Monthly Archives: February 2010

A Chagas’ Disease Primer: Part 6

Chronic Chagas’ Disease

This is where the problem is.
Most people won’t get signs of acute infection, so they won’t know that they are infected.
In 70% of cases, that’s fine. As far as we know, nothing will come of that.

But the other 30%, anywhere from 10 -30 years later, will go on to develop chronic Chagas’ Disease.

Let’s review. We have our  assassin bug,

Triatoma dimidiata, important vector in Mexico

which transmits the single-celled protozoan parasite, Trypanosoma cruzi (in its feces)

A T. cruzi parasite, among red blood cells on a slide

The bug poop gets rubbed into a mucous membrane (like the conjunctiva around the eye) or the bite made by the bug.
Let’s look at the life cycle again:

For those of you who care, the trypomastigote is the infective stage, that is the stage that can be passed from bug to mammal and mammal to bug. The amastigote is the stage that multiplies in tissue.

Don’t get hung up on the names. It’s just to see that different stages do different things–one goes around to infect different cells, the other works inside the cells.

Detail of above diagram

Trypomastigotes have flagella, whip-like structures that allow them to move around, amastigotes don’t. On a blood smear you can see the trypomastigotes squiggling around among the blood cells.

Amastigotes seem to like replicating in the cells of the heart’s muscle.

That is not a good thing.


Public Poisoning of Dogs in Chile

I was a few miles above South America, flying on American Airlines flight 2110 (which was late, due to the airline’s inability to have the aircraft in proper working order before we left—local manager Claude Rains was shocked and had all of the usual suspects  rounded up and sent off), and pulled this letter to the editor from the Chilean newspaper, El Mercurio.

Why use man-hours when Strychnine can do the same work for a fraction of the cost?

Even with my Homer Simpson-like abilities in Spanish (“May I have a beer, please” is translated as “MAY I HAVE A CERVEZA, PLEASE”), I could tell that this article was about dealing with stray dogs with the abhorrent practice of poisoning by strychnine.

Strychnine is a potent neurological poison. Death from strychnine poisoning painful , prolonged (several hours), dramatic, and difficult to watch (don’t click if you are squeamish). The following description is from Wikipedia:

Ten to twenty minutes after exposure, the body’s muscles begin to spasm, starting with the head and neck. The spasms then spread to every muscle in the body, with nearly continuous convulsions, and get worse at the slightest stimulus. The convulsions progress, increasing in intensity and frequency until the backbone arches continually. Death comes from asphyxiation caused by paralysis of the neural pathways that control breathing, or by exhaustion from the convulsions. The subject will die within 2–3 hours after exposure. At the point of death, the body “freezes” immediately, even in the middle of a convulsion, resulting in instantaneous rigor mortis.

Of late, Chile has been considered one of the success stories of Latin America. Generally–but often mistakedly– we associate improved social conditions with better treatment of those less who are less able to protect themselves. Cruelty and callousness are contagious, and hard to eradicate. Strychnine poisoning is not the way to control the very serious problem of stray dogs and the diseases associated with them: rabies and serious injury from bites.

Sunday Lite

What lurks behind the fridge?

And is it a health risk?

Today’s Enemy

And she can lay 1000-3000 eggs.

The Brown Dog Tick

Rhipicephalus sanguineus, the brown dog tick

The interesting thing about this one is that it is found all over the world.  It can live its entire life indoors as well. One woman in Colan, where I just was, reported seeing a wall of a local house infested with hundreds of the things.

What I want to know, and what no one has been able to explain to me as of yet, is why this tick will go after dogs so aggressively, but tends to ignore other animals. What is it in the signals that a dog gives off that attracts this particular tick? Or what does this tick have that say, a deer tick doesn’t? The deer tick, Ixodes scapularis, is our usual suspect for the transmission of Lyme disease.

And now, the rankings of the most popular posts for the last 90 days. Clearly, Brigitte is leading the pack, followed by the life cycle for Trypanosoma cruzi. I am going to have to find a way to get Brigitte (of the 60’s, via a time warp) to talk to you about vector-borne disease. Sophia of the 60’s agreed to do it, but she didn’t fit in our time machine.

Un desafío para mis collegos de Peru (y otros paises de las Americas)!

Como Uds. pueden ver, no soy muy capaz de expresarme en español–lo considera una grand victoria que aprendí como poner tilde y accento. Pero, si queremos avanzar nuestra causa, es necesario que you tenga colaboradores de Peru y de otros paises de las Americas.
Por lo tanto, yo quería que alguién escriba para este blog in su idioma.

OK, Amigos?

“Owners” with their Dogs

Unlike the United States, where mothers become apopleptic if a kid runs out of view for a second during an outdoor game of hide-and-seek ( I’ve seen it, utter panic on the face of the Wellesley mom while her child was safely on the other side a tree), and we don’t let them out the door to just find their own play anymore (they have to have scheduled “playdates”, a word that still feels like sandpaper mixed with fish guts in my mouth), Peruvian kids are remarkably unsupervised and independent.
Many of the clients who brought dogs to the little clinic we held the other day were far under the age of giving informed consent. As this wasn’t part of any funded study, and we were helping everyone involved, neither I nor the Peruvians with whom I worked gave it a second thought. (Actually, I did give it a second thought, as evidenced by the this blog post. I have this little loop playing in the back of my mind: Richard, you should have refused to do anything with those dogs until the parents could come! Of course, the parents couldn’t come, which is why the kids were taking care of the matter.)

Where I stayed, the unexpected Brigitte Bardot connection, and a few pictures

Is Tick-Borne Disease Significant in Peru?

That’s what I’m here to find out. It certainly seems like it is present in the dogs. We had a lot of positive cases in the north.

The blood tests we ran

The dogs were treated for ticks and fleas, and given oral anti-parasitics against intestinal worms. The clinic was organized by the Asoc. Humanitaria San Francisco De Asis, which incidentally, receives money from Brigitte Bardot.

Ms. Bardot, in spite of being convicted 5 times for “inciting hatred” in France (against immigrants, apparently ), has a long history of working for the welfare of animals. Life is complicated.







This is where I stayed in Colan.

Who says they don´t love their pets in other countries?

Does this picture require narration?

Can I say third world anymore? (The rules change so often that I lose track)

This man drives a mototaxi (picture coming shortly), a three-wheeled motorcyle converted into a passenger-carrying vehicle. Fares are typically 2 soles ($0.68). There are hundreds plying the streets of Paita, the port town where this picture was taken.

The St. Francis of Assisi Humane Society of Colan set up a clinic. Dogs were given a dose of oral anti-parasitics and a spot-on treatment against fleas and ticks, and then agreed to have blood taken to check for heartworm, Lyme, and ehrlichiosis. Not surprisingly, their is no Lyme disease (that´s our disease), nor did I find any heartworm (mosquitoes don´t do well in the desert).

Are there other problems?

Stay tuned….