Writing Exercise #5 – Consumption and Microbes

Our gut microbial communities are a a reflection of the encounters we, and therefore they, experience. One’s microbiota begins growing during the fetal stage of development and reaches its full potential between ages 2 and 5. However, that is not to say that it indefinitely remains the same. Products such as antibiotics, probiotics, prebiotics, and synbiotics work to alter one’s microbiota by either stimulating growth, introducing new microbes, or killing off others. There are also other choices involving food consumption that may alter our microbiotas as well.

One unintentional choice I sometimes make is skipping meals. Sometimes I get too busy or tired and do not have time to eat. When this happens, not only am I withholding food from myself, but I am also withholding food from my microbes. Our microbes live off the foods we put into our bodies, and if we aren’t eating, neither are they. Lack of a food source could stop colonization. This could be extremely detrimental during stages where microbes are just beginning colonization. If their food source is cut off, they will not be able to reach the exponential growth phase to quickly build their colony.

An intentional choice that affects my microbiota is the foods I eat. As it was mentioned in the lectures, foods such as starches or fermented dishes like yogurt or kimchi are typically good for growing microbiotas. Starches provide a food source for the microbes. This aids in colonization by provision of a food source. Fermented dishes are often fermented by microbes, so consumption of these products directly introduces microbes into the gut. If the microbes used to ferment the foods are different than the microbes within my microbiota, then eating those foods will increase diversity of my microbiota.

Diversity is important since microbes produce natural antibiotics that protect against themselves and in turn, our bodies as a whole. The more species of microbes you have, the more types of resistance to pathogens you can develop. However, if the microbes in the foods are not compatible with the microbes already in our guts, there is a chance they will be viewed as pathogenic by our current microbes. These new microbes will then be expunged.

Writing Exercise #4 – Precis

Reiter, P., Brewer, N., Gottlieb, S., McRee, A.-L., Smith, J. (2009). How much will it hurt? HPV vaccine side effects and influence on completion of the three-dose regimen. Vaccine. 27(49):6840-44.

(1) Paul Reiter, professor at the UNC Gillings School of Global Public Health and researcher at Lineberger Comprehensive Cancer Center, and colleagues in their primary research article titled “How much will it hurt? HPV vaccine side effects and influence of completion on the three-dose regimen” (2009) discuss the side effects of the HPV vaccine and its influence on continuance of the HPV vaccine regimen. (2) Researchers completed a cross-sectional survey, which revealed while pain was frequently experienced, it did not deter patients from receiving successive doses of the vaccine. (3) The purpose of the article was to measure the pain associated with receiving the HPV vaccine to gain a better understanding of the side effects in order to improve acceptance and administration of the vaccine. (4) The article is directed towards public health programs designed to increase awareness on HPV and the importance of receiving the vaccine.

Writing Exercise #3 – Gut Microbes

  1. Prebiotics and probiotics are two popular treatments used to transform the gut microbial community. Prebiotics indirectly increase growth by providing nutrients necessary for the already present microbes to flourish and increase population size. Probiotics directly increase growth by adding microbes themselves to the gut. While the probiotic method is commonly used to treat obesity or ulcerative colitis, it is not through its growth in numbers that healing is achieved, but rather through the effects the microbes have on the gut interactions surrounding them.
  2. Faecal microbial transplantation (FMT) is increasing in popularity for those needing to restructure their gut microbiota. This process restores levels of microbes by transplanting microbes from a healthy subject’s faecal matter into the gut flora of the infected patient. This method has been proven useful for treating several inflammatory diseases
  3. Antibiotics are commonly prescribed for those with an infection. However, antibiotics typically kill all bacteria it comes into contact with, thus disrupting natural levels of gut microbiota. Instead, doctors could transplant antimicrobial-producing microbes into the gut of infected patients. These bacteriocins would be gentler on the gut microbial community since their antimicrobial properties are usually specific to certain types of pathogens. The natural gut flora would not be harmed.

Writing Exercise #2 – HPV Vaccination

There are over 200 strains of HPV. Of those, several have gained attention, as they are considered virulent and related to cervical cancer or genital warts. The high risk strains are 16, 18, 31, 33, 39, 45, 51, 52, 56, 58, 59, and 66, and have been related to the development of cervical cancer. Two low risk strains, 6 and 11, are related to genital warts that are typically noncancerous. While the most commonly received vaccine for HPV is the quadrivalent vaccine Gardisil-4, which vaccinates against four types (16, 18, 6, 11) of HPV, the remainder of high risk strains have yet to be covered. Aside from the four strains covered by Gardisil-4, vaccines should also be made to cover HPV 51 and 53. This suggestion is based on a study done on women with squamous intraepithelial lesions. The study revealed that after the top two most common strains of HPV found, 16 and 31, the next most common strains were 51 and 53, which accounted for 21% of HPV cases. Other strains, such as 31 and 45, do not need their own vaccine since both are closely related to strains 16 and 18 respectively. Thus, the Gardisil-4 vaccine provides cross-protection for those strains though they are not directly targeted.

The best time to administer the vaccines would be early childhood. Studies have shown that development of antibodies against HPV is inversely related to age. One explanation could be that pre-adolescents are still building their immune systems and are more likely to have a stronger reaction to the vaccine. Another explanation is that many older women have already been exposed to HPV, rendering the vaccination ineffective. Since the vaccine is a prophylactic, it is unlikely to benefit those who were already infected by HPV.

Due to high development costs, not all strains of HPV can be covered by vaccination. Including research and manufacturing costs, it costs approximately $200-500 million to develop a new vaccine. Another financial barrier is cost of administration, especially in developing countries. Many facilities are not equipped with pre-adolescent health care services. If new HPV vaccines were developed, it is ideal to focus on the most prevalent, cancer-causing strains. Cervical cancer is responsible for nearly 91% of HPV-related cancer deaths. Protection against more strains would produce a global net benefit that heavily outweighs financial costs. The most benefit would be achieved with high coverage of females, since females directly benefit from the vaccination. Males could also receive the vaccine and add an indirect protection for females, though the net benefit of male vaccination is less than female vaccination.

The topic of HPV vaccinations makes me think about my other class on global health. HPV is a widespread disease that is of high global priority. It is unfortunate that the places most direly need protection do not have the resources to benefit from or even receive that protection.


Cutts, F. T., Franceschi, S., Goldie, S., Castellsague, X., de Sanjose, S., Garnett, G., Edmunds, W. D., Claeys, P., Goldenthal K. L., Harper, D. M., Markowitz, L. (2007). Human pappilomavirus and HPV vaccines: a review. Bulletin of the World Health Organization, 85(9), 649-732.

GM Clifford, RK Rana, S Franceschi, JS Smith, G Gough, JM Pimenta. Human papillomavirus genotype distribution in low-grade cervical lesions: comparison by geographic region and with cervical cancer. Cancer Epidemiol Biomarkers Prev2005; 14: 1157-64.

Smith JF, Brownlow MK, Brown MJ, Esser MT, Ruiz W, Brown DR. Gardasil antibodies cross-neutralize pseudovirion infection of vaccine-related HPV types.23rd International Papillomavirus Conference and Clinical Workshop Abstract PL 1-6, Prague, September 1-7 2006.

Writing Exercise #1 – Non-infectious Diseases

  1. Gastric cancer – Helicobacter pylori
  2. Diabetes – strains of Staphylococcus and other gut microbes
  3. Kidney disease
  4. Heart disease
  5. Alzheimer’s disease
  6. Depression

It is traditionally believed that noncommunicable diseases are not typically caused by microorganisms. Rather, they have been believed to be caused by environmental factors, genetics or viruses. However, increasing studies have recently been conducted trying to find ties between microorganisms and certain non-infectious diseases such as diabetes, cancer, and heart disease, as well as mental conditions such as depression and Alzheimer’s. All the aforementioned conditions have yet to reveal microbial influences, though microbes may have possible causal implications.