Imported Fevers Flashcards
Key elements of a travel history
- where did you go? (be as exact as possible, include stop-overs, rural vs urban)
- when did you go? (exact dates and timings of symptoms; ask first about last few weeks and then last few years)
- why did you go? (VFR - visiting friends and relatives?)
- what did you do? (activities / interactions)
- what pre-travel vaccines/malaria prophylaxis did you take?
When do malaria symptoms present?
falciparum: within 1 month (7d - 3 months)
non falciparum: some months after (weeks to months)
Areas with viral haemorrhagic fever?
sub saharan africa
Areas with malaria
SSA
latin america and caribbean
south east Asia
central and South Asia
Incubation period of viral hemorrhagic fevers
3-21 d
most people develop Sx within 7-10d
VHF
viral hemorrhagic fevers
Ways to get exposed to tropical diseases?
ticks
animals
tsetse fly
cruise ships or resorts
freshwater
game park
inhalation of dust or faeces
sexual contact
contaminated food or water
raw food
unpasteurised milk
bush meat
MERS mortality in relation to sars-cov-2 and associated animal
much higher mortality
from camels
% poeple returning from SSA with tropical illness?
70%
What type of travel is at higher risk of tropical infections?
What infections are common from returnees in SE Asia?
- Risk of tropical infection higher among VFRs (visiting friends and relatives)
- Non-tropical were common among returnees from SE Asia (45%)
- but enteric fever (34%) and dengue (20%) remain important
why are VFRs ar high risk of tropical infections?
may be in more rural areas
may not be as careful with prophylaxis
may think they have immunity but this immunity may have disappeared after not being in the country for some years
Risk assess for VHF
VHF within 21d of return
also check for malaria
undifferentiated fever
fever without focal signs where the fever could be coming from
RDT for malaria
now increasingly used
rapid tests
Paracheck-Pf® (detect plasmodial HRP-II)
OptiMAL-IT (parasite LDH)
falciparum malaria on smear
‘headphones’ - 2 black dots connected
more than one parasite in one RBC
Management of severe falciparum Malaria
IV artesunate
parasitaemia - why is it important to know in malaria?
will tell you if it is severe or not
which group is mainly affectedly deaths from malaria?
African children <5 account for 80% of all malaria deaths in the region
Malaria with greatest mortality
Plasmodium falciparum
Plasmodium vivax
the most common of the less virulent (non-falciparum) species
causes milder disease
dominant in endemic areas outside SSA e.g. southeast asia
causes tertian malaria (fever spikes every 48h)
plasmodium falciparum
most virulent and causese the most severe disease
dominant in Africa
commonest type of malaria
life cycle of malaria
Mx of malaria caused by P.vivax and P. ovale
chloroquine + primaquine (check G6PD first before giving primaquine)
Prevention and pre-travel advice in malaria
risk assess - geographical + individual (pregnancy/accommodation/season)
prevent mosquito bites (repellants/nets)
prophylaxis (malarone/mefloquine/doxycycline; varies by region)
Presentation of malaria
10-15d post bite in
cyclical fevers
chills, high fevers and sweats
What gives you a dx of severe malaria?
high parasitaemia (>2% // >5% in non immune or >10%) OR schizont
- altered consciousness with or without seizures
- respiratory distress or ARDS
- circulatory collapse
- metabolic acidosis
- renal failure, haemoglobinuria (blackwater fever)
- hepatic failure
- coagulopathy +/- DIC
- severe anaemia or massive IV haemolytic
- hypoglycamiea
Why not give too many fluids in malaria?
???
Schizont
RBC with multiple parasites in it
one schizont give you a diagnosis of severe malaria
Thick and thin blood smear
Field’s or Giemsa stain
Thick: screen parasites (sensitive)
think: identify species and quantify parasitaemia
Malaria antigen detection tests
Paracheck-Pf (detect plasmodial …)
OptiMMAL-IT (parasite LDH)
Management of malaria
Falciparum:
- severe: 1. artesunate IV 2. quinine IV
- mild: oral ACT (Riamet/Co-artem - artemisinin combination therapies, eat with fatty meals)
Non-falciparum
- chloroquine + primaquine (check G6PD)
Mx of severe malaria
ABCDEFG (correct hypoglycaemia, cautious rehydration avoiding overload, organ support)
IV artesunate In preference to IV quinine
Daily parasitaemia then PO follow on eg with ACT (artemesin combination therapy (riamet - Artemether + lumefantrine)
SE of IV quinine
cinchonism
arrhythmia
hyperinsulinaemia
SE of IV artesunate
delayed haemolysis (make sure to FU a few weeks after treatment!!)
What should you check before starting chloroquine + primaquine?
G6PD
otherwise can get severe haemolysis
What is dengue transmitted by?
Aedes mosquito
mainly: Aedes aegypti
How many seroptyeps of dengue?
4 (1-4)
where does dengue replicate?
midgut
prevention of dengue
use mosquito repellents
cover your skin (long sleeves, nets etc)
in people who have had dengue before: vaccination
climates with dengue
urban and semi urban
tropical and subtropical climamtes
early morning and dusk/twilight -> cover skin particularly then
Vaccine: Dengvaxia (licensed 2015, not for travellers, only for people who have had dengue before)
mosquito control (on a governmental etc level)
how many dengue cases of dengue in UK / year
340
NOTIFIABLE
Dengue incubation and disease duration
4-7 d incubation
duration 2-7 dy
sx of dengue
high fever (40)
severe headache (retro-orbital)
myalgia/arthralgia
N&V
blanching rash (sunburn, white when you press)
Maculopapular, measles-like exanthem (2-5d post fever onset)
thrombocytopenia
Most are mild/ asymptomatic – get better in 1-2 weeks but can be severe
testing for dengue
blood/urine PCR (after 4 days)
serology after 5-7d
- IgM: (cross reacts with other viruses
- IgA can be useful
- IgG not very useful
convalescent serology 2w later to check
RDT (rapid diagnostic tests - Not the best yet)
issues with dengue serology
X-reaction with other flaviviruses IgG (JE, yellow fever)
have to wait 5-7d to do serology
Vaccines for dengue
Dengvaxia
licensed in 2015
not for travellers
Figmothermic bradycardia
fever with no tachy / fever with bradycardia
Himalaya peak temperatures - which pathogen and what are they ?
typical of salmonella typhi
temperature goes up and down
What causes enteric fever?
salmonella typhi and paratyphi
transmission of enteric fever
faeco oral (only humans can be infected, no known animal reservior, some humans can be carriers (Typhoid Mary))
Diagnosis of typhoid fever
blood, BM and stool cultures
RDT - false +ve, used in low income settings only
where is enteric fever common?
10x more likely on Indian subcontinent
Clinical presentation of enteric fever
gradual onset of high, prolonged fever
headache
rose spots (rare)
constipation
dry cough
untreated typhoid course
week1: fever, fluctuations with bradycardia, malaise, headache, cough, epistaxis
week 2: extreme fatigue, high fever and plateau, bradycardia, delirium, raised ALT, HS-megaly
wee 3: complications: intestinal haemorrhage due to bleeding, congested Peyer’s patches, intestinal perforation in the distal ileum, septicaemia, resp complications, encephalitis
Which mosquito spreads malaria?
female Anopheles mosquito
Fever in a returning traveller - causes
- tropical diseases (e.g. malaria, typhoid, dengue, VHF; bacterial disease e.g. cholera, E.coli)
- common UK causes (UTI, Pneumonia, influenza)
- STIs (e.g. HIV seroconversion)
Resource to check for current outbreaks
Promed
NaTHNaC / travel health pro
Which type of salmonella is only seen in humans?
S. Typhi
it is NOT zoonotic
the only reservoir is in humans
What are the different types of salmonella?
typhoidal
- S. typhi
- S. paratyphi
Non-typhoidal
- S. enteritidis
- S. cholerasuis
- S. typhimurium
What type of pathogens are salmonella species?
What do they produce on a certain growth medium?
anaerobic gram -ve bacilli
produces H2S (hydrogen sulfide) on TSI agar
how long does S. typhi vaccination last for?
3 years
Who is the S. typhi vaccination recommended for?
traveling to high-risk areas (East and Southeast Asia, South and Central America, Africa
How does typhoid fever present?
Incubation period: 6-30d
Week 1
fever fluctuations
Relative bradycardia
Constipation or diarrhea
Headache
dry cough
Week 2
Persistent high fever (no chills) and plateau- mostly unresponsive to antipyretics
Rose-spots (lower chest and abdomen) - 1/3
raised ALT
EPISTAXIS (in 25%)
Typhoid tongue: greyish/yellowish-coated tongue with red edges
Nonspecific abdominal pain and headache or RLQ pain (terminal ileum)
Yellow-green diarrhea, or obstipation and bowel obstruction (as a result of swollen Peyer patches in the ileum)
Neurological symptoms (delirium, coma) -> due to
Week 3
Clinical features of week 2
Additional possible complications include:
Gastrointestinal ulceration with bleeding and perforation
Hepatosplenomegaly
In rare cases: sepsis, meningitis, myocarditis, and renal failure
From week 4 improvement (or complications)
What pathogen causes enteric fever?
S. typhi
Pathophysiology of typhoid fever.
- high infective dose (10^5 organisms) needed to cause disease (ORAL uptake)
- uptake by Peyer’s patches in the distal ileum (migrates via M cells through the epithelium and into the Peyer patches)
- Infection of macrophages → nonspecific symptoms (can survive IC -> facultative IC parasite with flagella)
- Spread from macrophages to the bloodstream → septicemia → systemic disease
- Migration back to intestine → excretion in feces
transmission of salmonella
faeco-oral
S. typhi humans are the only reservoir
for other types can also get if from raw eggs/undercooked chicken
food prepared buy carriers
contaminated water
Prevention of typhoid fever?
- Sanitation & hygiene
- Vaccination – partially protective for S.typhi but no cover for S. paratyphi
Mx of typhoid fever
ORS (oral rehydration solution)
First Ceftriaxone IV
Then give Azithromycin PO
(depending on resistance)
Complications of typhoid fever
- GI perforation
- septicaemia as a result of perf
- encephalitis
- respiratory complications
- 2-5% Chronic salmonella carrier (increased risk of gallbladder cancer)
Why is chronic carriage of salmonella an issue?
increased risk of gallbladder cancer
Ix for typhoid fever
blood and stool cultures
FBC
LFTs (raised ALT)
Distinguishing feature of enteric fever
Sphygmothermic dissociation (relative bradycardia)
+ fluctuating fever which then plateaus (not very responsive to antipyretics)
Who is at increased risk of salmonella?
people with SCD/asplenic patients
- are at increased risk of salmonella infections
- can get salmonella osteomyelitis
areas where travellers can get enteric fever from
tropics & subtropics
distinguishing feature of anopheles mosquito
the only one that feeds with thorax in the air
What are arboviruses and what are some examples?
viruses spread through can anthropod vector such as a mosquito (blood sucking)
RNA viruses
e.g. West Nile virus; Chikungunya; Zika; Dengue;
subtypes of arboviruses
bunyaviridae (e.g. hantavirus, rift valley fever)
togaviridae (e.g. chikungunya)
flaviviridae (e.g. dengue, yellow fever, zika)
Do you have to isolate someone with dengue?
no because you get it via mosquitoes
is dengue notifiable?
yes
Leptospirosis - which animal associated with?
rats
Issue with dengue reinfection
risk: dengue haemorrhagic fever/dengue shock syndrome if infected with different serotype
Antibody dependent enhancement is the underlying mechanism
you get cytokine storm
rarely seen in travellers
Mx of dengue
supportive
generally self limiting in 1-2 weeks
Do travellers get dengue haemorrhagic fever?
generally no
they can get dengue but DHF is uncommon
Do travellers get dengue haemorrhagic fever?
generally no
What happens with a sample that you take with ?dengue/other tropical diseases?
gets sent to RIPL (rare and imported pathogens laboratory)
there they test for everything from the area the patient travelled to
you still give them some clinical information and what you suspect so that they can interpret the findings accordingly
Why is dengue associated with water?
because mosquitoes (aedes) are found near water
which blood bottle for malaria thick and thin films
EDTA (purple)
Features of severe falciparum malaria
(RELEVANT FOR FINALS)
Impaired consciousness (GCS<15) or seizures
renal impairment
acidosis (pH <7.3)
hypoglycaemia (<2.2 mmol/L)
pulmonary oedema or ARDS
anaemia (Hb <8g/dL)
spontaneous bleeding/DIC
shock (BP <90/60 mmHg)
haemoglobinuria (without G6PD)
parasitaaemia >2% (WHO >10%)
pregnancy
vomiting
what pathogen type causes malaria
plasmodium
= protozoal infection (unicellular eukaryotes)
Life cycle of plasmodium (malaria)
involves mosquitoes (female anopheles) and humans (RBCs and liver; initial replication in liver then asexual reproduction in RBCs)
In humans: Erythrocytic and
Exoerythrocytic stages
Undergo asexual reproduction in the erythrocytes
Features on microscopy of different plasmodium species
Falcip – double dotted rings (chromatin dots on some rings)
Vivax – schuffners dots may be present
Malariae – mature schizonts have daisy head appearance. Squarish appearance of ring forms
Ovale – enlarged red cells. Comet forms
P. knowlesi
return from tropics, sunburn rash, low platelets, fever - dx?
dengue
Malaria disease course
Infection → asymptomatic parasitemia → uncomplicated illness → severe malaria → death
Which drug is used to eradicate
liver hypnozoites in P. vivax and
P. ovale malaria?
Primaquine
The Plasmodium species associated with dormant hypnozoites in the
liver are….
Plasmodium vivax
Plasmodium ovale
Which patients are relatively resistant to malaria?
sickle cell trait
What are dormant malaria plasmodium stage in the liver called?
hypnozoite
what pathogen causes anthrax? what type of pathogen is it
bacillus anthraces
gram-positive spore-forming bacterium
Mx of anthrax
doxycycline / ciprofloxacin
Signs of anthrax
pulmonary: massive lymphadenopathy + mediastinal haemorrhage
cutaneous: painless round black lesions + rim of oedema
SE of RIPE
Rifampicin - orange secretions, raised ALT (if 5x upper normal stop, if 3x then monitor and continue)
Isoniazid - peripheral neuropathy
Pyrazinamide - hepatitis
Ethambutol - ophthalmoplegia, loss of colour vision (check CV before starting)
what is a marker of someone with TB being infectious?
+ve auramine stain of sputum
why are AFB test positive in TB?
they have a mycolic acid layer
in the test they are heated up, stain gets in and as the layer forms again the stain does not leave
in organisms without this layer the stain simply gets out
Mx of latent TB
R+I for 3 months
OR
isoniazid for 6 months
What if someone on TB meds is not getting better?
have a high level of suspicion for ddx
usually people respond well to anti-TB meds
also check for resistance
common types of extra pulmonary TB
LN
CNS
peritoneal
in what TB cases should you add prednisolone for treatment and how long?
CNS and pericardial TB
high dose pred for 6-10 w
imaging in TB
CXR initially
often CT scan is useful
what are the issues with strep pneumoniae blood cultures?
S. pneumoniae undergoes autolysis
additionally the best time to take blood culture is 1h before onset of fever and this would rarely be done
What % people have Staph on their skin and what % of that is MRSA?
20%
20% of them
mortality of S aureus sepsis
30-40%
how caan you get Staph aureus sepsis?
IVDU
cuts/grazes
diabetic foot ulcers
psoriasis
name g-ve rods
E coli
Klebsiella
citrobacter
How long after TB Mx is initiated are patients hopefully no longer smear +ve and infective?
2w
clinical presentation of chikugunya
Fever
!!joint pain (severe bilateral polyarthralgia)
periarticular oedema
headache
maculopapular 089 rash
How can you get chikungunya>
Aedes mosquito (aegypti > albopictus).
Vertical
causative agent of chikungunya and pathogen type
CHIKV.
Genus: Alphavirus of Family Togaviridae. RNA
Mx of chikungunya
Mainly supportive.
Simple analgesics (paracetamol/ NSAID) but avoid aspirin.
Ix for chikungunya
PCR or IgM
What confection can you get in chikungunya?
dengue
both by aedes mosquito
complications of chikungunya
Main is severe chronic arthralgia for weeks/ months
Where is chikungunya seen
Widespread Africa, Americas, Asia
Where is chikungunya seen
Widespread Africa, Americas, Asia
incubation period for chikungunya
Inc: 3-7 days
(range 1-10)
Which infections are associated with Guillain Barre syndrome?
Campylobacter jejuni
Zika
CMV
influenza
EBV
HIV
Where are VHF mainly?
SSA
Mx of leptospirosis
Antibiotics: doxycycline, ceftriaxone, penicillin
Mx of Strep pneumonia sepsis
PENICILLIN
as high a dose as you can e.g. 12g/d BenPen
Ix for leptospirosis
PCR of DNA in serum, urine, CSF
IgM ELISA (false positive with EBV, CMV, viral hepatitis)
Epidemiology of leptospirosis
Tropical, subtropical & temperate
e.g. sewage/ after floods/ rural areas/ water sports
transmission of leptospirosis
excreted in dog/rat urine
can invade abraded skin or mucous membranes
penetrates broken skin
mouth/eyes/nose/wounds
swimming in contaminated water
What pathogen causes leptospirosis
zoonotic disease caused by gram-negative Leptospira bacteria (L. interrogans)
obligate, aerobic, motile spirochetes
many subgroups
can invade abraded skin or mucous membranes
Sx of leptospirosis
early phase: mild and characterized by nonspecific symptoms (e.g., high fever, headache, and myalgia (thighs and lower back))
second phase: meningismus and raised WCC in CSF, correlattes with IgM generation
CONJUNCTIVAL HAEMORRHAGES
Most cases -> symptoms resolve spontaneously after 1/52
10% of cases -> disease progresses rapidly to a severe form (icterohemorrhagic leptospirosis, or Weil disease), which typically presents with a triad of jaundice, bleeding manifestations (haemorrhages in organs), and AKI
+haemolytic anaemia
+mental status change
How do you get anthrax?
zoonotic infection
in: cows, goats, and sheep
transmission by contact with infected animals or infected animal products
Lyme disease - how do you get it?
e.g. hiking
transmitted via ticks (Ixodes scapularis tick) - anthropod-borne
or deer
Neuroborreliosis mx
IV ceftriaxone for 2-4w
Mx of Lyme disease
doxycycline for 2-3 weeks
or: amoxillin, cefuroxime, azithromycin
Lyme diseases dx
clinical (esp. if erythema migrans is present)
ELISA (sensitive) and Western blot (specific) antibodies for IgM (2-4 weeks) and IgG (4-6 weeks.)
PCR of blood/ CSF but imperfect.
vector for lyme disease
Ixodes scapularis
also: deer
What pathogen causes lyme diseases?
Borrelia spp. (spirochaete - bacteria)
e.g. burgdorferi in USA (other types more common in Europe and asia i.e. B. afzelii and B. garinii)
Presentation of lyme disease
Can be asymptomatic
Early localized infection: in 80% this is Erythema migrans rash – can be large and then clear centrally ‘bull’s eye rash.’ May have viral symptoms.
Early disseminated infection: through blood/; lymph – in 10-20% rah, myalgia, arthralgia. 10-15% untreated get neuroborrleiosis – lymphocytic meningitis, cranial neuritis, radiculopathy, mononeuritis multiplex
May cause heart Lyme carditis: palpitations, dizziness, fainting, HF
Late disseminated infection: after several months; multisystem. In 60% of untreated can lead to join pain/ effusions/ Lyme encephalopathy/ encephalomyelitis. ACA – Acrodermatitis chronica atrophicans
