While I was visiting my study communities, the kids would often sing-song my name when they saw me. At first it was “Amanda foto [photo], Amanda foto” because I always had my camera on me. Then it was “Amanda camion rojo [red truck], Amanda camion rojo” because they liked my big red truck. And then it was “Amanda samook, Amanda samook“. Samook is the Nivacle word for ‘poop’. It’s okay, they weren’t bullying me, they were just really excited about fecal samples.
I was collecting fecal samples from study participants to see whether co-infections with intestinal parasites, particularly helminths (often referred to as ‘worms’), were affecting tuberculosis outcomes. Helminth-TB co-infections are particularly interesting for two reasons. The first is, people with helminths suffer from malnutrition and anemia; conditions which promote the progression to active TB and poor TB outcomes (Hotez el al 2006).
The second reason has to do with how our bodies invest their resources in our immune systems. The immune system has two major pathways for managing immune response: Th1, which is geared towards intracellular pathogens like Mycobacterium tuberculosis, and Th2, which is geared towards extracellular pathogens like helminths. People who are co-infected with helminths when they are diagnosed with TB have a cytokine profile that is biased towards the Th2 response (Resende Co et al 2006 [gated]). This suggests that when the body is already engaged in a prolonged fight against extracellular pathogens, it cannot put up a strong fight against an intracellular pathogen like TB at the same time.
I thought it would be a lot harder to convince people to give me fecal samples, but most people were really eager to take part. Partly I think it was because they have very limited access to clinical analyses and they wanted to take advantage of the screening. Analyzing fecal samples for parasites is time sensitive because the organisms and their eggs can only survive for so long outside the body and will break down. If someone living in a rural area, like my study communities, gave a fecal sample, it wouldn’t be usable anymore by the time it arrived at the laboratory unless a preservative like 10% formalin was added to the sample. The health regions where I was working only do fecal analyses for patients who are hospitalized or live near the clinical laboratory because they don’t have preservative.
Everyone had a pretty good sense of humour about ‘giving a fecal sample’ despite some initial concerns about how this transaction would take place. During the first part of the study I lost my voice while reading the consent form out loud over and over again. So for the second part, I pre-recorded my field assistants reading the consent forms out loud, one version in Castellano and one version in Nivacle, so we just had to hit the play button. When my field assistants got to the part about ‘giving a fecal sample’ during the recording, they could barely contain their laughter. I left it that way (instead of re-recording it) and I’m really glad I did, because people would laugh along with the barely contained giggles on the recording and would noticeably relax and joke around.
I distributed do-it-yourself fecal sample kits for people who agreed to participate: The sample containers (with the green lid) came from a local pharmacy, and I got a big discount for buying in bulk with my roommate’s loyalty card. I bought formalin from a medical supplier and diluted it to 10% myself, and spent a lovely afternoon aliquoting (portioning out) the preservative into the containers. A couple of items came from the grocery store around the corner from my apartment: a bandeja (paper tray) where the participants could ‘deposit their sample’ without having it touch soil or urine, and a tiny spoon they could use to transfer their sample into the container. I also gave a plastic glove to each participant so they didn’t come into contact with their sample or get splashed with the formalin (which can burn your skin). And I brought Ziplock bags with me from the U.S. (I couldn’t find them in Paraguay!), so the sample containers could be sealed inside and easily transported.
Some participants were a little embarrassed to turn their samples in at the health post, and they would wrap the sample container in coloured plastic or paper or scraps of fabric to hide its contents. I really liked the clear plastic bags because it was easy for me to quickly eyeball the sample and check that it was sealed properly and the patient ID and dates were correct. But if I were to do this again, I would try supplying paper bags to participants as well so they can conceal their samples.
Even with the preservative, the fecal samples are only good for about a week without refrigeration. It takes most of a day to travel between my study communities and the regional laboratory which was collaborating with me and doing the analyses. Which means I spent a lot of time on the road during my last 3 months in the field. Luckily, the health post in Integrationville was hooked up with electricity just before this phase of the study started, so I could store my samples in their fridge and make a run to and from the lab about every 1.5 weeks. I also had to time my visits to the lab so that the samples would arrive the day before the biochemist was free to work on them. This was kind of a pain because I was also collecting survey data at the same time and it made a mess of my scheduling.
Researchers often give gifts to the participants in their studies as a thank-you for their time, and my gift to people who participated in the individual tasks, which included giving a fecal sample, was a package of yierba mate and a photo. Both were really popular with participants, and several people joked that they could give me lots of fecal samples if they would get a package of yierba for each one!
In the next installment: what happens after the samples arrive at the lab.
Hotez PJ, Molyneux DH, Fenwick A, Ottesen E, Ehrlich Sachs S, et al. (2006) Incorporating a Rapid-Impact Package for Neglected Tropical Diseases with Programs for HIV/AIDS, Tuberculosis, and Malaria. PLoS Med 3(5): e102. doi:10.1371/journal.pmed.0030102
Resende Co, T., Hirsch, C. S., Toossi, Z., Dietze, R. and Ribeiro-Rodrigues, R. (2007), Intestinal helminth co-infection has a negative impact on both anti-Mycobacterium tuberculosis immunity and clinical response to tuberculosis therapy. Clinical & Experimental Immunology, 147: 45–52. doi: 10.1111/j.1365-2249.2006.03247.x [Gated]