Understanding Pollution, Pathogens, and Human Health

hi everyone welcome to this AP environmental science uh lecture on pollution in human health but mostly

focusing on pathogens and infectious diseases so we got this one learning objective on pollution and human health

and the enduring understanding is that pollutants can have both direct and indirect impacts on the health of

organisms including humans the learning objective is to identify sources of human health issues that are linked to

pollution and because it's really talking about um sources of human health that are linked to pollution like it

says we've already talked about this most of the stuff we've already talked about in

different PowerPoints whether that is PowerPoints talking about um energy production or talking about uh different

types of pollutants and their health impacts we've really hit this in many different places what we will talk about

in this PowerPoint is um dentary we've already talked about mesothelioma so we're not really going to talk about

that um we haven't really we're not going to really talk about respiratory problems and lung function being

impacted by h high levels of ozone because we already talked about that but we will just barely mention um the

difficulty to establish a cause and effect relationship between pollutants and human health we've talked about that

in class how it's really difficult to do human um studies like you cannot for ethical reasons um expose people to

varying levels of pollutants and track them um in a controlled study okay so for many reasons it is difficult to

determine a 100% direct relationship between the cause and effect of pollutants and human health

issues where we're going to spend most of our time is talk about pathogens and infectious diseases we're going to hit

all of these um all of these learning objectives or Essential Knowledge here's the vocab if you want to pause it and

jot it down so like I said um you guys are responsible for knowing the different human health impacts of the

various pollutants that we've talked about whether those are atmospheric aquatic or terrestrial pollutants so

revisit those power points because again we've talked about the human health impacts uh throughout this entire school

year okay um for the second bullet point here it is really difficult to know the negative Health impacts of many of these

pollutants the chemical industry is creating new um new compounds all the time and testing does not keep up with

the creation of new compounds and most testing is industry funded so industry does have a clear conf conflict of

interest when they create a new chemical and they find all of these beneficial properties of a new chemical those

beneficial properties may be outweighed in their mind by or sorry May outweigh in their mind the negative Health

impacts plus they get a lot of money from um marketing these chemicals for whatever uses that they are marketing

them for so there's a conflict of interest there and they may hush up studies they may pressure scientists to

fudge results to um to misinterpret data intentionally and it's really difficult for um the general scientific Community

to see their results because all of those are proprietary studies um industry studies are proprietary and

they own that data set they do not have to publish it and peer-reviewed scientific journals like a scientist at

a university would okay the other issue that we have is acute versus chronic exposure it's really difficult

to nail down whether somebody is exposed to something um like like if somebody's exposed to

something once and they get acute exposure to a p to a uh a toxin and they die from it or they get a um some other

negative health impact from it that's pretty easy to tell but if it's chronic exposure low levels of a pollutant you

know parts per billion parts per million it's really difficult to tell if somebody gets this disease because

they've been exposed to something for 30 years um at very low levels we also um do most of our studies on

mice and rats we also do studies on primates uh less often today but we still do to see if um different

chemicals are toxic however those proxy models may not represent human physiology 100% um they are very good

models for human physiology because um pretty much all biochemical processes in any mammal is the same but it may not be

100% applicable to hum you know 99.9 but maybe not 100 when we mix different um compounds in the environment we can have

um greater effects than if we were just to be exposed to a single compound and most of these tests are done with just

single compounds but if we have a cocktail of compounds um let's say in drinking water we might have um more

damage done to the humans the human body then what we would expect from just adding up the sum of those parts from

the sum of those different chemicals all right so with all that being said regulatory bodies should be

practicing the precautionary principle um when it comes to new chemicals that are introduced into the consumer um the

consumer space you guys can read the definition of the precautionary principle there but as we have seen uh

numerous times the US does not do this we essentially allow industry um to develop its chemical run its own

industry funded studies and then with without double-checking those studies um put a new chemical into the

marketplace where people can be exposed to it for years and in many cases decades and in some cases many

generations several Generations exposed to it um before we determine that there are negative effects through uh the

relatively long process of scientific experimentation and peer review and um repeating

studies the EU on the other hand at least in theory this doesn't actually happen all the time in real life but at

least in theory only introduces new chemicals once they've been proven safe whereas in the US we have a um safe

until proven guilty type of thing like innocent till proven guilty safe until proven harmful and we'll use it for

years until we determine that it is harmful and then we'll retract it only to replace it with another chemical to

replace that cycle all right so that's all we're going to talk about human health impacts um for this PowerPoint

but again revisit the old PowerPoints to see the negative Health impacts of all the various pollutants that we' talked

about um let's start talking about pathogens so a pathogen is any organism that can cause disease in another

species those can include viruses bacteria fungi protoo so those would be protees um such as malaria and then some

animals these can occur in many environments regardless of whether the environment looks clean or not and uh

let's talk about some of these pathogens but before we do that let's talk about the adaptability of pathogens so all

living things are going to have their ecological tolerances in path are no exception they have their own ecological

tolerances most pathogens are specific for a specific host right you're not going to have a parasitic wasp that

prays on aphids all of a sudden start going after spiders they are specific for specific host um organisms um

although I might not consider a parasitic wasp of pathogen but whatever um you will not give a tree a common

cold okay so that would be another example coronav virus cannot um infect trees because they are mammal specific

but more importantly they are human specific there are some cases where pathogens can jump from one host to

another we'll talk about those um so-called zoonotic diseases that originate in animals and then uh

secondarily infect humans but for the most point I for for most of the time pathogens are specific to a specific

host or a specific small set of hosts however pathogens are notorious for be rapidly mutating they are

constantly and a um in a evolutionary arms race with their host their a host always wants to um out evolve the

pathogens and the pathogens are always trying to keep up and mutating rapidly to do so bacteria can perform horizontal

genes transfers so bacteria uh do not do sex but they can uh two bacterial cells can go next to each other and create

kind of a little tunnel with their plasma membranes um going through their cell walls and um trade uh genes back

back and forth especially genes that are on plasmids so they'll they'll move plasmids um back and forth so we can

have a gene that causes resistance to penicillin um in one bacteria being transferred to another bacteria often of

the same species but not even of the same species in many cases uh viruses and um viruses can also recombine within

cells so if two similar viruses infect the same cell so let's say if a human lung cell gets infected with both a

swine flu and a human influenza virus at the same time those two um virus virus genomes can get repackaged into one

virus and then um you know released when that cell ruptures to release those viruses however despite the mutability

of pathogens um there are some pathogens that we have more or less eliminated um the greatest example of that the best

example of that is small pox um there was a massive small small poox campaign in the mid 20th century uh to eradicate

it around the world and it's believed to be eradicated um By 1979 and the only smallpox that exists

today as far as I know is in Labs um the other vaccine triumphs include polio measles rubella um even

though we have some instances of those that are not completely eradicated we um have very very very low numbers of

measles mums rebella Etc um because of vaccination campaigns that's not to say that every single

campaign that we've done against um against uh pathogens have been successful for example the malarial

campaigns of the 1950s and 60s were unquestionable failures they were they were disasters but malaria is a very

different um pathogen than these viruses were all right one thing with environmental science that is really

important with um connection to disease is the incidence of emergent diseases and how emergent diseas diseases have

increased um throughout the 20th and 21st centuries so an emergent disease is a disease that is new to the human

population they're usually jumping from animal hosts to um secondarily infect humans so they're an example of the

zoonotic diseases that I mentioned before um and just a few highlights you guys can see the list of the emerging um

diseases that we've had throughout the 20th and 21st century so far um swine flu the great influenza the Spanish Flu

of 198 1919 um killing hundreds of thousands of people worldwide coinciding with World

War I or at least the end of it um the virus that causes Ebola um first noted in

1976 shortly after that the virus that um causes AIDS so the HIV virus um and then you know we've been

living with that for the past um whatever 43 years SARS K2 definitely

um very familiar you guys are very familiar with that however we there is some debate about where that truly

originated but it is still an emergent disease whether it originated in animal or if it originated in a lab but I want

to highlight one of these emerging diseases which is uh Bolivian hemorrhagic fever or machupo um this

emerged in the 1960s so what I want you guys to imagine is that you're in South America you're in Bolivia you're on

Bolivia's Eastern Frontier so if we look at the map of Bolivia we're seeing the Andes mountains running through the more

Western portions of Bolivia and then the North and Eastern portions um are getting down into the um Amazon basin

and imagine that you're in a small town it's basically like a cowboy town it's a Frontier Town there's dirt roads there's

no um no uh running water no running uh no electricity um imagine basically like you know early 1900s Cowboy town in the

United States okay and in this town of saning um there is a fever that starts to break

out and people start to um start to bleed from their nose their mouth their eyes and everything and then people

start dying and when the health authorities um got there they found that this um was a new virus that was coming

from Mouse populations in that area and essentially what they were doing as they were moving further and further and

further with these Frontier towns into what was previously n u natural habitat previously untouched forest in

Savannah the mice populations were moving into people's homes you were uh destroying Mouse habitat and rather than

Mouse the mice just dying they moved into people's homes and they had a ready food supply of um corn for the most part

in these people's homes so they would eat the they would get out at night eat the corn they would pee they would um

defecate on the corn on their sheets on their floors on their like wherever and this virus was transmitted through their

urine um to people so they were um even the dust from the urine like the the mouse Peas on the floor you sweep the

floor and you inhale this dust you can get the virus um transmitted to you in that way so as people are moving further

and further into natural habitats we are becoming more and more exposed to populations of different organisms and

we're increasing the incidence of or at least the possibility of viruses jumping from one host to another in this case

from a mouse to a human now this virus um is a hemorrhagic fever meaning that the capillaries essentially fail the um

the I believe in this case the uh diameter of the capillaries increases so much that this that this lining of the

capillaries becomes really really really thin and allows blood to leak um into the interstitial tissue this leads to

headache fever fatigue bloody stool bloody vomit blood in your Airways so you're coughing up blood and people

start to bleed from the nose the the mouth the eyes and you have excruciating pain all over the body and about um 50%

of the town of San haen was affected and between 25 and 50% of the infected die so upward estimates of 25% of the town

dying from this um it is more or less controlled today we know where it comes from we know what actions to take to

keep the mice out of the homes but this is what I'm talking about with emergent diseases a disease that was never in the

human population before um or at least never documented in the human population and then as we're moving further and

further into natural habitat we are becoming more and more exposed to these uh animal population so that diseases

can jump all right but machupo Bolivian hemorragic fever is not one that you

need to know for the AP test these are the ones that you need to know for the AP test so this is uh what's on their AP

standards and these are the ones that we're going to focus on so just getting right into the first one plague this is

known as Bubonic plague sepic plague the Black Death you've probably heard about this in history class this is caused by

bacteria that resides in fleas the bacteria is Yia pesus and the vector is the fleas so a vector is a um is like an

animal that can transmit the disease uh not specifically the animal itself but the animal is carrying the disease the

pathogen the disease organism and can move it uh to humans so the vector in this case is fleas rats or any other

rodent um carried the fleas so people thought that rats got people sick but it was actually the fleas on the rats that

would jump from the rat to the person and then bite the person and give them um the plague bacteria infect them with

the plague bacteria now this is environmentally dependent because the fleas can pass the bacteria at high

temperature um meaning that they get rid of the bacteria in their feces but the bacteria are going to Lodge in their gut

at low temperatures it's going to make them feel like they're constantly hungry the fleas are going to be constantly

hungry and they're going to um bite more and more and more people and because that bacteria is in their gut they're

going to um they're going to give people that uh they're going to inject people with that bacteria or um the bacteria is

going to infect uh the person wound around the mouth parts of the flea and they're going to um infect the person

with uh the bacteria and cause plague all right and we're going to skip most of the history stuff even though it

is really interesting um I have it up here if you want to read it um but plague is currently endemic to um North

and East Africa it's endemic to Eurasia it's endemic to North America uh so plague is pretty widespread and again

it's still carried on fleas on rodents um including prairie dogs here in Colorado so I would never approach a

prairie dog because if you get fleas on them from them um on you it could carry plague not a guarantee but it could okay

the plague bacteria the urenia pesus bacteria is going to proliferate it's going to reproduce in your lymph nodes

and that's um one of the most Insidious things about this bacteria because your lymph nodes are part of the lymph system

the U the lymphatic system that is responsible for uh for killing and removing the pathogens from the body so

they um they proliferate in the same organ that's that's responsible for that they're basically immune to many of the

white blood cells including macrofagos which are responsible for phagocytosing um uh pathogens they basically engulf or

eat pathogens you probably remember that term from um biology class so macrofagos will engulf or um take in foreign bodies

and in this case a uh a bacterial cell okay but uh the urenia pus bacteria is let's just say immune to that the

symptoms of plague um you can in increasing order first get Bubonic plague this is where you get fever

headache chills uh swollen and painful lyph nodes um and those lyph uh swollen lymph nodes are called bubos which is

where Bubonic plague comes from the second um part is septicemic plague this is when the Bubonic plague goes further

and gets worse and that's going to be fever chills the skin is going to turn black and die so you see an example of

somebody's hand up in the top um that has septicemic plague um and you can have internal hemorrhaging and it can be

fatal and then finally is pneumonic plague and that's where the bacteria is going to get into the lungs and it's

going to cause fever and pneumonia and the mortality rate is above 90% so it's essentially a death sentence to get

pneumonic plague and it's at that point that it can be transmitted from one person to another via respiratory

droplets um so that's a secondary way that uh plague can be transmitted is through respiratory droplets if it is

infecting the lungs as neonic plague all right speaking of the lungs let's talk about tuberculosis or TB this is also

known as consumption so if you read a old book um especially written in the early 1900s uh or before 1800s um 17

100s they'll often call it consumption even Shakespeare I believe called it consumption um this is caused by the

bacteria mob bacterium tuberculosis um so it is a bacterial infection you guys can see the symptoms

up at the top right for people that have active TB this is going to spread through respiratory droplets um so you

guys are very familiar with those from covid but it's coughing sneezing even talking and spitting whenever you have

Micro droplets of um saliva that are getting ejected from the mouth of through any of these activities it's

estimated that about a quarter of the world population has tuberculosis but it's latent tuberculosis meaning that

they are infected but the immune system keeps that infection under control and they show no symptoms whatsoever so the

bacteria is in the lungs but the immune system is preventing any symptoms from being shown it's keeping that bacteria

in check but if somebody becomes stressed if their immune system um gets uh stressed in any way or if the

bacteria proliferates so much that it overrides the immune system um they can develop active TB and this is where you

have um heavy chronic coughing you often cough up blood you have fever and you have weight loss um and that's also why

it's called sometimes wasting disease and that's where consumption comes in because it's like the body is is uh

wasting away um about 10% of latent TB cases become active and active TB cases have a 50% mortality rate now where does

this play into environmental science primarily with them being um drug resistant back um bacteria so TB is

notorious for developing drug resistant um drug resistance so they because it's a bacteria it is often treated with

antibiotics however those antibiotics um can lead to the natural selection of drug resistant tuberculosis strains and

once one strain becomes um becomes uh resistant to One Drug you might use a second drug which would lead to multiple

resistant tuberculosis and then you also have extensively drug resistant tuberculosis or totally drug resistant

tuberculosis we have seen strains of any of these from the mid 1980s but they're becoming more widespread and common

throughout the 2000s you guys can also see where the incidence of tuberculosis around the world is we've mostly

eliminated it through the united in the United States and the rest of North America however it is still very

prevalent in um Africa and Asia all right all right so how do bacteria become antibiotic resistant

it's basically the same process that we talked about uh pests becoming pesticide resistant whether that is weeds becoming

herbicide resistant like we talked about with glyphosate or if it's um resistance to any other uh pesticide so you start

off with a population of um bacteria in this case and in those bacteria maybe one of them just mutates to become

randomly antibiotic resistant it's a random mutation but then we introduce a selective pressure that selective

pressure is the antibiotics that kill all of the other bacteria and that one um that uh that is antibiotic resistant

survives when it survives it replicates it multiplies and you form a population of antibiotic resistant bacteria and

those bacteria can perform conjugation and do horizontal Gene transfer and pass those genes from one

bacteria into another sometimes uh most of the time the same bacterial species but often times it can be different

bacterial species as well this can happen to develop drug resistant tuberculosis multiple drug resistant

tuberculosis Etc it can also be occurring in uh different populations of bacteria whether those are eoli or any

other bacteria um we can have antibiotic resistance but in the context of tuberculosis um antibiotic resistance is

what you should know the next disease that we'll talk about is malaria malaria is caused by several species of

plasmodium parasites uh these are not procaryotes they are not bacteria they are instead ukar they are in that kind

of fifth Kingdom of life um that we use as a junk drawer for basically anything that is single- celled eukaryotic that

isn't clearly a plant animal or fungus so it is a protoo okay um you don't need to know the species that are involved

and you don't really even need to know that it's aniles mosquitoes but the vector for the malarial parasite is

female mosquitoes they will bite you inject you with the malarial Paras site that is contaminating their mouth Parts

okay um passing it from one person to the next via their gut it's estimated that about 400,000 deaths occur annually

from malaria most of those are children about 2third of all those deaths and the fertility rates vary by age and previous

exposure if you've been exposed before and survived that initial infection then you're going to be um more likely to

recover from any subsequent infections plus there is different species of the plasmodium parasite with different

mortality rates which we don't really need to go over the anopheles mosquito that transmit malaria is a tropical

mosquito so you notice that malaria is confined to the tropics there used to be cases of malaria in uh the Southern

United States so if you read old literature like from the 1800s um you'll see that malaria cases occurred in the

Gulf States Florida um and in the Southern United States however today we don't have many malaria cases in the

United States at all it is really confined to the tropics however that is expected to change that malaria is

expected to start having higher incenses in southern Europe Australia Southern United States as global warming occurs

and the range of these tropical and subtropical mosquitoes extends into higher latitudes so that's really what

the environmental impact of this is or the environmental connection is that malaria and other mosquito uh tropical

mosquito born diseases are expected to uh move into the higher latitudes as the planet warms

and those mosquitoes ranges um expand into those higher latitudes so there's a number of efforts

that we can you um take to uh prevent the spread of malaria there are a number of drugs that are used to treat it first

off but there are drug resistant populations of those plasmodium viruses that have existed for uh decades at this

point there is no vaccine for malaria and vaccination efforts have largely failed or totally failed

there are preventive measures though the most common preventive measure is um mosquito nuts and other type of uh

screens so like screen doors screens on Windows those types of things you can use insect repellant which can come with

their own unint and unintended consequences you can use insecticides which definitely come with unintended

consequences um especially the elimination of non-target species and stuff like DDT still being used to spray

for mosquitoes despite its well-known and well documented environmental problems um draining of standing water

where anop mosquitoes breed is another huge way to um prevent the spread of the malarial parasite because if you don't

allow for those mosquitoes to breed in that area then they're not going to be there to even transmit the disease in

the first place however as we see from this quote by Dr wi um kamami from the director general of tanzania's National

Institute for medical research saying that what you do when these mosquitoes can breed thousands of Offspring and

they puddle the size of a hippo foot during the rainy season there's absolutely nothing and then you see the

scale of a hippo's footprint versus a human's footprint or a human's foot and you can have thousands of mosquito

larvae in just that one small pool so during the rainy season it's really impractical to drain all standing water

because um it's too big of an effort it's it's impractical however there are some ways that we can prevent uh malaria

in terms of draining water such as tires so used tires that are dumped should be slashed before dumping so that they

natural so that they will just drain water you should not have um rain collection barrels or buckets or any

type of standing water in malarial zones when um they are in the breeding season I mean sorry the mosquitoes

breeding season is basically all year round um but if you do have those they should be covered they should be

inaccessible to the mosquitoes another thing that is being used that is not up here is releasing sterile male

mosquitoes and as sterile male mosquitoes will breed with females they won't produce any Offspring they won't

produce any eggs that are fertile and that will reduce population numbers so you can genetically modify male

mosquitoes to be sterile release them in large numbers um so that they're a decent or significant portion of the

population and thus um the females mate with them and lay sterile eggs or don't lay any eggs at

all our next disease is West Nile Virus um this is the same viral genus as several of our other um tropical and

subtropical uh diseases that you see listed here this is a zoonotic disease so the rest of the ones that we've

talked about have been old diseases that have um that are endemic to humans but this is our first zootic disease this is

a disease that originated in animals and then jumps to humans so humans are not the normal hosts humans are a secondary

host the event of when a um zoonotic disease jumps from a primary animal host to humans is called spillover so that's

the vocab word for that uh the normal host are over 300 species of birds and the vectors are mosquitoes but in this

spe in this uh case the genx klex mosquitoes um wnav virus can infect humans other primates dogs cats horses

um but most of those are dead end hosts but they can have mortality rates in humans about 80% of the infected will

show symptoms 20% oh sorry will show no symptoms 80% of the W cases in humans will show no symptoms and most people

won't even know that they have West Nile Virus 20% will develop West Nile fever and less than 1% will develop severe

symptoms so it's small portions that uh develop severe symptoms we can contrast that with horses where over 40% of us

horses that have been affected have died so it really is species specific about where um what the mortality rates are

westn virus was first identified in Uganda in 1937 which is why it's called West Nile because it's um identified

from around the White Nile which is the West Nile um so named after the river there was a rapid spread out subsaharan

Africa in the 1990s it was detected in Morocco so jumping across the Sahara Desert by 1996 and then in southern

Europe and Israel the Middle East by 1998 and the US in 1999 now it is endemic to large portions of North

America including all um the three largest countries in North America and much of the Middle East and Central Asia

Australia some South Pacific um areas as well now what I what do I mean by a um deadend host so a dead-end host means

that once a human is infected with West Nile Virus if a if another mosquito bites that human and sucks

their blood out they will not get get the West Nile Virus and they will not be able to transmit that West Nile Virus to

an addition to another person so from birds you can go from bird mosquito back to bird once it gets to humans you can't

go from Human to any other organism okay so it's a deadend host the next couple diseases that we'll

talk about are SARS and Ms SARS stands for severe acute respiratory syndrome this is caused by a virus called SARS

coov V1 you might uh recognize that um the this is a zoonotic disease that originated in horseshoe bats in Asia and

then went to a um Asian palm civit and then to humans so there was that intermediate host between the primary

host of the bat and then humans this was first identified in China in 2002 the outbreak was in 2004 um and there were

no cases since 2004 so it's believed to be eradicated in humans however we are monitoring the situation worldwide and

um keeping uh that it is not um not in doesn't doesn't occur in humans again between 2002 2004 there were

8,422 um people that were infected and the case fatality rate meaning that of the people that were infected dying it

was 11% this is the reason that we were so worried about SARS K2 or

covid-19 um when it uh when it emerged because even though the case fatality rate was much much lower I've seen

estimates anywhere between .5 to 3.5% for SARS K2 we at the very beginning took a lot of precautions because what

if the case fatality rate was 11% what if one out of 10 people that's contracted uh covid-19 ended up dying

that would have been much much much worse of a pandemic than it was so that's why we took so many precautions

at the beginning because this was the model the only model that we were able to use as a baseline comparison of like

what is the new virus uh covid-19 going to going to uh turn into so this spreads just like covid-19

through respiratory droplets the symptoms will include fever cough muscle pain complications and leading to

secondary infections such as pneumonia um pneumonia is actually the biggest killer here because um pneumonia is a

secondary infection and leads to in many cases um just more complicated and more um severe respiratory issues that can

lead to death and then Ms is a very similar type of Corona virus um it is the Middle East

Respiratory Syndrome and it's uh the virus itself is the Middle East Respiratory Syndrome related Corona

virus which is definitely a mouth load and this was first identified in 2012 there were over 2,500 cases worldwide

mostly in the Arabian Peninsula and this had a case fatality rate of 35% so imagine if one out of three people that

contracted covid-19 um died from died from it so again SARS and Ms is why we took covid-19 so seriously until we um

were able to ease lockdowns and ease restrictions because we determined that the case fatality rate was much much

less than these other two more transmissible um viruses or sorry these other two much less transmissible

viruses SARS K2 is super easily transmitted um Ms less so so it uh has never really escaped the Middle East

that we know of all right another emergent disease is zika virus the vector for this is 80s

genus and mosquitoes again you don't need to know the genus of mosquitoes um for this class but I have it up here

anyway and this can be sexually transmitted so um it is a sexually transmitted disease as well the first

instance of zika virus was identified in 1947 in the zika forest of Uganda um which has two eyes whereas the virus

just has one I don't know why and it's known from equatorial Africa Asia since the 1950s and then spreading to the

Americas in 2007 most likely due to um either humans that were contract that contracted it move um moving across or

mosquitoes that were smoke that that that were um that were still ways on ships moving

across the symptoms the adults they're typically none but you can have a mild rash fever joint pain Etc and it can in

very rare cases lead to Gan bar syndrome which is the rapid onset of muscular wasting but the main concern for zika is

with pregnant mothers you have vertical transmission from mother to child during pregnancy and this leads to microsopy um

in babies so you see a baby with micral here and then a baby with severe micro sey and the dotted line showing how big

the brain should be obviously if you're born with a much smaller brain than usual you're going to have much a very

severe cognitive impairment um as with other tropical born uh tropical mosquito born diseases

the rain of zika is expected to expand um into higher latitudes with climate change so just like we talked about with

malaria the last couple illnesses that we'll talk about are both gastrointestinal or diarrheal illnesses

the first is cha which is um caused by the bacteria viool this is transmitted via

contaminated water water that is contaminated with human fecal matter it can also less commonly become um come

from eating undercooked uh Crustaceans like shrimp or crab because these um bacteria can attach themselves to the uh

to the crustacean kiten exoskeleton and then be transmitted to humans that way it can also form on um sporlike forms on

the inside of algae like inside of algal cells inside of cyanobacterial cells and be transmitted uh that way as well and

eventually get into a human host however that is much less common so the two ways are coming from um water that is

contaminated with uh human feal matter and then from Seafood specifically uh crustations where that uh bacteria can

attach to their kiteen exoskeletons and then be ingested if it's raw or undercooked this is very old disease

that is endemic to the Indian subcontinent southeast Asia there are no known animal hosts of the disease it's

just a human disease the symptoms include VI watery diarrhea and that's how most people die

is through the dehydration that is caused by the diarrhea as well as the electrolyte imbalance so you lose so

much fluids um that you uh that you end up um dehydrated and die the case fatality rate um a severe cases is

between 25 and 50% depending on treatment there's an estimated 3 to 5 million people affected annually with

25,000 to 135,000 Deaths but again um on severe cases 25 to 50 % mortality rate the treatment is just going to involve

waiting it out and giving the patient lots and lots of fluid so when we talk about Chala and the next one which is

denter um clean drinking water is really uh the main solution for this so proper sanitization and clean drinking water

whether that is coming from a water treatment facility and then pumped to people's homes or whether it's coming

from uh boiling your water or if it's coming from Individual water filtration systems

okay um having proper sewage treatment is also critical and getting proper sewage treatment and clean Municipal

Water Supplies to people in developing nations is really the best way to uh prevent and to prevent Cola from

occurring you can also have like I said individual water filtration systems so you see two examples of those up here on

the top the first is a uh device called a LifeStraw which you actually may have if you're an avid camper or Backpacker

um I have one for when I'm camping and um you know it's definitely been you like paid for itself in use basically

what you can do with this is that has several layers of filters that can that um are are the pore sizes are smaller

than the bacteria so it will capture that bacteria through the filtration system in this as you're sucking water

through this LifeStraw um from whatever dirty Source it is another example is shown here on the um kind of the Middle

where we have a filtration system that is doing the same thing but on a larger scale with um very small Micron filters

and making clean water down at the bottom okay there has been uh you guys don't

need to know the history behind Chala but there has been seven major Coler pandemics in the last 200 years so when

we're talking about a pandemic we're talking about a global epidemic so um there's been many smaller epidemics as

well but just in the last 2 thou 200 years there's been seven major chalera pandemics so the last disease that we'll

talk about is dissenter dissenter is not a single disease but rather it's a group of diseases that all have similar um

similar symptoms which include inflammation of the gastrointestinal tract which leads to bloody diarrhea and

most people are going to die from dehydration just like um just like with chera it's very old disease and again

it's caused by several types of pathogens you don't need to know any of the specific pathogens but but it does

um it is caused by many pathogens such as shagel Giardia which you might have encountered in Colorado I know I've

gotten denter from um Gardia before you know camping and and drinking water that I thought was clean and it wasn't clean

and I didn't have a LIF straw at the time the Lifest would have prevented that but I was drinking um fresh snow

melt uh in a creek being stupid um anyway the sources of the organisms contaminated water are going to be

exactly the same for um except this is a more worldwide and it's a little bit more um prevalent because there's more

organisms that can cause dissenter than um than chora the solutions for it are the exact same as well sanitation clean

drink and water okay and you can see the number of cases and the deaths every year most of those are going to be in

the developing world because that's where um that's where water uh that's where wastewater treatment facilities

are and uh and water treatment facilities are less common all right so why did we go through all of these

diseases why are we talking about these in an environmental science class well they have some common environmental

things these are in no specific order but I'm just have them up here in this order the first one is sanitation and

clean drinking water are critical to controlling water born illnesses dissenter chalera you need to have

proper sanitation and clean drinking water in order to control for those diseases wastewater treatment facilities

drinking water treatment facilities until um until we get those in every Community worldwide we are going to have

incidences of Cher and denter number two as the climate changes the ra the ranges of pathogens and their

vectors is going to shift you're going to have um tropical and subtropical illnesses expanding into the higher

latitudes as the tropical and subtropical mosquitoes can survive um in those higher latitudes as the planet

warms okay for number three three pathogens evolve rapidly and some can become antibiotic resistant and even

vaccine resistant the overuse of antibiotics and our medical system has accelerated this okay so just like we

talked about with um with tuberculosis number four increased penetration into wild areas exposes

humans to zoono diseases which have the potential to jump to humans so as we um as we destroy habitat and as we encroach

further into Wild Spaces we have the potential to encounter more and different types of animals for them to

invade our homes although I would argue that we are invading their habitats and for those diseases that are for millions

of years been in just this one animal host to potentially spill over to the human

population number five Global Travel rapidly spreads pathogens so we saw this with uh SARS K2 Global Travel is going

to easily spread pathogens all around the world so even though we didn't talk about it in the lecture it's here um the

world is becoming a smaller place and you can go from one continent to another in the matter of you know hours to days

and you can bring your pathogens with you and then number six High population densities including those that come with

urbanization lead to Rapid spread of disease and we talked about that mostly in the context of um animals and

agriculture but whenever you see high population densities whether that is humans or animals or plants know that

disease can spread really really quickly as opposed to when you have low population

densities all right for the learning objectives um again we talked about several of these in different lectures

so I'll have you go to um those different lectures to see some of them but we did talk about dentary and we did

talk about um some of those ways that's difficult to establish a cause and effect relation relationship between

pollutants and human health issues and then finally um the pa the pathogens and infectious diseases so

pathogens adapt to take advantage of New Opportunities and infect and spread through human populations um hopefully

you saw a little bit of that in every single one of these or at least most of them specific pathogens occur in many

environments whether or not that appears clean and then we talked about how um as climate change shifts the range of those

um disease vectors is going to shift as well and then low income and poverty stricken areas are more likely to have

um dissenter chalera or any other waterborne illness we talked about plague we talked about TB we talked

about malaria we talked about West Nile SARS and Ms zika and Cera so if you guys have any

questions please let me know hope you learn something new and I'll see you all in class bye