Exam 2 Flashcards
Direct & Indirect Effects of Bioterrorism
o Economic
o Social & emotional impacts: Fear & panic
o Environmental consequences
o Malnutrition, sanitation, infectious disease
o Direct effects of biological weapons shrink in proportion to indirect effects
Aspects of a “Good” Bio Weapon
o Stable o Short incubation o Low infectivity dose o High morbidity o Severe disease
Bioterrorism Category A
o Highest priority agents
o Risk to National Security, rarely seen in US
o Easily disseminated
o Rapidly spread person to person
o High mortality, significant public health impact
o Cause public panic and social disruptions
o Require special action for public health preparedness
Diseases in Category A
- Foot and mouth disease
- Classical swine fever
- Newcastle disease
- Vesicular stomatitis
- Highly pathogenic avian influenza
- Anthrax
- Botulism
- Plague
- Smallpox
- Tularemia
- Viral hemorrhagic fever
Bioterrorism Category B
o Second highest priority agents o Moderately easy to disseminate o Moderate morbidity rates o Low mortality rates o Requires enhancements for diagnostic capacity and disease surveillance
Diseases in Category B
- Brucellosis
- Epsilon toxins of Clostridium perf
- Glanders
- Psittacosis
- Q fever
- Ricin toxin
- Typhus
- Viral encephalitis
- Staph enterotoxin B
- Water & food threats
Bioterrorism Category C
o Third highest priority
o Emerging pathogens that could be engineered for mass dissemination
o Ease of availability, production, and spread
o Potentially high morbidity and mortality
Diseases in Category C
- Nipah virus,
- AI
- Hantaviruses
When to Suspect Bioterrorism
o Clusters of disease or deaths
o Disease in unpredicted species, season, or geographic region
o Unusually high morbidity &/or mortality
o Unusual presentation or route of transmission (Aerosol)
o Endemic disease with increased incidence
o Single case of disease from uncommon agent
Giardia Basics
- Many species
- Protozoan
- Humans: Giardia duodenalis (G. intestinalis, G. lamblia)
- Dogs: Giardia canis
- No environmental replication, cysts persist
- Dogs & cats carry A & B that can infect humans
Giardia Transmission
o cysts shed in feces ->
o Cysts can survive for months in cold water ->
o Ingestion of cysts in contaminated water or food
–>
o Human-to-human transmission
– Primary source of human infections
o Animal-to-human transmission
– Only if assemblages A&B
Giardia in Humans; basics & acute/chronic symptoms
o Most common intestinal parasite in humans o 1-3wk incubation o late summer o Asymptomatic carriers o Re-infection common
Acute Symptoms
• Cramps, nausea, V/D, gas, dehydration
Chronic Symptoms
• Weight loss & malnutrition
Giardia Diagnosis in Dogs & Cats
o Do 3 fecal samples due to intermittent shedding
o Direct fecal smear
o Zinc sulfate fecal
floatation
o Fecal IFA & ELISA- SNAP test
o PCR- only method to determine Assemblage (Rarely done)
ELISA SNAP Giardia Test
o Warm to room temp
o Check results @ correct time
Giardia Treatment in Humans Vs Animals
Humans:
• Metronidazole,
• Tinidazole
• nitazoxanide
Animals:
• Metronidazole,
• fenbendazole,
• albendazole
Giardia Prevention
o Good hygiene o Avoid potentially contaminated water o Prevent contact w/ feces o Diagnose & treat infections o Giardia vx for dogs/cats resists oocyte shedding (discontinued)
Leptospirosis Basics & Transmission
- Spirochete Leptospira
- Gram (-)
- Greater than 200 serovars
- Does not replicate outside of the host
- maintained in environmental water sources, mud, and wet soil for extended periods
- Global distribution
Transmission o Urine, blood, tissue, contaminated soil/water into abraided skin or mucosal surface o In utero o Horizontally through semen o Lab transmission o Floods
Leptospirosis Clinical Signs
o Hepatic dz o Red water o Renal failure o Abortion o Mastitis o Uveitis in horses
Leptospirosis Diagnosis & Treatment
Diagnosis o Clin Path for renal and hepatic disease o Kidney biopsy o Serology o FA & IHC of abortions or necropsy o PCR of urine & water o Culture (very slow weeks)
Treatment
o doxycycline,
o penicillin,
o oxytetracycline
Leptospirosis Prevention
o Water sanitation
o Hygiene: protective clothing, hand- washing
Vaccination
• Swine, Cattle, Dogs
• Not cross protective
• Controversial to recommend
Cattle Producer Leptospirosis Control Recommendations
o Vx for several serovars
o Vx calves 3-6mo to avoid maternal Ab
o Boost bi-annually
Basics of Tularemia
o Francisella tularensis o Gram negative, aerobic coccobacillus o Hardy, non-spore-forming o Category A bioterrorism agent o North Americ & Eurasia o Survives well in H2O, moist soil, decaying carcasses
2 Maintenance Cycles of Tularemia & Reservoir/Hosts
Maintenance Cycles
o Rabbits/hares/ticks
OR
o Voles, mice, squirrels, muskrat/direct contact or contaminated aquatic environment
o Reservoir
Lagomorph, wild rodents, ticks (transovarian)
o Hosts
• MANY species
Transmission of Tularemia
o Biological vector: Dermacentor & Amblyomma ticks
o Mechanical vector: deer flies, mosquitoes
o Directcontact: bites, secretions
o Inhalation
during lawn mewing, shearing rabbits
o Ingestion of infected animals, contaminated food
o Lab BL3 to culture
o No person-to person transmission
Why is Tularemia Used as a Bioterrorism Weapon
o Easy to acquire o Stable in the environment o Intentional contamination of food and/or water o Aerosolization o Multiple species infected
4 Presentations of Tularemia in Humans
Ulceroglandular infection
• An ulcerative skin lesion with lymphadenopathy
Pharyngeal infection:
• via ingestion
• cervical, submandibular, mediastinal lymphadenitis;
• exudative pharyngitis, oral ulcers
Septicemia (typhoidal)
• hepatomegaly, splenomegaly
Pneumonic
• via inhalation
• Radiographic and clinical evidence of pneumonia, pleuritis,
• 60% fatal if not treated
basics & 3 forms of Tularemia in Animals
o Fever, lethargy, anorexia, stiff gait, increased pulse and respiration, coughing, vomiting, diarrhea and pollakiuria
incubation:
• 3-5 days, (1-14 days)
Ulceroglandular form:
• cutaneous ulcers & regional lymphadenopathy
Septicemic form:
• hepatomegaly, icterus, sheep
Pneumonic form:
• rare
Tularemia Diagnosis, Treatment, Control
Diagnosis o Serology: 4-fold change o Culture of blood, aspirate, exudate or biopsy o Direct FA o PCR
Treatment
o Doxycycline, tetracyclines, chloramphenica, ciprofloxacin
o Resistant to Beta-lactams: Penicillin & cephalosporins
Control o Prevent pets from hunting rodents/rabbits o Tick control o PPE around infected animals o Food hygiene o No Vx
What is an Emerging Dz
o Appearance in new host o Changes in pathogen’s underlying epidemiology o Evolved strains o Recent & 1st entry into a host o Increased incidence
Factors of Pathogens Contributing to Emergence of Dz
Antimicrobial resistance
• Transformation
• Transduction
• Conjugation
Genetic adaptation & change • Nucleotide substitution • Natural selection • Recombination • Reassortment
Factors of Humans Contributing to Emergence of Dz
Human demographic changes • Increased human contact • Increased contact with wildlife • Intensification of agriculture • Population displacement
Human behavior
• Sexual practices, IV drug use: HIV
• Intent to harm: Anthrax, Botulism
• Domestication of animals: Toxoplasma
Human susceptibility to infection
• Immunocompromising conditions: HIV, cancer
• Nosocomial infections: SARS, Ebola, MRSA, MERS-CoV
• Transplants/infusions: HIV, Cryptococcus neoformans, Baboon cytomegalovirus
• Implants/surgical instruments: vCJD, fungal meningitis in contaminated steroid injections
What does R sub 0 mean in Emerging Dz
o <1 = limited spread
o 1 = endemic
o >1 = epidemic
Basics of Plague & Transmission
o Yersinia pestis
o Gram (-) coccobacilli
o Slow growing
o 5-15 human cases annually
Transmission
• Flea bite
• Flea ingestion
• Humans can get it through aerosols from infected cat
• Humans can get from eating infected goat
3 Cycles of Plague
Sylvatic (wild)
• Reservoir = rodents (prairie dog, rabbits, mice, dogs)
• Vector = wild rodent flea
Urban (domestic)
• Reservoir = urban black rat
• Vector = original rat flea – xenopsylla cheopis
Human
• Bubonic plague from contact w/ sylvatic or urban reservoir or arthropod vector bite ->
• Transmit to other humans ->
• Pneumonic plague
