Diarrhea Flashcards
1
Q
Harms of early childhood diarrhea
A
- growth stunting
- brain development stunting (most before age 2)
- tied to lower IQ if high burden
*highest burden in the developing world
2
Q
Definition of diarrhea
Acute watery vs bloody vs persistent
A
- passage of 3 or more loose stools in 24 hours
OR >200mL of stool/day
acute watery - hours to days
bloody - inflammatory
persistent - 2+ weeks
chronic - 4+ weeks
3
Q
Why are children at higher risk of diarrhea?
A
- higher metabolic rate
- higher body surface area to weight ratio
- higher respiratory losses
4
Q
Signs and symptoms of:
- minimal/ no dehydration
- mild/moderate dehydration
- severe dehydration
A
- minimal - normal to decreased urine output
- under 3% weight loss
- moderate - restless, fatigued, thirsty, increased HR, decreased quality of pulses, slightly sunken eyes, less tears, dry mouth, cool extremities, delayed skin recoil and cap refill, decreased urine output
- 3-9% weight loss
- severe - lethargic, unconscious, tachycardia and Brady if severe, no tears, cyanotic/ mottled, impalpable pulses
- over 9% weight loss
5
Q
Treatment for:
- mild dehydration
- moderate dehydration
- severe dehydration
A
Mild - often no rehydration therapy needed
Moderate - ORS 50-100mL/kg over 3-4 hours
Severe - IV resuscitation with 20mL/kg saline or Ringer’s lactate for 1h, then 100mL/kg ORS over 5 hours in 1/2 normal saline IV
*if under 10kg weight loss, 60-120mL ORS per stool/vomit
* if over 10kg weight loss, 120-140mL ORS per stool/vomit
*for all 3, continue breast feeding and normal diet
6
Q
ORS
- how do they work?
- pros?
A
- oral rehydration salts
- based on Na and glucose transport coupling via SGLT1 from lumen into epithelial cells (glucose accelerates absorption of solute and water
- ultimately results in more water absorption into blood
- cheap, no need for IV, can be given at home, no risk of salt imbalances
7
Q
Other options for treating dehydration besides ORS
A
- early refeeding
- anti-emetics (ondansentron a 5-HT3 antagonist, metoclopramide, domperidone which are dopamine antagonists)
- ABX if dysentery
- zinc in the developing world
8
Q
Lab tests for dehydration
A
- likely necessary in most mild/moderate cases
- lytes/BUN/Cr if severe or HUS concern
- stool microbiology if severe/systemic/bloody/chronic/ young/immunocompromised/travel/outbreak
9
Q
Common organisms causing diarrhea
A
- rotavirus
- shigella
- ST-ETEC
- cryptosporidium
- typical E.coli
10
Q
Early vs late causes of death in diarrhea. Which is more common?
A
Early - dehydration, lyte imbalances, sepsis
Late - structural changes (blunted villi, deep crypts, inflammation can lead to malnutrition), gut dysbiosis, immune dysfunction, recurrent diarrhea
- late deaths are 2/3rds of all deaths
- odds of dying in follow-up much higher if moderate/severe diarrhea
11
Q
Water sanitation vaccines
A
- i.e. rotavirus vaccine
- have higher efficacy in higher GDP countries
12
Q
Thing that lower vaccine viral titre or impair the immune response
A
- breast feeding, stomach acid, maternal Ab, OPV lower titer
- malnutrition (vit A, zinc), interfering microbes, other infxns (HIV, malaria, TB) impair immunity
13
Q
ABX treatment of Shigella/ trachoma in LMICs
A
- single dose azithromycin
14
Q
Where are the majority of gut organisms? What species predominate?
A
large bowel (mostly anaerobes, E.coli)
15
Q
Role of gut microbiome
A
- could be linked to immunity, allergy, asthma, obesity, cancer, IBS/D, artherosclerosis, and autism
- SCFAs affect BBB –> stress, pain, cognition
- epithelial homeostasis, pathogen protection, nutrient absorption/ fermentation (make B12, folate, vit K, thiamine, etc.), make SCFAs, metabolize bile acids
- 95% of the human microbiome is in the gut!
16
Q
Organisms found in:
- water
- oysters/cruisehsips
- children
- food/people/animals
- sheep/cows/produce
- food/people
- food/people/reptiles/ raw eggs
- daycare
A
water - giardia, cryptosporidium, cholera, entamoeba histolytica
oysters/ cruisehips - norovirus
children - rotavirus (most likely to cause hospitalization)
people/food/animals - E. coli ETEC
sheep/cows/produce - E.coli STEC
food/people - shigella
food/people/reptiles/raw eggs - salmonella
daycare - EHEC, shigella, noro/rotavirus
17
Q
Secretory/ Disordered Electrolyte Transport Diarrhea
- common organisms
- sx
A
- increased secretion of anions (Cl, HCO3) and/or inhibition of Na absorption
- watery, continuous despite increased intake/ fasting
- large stools with a normal proctoscopy
- mid abdomen pain
- often SI (cholera, E.coli, rota/norovirus, giardia)
- cholera is the prototype: interferes with Na/K/Cl transport in enterocytes, more Cl secreted into the lumen (treat with doxy if outbreak)
18
Q
Inflammatory Diarrhea
- common organisms
- sx
A
- exudative and protein losses, damage can be direct or immune
- osmotic secondary to loss of absorptive surface, secretory secondary to inflammatory mediators
- fever, bloody stool, WBCs in stool, tenesmus
- lower abdomen and rectal pain
- small stools with mucosal/friable ulcers
- often LI (E.coli, salmonella, shigella, C.diff, E.histolytica, campylobacter)
19
Q
C. Diff
- type of organism
- causes
- consequences
- toxins
- Dx
- Tx
A
- gram (+) bacillus
- ABX associated, ESPECIALLY broad spectrum such as ceftriaxone, ciprofloxacin, clindamycin
- also common with PPIs (less acid to kill spores), institutionalized elderly
- can lead to pseudomembranous colitis, bloody diarrhea, IBS, toxic megacolon, intestinal perforation, sepsis, death
- A (entertoxin) and B (cytotoxin) - fluid accumulation, inflammation, increased permeability
Dx - test stool for A/B toxins using ELISA/PCR (B)/culture
Tx - stop ABX, stool transplant, metronidazole or vancomycin or fidaxomicin, surgery if toxic megacolon
20
Q
E. coli
- type of organism
- reservoir
- virulence factors
- different types
A
- gram (-) bacilli, can be part of normal gut flora
- reservoir in guts of humans and animals
- most common cause of UTIs
- fimbriae, adhesins, exotoxins (secreted shiga toxin), endotoxin (LPS that prevent phagocytosis, part of cell)
- ETEC - toxigenic
- EPEC - pathogenic
- EIEC - invasive
- EAEC - aggregative
- EHEC - hemorrhagic (aka STEC - shiga-toxin producing 0157:H7)
21
Q
ETEC
- sx
- causes
- toxins
- Tx
A
- mild watery diarrhea and nausea, NO vomiting, often self-resolving
- traveler’s diarrhea
- ingestion of focally contaminated food and water
- need a LOT to cause disease
- heat labile (LT) and heat stable (ST) toxin
- TX: oral rehydration, traveler’s diarrhea vaccine (Dukoral)
22
Q
STEC (EHEC)
- sx
- causes
- toxins
- what can it lead to?
- tx
A
- 0157:H7
- gut of cows and other ruminants, ingestion of cow fecal matter (need a LITTLE to cause disease)
- usually bloody diarrhea
-shigatoxin AB - halts protein synthesis in entero/epithelial cells - TX - only supportive, NO ABX
- can lead to HUS (hamburger disease) - low Hgb (schistocytes and helmet cells), not producing urine
- prodrome of D/V, abdominal pain, 5-10 days later will get oliguria, anemia, lethargy, HTN, renal failure
23
Q
Salmonella (non-typhoidal vs. typhoidal)
A
Non-typhoidal
- usually non-invasive and self-resolving (4-5 days)
- zoonotic, foodborne (lizards, eggs, fecal contamination)
- acute diarrhea, fever, abdominal pain
- under 5% get invasive (infants, 65+, comorbid)
- no ABX treatment unless invasive or severe
Typhoidal
- only humans are reservoir, fecal-oral transmission
- gastroenteritis, typhoid fever (invasion of peyer’s patches leading to rash, fever, bacteremia and ileum perforation)
- asymptomatic carriage in the gallbladder
- capsular Ag prevents phagocytosis
- Tx: ABX, prevention with hygiene and vaccine
- Dx: bacteriology or molecular PCR
24
Q
H. Pylori
- transmission
- virulence factors
- what can it lead to
- sx
- tx
A
- fecal-oral, oral-oral transmission
- infects lower stomach antrum, urease to neutralize acid, spiral flagella, mucolytic enzymes, adhesions to epithelial receptors
- most common cause of gastritis (duodenal and gastric ulcers, increases risk of gastric cancer), most common chronic bacterial infix
- seroprevalence dependant on age and SES
- nausea, vomiting, epigastric pain, anorexia, acid reflux
Tx - quadruple therapy for 14 days (2nd option is if penicillin allergy)
- PPI BID
- clarithromycin or bismuth
- amoxicillin or metronidazole
- metronidazole or tetracycline
- test for eradication 4 weeks off ABX and 2 weeks off PPI
25
Test for H. pylori - who should be tested?
- urease breath test (urea --> NH4 and labeled CO2)
- stool Ag test
- endoscopy if alarm features/ drug resistance (bleed, anemia, weight loss, dysphagia, hx of cancer, early satiety)
- serology very sensitive but (+) up to 18m
- test if dyspepsia, hx of ulcers or upper GI bleeds or gastric cancer, immigrants, indigenous
26
Hepatitis A
- picornavirus, fecal-oral
- replicates in hepatocytes
- fatigue, N/V/D, abdominal pain --> jaundice, pruritic, dark urine, pale stools, usually self-limiting and liver failure is uncommon
- cryoglobinemia, glomerulonephritis, arthritis, leukovasculitis
- Tx: supportive, vaccine (2 doses 6m apart, recommended for everyone 6m and older) recovery in 2-3 months
- no chronic illness and immunity is lifelong
27
Food poisoning definition
staph aureus vs bacillus cereus food poisoning
- acute onset of N/V and pain within 1-6 hours of ingestion, resolves within 24 hours without treatment
staph aureus - multiplies at room temp and produces enterotoxin
bacillus cereus - common in rice, spores survive cooking and germinate, produce enterotoxin at room temp
28
Clostridium botulinum (botulism)
- type of organism
- causes
- toxin
- consequences (in infants and adults)
- dx
- tx
- gram (+) spore forming rod anaerobe
- common in soil, vegetation
- germinates in low oxygen environment and produces neurotoxin that cleaves SNARE proteins (prevents Ash release)
- can germinate in infant guts and cause floppy Abby syndrome (hypotonia)
- in adults - double vision, dropping eyelids, dry mouth, dizziness, dysarthria, dysphagia, diaphragm paralysis and death
- Dx: clinical, toxin detection in stool and serum
- Tx: anti-toxin IgG and respiratory support
29
Abdominal Abscess
- what is it and what can it cause
- most common pathogens
- tx
- disruption of the bowel wall allowing normal flora to cause disease int he peritoneum
- mechanical obstruction, inflammation, surgery, etc.
- WBC are recruited, can lead to necrotic death
- most common pathogens are E.coli and bacteroides, but can also be candida/enterococcus if ABX/ hospital
- Tx: if septic pip-tazo OR ceftraixone + metronidazole (always have anaerobe coverage)
- surgical drainage
30
Typical Bowel Flora
- enterobacter (E.coli, proteus, klebsellia, enterbacter)
- anaerobes (bacteroides, clostridium, fusobacterium)
- strep/enterococcus, candida, staph aureus
31
Tx for Amoebic Liver abscess caused by entamoeba hystolitica
- metronidazole 5-10 days, paramomycin or iodoquinol
- common in MSM and immigrants
32
Esophagitis
(immunocompromised)
- Candida albicans yeast colonizes
- infection with loss of mucosal barrier, immune deficiency, ABX use
- oral thrush is the most common opportunistic HIV infection - dysphagia, odynophagia, N/V, anorexia
Tx - fluconazole 14-21 days
33
HSV
(immunocompromised)
- reactivation of herpes virus
- most commonly oral/CNS/esophagitis/hepatitis/genital ulcers
Tx - acyclovir, valacyclovir, prophylaxis if outbreak
34
CMV
(immunocompromised)
- reactivation of herpes virus
- most commonly esophagitis/ retinitis/ colitis/ hepatitis/ pneumonia
Tx - ganciclovir, valganciclovir, reduce immune suppression
35
Mycobacterium Avium Complex (MAC)
(immunocompromised)
- non-TB mycobacterium in soil and water
- can colonize respiratory or GI tract
- Dx: fever/ fatigue/ weight loss/ diarrhea/ cough/ lymphadenopathy, imaging, culture, histology of colon/bm/lymph nodes
Tx - rifabutin, ethambutol. clarithromycin, decrease immune suppression
36
Protozoa
(immunocompromised)
- can cause chronic diarrhea
- treat with TMP-SMX
37
Strongyloides Stercoralis
- roundworm
- enter via feet into lungs then SI
- Gi hemorrhage, gram (-) bacteremia, meningitis, pneumonitis
38
Examples of inhibitors of:
- B-lactams
- Folate synthesis
- Nucleic Acid synthesis
- DNA gyrase
- 50S subunit
- 30S subunit
- Cell membrane
- Cell wall synthesis
- B-lactams - penicillins, cephalosporins, carbapenems
- Folate synthesis - sulphonamides, trimethoprim
- Nucleic Acid synthesis - metronidazole
- DNA gyrase - quinolones
- 50S subunit - macrolides, clindamycin, linezolid
- 30S subunit - tetracyclines
- Cell membrane - daptomycin
- Cell wall synthesis - vancomycin
39
ABX that are 90%+ bioavailable
- doxycycline
- metronidazole
- TMP-SMX
- rifampin
- linezolid
- fluconazole
- fluroquinolones
40
Gram (+) Bacilli vs Cocci
bacilli - clostridium, listeria, corynebacterium, bacillus
cocci - streptococcus, enterococcus, staphylococcus
41
Tx for:
- Listeria
- Enterococcus
- Strep pneumo
- Strep A/B/C
- Viridans Group Strep
- Staph Aureus (MSSA and MRSA)
- Listeria - Ampicillin
- Enterococcus - Ampicillin/ Amoxicillin
- Strep pneumo - Amoxicillin/ Penicillin or Ceftriaxone/ Cefuroxime
- Strep A/B/C - Penicillin
- Viridans Group Strep - Penicillin
- Staph Aureus (MSSA and MRSA) - Cloxacillin or Cephalexin/Cefazolin for MSSA, Vancomycin for MRSA
42
Vancomycin
- MOA
- use
- S/E
- inhibits peptidoglycan (and thus cell wall) synthesis
- only acts against gram (+)
- nephrotoxicity, rash, cytopenias, red man syndrome
- SAFE IN PREGNANCY AND CHILDREN
43
Daptomycin
- MOA
- use
- S/E
- binds bacterial membrane and causes depolarization, K efflux, and cell death
- only IV and only works against gram (+)
- commonly used for MRSA and VRE infections if vancomycin cannot be used
- increased CK levels, muscle weakness, myalgia
44
Linezolid
- binds and prevents translocation (50S), thus preventing protein synthesis
- only works against gram (+)
- both IV and oral, great bioavailability
- commonly used for MRSA and VRE infections
- serotonin syndrome if on SSRIs, neuropathy, bone marrow suppression
45
Gram (-) cocci vs. coccoid rods vs. rods
Cocci - n.meningitidis, n.gonorrheae
Coccoid rods - H. flu, B. pertussis
Rods - pseudomonas, shigella, salmonella, enterbacteraciaea
46
What is the major resistance mechanism in gram (-)? Which organisms have these? What drugs counteract this?
- B-lactamases
SPACE organisms aka ESBL (ampC gene):
- Serratia
- Proteus/ Pseudomonas
- Acinetobacter
- Citrobacter
- Enterobacter
- pip-TAZO and amox-CLAV
- carbapenems
47
Concerns for gram (-) organisms
- lower GI and GU infections
- nosocomial infections (HAP)
- chronic wound infections with previous BAX use
48
Which ABX do you use for:
- ESBL
- pseudomonas
- N. gonorrhea
- H. flu
- enterbacteraciae
ESBL - carbapenems
pseudomonas - carbapenems, pip-tazo
N. gonorrhoea - ceftriaxone/ cefixime and azithro
H. flu - amoxicillin-clav
Enterobacteraciaea - amor-clav, pip-tazo, carbapenems, ceftriaxone
49
TMP-SMX
- uses
- s/e
- MRSA, listeria, pneumocystis jirovecii
- hyperkalemia, rash (SJS), nephrotoxicity, neutropenia, hemolytic anemia, kernicterus (NO in last 2m of pregnancy and 1st year of life)
50
Examples of anaerobic bacteria
- C. diff and actinomycetes (+)
- Bacteroides and fusobacterium (-)
51
Metronidazole
- MOA
- uses
- s/e
- disrupts DNA synthesis in anaerobes and protozoa
- 1st line for non-severe C. diff, giardia, bacteroides, H. pylori, bacterial vaginosis
- N/D, metallic taste, cannot take with alcohol
- OK IN PREGNANCY
52
Clindamycin
- MOA
- uses
- binds and blocks peptide exit thus inhibiting protein synthesis (50S)
- oral anaerobes, MRSA, severe group A strep, necrotizing fasciitis
53
Rule of thumb ABX for:
- above the diaphragm
- below the diaphragm
- everywhere
- Above - clindamycin and metronidazole
- Below - metronidazole (i.e. acute GI infection, likely gram (-) and anaerobes)
- Everywhere - pip-tazo, amox-clav, carbapenems
54
Bristol Stool Chart
1 - hard lumps
7 - entirely liquid
- 6 or 7 is considered diarrhea
55
How is water absorbed in the intestines? Where is most of it absorbed?
- salt-driven (glucose dependent Na/K transport)
- occurs near tip of villi
- most water is absorbed in the jejunum (6L), in contrast max colonic absorption is 4L which has an active Na/K channel
56
Osmotic/ Malabsorptive Diarrhea
- poorly/ non-absorbed solutes (Mg, PO4, lactose, lactulose, sucrose, sorbitol, mannitol)
- intestines cannot maintain the osmotic gradient and thus water tension in the lumen is needed to maintain osmolality
- can be caused by laxatives (PEG), congenital sugar malabsorption, celiacs
- disappears with fasting/ stopped consumption of the offending agent
57
Altered Intestinal Transit Diarrhea
- more fluid = propulsion = decreased absorption = diarrhea
- slow transit can lead to SI bacterial overgrowth, leading to fat malabsorption and bile acid secretory diarrhea (DM, autonomic neuropathy, post OP)
58
Causes of chronic diarrhea
- protozoa (giardia, cryptosporidium)
- C.diff
- TB (in general, higher risk if immunocompromised)
- fatty - malabsorption and maldigestion (celiac's, chronic pancreatitis)
- inflamm - diverticulitis, IBD, neoplasia, TB, C.diff, CMV, HSV, parasites
- watery - IBS, Addison's, neuropathy, hyperTH, hypoPTH, LOTS of stuff
59
Dietary drug causes of diarrhea
- excess coffee, alcohol, antacids, ABX, NSAIDs, SSRIs
60
Bile Acid Malabsorption Diarrhea
- common in IBD
- primary - impaired FGF19 feedback
- secondary - Crohn's, DM, resections, chemo, cholecystectomy
61
Chronic Pancreatitis
- malabsorption when exocrine secretion capacity is under 90%
- lipase and co-lipase will fall first, leading to fatty osmotic diarrhea
62
Use of fecal calprotectin
- correlates with inflammatory diarrhea if 200+
- NOT specific for IBD
63
Tests for:
- SIBO
- pancreatic insufficiency
- crohn's
- watery, new sx 40+, hemochezia, alarm sx, anemia, increased CRP or calprotectin
- SIBO - glucose hydrogen breath test
- pancreatic insufficiency - fecal elastase, pancreatic CT, secretin/CCK stim tests
- Crohn's - MR/CT enterography
- watery, new sx 40+, hemochezia, alarm sx, anemia, increased CRP or calprotectin - colonoscopy
64
Antidiarrheals
- loperamide (ammonium) - m-opioid agonist
- opiates, codeine, cholestyramine, bismuth subsalicylate, anticholinergics kaolin, psyllium, cellulose
- NEVER use if fever/ abdominal distension
65
Celiac's
- increased immune response to Gliadins
- HLA-DQ2 haplotype in 90%, HLA-DQ8 in rest
- EMA IgA and ttG IgA
- SI biopsy is required for diagnosis
- can be asx, epilepsy, arthritis, myopathy, dermatitis herpetiformis, malnutrition, osteoporosis, malignancy, T1DM, dementia
- osmotic fatty diarrhea due to malabsorption
- less villi, crypt hyperplasia, bile irritation (secretory and inflammatory)
- Tx - gluten exclusion, steroids and immunosuppressants
66
IBD (Crohn's vs UC)
-tx?
Crohn's - any part of GI tract, inflammation penetrates leading to ulcers (transmural), skip lesions, stenoses/ fistulas, granulomata
- smoking hurts
UC - only in LI, always affects rectum, continuous, mucosal, never SI or anus
- smoking helps
Tx - prednisone/budesonide --> AZA/MTX --> biologics (JAKis i.e. tofactinib for UC) --> surgery
- anti-TNFs (infliximab)
67
Where are bacteria more abundant in the gut?
- proximally and where higher pH
68
Dominating gut biome species in infants vs adults
- bifidobacteriaciae
- firmicutes and bacteroidetes
69
Why are plant protein and fiber good for us?
- decrease inflammation by increasing SCFA production
- maintain healthy pH, associated with bacterial richness
70
Prebiotics
- inulin, FOS/GOS, lactulose (mainly plant foods)
- stimulate SCFAs, increase satiety/ glycemic control/ Ca absorption/ mucosal barrier, decrease inflammation/ toxins
*not much evidence supporting probiotics
71
Drugs that affect the microbiome
- metformin, NSAIDs, atypical antipsychotics
- PPIs have biggest effect after ABX (increased risk of C.diff and campylobacter)
72
Consequences of dysbiosis
- alteration of bile acids --> inflammation --> decreased motility --> GI cancer
73
Vomiting Red Flags in Children
- neonates (especially in bilious)
- projectile
- hypovolemia/ shock
- severe abdominal pain, peritonitis
- lethargy
- fever (+/- stiff neck/ headache) epsecially if travel history
*UTI very common cause of fever and vomiting in children, always test
74
Intussusception
- bowel telescopes in on itself (commonly ileocecal)
- young (3m-3y), acute episodes of cramps pain and vomiting, bilious emesis, stiffening and pulling of legs to abdomen, lethargy or low LOC
- may feel well and fall asleep in-between episodes
- "red currant jelly" bloody stool
- life threatening!
- Dx - U/S, barium/air enema
* a 1 day old with bilious vomiting is often a surgical cause
75
Hypertrophic pyloric stenosis
- 3w-3m
- non-bilious vomiting
- Dx w U/S
76
Corynebacterium Diptheriae
- tx
- common upper respiratory pathogen leading to pharyngitis and pseudomembrane over tonsils - can lead to obstruction and death (bull neck)
- person-person spread
Tx - penicillin or azithromycin, supportive
77
Case Reproduction Number (R)
- average number of secondary cases attributable to a single case
- anything more than 1 allows for an epidemic
- R = contact rate x transmission risk per contact
- R=1 means disease is endemic
- R=3 is intitial phase of epidemic (exponential growth)
78
Odds Risk (OR)
- odds disease if exposed/ odds disease if unexposed
Disease?
+ -
Exposure + A. B
- C. D
= (A/B)/ (C/D) or (AD/BC)
79
When to use empiric treatment for diarrhea
- good evidence for traveler's diarrhea --> loperamide
- ciprofloxacin or azithro if SE Asia
- no if bloody unless younger than 3 months, severely ill with a fever, or recent exposure to shigella
- no in watery diarrhea unless infant or immunocompromised
- only use for C.diff if leukocytosis/ abdo pain/ AKI
80
What should you never treat?
EHEC 0157:H7, other STEC, and salmonella (unless chronic carrier with high risk of transmission
81
Test Cure for ABX treatment
- don't bother, post-tx colonization is very common
- goal is to eliminate toxin, not the organism
82
Major determinant of development and education and subsequent obesity and non-communicable diseases in adulthood
Major roots of inequity
Protective Factors
- undernutrition in 1st 1000 days of life
- poverty, status of women, less education, war
- breast feeding, maternal education, support programs
83
Micronutrient Supplementation
- iron (anemia, developmental delay, energy, learning)
- iodine (developmental delay)
- zinc (pneumonia, diarrhea)
- vit A (eyesight, measles mortality)
84
Malaria
- carried by? transmission?
- most common type?
- MOA?
- immunity?
- cause of returning traveller fever until proven otherwise
- carried by female anopheles mosquito
- bites occur at night, transmission is temperature dependent
- plasmodium falciparum is most common and most serious
- parasites multiply in liver cells and RBCs (lyse)
- can have partial immunity in areas of constant transmission
- immigrant immunity wanes in 6 months
85
Uncomplicated malaria vs. severe malaria (p. falciparum)
- fever, rigours, headache, myalgia, anorexia
- +/- jaundice, splenomegaly, pallor if chronic
- confusion (even intermittent), seizures, coma, renal failure, pulmonary edema, hypoglycaemia, lactic acidosis, coagulation issues, jaundice, shock
- 10-20% mortality even with treatment
86
How to Dx malaria
- microscopy (thick and thin blood smears) - can determine species and parasitemia (% of RBCs infected)
* a negative blood smear does NOT rule it out
- rapid Ag tests - easy, cannot always speciate or determine parasitemia, can have false (-)
87
Malaria Treatment
- if uncomplicated - artemether-lumefantrine oral OR atovaqune-proguanil (artemisinin-based combo therapy - ACT)
- quinine and doxy/clinda in Canasa
- chloroquine (if sensitive area) and primaquine (gets hypnozoites dormant in liver)
- if severe - ACT, artesunate IV and doxy or clindamycin
- hospital admission
prophylaxis - mefloquine weekly
88
Big 3 Fever Viruses in Travellers
- presentations
- spread
- testing
- tx
- Dengue - diffuse blanching rash and petechiae
- hemorrhagic fever, shock
- serology
- Zika - conjunctivitis
- GBS, fetal microcephaly if in-utero
- PCR if under 10 days, serology
- no sex for 2 months (woman) or 6 months (male)
- Chikungunya
- persistent post-infectious arthralgia
- serology
- all present with fever, arthralgia, headache, rash, N/V/D
- aedes mosquito, biting occurs in the day, stagnant water in urban areas
- Tx - supportive care only
89
Typhoid
- salmonella typhi, fecal oral transmission (contaminated food and water)
- highest risk in south asia
- prolonged fever, fatigue, headache, apathy, bradycardia, leukopenia
- can lead to intestinal perforation, bleeds, sepsis
- CONSTIPATION IN ADULTS
- DIARRHEA IN KIDS
Dx- repeated blood cultures
Tx - ceftriaxone or azithromycin
- vaccine, but not 100% effective
90
Rickettsia
- intracellular bacteria, fleas/lice/mites/ticks
- various kinds of typhus and spotted fevers
Tx - doxycycline
