Red tides Harmful algal blooms Ways that humans influence the growth of HAB Agricultural runoff getting into bodies of water Urban runoff Excess phosphorus finds its way into the water streams and ends up If human waste is not treated well then it contributes to the movement of excess phosphorous Most HABs today are because of excess nutrients warm water and sunlight Dinoflagellates Brevetoxin B Neurotoxin produced by Karenia breve The compound and related toxins are believed to have been responsible for massive fish kills from red tides in several regions of the world and poisonings of humans who ate affected seafood When these bloom in billions of numbers these compounds can become a big Brevetoxins open up Na channels inappropriately causing neurons to fire when problem they should not be Biomagnification The effects of toxins are more greatly felt by organisms at a much higher trophic level whales etc In 1987 a dinoflagellate HAB was implicated in the deaths of 14 humpback whales that washed ashore on Cape Cod What is a limiting factor Limiting factors are Conditions that limit the growth of a species What limiting factor could have played a role in triggering an HAB that led to the death of those marine mammals a Changes in sunlight b Changes in upwelling c Changes in nutrients d Changes in global temperature e Changes in zooplankton Change of amount of iron in the water Intentional fertilization with iron has been proposed as a way of triggering algal blooms which consume CO2 Glacial runoff from the Andes mountains led to a massive amount of iron in the water off the coast of Cerro Bellena Seemed to be spiked levels of iron in the water every 26 000 years Matched with warm periods What could be causing spikes in iron enriched runoff with a periodicity of 26 000 years Milankovitch Cycle Earth s orbit is never the same Eccentricity day Xxx year Precession wobble This happens every 25 772 years Why is the incidence of Human Papillomavirus variant 16A more common in people from Europe and Asia than in Africans UNIT 1 THE COVID 19 PANDEMIC What is the virus that causes Covid 19 How do viruses impact a host and what defenses does a host have How does a pathogen spread through a population and what controls or limits that spread VIROLOGY COVID 19 Why is the virus that causes Covid 19 called SARS COV 2 Severe Acute Respiratory Syndrome Coronavirus Glycoproteins on the surface of the envelope serve to identify and bind to receptors on host membranes If the membrane of the virus is opened it is destroyed Soap does this Since SARS first appeared in 2019 it has mutated and different forms have spread Viruses mutate and evolve at rates greater than eukaryotes and prokaryotes COMPARING VIRUSES SARS Cov 2 Belongs to coronavirus family One strand of RNA codes 4 proteins Does not integrate into the patient s genome Contains proofreading enzymes Has the lowest mutation rate of these FLU HIV Invasion of a virus is a two step process Attach to ACE2 receptor Fuse to the cell membrane via TMPRSS2 Activation brought into the cell Either block the attachment or activation RNA virus that has a special protein called reverse transcription Once infected cannot get rid of Takes RNA and makes DNA Retrovirus HIV Zoonosis An infectious disease between humans and other species From vertebrate animals to humans and vice versa Factors influencing the frequency and pattern of zoonotic diseases in a community Extent of animal human contacts Socioeconomic conditions Cultural influence bushmeat traditional medicine religious practices Climate and environmental disasters Human and animal movements Animal management intensive farming waste disposal wet markets Characteristics of agrarian societies that favor zoonosis Sharing a home environment with livestock Rural households where livestock such as chickens and Low literacy Hunting wild game Poor sanitation and hygiene bushmeat Limited human medical and veterinary facilitates Immunosuppression e g AIDs epidemic patients on chemotherapy AIDs originated in Sub Saharan Africa because of people eating Environmental disasters floods earthquakes Civil unrest war Where did SARS CoV 2 come from Bat a mammal most likely a pangolin wet market BATS Caught from the wild and eaten bushmeat Bat excrement guano is used in traditional Chinese medicine PANGOLINS All species range from vulnerable to critically endangered Victims of illegal wildlife trafficking Considered a luxury food bushmeat Their scales are said to be able to induce lactation in a mother or drain puss and help skin lesions Sell for 3 000 kg WUHAN WILDLIFE MARKET Viruses are more likely to infect different species of animals that are closely related While the taxonomic group determined to be most responsible for zoonotic pathogens varies between studies BIODIVERSITY AND ZOONOSES Biodiversity benefits human health by reducing transmission of some pathogens that have already established themselves in species In less disturbed areas zoonotic reservoir hosts are less abundant and non reservoir animals predominate Biodiversity loss makes it to be more likely that there will be spillover When biodiversity is reduced the species most likely to disappear are large bodies species with slower life histories while smaller bodied species with fast life histories will succeed longer WHAT ELSE HAS CONTRIBUTED TO THE SEVERITY OF THIS PANDEMIC Human population size 8 057 192 600 Addition of 250 000 people per day WHY IS POPULATION SIZE A PROBLEM Interconnectivity of our species across the planet With increasing growth of our species there has been a steady decrease in Habitat Biodiversity Greater opportunities for mutation and evolution of new variables ONE GLOBAL POPULATION For most species populations are geographically distinct with occasional migrants moving between populations LIMITLESS OPPORTUNITIES FOR A PATHOGEN TO MUTATE The SARS CoV 2 variant B1 1 1 7 British variant that emerged in 2020 proved to be much more virulent This variant had 23 new mutations caused 17 amino acid changes Anthroponotic Spread between humans Chimera virus SARS CoV 2 A combination of the bat and pangolin viruses When a reservoir population with a high pathogen prevalence comes into contact with a novel host population it is called A spillover event Move from one population to another Involve interactions with wildlife The infection is transmitted from the reservoir population and may or may not be transmitted within the new host population