Travel medicine + Diarrhoea Flashcards
How many kids <5 die from diarrhoea each year
500,000
Most in SSA and india
How often do kids have diarrhoea each year
3 episodes per year
Peak at around 6-12 months (stop breast feeding and start crawling)
Name 3 risk factors for diarrhoea in children
Lack of breastfeeding 10x higher risk of mortality in <6m- Most important (and very cheap to fix)
Age: < 5 years, especially 6 18 months
Malnutrition
Immunosuppression
Measles
No immunizations
Lack of safe drinking water, sanitation and hygiene
3 categories of pathogens commonly causing diarrhoea in kids
Virus
rotavirus, norovirus - Top 2
[astrovirus , enteric adenovirus]
Bacteria
Shigella , Salmonella,
Campylobacter , diarrheagenic E. coli ,
Vibrio, Yersinia , Aeromonas ,
Plesiomonas
Parasites
Giardia , Crysptosporidum ,
Microsporidium , Cyclospora , Isospora ,
E. histolytica
What test is sensitive for bacterial diarrhoea
> 50 fecal leucocytes
-This indicates inflammation = likely bacterial
Key test in resource-poor places
Osmotic vs secretory
Secretory - has a toxin -> pulls water and electrolytes out
Osmostic - eg rotavirus
The most common cause of diarrhoea in kids <1 and globally <5 cause of death
rotavirus - 30% of deaths from diarrhoea
Types of E coli
ETEC - Enterotoxigenic E. coli
EPEC - Enteropathogenic E. coli
EIEC Enteroinvasive E. coli
STEC or EHEC Shigatoxin producing or EEnterohemorrhagic E. coli
EAEC - enteroaggregative E coli
Which e coli common to present with prolonged / chronic diarrhoea in kids
EPEC - Enteropatogenic E. coli
[E Paediatric/Prolonged]
Which e coli most common in travellers
ETEC - High volume watery diarrhoea
Entrotoxigenic E. coli (toxin similar to cholera toxin)
[E Traveller]
Which E coli is common in HIV and causes a biofilm
EAEC - Enteroaggregative E. coli
-As adheres can have prolonged infection
[Aggregates on itself and makes biofilm]
Which E coli produces shiga-like toxin -> bloody dysentery
EHEC (also called STEC - Shiga toxin-producing E Coli)
Especially 0157 strain
->HUS 10%
[oH HEC its the bad one]
Which are key pathogens for acute watery vs prolonged vs bloody vs dehydrating diarrhoea
Acute watery diarrhea :
rotavirus, norovirus, Cryptosporidium , ETEC, EPEC, Shigella , Campylobacter , Salmonella
Prolonged or persistent diarrhea :
EAEC, EPEC, parasites (coccidia
Bloodydiarrhea :
Shigella , Salmonella,
Campylobacter , STEC
Dehydrating diarrhea : Most important
rotavirus, ETEC, Cholera
[REC]
Good cheap test for shiga-like toxin
Latex agglutination test
Lots of coloisation in stool samples. How do you differentiate between colonisation and infective cause
PCR quantification (number of copies of DNA)
3 critical signs of dehydration
Thirst
Sensorium: irritable or comatose
Skin turgor: slow, very slow
-Best to do on abdo
[Sunken eyes, dry membranes, absent tears]
Mild vs mod vs severe dehydration in kids? Rx
A - Education and ORS
B - needs 100ml/kg in 6 hours
C - IV 20ml/kg if shocked, or 100ml/kg Oral in 6hrs
Key 3 measurements dehydration
Weight loss, blood pressure, urine output
Why do you not bolus Ringers lactate / polyelectrolyte solutions
Cant bolus stuff with K+ in
Key supplement for kids who have diarrhoea?
Zinc if >6m
- reduces symptoms and length
- prevents diarrhoea
What would make you want to use Abx in childhood diarrhoea
Fecel leucocytes > 50
Fever + bloody diarrhoea
Main causes of dehydrating diarrhoea
Rota, ETEC, Cholera
Explosive, watery (5-10 episodes day ), dehydrating diarrhea
Vomiting
Fever
Most likely? Key age group?
Rotavirus at 3-24months
[almost 100% have antibodies by 5 years]
[Norovirus second]
Rotavirus Dx?
Clinical usually
Rapid test Eg Latex agglutination / ICT
PCR
-Used if severe / outbreak / immunocompromised…
[Testing usually to prove its a viral illness -> avoid Abx]
Why rotavirus rare <3m
IgA from breast milk
rotavirus prevention
oral vaccine
Water and sanitation
Differentiate rota and noro in children clinically
Duration
Noro - <3 days
Rota - 5-8 days and slightly more severe
Both more in winter but:
-Rotavirus almost no cases in summer
-Noro all year round
How long excrete norovirus ? Issues with this?
several weeks
False positive tests down the line
Remain infectious
Most common cause of foodborne gastroenteritis outbreaks worldwide? - what is the classic foodstuff
Norovirus
Oysters
Why norovirus outbreaks in hospitals
Survive chlorhexidine / alcohol
Why norovirus outbreaks in hospitals
Survive chlorhexidine/alcohol
2 viruses which are similar to rotavirus but less severe? Diagnosis of these?
Adenovirus
astrovirus
Stool ELISA
What is genus shigella actually part of ?
E coli
Which shigella causes epidemics? Which common in India? Which in the industrialised world ? Which is most common? Which has most resistance? Most severe?
- S dysenteriae - epidemics and severe
- S boydii - india
- S sonnei - industrialised and most resistance
- S Flexneri - most common 70% of cases
What 2 dietary supplements are shown to reduce the incidence of dysentery
- Zinc
- Vit A
What produces shiga toxin? What complication may develop?
- Sh dysenteriae serotype 1
[Also produces a neuro toxin -> CNS]
HUS in around 15% of cases
Shigella incubation
1-5 days
[not less than 24hrs]
Shigella dx?
- Stool culture - need 2
- Fecal leukocytes helpful
Shigella rx? Second line?
- Most ok with ORS
- Ciprofloxacin (or another quinolone first line)
- Azithromycin
Shigella prevention
- Hygiene and sanitation
- Especially hand washing when preparing food
Only living reservoir for shigella and cholera?
Humans
[cholera - also water..copepods]
2 parts of cholera toxin and effect
- B - Binds to epithelial cells and allows entry of A
- A - increases cAMP and causes secretion of chloride by crypt cells -> diarrhoea
Cholera shape and stain
Gram -ve comma shaped bacilli with flagella
Which 2 cholera sero groups cause infection? Incubation?
- 01 and 0139
- Most outbreaks are 01 form
14hrs to 5 days
Rx of cholera ? Which abx can be used in severe cases?? What do Abx do?
- Fluid therapy
- Azithro / doxy
Don’t improve mortality
-Reduce volume of stools and transmission
-> require less resource for management
Cholera control strategies
- Early detection and isolation
- Contact tracing of household
- Longer term - improve water supply
- Oral cholera vaccines - Variable protection (Shanchol)
How to make ORS if you dont have it
1/2 teaspoon of salt
6 tea spoons sugar
1L water
Which group have high rates of shigella
Men who have sex with men
When not cipro for shigella
Asia (commonly resistant)
-> ceftriaxone
Cholera key implicated foodstuff for infection
shellfish and crabs
Cholera key implicated foodstuff for infection
shellfish and crabs
Obvious risk factors for cholera such as age, malnutrition but what blood type and which infection also implicated ?
Blood group O
H pylori
reduced gastric acidity
What factors affect cholera in water ? Specifically where in water does cholera live?
Temp, pH, salinity, sunlight - eg el nino
Grows in alkaline conditions
Lives next to phytoplankton - uses this for nitrogen
Which medium required for isolation of cholera
TCBS
Thiosulphate-citrate bile salts-sugar agar
green coloured medium with shiny yellow cholera colonies
2 main serotypes of 01 cholera
El tor
-Survives better in environment and causes less severe disease
Classical biotypes
-Endemic in Bangladesh only
more severe
Most sensitive clinical finding correlating with severe dehydration eg cholera
Character of radial pulse
What extra findings in Kids with cholera
Fever seizures and coma more predominant
HypoK, HypoNa, HypoGly more common
When IV fluid choice in cholera? over how long should you initially give resus fluid
Severe dehydration
Not tolerating PO
Ringer’s lactate
Rehydrate over 4 hours ~100ml/kg
Which country has 90% of cholera at the minute
yemen
What causes typhoid? what is it called when you develop septicaemia?
Salmonella enterica serovar typhi (salmonella typhi)
Gram negative bacilli
Enteric fever
Typhoid incubation? Common sx? Complications?
3 days - 2 weeks depending on inoculation load
High fever, variable systemic unwell, often consitpation
Rose spots
Paradoxical normal HR / brady despite the fever
GI bleeding, perf, pneumonitis, hepatitis - usually after 3 weeks
Typhoid dx? if poor facilities for this?
Blood culture
Widal agglutination test - measures antibodies to somatic (O) and flagellar (H) antigens
- not sensitive or specific
[Stool culture / bile/bone marrow aspirate]
Who gets big bilirubin rise in typhoid?
G6PD
Typhoid / paratyphoid rx? 2nd line?
-Cipro 1st line
[Azithro/Ceftriaxone - especially if high MDR area Eg India Pakistan]
Meropenem if really sick
Chronic typhoid carriers tend to have salmonella living where? Important long term risk?]Rx?
Gall bladder -may cause chronic cholecystitis/gallstone disease
-Risk of biliary Ca
Cipro - excreted in bile [+ high concentrations in the bowel]
Which salmonella has a vaccine? significance?
S typhi
Paratyphi causes 50% of infections in asia
Typhoid from where might end up with meningoencephalitis
Indonesia/India
Typhoid bloods
Leukopenia
Eosinopenia
Mild derranged LFTs
Typhoid resistance to what means you cant Rx with cipro
Nalidixic acid
Typhoid then 3 weeks later pain in RLQ what are you worried about
Ileal perf
Most effective typhoid vaccine
Conjugate vaccine
Shigella classic presentation
Classical presentation: watery diarrhoea for 1-2 days, then visible blood - but not massive volumes of stool
[In reality - only 40% are actually bloody]
Shigella transmission?
Direct contact faecal oral
-Often from mum
Very low infectious dose - 200 bacteria only
Key risk factors for severe shigella
Infants and adults > 50y
Children who are not breastfed
Children recovering from measles
Malnourished children and adults
History of seizures - 10% have seizures
Key complication of campylobacter
Guillain barre
2 main species of campylobacter
C Jejuni
C Coli
Campylobacter reservoir
Poultry
[Pig]
Campylobacter vs Shigella usual age in kids
Campy - first year of life
Shigella - Second year
Campylobacter Rx
Azithromycin
Campylobacter Dx
Stool cultures at 42 degrees
Diarrhoea then 4 days later reduced urine output and pale looking what are we worried about? key features ?
HUS
Thrombocytopenia
Anaemia
Renal failure
If the child presents with bloody diarrhea without fever key dx? what should you do?
STEC/EHEC (same thing)
NOT prescribe abx
If STEC/EHEC -> likely to augmented toxin production
Case 1: 10 month old girl with 1 day of diarrhea with blood, 3 stools/day and fever.
Case 2: 3 year old boy with 2 days of diarrhea with mucus and blood, 7 stools/day, abdominal pain and fever.
Case 3: 6 year old boy with 4 days of diarrhea with gross blood, 6 stools/day, intense abdominal pain and no fever.
1 - Campylobacter as <1year
2 - Shigella
3 - STEC (bloody diarrhoea and no fever)
Most common cause of fever in returned travller
Malaria - P falciparum most likely
Fresh water exposure risk of (2)?
Leptospirosis, Schistosomiasis
Exposure to rodents risk of? name 3
Hantavirus,
Lassa fever and other hemorrhagic fevers,
plague,
rat-bite-fever,
murine typhus
3 risks with unpasturised dairy products
Brucellosis, salmonellosis, tuberculosis, Q fever, listeriosis
Sea food and fish, raw or undercooked risk of?
Clonorchiasis, paragonimiasis, Vibrio, hepatitis A, gnathostomiasis, adenocephalus pacificus/dibothriocephalus latus
Raw meat risk of?
Trichinellosis, salmonellosis, E.coli O157, campylobacteriosis, toxoplasmosis, gnathostomiasis
Raw vegetables, aquatic plants (watercress), snails risk of?
Fasciolasis, fasciolepsiasis, angiostrongylosis
Classic examples of a biphasic (saddleback) fever?
Dengue, YF, leptospirosis
What do these signs mean? (rule in of)
Eschar:
* Chancre:
* Rose spot:
* Symmetrical arthritis of small joint:
* Conjunctival suffusion:
* Rash and conjonctivitis:
* Rash « White island on a red sea »:
* Anosmia:
Eschar: Rickettsiosis
* Chancre: syphilis, trypanosomiasis
* Rose spot: Enteric fever
* Symmetrical arthritis of small joint: Chikungunya
* Conjunctival suffusion: leptospirosis
* Rash and conjonctivitis: Zika
* Rash « White island on a red sea »: Dengue
* Anosmia: COVID-19
Trip in India, Nepal, Pakistan, Bengladesh
High fever, abdominal pain, relative bradycardia = ?
Enteric fever
Fresh water exposure in Malawi Lake
Fever, eosinophilia, hepatomegaly
Katayama fever
Mosquito bite in urban areas in tropical country
Fever, headache, myalgia, retroorbital pain, rash, thrombocytopenia
Dengue
Rafting, Thailand
Fever, myalgia, conjunctival suffusion icterus, rash
leptospira interrogans
Forest in central Europe
Fever, ALC, paralysis
Tic bite encephalitis
Back from a trip to subsaharian Africa Amazon, non vaccinated
Hemorragic fever, icterus, kidney failure, proteinuria
Yellow fever
Trip in south Africa, safari
Fever, eschars
African tick-bite fever (Rickettsia africae)
Name 3 risk factors for travellers diarrhoea
Daily use of a proton pump inhibitor
Low-budget or adventure travel
O blood type
Travel from an industrialized country to a developing/tropical
Age
* Being a toddler or adolescent
Lack of dietary discretion
No previous travel to a developing region
Localised infection with fever - which organ systems are usually bacterial
Gastrointestinal: 80% bacterial
Genitourinary : >90% bacterial
Cutaneous : >90% bacterial
Undifferentiated fever in Asia, Africa, and south America key causes?
In rural or urban areas where do kids have more fevers? What type of pathogen?
Rural especially if even younger
-Usually viruses (hard to diagnose without access to serology in rural settings too)
Key investigation in all with fever in Tropics
HIV test
3 Rs of vaccines
Routine - ?need updated
Required - Eg yellow fever regulations
Recommended - risk is behaviour related
Types of vaccine
Replicating virus vaccines
– Replicate in vaccines; longer-term immunity
Killed viruses/recombinant protein-often multi-dose
– T-cell memory; long-term immunity
Bacteria
– Always short-term protection
Polysaccharide
– Now conjugated to protein to induce T-cell
memory, booster effect, increased protection.
mRNA: naked encapsulate or viral vector
Routine vaccines- name 5
Tetanus/diphtheria/pertussis
* Measles
* Polio
* Pneumococcal
* Varicella
* Influenza (separate lecture)
* HPV, Zoster
what is the most common vaccine preventible disease in travellers
Influenza
How long does flu vaccine last?
6 months
(decreases by about 9% per month)
Diptheria vaccine also has? Primary series? when booster?
Tetanus/Diphtheria/Pertussis [Tdap vaccine]
Primary series: 0, 4 wk, 6 months
Booster after 10 years
Measles - who is immune? Doses for protection? given with?
Born before 1957 = immune
2 doses - usually 12-15 months & 4-6 yr
Measles Mumps Rubella
Varicella zoster, doses for protection? booster?
2 doses
No booster
Which vaccine for shingles which is given to people > 50? What is they’ve had shingles? What if immunocompromised?
Shingrix
Given 2 doses usually around 2 months apart
Wait 1 year then give the vaccine series anyway
CD4 >200, otherwise decision with a consultant (usually give)
Which polio is responsible for the ongoing infections
WPV1
Which is ideal pneumococcal vaccine
PVC 20
Immunocompromised how can you cover for hep A
Give HepA Ig - lasts 2 months
-If won’t mount response to vaccine
How many doses for HepB
3 doses (0, 1, 6m unless using accelerated series)
[New expensive Heplisav-B is only 2 doses over 1 month]
Which HepE geneotype is bad?
GENOTYPE 1 and 2 - 20% mortality in pregnant women
Which vaccine still kills 1/250,000 people? Whos at risk?
Yellow fever
People with thymus disorders
Who needs yellow fever booster
HIV, travel to west Africa
Key meningitis geography risk ? What season?
Belt across Africa from Senegal/Gambia to Somalia
Dry season December-June (due to dry mucus membranes)
Which meningitis vaccine only once licenced for kids
Menveo
Important side effect of meningitis vaccine
Gillian barre
Key people requiring specific MenB vaccine
Asplenia / complement deficiency
Who gets cholera vaccine ?
Aid and refugee workers
Oral vaccine
Which bacteria does cholera vaccine also work against
ETEC - has b subunit as well
Who gets rabies PrEP ? What does it do? How many doses?
High-risk researchers.
long-stay travellers to high risk areas - eg rural adventure
Prevents need to get rabies Ig if exposed
2 doses day 0 and 7
They STILL NEED rabies vaccine
Who needs rabies Ig?
Non-primed - eg 2 doses and >3yrs later
[If you’ve had 3 doses - you are good for life]
Also get 4 doses of the vaccine [5th dose if immunocompromised AND titres degative after 4]
Japanese encephalitis reservoir? Breeding site? Number of vaccines?
Pigs
Mosquitos breed in rice paddy’s
2 vaccines 28 days apart - last 1 year
Booster after 1 year - Lasts 10 years
Tick-borne encephalitis Vaccine number of doses
3 doses over 5-12 months
Which vaccines have egg
yellow fever, measles, mumps, flu
Which vaccines contain neomycin
measles, mumps, rubella,
varicella
Which vaccine contains streptomycin
Oral polio vaccine
which vaccines do you not give in pregnancy
Generally just the ones you don’t give to immunocompromised
You Musn’t Prescribe BCG Incase They RIP Stat
MMR, varicella, Ty21a, live influenza, HPV
Killed influenza wait till 2nd trimester in
many countries
Antimalarials contraindicated in pregnancy
Doxycycline, Malarone, Tafenoquine Primaquine
DMTPeople
[Artemisinins actually fine]
Acetazolamide in pregnancy
NOT Safe
Breast feeding which vaccine big big contraindicated
Yellow fever
Which ART class most interactive with antimalarials? Which antimalarial worst
protease inhibitors most problematic ART drug.
mefloquine is the most problematic;
3 vaccines recommended for all travellers
Typhoid
HepA
HepB
which meningococcal strain is not in the primary series vaccine
B
[Men ACYW]
2 complications of flu vaccine
Egg allergy
Gillian-barre
Name 3 complications of PID
Infertility
Chronic pelvic pain
Ectopic pregnancy
PID rx
Cef + doxy + metronidazole
Gonrrhorea / chlamydia rx
Gon - Ceftriaxone
Chlamid - Doxy
Mycoplasma genitalium rx
Doxy + azithro/moxifloxacin
Gonococcal vs reactive arthritis
Gonococcal
-Tendosynovitis
-Migratory polyarthritis
- Rash which may pustulate
Reactive
-Tendosynovitis rare
- Rash affects palms / soles
Difference between immigrant and refugee
Immigrants choose to move,
whereas refugees are forced to flee
Name 5 things you could screen for in a refugee
Which migrants should get varicella vaccine?
All kids <13
Screen if >13 and vaccinate if no antibodies
name 2 conditions VFRs have in particularly high rates when compared with other travellers
malaria, hepatitis A and typhoid
Most common deficiency worldwide
Iron
