Environmental Health & Toxicology

APES

2009

http://news.nationalgeographic.com/news/2009/01/090116-poison-video-wc.html

Some Vocab…

• WHO- World Health Organization• Health- state of complete physical, mental, and social

well being (not just the absence of disease)• Disease- change in the body’s condition in response to

an environmental factor– Ex: nutritional, chemical, biological or psychological

• Morbidity- illness• Pathogen- disease-causing • Vector- organism that spreads disease• Emergent- new, not identified or absent for last 20 years• Zoonotic- transmitted from animal host to humans

PATHOGENIC VS. NON-PATHOGENIC

• 43% of all disease-related deaths are from pathogens (insects, bacteria, virus, worms)

• 57% from cardiovascular disease, cancer, lung disease, injuries, etc.

Pathogenic

Non-Pathogenic

Morbidity & Quality of Life

• Not everyone dies from disease, but still can cause severe suffering and debilitation

• When sick…– Crops not planted/harvested– Animals not tended– Work not done– Kids not fed

• Poorest people are most affected because they live in unhealthiest environments & don’t have $ for health care.

• Lack of adequate housing, sanitation, safe drinking water causes most cases of diarrhea which is made worse by malnutrition.

PATHOGENIC THREATS TO HUMAN HEALTH

Infectious Diseases

• Onchocerciasis (river blindness)– Vector: Black fly– Many roundworms get

into eyes & die causing blindness

– Control with insecticide sprays

– Merck & Co. are providing free ivermectin to help eradicate.

Infectious Diseases

• Elephantiasis– Vector: Mosquitoes– Roundworm gets into

lymph system and blocks lymph vessels causing fluid build up in the extremities.

– SmithKline Beecham is supplying free albendazole to kill worms in body to help prevent spread.

Infectious Diseases

• Drancunculiasis- – Guinea worm– Vector: Drinking

Water contaminated with Cyclops

– 3 meter long worm that lives under skin. Forms blister & must be wound out of skin to remove

Infectious Diseases

• Hemorrhagic Fever – Some Types…

• Ebola: Vector- unknown

• Lassa: Vector- Mastomys rat species

• Hanta: Vector- Deer mice

– All cause tissue deterioration, bleeding, pulmonary edema.

– Ebola has 90% mortality rate.

– Highly contagious

Infectious Diseases

• Malaria– Vector: Anopheles

Mosquitoes transmits Plasmodium protist into host blood stream

– 3 million die each year, 90% of them in Africa

– In 1950’s & 60’s, sprayed DDT & knocked down from millions cases each year to thousands, now back to 2.5 million new cases

– Mosquitoes are developing resistance

– Fever, chills, flu-like symptoms

Infectious Diseases

• Cholera– Cause: Bacteria in

unclean drinking water– Severe stomach cramping,

severe diarrhea, vomiting– Thought eradicated in

many places but has made comeback in some due to ships dumping bilges in harbors of cities with inadequate water treatment

Infectious Diseases

• Tuberculosis– Cause: bacteria– Eliminated but has

returned stronger than ever

– Some strains drug resistant

– Spreads rapidly by respiratory droplets (coughing, sneezing, mucus)

– EX: Russian prisons

EMERGING DISEASES

Infectious Diseases

• West Nile Virus– Vector: mosquitoes or

blood transfusions, mother to child via nursing

– Symptoms: nerve problems, stiff neck, headache, high fever, etc.

– Mammals are the “dead end” infection as the virus cannot multiple in mammals

– Prevention: scan blood donations; mosquito prevention

Infectious Diseases

• SARS– Severe Acute Respiratory

Syndrome– Vector: can be passed

directly from animals (usually birds) to humans, also passed human to human

– Highly contagious!– Passed via respiratory

droplets (cough, mucus, sneeze) from human to human

– Prevention: wash hands, destroy infected animals, keep distance from animals, quarantine infected people.

SARS vs. Bird FluSimilarities• Both are potentially fatal viruses.• Both are respiratory diseases. • Both have first affected animals and then made the jump to humans. • Both have similar symptoms, including fever and difficulty breathing. • At present, there is no known cure for either virus.

Differences• Bird flu is caused by a flu virus while the SARS virus is more closely related to

the common cold. • SARS can be transmitted from person to person. So far, MOST CASES of bird

flu have only been transmitted from birds to humans.

H1N1 (Swine Flu)

• First showed in 2009• First thought to be genetically

similar to flu virus seen in pigs• Now know it has similarities to

viruses seen in pigs, birds, and humans

• Very contagious- spread from human to human

• Same symptoms of flu with high fever

Difference between Endemic, Epidemic & Pandemic

• Endemic- disease exists permanently in a region or population. EX: malaria

• Epidemic is localized outbreak of disease. EX: west nile

• Pandemic is worldwide outbreak of disease. EX: H1N1, small pox

Methods of disease preventionInsect-born diseases:• Reduce mosquito population

– Use biological control- frogs, fish, bats, birds– Wear more clothing in mosquito infested areas– Use insect repellant– Insecticides– Mosquito netting– Eliminate standing water

Water-born diseases (cholera):• Wash hands• Boil water • Shut down shellfish beds• Provide clean drinking water• Introduce sanitation for sewage

Other diseases (tuberculosis, hemorrhagic fever)• Quarantine infected individuals • Use antibiotics on bacteria (tuberculosis)

What causes disease to spread so rapidly?

• Population density , so contact • Moving into remote areas for

agriculture exposure.• Deforestation, pollution causing

local & global climate change ( in temp = in mosquito pop. And in mosquito range)

• Eliminating predators so in rodent, roach, mosquito pop.

in speed & frequency of travel (airplanes, ships) to other countries

in resistance (Malaria) = “Superbugs”

• Taking medication improperly leads to “superbugs”

• Antibiotics given to farm animals increases their resistance.