Pereira, Karen

School of Public Health



Spatial analysis of determinants influencing diarrheal disease

Norovirus (NV) is the leading cause of gastroenteritis (GE) in the world and is estimated to cause 200,000 child deaths per year. NV is second only to rotavirus as the cause of dehydrating childhood GE and hospitalizations. With widespread rotavirus vaccination, NV is likely to become the leading cause of pediatric GE. Nevertheless, community-based data on NV epidemiology and immunology are lacking, especially for pediatric populations. Such data are essential to the design and effective use of NV vaccines. Sapovirus (SV) is another enteropathogen that has caused severe hospitalizations.
 Given this context, our research team is initiating a longitudinal birth cohort study focusing on correlates of disease severity and protective immunity. The primary goals of the study is to characterize the epidemiology of NV and SV in Peruvian children by quantifying infection, symptoms and genotypes, and to quantify the impact on malnutrition and linear growth. Participants will be followed from birth to three years using systematic collection of data and specimen. In addition to data on health outcomes, demographic, socioeconomic, and geospatial information will also be collected for study households. This provides an excellent opportunity to use spatial analysis to explore how community and household characteristics have effects on enteric infections and malnutrition during childhood.
The study site is a peri-urban community located outside of Lima, the political and economic hub of Peru. Over the past several decades, pueblos jovenes, or shantytowns, have been established by Peruvians immigrating from the rural Andean highlands who settle on unauthorized plots of land. Over time, these shantytowns gain recognition from the government and slowly receive access to services such as electricity, water, and sewage. The impoverished and unhygienic conditions of most of these homes lead to high rates of childhood diarrhea among slum-dwellers. This is a serious public health problem provided that those afflicted by severe childhood diarrhea may endure lifelong issues including malnutrition, growth stunting, decreased immune function, and impaired cognitive development.

Global Health Mentor/PI: Robert Gilman, MD

My Global Health Established Field Placement was in the community of Oasis, in the peri-urban district of Villa el Salvador, in Lima, Peru. As part of Bob Gilman’s team, my duty while in Lima was to collect the GPS coordinates of the houses enrolled in his previous diarrhea study looking at norovirus, while establishing routine GPS coordinate collection for the houses enrolled in his current diarrhea study looking at norovirus and sapovirus. Upon my return to the United States, my responsibility was to conduct a spatial analysis on diarrheal incidence in the community of Oasis. This placement was exactly what I was looking for as it gave me the opportunity to not only have more experience in the field but also see a project through from planning to data collection to data analysis to drafting of a manuscript. My time in Lima provided me with the chance to apply my knowledge of biostatistics, epidemiology and infectious diseases from class to a real-world problem.

Each fieldworker was responsible for a different zone within the Oasis community, so I accompanied 4 different fieldworkers during their routine visits to collect these coordinates. After this, with the help of Jess Rothstein, the PhD student also working at the site, I set up a training session for the fieldworkers using a GPS data collection protocol I had developed. During this training session, under the supervision of our field coordinator, I explained how and why GPS data collection was helpful in public health, reviewed the protocol with the fieldworkers and let them practice recording GPS coordinates. After the training session, I continued to accompany the field workers as they visited the houses enrolled in a new cohort study and recorded the GPS coordinates for each household, I simply watched to ensure data collection and recording was occurring according to protocol. With the exception of the houses enrolled prior to July, GPS data collection for the ongoing diarrhea study on norovirus and sapovirus will occur at the time of study enrollment.

As we went from house to house I couldn’t help but notice how although all of these families are well below the poverty line, the majority of houses had big screen TVs and entertainment systems. The fieldworkers explained to me that this was the case because most families use electronics as a want a glimpse of happiness or a distraction from their real lives and electronics also provide some indicator of wealth. This observation prompted several discussions, on peri-urban communities, migration in Peru, and the slow process to receive basic water and sanitation infrastructure in these communities, and their effect on the health and wealth status of community members. This newfound knowledge from the fieldworkers prompted me to alter my study in a way that tried to incorporate the effect of migration and the development of these communities on diarrheal incidence.

I’m not normally a shy person, but I didn’t talk much the first couple days I accompanied field workers on house visits, as I didn’t really know what to say and I was self-conscious about my Spanish, mainly my accent. As the days progressed, I began talking more and more, and my Spanish was not only improving but I was getting beyond the small-talk with my fieldworkers. I am so thankful for those friendships because not only did conversation make my often long work days easier, but I also was able to see how hard and long these women work to provide us with data to conduct studies, while also having families they needed to take care of when they weren’t working. Every day, all the field workers would wait until the last field worker returned and the last sample was processed, to clean and set the table, and take turns heating up each other’s food. Although we brought our own lunches, food was often exchanged, and there was always an engaging conversation over a cup of coffee or tea. Lunch was a true break from work to enjoy a meal and the comradery of co-workers, and this struck me as incredible and something I have never experienced in a work environment in the US. I feel as if lunch time with the field workers sums up my field placement experience as it was a moment to be part of and form friendships within a team that was made up of women from all walks of life, and left me energized to go conduct my own field research while learning the importance of of field research in public health.


September 2020



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