Infectious disease Flashcards
suspected case
- epidemiological exposure
- 2+ sx
probable case
- relevant epidemiological exposure
- no disease sx
- positive IgM
confirmed case
- viral RNA or antigen detected
- IgM antibody
- “tested positive for virus”
what causes zika
- flavivirus
- single strand RNA virus
how is zika transmitted
- mosquitoes
- aedes aegypti and aedes albopictus strands
- day and twilight feeders
- breed in standing water
- can be transmitted sexually, maternal-fetal
- less frequently transmitted through blood transfusions, organ transplant, lab exposure
where did zika originate
uganda in rheusus monkeys
where are the more recent zika outbreaks
- yap island- 2007
- french polyesia- 2013-14
- chile easter island - 2014
- brazil- 2015
- current- americas, caribbean, pacific islands, sub-saharan africa, asia
- pregnant women/ attempting avoid travel below 6500 feet
- cases in US related to travel
what fluids is zika detected in
- blood
- semen
- saliva
- female GU secretions
- amniotic fluid
- breast milk
clinical manifestations of zika
- only in 20% of pts
- mild in those with sx
- low grade fever
- pruritic rash
- arthralgia - small joints
- conjunctivitis
- microcephaly in pregnant females
- dx if 2+ sx
- immunity after infection
what is the incubation period for zika
- 2-14 days
- resolves in 2-7 days
less common sx of zika
- HA
- retro-orbital pain
- myalgia
- n/d
- abd pain
- mucus membrane ulceration
complications of zika
- fetal loss
- microcephaly
- guillian barre syndrome
- brain ischemia
- myelitis
- meningoencephalitis
diagnosis of zika
- serum virus if sx onset < 14 days
- serum IgM if sx onset > 14 days
management of zika
- supportive- rest, hydrate, APAP
- NAIDS avoided until r/o dengue
- ASA avoided in kids- Reye
prevention of zika
- no vaccine
- limit travel to certain areas
- remove standing water
- mosquito repellent
- long sleeves/pants
- environmental control
- protected intercourse
- must report zika cases to CDC
what causes chikungunya
- alphavirus
- single strand RNA
where is chikungunya found
- endemic to west africa
- asia
- europe
- islands in indian and pacific oceans
- americas
- during rainy seasons
- outbreaks have high attack rates
- all US cases d/t travel
how is chikungunya spread
- mosquitos
- aedes aegypti and aedes albopictus
- day feeder mosquitos
- vertical transmission, blood donation, and organ transplant rare causes of transmission
clinical manifestations of chikungunya
- abrupt fever (high grade) and malaise
- polyarthralgia 2-5 days after fever in smaller joints bilaterally
- pain is intense and disabling
- maculopapular rash +/- pruritis
- nonspecific lab changes
what is the incubation period of chikungunya
- 3-7 days
- acute phase lasts 7-10 days
- majority of pts show sx
complications of chikungunya
- death in pts >65 with comorbidities
- persistent debilitating and immobilizing arthritis
- resp, renal, and CV failure
- can be persistent and relapsing up to 3 years
diagnosis of chikungunya
- virus detected 1-7 days
- antibodies detected > 8 days
- IgM present after 5 days onset, persists for 3 mo
- IgG present after 2 weeks, persists for years
management of chikungunya
- supportive
- NSAIDS
- steroids, methotrexate, immune modulating agents for severe arthritis
- no vaccine
prevention of chikungunya
- minimize mosquito exposure
- repellants
- bed nets
what causes dengue virus
- flavivirus
- single strand RNA virus
- four types DENV 1-4 with 46 strains
how is dengue spread
- mosquito
- aedes aegypti and aedes albopictus
- maternal- fetal transmission
- leading cause of death in tropics and subtropics
- death most often in kids
current dengue classifications
- dengue without warning sign
- dengue with warning signs
- severe dengue
where is dengue found
- rio de janeiro
- bolivia
- argenita
- brazil
- peru
- paraguay
- mexico
dengue without warning signs symptoms
- n/v
- rash
- HA
- eye pain
- muscle ache, joint pain
- leukopenia
- positive tourniquet test
dengue with warning signs sx
- abd pain
- persistent vomitting
- fluid accumulation
- mucosal bleeding
- lethargy or restlessness
- hepatosplenomegaly
- increased HCT and decreased platelet
severe dengue sx
- plasma leakage -> shock and fluid accumulation
- respiratory distress
- severe bleeding
- severe organ failure
- impaired consciousness
phases of dengue infection
- febrile
- critical
- convalescent
febrile dengue phase
- high grade fever
- HA
- rash
- vomiting
- myalgia
- arthralgia
- 3-7 days long
- conjunctival injection
- pharyngeal erythema
- hepatomegaly
- facial puffiness
- petichiae
- recover without complications
critical dengue phase
- systemic vascular leak syndrome
- plasma leak
- bleeding
- shock
- organ failure
- days 3-7 and lasts 34-48 hours
- mod- severe thrombocytopenia
convalescent dengue phase
- plasma leak and hemorrhage resolve
- vital signs stabilize
- usually lasts 2-4 days
- rash may appear
- profound fatigue, can take weeks to recover
diagnosis of dengue
- viral antigen in first week
- IgM as early as four days after onset
management of dengue
- supportive
- APAP for fever
- no NSAIDs bc of bleed risk
- bleed management with blood replacement
- volume replacement
- shock tx
dengue prevention
- mosquito control
- vaccination- only for seropos or hx of dengue
- limit travel
- improve community participation
ebola virus cause
- filoviridae
- single strand RNA virus
- resembles rabies, measles, mumps
- has 5 species
how is ebola spread
- direct contact with infected body fluids
what are the ebola species
- zaire
- sudan
- tai forest (ivory coast)
- bundibugyo
- reston- only animal reservoir
where is ebola found
- sub-saharan africa
- guinea
- liberia
- sierra leone
- nigeria
- senegal
- mali
how is ebola spread
- contact with meat or body fluids of infected animals/ humans
- virus can spread even after human/animal dies
- lives on surfaces for hours- days
- survives forever in immunologically privileged sites
what is the most infectious body fluid associated with ebola
- vomit
- feces
- blood
- less infectious in early stages
who is at the greatest risk of ebola
- medical provider
- prep body for burial
ebola clinical symptoms
- fever, chills, malaise (d 1-3)
- rash
- n/v/d abd pain (d 3-10)
- shock (day 7-12)
- hemorrhage not often seen
- convalescence up to two years- arthralgia, weakness, fatigue, insomnia
when do ebola pts start to get better if they survive
during the second week
lab findings for ebola
- leukopenia
- thrombocytopenia
- hematocrit increased or decreased
- increased ALT and AST
- coag abnormalities
- renal abnormalities
- electrolyte abnormalities
diagnosis of ebola
- ID pt risk
- viral RNA in serum
- ReEbov available for rapid dx (15 min)
ebola management
- supportive care
- fluid/ electrolytes
- anti-emetics
- antipyretic
- blood products
- TPN
- antivirals
- compassionate use meds
prognostic factors for ebola
- age- younger has less mortality
- gender- slightly higher mortality in males
- GI- higher rate of mortality with diarrhea
- viral load
ebola prevention
- strict infection control
- proper use of personal protective equipment
- communication btwn government and health care works
- no vaccine
- considered cat A bioterror agent
what makes up the sepsis continuum
infection -> bacteremia -> . sepsis -> septic shock -> MODS -> death
what is the most common cause of bateremia?
- staph aureus
- in community acquired and hospital acquired
what is the most common cause of bacteremia d/t skin and soft tissue infections
stroup a streptococcus
what is a common cause of bacteremia in immuncompromised
pseudomonas
seeding for bacteremia
- respiratory tract
- UTI
- abdominal infection
- ENT
- instrumentation i.e. catheter
- surgery
- prosthesis
clinical signs of bacteremia
- hypotension
- tachycardia
- fever
- chills
- malaise
- SIRS possible
treatment for bacteremia
- empiric PO abx (staph and strep coverage)
sepsis
- life threatening organ dysfunction and infection
- dysregulated host response to infection
septic shock
sepsis with circulatory cellular and metabolic abnormalities
epidemiology of sepsis
- higher in AA males
- greatest during winter
- > 65 is most cases
- GP bacteria
SIRS diagnosis
- two or more of the following:
- temp >38 C or < 36 C
- HR > 90
- RR > 20 or PaCO2 <32 mmHg
- WBC >12,000, <4,000 cells, or >10% immature forms
organ dysfunction assessment in sepsis
- GCS score
- BP
- ventilator support
- renal function
- liver function
- platelets
risk factors for sepsis
- ICU admission
- bacteremia
- advanced age
- immunosuppression
- diabetes and cancer
- community acquired pneumonia
- previous hospitalization
septic shock clinical manifestations
- vasodilatory or distributory shock
- require vasopressors
- cool skin
- cyanosis
- oligouria
- altered mentation
- elevated lactate
multiorgan dysfunction syndrome (MODS)
- progressive organ dysfunction
- severe end of severe illness
- primary or secondary
- no universally accepted criteria for dx
how is lyme disease transmitted?
- tick bite
- mainly deer tick aka black legged ticks (l. scapularis)
what causes lyme disease?
- borrelia burgdorferi
- spirochete
in what stage of life are most ticks in when they transmit lyme disease?
- nymph stage
- adults are larger so are more easily seen/ removed
risk factors for lyme disase
- outdoor occupation
- recreational activities in wooded area
- live in an endemic area like new england
when do deer ticks transmit lyme disease?
- when feeding (look engorged)
- if tick is easily removed or walking on surface it cannot transmit disease
- if attached for > 72 hours likely to transmit disease
what are the three phases of lyme disease
- early localized disease
- early disseminated disease
- late disease
clinical manifestations of early localized lyme disease
- erythema migrans***
- EM usually appears 7-14 days after bite
- nonspecific viral sx
- absence of rash means lyme is likely NOT your dx
common characteristics of erythema migrans
- painless
- erythematous
- circular
- large diameter
- central clearing may develop
symptoms of early disseminated lyme disease
- neurologic or cardiac involvement
- occurs weeks to several months after bite
- multiple EM lesions means disease is disseminated
- uni/bilateral CN palsies (facial common)
symptoms of late lyme disease
- much less common
- months to years after initial infection
- usually arthritis in more than one joint (knees common)
- neurologic subtleties
diagnosis of early lyme disease
- clinical dx
- EM and/or viral symtpoms with hx of exposure is diagnostic
- NO serology
diagnosis of early disseminated or late lyme disease
- hx and PE
- serologic testing as adjunct
when do you perform serology testing on a suspected lyme disease case?
- recent exposure to endemic area AND - risk factor for exposure AND - sx consistent with early disseminated or late disease
who should not get serology testing for lyme disease
- pts with EM rash
- screening of asymptomatic pts living in endemic areas
what serological tests are used for lyme disease
- ELISA then western blot
when do antibodies for lyme appear
- IgM- 1-2 weeks after infection
- IgG- 2-6 weeks after infection
- remain elevated even after treatment and resolution of sx for years
- routine f/u serologic testing NOT recommended
what is the DOC for lyme disease?
- doxycycline
- 100 mg orally twice daily X21 days
- ** cannot be given to kids <8 or pregnant/ lactating women
what are the second line agents for treating lyme disease?
- amoxicillin 500 mg orally 3 times daily X21 days
- cefuroxime 500 mg orally twice daily X 21 days
what is the treatment for early disseminated lyme disease?
- IV antibiotics X 21-28 days
- ceftriaxone
- cefotazime
- penicillin
- caveat- if pt has facial palsy can treat with PO doxyxycline 100 mg twice daily
treatment for late lyme disease
- oral doxycycline or amoxicillin for 1 month
- usually to treat arthritis
can you be infected with lyme more than once?
yes
what is the prophylactic dose for lyme disease?
- doxycycline 200 mg orally as single dose (so take two pills once)
who should be treated prophylactically for lyme?
- tick ID as deer tick
- tick was attached > 36 hrs
- must start within 72 hours of tick removal
- high rate of local infection
- doxycycline not C/I
what causes rocky mountain spotted fever (RMSF)?
- r. rickettsi
- GN bacteria
what is the main issue with RMSF
- bacteria causes increased vascular permeability
- clinical response varies from pt to pt
who is most likely to die from RMSF?
- kids < 4
- adults > 60
how is RMSF transmitted?
- tick bite
- dock tick and rocky mountain wood tick
- bacteria released 6-10 hours after bite
symptoms of RMSF
- usually start 2-14 days after bite
- nonspecific viral sx
- hallmark rash- blanching erythematous rash with macules that become petechial
- rash usually begings on ankles and wrists -> trunk
- rash seen on palms and soles
diagnosis of RMSF
- clinical diagnosis
- serologic testing for confirmation
- skin biopsy before or within 12 hours of abx
- empiric therapy should be started within 5 days of sx onset
what is the DOC for RMSF?
- doxycycline
what causes babesiosis
- babesia protozoa
how is babesiosis transmitted
- tick bite
what is the main concern with babesiosis
- causes RBC lysis
- sx vary but can be fatal
clinical manifestations of babesiosis
- dev within 1-6 weeks of tick bite
- associated with RBC lysis
- fever, malaise, weakness
- splenomegaly and hepatomegaly
who is most at risk for a severe course of babesiosis
- asplenism
- immunocompromised
what are complications associated with babesiosis?
- DIC
- ARDS
- CHF
- renal failure
diagnosis of babesiosis
- blood smear
- PCR
- serology for acute infection (should not be sole diagnostic tool)
what is the DOC for babesiosis?
- atovaquone plus azithromycin
- 7-10 days of treatment
what causes rabies?
- rhabdoviridiae virus
- part of neuotropic viruses
what determines susceptibility to rabies
- bite location
- virus varient
- size of innoculation
- degree of innervation at site of bite
- host immunity and genetics
what disease has the highest case fatality of any infectious disease?
- rabies
- death primarily in developing countries
how is rabies transmitted?
- mainly exposure to saliva from animal bite
types of rabies
- prodrome- nonspecific viral sx
- clinical rabies- either encephalitic or paralytic
- once pt exhibits si/sx, often progresses to death
encephalitic rabies
- most common
- death d/t respiratory and vascular collapse
- hydrophobia and aerophobia
- hyperactivity of facial, back and neck muscles
- autonomic instability
- agitation and combativeness
paralytic rabies
- ascending paralysis
- starts in affected limb then spreads
- little CNS involvement until later in course
- death d/t respiratory muscles failure
diagnosis of rabies
- lab testing of several specimen
- staining of skin biopsies
- virus can be obtained from saliva
- anti-rabies Ab obtained from CSF
- most cases dx postmortem
what occurs around the site of a rabies bite?
- paresthesias
rabies treatment
- mainly focused on prevention
- palliative treatment
- aggressive treatment in ICU
post exposure prophylaxis of rabies
- can seek guidance from local public health authorities about who needs PEP
- should be considered in bat bites/ bat exposure
- can give immunoglobulin as passive immunization and vaccine as active immunization
rabies and travel prophylaxis
- give to people who may be working around rabid animals
- kids who will be living in endemic areas
- people who will be in areas where dog rabies is common
pre-exposure prophylaxis
- give 3 doses of vaccine
- booster may be needed if ongoing risk of rabies
- serologic testing can confirm protective levels
how is malaria transmitted
- mosquito bites
who is most at risk for severe malaria infections?
- young children
- pregnant women
- travelers to endemic regions
- older kids and adults can dev immunity after repeated infections
what causes malaria?
- parasites
- p. falciparum causes severe illness
symptoms of malaria
- cyclic fever***
- nonspecific sx
- anemia
how is malaria diagnosed?
- giemsa stained blood smear
- rapid diagnositc tests available in endemic areas
who requires hospitalization d/t malaria?
- young kids
- immunocompromised
- no acquired immunity
- pts with parasitemia but no sx
what is the DOC for malaria
- chloroquine
- other regimens available for chloroquine resistant strains
