2 key issues we think should drive this conversation: (1) The human #microbiome has been associated with a variety of diseases; how many of these effects are truly 'global'? (2) We need more efforts centered around the health concerns of populations in the rest of the world. 2/n
On issue #1 - We need to learn much more about #microbiomes EVERYWHERE. India and China have launched their own nation-wide initiatives; the @globalmicrobiom initiative is working on it too! My personal opinion: we need even more local efforts (*cough cough @Colciencias 🇨🇴) 3/n
Thanks to seminal studies by the labs of Drs. Dominguez Bello, Gordon, Sonnenburg, @ejalm, Lionetti, etc., we know that microbiomes differ greatly across the world. The largest differences arise when comparing populations in high-income vs. low- and middle-income countries. 4/n
And yes, using "high-income/middle- and low-income countries" instead of "developed vs. developing countries" was a conscious editorial decision. As a South American, I prefer this terminology - it is more quantitative and less loaded. Global South is another fave! 5/n
Side note- Our review is an opinion and does not include a comprehensive summary of differences in the microbiome across populations. This paper by Erica and Justin Sonnenburg highlights diffs btw what they call ancestral & industrialized populations: https://www.nature.com/articles/s41579-019-0191-8 6/n
There are MANY factors that drive these geographic differences in the microbiome (e.g. diet, agricultural dependency, C-sections). Several great studies have analyzed some of them across extremes. We think it's time to study them across wider spectrums. 7/n
What do I mean by that? Let's look at Colombia for example. Our diet is neither fully "Westernized" nor entirely plant-based. Our people live in both rural and urban areas, but urban for us isn't the same as urban in the US or Europe. See? It's complex! 8/n
Also, a popular approach in science is to group all middle-/low-income countries together. The problem with that: a lot of factors that shape the microbiome don't follow simple trends that can be divided that easily. #TrueDiversity #GlobalHealth 10/n
Let's look at a factor we think shapes the vaginal #microbiome: C-sections. Plotted is the rate of births by C-section worldwide (data obtained from @MamaDaktari - https://www.sciencedirect.com/science/article/pii/S0140673618319287). Even just looking across Latin America, it varies a lot within the region. 11/n
We'll learn lots by further diversifying human microbiome research! This year, 3 independent metagenomic approaches led by @cibiocm, @kyrpides, and Robert Finn reconstructed 1000s(!!) of previously unidentified bacterial genomes in populations outside of the US and Europe 12/n
What happens when you use those metagenome-assembled genomes instead of reference genomes? @cibiocm reported an⬆️in read mappability from 75% to 95% in Westernized populations compared to an ⬆️ from 45% to 85% in those of non-Westernized populations. 😱

These gut metagenomes also revealed the presence of eukaryotic organisms, which are more prevalent/abundant in people in the Global South. Often, #microbiome = bacteria, but we must ramp up efforts to understand interactions between microeukaryotes, bacteria, and the host. 14/n
On issue #2 - we know the #microbiome plays a role in resistance to infectious diseases like HIV, TB, and malaria. All in the top 10 causes of death for low-income countries. Thus, microbiome-based therapeutics have the potential to significantly impact global health. 16/n
Key questions: (1) How do intestinal (eukaryotic) parasites impact susceptibility to infections? (2) What about the microbiome and "neglected" tropical infectious diseases? (3) What if you're exposed to (or treated for) more than 1 infection? How does your microbiome shift? 17/n
Most of the research on the microbiome has been centered around non-communicable diseases (e.g. obesity, IBD, cancer, atherosclerosis). These are also on the rise in middle- and low-income countries but so few studies involve these populations. #GlobalHealth 18/n
Over the years, Jeff Gordon and his team have given us a masterclass on how to do just that in the context of malnutrition in both Malawi and Bangladesh. Their locally-driven work has led to the design of treatments such as microbiota-directed complementary food. 19/n
And then there's also the impact of migration on the gut microbiome. A couple of key papers came out this year on this very topic that is obviously really dear to my heart and of personal interest. #Immigrants #GlobalHealth #microbiome 20/n
I'll stop here for now but go read the paper! We also discuss some of the biggest challenges in internationalizing human microbiome research including capacity building, forming multi-national teams, sample transport, access to computational resources, etc... #ScienceForAll 21/n
A few things not in the paper that I also believe strongly: All over the world we need $$$ and to convince local governments to invest more in science (again... looking at you @Colciencias 🇨🇴). I think #scicomm will play a HUGE role in this, hence why I do #MicrobeMondays. 22/n
Who gets access to what journals? Will microbiome researchers in the Global South receive fair treatment in the peer review process at top journals? How about publication costs? How do we make the publishing process more equitable? #ScienceForAll 23/n
To wrap up: As the number of populations with characterized healthy and disease-associated microbiomes increases, it will become easier to identify patterns and shifts in composition or functional profiles that are common across the world or unique to specific populations. 24/n
Only then will it be possible to design microbiome-based health interventions applicable to most of the world’s inhabitants. As an engineer, it is key for me to remember that our solutions are only as good and equitable as the data we use to build them. 25/n
Finally, my research career has been completely transformed by dedicating all my time to tackling some of these issues over the last 2.5 years(the work will hopefully be out in 2020). Inclusion in research is about being able to see yourself represented in what you study. 26/end
You can follow @AnaMaPorras.
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