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Exam 4-Diseases

Terms in this set (69)

Causative agent: Usually herpes simplex virus type 2 (type 1 is cold sores, but the two are close cousins); herpes simplex 1 can also be responsible. Herpes viruses are enveloped and contain double stranded DNA. 1 week incubation period

Signs & Symptoms: Itching, burning pain at the site of infection, painful urination, tiny blisters with underlying redness (look like cold sores in the wrong spot). The blisters break, leaving a painful superficial ulcer, which heals without scarring. Recurrences are common.

Pathogenesis: Lysis of infected epithelial cells results in fluid-filled blisters containing infectious virions. Vesicles burst, causing a painful ulcer. The acute infection is controlled by immune defenses; genome persists within nerve cells in a non-infectious form beyond the reach of immune diseases. Replication of infectious virions can occur and cause recurrent symptoms in the area supplied by the nerve. Newborn babies can contract fatal generalized herpes infection if their mother has a primary infection at the time of delivery.

Epidemiology: NO ANIMAL RESERVOIRS; HUMANS ONLY Transmission by sexual intercourse, oral-genital contact. Transmission risk greatest first few days of active disease. Transmission can occur in the absence of symptoms. Herpes simplex increases the risk of contracting HIV.

Treatment and Prevention: No cure. Medications help prevent recurrences, shorten duration of symptoms. Prevention: abstinence, monogamy, and correct use of condoms help to prevent transmission.
Causative agent: Clostridium botulinum, an anaerobic, Gram-positive, spore-forming, rod-shaoed bacterium. STRICTLY ANAEROBIC

Signs & Symptoms: Blurred or double vision, weakness, nausea, vomiting, diarrhea; generalized paralysis and respiratory insufficiency. 12-36 hour incubation period.

Pathogenesis: C. botulinum endospores germinate in food and release neurotoxin. Toxin is ingested, absorbed, and is carried by the bloodstream to motor nerves; toxin acts by blocking the transmission of nerve signals to the muscles, producing paralysis; C. botulinum can also colonize intestines and cause generalized weakness or paralysis. Can infect host via improperly canned food; very hard to kill and is the result of a swelled can. Likes sugar, acid, and is HEAT RESISTANT.

Epidemiology: Ingestion of toxin produced by vegetative C. botulinum cells growing in a food, often an improperly processed home-canned, low-acid food. Endospores widespread in soil, aquatic sediments, and dust. Organisms can colonize the intestines of adults and infants with deficiencies in normal microbiota, and wounds containing dirt and dead tissue, including those caused by injected drug-abuse.

Treatment & Prevention: Treatment: Enemas and stomach washing to remove toxin, cleaning infected wounds of dirt and dead tissue, IV administration of antitoxin, and artificial respiration (bacteria destroy the nerves which control the lungs). Education in proper home-canning methods; heating food to boiling for 15 minutes just prior to serving.

**Injected into face to purposely damage nerves (Botox)
= kills nerves of forehead to make muscles relax to prevent wrinkles; however, the bacteria circulates in the bloodstream and is a very potent neurotoxin. VERY DANGEROUS!
Causative agent: Human Immunodeficiency Virus (HIV)

Signs & Symptoms: Over 50% develop fever, sore throat, head and muscle aches, rash and enlarged lymph nodes early in infection. After an asymptomatic period, symptoms result from immunodeficiency and include unusual malignant tumors, pneumonia, meningoencephalitis, diarrhea, etc. (ARC symptoms; mark the onset of AIDS).

Pathogenesis: HIV infects various body cells, notably those of the immune system (CD4 + T-cells & antigen-presenting cells). T-cells are killed, with declining numbers until the immune system cannot resist normal issues. Nails the T-helper cells, causing the antibodies and Tc cells to go; no humoral/adaptive immune system.

Epidemiology: Transmission routes: sexual contact, transfer of blood or blood products, mother to child around childbirth. Can be transmitted via breast milk, and possibly oral-genital contact.

Treatment: HAART Therapy, which delays progression of the disease to AIDS. HAARRT is NOT a cue and is too expensive for most of the world's patients. No vaccine yet available. Medications can prevent many of the infections that complicated HIV disease. Anti-HIV meds and C-sections can decrease mother-newborn transmission. Prevention: sex education, needle exchange, condoms.

SOME STDS ENHANCE HIV TRANSMISSION; predominantly found in heterosexuals, but percentage wise, is it said to be transferred most through homosexual men and the least through lesbians. Circumcision also reduces the potential for HIV significantly.

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