HUMAN BIOLOGY

Learning about human bioLogy 11

with—Lyme disease, which is a

major emerging disease in the

united States. it is caused by

a species of bacteria, Borrelia

burgdorferi, which ticks transmit

when they suck blood. Luckily,

most cases of Lyme disease can

be cured easily with antibiotics.

So why have so many new diseases turned up in recent

years? a few factors stand out. For one, there are simply many

more of us on the planet, interacting with our surroundings

and with each other. each person is a potential target for

pathogens. also, more people are traveling, carrying diseases

along with them. another important factor is the misuse and

overuse of antibiotics, which are not effective against viruses.

the first widely used antibiotic was penicillin, which was

mass-produced in the 1940s (Figure 1.11C). Since then,

hundreds of these powerful drugs have been developed.

they have saved countless lives and prevented untold misery.

the best way to combat any disease is to prevent it in

the first place. the common, and mostly simple, preventive

(

Figure 1.12 Hand washing and other practices can help prevent

the spread of many infectious diseases. A Preventative measures

for avoiding infections caused by microbes that are transmitted in

air, food, blood, or enter via the skin. B Staphylococcus aureus

bacteria (yellow balls) sticking to microscopic hairs on the tissue

lining a person’s nose. This strain is common in the nose, throat,

and intestines. It is a leading cause of bacterial infections in humans.

antibiotic Substance that

can kill microorganisms.

emerging disease Disease

caused by a pathogen that

until recently did not infect

humans, or did so only

rarely.

Preventative measures:

• Hand washing


• Cover mouth when coughing
  or sneezing


• Proper disposal of used tissues


• Vaccination programs

Respiratory tract

Preventative measures:

• Hand washing


• Proper food storage, handling,
  and cooking


• Good public sanitation (sewage,
  drinking water)

Digestive tract

Preventative measures:

• Avoid/prevent needle sharing/
  IV drug abuse


• Maintain pure public blood
  supplies


• Vaccination programs against
  blood-borne pathogens
  (e.g., hepatitis B)

Blood

Preventative measures:

• Hand washing


• Limit contact with items
  used by an infected person

Skin

A

B

C

C: Image courtesy of the Advertising Archives

© Cengage Learning

Juergen Berger/Science Source

measures listed in Figure 1.12 recognize that the human

body, soil, water, and other animals all are reservoirs for

a range of disease-causing organisms. you’ll read more

about this topic in Chapter 9, which considers immunity

and other forms of body defenses against disease.

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