Emerging Infections Test 1 Flashcards
Zika
Flavivirus - Single-stranded RNA Virus - Mosquito Vector - Related to Dengue/Yellow Fever/West Nile - Flavus Latin for Yellow due to the Jaundice it causes.
Mosquito also carries Dengue and Chikungunya
Transmission = Bite, Maternal-fetal, Sex, Blood transfusion, Organ Transplant, Lab Exposure
(Zika RNA has been detected in blood/semen/saliva/female genital secretions/CSF/Amniotic fluid/Breast Milk)
Clin Man = Acute onset: Low-grade fever, pruritic rash (Maculopapular), arthralgia (small joints hands/feet), and conjunctivitis (non-purulent) - Disease usually mild - Dx if 2 or more are present.
Incubation between bite and clin man 2-14 days - Immunity follows infection - Clin manifestations occur in 20-25%
Complications = Fetal Loss, Microcephaly, Guillian-Barre Syndrome (2.4 cases per 100000), Brain ischemia, Myelitis, Meningoencephalitis.
Management = Supportive, NSAIDS (avoided until Dengue ruled out), ASA avoided in children due to risk of Reye Syndrome.
Encouraged to report to CDC
Chikungunya
Endemic to West Africa Vectored by Mosquito (Day feeders) - Name for “Stooped walk” often caused by debilitating arthritis - Africas/Asia/Europe/Islands in Indian and Pacific Oceans/Recently in the US - During the Rainy season
Transmission = Bite, Vertical from mother (rare), Not detected in Breast Milk, No Known cases by Blood or organ transplant.
Clin Man = Abrupt with Fever, Joint pain, and Malaise - Incubation 3-7 Days - Acute phase 7-10 days - 72-97% show symptoms
High grade fever (3-5 days), Polyarthralgia 2-5 days after fever onset commonly involving multiple joints bilaterally/symmetrically (Hands 50-76%, Wrists 29-81%, Ankles 64-73%), Pain is usually intense and disabling
PE = Rash reported in 40-75% of PTs, Macular or Maculopapular, 3 days or later after illness onset, starts on limbs or trunk, pruritis 25-50%, most common findings lymphopenia and thrombocytopenia.
Chikungunya: Complications, Diagnosis, Management, Prevention
Complications = Neurologic (rarely), Death in PTs older than 65, Persistent debilitating and immobilizing arthritis, Respiratory renal and cardiovascular failure, Some PTs have persistent or relapsing disease (18ms-3 yrs)
Dx = Serology (1-7 days rRT-PCR for Chikungunya RNA), ELISA IgM anti-chikungunya antibodies (>8 days), IgM present following 5 days after onset of symptoms and up to 3 months, IgG antibodies begin to appear after 2 weeks and persist for years
Management = Support, NSAIDS, Steroids, Methotrexate, Immune Modulating agents, No Vacc.
Prevention = Minimize Mosquito exposure, Repellants, Bed nets
Dengue
RNA Flavivirus (DENV 1-4) - 47 Strains - Mosquito-Borne - Dengue w/out warning signs, Dengue w/ warning signs, Severe Dengue - Late Summer to early Fall - Rare in US
Transmission = Bite from mosquito (majority), Organ donation or blood transfusion (rare), Maternal-fetal (some evidence), Breast milk (one documented case).
Si/Sx = Mild: NV, Rash, HA/Eye pain, Muscle ache/Joint pain - Severe Symptoms: Abdominal pain, Persistent vomiting, clinical fluid accumulation, Mucosal bleeding (Tourniquet sign), Lethargy/restlessness.
Dengue: Phases of Infection
Febrile = Sudden onset of Fever - accompanied by HA, Rash, Vomiting, Myalgia, arthralgia - Lasts 3 to 7 days,
Febrile PE = Conjunctival injection (red eyes), Pharyngeal erythema, LAD, hepatomegaly, facial puffiness, petechiae - May see Hemorrhagic features
Leukopenia/THrombocytopenia/elevated Liver enzymes
Critical = Systemic vascular leak syndrome: plasma leak, bleeding, shock, organ failure - Days 3-7 and last 24-48 hours, US (Sonogram) for fluid - Moderate to severe thrombocytopenia
Convalescent = Plasma Leakage and haemorrhage resolve, vitals stabilize - Lats 2-4 days = additional rash may appear - profound fatigue that may take days to weeks to recover.
Dengue: Diagnosis, Management, Prevention
Dx = Serum, Nucleic acid amplification test (NAAT) to detect Viral genome - Dengue specific IgM and neutralizing antibodies develop toward the end of the first week - Dengue MAC-ELISA (IgM antibody capture enzyme-linked immunosorbent ASSay) qualitative - PRNT (Plaque Reduction Neutralization Test) Measure titre can be used to identify specific serotype if needed
Management = Support - Fever management (APAP, no NSAIDS) - Bleeding management/blood replacement - Plasma Leakage Volume replacement - Shock Tx
Prevention = Mosquito control, Vaccination, Dengvaxia (licensed outside the US for dengue seropositive or Hx of Dengue), Limit travel, and Improve community participation
Comparison of Zika - Dengue - Chikungunya
Eastern Equine Encephalitis (EEE)
Transmitted via Mosquito - Few cases a Year - MA/FL/NY/NC - Freshwater swampy area, Atlantic and Gulf coast - 30% die, survivors have neuro problems - Incubation 4-10 days
Clin Man = Sudden onset, Fever, HA, N/V, 2% adults and 6% children develop Encephalitis, Once Nero Sx begin conditions deteriorate rapidly, 90% become comatose, Seizures/focal neuro signs (specific area)/Nerve palsies develop in 50%
Dx = Leukocytosis, Hyponatremia, CSF (Pleocytosis, elevated protein), MRI/CT abnormalities, Serum of CSF, IgM antibody capture ELISA, Fatal Cases - Histopathology, autopsy tissues
Management = Supportive, No Vacc, Inactivated Vacc for horses
Ebola
Filoviridae (threadlike) RNA virus (resembles Rabies and Measles/mumps) - 5 species (Zaire - most recent, Sudan - 50% fatalities, Tai Forest - contracted by necropsy, Bundibugyo - 30% fatality, Reston - animal resivoir only) - Thru direct contact with infected body fluids - Outbreaks in Sub-Saharan Africa
Transmission = Contact with meat/body fluid - Most contagious right after death - Hands-on medical care/ and body prep most at risk - Most infectious body fluids are vomit/feces/blood - Less infectious early on - Virus can live on surfaces hrs to days - in Immunologically privileged sites (sterile like CSF)
Clin Man = Major Hemorrhage less common - Volume loss from V/D contribute to severe illness - Sudden onset - Incubation 6 to 12 days - Systemic inflammatory response
Ebola: Physical Exam
PE: Fever/Chills/Malaise/Rash (Diffuse maculopapular, may develop day 5-7)/GI ()/Hemorrhage (Not seen in a majority of cases, some degree of bleeding: bloody stool, petechiae, mucosal bleeding)
Early Phase (1-3 days): Fever, Malaise, sx may be vague
GI (3-10 days): N/V/Watery D, abdominal pain
Rash (May develop day 5-7): Diffuse maculopapular
Shock (7-12 days): w/ or w/out Major Hemorrhage
Recovery (7-12 days): resolution of Sx
Convalescence (up to 2 years): Prolonged Sx of arthralgia, weakness, fatigue, insomnia-Uveitis
Few Cases of PTs that developed new symptoms after recovery from initial infection
PTs who survive infection show signs of clinical improvement during the second week of illness
Ebola: Lab Studies, Diagnosis, Management
Studies = Leukopenia, Thrombocytopenia, Hematocrit (may be increases or decreased), Transaminase elevations (ALT and AST due to liver damage), Coagulation abnormalities (PT, PTT, Prolonged and increase in fibrin degradation products DIC, Mostly in severe and fatal cases), Renal abnormalities (Proteinuria and renal insuff), Electrolyte abnormalities (Hyponatremia, Hypokalemia)
Dx = Identify Risk, Nucleic Acid testing -RTPCR - Viral RNA in serum, ReEbov - rapid immunoassay - detects virus antigen (used in field, results in 15 minutes)
Management = Support (care for volume depletion), Aggressive fluid and electrolyte resuscitation (caution), Anti-emetics, Antipyretics, Blood products (FFP, PRBC, platelets), TPN (Total Parenteral Nutrition), Antivirals (nothing approved but mAb114, REGN-EB3 being used compassionate due to eraly promising results)
Ebola: Prognostic, Prevention, Bioterrorism
Younger PT’s have less mortality, Men have slightly higher mortality rate, Diarrhea has higher mortality rate, as Viral Load increases so does mortality.
Prevention = Strict infection control/Use of PPE, Effective comms between Govt and HCP, Use of rVSV-ZEBOV Vacc effective in ring vaccination.
Bioterror = Appearance of multiple PTs w/ similar rapidly progressive illness can be suggestive of bioterror
Bacteremia
Bacteria in blood, may result from dental work, vigorous brushing, Pneumonia/UTI/ENT, colonization of indwelling devices - Sepsis develops in 25-40% of PTs
Etiology = Gram- Bacteria: GU/GI/Decubitus Ulcers, Chronically ill or immune-compromised
Staphylococcal Bacteremia: IV drug use, IV cath, SSTI
Bacteroides Bacteremia: Infections of abdomen and pelvis, particularly female genital tract
Gram +: Infections above the Diaphragm (respiratory)
Bacteremia: Clinical Manifestations, Diagnosis, Treatment
Clin Man = Asymptomatic, Mild Fever. Persistent Fever, Chills, AMS, Hypotension, Tachypnea, Focal Symptoms
Dx = Blood cultures (Be aware up to 50% of positive blood cultures can be contaminated w/ Coagulace negative strep/Corynebacterium/Viridans
Management = Appropriate antibiotics, Dependent on Cause, Prophylaxis
Sepsis
Dysregulated inflammatory response to infection that can lead to organ dysfunction and death - 4 clinical phenotypes: alpha (lowest does of vasopressor - 5% mortality), beta (older, chronic illness, renal dysfunction - 13%), delta (inflammation and pulmonary dysfunction - 24%), gamma (liver dysfunction and septic shock - 40%)
Epidemiology = Gram + bacteria most frequently identified, approx 50% of cases not identified
Sepsis continuum = Infection -> Bacteremia -> Sepsis -> Septic shock -> MODS -> Death
SIRS = Systemic inflammatory response syndrome (SIRS) is clinically recognized by the presence of TWO or MORE of the following: Fever >38 or <36 C, HR >90 BPM, RR>20 BPM or PaCO2 <32 mmHg, WBC >12000 cells/mm3, <4000 cells/mm3 or >10% immature (band) forms
