Infectious Diseases


Definition

Infectious diseases are illnesses caused by microorganisms which invade and use the resources of an individual to reproduce and spread, directly or indirectly from one person to another to disrupt the normal functioning of the body. Zoonotic diseases are infectious diseases of animals that causes disease when transmitted to humans.[1] Infectious
diseases can be caused by a virus, bacteria, protozoa, fungi, worms or prions. There are various modes of infecting a host; some transmit directly from host to host, while others
use a vector, such as a mosquito which carries malaria and infects a host via bites.[2]

Though the body’s immune system is designed to recognize and protect against infectious diseases, a compromised immune system can allow for infection. Pathogens may enter the body via bites in the skin by drawing blood from an infected host and transmitting the pathogen directly into the bloodstream of another host (ex. Malaria). Other pathogens stick to the skin, are breathed directly into the lungs (ex. Tuberculosis) or are consumed by contaminated food or water (ex. Cholera). Additionally, human to human modes of transmission for infectious diseases include sexual contact or the use of infected medical implements such as syringes (ex. HIV/AIDS and other sexually transmitted infections).[3]

Our bodies have a few mechanisms which attempt to remove pathogens, including coughing to remove them from the respiratory system, an acidic stomach to create a hostile environment, diarrhea to expel the pathogens and fevers which attempt to inhibit bacterial or viral reproduction. Despite these efforts, some pathogens are able to “outsmart” our bodies. Pathogens may hide in cysts that eventually develop scar tissue and become “invisible” to the immune system. Other pathogens will mutate and create new antigens that are not responsive to current treatment. They are also able to change form as a disguise so that the body recognizes the cell as one of its own. Disease pathogens have the ability to reproduce and change rapidly. These changes can increase their ability to transmit to other animals (such as pigs or birds), and they often become even more dangerous to humans following this transition.[4]


History

Many infections common to humanity are the result of derived pathogens from ancestral species. Hence, infectious diseases have become exacerbated by adjustments made to the environment and human lifestyle changes over time.

Prior to about 10,000 years ago, humans subsisted by foraging. Mostly living nomadically, hunter gatherers lived in small groups with low population density. Disease existed within these groups, but never became epidemic or widespread. Chicken pox and herpes simplex infected hunter gatherers. Parasitic infections were contracted from food collection and preparation, in addition to exposure to plants, insects, meat and fish. However, with the domestication of fire and cooking of food, meat-borne pathogens became less prevalent.[5]

It has been said that the transition to agricultural food production was the “worst mistake in the history of the human race.”[6] Once food production became the prominent source of subsistence, lifestyles were transformed. The changes associated with agriculture are numerous and include:

· More concentrated populations
· Populations living in closer proximity
· More sedentary lifestyles
· Less diversified diets[7]

These changes allowed for the proliferation of infectious diseases. Greater population density elevated rates of pathogen transmission because people were living in closer proximity, while increasing contact between other groups and communities. Moreover, humans were faced with the problem of their waste removal. Excess waste increased parasitic transmission. Water and food became contaminated, and without the public health interventions of today, disease proliferated. [8]

The domestication of animals is another reason disease increased with agricultural production. Zoonotic diseases (infections that transfer back and forth between humans and other animals) proliferated based upon closer contact with animals. Some diseases with zoonotic souces that still afflict humans today include tuberculosis, smallpox, influenza, bubonic plague and Chlamydia. Additionally, urban centers facilitating trade were also likely sources contributing to early epidemics of infections.

The effects of European colonization

European colonization also contributed to the spread of disease worldwide. Trade routes and new world conquests devastated indigenous populations, as they were exposed to new pathogens and newly domesticated animals. It is estimated that new virgin soil epidemics (pathogens introduced by Europeans in previously uninfected areas) decimated over “90 percent of the population in Meso-America and the Andes” during the 16th century. Furthermore, sexual transmission of disease grew with colonization.[9]

Colonization in Africa and parts of Asia was not as simple for Europeans as it was in the Americas, because Europeans were subjected to diseases they had no prior exposure to.
In response to becoming infected, European military and government officials living in African and Asian colonies were quarantined to safety in areas away from natives, who were believed to be disease carriers, and thus, “biologically inferior.” European powers justified their colonization by heralding the advancements in scientific medicine they made while
in Africa and Asia, hiding the fact that they were attempting to get rid of these “tropical colonies” which they thought were slowing the “progress” of “civilization.” Soon afterwards,
slave trade and labor in the Americas contributed to the spread of disease as well. The idea of biologically inferior races still persists today, a concept left over from the days of colonialism.[10]

The European contribution to global pathogen exposure created a “global homogenization of disease,” where no border was left uncrossed in the spread of infectious diseases.
The (ill)health effects are long lasting, especially because the health of Europeans improved while the health of colonized nations worsened. Some countries whose health did not improve include those practicing their culture’s “traditional” medical practices (see ethnomedicine), which were not endorsed nor financially supported by Western biomedicine. Following the end of colonization, many countries continued to use and attempted to enhance their “inherited” health care systems which consisted of “inadequate” and “top heavy” structures based on Western medical models. These same models continued to benefit elites and addressed the “rural poor” once the “needs of the urban elite were attended to.” Hospitals in metropolitan areas were first priority, followed by small rural clinics which were underfunded, understaffed and thus, less effective. [11]

The problems persist...

Many countries left with few resources following colonialism have high rates of infectious diseases today, with many placing blame on neoliberal policies. Institutions such as the
World Bank and the International Monetary Fund (IMF) provide loans to countries suffering financially post colonization, in hopes of securing better infrastructure and assisting in national projects. Over time, the debt proved too overwhelming for borrowers, and Structural Adjustment Programs (SAPs) were put into place in order to “liberate public funds for
debt repayment and to improve the conditions for local businesses to export goods to gain foreign currency.”[12]

Upon acceptance of SAPs, countries were required to follow terms set by the IMF. Education and health budgets were “pruned” and suddenly these benefits were seen as “goods
to be paid for by the consumer.” Further, subsidies for “basic foodstuffs (oil, bread, sugar), fuel, public transport, water, sanitation, and medicines were cut or eliminated.” Privatization was encouraged, which led to commoditization of many social services which were previously free or purchased at a nominal cost. Suddenly, people were expected to pay for their medical supplies (“gauze, tape, IV tubes, bed sheets, and hospital food”), medicine, and treatment.[13]

Overall, SAPs have been highly criticized and seen as generally unsuccessful at improving economic situations for countries in need. The poor are unable to purchase basic goods
and services. As prices for foods, transportation and medical care inflated, the health of the poor decreased. Without proper nutrition, immune system effectiveness decreases
making one more susceptible to infectious diseases, especially when compounded with crowded housing situations, unclean water, and poor waste disposal. Once infected, the
poor are disadvantaged, as the health care which was once provided to them at low or no cost, now has a price tag and is accessible only to those who are able to pay.[14]

The health of poverty stricken nations today

The countries reliant upon international aid are those experiencing the most poverty, yet often “receive only small portions of global financial flows.” [15] This creates a cycle of
the poor getting poorer as resources are not funneled in their direction. The recent global economic downturn has diminished support from many countries. According to the 2010 meeting of the Global Fund to fight AIDS, Tuberculosis, and Malaria, they have “failed to raise the $13 billion deemed necessary to keep treating patients at current rates over the
next three years.” [16]

Anthropologists play a role in the world of infectious diseases because they seek to understand and expose the influence of social, cultural, political, and economic factors on the biology of infectious disease. Social inequalities lead to health inequalities, and those burdened by poverty are at a higher risk of becoming infected.

The World Health Organization (WHO) defines health inequalities as:

"...Avoidable inequalities in health between groups of people within countries and between countries. Social and economic conditions and their effects on peoples' lives
determine their risk of illness and the actions taken to prevent them becoming ill or treat illness when it occurs."[17]

Another factor to consider in health discrepancies are what the WHO calls “social determinants of health” which describe a country’s history, “economics, social policies,
and politics.”[18] Anthropologists usually take into consideration race, ethnicity, employment, housing, gender, income and the social factors that bring people into their current situation because these factors often create social stratification and inequalities within a society. Inequities in health are affected by these cultural factors as well as whether or not an individual has access to “power, prestige, and resources.”[19]

Frequently, the overall relative health of a nation is based on life expectancy at birth and infant and child mortality rates. The WHO believes that women faced with high rates of infant and child mortality lead to higher fertility rates. Hence, women are having more children to compensate for more frequent infant deaths. The more children a family must support, the less they are able to “invest in health, education and the future of each child.” [20] Just as seen in the past, increases in population density encourages the spread of infectious diseases, and poor economic situations limit many from receiving needed health care.

The following diagrams are from the World Bank database, demonstrating life expectancy at birth, mortality rates and prevalence of HIV/AIDS. Notice how high rates of HIV/AIDS correlates directly with the other two factors.

Data from World Bank

Data from World Bank

Data from World Bank




People of Interest

Paul Farmer, a medical doctor and anthropologist, is a widely known figure in the world of infectious diseases. Farmer and his colleagues formed Partners in Health (PIH), an organization providing free medical care for tuberculosis and HIV/AIDS in Haiti, Peru, Rwanda, Lesotho, Malawi, Russia, Kazakhstan and the US. In AIDS and Accusation: Haiti and the Geography of Blame, Farmer focuses on understanding why Haiti is struck by such unfortunate health disparities. In the Western Hemisphere, Haiti is the poorest nation and has the highest HIV/AIDS rates. Haiti also has the highest rates of Tuberculosis per capita, undoubtedly exacerbated by poor immunity due to HIV/AIDS.[21] Many cases of tuberculosis in Haiti are known as Multiple Drug Resistant (MDR-TB) and are not susceptible to the free drugs provided by the Haitian government and other national health organizations. Because only a few drugs are able to treat MDR-TB, they are priced higher and have been deemed “cost ineffective” by governments and national aid organizations.[22] Farmer believes this attitude of choosing to only provide “treatment to the affluent," and "no treatment for the poor” is “unacceptable” and is a “double standard of care.”[23]

Farmer is quick to point out that poverty creates a vulnerability to illness. Based on their poverty, people become “socially excluded” and “lack access to effective care.” Thus, social gradients and their compounding factors create what is known as “structural violence.” This phrase, first discussed in the late 1960’s by Johan Galtung, describes the “social structures—economic, political, legal, religious and cultural—that stop individuals, groups, and societies from reaching their full potential.” [24]

Through PIH, Farmer hopes to expose and break through the structural barriers which keep those living in poverty from receiving health care, which Farmer believes is a human right. PIH believes the help they are providing is “a public good” and seeks to deliver care to everyone who seeks it.[25]

Paul Farmer and one of his patients
Paul Farmer and one of his patients








Examples

Malaria

Normally not a problem to North Americans, malaria is the infectious disease most deadly to children worldwide. Said to be one of the world’s oldest diseases, malaria is caused by one of four protozoans within the genus Plasmodium. The blood pulled from the bite of a mosquito carries this disease, over time infecting the host (either human or animal) and residing in red blood cells in order to reproduce. The mosquitoes most likely to carry malaria are called Anopheles mosquitoes. Malaria infects 500 million people per year, killing just fewer than 3 million.[26] These cases are concentrated mainly in sub Saharan Africa, where people are living in poverty and the ecology is well suited for Anopheles mosquitoes.

Mosquitoes thrive in warm environments with pools of standing water. The clearing of land contributes to increased malarial rates. When land is cleared for production, its soil is exposed to direct sunlight, which causes it to harden, and collect water when it rains. These areas of water are breeding grounds for malarial mosquitoes. Malaria remains problematic in the South American Amazon rain forest, where deforestation is creating this situation.

Efforts to control malaria outbreaks were initially effective during the 1950s when the use of the insecticide DDT was shown to significantly decrease mosquito prevalence. Unfortunately, due to short term or incomplete usage, Anopheles mosquitoes built a tolerance to DDT, creating resurgence in malaria only a short time later. The initial success of insecticides changed the WHO focus to controlling malaria instead of its eradication.

Much like with Tuberculosis, malaria treatment drugs have developed resistance over time as well. Cholorquine, the main drug responsible for malaria treatment, is resistant in up to 80% of cases in sub Saharan Africa. This area disproportionately suffers from malaria, accounting for almost 90% of all deaths per year worldwide.

Because malaria was treated and thought to be under control, it is considered a resurgent infectious disease. Many argue global warming contributes to malaria based upon temperature increases resulting in areas where mosquito reproduction thrives. In addition, overpopulation results in greater population density, another contributor to the spread of infectious diseases, such as malaria. Production of new anti-malarial drugs is uncommon, as they are not seen as a profitable business venture by pharmaceutical companies as malaria predominantly affects those living in poverty.

Infection from the malaria parasite can result in a number of symptoms, ranging from very mild to very severe, including death. The incubation period of most malaria cases can
range anywhere from 7 to 30 days. Malaria is the second leading cause of death in Africa, after HIV/AIDS and is the fifth cause of death from infectious diseases worldwide
(after respiratory infections, HIV/AIDS, diarrheal diseases, and tuberculosis).[27]

CDC map. Concentrations of malaria transmission worldwide.
CDC map. Concentrations of malaria transmission worldwide.


















HIV/AIDS

Few can deny the notoriety of HIV/AIDS as an infectious disease. As of 2009, the Joint United Nations Programme on AIDS (UNAIDS) estimated 33.3 million people were living
with HIV/AIDS worldwide; 67% of these infections are concentrated in sub Saharan Africa. Of the 33.3 million people infected worldwide, 30.8 million are adults, 15.9 million
are women, and 2.5 million are children. Approximately 2.6 million people were newly infected with HIV in 2009.[28] In the United States, it is estimated that more than one
million people are living with HIV, in which the HIV/AIDS epidemic has disproportionate effects on the Black community. [29]

HIV/AIDS was introduced as an infectious disease during the 20th century. The first cases were diagnosed in the United States in the early 1980s. This misunderstood illness was originally thought to only exist among four risk groups, better known as the 4Hs: Homosexuals, Haitians, Hemophiliacs and Heroin users. However, as HIV/AIDS has become pandemic, it is better understood and is known not just to be isoloated to certain groups of people. There are various modes of HIV transmission which include: male to male sexual contact, injection drug use, and heterosexual contact. In some developing countries where antiretroviral drugs are not affordable or readily accessible, mother-to-child transmission still poses a possible risk of infection.

Epidemiologist Elizabeth Pisani is well known for her research on HIV/AIDS. To say the least, she feels strongly about HIV/AIDS prevention tactics, describing outcomes as a “giant, in-your-face failure.” International agencies providing assistance are quick to blame “poverty and underdevelopment,” for the high concentrations of HIV/AIDS in Africa. However,
Pisani believes these agencies are dancing around the topic of sex, which she insists must be openly discussed as it relates to HIV/AIDS and its rampant spread throughout Africa.

Pisani argues that poverty alone cannot cause such high rates of HIV/AIDS. Many countries have people who experience poverty, yet they have low incidences of the infection. Multiple partners comes as a result of women who are forced into sex work as a means of income and men who migrate for work (and consequently spending more time away from home).
It is believed that Africans having multiple sexual partners coupled with low condom usage is what allows for such rampant spread of HIV in sub Saharan Africa. Also, many young
women are drawn to the benefits of dating older men (ex. cash, car and cell phone), which heightens power differentials between men and women. Women seeking payment from
sex and others in vulnerable positions do not feel they can demand a man wear a condom. After all, it is the men with the money, and if they do not wish to wear a condom, they
will find a woman who will have sex without one.[30]

Pisani uses Swaziland as an example of HIV prevention failures. Swaziland has the highest rates of HIV/AIDS in the world, with an estimated 26.1% of persons aged 15-49 being infected. Unfortunately, their king does not set a positive example for reducing the number of sex partners to reduce HIV, as he has 13 wives, the newest one being younger than
his eldest daughter.[31]

Conversely, addressing sex head on has proven successful in Senegal and Uganda, where they have “dropped the ‘our people don’t sleep around’ hypocrisy” and stressed the necessity of lessening the number of sexual partners. Their presidents were not afraid to talk about young women having sex with older men and encouraged people to stop
“roaming around” by implementing a “zero grazing” campaign. [32] These strategies were supplemented with “massive distribution” of condoms. Currently, Senegal and Uganda
have HIV/AIDS prevalence rates of 1% and 5.4% respectively. Prevalence in Uganda has decreased from 15% in 1991.[33]

The following video is an example of how women in Zimbabwe are using a regular social occurrence like getting braids as a means of educating themselves as well as educating
others about ways to protect themselves from HIV transmission.











































Subject Author Replies Views Last Message
No Comments



Resources




Bibliography


  1. ^ World Health Organization
    Health Topics, Infectious Diseases
    http://www.who.int/topics/infectious_diseases/en/
    accessed March 11, 2011.
  2. ^ Wiley, Andrea S., and John S. Allen
    2009 Medical Anthropology: A Biocultural Approach. New York: Oxford University Press.
  3. ^ Wiley, Andrea S., and John S. Allen
    2009 Medical Anthropology: A Biocultural Approach. New York: Oxford University Press.
  4. ^ Wiley, Andrea S., and John S. Allen
    2009 Medical Anthropology: A Biocultural Approach. New York: Oxford University Press.
  5. ^ Barrett, Ronald with Christopher W. Kuzawa, Thomas McDade and George J. Armelagos
    1998 Emerging and Re-emerging Infectious Diseases: The Third Epidemiologic Transition. Annual Review of Anthropology 27:247-271.
  6. ^ Wiley, Andrea S., and John S. Allen
    2009 Medical Anthropology: A Biocultural Approach. New York: Oxford University Press.
  7. ^ Wiley, Andrea S., and John S. Allen
    2009 Medical Anthropology: A Biocultural Approach. New York: Oxford University Press.
  8. ^ Barrett, Ronald with Christopher W. Kuzawa, Thomas McDade and George J. Armelagos
    1998 Emerging and Re-emerging Infectious Diseases: The Third Epidemiologic Transition. Annual Review of Anthropology 27:247-271.
  9. ^ Barrett, Ronald with Christopher W. Kuzawa, Thomas McDade and George J. Armelagos
    1998 Emerging and Re-emerging Infectious Diseases: The Third Epidemiologic Transition. Annual Review of Anthropology 27:247-271.
  10. ^ Barrett, Ronald with Christopher W. Kuzawa, Thomas McDade and George J. Armelagos
    1998 Emerging and Re-emerging Infectious Diseases: The Third Epidemiologic Transition. Annual Review of Anthropology 27:247-271.
  11. ^ Gish, Oscar
    2004 The Legacy of Colonial Medicine. In Sickness and wealth: the corporate assault on global health. Meredith Fort,
    Mary Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  12. ^ Steve, Gloyd
    2004 Sapping the Poor: The Impact of Structural Adjustment Programs. In Sickness and wealth: the corporate assault on global health. Meredith Fort, Mary Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  13. ^ Steve, Gloyd
    2004 Sapping the Poor: The Impact of Structural Adjustment Programs. In Sickness and wealth: the corporate assault on global health. Meredith Fort, Mary Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  14. ^ Steve, Gloyd
    2004 Sapping the Poor: The Impact of Structural Adjustment Programs. In Sickness and wealth: the corporate assault on global health. Meredith Fort, Mary Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  15. ^ Steve, Gloyd
    2004 Sapping the Poor: The Impact of Structural Adjustment Programs. In Sickness and wealth: the corporate assault on global health. Meredith Fort, Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  16. ^ National Public Radio
    2010 AIDS Fight Sees Decline in Global Support. National Public Radio. http://www.npr.org/templates/story/story.php?storyId=130377718, accessed October 7, 2010.
  17. ^ World Health Organization
    N.d. Key Concepts. World Health Organization.
    http://www.who.int/social_determinants/final_report/key_concepts_en.pdf,
    accessed September 23, 2010.
  18. ^ World Health Organization
    N.d. Key Concepts. World Health Organization.
    http://www.who.int/social_determinants/final_report/key_concepts_en.pdf,
    accessed September 23, 2010.
  19. ^ Marmot, Michael
    2007 Achieving health equity: from root causes to fair outcomes. The Lancet 370:
    1153-1163.
  20. ^ World Health Organization
    N.d. Key facts and findings on the linkages of health and development.
    World Health Organization. http://www.who.int/macrohealth/background/findings/en/index.html,
    accessed October 6, 2010.
  21. ^ USAID
    2009 Haiti Tuberculosis Profile. USAID from the American People. http://www.usaid.gov/our_work/global_health/id/tuberculosis/countries/lac/haiti.pdf, accessed October 24, 2010.
  22. ^ Farmer, Paul
    1999 Infections and Inequalities. Berkeley: University of California Press.
  23. ^ Farmer, Paul
    1999 Infections and Inequalities. Berkeley: University of California Press.
  24. ^ Farmer, Paul, with Bruce Nizeye, Sara Stulac and Salmaan Keshavjee
    2006 Structural Violence and Clinical Medicine. Public Library of Science
    Medicine 3(10):e449.
  25. ^ Partners in Health
    N.d. What We Do: The PIH Model of Care--Partnering with Poor Communities to Combat Disease and Poverty. http://www.pih.org/pages/what-we-do/,
    accessed September 14, 2010.
  26. ^ Holtz, Timothy and S. Patrick Kachur
    2005 The Reglobalization of Malaria. In Sickness and wealth: the corporate assault on global health. Meredith Fort,
    Mary Anne Mercer, and Oscar Gish, eds. Pp. 43-54. Cambridge: South End Press.
  27. ^ Centers for Disease Control and Prevention. Malaria
    http://www.cdc.gov/malaria/about/disease.html, accessed March 11, 2011.
  28. ^ UNAIDS 2010. UNAIDS Report on Global AIDS Epidemic.
    http://www.unaids.org/globalreport/Global_report.htm, accessed March 11, 2011.
  29. ^ Centers for Disease Control and Prevention (2010). HIV/AIDS in the United States [Fact Sheet].
    http://www.cdc.gov/hiv/resources/factsheets/PDF/us.pdf, accessed March 11, 2011.
  30. ^ Pisani, Elizabeth
    2008 The Naked Truth. In The Wisdom of Whores. Pp. 124-160. New York: W.W.
    Norton.
  31. ^ Pisani, Elizabeth
    2008 The Naked Truth. In The Wisdom of Whores. Pp. 124-160. New York: W.W.
    Norton.
  32. ^ Pisani, Elizabeth
    2008 The Naked Truth. In The Wisdom of Whores. Pp. 124-160. New York: W.W.
    Norton.
  33. ^ CIA The World Factbook
    2010 The World Factbook. https://www.cia.gov/library/publications/the-world-factbook/, accessed October 9, 2010.