Field epidemiology in Tumbes, Perú - Investigation and Deduction Among Uber Nerds

the view from my hotel room.
days have been so busy we haven't had time to enjoy the beach yet!

Greetings from Tumbes!!  I'm in the the smallest district in Perú, about 10 miles from the border with Ecuador, and I'll be spending the next week here!!  This area has a nice, warm climate, with gorgeous beaches and landscapes.  It is dotted with rice fields and palm plantations and is home to one of the most famous mangrove sanctuaries in the world.

rice field in Tumbes

Unfortunately, Tumbes is also endemic with malaria and dengue fever.  We are here for a field epidemiology course, learning applied skills on everything that goes into an outbreak investigation.  Today is day 5 of the course, and while I am very exhausted from 6 hours of sleep every night and long days, with meals spread very far apart, I have to admit that this has been the most interesting part of my trip to Peru so far.

we found larvae in this water tank in a woman's backyard.
she lives by herself and is unable to clean the tank out on her own. 
(photo credit: Amit Kumar)

In the last few days I have learned a great deal about vector-borne and infectious diseases.  Two days ago, we split into teams and went door-to-door in a local community with reported victims of dengue fever to try and find more cases and determine if they are experiencing an outbreak.  We conducted the surveys we created (in Spanish), asking about whether household members were experiencing symptoms specific to dengue fever and malaria (such as fever, chills, abdominal pain, diarrhea, and body aches), along with some other questions.  For the most part, people were very keen on allowing us into their home to interview them, examine their water tanks, and take samples of their blood (if they were showing symptoms) or their water tank (if we found mosquito larvae).  

trapping mosquitoes near a pig pen
(they like animal smell)

By the way, mosquitoes are pretty crafty and resilient creatures that can do a lot of damage if their presence isn't controlled.  For example, the female Aedes Aegypti mosquito, which transmits dengue fever, bites humans during the day (contrary to what most local people think) and resides near their homes, laying its eggs in places like water storage tanks or near pools of stagnant water.  These eggs can last up to a year without water. Once they do find stagnant water, the eggs hatch into larvae and eventually develop into mature, dengue-spreading mosquitoes.  

looking for Aedes Aegypti larvae and pupa in a
community cemetery (there were definitely
households within 50m of this area)

We spent the better part of today dumping water out of ad-hoc flower pots in the local cemetery, where we found ridiculous amounts of Aedes Aegypti larvae and pupae flourishing.  Despite the fact that water is strictly forbidden in the cemetery, the local people desire to pay respects to their deceased loved ones, and leave flowers in water for their relatives on a weekly basis. If community members do not routinely clean out their water tanks or eliminate areas where water can stagnate, especially during the rainy season, they are at extremely high risk for contracting illnesses like dengue fever. It only takes one infected person and a female Aedes Aegypti mosquito for an outbreak to occur, as the mosquito spreads the disease to all its victims once it bites an infected individual.  These mosquitoes can cover up to a 50 meter radius from their larva pool.  And that's just one type of mosquito!!!!

Anopheles pupae

more larvae trapping!

We've also collected larvae and pupae of the Anopheles species from a nearby farm with a very polluted stream running around the perimeter.  The female Anopheles transmits malaria to its victims, and likes to bite them at night.  The differences between these two species are subtle but significant.  It basically means that humans in these tropical climates are quite vulnerable to contracting vector-borne diseases at almost all times of the day, and are even more vulnerable if they are impoverished and cannot afford preventative measures like insect repellant, mosquito nets, and well constructed housing that keeps vectors out.    

trapping live, adult mosquitoes for dissection!!

In summary, the two biggest things I've taken away from this course and my time in Tumbes so far:

1.  A new-found awe for mosquitoes and all the havoc they cause, as well as other crazy, disgusting infectious parasites

2.  A fascination with field research and epidemiology (and potentially a new career path if I can play my cards right)

Stay tuned for a post on Cysticercosis and photos of animal necropsies (nerd alert!).