Soilborne Infectious Diseases

Question 1

Describe this Airborne Disease: Tetanus

(Causative Agent/Characteristic, Virulence Factors, Tissue/Organs Affected, Mode of Transmission, Predisposing Factors, SXS, Diagnosis, Treatment, Preventative Measures)

Answer 1

AKA/Causative Agent/Characteristc

• AKA: x
• CA: Clostridium tetani
• Characteristic: Gram-positive, bacilli; endospore-forming, obligate anaerobe, mostly found in deep layers of soil

Virulence Factors

• Potent, Tetanospasmin neurotoxin
  -> Low LD50

Tissue/Organ Affected

• CNS

Reservoir

• x

Mode of Transmission

• Soilborne
  -> Spores in soil = get introduced into deep muscle layer

Predisposing Factors

• Fomites
  -> Direct contact with nail/sharp object

Incubation Period

• x

SXS
Toxemia (Sys Inf):

• Muscle Spasms
  -> Spores germinate and produce neurotoxin in anaerobic conditions (deep muscle) -> target CNS -> block relaxation muscle pathway
• Head, neck, back muscles stiffness/ spasm
• Respiratory muscle spams = death

Diagnosis

• Bases on SXS

Treatment

• ABX
• Antitoxin
  -> Tetanus Immune globulin (TIG)
• Sedation drugs
  -> control muscle spasms

Preventative Measures

• Vaccine:
  -> DTaP
  -> TDap
  -> TD (toxoid)

MISC

• x

Question 2

Describe this Airborne Disease: Gas Gangrene

(AKA/Causative Agent/Characteristic, Virulence Factors, Predisposing Factors, SXS, Diagnosis, Treatment, Misc)

Answer 2

AKA/Causative Agent/Characteristic

• AKA: Clostridial Myonecrosis
• CA: Clostridium perfingens
• Characteristic: Gram-positive, bacilli; endospore-forming, obligate anaerobe, grow in deep tissue wound

Virulence Factors

• α toxin
  -> Moves along tissue/muscle bundles
  -> Soilborne spores = enter ischemic area of body (anaerobic area) = germinate = produce α toxin = vascular/tissue damage

Tissue/Organ Affected

• x

Reservoir

• x

Mode of Transmission

• x

Predisposing Factors

• Ischemia (that has not been reversed)

Incubation Period

• x

SXS

• Severe pain/swelling
  -> pale area -> red -> blackish green
• Gas and fluid-filled blisters

Diagnosis

• Bases on SXS
• Imaging tests
• Culture

Treatment

• HIGH DOSAGE ABX
• Debridement (amputation) or necrotic/dead tissue
• Hyperbaric chamber (deliver O2)

Preventative Measures

• x

MISC

• Progresses quickkly (initial injury -> gas gangrene) = HIGH MORTALITY (20-25%)
• Common cause of death in wars

Question 3

In relation to Gas Gangrene, define Ischemia and Necrosis, and Gangrene.

Note any additional information about Gangrene.

Answer 3

• Ischemia (reversible): BV blockage = BF stops = No blood/O2 to tissue
• Necrosis (irreversible): Death of tissue
  -> Gangrene: Death of tissue because of interrupted blood supply
  -» Several types of Gangrene: Dry, Wet, Gas Gangrene

Question 4

Describe this Airborne Disease: Histoplasmosis

(Causative Agent, Virulence Factors, Reservoir, Mode of Transmission, Predisposing Factors, SXS, Diagnosis, Treatment, Preventative Measures, Misc)

Answer 4

AKA/Causative Agent/Characteristic

• AKA: x
• CA: Histoplasma capsulatum
• Characteristic: x

Virulence Factors

• Dimorphic Fungus
  -> “Di-“ = Yeast, Mold
• Fungal mold spores (soil)
• Yeast-form grows in macrophages (humans)

Tissue/Organ Affected

• x

Reservoir

• 1) Bird/bat dropping (mold)
• 2) Soil

Mode of Transmission

• Acquired by inhalation of fungal mold spores; Airborne conidia

Predisposing Factors

• Bird/chicken handlers
• Caves
• Common in Mississippi/Ohio River Valleys

Incubation Period

• x

SXS
Fungemia (Sys Inf)/ Mostly Asymptomatic:

• Lung Lesions (Similar to TB)
• Mild/subclinical flu-like SXS (resembles TB)

Diagnosis

• Culture lung tissue/sputum sample
• Chest X-Ray

Treatment

• Antifungals/Antimycotic drugs

Preventative Measures

• NO VACCINE

MISC

• Rarely becomes severe disease
• Differentiate (from TB) through tuberculin skin test and acid-fast staining
  -> if negative = Histoplasma

Question 5

Describe this Airborne Disease: Coccidioidomycosis

(AKA/Causative Agent, Virulence Factors, Mode of Transmission, Predisposing Factors, SXS, Diagnosis, Treatment, Preventative Measures)

Answer 5

AKA/Causative Agent/Characteristic

• AKA: Valley Fever/ San Joaquin Fever
• CA: Coccidioides immitis
• Characteristic: x

Virulence Factors

• Dimorphic Fungus
  -> “Di-“ = Yeast, Mold
• Fungal mold spores (soil)
• Complex lifestyle

Tissue/Organ Affected

• x

Reservoir

• x

Mode of Transmission

• Acquired by inhalation of fungal spores, airborne arthroconidia = spherules in tissue = rel. endospores

Predisposing Factors

• (Found in) Desert soils of American Southwest

Incubation Period

• x

SXS
Fungemia (Sys Inf)/ Mostly Asymptomatic:

• Mild/subclinical flu-like SXS (resembles TB)

Diagnosis

• Culture lung tissue/sputum sample
• Chest X-Ray

Treatment

• Antifungals/Antimycotic drugs

Preventative Measures

• NO VACCINE

MISC

• x

Question 6

Describe this Airborne Disease: Hookworm Infection

(Causative Agent/Characteristic, Virulence Factors, Mode of Transmission, Predisposing Factors, SXS, Diagnosis, Treatment, Preventative Measures, Misc)

Answer 6

AKA/Causative Agent/Characteristic

• AKA: x
• CA: Necator americanus, Ancyclostoma duodenale
• Characteristic: K. Animalia Phylum Nematoda = Roundworm, Hooked-shaped body, separate sexes specialized mouthparts

Virulence Factors

• Complex lifestyle
  -> Adult attaches to intestinal wall = feeds on blood & tissue
  -> Adults -> eggs -> larvae

Tissue/Organ Affected

• x

Reservoir

• x

Mode of Transmission

• Soilborne (larvae in soil)
  -> Larvae in contaminated soil penetrate bare skin

Predisposing Factors

• Barefoot

Incubation Period

• x

SXS
Large # of Worms:

• Anemia
• Fatigue

Diagnosis

• Look for eggs in stool sample

Treatment

• Antiparasitic/Antihelminth drugs

Preventative Measures

• Wear shoes

MISC

• Infectious stage = penetrating larvae
• Humans poop eggs into soil = become larvae in soil = larvae (in soil) penetrate skin
  -> Larvae in hookworm: exists in soil and human

Question 7

Describe this Airborne Disease: Ascariasis

(Causative Agent/Characteristic, Virulence Factors, Mode of Transmission, Predisposing Factors, SXS, Diagnosis, Treatment, Preventative Measures, Misc)

Answer 7

AKA/Causative Agent/Characteristic

• AKA: x
• CA: Ascaris lumbricoides
• Characteristic: K. Animalia Phylum Nematoda = Roundworm, LARGEST roundworm, separate sexes, specialized mouthparts

Virulence Factors

• Complex lifestyle
  -> Adult attaches to intestinal wall = feeds on blood & tissue
  -> Adults -> eggs -> larvae

Tissue/Organ Affected

• x

Reservoir

• x

Mode of Transmission

• Eggs in contaminated soil are ingested

Predisposing Factors

• Poverty
• Unsanitary conditions

Incubation Period

• x

SXS
Mostly asymptomatic/Large # of Worms:

• Intestinal blockage
• Impairs growth in children

Diagnosis

• Look for eggs in stool sample

Treatment

• Antiparasitic/Antihelminth drugs

Preventative Measures

• Do not ingest soil
• Wash hands

MISC

• Infectious stage = ingesting eggs
• Humans poop eggs into soil = human accidentally eats soil (containing eggs) = eggs become larvae in humans
  -> Larvae in ascariasis: exist in human
• Large % (30%) worldwide population is infected