Dr. Mina was a guest lecturer to our class soon after India announced the eradication of polio! Many interesting questions came up in discussion that class period. The question that interested me the most was, ” What impacts will this data have on the anti-vaccination campaign?” . I think we can all agree that individuals against vaccination will definitely use Dr. Mina’s research to support their claims.

I think an important part of acquiring data like this is to make sure that the public is properly educated. I think that the greenmed article we read for class improperly relayed the data to the public. The data was used out of context in order to strengthen a personal argument. This is one reason why I do not agree with the CDC’s decision to no longer support Dr. Mina’s research. The CDC, as a highly respected health organization, has a duty to properly educate the public about new information regarding vaccines. After that, it is the personal opinion of the individual to take a stance in regard to vaccines.

In this blog post I just wanted to provide some information on how polio eradication was achieved in India. Vaccinations were a huge part in this achievement:

Polio is a highly contagious virus that affects the nervous system (WHO). The virus is spread through contaminated water which is pretty abundant in impoverished areas of India. Polio has been a challenge to eradicate in India because of many reasons such as a high population density, poor sanitation, and low rates of routine immunizations (Gates Foundation).  India has been well on its way to the eradication of polio for some time now. A small child, Rukhsar Khatoon, was India’s last reported polio case in January of 2011 (CNN Health). The surveillance of polio proved to be a very important step in India’s eradication process (WHO). The surveillance strategy helped to pin point which populations had a greater risk of polio (WHO). The National Polio Surveillance Project was started in 1997 (WHO). They started by supporting early detection as well as testing stool samples of children who had recently become paralyzed (WHO). Later, environmental surveillance proved to be one of the missing links in the surveillance system (WHO).

Immunization efforts were also a big part of India’s success story! Innovative ideas on how to keep the polio vaccine refrigerated were a major part in the success of immunization (CNN health). There are many parts of India without electricity which presented a major issue in attempting to vaccinate rural villages (CNN health). The solution to this problem was refrigerators powered by kerosene (CNN health). Another major issue with vaccination in India was the lack of trust people had in the polio vaccine. Many people believed that the polio vaccine was a government conspiracy that presented adverse side effects, this lead people to refuse polio vaccination (CNN health). Infertility and even death were some of the rumored side effects of the vaccine. Prominent religious figures and government officials played a major role in gaining the trust of the public to try the vaccine (CNN health). This is a great example of how respected individuals/organizations have a huge influence of the opinions of people.The eradication of polio in India required stead fast dedication from all parties involved.

Citations:

http://www.searo.who.int/entity/immunization/topics/polio/eradication/sea-polio-free/en/

http://www.searo.who.int/india/topics/poliomyelitis/surveillance/en/

http://www.cnn.com/2014/03/22/health/india-end-of-polio/index.html?iref=allsearch

http://www.gatesfoundation.org/What-We-Do/Global-Development/Polio

This NYTimes article is relevant to the nature of our discussion on microbiomes and how they can be used for the treatment of various disorders. The article begins by addressing the common misconceptions that fetuses are sterile and that babies are first exposed to bacteria when they exit the birth canal. In 2010, Dr. Josef Neu closely studied stool samples from newborns before their first meal and found diverse microbes in the samples, regardless of whether the child was born on time or prematurely. Additionally, Dr. Esther Quintana studied the amniotic fluid, placenta, and umbilical cord blood of healthy babies and found that each contained a certain amount of bacteria. Questions remain, however, on how the bacteria are first transported from the mother to the fetus and whether a random or beneficial set of microbes are delivered to the fetus during pregnancy. Currently, Dr. Neu and other researchers are studying whether a microbiome helps a fetus during pregnancy. Intriguingly, beyond exploring the microbiome found in fetuses, researchers are also closely studying how the microbiome can be functionalized to treat disorders such as gut infections and autoimmune disorders. For example, the article mentions the possibility of providing a mother with a ‘microbial cocktail’ that can be used to transport specific microbes to the fetus for the treatment of a specific disorder.

I found this article rather interesting as I was not aware that bacteria naturally occur in fetuses, amniotic fluid, and placenta blood. Building from our discussion in class, this article is evolutionarily significant as it suggests that a mother can possibly influence her child’s microbiome, which can ultimately have extensive health and dietary impacts for the child.

http://www.nytimes.com/2013/08/29/science/human-microbiome-may-be-seeded-before-birth.html

Human behavior is closely related to the evolution of sexually transmitted infections, and this paper talks about the impact of the determinants of the STI on disease prevalence and transmission. The paper lists numerous factors that influence infectious disease emergence, including ecological change, human demographics and behavior, international travel and commerce, technology and industry, and microbial adaptation and change. Usually, the combinations of multiple factors that are happening simultaneously affect the transmission of the disease. In addition, the review states that the most direct influence on the evolution of sexually transmitted infections is sexuality and sexual behavior. In order to establish how infectious disease is spread, evaluation of individual sexual behaviors, types of exposure, and the impact of economic, social and structural factor is required. The large variation in age structure in a population has been recognized as crucial factor in the spread of STIs.

Although the determinants of STI prevalence such as urbanization, migration, and poverty were around for a long time, the relatively recent industrialization caused greater economic inequality and changing migration patterns that facilitated the spread of STIs into new populations. The norms may also influence the spread of STIs and size of the population susceptible to STIs. The paper also states that public health and medicine have both positive and negative effects on STI control. Behavioral interventions such as giving sex education, prevention of disease progression, and giving vaccines against HPV strains have been developed to give positive effects. In contrast, the introduction of oral contraceptives and Viagra has increased sexual risk behavior.

In conclusion, the writer emphasizes that human developments affect the spread of sexually transmitted disease agent and its pathogenesis. For example, economic and gender inequality, increased mobility, and global variability of sexual behavior affect the evolution of the agents by changing age structures, unequal gender rates, and globalization.

Citation: Nahmias, S. B. and Nahmias, D. (2011), Society, sex, and STIs: human behavior and the evolution of sexually transmitted diseases and their agents. Annals of the New York Academy of Sciences, 1230: 59–73. doi: 10.1111/j.1749-6632.2011.06079.x

Human movement in terms of spatial and temporal scales is an important factor that affects many vector-borne disease by influencing exposure to vectors and transmission of pathogens. However, very little is known about individual human movement patterns and its effects on the dynamics of vector-borne pathogens. Studying and understanding the human movement and its influences on disease dynamics will enable scientists to come up with a better intervention and disease prevention. The study examines the role and the importance of human movement for pathogen transmission by mostly focusing on mosquito-borne virus. According to the paper, exposure that is due to human movement strongly influences the transmission dynamics of pathogens. For instance, the national or international individual movement drives pathogen introduction and reintroduction.

In order to study the dengue, the ‘activity space’ model was used to determine the few locations individuals visit and spend most of their time. By incorporating the knowledge of vector behavior and the outcome of the activity space model, scientists were able to identify places and individuals that contribute disproportionately to pathogen transmission dynamics. An interesting outcome that the activity space model presented was that the movements of pathogen transmission typically occur mostly at night when hosts are inactive. The paper emphasizes that a better understanding of the role of human movement on pathogen transmission is critical in predicting possible disease outbreak and coming up with better disease preventions schemes.

Citation: Stoddard ST, Morrison AC, Vazquez-Prokopec GM, PAZ Soldan V, KOchel TJ, et al. (2009) The Role of Human Movement in the Transmission of Vector-borne pathogens. PLoS Negl Trop Dis 3(7): e481. doi:10.1371/journal.pntd.0000481

This article talks about Hamiltonian Medicine, which centers on the roles of genetic relatedness in human health and disease and represents the application of basic social-evolution theory, from interactions involving kinship, to core issues in medicine such as pathogens, cancer, optimal growth and mental illness. The 3 domains it incorporates are microbes or cancer cells within humans, genes expressed in humans, and human individuals. I feel that Hamiltonian Medicine is a great way to see and understand how evolution and medicine can work hand-in-hand. I enjoyed how they included that human social interactions, especially among relatives while individuals are young, appear to represent among the most potent and pervasive determinants of mental health throughout the lifespan, both directly and through gene-by-environment interactions. Sometimes I think people assume social interaction and mental health fall strictly under psychology, and I know some people who don’t think there’s any connection between psychology and biology, when this this is not true. Mental health can also be affected by genes and brain function, while social interaction with others has evolved into our society. Humans have not evolved to be solitary creatures. We require interactions with other people to remain healthy. Therefore, the relationships with people who are close to us, especially while young, can have a big impact on our health.

A comical article asks, “Are beards about to die out?” in reference to a recent study examining the frequency-dependent selection of bearded men. According to the article, beards have become very popular lately, but their current popularity will soon make them less attractive.

Though beardedness is a physical trait, it is determined by behavior—shaving or not shaving—rather than solely through genes (frequency-dependent selection is usually studied in organisms like guppies and butterflies with polymorphic color variations). Yet, the same fitness concepts may apply to a behavior if it influences the attraction of potential mates.

This study is unique, because it didn’t simply investigate whether or not people found beards attractive; it measured the attractiveness of beards in multiple frequency contexts. In the experiment, 36 men agreed to grow beards and photographs were taken of them at four intervals of the growth period under identical lighting conditions. The photographs were presented to 1453 women (heterosexual or bisexual) and 213 men (heterosexual). The researchers organized the photographs into multiple contexts ranging from mostly bearded to mostly clean-shaven.

The study found that the attractiveness of beards does fit the model of negative frequency-dependent selection: in the mostly clean-shaven groups, beards were rated about 20% more attractive, but when beards were more common, clean-shaven faces were rated with a similar spike.

This research gives an evolutionary explanation for the cycles of popularity for physical features and clothing. It’s not suggesting that beards will disappear forever due to over-popularity, but it does show that traits are likely to be less attractive when they become too common in a population. This article gave me a new perspective for what it means to be “hipster.”

This article explains the findings of a recently published research that found that Europeans inherited three times as many lipid catabolism genes from Neandertals than Asians did. This is a development that has come out of the extensive comparison of Neandertal and modern human DNA that ensued after researchers at the Max Planck Institute sequenced the Neandertal genome. Researchers have found that Neandertals interbred with modern humans at least once in the past 60,000 years, before their extinction 30,000 years ago. This interbreeding occurred after the decent from Africa; so, traces of Neandertal DNA are not found in Africa DNA, but have been detected in European and Asian DNA—an average of about 1-4%. There is even evidence that different populations of living humans inherited Neandertal genes that may cause diseases like diabetes and Crohn’s, alter immune function, and affect the function of keratin.

According to this research, Northern Europeans have differences in fatty acid composition and in enzymes that metabolize fat in the brain that are traced to Neandertal DNA. Kaitovich and other researchers involved with this study are not sure how these differences affect the brain, but they “think it’s a very strong effect with very profound physiological changes. Otherwise, we wouldn’t see it in the brain tissue.”

Since the fatty acid genes are found in a much higher percentage in Northern Europeans than in Asians, Khaitovich hypothesizes that they were advantageous for modern humans in adapting to colder environments. These findings suggest that one type of human could take an “evolutionary shortcut” by inheriting an advantageous gene from another group, such as the Neandertals, through interbreeding. However, now, these genes are thought to be somewhat disadvantageous for contemporary humans as they are associated with obesity, diabetes, high blood pressure, and cardiovascular disease.

I do not have a background in Anthropology, so I was surprised to learn about the interbreeding of Neandertals and modern humans. Others may be able to provide more insight for the background of this research. I am interested to see what other implications about human health arise from further investigation of these ancient genes.

For my last blog post, I think it’s appropriate to post my idea for my final paper. My paper aims to answer the question, why do humans use contraception if according to strictly evolutionary terms, each individual’s ultimate goal should be to reproduce infinitely? I decided to approach answering the question by first finding examples of natural checks on offspring numbers in other species (which is comparable to our means of artificial control over offspring numbers). Most of the data I encountered was found in birds. One of the most extreme examples off offspring number control was in the Altricial bird. When food is scarce at the time of recently hatched offspring, the siblings compete to get the most food. In this way, a sort of size hierarchy is created as the largest birds are able to outcompete their nest mates. Often, the smallest of the offspring starves to death: a natural check on number of offspring (Godfray et. al.).

A similar check can be found in humans but it is expressed in writing quite differently. It makes sense to say that humans can only have as many children as they can support financially. This is just like how if there are too many offspring in a laying, one of the offspring will most likely starve due to lack of food resources. So, when someone says they use contraceptives to avoid a pregnancy due to financial reasons, although it sounds very different, the comparison to the altricial bird is actually quite similar-it has to do with available resources.

My paper expands upon these ideas, has more examples, more in depth explanation of reasoning to avoid pregnancy in humans, and also the greater evolutionary concept at work. The paper that mentions the Altricial bird is linked below.

http://www.jstor.org/doi/abs/10.2307/2097268

The reading by Nahmias and Nahmias from earlier this month detailed the wide breadth of influencing factors that played a role in the spread of sexually transmitted infections (STIs) throughout human populations all over the world. Although the connection between sexual activity and disease was established a long time ago, the epidemiology behind STIs continues to be ever multi-faceted, making the development and execution of successful interventions very difficult. The paper also explained how the nature of the transmission allows for interesting trends in the evolutionary paths taken by the infectious agents. Many factors were cited as contributing to the spread of STIs, including travel, ecological change, economic inequality and public health issues, among many others, all of which created a complex web of interrelationships in the disease epidemiology.

The article “Love and Sex Influence Disease Evolution” talks about a study from August 2006 in The American Naturalist that examined in detail one of those particular influences on sexually transmitted pathogens. The scientists that authored the study, Eames and Keeling, concluded that the length of time sexual partners stay together has a significant influence on the evolution of multiple strains of a particular infection. It showed that some strains evolve as better suited for monogamous pairings with little chance of a rapid change in host environment (considered slow strains because they have the ability to persist in a host for a long time), while others are better adapted for short term relationship (considered to be fast strains because they cannot utilize resources in order to persist in one host). The study gives further proof for why different strains of a single infection can exist without selecting against each other.

In our recent discussion, we read about the principles of Hamiltonian medicine and discussed its usefulness in addressing human health problems and disease that are occurring worldwide. One of the domains that the paper mentioned and we talked about throughout the class was the microbe-to-microbe social interaction that affects the health of the human host. The “Pathogen-pathogen Interaction” paper was very interesting since I was able to learn about the impacts of the pathogen-pathogen interaction in human disease patterns and review specific examples of disease interactions.

The paper emphasized that infectious agents often do not act independently but cooperate with other pathogens to modify microbial phenotype to persist in the human host. The identified examples of pathogen-pathogen interaction are amoeba/bacteria interaction, HIV/HCV and HIV/fungal interactions, and tick-borne disease interaction. All of these identified case examples are known to impact the health of human populations in recent years.

Several pathogen-pathogen interactions show that pathogens can have significant impact on each other. Based on the pathways the pathogens interact upon one another, pathogens cause different impacts on the host. For example, one disease can promote the contagiousness of another disease by enabling them to penetrate to vulnerable area of the body. Another type of interactions between pathogens can accelerate the virulence of one another. For example, patients who are co-infected with HIV and HSV have a boosting of HIV load along with the higher providing of a portal for entry and exit of the virus.

Since the interactions between pathogens considerably impact the human health, a disease should not be considered as a distinct entity separate from other diseases. Instead, a health professional should pay attention to the syndemics model, which states that aggregation of diseases can have negative health affects, and recognize that interactions among diseases can influence the severity, transmission, and diffusion of the disease within human population.