The flatworms include the tapeworms and the flukes Tapeworms that live in the

The flatworms include the tapeworms and the flukes

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The flatworms include the tapeworms and the flukes. Tapeworms that live in the intestines may grow from 5 to 50 feet in length. Imagine hosting a 50-foot tapeworm! Flukes are flat, leafshaped worms that invade the blood and organs such as the liver, lungs, and intestines. Infestation by worms is treated with drugs called anthelmintics. Arthropods are animals with jointed legs and include insects. They are of concern for two reasons. Arthropods such as mites and lice are ectoparasites, meaning that they live on the surface of the body, skin, and mucous membranes. Ectoparasites cause itching and discomfort but are not life-threatening. More seriously, arthropods such as mosquitoes, biting flies, fleas, and ticks act as vectors of disease. (A vector is an object, living or nonliving, that transfers a pathogen from one organism to another.) Laboratory Identification of Pathogens o One of these techniques is called staining and involves the use of dyes. A second technique is a culture. o A gram-positive bacterium is one that stains purple or blue. Streptococcus is an example of a gram-positive bacterium. A gram- negative bacterium such as Escherichia coli does not absorb the purple Gram stain. Instead, a gram-negative bacterium picks up a pink or red stain. Because most bacteria are gram-positive or gram-negative, Gram staining is an important first step in the identification of the causative organism of an infection. o Another stain is called the acid-fast stain . The bacterium is first stained with a red dye and then washed with an acid. Most bacteria lose the red stain when washed with acid. However, several bacteria retain the red stain and are therefore called acid-fast. The most famous of the acid-fast bacteria is the Mycobacterium tuberculosis, the causative organism of tuberculosis (TB). This organism is commonly called the acid-fast bacillus. Some bacteria do not stain with any of the commonly used dyes. o The growth of pathogens in a culture medium is called a culture.
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The Spread of Infection Portals of Entry and Exit Pathogens enter the body by portals of entry, which include the respiratory, gastrointestinal, and genitourinary tracts; and eye, skin, and parenteral route. The parenteral route includes those injuries that penetrate the skin or mucous membranes, such as bites, cuts, and surgery. Pathogens leave an infected body by portals of exit, which include the respiratory, gastrointestinal, or genitourinary tracts; the skin (intact and broken); eyes (tears), and breasts (milk). The most common portals of exit are the respiratory and gastrointestinal tracts. Salmonella organism in a person with typhoid fever exits the body in the stool. How Pathogens Spread Person to Person - The virus was spread by droplet contact. Second, your hands were contaminated with the virus, and you touched many objects in the office (e.g., doorknobs, desktops, other people’s hands after handshaking), thereby contaminating these objects. Others touched the contaminated objects and eventually introduced the virus into their own bodies. Environment to Person -mode of transmission includes contact with contaminated water, air, food, or soil. Tiny animals to person - mode of transmission includes the use of insects (and other “crawling critters”) in the spread of disease; these tiny animals are living vectors. For example, a mosquito bites a person with malaria.
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