ID Flashcards
Cholera
Gm -ve rod
Diarrhoea - rice water stools
Enterotoxin => hypersecretion of water / chloride
Hypovolaemiic shock + metabolic acidosis + electrolyte disturbance
ABx shorten duration
Epi
Not common in Aus, endemic in some parts of the world
Transmission from contaminated water /(food)
Incubation few hrs to 5 days
Vaccine - not efficient - need booster every 6/12
Botulism
Rare and life threatening paralytic illness caused by neurotoxins produced by Clostridium botulinum inhibiting release of ACh at NMJ
Can lead to respiratory failure
Anaerobic, spore-forming bacillus found in soil
The D’s - diplopia, droopy eyes, dilated pupils, dry mouth, dysphonia, dysarthria
Symmetric descending paralysis - motor component only
TYPES of Botulism
- Food-borne botulism
- Ingestion of preformed heatlabile toxin rather than from the ingestion of spores or live bacteria
- One taste can expose a person to enough toxin to cause clinical illness
- Home-canning, mass produced foods, restaurants
- Infant botulism (the most common form of the illness now)
- Floppy baby syndrome - lethargy, poor feeding, weak cry, poor head control, loss of facial expression (bulbar palsy)
- Ingestion of spores with in vivo production of toxin
- Honey and to a lesser extent corn syrup
- Soil and vacuum ;ceaner dust ? cause
- Wound botulism
- IVDU using black tar heroin / dirty wounds / skin popping
- Inadvertent botulism / iatrogenic botulism
- Botox injection
- Biologic weapon of mass destruction
- Aerosolized form - Iraq
DDx
- GBS - ascending, sensory component, CSF protein raised
- MG - pupils spared, tensilon test, no autonomic Sx
- Tick paralysis - ascending, no bulbar Sx, TICK
- ACh- syndrome - pupils dilated + ACh delirium
- Infant
- Must have broad DDx - sepsis
- Other
- Brainstem CVA
- Infectious - Polio, Diptheria
- Med
Treatment
- Supportive ICU care
- Early Intubation - VC <30%
- Supportive care
- Ileus Mx
- Antitoxin
- Neutralises circulating toxin, effects of bound toxin irreversible
- Can cause anaphylaxis
- After skin testing for hypersensitivity, one 10-mL vial should be given IV.
- T1/2 - 5-8 days.
- Infant botulism - human botulism immune globulin (BabyBIG), which is pooled plasma from immunized adults with high titers of antibodies to toxins A and B.
- Antibiotics
- No recommended
- Used for prevention of secondary infection
Fever in the Returning Traveller
3 most important
Malaria - P. falciparum
Dengue Haemorrhagic Fever
Typhoid
Hx
Host Factors: past medical history, previous infections, diabetes, pregnancy, immunosuppression
Pre-travel Preparation: immunizations, malaria prophylaxis (type and compliance)
Specific Travel Itinerary: dates of travel, season of travel, destinations visited (regions, urban, rural), reason for travel, transportation
Exposure History: high-risk foods (local water, street food, uncooked meat), animal/insect exposure, bites, fresh water activities, blood and body fluid exposures (including sexual encounters, tattoos, IV drug use), sick contacts, health of fellow travelers
Examination
- Vital signs (paradoxical bradycardia is sometimes seen in Typhoid fever)
- Neurologic Exam: mental status, meningismus
- Dermatologic Exam: skin lesions (rose spots of Typhoid fever, “islands of white in a sea of red” Dengue rash, eschar associated with tick bites of Rickettsia), petechiae, jaundice
- GI: hepatospenomegaly
- Lymphadenopathy
Ix
- FBC & diff (look for anemia, lymphopenia, thrombocytopenia)
- UECs
- Liver enzymes (AST/ALT - viral hepatitis/malaria), Br and lipase
- Hypoglycaemia
- Blood cultures x 2
- Malaria Screen: thick and thin smears are required every 12 hours until there are three negative smears. Three negative smears are required to rule out Malaria as parasitemia is cyclical.
- Dengue serology
Tropical Infections - Incubation periods
< 7-10 days
- Dengue fever, 5-8 days
- Meningococcal disease, variable
- Japanese B encephalitis, 4-14 days
- Yellow fever, 3-6 days
- Zika virus
- Rickettsial diseases
- viral haemorrhagic fevers, Ebola, 2-7 days
7-30 days
- Hepatitis A, 15-45 days
- leptospirosis
- malaria, 2-8 weeks for Falciparum
- amoebic dysentery, 7-21 days
- enteric (typhoid) fever, 7-14 days
- giardiasis, 2 weeks
- Rickettsial disease
- Lassa fever, 7-18 days
1-6 months
- acute schistosomiasis, 4-8 weeks
- Strongyloides, weeks to years
- filariasis, weeks to years
- viral hepatitis, weeks to months
Malaria
Species:
P. falciparum 75%, most severe (Africa, SE Asia, SA America)
P. knowlesi - can be severe (SE Asia)
P. vivax, malariae (20%), ovale - less severe
Sickle cell trait, Thalassaemia, G6PD = protective
Transmission:
Mosquito, Blood Transfusion, Maternal- Foetal transmission, Dirty needles
Incubation: 8d-4 weeks, can be 12 months!!!!
Presentation:
The ‘classic triad’ is fever, splenomegaly, and thrombocytopenia
Symptoms/ Signs
* Fever > 90%
* Cyclical - every 2-3 days but not always
* Continuous fever
* Headaches
* Jt aches
* N/V/D
* Jaundice
* Splenomegaly
* Altered conscious state / seizures / coma
Ix
Blood film - parasite load >2% to confirm and> 5% = severe
Thick = parasite presence
Thin = species typing
Repeat smears every 12 hours until 3 x negative smears
Malaria antigen test
FBC - anaemia, thrombocytopaenia
UECs - deranged electrolytes
LFTs - high Br
Coags - DIC (rare)
Haemolysis (Coomb’s +ve)
Hypoglycaemia
LP to exlude bacterial meningitis
CSF - may be normal or elevated protein /opening pressures, low glucose
Rx
* Anti-malarial therapy
* IV therapy for severe
* organ dysfunction (ARDS, ARF etc), anaemia, cerebral malaria, hypotension
* Artesunate 2.4g IV (superior)
* Quinine 20mg/kg IV (beware longQT) + doxycycline (clindamycin for pregnancy or children < 8yrs)
Protective:
Chemoprophylaxis
Haem: Sickle cell, Thalassaemia, G6PD
Typhoid
Water/food borne
Incubation 7-14 days
Fever stepwise rising over the course of each day
Relative bradycardia
Rose spots
- 2-4mm blanching macules
- trunk / extremities
- resolve 2-5 days
The presentation can be divided into 3 weeks:
Week 1: diffuse abdominal pain and tenderness, constipation, dry cough, frontal headache, delirium, and an increasingly stuporous malaise
Week 2: Rose spots, progression of GI symptoms with abdominal distension, relative bradycardia
Week 3: weight loss, conjunctival injection, tachypnea, thready plulse, crackles over the lung bases, ‘pea soup’ diarrhea, apathy, confusion, and even psychosis, peritonitis
Ix
Positive BC - Gm -ve bacilli
Rx
* Ciprofloxacin
* Ceftriaxone
* Azithromycin
Prevention - vaccine
Dengue
Arbovirus, 4 known serotypes
Transmission: Mosquitos
Incubation: 3-14d
Reservoir: humans
Susceptibility: infection -> lifetime immunity form that serotype but no protection against other serotypes
Saddleback fever - a bimodal fever that persists for 3 days, resolves, and peaks again in 1-2 days
The WHO definition of Dengue includes:
- Fever
- Two or more of:
- Rash – petechia or “islands of white in a sea of red” (see image)
- Arthralgias
- Nausea/Vomiting
- Positive tourniquet test (inflate BP cuff and leave it inflated for 5 minutes, on deflation, look distally for petechiae).
- Leukopenia
Classic dengue - benign course
Dengue Haemorrhagic Fever
- small no - mostly children < 10yrs
- pharyngitis, cough, N+V,
- AP
- Hepatomegaly
- Bleeding and DIC
Dengue Shock Syndrome
- 20-30% of DHF cases
- Massive plasma leak = pl effusions, acsites, hypovolaemic shock, DIC + massive haemorrhage
- Rx supportive with PRBC and judicious fluids
Infective Rashes
Rose spots - typhoid
Islands of white in a sea of red - dengue
Eschar - tick bite
TB - Signs and Symptoms
Primary Disease
- Ghon focus = 1-2cm subpleural lesion w/ central caseation and fibrotic walling off lof lesion
- Ghon complex = Ghon focus + hilar lymphadenopathy
- Usually in chldren of those not previously exposed to TB
Secondary disease
- Re-activation of latent TB or re-infection
- Usual site apex of lung or apical segments of lower lobes
Complications
- Pulmonary
- Cavitation = high bacterial load
- Broncho-pneumonia
- Miliary TB
- Erosion of blood vessels => haemoptysis
- Laryngeal
- Renal = CRF
- GIT = obstruction/adhesions/perforation
- CNS = Tuberculous meningitis
- Lymph = scrofula
- Skeletal = spinal (Pott’s)
- Adrenal = chronic adrenal insufficiency
- GU = epididymitis or chronic PID
TB RF and Management
RF - highest to lowest risk
- Immigrants from high prevalence coutries
- HIV/AIDS
- Sub-standardliving, institutions i.e prison
- Immunosuppression
- Malnourished
- (DM/IVDU/elderly/alcoholics)
- Elderly NH residents
Rx
* Isoniazid
* Rifampicin
* Pyrazinamide
* Ethambutol
Above for 2/12, then isoniazid + rifampicin for 4/12
TB Diagnosis
Infectivity (highest to lwest)
1. +ve sputum smear AND +ve sputum culture
2. -ve smear AND +ve sputum cultre
3. -ve smear and culture
4. Extra-pulmonary disease
Diagnosis
1. Hx
2. Delayed hypersensitivity immunological testing
a. Mantoux - Tuberculin Skin Test (See attached)
b. Quantiferonin - Blood Test
Pro - Result w/in 24 hours, single visit, less reader bias,
Cons - Blood test, not differentiate active and latent infection
3. CXR/CT
- Consolidation upper and mid-zone prevelance
- Hilar lymphadenopathy
- Cavitating lesions
- Ghon focus - subpleural calcifcation remains after inital infection
- Fibrosis calcification
- Tuberculoma - well defined mass
- Miliar Pattern - small nodules throughout the lungs
- PCR
Notifiable Diseases
- Diphtheria
- Mumps
- Poliomyelitis
- Haemophilus influenzae Type b
- Meningococcal disease
- Rubella
- Measles
- Pertussis
- Tetanus
HIV / AIDs classifications
as per CDC
AIDS = A3, B3, C1, C2, C3
HIV Infection WHO case definitions
HIV + Fever DDx
- HIV infection itself
- Pneumocystis carinii pneumonia
- Mycobacterial disease
- Cryptococcal disease
- CMV infection
- disseminated Herpes
- drug fever
- lymphoma
- wide range of other infections
- Pneumococcus, Staph
- SBE
- other opportunistic agents
AIDS defining Illnesses
- Pneumocystis carinii pneumonia 60%
- cerebral Toxoplasmosis 15%
- encephalopathy 10%
- CMV retinopathy 5%
- Kaposi’s sarcoma 2%
- tuberculosis 2%
- cryptococcal meningitis 2%
- others 1%
Bloods HIV Testing
- FBC
- Anaemia / thrombocytopaenia
- CD4 count
- Antibodies
- Serology
- ELISA
- Western Blot
- Viral Antigen
- p24 antigen detects viral load
- Gp 41/120/160
- Monitor therapy
- PCR
Syhpilis
Proctitis
Sexually transmitted > radiation > autoimmune
Mumps
+ve Blood Culture Interpretation
LP interpretation
SAH
Br + Xanthochromia from 4th tube
RBC > 1000 suggest not from traumatic tap
Severe Malaria
Dengue Case Definitions - WHO
CDC Criteria for TSS
TSS - Compare Staph vs Strep
Roseola Infantum
LGV
Genital Ulcers
Rosh Review TB Summary
Caused by Mycobacterium tuberculosis
Risk factors: HIV, immigration from an endemic area, immunosuppression, malnutrition
Primary TB
Usually asymptomatic and progresses to latent TB with no intervention
CXR: often normal, hilar adenopathy, Ghon focus
Latent TB
Asymptomatic
Screening: tuberculin skin test (TST) or interferon-gamma release assay (IGRA)
Tx: rifampin for 4 months, INH-rifampin daily for 3 months, or INH-rifapentine weekly for 3 months. Alternative is INH for 9 months or 6 months.
Reactivation TB
Sx: fever, night sweats, weight loss, productive cough, hemoptysis
CXR: upper lobe infiltrates, apical cavitary lesions
Dx: sputum smears for acid-fast bacilli (AFB) x3, sputum or tissue culture for AFB (gold standard)
Tx: rifampin, INH, pyrazinamide, ethambutol (RIPE) for 6 months
Monitor LFTs, add vitamin B6 (prevent peripheral neuropathy due to INH)
Comment: Positive TST determined by mm of induration and risk factors
15 mm: people with no known risk factors
10 mm: immigration from high-prevalence countries < 5 years ago, injection drug use, residents/employees of high risk settings (homeless shelter, correctional facilities, hospitals, nursing homes), children < 4 years old or exposed to adults in high risk categories
5 mm: HIV infection, recent TB contact, CXR consistent with prior TB, organ transplant, TNF-α inhibitors or chronic steroids
