Soil Transmitted Helminths in Appalachia: an Anthropologic Review

December 2021

Evolutionary Perspective

Soil transmitted helminths [STH] can be spread in three main ways. The first is the fecal oral route which occurs when embryonated eggs are ingested from contaminated soil or feces and larvae migrate through the intestinal tract to the lungs where maturation and dissemination occurs through the bronchial tree. Adult worms then travel to the intestinal tract once again and mature to adulthood. Roundworm and whipworm infections are developed this way. Hookworm, on the other hand, is transmitted through direct skin penetration. When walking barefoot, larvae can enter the skin barrier and travel from blood vessels to the bronchial tree where they are swallowed and develop into adults in the small intestine. Additionally, there is evidence of zoonotic transmission in two documented species of roundworm, A. lumbricoides and A. suum demonstrating evidence of both human and swine infections. Zoonotic transmission can also occur with other mammalian species including horses, racoons, and dogs. The last route of transmission is through inanimate vectors. Contact with contaminated environments such as cutting boards, unwashed produce, or undercooked meats followed by poor hygiene can lead to infections. All methods are related to increased virulence. However, virulence is often linked to evolutionary processes of these parasites. For example, parasitic activity can be characterized by prolonged infection to avoid killing the host. Some parasitic worms live in their host for up to 5 years. They also make use of resources produced by the host to reproduce and transmit infections to new hosts. (Frank, 1996).

Host-Pathogen Arms Race

· Pathogen: found in areas with warm and most climates where poor sanitation and hygiene are poor // Increases reproductive success because the larvae or adult worms will not be killed off and will continue to infect other hosts.

· Pathogen: various routes of infection (skin, fecal/oral, sexual) // Increases reproductive success because worms can easily target a host’s first line of defense which is the skin and other mucosal layers. Do not necessarily rely on a vector to transmit disease.

· Pathogen: infective eggs that mature in soil (roundworm and whipworm) // Increase reproductive success especially in rural areas where there are large areas of soil. Crops may also grow in contaminated soil and improper washing of crops introduces worms to a host.

· Pathogen: zoonotic transmission (roundworm) // Increase reproductive success because it means pathogens have a greater ability to mutate and become more virulent.

· Pathogen: Roundworms produce a lot of eggs, 200,000 per day that live for 10 years in soil; adult worms live in humans for 2 years. Whipworms produce 20,000 eggs, live up to 1 year in humans and multiple years in soil. Toxocara can live in tissues and organs for 5 years // Increase reproductive success because it increases the likelihood that infection will occur. The more larvae that survive, the more successful an infection will be.

· Pathogen: can infect other organs like the pancreas, lungs, liver (roundworm) // May not increase reproductive success because these are vital organs, but roundworm can thrive in a host for several years without killing the host as well.

· Pathogen: do not produce symptoms immediately. Children remain asymptomatic (whipworm and toxocara) // Increases reproductive success because treatment may not be sought out if there are no symptoms present thus allowing the pathogen to keep reproducing.

· Pathogen: difficult to diagnose. Some stool microscopy exams may not detect helminth (strongyloides) // Increases reproductive success because treatment may not start if a physician or healer does not understand what is causing specific symptoms.

· Pathogen: autoinfection which is reinfection with larvae produced by parasitic worms already in the body // Increases reproductive success because the pathogen can continue to cycle through the host without having to die or exit the host and reinfect.

· Pathogens: are macropathogens which prevents breakdown by phagocytic cells // Increases reproductive success because the host cannot effectively stop the infection.

· Host: wash and disinfect fruits and vegetables, proper cooking and peeling fruits and vegetables to remove helminths, proper preparation of meat (toxocara) // Decreases reproductive success of pathogen because it disturbs the methods of transmission commonly used by the pathogen.

· Host: hand washing // Decreases reproductive success by eliminating the pathogen before it can infect the host.

· Host: shoes prevent infections but may lead to infections if not worn // Decreases reproductive success by eliminating the pathogen before it can infect the host.

· Host: diarrhea as a way of clearing viruses, bacteria, or toxins from the digestive tract // Decreases reproductive success by eliminating the pathogen before it can infect the host. However, some parasitic worms are transmitted through fecal oral route. Contact with contaminated feces will increase likelihood of infection.

· Host: revulsion to worms & feces // Decreases reproductive success because it prevents humans from encountering pathogens and contracting a disease.

Host: effector immune responses (innate and adaptive components) // Decrease success of pathogen in some cases. Some parasitic worms avoid the immune system and remain dormant in the body.

Mismatch diseases in Appalachia

Mismatch diseases such as cancer, heart disease, and stroke have been found at higher than national rates in Appalachia and the death rates are also greater in these regions (McGarvey, 2011). In fact, areas with significant rates of stroke mortality known as the “stroke belt” can be found in Appalachian counties. In addition, more than one third of the “diabetes belt” is in central and southern Appalachian counties. The “diabetes belt” is geographically parallel to the “stroke belt” (Crespo, 2020). Changes in the environment and lifestyle are contributors to the increased rates of chronic diseases in Appalachian counties. For example, living in poverty often leads to eating a less varied diet, a reduction in exercise due to a lack of resources and stress, more exposure to pollution, and other factors that are linked to the development of chronic diseases.

Misunderstandings of the Biology of Race: Evolution of Skin Color and Population Genetic Studies

This discussion centers on the disparities in public health and the effect they have on the lives of certain populations. Some Appalachian counties are difficult to reach or are in mountainous areas where proper sewage is absent or lacking, leaving residents to make use of outdoor toilets. Inefficient sewage disposal and fecal management increases the risk of infection and exposes others to contaminated soil. One study found that the highest morbidity rate of stronglyoides infection was among Caucasian men with a compromised immune system (Russell, 2014). A second group that is disproportionately affected are Black persons of low socioeconomic status. This points to the prevalence of racism and discrimination in the healthcare system towards people of color. The last group that is indiscriminately affected by soil transmitted helminths are children. Some common places of infection are playgrounds and sandboxes. There are serious complications that accompany these diseases such as cognitive delays, low school attendance, and limiting higher education (Lynn, 2021).

Ecological Perspective

• First Epidemiological Transition: forced people to settle (not mobile), food procurement changed thus reducing the variety of their diet and immune function (important to defense against infections), herding of animals introduces mutations of viruses and other pathogens and are now able to infect humans, increased fertility = larger families = more people that can be infected with a pathogen & vulnerability to disease

• Second Epidemiological Transition: technological innovations and rapid urban growth created demands for labor, minerals, and timber. Depended on building a transportation system into, out of, and within the region. 1870-1910 - Railroad building era, opened door to full exploitation of region’s natural resources. Coal drove the industrial revolution. 1880-1930 – forestry, timber exploitation, textile mills, non-coal mineral mining, and chemicals production, exposure to harmful chemicals and other environmental pollutants increases chronic degenerative diseases, classism was another issue at this point because poor people were being taken advantage of leading to disparities and prevalence of low socioeconomic status, huge influx of people brought about more diseases which can now be treated with medical and pharmacological inventions

• Third Epidemiological Transition: many made their living from nonfarm work but maintained attachment to the land. 1960s – Appalachian Renaissance filled with strong sense of regional pride, public health initiatives were introduced to rebuild health in these communities, pockets of deep poverty = less access to healthcare and healthy food = increased risk of developing a chronic disease or reoccurring infections, intermingling of animals and humans lead to zoonotic diseases

Ethnomedicine

Explanatory Models of Disease: Social and Naturalistic Etiologies and Treatments

People of Appalachia utilize both folk medicine which are healing practices passed from generation to generation and professional modern medicine. These methods of treatment live in harmony (Boggs, 2018). Folk medicine involves the use of medicinal plants and rituals. One example is moonshine which is a common ingredient in Appalachian folk remedies such as herb tinctures. People living in this region also recognize and respect the role of witch doctors. The respect given to these healers is so extensive that some believe they hold almost as much power as the heavenly Father (Signs, cures, & witchery, n.d.). They are called on to break spells put on by witches. Their skills and knowledge are often passed down from ancestors and their practices are derived from the Bible. Their beliefs include cosmology, supernatural entities, mystical teachings, numerology, and folk spirituality. In the past, women were constantly persecuted and accused of witchcraft. This method of healing is likely not as mainstream as modern medicine, but it is certainly well conserved considering the Appalachian value of family and rigid religious views. The aim of modern medicine is to address the relationship between sanitation and STH through bottom-up sanitation efforts that will eradicate the very organisms responsible for infections (Hawdon, 2014). If a helminth related infection were to occur, there are two possible explanations for the disease. One is the social etiology meaning the root of the illness is linked to the direct actions of an entity. A witch doctor would be consulted in this case. In contrast, a naturalistic explanation would point to an imbalance in the immediate environment such as an animal that the person encountered.

In terms of the social construction of the illness experience, there is a clear regard for the family and the dignity of the individual. Many Appalachian families worship in small, independent congregations that engage in cooperative community service. There is a deep sense of community and belonging to a larger group of people. These people are united by their shared love of the land and place they live in.

Political Economic Approach

Parts of Appalachia have experienced large movements of people and economic ebb and flow. It first began with Europeans expanding their settlements in search of sources of skin for trading. They drove thousands of Native Americans out of the land. Another consideration is the opportunity for pathogens to emerge in this area and lead to diseases. Community members were generally self-sufficient and seldom crossed mountains to seek resources. Additionally, slavery was rare in this area. Larger valleys in Virginia and Tennessee did have need for slave work in salt mines, tanning works, and iron foundries (Appalachia, n.d.). This also had the potential to introduce pathogens to a group. Eventually, technological innovations and rapid urban growth created a demand for labor, minerals, and timber which was abundant in Appalachia. Middle and upper class families moved to Appalachia in hopes of financial opportunities. This usually meant that the native people of Appalachia were going to have their land exploited. Many were forced to transition from farm work to nonfarm work such as railroad building and coal mining. However, none of these industries made a real, lasting impact on the economy of Appalachia. In 1963, the Appalachian Regional Development Act was introduced to fund secondary and vocational education programs, highway construction, and widespread promotion of tourism. This again failed to make an impact on poverty in Appalachia. Those that had the resources could afford to move out and seek more lucrative employment options, but there were others that were left behind to struggle. I believe that there is room for improvement especially in terms of healthcare in these regions. There is a harmful image of people that live in Appalachia that distracts from the real disparities going on in the community. Healthcare providers and other officials should implement programs that meet the needs of these communities on a more personal level. People that live in the mountains are not uneducated or wild, they are humans that are victims of diseases that are preventable if they are allocated the proper resources and education.

References

Appalachia | Encyclopedia.com. (n.d.). Retrieved December 13, 2021, from https://www.encyclopedia.com/places/united-states-and-canada/us-physical-geography/appalachia

Crespo, R. (2020). An emerging model for community health worker–based chronic care management for patients with high health care costs in rural appalachia. Preventing Chronic Disease, 17. https://doi.org/10.5888/pcd17.190316

Frank, S. A. (1996). Models of parasite virulence. The Quarterly Review of Biology, 71(1), 37–78. https://doi.org/10.1086/419267

Hawdon, J. M. (2014). Controlling soil-transmitted helminths: Time to think inside the box? The Journal of Parasitology, 100(2), 166–188. https://www.jstor.org/stable/24624652

Lynn, M. K., Morrissey, J. A., & Conserve, D. F. (2021). Soil-transmitted helminths in the usa: A review of five common parasites and future directions for avenues of enhanced epidemiologic inquiry. Current Tropical Medicine Reports, 1–11. https://doi.org/10.1007/s40475-020-00221-2

McGarvey, E. L., Leon-Verdin, M., Killos, L. F., Guterbock, T., & Cohn, W. F. (2011). Health disparities between appalachian and non-appalachian counties in virginia usa. Journal of Community Health, 36(3), 348–356. https://doi.org/10.1007/s10900-010-9315-9

Prevention, C.-C. for D. C. and. (2021, January 13). Cdc—Soil-transmitted helminths. https://www.cdc.gov/parasites/sth/index.html

Russell, E. S., Gray, E. B., Marshall, R. E., Davis, S., Beaudoin, A., Handali, S., McAuliffe, I., Davis, C., & Woodhall, D. (2014). Prevalence of strongyloides stercoralis antibodies among a rural appalachian population—Kentucky, 2013. The American Journal of Tropical Medicine and Hygiene, 91(5), 1000–1001. https://doi.org/10.4269/ajtmh.14-0310

Boggs, E. L. (2018) :”That mountain is like a drugstore:” Knowledge and Medicine in Southern Appalachia, 1900-1933. [Master’s thesis, Virginia Polytechnic Institute and State University].

Signs, cures, & witchery. (n.d.). Retrieved December 13, 2021, from https://www.youtube.com/watch?v=NwaUcSRsQPQ