biohazards: disease and invasive species

epidemiology

The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control health problems

endemic

A disease that is constantly present at low or high levels within a specific population or geographic area

→ For example, cholera is endemic to the Ganges region, and Dengue fever is now endemic in over 100 countries

epidemic

A condition where the incidence of an infectious disease is much greater than expected under usual conditions in a specific population

pandemic

An epidemic that has spread over a very large area, typically crossing international boundaries and affecting several countries or continents

→ ex: HIV/AIDS and the 1918–1919 influenza

zoonoses

Diseases for which non-human species are the natural reservoir for the infectious agents, which then "jump" to humans → happens naturally

anthroponoses

Diseases that have adapted through evolution to have the human species as their primary or exclusive host

→ spread through human to human transmission; human to animal is reverse anthroponoses

infectioius

Also known as communicable diseases, these are diseases that you can "catch" from another person or through non-human vectors

four main modes of transmission for diseases. provide examples

1. anthroponoses (direct transmission) = In this mode, the disease moves directly from human to human without an intermediate vector or vehicle → ex: HIV/AIDS (via sexual contact or shared needles), Measles (via airborne droplets), and Tuberculosis (airborne)

2. anthroponoses (indirect transmission) = This involves the movement of a human-specific disease from human to human via an intermediate vector (like an insect) or a vehicle (like water or food) → Examples: Malaria (transmitted between humans by mosquitoes), Cholera (transmitted through contaminated water or food), and Dengue fever (transmitted by mosquitoes)

3. zoonoses (direct transmission) = These diseases are transferred directly from an animal host to a human → Examples: Rabies (typically through an animal bite) and Ebola (through close contact with infected animal materials or body fluids)

4. zoonoses (indirect transmission) = These diseases originate in an animal reservoir but are transmitted to humans through an intermediate vector or vehicle → Examples: Bubonic plague (rats to humans via fleas), Lyme disease (deer/rodents to humans via ticks), and West Nile Virus (birds to humans via mosquitoes)

what four factors shape our exposure and vulnerability to disease?

1. The pathogen must be virulent, meaning it has the capacity to cause illness or death.

2. An individual must come into contact with the pathogen or its vector (exposure).

3. The pathogen must be able to evade the human body's immune system.

4. The pathogen must circumvent societal measures designed to prevent its harm

→ While natural characteristics like the type of pathogen determine the nature of a bio-hazard, human vulnerability is largely a result of the cultural, political, and economic systems we have established

how does this information (knowing the factors that shape vulnerability to diseaso) help us in thinking through how we prepare, mitigate, and respond to this type of hazard. (4 points)

• Targeting Contact/Exposure: Mitigation strategies often focus on breaking the chain of transmission. For waterborne diseases like cholera, this involves providing clean water and improved sanitation to prevent contact with contaminated sources. For vector-borne diseases like malaria, it means using treated nets and managing stagnant water to reduce contact with mosquitoes.

• Strengthening the Immune System: Preparation includes vaccination programs, which create herd immunity and prevent the spread of highly contagious diseases like measles. Additionally, addressing poverty and poor nutrition is vital because a weakened immune system increases vulnerability.

• Improving Societal Measures: Effective response requires coordinated public policy and education to counter misinformation. For example, in South Africa, addressing gender-based violence is recognized as a necessary societal measure to mitigate the spread of HIV.

• Addressing Virulence and Resistance: Responding to the threat of "superbugs" and drug-resistant diseases like MRSA or MDRTB requires rapid surveillance, isolation of infected individuals, and improved pharmaceutical research

what is a DALY and why is this used to measure the burden of a disease?

DALY (Disability Adjusted Life Year) = a measure of the overall burden of a disease, expressed as the cumulative number of years lost due to ill-health, disability, or early death. It is calculated using the following formula: DALY = YLD (Years Lived with Disability) + YLL (Years of Life Lost)
→ This measurement is used to measure the burden of a disease because it provides a more comprehensive picture than mortality rates alone. By including morbidity (the impact of living with a disease or disability), the DALY captures the long-term economic and social impacts of illnesses that may not be immediately fatal but significantly diminish quality of life and productivity.

We briefly looked at global trends in outbreaks over a 30 year period ending in 2010. Be able to identify the general trend (actual numbers not needed) with regards to 1) number of outbreaks, 2) disease richness (ie diversity of diseases), 3) disease type (viruse, bacteria etc…), and 4) vectorborne versus non-vectorborne

Between 1980 and 2010, the world saw a significant upward trend in the scale and variety of infectious disease events. These trends can be broken down as follows:

Global Trends in Outbreaks (1980–2010)

• Number of Outbreaks: There has been a clear global rise in the total number of human infectious disease outbreaks over this 30-year period.

• Disease Richness: The diversity of diseases—referred to as disease richness—has also increased, meaning more unique types of infectious agents are causing outbreaks than in previous decades.

• Disease Type: While outbreaks have increased across all taxonomies (including fungi, parasites, and protozoans), bacteria (48%) and viruses (40%) are the primary drivers of global outbreaks. The largest "killers" typically include all three major types: bacteria, viruses, and protozoa.

• Vectorborne vs. Non-Vectorborne: Although both categories have seen an increase in activity, non-vectorborne diseases account for the vast majority—roughly 87%—of all recorded outbreaks

Describe in some detail how poverty/wealth influences vulnerability to infectious disease. Refer to the four factors shaping exposure and vulnerability

The sources highlight a massive global inequality in disease impact: 98% of deaths from communicable diseases occur in impoverished "periphery" nations. In these regions, infectious disease causes 42% of all deaths, compared to only 1.2% in wealthy "core" nations. This disparity is explained through the four factors of vulnerability:

1. Contact with the Pathogen or Vector (Exposure) Poverty often forces individuals into crowded living conditions, urban slums, or refugee camps, which creates "breeding grounds" for rapid transmission. Impoverished areas frequently lack clean water and effective sanitation, significantly increasing exposure to waterborne diseases like cholera and parasites like schistosomiasis.

2. The Virulence of the Pathogen While the biological nature of a pathogen is a "natural" hazard, human systems influence its deadliness. In poor regions, the inability to complete full courses of medication or the misuse of antibiotics leads to the evolution of "superbugs" and drug-resistant strains, such as multi-drug-resistant tuberculosis (MDRTB), which are much more difficult to treat.

3. Evading the Immune System Vulnerability is high among the poor because poor nutrition and high levels of stress or trauma weaken the body's natural immune response. Without a robust immune system, pathogens that might cause minor illness in a wealthy, well-nourished person can become lethal.

4. Circumventing Societal Measures This is where wealth provides the greatest protection. Wealthy nations have robust public health infrastructure, high vaccination rates, and advanced surveillance systems. In contrast, poverty leads to institutional failure, lack of resources, and market failure. Pharmaceutical research and development is overwhelmingly directed toward the "lifestyle" problems of the wealthiest 10% (such as hair growth or cholesterol) rather than the infectious diseases that kill millions in the periphery (such as malaria), because there is little profit in finding cures for the poor.

How does the above reflect on where we find high levels of mortality associated with infectious diseases?

The distribution of mortality associated with infectious diseases is starkly unequal, reflecting a massive global divide between wealthy "core" nations and impoverished "periphery" nations.

• Concentration of Death: Approximately 98% of deaths from communicable diseases occur in the periphery. Infectious disease accounts for 42% of all deaths in these poor nations, compared to only 1.2% in core countries.

• Leading Killers: In low-income countries, the top causes of death are dominated by infectious agents, including lower respiratory infections, diarrheal diseases, HIV/AIDS, tuberculosis, and malaria. In contrast, high-income nations primarily face mortality from chronic conditions like heart disease and cancer.

• Market and Institutional Failure: This disparity is driven by a "market failure" in the pharmaceutical industry. Of 1,233 new medicines patented between 1975 and 1997, only 13 were for tropical diseases. Research and development are overwhelmingly directed toward "lifestyle" problems of the wealthiest 10% to 20% (e.g., hair growth, cholesterol, and depression) rather than diseases like malaria that kill millions in the periphery, because there is little profit in finding cures for the poor.

What is the relationship between processes of globalization and the emergence or re-emergence of infectious diseases? Provide examples

Globalization facilitates what experts call "microbial traffic"—the movement of pathogens across the globe via trade, travel, and migration. The unprecedented speed and distance of modern transportation mean that a disease contracted on one continent can be transmitted to a new population the very next day.

Examples of Globalization-Driven Transmission:

• SARS (2003): Originally emerging in China, the virus spread to 37 countries within weeks due to the international airline network.

• Cholera: The recent reintroduction of cholera to the Americas was traced to a freighter from Asia dumping its contaminated bilge water into the ocean off the coast of Peru.

• "Airport Malaria": Cases have been documented where individuals living near international airports (such as Geneva or Newark) contracted malaria despite never travelling to endemic areas; this occurs when infected mosquitoes survive in the wheel wells of aircraft and fly out upon landing.

• International Food Supply: An outbreak of Cyclospora in the U.S. was linked to the importation of raspberries from Guatemala, illustrating how the globalization of food sources can introduce rare pathogens into temperate climates.

Different societal environments can facilitate the spread of different diseases. Why are refugee camps often breeding grounds for epidemics? How about prisons?

Certain environments create ideal conditions for the rapid spread of disease because they strip away the societal measures and biological protections that usually mitigate hazards.

Refugee Camps: These are often breeding grounds for epidemics because they combine several high-risk factors:

• Disruption of Services: Livelihoods and standard health services are typically non-existent or severely disrupted.

• Infrastructure Failure: There is often a critical lack of clean drinking water and effective sanitation.

• Crowding and Nutrition: High population density facilitates rapid transmission, while food shortages and the trauma of displacement weaken the residents' immune systems.

Prisons: Prisons are identified as specific breeding grounds for diseases such as HIV/AIDS and Hepatitis C. The combination of crowded living conditions and a lack of access to preventative measures or adequate healthcare makes these populations highly vulnerable. Similar to urban slums, these environments allow pathogens to circumvent the societal measures designed to prevent harm

in the article Brown, Loch T. & C. Eberdt (2007) "The Endemic Epidemic: New Challenges in the Battle Against HIV/AIDS in South Africa" in MUMJ, Vol. 4, No. 1., argues that the spread of HIV/AIDS and gender based violence are co-epidemics, what do the authors mean by this and why do they argue they should be seen as co-epidemics?

In the article by Brown and Eberdt (2007), the authors argue that HIV/AIDS and gender-based violence (GBV) are co-epidemics because they are mutually reinforcing social and health crises that cannot be effectively managed in isolation.

The Argument for Co-Epidemics

The authors define them as co-epidemics because of the deep interrelationship between the two:

• Direct Vehicle of Transmission: Rape is cited as one of the leading vehicles for HIV transmission in South Africa.

• Increased Biological Risk: The physical trauma associated with forced sex significantly increases the risk of HIV transmission to women during the act.

• Power Dynamics and Prevention: Even in consensual sexual relations, women suffering from abuse often lack the social power to negotiate the use of a condom.

• Indirect Vulnerability: GBV leads to a host of chronic physical and mental health issues—including depression, substance abuse, and other STDs—all of which indirectly increase a woman’s risk of contracting HIV.

• Systemic Normalization: The authors point to the normalization of violence within marriage and the staggering statistics (such as one woman being raped every 26 seconds in South Africa) to argue that the spread of HIV is not just a medical issue, but a social one rooted in gender inequality

What are the core traits of an invasive species (we looked at 5)

Invasive species (also known as non-native, alien, or introduced species) are organisms that disrupt the environments they invade. The sources identify five core traits that allow these species to become successful and often disastrous invaders:

1. Reproductive Advantages: They often exhibit rapid reproduction rates, allowing them to establish large populations quickly.

2. Growth Advantages: They possess faster or more vigorous growth than native species, often seizing sunlight and nutrients from competitors.

3. Environmental Durability and Flexibility: They have high ecological, diet, and phenotypic plasticity, meaning they can thrive under a wide range of climatic and habitat conditions.

4. Spread or Dispersal Advantages: They are highly efficient at dispersing offspring over large distances, often through wind, water, or animal vectors.

5. Association with Human Activity: Successful invasions are frequently tied to human-mediated movement (accidental stowaways or intentional introduction) and thrive in landscapes already disturbed or degraded by human impact

We discussed that challenges of defining what entails an invasive species. How do you define an “invasive species”?

An invasive species (also referred to as non-native, alien, exotic, or introduced) is any plant, animal, or micro-organism that disrupts or adversely affects the environments, habitats, or bioregions it enters. While the term "non-native" simply refers to a species originating elsewhere, "invasive" specifically denotes species that cause economic, environmental, or ecological damage. Invasive species are considered the second greatest cause of biodiversity loss globally, trailing only habitat destruction.

In his article *Robbins, Paul (2004) “Comparing Invasive Networks: Cultural and Political Biographies of Invasive Species”, Geographical Review, 94 (2) , Robbins suggests that “It is not species but sociobiological networks that are invasive.” Explain what Robbins means by this. An excellent answer would reference actor network theory (answer what actor network theory is in another card)

This perspective shifts the focus away from the inherent biological traits of a plant or animal and toward the complex human and non-human systems that facilitate its spread..

What Robbins Means by "Invasive Networks"

Robbins argues that species expansion occurs because specific power-laden networks create the necessary momentum.

1. Preparation of the Landscape: Invasion often requires "social preparation," such as changes in land-use practices (e.g., the modernization of livestock management allowed kudzu to spread in the U.S. South).

2. Institutional Alliances: Successful invaders often form "alliances" with human institutions. For example, Mexican mesquite (Prosopis juliflora) became a global weed because it was supported by state forestry bureaucracies that wanted to meet "green" land-cover targets quickly.

3. Socioeconomic Marginalization: Invasions are frequently linked to the marginalization of people. In the Yucatan, the spread of bracken fern is tied to land scarcity and high labor costs, which prevent poorer farmers from controlling the weed.

Ultimately, Robbins argues that we cannot understand invasion by looking at the species in isolation; we must examine the network of allied species, land managers, and bureaucracies that allow it to thrive

Can native species be invasive?

Yes. The sources clarify that indigenous species can behave in an invasive way when local ecological structures or environmental conditions become unstable or imbalanced. For example, the Mountain Pine Beetle is native to western North America, but due to climate change (warmer winters) and human logging practices (creating uninterrupted stands of trees), its population has exploded, leading to the devastation of hundreds of thousands of square miles of forest

Are crops invasive species?

The majority of domesticated crops, flowers, and animals raised today are non-native species; in the United States, 98% of the food supply comes from introduced species. However, most crops are not considered "invasive" because they rely on humans to survive and do not typically outcompete local species to cause ecological harm. A species is only "invasive" if it possesses traits like rapid reproduction and environmental durability that allow it to seize an ecosystem niche and cause unintended consequences

What about humans, do we count as invasive species?

The sources suggest that humans can be viewed as the most destructive invasive species. Human activity—both accidental and intentional—is the primary vector for species invasions, and our direct impact on biodiversity is staggering. For instance, human-built environments like skyscrapers and glass windows kill an estimated one billion birds in North America annually

what is actor-network theory and how does robbins’ utilizes it

The Role of Actor-Network Theory (ANT)

Robbins utilizes Actor-Network Theory to explain that "invasion" is not a random biophysical accident, but a co-produced event. Key concepts from ANT include:

• Emergent Agency: In this model, agency (the power to act or change an environment) does not belong to a single organism. Instead, it is an emergent property of the network. The capacity for a species to invade is only "imbued by its position in a network of heterogeneous elements," such as bureaucrats, soil conditions, landowners, and the species itself.

• Mutual Constitution: Drawing on thinkers like Donna Haraway, Robbins suggests that actors—including trees, missionaries, and farmers—do not pre-exist their relationships but constitute each other through their interactions. An invasion is a dramatic example of this mutual constitution.

• Power in Relationships: Power in a network model "lies not in the properties of actors but in the relationship established between them"