Diseases - Unit 2

Giardiasis etiological agent

Giardia lamblia: flagellated protozoan

Giardiasis resevoir

contaminated water & infected mammals

Giardiasis transmission

fecal oral route

Giardiasis pathogenicity

adhesive disk (intestinal wall) feeds on mucus

Giardiasis symptoms

diarrhea (copious, frothy), weight loss, flatulence (sulfurous)

Giardiasis diagnosis

fecal sample under microscope and string test

Giardiasis treatment

oral medication

Giardiasis prevention

handwashing and avoid contaminated water

Giardiasis control

water treatment (cysts are resistant to chlorine/iodine), boil/filter the water

Toxoplasmosis etiologic agent

Toxoplasma gondii: nonmotile protozoa

Toxoplasmosis resevoir

domestic cat (definitive host), other animals (intermediate host)

Toxoplasmosis transmission

ingest cat fecal matter, eating undercooked meat or unwashed produce

Toxoplasmosis pathogenesis

spreads to many tissues (becomes “walled off” by host defenses: persists for years)

Toxoplasmosis symptoms

swollen lymph nodes

Toxoplasmosis pregnant symptoms

cause miscarriage, birth defects (cognitive, vision loss, seizures)

Toxoplasmosis immunocompromised symptoms

reactivation of organism → encephalitis or death

Toxoplasmosis diagnosis

blood test

Toxoplasmosis treatment

none for congenital cases, meds for infected persons

Toxoplasmosis prevention

avoid raw meat and litter boxes

Toxoplasmosis in cats

most asymptomatic, treat with antibiotics, if + test, cat is immune and noninfectious

Ringworm etiologic agent

dermatophytes (several species of fungi)

Ringworm reservoir

common in animals, infected people

Ringworm transmission

contact with contaminated objects (fomites)

Ringworm pathogenesis

minor scrapes contaminated with fungi, superficial

Ringworm symptoms

red, scaly, itchy patches; bald spots; thick nails

Ringworm diagnosis

Skin appearance, skin scrapings

Ringworm treatment

topical antifungal ointment, oral medication for widespread/nails

Ringworm prevention

avoid contaminated objects

Blood fluke

schistosomiasis or bilharzia

Blood fluke etiologic agent

Schistosoma sp. (split body)

Blood fluke definitive host

human

Blood fluke intermediate host

snail

Blood fluke reservoir

infected snails

Blood fluke transmission

free-swimming form in water penetrates skin

Blood fluke pathogenesis

some eggs lodge in tissue

Blood fluke symptoms

diarrhea/malnutrition, anemia, fever, skin itch, tissue damage (chronic)

Blood fluke diagnosis

skin lesions, eggs in feces/urine, blood test

Blood fluke treatment

oral medication (effective in 1-2 days)

Blood fluke prevention

avoid contaminated water

Blood fluke control

sanitation, eliminate host snail

Beef Tapeworm etiologic agent

Taenia saginata

Beef Tapeworm reservoir

definitive host: humans, intermediate host: cattle

Beef Tapeworm transmission

eating undercooked beef (measly)

Beef Tapeworm pathogenesis

ingest cysticercus (larva)

Beef Tapeworm symptoms

malnutrition, usually asymptomatic

Beef Tapeworm diagnosis

proglottids in feces

Beef Tapeworm treatment

oral medication

Beef Tapeworm prevention

cook beef

Beef Tapeworm control

sanitation (irrigation to clean water and fertilizer to eliminate feces)

Ascariasis etiologic agent

Ascaris lumbricoides

Ascariasis reservoir

eggs in soil (human feces)

Ascariasis transmission

ingest eggs (food or water)

Ascariasis pathogenesis

larva in lungs can cause damage, adults in intestine can cause malnutrition, migrating adults can emerge from body openings (nasal, navel)

Ascariasis symptoms

malnutrition

Ascariasis diagnosis

feces for eggs or worms

Ascariasis treatment

oral medication

Ascariasis prevention/control

sanitation

Filariasis etiologic agent

Wuchereria bancrofti

Filariasis reservoir

infected humans

Filariasis transmission

mosquito vector

Filariasis pathogenesis

adult worms block lymph vessels, fluid accumulates, affects immune system

Filariasis diagnosis

blood smear — microfilariae

Filariasis medication

medication, pressure bandages & elevate affected limbs, skin care (clean & hydrate), surgery for hydrocele

Filariasis prevention

mosquito control

Filariasis control

treat all infected persons (meds mostly kill larvae — little effect on adults)

Anthrax etiologic agent

Bacillus anthracis (gram-positive rod, endospores)

Anthrax reservoir

soil, disease of cattle

Anthrax transmission

zoonosis, occupational exposure (contact with animals; handling wool, hides, and meat)

Anthrax pathogenesis

bacteria produce exotoxins (causing edema (swelling), tissues destruction and bleeding; kills macrophages (phagocytic WBC’s))

Anthrax cutaneous form

spores enter skin wound → germinate

Anthrax respiratory form

inhale spores, bacteria → bloodstream (septicemia)

Anthrax intestinal form

ingest spores (contaminated meat), damage intestinal cells

Anthrax cutaneous symptoms

black scab, localized, mortality rate: 10-20%

Anthrax respiratory symptoms

early: fever, cough (2-3 days — septicemia) 100% mortality

Anthrax intestinal symptoms

nausea, bloody diarrhea, ulcerative lesions along GI tract (50% mortality rate)

Anthrax diagnosis

isolate organism from clinical specimen, blood tests

Anthrax treatment

antibiotics (if caught early enough)

Anthrax prevention

vaccine (high risk groups), vaccine for livestock, antibiotics — if suspect exposure

Pneumonia etiologic agent

pneumococcal pneumonia

Pneumococcal Pneumonia etiologic agent

Streptococcus pneumoniae (pneumococcus) gram-positive diplococcus, capsule

Pneumococcal Pneumonia reservoir

healthy human carriers

Pneumococcal Pneumonia transmission

respiratory droplets (most susceptible: elderly, infant, immunocompromised)

Pneumococcal Pneumonia pathogenesis

bacteria evade phagocytes (capsule)

Pneumococcal Pneumonia symptoms

early: mild resp.; high fever, chills, chest pain, couch, bloody sputum

Pneumococcal Pneumonia diagnosis

obtain sputum sample (vs. salivia)

Pneumococcal Pneumonia diagnosis

gram stain sputum: G+ diplococci and confirmatory tests

Pneumococcal Pneumonia treatment

antibiotics (increase in drug resistant strains)

Pneumococcal Pneumonia prevention

vaccine (for elderly) “pneumovax”

Influenza etiologic agent

Influenzavirus

Influenzavirus characteristics

s.s. RNA, enveloped, spikes (H and N)

Influenza A

many subtypes (named by H & N), may cause pandemics (worldwide epidemic), in humans, birds, swine and other vertebrates

Influenza B

humans only, limited epidemics

Influenza C

in humans, rarely a diagnosed problem

Influenza reservoir

infected humans

Influenza Transmission

aerosol droplets

Influenza pathogenesis

first invades resp. epithelial cells (URT), destroys mucus cells & ciliated cells

Influenza symptoms

fever, chills, headache, malaise, muscle soreness, cough, runny nose, sore throat,

Influenza diagnosis

clinical symptoms, swab sample (nasal > throat) rapid test

Influenza treatment

antiviral drugs (lessen symptoms is given promptly (24H))

Influenza prevention

vaccine (killed virus (injection), (live virus: weakened (nasal spray)