travel related infection Flashcards
unfamiliar features of imported diseases
presenting features isolation requirements diagnostic methods treatment/management unexpected complications
vulnerability of travelers to infection
temptation to take risks away from home - food, water, animals, sex
different epidemiology of some diseases - HIV, TB, polio, diphtheria
incomplete understanding of health hazards
stress of travel
refugees - deprivation, malnutrition, disease, injury
common worldwide infections
influenza
community acquired pneumonia
meningococcal disease
STD
climate or environment related health problems
sunburn heat exhaustion/heat stroke fungal infections bacterial skin infections cold injury altitude sickness
how are infections controllable by public health measures
sanitation
immunisation
education
infections controllable by sanitation
traveller's diarrhoea typhoid hep A/E giardiasis amoebiasis helminth infections viral gastroenteritis food poisoning shigella dysentery cholera cryptosporidiosis
infections controllable by immunisation
poliomyelitis
diphtheria
infections controllable by education
HIV
STDs
water related infections
bathing in infected water
schistosomiasis leptospirosis liver flukes strongyloidiasis hookworks guinea worms
arthropod borne infections
mosquitos - malaria, dengue fever
mosquitoes - elephantiasis, filariasis
ticks - rickettsial infections, typhus
sand flies - leishmaniasis
tsetse fly - trypanosomiasis, sleeping sickness
black flies - river blindness, onchocerciasis
emerging infectious diseases
COVID 19 - global pandemic zika - latin america, caribbean ebola - west africa MERS-CoV - middle east swine flu - worldwide avian flu - china SARS: far east, worldwide west nile virus - US
important tropical diseases
malaria typhoid dengue fever schistosomiasis rickettsiosis viral haemorrhagic fevers
malaria epidemiology
most important imported disease
UK - 1400 cases p/a, 6 deaths p/a
worldwide - 207mln cases p/a, 627 000 deaths p/a
what cells does malaria effect
RBC
what areas of the world does malaria affect
tropics
subsaharan africa, northern parts of south africa, northern parts of south america, asia (indian subcontinent, SE Asia)
what is the vector for malaria
female anopheles mosquito
what are the 5 species of malaria
potentially severe: plasmodium falciparum
“benign”: P. vivax, P. ovale, P. malariae, P. knowlesi
symptoms of malaria
fever rigors aching bones abdo pain headache dysuria frequency sore throat cough
signs of malaria
majority show none at the beginning
splenomegaly
hepatomegaly
mild jaundice
complications of malaria
cerebral malaria (encephalopathy) blackwater fever pulmonary oedema jaundice severe anaemia algid malaria
cerebral malaria
non-immune visitors
children in endemic areas
hypoglycaemia
convulsions
hypoxia
potentially fatal
blackwater fever
severe intravascular haemolysis high parasitaemia profound anaemia hemoglobinuria acute renal failure
what is algid malaria
development of gram -ve septicaemia in those w/ malaria
malaria diagnosis
thick and thin blood films - giemsa, field’s stain
quantitative buffy coat (QBC) - centrifugation, UV microscopy
rapid antigen tests - optiMal, ParaSight-F
severity assessment
complicated malaria = one or more of:
impaired consciousness or seizures hypoglycaemia parasite count ≥2% haemoglobin ≤8mg/dL spontaneous bleeding/DIC haemoglobulinuria renal impairment or pH <7.3 pulmonary oedema or ARDS shock (algid malaria) - ? gram -ve bacteraemia
2 main drugs for malaria treatment
quinine
artemisinins
treatment options for uncomplicated P. falciparum malaria
riamet - 3 days
eurartesim - 3 days
malarone - 3 days
quinine - 7 days plus oral doxycycline (or clindamycin)
side effects of quinine
nausea tinnitus deafness (cinchonism) rash hypoglycaemia
treatment options for complicated or severe P. falciparum malaria
IV artesunate
IV quinine plus oral doxycycline (or clindamycin)
switch to oral treatments when pt is stable and able to swallow
side effects of IV quinine
cardiac depression
cerebral irritation
N+V
treatment of P. vivax, P. ovale, P. malariae, P. knowlesi
chlorquine - 3 days
riamet - 3 days
add primaquine (14 days) in vivax and ovale to eradicate liver hypnozonites
malaria control programmes
mosquito breeding sites - drainage of standing water
larvacides into the water - paris green, temphos, biological
mosquito killing sprays - DDT, malathion, dieldrin
human behaviour - bed nets, mesh windows
typhoid fever causative organisms
salmonella typhi
salmonella paratyphi
epidemiology of typhoid fever
global - 27mln infections p/a
>200 000 deaths p/a
UK - 500 cases p/a
how is typhoid fever spread
poor sanitation
unclean drinking water
clinical features of typhoid fever - week 1
fever headache abdo discomfort constipation dry cough relative bradycardia neutrophilia confusion
timeline for typhoid fever
incubation period - 7days-4wks
disease becomes apparent over next 4 wks
clinical features of typhoid fever - week 2
fever peaks at 7-10 days rose spots diarrhoea tachycardia neutropenia
clinical features of typhoid fever - week 3 (complications)
intestinal bleeding
perforation
peritonism
metastatic infections
what % of typhoid fever pts relapse
10-15%
diagnosis of typhoid fever
not easy
based on evolution of clinical features
laborator: culture blood, urine and stool, sometimes culture bone marrow
treatment of typhoid fever
oral azithromycin - drug of choice for asian-acquired, uncomplicated enteric fever
IV ceftriaxone - if complicated or concerned re absorption
dengue
viral infection
commonest human arbovirus infection
100mln cases p/a
25 000 deaths p/a
disease of the tropics
transmission of dengue
aedes aegypti mosquito
clinical presentation of dengue fever
sudden fever severe headache, retro-orbital pain severe myalgia and arthralgia macular/maculopapular rash haemorrhagic signs: petechiae, purpura, +ve tourniquet test
dengue diagnosis
clinical: thrombocytopenia, leucopenia, elevated transaminases, +ve tourniquet test
lab: PCR, serology
dengue management
no specific therapeutic agents
complications of dengue
dengue haemorrhagic fever (DHF)
dengue shock syndrome (DSS)
rx: IV fluids, fresh frozen plasma, platelets
prevention of dengue
avoid bits
new vaccine - limited use
schistosomiasis transmission
fresh water
freshwater snails
parasitic infection
schistosomiasis causative organisms
S. haematobium
S. mansoni
S. japonicum
schistosomiasis clinical features
swimmers itch (1st few hrs, clears in 24-28hrs) invasive stage (after 24hrs) katayama fever (15-20 days) acute disease (6-8wks) chronic disease
schistosomiasis invasive stage
cough
abo discomfort
splenomegaly
eosinophilia
schistosomiasis katayama fever
prostate fever urticaria lymphadenopathy splenomegaly diarrhoea eosinophilia
schistosomiasis acute disease
eggs deposited in bowel - dysentery
eggs deposited in bladder - haematuria
diagnosis of schistosomiasis
clinical diagnosis
antibody tests
ova in stools and urine
rectal snip
treatment of schistosomiasis
praziquantel 20mg/kg
2 doses 6 hrs apart
prednisolone if severe
rickettsiosis
tick typhus (R. conorii, R. africae)
rocky mountain spotted fever (R. rickettsii) epidemic typhus (R. prowazekii) murine or endemic typhus (R. mooseri) scrub typhus (R. tsutsugamushi) others
commonest form of rickettsiosis imported to the UK
tick typhus
from southern africa, mediterranean, arabian gulf
clinical features of rickettsiosis
abrupt onset swinging fever headache confusion endovasculitis rash - macular, petechial bleeding
diagnosis of rickettsiosis
clinical features
serology
management of rickettsiosis
tetracycline
viral haemorrhagic fevers examples
ebola
congo-crimea haemorrhagic fever
lassa fever
marburg disease
serious infections but rare in UK
management of viral haemorrhagic fevers
maximum incubation period 3 wks
rule out common severe infections
isolation - high security infection unit
supportive treatment
Zika
flavirus
related to dengue, yellow fever, Jap B encephalitis, west nile viruses
pacific outbreak 2013-14 latin america pandemic - 2015-16
how is zika virus transmitted
daytime biting Aedes mosquitoes
sexual contact
blood transfusion
clinical features of Zika
no or mild symptoms headache rash fever malaise conjunctivitis joint pains
like dengue
what can Zika infection in pregnancy result in
microcephaly
other neurological problems
what syndrome can Zika lead to
Guillain-Barre
management of Zika
no antiviral therapy
mosquito control measures
vaccines in development
most common cause of fever in a returning traveller
malaria
history for fever in a returning traveller
is it tropical travel hx precautions taken risks symptoms incubation periods
signs to look for in examination in fever in a returning traveller
rash - typhoid, typhus, dengue
jaundice - hepatitis, malaria, yellow fever
lymph nodes - leishmania, trypanosomiasis
liver - malaria, typhoid, amoebic abscess
spleen - visceral leishmaniasis, typhoid, malaria
investigations for fever in a returning traveller
FBC malaria films LFTs stool microscopy and culture urine analysis and culture blood cultures CXR specific tests as indicated
treatment for fever in a returning traveller
isolation (? PPE)
supportive measures (resuscitation)
empirical treatment if patient unwell (antimicrobial therapy based on likely diagnosis, aim to treat life threatening conditions e.g typhoid, septicaemia)
specific treatment once diagnosis established
