Biological Disaster
Biological disaster -------------------- ( BDLS & ADLS)
Factors that compose the "chain of infection" 1. Infectious agent - the greater virulence,invassiveness & pathogenicity --> the greater possibility organism will cause infection
2. Reservoirs - the infectious agent normally lives & multiply , can reproduce itself & transmitted to susceptible host
3. Portal of exit - biological agent leave the reservoir
4. Mode of transmission - mechanism which infectious agent is spread - can be airborne,droplet , direct & indirect physical contact, fecal oral transmission , vector mediated transmission
5. Portal of entry - infectious agent enter host through skin,mucous membrane, lung. GIT, genito urinary , placenta , invasive procedure
6. Susceptible host - influence by factors: 1, hod defense characteristic 2. Medical condition immunocompramised 3. Malnutrition 4. Pregnancy 5. Age 6. Increase exposure risk 7. Behavior factors
Biological disaster --------------------- Epidemic: - illness that occur in higher number that expected within a country & region.
Pandemic: - worldwide epidermic disease - 3 condition: 1. New disease emerges to a population has little or no immunity. 2. Disease is infectious for humans 3. Disease spreads easily among humans
Bioterrorism Criminal act that causes illness, both law enforcement & public health authorities have responsibility to responds .
Intention use of biological agent to harm human or living organism. - inexpensive - easy to produce - easy to disguised - difficult to defend
Potential BT threats ---------------------- Category A: high priority agents - easily disseminated - high mortality - causes public panic - require public health for special action
Eg antarax,botulism,plaque,small pox & tularemia, viral haemorrhagic fevers
Category B: second priority agents - moderate easy to disseminate - moderate morbidity & low mortality - require enhancement of CDC
Eg brucelosis Clostridium perfrongens E. coli Meliodosis Q fever Viral encephalitis
Category C: third priority - easily available - easily produced or disseminated - potential for high morbidity & mortality Eg Nipah virus, SARS
Situational awareness & detection ---------------------------------------- - high index of suspicious - usually multiple report - simultaneously outbreak of different diseases in same locale - large number of casualties in hours to days
Clue for bioterrorism attack -------------------------------- 1. Increase in unexplained deaths 2. Unusual age distribution of patient - severe illness 20-50 years
3. Unusual seasonality 4. Unusual manusfestation of disease or occurrence of animal die off - antarax: inhalation
Clinical decision making ---------------------------- Characteristic clinical symptoms of selected potential BT agents
1. CXR: Widening mediastinum - anthrax
2. Symmetrical flaccid paralysis - botulism
3. Hemoptypsis - pneumonic plaque
4. Pox like rash - small pox
5. Diarrhoea - cholera - shigelosis
Transmission based infection control ------------------------------------------- (I) Droplet precaution ------------------------ - transmitted by large particle droplet >5um - through cough, sneeze, talk or resp care procedure.
Rx 1. 3 feet away 2, surgical mask or respiratory care procedure
(II) contact precaution -------------------------- - transmitted by direct contact with patient or indirect contact with potentially contaminated surfaces
Rx Wear gloves Gown Remove gown before enter Wash hand
(iIi) Airborne precaution ---------------------------- - limit transmission airborne droplet <5um of evaporated droplet containing microorganism that remain suspended in air for long time or dust particles.
Rx N95 Powered air purifying respirators m Negative pressure room with minimum six air exchanges per hour - exhaust direct outside or high efficient particulate air filtration
If source unknown: Contact precaution & N95 or better respiratory
Triage -------- Goal - prevent 2' transmission through implementation non medical strategy
Triage model SEiRV - Susceptible: person not yet exposed but susceptible
- exposed: susceptible & have in contact with infected person, they maybe infected but not contagious
- infectious: symptomatic & contagious
- removed: no longer transmit disease as they survived or died
- vaccinated : prophylactic medication intervention to protect them from infection
Rx Self protective measures Designated evacuation areas ABCs
Clinical assessment & diagnosis ------------------------------------ Fbc ABG Nasal swab for culture & pcr Blood for bacterial culture & pcr Serum for serological studies Sputum for c&s Blood & urine Tox Throat swab for viral culture, Pcr & enzyme linked immunosorbent assay Environment samples
Theurapeutic intervention Established diagnosis Prompt therapy Eg antarax & plaque / treatment within 24H ( longer - grim prognosis)
Biological agent - specific issues ( I) Anthrax ------------- Causative agent: bacillus anthracis
Site of infection : 1. Cutaneous 2. Inhalation 3. GIT
Incubation period: 1-7 days ( as long as 12/7)
Presentation Small itchy papule or vesicles 2nd day : ulcer Usually on exposed area of body Non render swelling around ulcer Small vesicles may surround ulcer Then black scab or ESCAR x 2/52 80-90% resolves LN + Fever +
Inhalation antarax Incubation: 2-43/7
Presentation *** classical : fever & respiratory distress + shock + widening mediastinum
Flu like illness - fever - fatique - cough - sob - headache - anorexia
Then Sudden increase in fever Respiratory distress Diaphoresis Shock
CXR Widening mediastinum Inflitrates Pleural effusion
GI anatarx Ingestion contaminated meat Nausea Vomiting Bloody diarrhoea
Ix Blood culture - gram positive bacilli
Gram stain Sputum CXR: widening mediastinum
Rx IV ciprofloxacin 400mg bd Or IV doxycycline 100mg bd
Standard barrier precaution only No need airborne precaution
Mneumonic: AB CD ( Anthrax bacillus cipro doxy )
Botulism Causative: toxin by C.botulinum One of the most poisonous substance known
Clinical features Onset: 12-36Hv
1. Bulbar palsy 2. Blepharoptosis 3. Bluring vision 4. Dry mouth 5. Difficulty speaking 6. Trouble swallowing
( descending pattern paralysis) " descending type of paralysis"
No fever Not confused Not obtunded Rapid onset Severity depends on amount toxin absorbed
7. Descending symmetrical skeletal muscle paralysis 8. Respiratory muscle paralysis
Diagnosis " clinical presentation" Confirmatory : blood toxin assay
Treatment ----------- Supportive - intensive care + close monitoring respiratory failure & feeding
May take 1-3/12 for the toxin to resolved. Hence; need ventilatiry support if intubated.
Antitoxin - only stop the progression paralysis but will not reverse the existing paralysis.
No prophylaxis
Standard precaution for infectious control. - no person to person transmission
Pneumonia plaque -------------------- Causative agent: Y. pestis
Highly fatal Person to person
Via flea vector
Route; aerosolization ( common)
Clinical features ------------------ Incubation period: 1-6/7
Classical: fever + chills + intense swelling LN in one area.
But if terrorist attack with spray: Fever , cough ---> rapid pneumonia
1. Abrupt onset high fever 2. Chills 3. Malaise 4. SOB 5. Cough with bloody sputum 6. Sepsis 7. Nausea 8. Vomiting 9. Diarrhoea 10. Severe rapidly progressive pneumonia
Diagnosis CXR: pathchy infiltrates Culture blood & sputum Gram stain : safety pun bipolar staining
Rx IM Streptomycin iM /IV gentamicin
Pregnant: gentamicin preferred
Prophylaxis Doxycycline Or Ciprofloxacin
Infectious control: Droplet precaution for 48H - must be 3 feet away
Mneumonic: PSG Department Plaque streptomycin gentamicin droplet precaution
SARS ------- Causative agent ------------------- SARS associated coronavirus
Clinical features ----------------- IP: 2-7 days
1. Flu like prodromal 2. Fever with chills & rigors 3. Headache 4. Muscle aches 5. May hv diarrhoea
Day 3-7: Cough SOB
Diagnosis
Probable SARS: Severe respiratory illness Unknown etiology Epidemiology of exposure Lab criteria used to confirm
Suspected SARS: Moderate respiratory illness Unknown etiology Epidemiology for exposure Lab criteria to confirm
Moderate respiratory illness - temp > 100.4'c - respiratory findings 1. Cough 2. Sob 3. Hypoxia
Severe respiratory illness - moderate respiratory illness + one findings as below: 1. X-ray: pneumonia 2. Respiratory distress syndrome 3. Autopsy: pneumonia or RDS w/o cause
Epidemiology - exposure to SARS in travel within 10/7 to area with current,documented or suspected SARS.
Treatment No proven Tx Antibiotic to cover CAP & atypical pathogens
Prophylaxis No known
Infection control - standard precaution ( hand wash) - contact precaution ( gown & gloves) - airborne precaution ( -ve pressure room & N95) - eye protection
Smallpox ----------- Mortality rate 30%
Clinical features IP: 7-17 days
Prodromal ( more severe than chicken pox) ( look sick before rashes appear) - lasting 2-3/7 - fever - myalgia - prostration - nausea - vomiting - delirium
Rash ( all same stages of maturity) ( more rounded) ( more in face & extremities while chicken pox more in trunk ) ( chicken pox less on palm & soles) ( start periphery then go centrally) " outside to inside" " all same stage"
- start on face & extremities including palm & soles Then spread to trunk ( macular --> papular--> vesicles--> pustules ) - form,deep & umbilicated - rash scan over 1-2/52 resulting in scars
Diagnosis 1. Clinical recognition 2. History 3. Confirmatory test in CDC
Treatment Vaccination small pox - very effective if within 3/7 exposure
Supportive care Daily eye rinsing Adequate hydration & nutrition Start penicillase resistant antibiotic if : 1. Secondary infected 2. Bacterial endangers the eyes 3. Eruption very dense & widespread
Specific therapy No specific therapy If corneal lesions: topical isoxuridine
Cidofovir
Infection control ------------------ Airborne & contact precaution Treated in negative pressure room
Tularemia ------------- Agent Francisella tularensis
Spread: Ticks or biting flies Direct bite by rabbits
Clinical features ------------------ Classical; fever + tender papule --> ulcer with eschar + tender LN
If terrorist by spray; fever + shock + pneumonia
IP: 3-5/7
1. Acute febrile illness with prostration 2. Conjunctivitis or skin ulcer with regional adenopathy 3. X-ray: pneumonia (80%)
Diagnosis ----------- Blood C&S Gram -ve coccobacillus
Treatment ------------ IV streptomycin + gentamicin
Alternative: Doxycycline Ciprofloxacin Chromphenicol
Prophylaxis Doxycycline Ciprofloxacin X 14/7
Infection control ------------------ - not spread from person to person - standard precaution. - no need any isolation - notification immediately
Viral haemorrhaguc fever ----------------------------- Examples 1. Filovirus Ebola Marburg
2. Arenavirus Lassa Machupo
Transmitted Infected animal or arthopods
Mortality rate Ebola: 90%
Clinical features ------------------- IP: 2-21/7
Presentation: 1. Non specific prodromal 2. Hypotension 3. Relative bradycardia 4. Rapid breathing 5. Conjunctivitis 6. Pharyngitis 7. Generalized bleeding problems - mucous membrane haemorrhage - shock - hematemesis - hemoptypsis - hematochezia
2 haemorrhagic symptoms in severely ill patient with t >101F <3/52 with no other alternate diagnosis
Diagnosis ----------- High index suspicious Thrombocytopenia Leukopenia aST raised Lab detection of antigen & antibodies
Treatment ------------ Supportive Ribavirin
Prophylaxis ---------------- None
Isolation ----------- Contagious after contact blood & bodily fluids
Liquid impervious protective coverings ( leg & shoe coverings) + double gloves
N95 or better
Face shield Googles
Negative pressure room
Clinical consideration for pediatric casualties ---------------------------------------------------- More vulnerable - breathes more per min than adults - skin thinner & larger surface area ratio
- small fluid reserve - some agents have shorter incubation period in children - present with different symptoms - preventive & theurapeutic regime not studiesbin infant & children