Travel related infection Flashcards
What are the unfamiliar features of imported diseases?
○ Presenting features ○ Isolation requirements ○ Diagnostic methods ○ Treatment/ Management ○ Unexpected complications
Why are travelers valnerable 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
Give examples of water related infections
○ Schistosomiasis ○ Leptospirosis ○ Liver flukes ○ Strongyloidiasis ○ Hookworms ○ Guinea worms
Give examples of arthropod-borne infections
○ Malaria (mosquitos)
○ Dengue fever (mosquitos)
○ Rickettsial infections (ticks: typhus)
○ Leishmaniasis (sand flies: Kala-azar)
○ Trypanosomiasis (tsetse fly: sleeping sickness)
○ Filariasis (mosquitoes: elephantiasis)
○ Onchocerciasis (black flies: River Blindness)
What is the epidemiology
of malaria?
- Most important imported disease
- United Kingdom (HPA, 2015)
□ 1400 cases/year
□ 6 deaths/year - Worldwide (WHO, 2012)
□ 207 million cases/year
□ 627,000 deaths/year
What are the symptoms of malaria?
□ fever □ rigors □ aching bones □ abdominal 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 (encephalopathy) □ non- immune visitors, children in endemic areas □ hypoglycaemia, convulsions, hypoxia - Blackwater fever □ severe intravascular haemolysis, high parasitaemia, profound anaemia, haemoglobinuria, acute renal failure - Pulmonary oedema - Jaundice - Severe anaemia - Algid malaria □ Gram-negative septicaemia
How is malaria diagnosed?
- Thick & thin blood films □ Giemsa, Field’s stain - Quantitative buffy coat (QBC) □ centrifugation, UV microscopy - Rapid antigen tests □ OptiMal □ ParaSight-F
How is the severity of malaria assessed?
- Complicated malaria= one or more of □ Impaired consciousness or seizures □ Hypoglycaemia □ Parasite count ≥2% □ Haemoglobin ≤ 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 falciparum malaria?
- Riamet ® (artemether-lumefantrine) 3 days
- Eurartesim ® (dihydroartemisinin-piperaquine) 3 days
- Malarone ® (atovaquone-proguanil) 3 days
- Quinine 7 days
□ S/E nausea, tinnitus, deafness (cinchonism), rash, hypoglycaemia
□ plus oral doxycycline (or clindamycin)
What is the treatment for complicated or severe P. falciparum
- IV artesunate (unlicensed in UK)
- IV quinine
□ (S/E cardiac depression, cerebral irritation, N&V)
□ plus oral doxycycline (or clindamycin) - When patient is stable & able to swallow, switch to oral treatments
What is the treatment of P. vivax, P. ovale, P. malariae and P. knowlesi?
- chloroquine 3 days
- Riamet ® (artemether-lumefantrine) 3 days
□ add primaquine* (14 days) in vivax and ovale, to eradicate liver hypnozoites (*check for G6PD deficiency)
Give examples of malaria control programs
- 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 organisms cause typhoid?
- Salmonella typhi
- Salmonella paratyphi
What is the epidemiology of typhoid
- Global cases: 27 million infections/year
- Global deaths: over 200,000/year
- UK cases: 500/year
- Widespread
□ poor sanitation, unclean drinking water
What are the clinical features of typhoid?
- Incubation period: 7 days - 4 week
□ 1st week:
® fever, headache, abdominal 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 typhoid diagnosed?
- Clinical □ not easy □ evolution of features - Laboratory (Salmonella typhi, S. paratyphi) □ Culture blood, urine & stool □ Culture bone marrow
What is the treatment for typhoid?
- Oral Azithromycin
□ now drug of choice for Asian-acquired, uncomplicated enteric fever - IV Ceftriaxone
□ if complicated, or concerned regarding absorption - Increasing ciprofloxacin resistance
What is the epidemiology of dengue?
- Swahili: “Ki-Dinga pepo”
- Commonest human arbovirus infection
- Dengue infection: 100 million cases/year
- Dengue Deaths: 25,000/year
How is dengue transmitted?
- Aedes aegypti
- Breeds in stagnant water
- Very difficult to get rid of the breeding site
What is classic dengue fever?
- Sudden fever
- Severe headache, retro-orbital pain
- Severe myalgia and arthralgia
- Macular/ maculopapular rash
- Haemorrhagic signs: petechiae, purpura, positive tourniquet test
How is dengue diagnosed?
- Clinical □ Thrombocytopenia □ Leukopenia □ Elevated transaminases □ Positive tourniquet test - Laboratory: PCR, serology
How is dengue managed?
- No specific therapeutic agents
- Complications
□ Dengue haemorrhagic fever (DHF)
□ Dengue shock syndrome (DSS)
□ Rx: IV fluids, fresh frozen plasma, platelets - Prevention
□ avoid bites
□ new vaccine (Dengvaxia), 2016; limited use
What organism causes schistosomiasis?
Freshwater snails
What are the clinical features of schistosomiasis?
- Swimmers Itch (1st few hrs)
□ clears 24-48hrs - Invasive stage (after 24hrs)
□ cough, abdominal 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
□ Occurs in the developing world and results in neurological deficiencies
How is schistosomiasis diagnosed?
- Clinical diagnosis
- Antibody tests
- Ova in stools and urine
- Rectal snip
How is schistosomiasis treated?
- PRAZIQUANTEL 20mg/kg, 2 doses 6hrs apart
- Prednisolone if severe
What is tick typhus?
A spotted fever condition spread by ticks
What organisms can cause tick typhus?
- Rocky Mountain Spotted Fever (R. rickettsii)
- Epidemic typhus (R. prowazekii)
- Murine or endemic typhus (R. mooseri)
- Scrub typhus (R. tsutsugamushi)
- others
What are the clinical features of tick typhus?
- abrupt onset swinging fever
- Headache
- Confusion
- Endovasculitis
- rash (macular, petechial)
- Bleeding
How is tick typhus diagnosed?
- Clinical features
- Serology
What is the management of tick typhus?
Tetracycline
Give examples of viral haemorrhagic fevers?
- Ebola
- Congo-Crimea haemorrhagic fever
- Lassa fever
- Marburg disease
What should be done in the case of viral haemorrhagic fevers?
○ Maximum incubation period 3 weeks
○ Rule out common severe infections
○ Isolation: High Security Infection Unit
○ Treatment: supportive!
What organisms cause zika?
- flavivirus
- Transmitted by daytime-biting Aedes mosquitos
- Also by sexual contact, blood transfusion
What are the clinical features of zika?
○ No or mild symptoms - headache, rash, fever, malaise, conjunctivitis, joint pains (like dengue)
○ In pregnancy, can cause microcephaly and other neurological problems
○ Can cause Guillain-Barre syndrome
What is the management of zika?
- No antiviral therapy
- Mosquito control measures
- Vaccines in development
What should be asked in the history of a returning traveler with a fever?
- Is it tropical?
- Travel history
- Precautions taken
- Risks
- Symptoms
- Incubation periods
What examinations should be done with a returning traveler with a fever?
- rash - typhoid, typhus, dengue
- jaundice - hepatitis, malaria, Yellow fever
- lymph nodes - leishmania, trypanosomiasis
- liver - malaria, typhoid, amoebic abscess
- spleen – visceral leishmaniasis, typhoid, malaria
What investigations should be done in a returning traveler with a fever?
- FBC
- malaria films
- liver function tests
- stool microscopy & culture
- urine analysis & culture
- blood culture(s)
- CXR
- Specific tests (as indicated)
What treatment should be given to a returning traveler with a fever?
- 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
