Y4 - Infection in the Returning Traveller Flashcards
If a patient turns up to their GP with a fever after being abroad what MUST you do before referring them to hospital?
Do a risk assessment for viral haemorrhagic fevers
Why is it important to know the dates of travel?
As they link to the incubation periods of the pathogens
Give examples of viral haemorrhagic fevers
Ebola Lassa fever Crimean-Congo HF Dengue Yellow fever
What are haemorrhagic fevers?
Severe, multi-organ disease in which the endothelium is damaged and homeostasis is impaired
What kind of virus is dengue?
Flavivirus
How is dengue transmitted?
Aedes mosquito bite
When do the Aedes mosquitoes bite?
Day time
What is the incubation period of dengue?
3-14d
What is the presentation of dengue?
Fever, NV, headache, retroorbital pain, arthralgia
How do you investigate dengue?
PCR for virus or serology after 5d
What drug should you avoid using in someone with dengue?
NSAIDs
What is the treatment of dengue?
Supportive (fluids, analgesia etc.)
Name 4 diseases spread by mosquitos
Dengue
Malaria
Elephantiasis
Yellow fever
True or false: malaria treatment should be started empirically
FALSE
Only on diagnosis, hence why if malaria is suspected then malarial blood film must be done on call
In who should you always think about a diagnosis of viral haemorrhagic fever?
Any traveller with fever presenting within 21d of return to the UK
What sort of things would indicate a high risk of a VHF?
Fever/hx of fever in past 24h
Developed symptoms w/I 21d of leaving VHF endemic country
Come into contact with body fluids/clinical specimens from individual strongly suspected to have VHF w/I last 21 days
If you really suspect VHF what should you do?
ISOLATE patient
Urgent malaria investigation
FBC, U&Es, LFTs, clotting screen, CRP, glucose, blood cultures
Inform lab of possible VHF case
Hand hygiene, double glove, full length apron etc.
If there is a low risk of VHF in patient returning with fever after travel what should you do?
Urgent malaria investigation
Local investigations, e.g. blood cultures
Standard IPC (hand hygiene, apron, gloves)
If a patient returns from travel, presenting with a fever within 21d and malaria test is negative, what is the treatment protocol?
If patient has extensive bruising, active bleeding, uncontrolled diarrhoea/vomiting or is unfit for outpatient management –> ADMIT
VHF test positive –> launch public health actions, need high level isolation unit
What are the reservoirs for Ebola?
Fruit bats
What is the pathogenesis of Ebola?
Cytokine activation leads to endothelial damage, oedema, coagulopathy and tissue necrosis leading to multi-organ failure
How is Ebola spread?
Direct contact with mucous membranes/bodily fluids, burial contact
What is the presentation of Ebola?
0-3d: fever, myalgia, weakness, anorexia, headache, sore throat
4-10d: ab pain, liver tenderness, NV, hiccups, diarrhoea, hypovolaemia
>10d: haemorrhagic: petechiae, ecchymosis, mucosal haemorrhage, GI bleeding, haemoptysis; neurological: weakness, confusion, agitation, coma and others
May get post infection conditions, e.g. arthralgia, hepatitis, orchitis, transverse myelitis etc.
How do you diagnose Ebola?
Serology
Reverse transcriptase PCR on blood/urine/saliva/throat swab
How do you treat Ebola?
Supportive (fluid resus, correct electrolytes/coagulation etc.)
Trace contacts
What is the risk assessment for VHF in the UK?
Transmission: 1. travel to endemic area or lived/worked in rural conditions (Lassa fever) or visited caves/mines or been in contact with/eaten primates/antelopes or bats in Marburg/Ebola endemic areas or been involved with animal slaughter (CCHF) 2. travel to known outbreak 3. contact with infected specimen
Fever >37.5C in last 24h
What are the species that cause malaria?
Plasmodium species P. falciparum P. knowlesi P. malariae P. ovale P. vivax
What type of mosquitos carry malaria?
Females anopheles
Only females require a bloodmeal for egg development
Transmission in absence of a mosquito is rare (e.g. vertical, transfusion etc.)
Fill in the blanks:
_________ are transferred to a human host when an infected mosquito bites. These travel via the blood to the _______ where maturation occurs to form _______ which contain around 30, 000 __________ offspring. If a dormant stage exists (vivax, ovale) ______ can be released from the ______ years later. ________ enter RBCs, there they form ________ and erythrocytic ______. Rupture of these leads to the clinical manifestations of malaria.
Sporozytes Liver schizonts Merozoites Merozoites Liver Merozoites Larger trophozoites Schizonts
How long does it take most people infected with P. falciparum to have symptoms?
Less than 3 months
What are the symptoms of malaria?
Fever, headache, malaise, myalgia, diarrhoea, cough
May have fever patterns
What are the signs of malaria?
May be none
If diagnosis delayed/severe disease may present with jaundice, confusion, seizures
How do you diagnose malaria?
Thick and thin blood smear
Rapid diagnostic test detection of parasite antigen may be used in addition but not instead of blood smear
Results must be available within 4 hours
Parasite count must be given for P. falciparum
What are differentials for malaria?
Dengue Typhoid Hepatitis Meningitis/encephalitis HIV VHF
What other investigations should you do for malaria?
FBC (anaemia, thrombocytopenia), creatinine, urine output, clotting (DIC), glucose (hypoglycaemia), ABG/lactate (acidosis), urinalysis (haemogobulinuria)
Blood culture for typhoid
CXR to exclude community acquired pneumonia
How do you manage complicated falciparum malaria?
Admit to hospital (may need ITU/HDI)
Supportive care: oxygen, fluids, ECG monitoring and blood glucose monitoring (esp during IV quinine)
4hrly obs
Repeat FBC, clotting, U&Es, LFTs and parasite count daily
Antimalarials:
- Artesunate IV 2.4mg/kg at 0, 12, 24hrs for 7 days + doxycycline or clindamycin
How long is the incubation period of malaria?
At least 6 days
What is complicated malaria?
1 or more of:
- impaired consciousness/seizures (CHECK blood glucose straight away)
- Hypoglycaemia
- Parasite count 2% or more
- Hb 8d/dL or less
- Spontaneous bleeding/DIC
- Haemoglobulinuria without G6PD deficiency
- Renal impairment/electrolyte/acid base disturbance (pH <7.3)
- Pulmonary oedema/ARDS
- Shock (algrid malaria) may be due to gram negative bacteraemia
How do you treat uncomplicated falciparum malaria?
a) oral quinine 600mg/8h plus doxycycline 200mg daily (or clindamycin 450mg/8h) for 7 days
b) malarone - 4 tablets daily for 3 days
c) Riamet - wt >35kg, 4 tablets and then 4 tablets at 8, 24, 36, 48 and 60h
How do you treat non-falciparum disease?
If severe Rx as falciparum
If not severe - chloroquine
How do you prevent malaria?
Vector control (e.g. insecticidal nets, sterile male mosquito release, destruction of breeding sites etc.)
Chemoprophylaxis
- no drug resistance: chloroquine/proguanil
- little chloroquine resistance: chloroquine and proguanil
- chloroquine resistant P. falciparum: mefloquine, doxycycline
Bite prevention - DEET
Where does typhoid tend to affect travels?
India, Pakistan etc.
What causes typhoid?
Salmonella typhi
Where do salmonella typhi invade?
Intestinal mucosa
But dissemination occurs without a primary diarrhoea
What is the transmission of typhoid?
Faecal-oral from contaminated food/water
How do you diagnose typhoid?
Culture from blood sample
What are the clinical features of typhoid?
Fatigue, headache, anorexia, fever
May also get diarrhoea, ab pain, hepatosplenomegaly, rose spots, cough, constipation
How do you treat typhoid?
Azithromycin & IV ceftriaxone
What causes typhus?
Infection with rickettsial bacteria
Flea born typhus in tropical areas or louse-borne typhus in homeless populations
How do you diagnose typhus?
Clinical: fever, rash, travel to endemic area
PCR/culture of blood/skin biopsy
Serology
How do you Rx typhus?
Antibiotics in severe cases (e.g. azithromycin, doxycycline)
What is schistosomiasis?
Liver fluke
What can schistosomiasis cause if left untreated?
Chronic scarring causing uropathy or portal hypertension
How do you Rx schistosomiasis?
Praziquantel
What is strongyloides?
A helminth that can cause a hyperinfection syndrome if someone becomes immunosuppressed
(Marked eosinophilia)
