CHAPTER 6 ENVIRONMENTAL HEALTH

ERADICATING A PARASITIC

NIGHTMAREHuman health is intricately

linked to the environment

ERADICATING A PARASITIC NIGHTMAREHuman health is intricately linked to the environment6

Main Concept

Water contamination and other environmental changes can contribute to infectious disease transmission. Better sanitation and access to public health programs, as well as clean air and water, can improve human health.

ERADICATING A PARASITIC NIGHTMARE

Human health is intricately linked to the environment

6At the end of this chapter you will know:• What environmental

hazards impact human health and facilitate the transmission of diseases

• How public health programs can reduce health problems in both more developed and less developed nations

Learning Outcomes

Environmental hazards impact human health6TERMS TO KNOW:Waterborne diseaseVector-borne diseaseInfectious diseasesPathogen

Tiny water fleas, seen as black flecks in the water supply, are responsible for worm infections that sweep through villages every year or so.While not fatal, the worms temporarily incapacitate workers, often during the harvest season. The female worms will burrow through the tissues and cause painful blisters on the skin.The simple process of filtering the water can stop the cycle of infection since the worm’s life cycle cannot be completed without a human host ingesting the larvae.

Environmental hazards impact human health6

The role of public health is to improve the health of the human population, both in more developed nations and in less developed nations.

Educating people in how to improve sanitation and other behaviors is a part of the preventative treatment provided by health care workers around the world.

TERMS TO KNOW:Public healthEpidemiologist

Environmental hazards impact human health6

Understanding different social and cultural systems is an important part of public health.

Public health professionals identify specific risks, analyze relevant information, and develop methods (cultural, social, and medical) to eliminate or mediate those risks.

TERMS TO KNOW:Public healthEpidemiologist

Environmental hazards impact human health6

Noncommunicable diseases havea more significant impact but cannot be transferred from one individual to another.Cardiovascular disease is usually the result of behavior or genetics.

Infectious diseases are those that can move from one victim to the next by a vector or another organism. Many rely on other organisms as intermediate hosts.

TERMS TO KNOW:Noncommunicable diseasesZoonotic disease

Environmental hazards impact human health6

Noncommunicable diseases havea more significant impact but cannot be transferred from one individual to another.Cardiovascular disease is usually the result of behavior or genetics.

Infectious diseases are those that can move from one victim to the next by a vector or another organism. Many rely on other organisms as intermediate hosts.

TERMS TO KNOW:Noncommunicable diseasesZoonotic disease

Environmental hazards impact human health6Many emerging infectious diseases are related to environmental changes such as climate change and habitat loss. Other causes are related to contaminated water supplies.

TERM TO KNOW:Emerging infectious diseases

Environmental hazards impact human health6Viruses must be ingested or injected by the new host. Fleas biting humans transmitted plague and the Hantavirus particles are inhaled by the victim.

Bacteria can be found in contaminated food or water. Examples include cholera, cellulitis, and E coli.

Environmental hazards impact human health6Examples of infectious diseases caused by protozoans include giardiasis and malaria.

The use of antibiotics can eliminate good bacteria which control fungal growth in the body.

Worms are an indicator of undercooked food and contaminated water.

Environmental hazards impact human health6Different parts of the world have different public health concerns.

In the U.S., loss of biodiversity has lead to increases in mice capable of carrying Lyme disease and human encroachment brings people in contact with these mice more often.

Deforestation in tropical areas increases mosquito habitat, thus allowing for an increase in malaria cases. Agricultural runoff adds nutrients and floodwaters add fecal contaminants to local water supplies, triggering outbreaks of cholera and other waterborne diseases.

Dam building and urbanization increase the amount of standing and stagnant water, allowing increasing cases of guinea worm, river blindness, and others.

Biological hazards contribute to the global burden of disease6

Biological hazards contribute to the global burden of disease6

The small copepods carry a larval form of the guinea worm.

Drinking water containing the copepods allows the larvae into the body.

The acidic environment of the stomach will kill the copepods and release the larvae which quickly move into the host’s body.

Biological hazards contribute to the global burden of disease6

After maturing and mating, the males die while the females migrate to the surface of the body and burrow out.

When the victim eases the pain by soaking their foot or leg, the female releases the next generation of worms.

Biological hazards contribute to the global burden of disease6

The larvae grow and develop inside copepods in the water.

The cycle is completed when another person drinks water containing the copepods.

Biological hazards contribute to the global burden of disease6

The cycle can be stopped several different ways:

Drinking water that has been filtered or purified

Treating the water with a mild pesticide

Not putting infected limbs in water

The factors that affect human health differ significantly between developed and developing nations6

Differences in access to medical care, sanitation, water treatment, food safety, social and economic stability, and technology can reduce the risks of environmental diseases.

The factors that affect human health differ significantly between developed and developing nations6

The factors that affect human health differ significantly between developed and developing nations6

While the leading causes of death in developing nations are infectious and communicable, the leading causes of death in high income nations are primarily noncommunicable. Leading causes of death in middle income countries is a mixture of both communicable and noncommunicable diseases.

Environmentally mediated diseases can be mitigated with funding, support, and education6

Guinea worm cases have been significantly reduced over the last 25 years. In the villages, men guard the water supply to insure nobody with blisters goes into the water. Water and food are brought to infected people until the worms emerge. Hunters carry small portable filters to prevent infection while hunting. Women teach girls the importance of filtering water before giving it to their families. These and other policies have reduced reported cases by more than 99%.

Environmentally mediated diseases can be mitigated with funding, support, and education6

New wells and ways to filter groundwater supplies are ways to provide clean water, but cost money and materials that often must be brought into the country.

Proper waste disposal and preventing runoff from contaminating water supplies can be done locally, but require trained people to educate local populations.

Environmentally mediated diseases can be mitigated with funding, support, and education6

Education programs can be used to teach people how to identify and eliminate vector habitat, such as standing stagnant water for mosquitoes.

Solar cookers can be used in areas where fuel supplies are limited or where people use animal dung for cooking fuel, reducing the pollutants in the air.

Environmentally mediated diseases can be mitigated with funding, support, and education6

Education is a key part of the solution. Eliminating pathogens, changing behaviors, and other ways to reduce risks all require educating the people.

Public and government support allows for the efficient and coordinated activities across and between different localities.

PERSONAL CHOICES THAT HELP6

UNDERSTANDING THE ISSUE6

ANALYZING THE SCIENCE6

EVALUATING NEW INFORMATION6

MAKING CONNECTIONS6