Agents of Disease

Mrs. Pittaluga

8th Grade Science

Viruses

H1N1 Virus

http://www.examiner.com/article/swine-flu-h1n1-pandemic-should-not-mean-panic

Characteristics

• Nonliving

• Neither a prokaryote or an eukaryote• Prokaryote – no nucleus

or other defined organelles

• Eukaryote – nucleus and defined organelles

Varicella Virus – Chicken Pox

http://en.wikipedia.org/wiki/Varicella_zoster_virus

Other Characteristics

• Neither a heterotroph nor an autotroph

• Reproduces by invading host cells

• Two parts:• Protective protein outer coat (called the

capsid)• Inner core that stores genetic material

• Because viruses are non-living, antibiotics are ineffective.• Immunizations help prevent viral infections• Anti-virals are typical method of treatment

(Tamiflu)

Method of Infection

• Invades a cell and reproduces inside the cell until it splits open and destroys the cell

• How Viruses Attack

Common Viruses

• Common Cold

• Flu – H1N1 (Swine Flu), Bird Flu (H5N1)

• HIV/AIDS

• Chicken Pox/Shingles

• Polio

• Rabies

Bacteria

• Living

• Prokaryote – no nucleus

• Single celled organism

• Good and bad bacteria

http://www.terrebonneonline.com/b2eukpro.htm

Other Characteristics

• Both heterotrophs and autotrophs• Heterotrophs gain their food from other organisms or

from food other organisms make.• Autotrophs gain their food by capturing and using the

sun’s energy

• Rapid growth by means of either asexual (binary fission) or sexual reproduction (conjugation).

• Different shapes – spiral, round, rod-shaped

• There are approximately five nonillion (5 x 1030) on Earth

• The study of bacteria is bacteriology, a branch of microbiology

Shapes of Bacteria

• 3 primary shapes• Spherical (cocci/coccus)

• Streptococcus (Strep throat, Scarlet fever, pneumonia)

• Rod-shaped (bacilli/bacillum) – Most common shape

• Salmonella

• Lactobacillus acidophilus (yogurt)

• Spiral (spirilli/spirillum)

• Cholera

• Lyme Disease

http://www.desktopclass.com/education/fafsc/structure-of-bacteria-part-1-f-sc-biology-chapter-6.html

Method of Infection

• Some bacteria invade cells directly

• Some bacteria produce toxins which damage cells

• Can be treated with antibiotics• Amoxicillin (Amoxil)

• Ciprofloxacin (Cipro)

• Azithromycin (Zithromax)

• Trimethoprim/Sulfamethoxazole (Septra)

Cholera Bacteria

Diseases Caused by Bacteria

• Strep Throat

• Tuberculosis

• Anthrax

• Bubonic Plague

• E. Coli

• Necrotizing Fasciitis (“Flesh-eating bacteria”) – Streptococcus pyogenes

• Acidophilus (good bacteria)E. Coli Bacteria

ProtistsThe Kingdom of Protists are kind of like the misfits. They contain a variety of characteristics that do not place them in any of the other kingdoms of life. (Monera – bacteria, Fungi, Plantae and Animalia)

Protists

• Living

• Eukaryotes – they do have a nucleus

• 3 primary types• Plant-like

• Animal-like

• Fungus-like

Other Characteristics

• Usually grow in wet places

• Most are heterotrophs

• Three forms of movement• Flagella

• Pseudopods

• Cilia

• Some are parasites to humans

Method of Infection

• Drinking contaminated water

• Eating contaminated food

• Sustaining an insect bite

Diseases Caused by Protists

• Malaria (Plasmodium)

• Giardiasis (Giardia intestinalis)

• Amoebic dysentary (Entamoeba hystolica)

• African Sleeping Sickness (Trypanosoma)

Fungi

Characteristics

• Living

• Eukaroyotes

• Heterotrophs

• Use spores to reproduce

• Are decomposers

• Live in damp, warm places

• Some are parasites to humans

Classification of Fungi

Club Fungi Sac Fungi Zygote Fungi

Methods of Infection

• Spores from an infected person can survive on damp surfaces (showers) and infect skin

• Growth on skin:• Asexual reproduction – budding• Sexual reproduction – Hyphae of two fungi

grow together and exchange genetic material

Diseases Caused by Fungus

• Fungal Meningitis (not contagious)

• Jock Itch –Tinea cruris

• Athlete’s foot

• Ringworm

Helminths

• Multicellular organisms with a physiology that is similar to humans so they are difficult to treat

• Diseases include:• Schistosomiasis (caused by the Schistosoma

flatworm)• Trichinosis (caused by the Trichinella spiralis

roundworm)• Guinea worm disease (caused by Dracunculus

medinensis roundworm)

Prions

• New classification of pathogen (last few decades)

• Infectious Proteins

• Diseases include:• Creutzfeldt-Jakob disease (CJD) in humans• Scrapie in sheep• Bovine spongiform encephalopathy (“mad

cow disease”) in cattle