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The objectives of my PhD are (1) to characterize the contaminations by human enteric pathogens involved in acute gastroenteritis (AGE) of water, air and leafy vegetables eaten raw in / around Bogotá (Colombia), and (2) to assess the resulting microbial risks for the population according to education, living conditions and individual practices (food, hygiene, health). This work have required the prior development of a method for distinguishing between total noroviruses and infectious noroviruses.

The Colombian context is specific from several points of view:

• First, less than half of Colombian municipalities have wastewater treatment plants (WWTPs), many of which only perform pre-treatment. About one third of Bogotá's wastewater is pre-treated, while the rest is discharged into the Bogotá and Tunjuelito rivers without treatment;
• Second, the intake of vegetables and fruits is largely limited to a handful of relatively inexpensive products, some of which are irrigated by fresh surface water heavily contaminated with faecal indicators and human enteric pathogens;
• Third, disposing in open landfill of soiled toilet papers and soiled diapers for babies and adults presents a priori potential risks of aerosolization of human enteric pathogens.

Between July 2017 and November 2018, I monitored the contamination of (i) tap water, river water, storm-water, treated lixiviates from Doña Juana landfill, and irrigation water, (ii) leafy vegetables (chards) from production to the merchants' stall after handling, and (iii) outdoor air above the landfill, on the terraces of houses in / nearby Bogota neighborhoods, and in a few other places. E. Coli was used as a faecal indicator, while total coliforms (T.C.) without E. coli were used as an indicator of environmental contamination. Pathogens included human noroviruses GI and GII, rotaviruses, salmonella spp., shigella spp.and cryptosporidium spp..

Between September and December 2018, a survey was carried out among 133 households in the neighborhoods of Usme district which are the closest to the Doña Juana landfill on their cases of acute gastroenteritis (AGE), their education level and living standards, and their food, hygiene and health practices.

The main results already include (1) a new method for producing or enumerating infectious human noroviruses, (2) identifying the most critical points with regard to indirect transmission of AGE, and (3) a first analysis of AGE transmission between / within households. The epidemiology of AGE seems to distinguish La Aurora neighborhood from the other neighborhoods explored, and I am currently researching the factors that could explain these differences. 

I hope to finish writing my PhD thesis in late February 2020 for an oral defense in late April or early May 2020.