I think we all understand the idea of how to trace HIV transmission – by sequencing the viral genomes of different strains and looking at differences, we can map the phylogeny of the different strains. In doing so, we can see who infected who. Here’s an article that summarizes this pretty well.

I thought this was pretty cool because when HIV-positive individuals are told about using condoms and how that prevents infection of HIV-negative individuals – but less often do you hear about preventing transmitting another strain to an already HIV-positive individual. The consequence of infecting an already infected individual is introducing, to some extent, a new virus. Depending on viral loads, re-infection might actually change the viral population dynamics and introduce new mutations and phenotypes to the viral landscape in the individual. The primary consequence of this is that re-infection may lead to drug resistance and dramatically affect treatment course.

I didn’t know to what extent this idea of super-infection was known among the population, but this study shows that the possibility is actually very well known. While this all seems pretty logical and understandable,  I can’t help but think about what this means in the realm of public health – How does this affect how health professionals counsel people living with HIV/AIDS (PLWHA)? Should we treat couples together, regardless of HIV status? Should we sequence strains to see where individuals were infected and use that to develop specific prevention strategies?

Although it was awhile ago, the discussion we had about birth in class stuck with me. As members of our cultural society, it’s difficult to differentiate between what’s actually true and what we think is true because of culture. In class, someone mentioned breech babies and how that position necessitated a cesarean section – but it doesn’t. Health and medicine in general have become very medicalized. Normal development processes like  menopause are now considered “conditions.”

This article provides a concise overview of why cesarean section births are on the rise. In class, Nelle had provided an example of how cesarean sections weren’t always the best option. The pressure involved in passing through the birth canal actually helps remove amniotic fluid from the baby’s lungs. Therefore, when a baby is delivered surgically, he or she may go on to develop issues like asthma and other respiratory challenges – all because of the manner in which he or she was born.

When researching the other benefits to a vaginal delivery, I came across one noteworthy example. Throughout the semester, we have talked about gut microflora and its influence on an individual’s health. Well, there’s evidence that supports the idea of a cesarean section  birth may stunting development of gut microflora. From other readings, we know that gut microflora influences digestion, metabolism, cardiovascular health and more. Additionally, babies born vaginally had gut microflora similar to that of their mother’s, while babies born by cesarean section had gut microflora similar to the bacterial colonies found on skin surfaces. I’m sure there are numerous other effects of delivery mode on both the mother and baby’s health outcomes. I think it’s important to be informed with evidence-based research, primarily because as we saw in class, we are all dramatically influenced by culture.

Here are links to the two articles I found:
1. http://journals.lww.com/jpgn/Abstract/1999/01000/Fecal_Microflora_in_Healthy_Infants_Born_by.7.aspx
2. http://www.pnas.org/content/107/26/11971.short

In class, we talked about obesity and the multiple mechanisms of causation and how both genotype and phenotype influence the development of metabolism and progression to obesity. Essentially, there’s a full gambit of biologically tested influences  when it comes to obesity. In addition to the complex physiological components, obesity is so heavily saturated with social expectations, cultural meaning  and structural impacts. When discussing the option of classifying obesity as a disease, we primarily focused on the ideological and medical consequences – How is a disease defined? What are the required components of a disease? How would such a decision affect the “treatment” of obesity? How would it affect health insurance and payment?

An aspect we didn’t really discuss was the effect of such a classification on the public. Other questions we could have asked include: How would someone react to obesity if it’s a disease? What does that mean for healthy lifestyle choices? What does that mean for preventive care initiatives? If it’s a disease, is there a cure? What is the cure? A NYT article and journal bulletin discuss the psychological impact of classifying obesity as a disease.

“Specifically, obese participants who read the ‘obesity is a disease’ article placed less importance on health-focused dieting and reported less concern for weight relative to obese participants who read the other two articles. They also chose higher-calorie options when asked to pick a sandwich from a provided menu. Interestingly, these participants reported greater body satisfaction, which, in turn, also predicted higher-calorie food choices. ‘Together, these findings suggest that the messages individuals hear about the nature of obesity have self-regulatory consequences,’ says Hoyt,” (APS, 2014).

Over the last couple of weeks, we’ve been discussing the importance of an evolutionary understanding of medicine, health and disease, and we often talk about the advantages of comprehending the ultimate explanations of fever, malaria and more. But at the same time, we also consistently ask what this information means to the average patient. Does an individual need to understand the complex relationship between melanin, sun exposure, and vitamin D when getting diagnosed with skin cancer? Does an individual need to know the thrifty phenotype hypothesis to better understand his or her obese state? Does providing an evolutionary reasoning for the condition make the suffering more bearable? Does it change the individual’s perception and though process when it comes to treatment and lifestyle choices? The above cited articles demonstrate a very possible disadvantage to the classification of obesity as a disease. We have to ask ourselves: how much does a person need to understand and what are the associated advantages and disadvantages to that understanding?

I remember in one of our class discussions, lactose intolerance came up and I thought that a change in the lactase (the enzyme that breaks down lactose or milk sugar) gene made it possible for expression after weaning. This meant that individuals could digest milk and other dairy products and supplement their diet with other sources of calcium and vitamin D. To me, that seemed a completely sufficient explanation for why the new allele for lactase was selected as advantageous. After all, we’re all told to drink milk to build strong bones, so why wouldn’t the same apply to early shepherds. This explanation is known as the “Calcium Assimilation Hypothesis.”

We need vitamin D to absorb calcium. That vitamin D can come from one’s diet or come from sunlight. So in geographic regions of less sunlight, there is a greater need for a diet containing vitamin D than say in equatorial regions. In other words, the Calcium Assimilation Hypothesis really only holds for northern European populations. 

From here on out, I think it’s important to consider lactose intolerance as more than the digestion of milk, or more specifically lactose, but as an evolutionary culmination of culture, geography, and sunlight.