes, it most certainly does. WTF?

Not AGAIN! Hepatitis C caused by a medical procedure

The New Hampshire Department of Health is reporting ten cases of nosocomial hepatitis C associated with a cardiac cath lab. What is unusual about this outbreak is that it is in a hospital where infection control is generally more rigorously practiced. While the exact route of transmission in this outbreak has yet to be determined, public health enemy number one has to be suspected.

http://www.fosters.com/apps/pbcs.dll/article?AID=/20120606/GJNEWS_01/120609858

In May of 2001 we did our very first hepatitis C outbreak investigation. A doc in Brooklyn reported himself after he found four of his own patients hospitalized with acute hepatitis C while on hospital rounds. He had done endoscopy on all four within the recent past. Endoscopy, more specifically colonoscopy, is recommended for screening and prevention of a big killer, colon cancer.  It is an important medical procedure, but it has risks. One of which shouldn’t be a risk, hepatitis C. When performing colonoscopy the physician reuses the equipment. That was our first suspicion and while the steps to clean the instruments didn’t follow the exact manufacturer’s instructions, we quickly ruled out the scopes as the cause. We had uncovered twelve patients over a five day period, many of who had their procedures back-to-back. There simple wasn’t time to reuse the scopes. We next zeroed in on the other invasive part of the procedure, anesthesia. We quickly discovered that all the patients had received the same drugs in about the same quantities, but what really stood out was the vials. They weren’t single use and thrown away. Meet the multi-dose vial (MDV). Intended for a single patient, these are often used for multiple patients. Why? They cost less. But it shouldn’t be a problem. As long as they are always entered with a clean needle, that is. Unfortunately, that isn’t what happens. The medical literature is littered with outbreaks traced to MDVs. We determined that a patient known to be infected with hepatitis C underwent colonoscopy. He woke up during the procedure. The anesthesiologist removed the needle and syringe that had been bathing in the patient’s blood and reinserted this into a MDV. The bottle was then used for the next fifteen or so patients, infecting twelve of them with the virus.

So, what’s the answer? For the consumer ask your doctors if they use MDVs and request that you get a fresh vial and it is thrown away when done. For us doctors, don’t use MDVs. For the FDA prohibit MDV use without appropriate engineering controls which eliminate the possibility of  accidental needle reuse. Hepatitis C is preventable. 

Mycobacterium chelonae outbreak

A cluster of infections due to Mycobacterium chelonae have been diagnosed in individuals who patronized the same upstate NY tattoo parlor. The outbreak was traced to a bottle of pre-mixed ink and the FDA is issuing a recall. 

For information on tattoos and mycobacteria infections see:

http://findarticles.com/p/articles/mi_hb4393/is_1_42/ai_n56785728/

and

http://www.ncbi.nlm.nih.gov/pubmed/19733936

Interview with Mailaise author Don Weiss

Detectologist: What made you decide to write this book?

DW: I had written a chapter on the anthrax outbreak for a non-fiction book on outbreak investigations by Mark Dworkin and came across a number of interesting conspiratorial coincidences that I thought would make a good novel.

Detectologist: Conspiracies? What do you mean?

DW: Well, for instance, two of the 9/11 hijackers lived for a while in South Florida near the first anthrax case. On the same day the case was announced on October 4, 2001, an Ukrainian missile shot down a Russian commercial airline over the Black Sea. On board were microbiologists from Novosibirsk. And after the attacks there was a series of deaths of other microbiologists, some of whom were involved in bioterrorism research.

Detectologist: Fascinating. What was it like during the actual outbreak?

DW: Did you ever do wind sprints in high school? Running back and forth over the length of the gym floor as fast as you can stopping at the foul line, mid-court, three-quarter court and then full court? We worked long hours after the 9/11 attack doing surveillance for a secondary biologic attack. After that the anthrax response was like doing a fifth, sixth, seventh and eighth wind sprint.

Detectologist: How did you cope? It must have been nerve racking.

DW: Humor, but I think writing the novel was a way for me to bring some closure to the experience.

Detectologist: The book matches up an epidemiologist with an FBI agent, how close to reality is this?

DW: During the anthrax outbreak we did work closely with an FBI agent, and one of our staff was assigned to be the liaison with law enforcement. Mailaise does expand on this a bit.

Detectologist: Where did the inspiration for the epidemiologist, Mackey Dunn and the FBI agent, Charo Chen come from?

DW: The characters are composites. A mix of the many people I’ve met, worked with and known over time. I think it is necessary skill for writers to be observant. As a friend of mine used to remind me, if you aren’t constantly amused it means you aren’t paying attention. A lot of my ideas come from everyday situations.

Detectologist: You decided to self publish through Amazon services. Can you share some of your experiences?

DW: Sure. I started Mailaise in 2007. Two and half years, and several re-writes later I began contacting agents. I got very little interest.  After Mailaise won the Herdsfolk First Novel Award I found an editor to help me polish it some more. I tried again with agents, got a bit more interest but no takers. The publishing business has become highly competitive, with the poor economy and the expansion of ebooks, agents and publishers are very selective.  I have so many ideas for stories I felt like it was time to be done with this one and move on.

Detectologist: So, what’s next? Are you working on a sequel?

DW: Yes. I am close to completing the first draft of a sequel in which Mackey and Charo investigate a smallpox outbreak in New York City. Then there is the unfinished first Dunn novel and a novella I wrote between books. I have no shortage of ideas.

Detectologist: Very interesting, I look forward to reading the sequel; what’s it called?

DW: It’s a historical mystery called The Curse of Cortes.

Still no flu this winter but there's soup

Butternut squash split pea soup

1-1 ½ cups dried split peas

1 lb butternut squash

1 roasted red pepper (skinned and diced)

1 bulb of garlic, roasted, peeled and chopped (should be soft)

¾ cup frozen corn

1 tsp vegetable or chicken stock (I use Better than Bouillon brand)

1 tsp granulated garlic

1 tsp granulated onion

1 tsp black powder

1 tsp savory

Pinch sea salt

3 cups water

Boil peas in 3 cups of water and stock until mushy (add more water if necessary). In a separate pot steam sliced squash until soft. Remove squash rind and mash. Roast bulb of garlic until soft and red pepper. Add squash to the peas. Add garlic, chopped red pepper. Season to taste with spices. Add more water to desired consistency.  Add corn.

Influenza that fickle fellow

While influenza epidemics occur annually the variation in the timing, peak and magnitude remain a mystery. So far influenza in NYC has been mild. Several surveillance systems are used to gauge the severity of flu season and by any of them either flu hasn’t arrived yet or the strain has not varied much from last season. Outpatient visits for influenza-like illness in NYC are still below the 2.5% threshold and of nearly 1800 lab tests done for flu in the first week of 2012 less than 20 were positive (during peak flu season this can range as high as 15%). Elsewhere in the country the story is much the same with only a few states showing activity, but no hot regions.  Most of the circulating strains are the H3-type with smaller proportions of H1 and B; all components of this year’s vaccine. Looking at the world picture there is activity in Northern Africa and Japan, however, in general activity remains low.

It is still a good idea to get a flu shot, especially if you have a chronic illness. 

http://gis.cdc.gov/grasp/fluview/main.html