Biological Hazards

Not Just Toxins and Pollution: It’s not just toxic chemicals and pollution. Many problems in today’s world are caused by organisms that carry disease!

Today we have outbreaks of diseases that did not exist or that people have never heard of 100 years ago. Some examples are AIDS, West Nile, Hantavirus, and mad cow disease. Many diseases that have killed people for centuries kill even more today like Malaria, tuberculosis, yellow fever, and hookworm. What are some diseases that had outbreaks a couple years ago or even today?

One of the reasons these diseases are now widespread is that we have altered and changed our environment in ways that encourage them to spread.

Pathogens: Organisms that cause disease are known as Pathogens. Whooping cough and tuberculosis are spread from person to person through the air. (Airborne disease) Cholera and giardia are spread by drinking water. (Waterborne disease)

More Pathogens HIV/AIDS is a STD (Sexually transmitted disease). It is passed from person to person through bodily fluids. Don’t be a FOOL wrap your TOOL. Don’t be silly, Wrap your willy. No glove, No Love. If you can’t shield your rocket, leave it in your pocket.

Some African bats are hosts/vectors for what disease? An organism in which a pathogen lives all or part of its life is known as a Host. Mosquitoes are a Host for malaria but also a vector. A vector means that they are the one that transmits it to another organism. Some African bats are hosts/vectors for what disease?

Symptoms of Ebola include: -Fever -Severe headache -Muscle pain -Weakness -Fatigue -Diarrhea -Vomiting -Abdominal (stomach) pain -Unexplained hemorrhage (bleeding or bruising) Symptoms may appear anywhere from 2 to 21 days after exposure to Ebola, but the average is 8 to 10 days. If Ebola is transmitted through fluids would you consider it a STD? why or why not?

Deaths from diseases in 2015 (WHO): Disease and Examples Cause Estimated Deaths per year in millions. AIDS Virus 2.9 million Diarrheal diseases (Cholera, typhus, typhoid, dysentery) Bacteria, viruses, and parasites 2.1 million Tuberculosis Bacteria 1.7 million Malaria Parasitic protist 1.1 million 11,315 people died from the Ebola outbreak back in 2014. Thanks mostly to the combined efforts of the U.S. and other countries to control the outbreak. If we didn’t do anything to control the outbreak it is believed it could have been in the hundreds of millions.

Nearly ¾ of all infectious diseases are transmitted through water. Waterborne diseases: Nearly ¾ of all infectious diseases are transmitted through water. Local water supplies in developing and non-developed countries are use for drinking, washing, and sewage disposal. Remember: A vector like a mosquito is an organism that can transmit diseases to people. What has caused an increase of vector-Bourne diseases?

What has increased vectorbourne diseases? Construction of irrigation canals and dams especially in the tropics/subtropics has increase the habitat and area of vectors. The increased air travel with recycled A/C has given diseases an ability to travel large distances and infect more. There are millions of species of animals that have not been discovered yet. The same goes for microorganisms. There are diseases all around our natural world and as we destroy ecosystems they can be released. For example the three gorges dam in China has created a huge freshwater lake. This lake is the habitat of a snail vector for schistosomiasis, an incurable disease that has become more common since the dam was finished.

Habitat destruction can lead to the next plague… As we destroy our forest and produce more CO2 in the atmosphere a bunch of things are happening. It’s getting warmer, species are going extinct, climates are changing (some areas are colder than normal or warmer than normal, seasons are getting longer or shorter, migration habits are changing in many species. But one of the biggest issues is the thawing of the permafrost and the melting of our ice caps and sea level rise. There are unimaginable diseases throughout history that have killed many organisms in some very awful ways and some of those diseases have been trapped in the permafrost & ice caps and they are being released…

Malaria: It is believe almost half of the people who have ever lived in the history of the world have died from malaria. (110 billion people have lived on earth so around 50 billion have died from a single disease). Malaria is a waterborne disease and a vectorbourne disease. It was also once the leading cause of death in the world. Malaria is caused by a parasitic protist, and is transmitted from the bite of a female mosquito. Mosquitos lay their eggs in stagnant water (still, non-moving), this is where the mosquito larvae develop. There is NO vaccine for malaria, only preventative measures.

Malaria & Climate Change: Epidemiologists believe that climate change increases the areas in which malaria occurs. Malaria has been spreading all across the globe slowly but surely. We have controlled mosquito populations with pesticides in the U.S. but now the mosquitoes are developing a resistance to them meaning we can see a resurgence of malaria cases in the near future.

Malaria in Kenya

Environmental Change and disease: We alter the environment. When we alter the environment sometimes we make the environment more suitable for pathogens to live and reproduce. Soil is often polluted with chemicals and pathogens. When soil erosion takes place these pollutants can blow away and wash away with the soil and contaminate areas thousands of miles away. Example: Hookworm

Hookworm & Soil Hookworm is a parasite that spreads through the soil that is contaminated with feces. Walking barefoot can make you susceptible. In 1984, 87 percent of the population of Nepal was infected by worms because of contaminated and eroded soil.

Emerging viruses Emerging viruses are viruses unknown 100 years ago. Ex. AIDS (acquired immune deficiency syndrome). Most viral diseases enter the body through a cut or mucus membranes. Very few effective drugs. The drugs that do work are specific to certain viruses.

Our main defense against viruses are vaccinations. But there is a problem with vaccinations, they are very specific and viruses evolve rapidly. When a new strain of a viral pathogen emerges we must develop a new vaccine. Ex the Flu. HERD IMMUNITY – Once enough people are immunized, an outbreak becomes significantly less likely!

Cross Species Transfer: A disease that has moved from one species to another is a cross species transfer. Examples of cross species transfers are HIV and West Nile virus. These pathogens were in wild animals for many years until they invaded humans. This comes back to environmental change. We’ve changed the environment so much and come into contact and spread diseases rather easily compared to any other time in history.

Predicting the worst possible scenario: Many epidemiologists believe that a future epidemic will happen soon. They also believe that influenza (flu) virus will be the cause. The flu virus is highly contagious and is a cross species transfer from many birds. We make new vaccines for new strains of the flu virus each year. Epidemiologists are afraid that soon there will be a very virulent strain that cannot be vaccinated in time that would spread through populations rather quickly.

Outbreak VS EPIDEMIC VS PANDEMIC A disease the unexpectedly occurs in a large number in a community or region that can last from days to years is an Outbreak. A disease that spreads really quickly to a lot of people in a larger area like a country or countries is called an epidemic. A disease that spreads globally or world wide is called a pandemic.