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