Travel Related Infection Flashcards
Why are travelers more vulnerable to infection?
They take risks they might not normally take (sex, water, food and animals)
They are in countries with different epidemiologies of disease (HIV, TB, polio and diptheria)
Incomplete understanding of health hazards
If the traveller is a refugee they may be deprived, malnourished, diseased or even injured.
What are some infections that are common worldwide?
Influenza
Community acquired pneumonia
Meningococcal disease
Sexually transmitted disease
What are some examples of climate or environmental related health problems?
- Sunburn
- Heat exhaustion and heatstroke
- Fungal infections
- Bacterial skin infections
- Cold injury
- Altitude sickness
Give examples of some ifnections controlled by public health measures
Sanitation:
- Travellers diarrhoea
- Typhoid
- Cholera
- Viral gastroenteritis
Immunization:
- Poliomyelitis
- Diptheria
Education:
- HIV
- STD’s
What are some water related infections?
- Schistosomiasis
- Leptospirosis
- Liver flukes
- Strongyloidiasis
- Hookworms
- Guinea worms
Give examples of arthropod - borne infections
Malaria (mosquitos)
Dengue fever (mosquitos)
Leishmaniasis (sand flies: kala-azar)
Filariasis (mosquitos: elephantiasis)
What are some emerging infections?
Zika - latin america, caribbean
Ebola virus - west africa
Avian flu - china
West Nile virus - USA
What is the main vector of malaria?
Female anopheles mosquito
What species is the potentially severe form of malaria?
Plasmodium falciparum
Bengn includes:
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
What are the clinical features of malaria?
Symptoms:
- •fever
- rigors
- aching bones
- abdo pain
- headache
- dysuria
- frequency
- sore throat
- cough
What are the signs of malaria?
None
Splenomegaly
Hepatomegaly
Mild-jaundice
What are the complications of malaria?
Cerebral malaria (encephalpathy) - coma
Blackwater fever - server intravascular haemolysis (high parasitaemia, profound anaemia, haemaglobulinuria, acute renal failure)
Pulmonary oedema
Jaundice
Severe anaemia
Algid malaria (gram negatice septicaemia)
How is the diagnosis of malaria made?
•Thick & thin blood films
–Giemsa, Field’s stain
•Quantitative buffy coat (QBC)
–centrifugation, UV microscopy
•Rapid antigen tests
–OptiMal
–ParaSight-F
On blood films you can see the parasite within the red blood cells
What defines malaria as being complicated malaria?
- Impaired consciousness or seizures
- Hypoglycaemia
- Parasite count greater than or equal to 2%
- Haemoglobin less than or equal to 8mg/dL
- Spontaneous bleeding / DIC
- Haemoglobinuria
- Renal impairment or pH <7.3
- Pulmonary oedema or ARDS
- Shock (algid malaria)
–?Gram negative bacteraemia
What are the treatment options for uncomplicated plasmodium falciparum?
Riamet - 3 days
Eurartesim - 3 days
Malarone - 3 days
Quinine (plus oral doxycycline or clindamycin) - 7 days
What are the treatment options for complicated or severe plasmodium falciparum malaria?
IV artesunate (unlicensed in the UK)
IV quinine (plus oral doxycycline or clindamycin)
What is treatment of P. vivax, p.ovale. p. malariae, p.knowlesi?
Chloroquine for 3 days
Riamet - 3 days
Add primaquine (14 days) in vivax and ovale tp eradicate liver hypnozoites
Before using primaquine you need to check for G6PD deficiency
What are malaria control programmes?
•Mosquito breeding sites
–Drainage of standing water
•Larvacides
–(Paris green), temphos, biological
•Mosquito killing sprays
–DDT, malathion, (dieldrin)
•Human behaviour
–Bed nets
–Mesh windows
What are the causative organisms for typhoid?
Salmonella typhi
Salmonella paratyphi
What are the clinical features of typhoid?
•Incubation period: 7 days - 4 week
•1st week:
fever, headache, abdo. discomfort, constipation, dry cough, relative bradycardia, neutrophilia, confusion
•2nd week:
fever peaks at 7-10 days, Rose spots, diarrhoea begins, tachycardia, neutropenia
•3rd week (Complications):
intestinal bleeding, perforation, peritonism, metastatic infections
•week 4 (Recovery):
10 - 15% relapse
How is the diagnosis of typhoid fever made?
•Clinical
–not easy
–evolution of features
•Laboratory (Salmonella typhi, S. paratyphi)
–Culture blood, urine & stool
–Culture bone marrow
What is the treatment for typhoid fever?
Oral azithromycin
IV ceftriaxone - if complicated or concerned regarding absorption
What is the commonest human arbovirus infection?
Dengue
What causes the transmission of dengue?
Aedes aegypti
What is the classical presentation of dengue fever?
- Sudden fever
- Severe headache, retro-orbital pain
- Severe myalgia and arthralgia
- Macular/ maculopapular rash
- Haemorrhagic signs: petechiae, purpura, positive tourniquet test
What is the tourniquet test? What does it assess?
It assesses a patients haemorrhagic tendancy and capillary fragility. It is part of the WHO algorith for diagnosis of dengue fever.
A blood pressure cuff is applied and inflated to the midpoint between the systolic and diastolic blood pressures for five minutes. The test is positive if there are more than 10 to 20 petechiae per square inch
What is the clinical and laboratory diagnosis of dengue?
Clinical:
–Thrombocytopenia
–Leucopenia
–Elevated transaminases
–Positive tourniquet test
Laboratory - PCR, serology
What are the therapeutic agents for dengue fever?
No specific therapeutic agents
What are the complications for dengue?
–Dengue haemorrhagic fever (DHF)
–Dengue shock syndrome (DSS)
Rx: IV fluids, fresh frozen plasma, platelets
What are the prevention methods for dengue?
Avoid bites
New vaccine (dengvaxia), 2016 limited use
What are the transmitting organisms for schistosomiasis?
Freshwater snails
What are the micro-organisms assocaited with schistosomiasis?
- S. haematobium
- S. mansoni
- S. japonicum
What is the schistosomiasis life cycle?
Eggs hatch releasing miracidia
Miracidia penetrate snail tissue
Sporocysts form in snail tissue
Sporocysts form cercariae which can penetrate human skin
Circariae shed their forked tail forming schistosomulae
Schistosomulae reside in the veins of the human host
Eggs are eliminated in faeces of urine
What are the clinical features of schistosomiasis?
•Swimmers Itch (1st few hrs)
–clears 24-48hrs
•Invasive stage (after 24hrs)
–cough, abdo discomfort, splenomegaly, eosinophilia
•Katayama Fever (after 15-20 days)
–prostrate, fever, urticaria, lymphadenopathy, splenomegaly, diarrhoea, eosinophilia
•Acute disease (6-8 weeks)
–eggs deposited in bowel (dysentery) or bladder (haematuria)
•Chronic disease
What is the diagnosis of schistosomiasis?
–Clinical diagnosis
–Antibody tests
–Ova in stools and urine
- Rectal snip
What is the treatment for schistosomiasis?
–PRAZIQUANTEL 20mg/kg, 2 doses 6hrs apart
–Prednisolone if severe
What diseases is caused by tick typhus, give an example of the causative organism
Rickettsiosis
R. Conorii
What are the clinical features of rickettsiosis?
Abrupt onset, swinging fever, headache, confusion, endovasculitis, rash (macular, petechial), bleeding
What is the diagnosis of rickettsiosis?
Clinical features
Serology
What is the management of rickettsiosis?
Tetracycline
Give examples of viral haemorrhagic fevers
Ebola
CCHV - crimean congo haemorrhagic fever
Lassa fever
Marburg disease
What is the primary prevention method for spread of viral haemorrhagic fevers?
High security infection unit
Treatment is supportive
What virus causes Zika?
Flavivirus
What transmits the zika virus?
Daytime - biting aedes mosquitos
Also by sexual contact, blood transfusion
•Related to dengue, yellow fever, Jap B encephalitis and West Nile viruses
What geographical areas were associated with outbreaks of zika virus?
Pacific outbreak - 2013-2014
Latin america pandemic 2015 - 2016
What are the clinical features of zika virus?
•Clinical: no or mild symptoms - headache, rash, fever, malaise, conjunctivitis, joint pains (like dengue)
In pregnancy can cause microcephaly and other neurological symptoms
Can cause guillain-barre syndrome
What are the control measures for Zika?
- No antiviral therapy
- Mosquito control measures
- Vaccines in development
What is the most likely causes of fever in the patient returning from travel?
Malaria
What travel disease might a rash be a sign of?
typhoid, typhus, dengue
What might jaundice be a sign of?
Hepatitis
Malaria
Yellow fever
What might lymphadenopathy be a sign of?
leishmania, trypanosomiasis
What might enlarged liver be a sign of?
malaria, typhoid, amoebic abscess
What might splenomegaly be a sign of?
•visceral leishmaniasis, typhoid, malaria
Investigations
- FBC
- malaria films
- liver function tests
- stool microscopy & culture
- urine analysis & culture
- blood culture(s)
- CXR
Specific tests as indicated
–dengue
–respiratory viral/atypical
–hepatitis A, B, C
–tick typhus (Rickettsia)
–schistosomiasis
–amoebic
–leptospirosis/hantavirus
–viral haemorrhagic fevers
Treatment
- Isolation: ?personal protective equipment
- 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 is established
