Adaptation to Biological Stressors Part 2: Infectious Disease PDF

Adaptation to biological stressors part 2: Infectious disease AANT 211: Human Population Biology  Introduction Malnutrition Infectious diseases 1. Humans, disease, and adaptations 2. Epidemiological Transition 3. History of disease 4. Modern Cities, Disease, and C...

Adaptation to biological stressors part 2: Infectious disease AANT 211: Human Population Biology  Introduction Malnutrition Infectious diseases 1. Humans, disease, and adaptations 2. Epidemiological Transition 3. History of disease 4. Modern Cities, Disease, and Culture 2  1. Humans and Disease Co-evolving for thousands of years Have we adapted? yes no somewhat 3 Infectious Diseases Vector-borne diseases Malaria Direct-contact diseases Ebola Intimate contact diseases HIV Poor sanitation diseases Cholera 4  Malaria Vector-borne infectious disease Plasmodium falciparium Anopheles mosquitoes Plasmodium reproductive cycles in both human and mosquito 5  Malaria Adaptations Hb variants HbS: Sickle cell trait Thalassemia G6PD deficiency 6  Ebola Virus Disease (EVD) Direct-contact/Zoonosis – Transmitted to humans from animals – Highly virulent in humans Pathogen's or microbe's ability to infect or damage a host Fruit bats are natural hosts – Close contact w/blood, secretions, organs or other bodily fluids of infected animals Monkeys and apes – Then spreads through human-to-human transmission via direct contact 7 8  Ebola Virus Disease (EVD) Symptoms – Fever fatigue, muscle pain, headache, sore throat – Vomiting, diarrhea, rash, symptoms of impaired kidney and liver function – In some cases, both internal/external bleeding Transmitted via contact with bodily secretions – 50% fatality rate (25-90% range) – 1st outbreak in C. Africa (1976) 318 cases - 218 deaths – Largest outbreak in W. Africa (2014-2016) ~29,000 cases - ~11,500 deaths – More recent outbreak in DRC (2018-2020) ~3,000 cases - ~2,000 deaths 9 EVD: Treatment and Adaptations Rehydration with oral/IV fluids Monoclonal antibody treatments Bind to proteins on virus surface like natural antibodies would RCT during 2018-2020 outbreak in DRC Vaccine One approved, only effective against one of the viruses that cause EVD Population-specific adaptations? What do you think?  HIV Intimate-contact disease Human Immunodeficiency Virus Weakens immune system Destroys immune cells CD4 cells (T cells) Harder to fight infections and cancer West Africa Simian Immunodeficiency Virus (SIV) mutated into HIV Chimpanzee Sooty mangabey (African monkey) late 1800s? Existed in U.S. since mid to late 1970’s 11  HIV Adaptations Varying degrees of resistance – Live w/infection for 20 years; some die w/in a year Chemokine receptor 5 (CCR5) – Allows chemical signals to enter cell – Used by HIV to bind to T cells – CCR5-Δ32 variant (mutation) Lack receptors – Homozygous carriers resistant to certain strains of HIV-1 12  HIV Adaptations Chemokine receptor 5 (CCR5) – CCR5-Δ32 variant (mutation) Lack receptors 13 HIV Adaptations Previous selection for resistance to a different disease? 15 HIV treatment Anti-retroviral therapy (ART) Can reduce viral load to undetectable If undetectable, prevents/reduces transmission Pre-exposure Prophylaxis (PrEP) Reduces risk of infection Post-exposure Prophylaxis (PEP) Taken within 72 hours of exposure  Cholera Poor sanitation Vibrio cholerae Water-borne Feces in water Symptoms Dehydration Diarrhea/Vomiting 2.9 million cases a year 95,000 deaths Mild to severe 10% have severe symptoms Can die in hours 17  Cholera Adaptations Variation in susceptibility Type O more susceptible Lack of A or B antigens? Hyperactivates a key signaling molecule in intestinal cells Leads to inflammation Excretion of electrolytes and water Type O Blood Cholera Cases 18 Malnutrition & Infectious Disease 19  2. Epidemiological Transition Explains shifts in human disease patterns over the past 10kya Abdel Omran (1971) – How patterns of mortality change over time Disease burden – Infectious (communicable) to chronic (non-communicable) – Ongoing in low and middle income countries today 20 21 Epidemiological Transition – Now/Future 1. Age of pestilence & famine Emergence of infectious and nutritional diseases 2. Age of receding pandemics Industrial Revolution 3. Age of chronic & man-made diseases “Degenerative disease” Late 20th c. 4. “Novel” diseases Reemergence of infectious disease – Increasing microbial resistance (antibiotic resistance) – Increasing zoonotic diseases » Microbes move from animal host to infect humans » E.g. COVID-19, SARS, HIV, Ebola Globalization – Rapid spread 22 3. Diseases of the Past Hunting-gathering/foraging prior to 10kya ~10kya (Neolithic/early agriculture) Preindustrial cities 23  Diseases of the Past Hunting-gathering/foraging prior to 10kya – Small population size and density – Temporary settlements/without shelter or with simple dwellings – Diseases of exposure Parasites - lice, worms, intestinal protozoa Zoonoses (e.g., yellow fever) 24  Diseases of the Past ~10kya (Neolithic) Agriculture increase in population size/density increase fertility sanitation issues Permanent settlements changed landscape create new environment for diseases irrigation ditches clearing land 25 Diseases of the Past Communicable diseases Originated from animal viruses Measles, rubella, mumps, chicken pox, smallpox Sweep through every few years Children not previously exposed during prior epidemics get infected 26 Diseases of the Past Emergence of cities (~3000 BCE) – Very high population density – Storing a lot of food and water – Large amount of sewage Contaminated food and water – Typhoid fever Salmonella typhi – Cholera Vibrio cholerae First pandemic in Ganges Delta 27 What did we know about disease? Miasma theory Poisonous vapor Suspended particles of decaying matter Middle ages to the late 19th c Rapid industrialization/urbanization Concentration of waste Remove bad smells = actually removing germs and bacteria 28 Understanding of Disease Germ Theory of Disease Emerged in 2nd half of 18th c Microorganisms (pathogens) can cause infectious diseases We already knew about germs Made no connection with disease Louis Pasteur Germ (infectious agent) Replaced miasma theory 29 Preindustrial Cities social stratification led to disparities in risk of illness and death access to nutrition and medical care risks of exposure Results in…. epidemics impact the entire community contribution to re-emergence of inf. dis. 30  4. Modern Cities, Disease, and Culture Culture has altered our relationship with our physical and biological environments 31  Disease and Culture Legionnaire’s disease – Pneumonia-like symptoms – Legionella bacteria – AC duct systems, hot tubs, fountains Two examples: Bronx 2015; Albany 2024 32 Next time: Disease Warriors (2006) Work of early researchers to understand and fight disease Vaccines Past, present, future 33