Infectous disease MDTs Flashcards
Person or animal that harbors the infectious agent/disease and can
transmit it to others but does not demonstrate signs of the disease.
Carrier
Exposure to a source of an infection; a person who has been exposed.
Contact does not imply infection; it implies possibility of infection.
Contact
Capable of being transmitted from person to person by contact or
proximity. Does not need or utilize a vector.
Contagious
An organism that harbors a parasitic, mutualistic, or commensalism
guest. The host is the house & the parasite is the freeloader.
Host
An organism that lives on or in a host organism and gets its food from
or at the expense of its host. Three main classes of human parasites are
protozoa, helminths, and ectoparasites.
Parasite
An infectious agent or organism that can produce disease.
Pathogen
Invasion of the body tissues of a host by an infectious agent, regardless if it causes disease or not.
Infection
A pathway into the host that gives an agent access to tissue that will
allow it to multiply or act.
Portal of entry
A population of organisms or the specific environment in which an infectious pathogen naturally lives and reproduces; usually a living host of a certain species.
Reservoir
A pathogen that is transmissible from non-human animals (typically vertebrates) to humans.
Zoonosis
An increase, often sudden, in the number of cases of a disease above what is normally expected in that population and area.
Epidemic
Carries the same definition of epidemic but is often used for a more limited geographic area.
Outbreak
The constant presence of an agent or health condition within a given
geographic area or population.
Endemic
An epidemic occurring over a widespread area (multiple countries or
continents) and usually affecting a substantial proportion of the
population.
Pandemic
Any of a group of viruses that are transmitted between hosts by mosquitoes, ticks, and other arthropods.
Arbovirus
Describes any illness, impairment, degradation of health, chronic, or
age-related disease.
Morbidity
↑ Morbidity = ↓ lifespan & ↑ mortality when infected with any
pathogen.
Time interval from a person being infected to the onset of symptoms of an infectious disease.
Incubation period
Time interval from a person being infected to the time of
infectiousness of an infectious disease.
Latency period
An infection that is nearly or completely asymptomatic. A
subclinically infected person is an asymptomatic carrier of the infection.
Subclinical Infection
A combination of symptoms, characteristic of a disease, or health
condition; sometimes refers to a health condition without a clear cause.
Greek for “concurrence.”
Syndrome
Measure of death in a defined population during a specified time
interval, from a defined cause.
Mortality rate
Transmission occurs when there is no direct human-to-human contact.
Indirect contact (infection):
Transmission occurs between an infected person and a susceptible
person via direct physical contact with blood or body fluids.
Direct contact (infection):
often indicate the “onset of a disease” before more diagnostically specific signs and symptoms
develop.
Prodrome
Three main classes of human parasites
protozoa,
helminths,
ectoparasites.
One-celled organisms that are free-living or
harbors on a host.
Protozoa
Large multicellular organisms visible to the
naked eye in adult stage, that are free-living or harbors on a
host.
Helminths
Ticks, fleas, lice, and mites that burrow
into the skin and remain there for weeks to months. This category broadly including other blood-sucking arthropods such as mosquitos.
Ectoparasites
Primary the Culex mosquito; blood transfusion/organ
donation; mother to child
West Nile Virus
single-stranded RNA virus of the family Flaviviridae
Incubation period of west nile
2 to 6 days usually but 14 max
Symptoms of west nile virus
70-80% of human WNV infections are subclinical or asymptomatic.
An acute systemic febrile illness may be accompanied by:
1) Headache, weakness, myalgia, or arthralgia
2) Gastrointestinal symptoms
3) Transient maculopapular rash
Neuroinvasive WNV
< 1% of infected patients develop neuroinvasive WNV, which typically manifests as meningitis, encephalitis, or acute flaccid paralysis.
Diagnosis test of WNV
ELISA is used to detect IgM antibody.
If CNS symptoms are present, lumbar puncture with CSF
analysis
CBC is not a reliable indicator of disease.
Treatment of WNV
Vigorous supportive measures are the first line management protocol:
Patients with severe meningeal symptoms often require pain
control for headaches, antiemetic therapy and rehydration for
associated nausea & vomiting.
MEDEVAC is warranted if there are signs of encephalitis, meningitis,
or paralysis.
WNV – Prevention
No WNV vaccines are licensed for use in humans.
Community-level mosquito control programs to reduce vector
densities.
Personal protective measures to decrease exposure to infected
mosquitoes
(Screening of blood and organ donors.
Malaria subtypes
P. falciparum, P. vivax, P. ovale, or P. malariae.
The p is for plasmodium
Transmitted Via: Female anopheles mosquito
Incubation period of Malaria
Incubation Period: 7 to 30 days, depending on the species of malaria
infection
Which subtype of malaria skips the liver
P Falciparum
Malaria life cycle
Sporogony Phase - Sexual cycle in Female Anopheles Mosquito:
Exoerythrocytic Phase - Asexual cycle in human liver (Patient is
asymptomatic in this stage):
Erythrocytic Phase - Asexual reproduction in RBCs (Patient is
symptomatic in this stage):
Presentation of Malaria
Symptoms can develop as early as 7 days after mosquito bite and as
late as several months or more after exposure.
The presentation of Malaria can be broken down into 2 broad
categories: Uncomplicated Malaria & Severe Malaria.
Paroxysmal fevers are typical of Malaria and considered a clinical
hallmark of the infection lasts 2-6 hours
Cycle repeats itself in 48 – 72 hours depending on species of
infection
Uncomplicated Malaria is characterized by:
(a) Paroxysmal (cyclical) fever
(b) Influenza-like symptoms including chills, headache,
myalgias, and malaise.
(c) Jaundice & mild anemia secondary to hemolysis
Severe malaria is characterized by:
(a) Small blood vessels infarction, capillary leakage and organ
dysfunction
(b) Altered consciousness
(c) Hepatic failure & renal failure
(d) Acute respiratory distress syndrome
(e) Severe anemia
Two reliable-supply treatment regimens available in the U.S. for malaria
(a) Atovaquone-proguanil (Malarone)
(b) Artemether-lumefantrine (Coartem)
Treatment of Uncomplicated Malaria
Chloroquine phosphate 1g PO
Malarone 4 tabs PO
QD for 3 days for chloroquine resistance
Treatment of Severe Malaria
(a) Artesunate 2.4mg/kg IV at 0, 12, 24, 48 hours
(b) Followed by Doxycycline 100mg BID x 7 days after
parenteral therapy
Treatment of P.ovale
ADD primaquine 52.6mg (30mg base = 2 tablets) PO QD x 14 days
For prevention of malaria resistance when should prophylactic medication be taken
Administration of prophylactic medication such as Chloroquine, &
Mefloquine, should begin 1-2 weeks prior to the expected embarkation
to an endemic area and continued for 4 weeks after leaving the
endemic area (except for Malarone, Primaquine, & Doxycycline; start
2 days prior to entry & continue till 7 days after departing;
Doxycycline to be continued till 1 month after departing).
Single-stranded RNA viruses of the genus Flavivirus
Dengue Fever
Common Name(s): ‘Breakbone fever’
Transmitted Via: Aedes aegypti mosquito; Mother to child; Blood
transfusion/organ donation (rarely).
Typically lasts 2–7 days and can be biphasic.
3 phases of Dengue Fever
(a) Febrile phase
Typically lasts 2–7 days and can be biphasic.
(b) Critical phase
Critical phase of Dengue begins at defervescence and typically lasts
24–48 hours.
(c) Convalescent phase
The patient’s hematocrit stabilizes or may fall because of the dilutional
effect of the reabsorbed fluid, and the white cell count usually starts to
rise, followed by a recovery of platelet count.
Critical Phase of Severe Dengue fever
Two hallmarks of Severe Dengue are infection-induced capillary
permeability (leaky capillaries) and disordered/diminished blood clotting.
Patient enters prolong shock all may seem well but once hypotension hits patien spirals and dies known as dengue shock syndrome
Dengue – Tourniquet Test
Obtain baseline BP & annotate the readings. Then, let the arm a
rest for 90-120 seconds.
Attach BP cuff, and inflate to a point midway between the
Systolic & Diastolic pressures obtained at baseline.
Keep inflated cuff on arm for 5 minutes, then deflate & wait
2 min.
Count petechiae below AC fossa.
A positive test is 10 or more petechiae per 1 square inch.
Dengue Fever – Treatment
Ensure patient stays well hydrated and avoid aspirin, aspirin
containing drugs, and NSAIDS because of their anticoagulant
properties.
Fever should be controlled with acetaminophen (Max 4g in 24 hrs.)
Severe: Typically requires ICU-level monitoring & blood products.
Maintenance of the patient’s body fluid volume is critical for
severe dengue care.
Scientific name: R. rickettsia
Rocky Mountain Spotted Fever
Incubation Period: Typically 2–14 days
RMSF – Early illness (days 1-4)
Fever, HA, GI symptoms, myalgias, edema
around eyes & back of hands, and rash.
Begins as small flat pink macules on wrists, forearms and
ankles that spreads to trunk
Can also involve palms of hands & soles of feet
RMSF – Late illness (day 5 or later)
(a) Neurological deficits
(b) Damage to internal organs (respiratory compromise, renal
failure)
(c) Vascular damage requiring amputation
A classic RMSF involves
a rash that appears 2-4 days after
the onset of fever as small, flat, pink, macules on the wrists, forearms, and ankles and spreads to include the trunk and
sometimes the palms of hands and soles of feet.
Petechiae are a sign of severe disease.
RMSF – Treatment
Doxycycline = Treatment of choice for all tickborne rickettsial
diseases. Doxycycline 100 mg PO BID for 5 – 7 days.
MedEvac patient to higher echelon of care.
When caught & treated early, RMSF may never progress in severity,
however, patient still requires MedEvac for monitoring and laboratory studies.
Scientific name: B. burgdorferi
Lyme Disease
Incubation Period: typically 3–30 days
Early Localized Stage lyme disease
Erythema migrans (EM)—Red ring-like or homogenous expanding
rash; Classic rash, not present in all cases.
EM appears about 1 week after the initial infection.
Lyme Disease Acute/Early Disseminated Stage
(a) Multiple secondary annular rashes
(b) Flu-like symptoms
(c) Lymphadenopathy
Cardiac Manifestations
Myocarditis, pericarditis
Neurologic Manifestations
Bell’s palsy, Meningitis,
Encephalitis
Lyme Disease
Late Disseminated Stage
Same symptoms as Acute Disseminated Stage, with:
Rheumatologic Manifestations
Lyme – Lab Diagnosis
(a) Acute/Early Disseminated: Two ELIZA test
(b) Late Disseminated: Either 2 ELIZA test, or 1 ELIZA test
followed by 1 Western blot (shows specific antigens of B.
burgdorferi are reacting with serum antibody).
Treatment of lyme disease
1) Doxycycline 100mg PO BID x 14 days unless late symptoms devolped that 28 days
Medication post-exposure prophylaxis Doxycycline 200mg PO 1 dose
Clinical suspicion of Lyme disease will necessitate Med Advice and treatment at the IDC level.
Leishmaniasis incubation period
Incubation Period: 2 weeks to several months and in cases up to 3
years; some >20 years.
Most common manifestation of leishmaniasis is cutaneous
(Begin as a pink colored papule that enlarges to a nodule or
plaque-like lesion.
(Lesion ulcerates with indurated border and may have thick
white-yellow fibrous material.
(Lesions are often painless
Cutaneous Leishmaniasis presentation
Treatment of Leishmaniasis
Ulcer should be debrided and kept clean to avoid secondary
infections from developing.
Any lesion with high suspicion for CL should be turfed to MO and/or
MTF Infectious Disease dept as soon as operationally allowable. CL is not lethal; however, it does require care far beyond the IDC.
FDA approved oral Miltefosine for treatment of CL, MCL, and VL caused by certain Leishmania species.
Treatment of choice for visceral leishmaniasis: Amphotericin B
deoxycholate.
Orally administered “azoles” (ketoconazole, itraconazole, &
fluconazole), & topical formulations of paromomycin for CL
Incubation MRSA
Highly variable; typically 4-10 days, but
asymptomatic (years)
Definition of MRSA
(a) Any strain of S. aureus that has developed multiple drug resistance(s) to beta-lactam antibiotics.
(b) CA-MRSA – Community-acquired MRSA seen in outpatient settings
(c) HA-MRSA – Hospital-acquired MRSA, typically nosocomial
MRSA Treatment
(1) Incision & drainage (I&D) is the mainstay of therapy for any fluctuant lesion secondary to MRSA.
(2) I&D is followed by proper packing of the wound, daily dressing changes, and oral antibiotics
(3) The following antibiotics may be used to treat a MRSA infection:
(a) TMP-SMX (160mg/800mg)
1) PO bid x 5-10 days
(b) Clindamycin 300 – 600mg
1) PO bid x 5-10 days
(c) Doxycycline 100mg
1) PO bid x 10 days
ABx prophylaxis requires empiric coverage of human oral/skin flora as well as reasonable MRSA coverage.
ABx without activity against Eikenella Corrodens should be avoided.
meaning you can not use
1) Cephalexin (keflex)
2) Penicillinase-resistant penicillins PRPs (dicloxacillin)
3) Macrolides (erythromycin & azithromycin)
Early antibiotic prophylaxis (wound not yet infected): Amoxicillin clavulanate 875/125mg PO BID x 5 days is the preferred Abx.
Labs for bites if concerned for osteomyelitis
1) CBC, ESR and CRP
make sure to image as well incase of Fx or foreign bodies
Risk factors of OM
Bacteremia, endocarditis, IV drug use, trauma, and open fractures.
2 pillars of OM Tx are
Surgical debridement of all diseased bone is often
required due to poor antibiotic penetration.
Empiric ABx therapy consists of IV
Vancomycin & IV Ceftriaxone.
Scientific name: Clostridium tetani
Tetanus
Incubation Period: 3 to 21 days, usually about 8 days. The further the inoculation the site is from CNS the longer the incubation period
Presentation of tetanus
(a) Typically the first sign is trismus or lockjaw, followed by nuchal rigidity, dysphagia, and rigidity of abdominal muscles.
(b) Muscle spasms may occur frequently (q10-15 min) and may last upwards of several minutes each episode.
(c) Other symptoms include hyperthermia, diaphoresis, hypertension, and episodic tachycardia.
Late symptoms of tetanus
(a) Periods of apnea due to contraction of thoracic muscles or pharyngeal muscle contraction.
(b) Fracture of long bones/ vertebrae during muscle spasms
(c) Nosocomial infections secondary to long-term
hospitalization, aspiration pneumonia
(d) Death typically occurs secondary to respiratory arrest.
Treatment of tetanus
(1) If you suspect actual tetanus in a patient:
(a) Immediate transfer to nearest MTF (Urgent MedEvac)
(b) Clean/debride wounds as best as possible
(c) Supportive therapy and airway protection
(2) Antibiotics:
(a) Metronidazole 500mg IV Q6-8H for 7-10 days
(b) Pen G 2-4Mil Units IV Q4-6hrs (alternate)
(c) Tetanus Immune Globulin (TIG, HTIG):
Classic triad meningitis
Fever, nuchal rigidity, altered mental status, & severe headache
incubation period
Incubation Period: Typically 4-6 weeks
typical presentation of Mono
Presents consistent with erythematous or exudative pharyngitis or
Tonsillitis.
Labs Mono
(a) CBC: leukocytosis with lymphocytosis is most often seen.
(b) May also see anemia, thrombocytopenia
(c) LFT: Potentially elevated aminotransferases
Treatment of Mono
(a) Bed rest, Acetaminophen or NSAIDS
(b) Saline gargles 3 – 4 times daily.
(c) Avoid the use of antivirals
(d) Steroids should only be used in cases where airway
obstruction is possible due to tonsillar enlargement
IM – DDx & Disposition
(1) Patients should be placed SIQ until acute symptoms subside.
(a) Fever resolves within 10 days, but the lymphadenopathy and splenomegaly may persist upwards of 3 - 4 weeks.
(b) Isolation is not necessary.
(2) Light duty with no physical contact sports for 3 – 4 weeks.
(a) Due to risk of splenomegaly and splenic rupture
(3) A MEDEVAC may be advised in severe cases where airway issues, or other complications arise.
Scientific name: Lyssavirus
Rabies
Rabies incubation period
Period: 1-3 months; length of incubation period dependent on site of inoculation.
Presentation of Rabies
The asymptomatic incubation period varies on how
distal/peripheral the infecting bite was from the CNS; Further from the CNS, the longer the symptom-free period.
Pain & paresthesia at the site of exposure are often the first symptoms of disease.
Disease progresses rapidly from a nonspecific, prodromal phase with fever and vague symptoms to an acute,
progressive encephalitis.
Clinical rabies typically manifests as 1 of 2 major forms:
Encephalitic “furious”
1) Fever, hydrophobia, pharyngeal spasms, hyperactivity subsiding to paralysis, coma
2) ANS instability: hypersalivation, lacrimation,
diaphoretic, “goose flesh”, dilated pupils.
Paralytic “dumb”
1) Ascending paralysis that is similar to Guillain-Barre
2) Lost of DTR & plantar reflex
