Session 5 - Travel infections Flashcards
Give four reasons why travel history is important?
• Imported diseases are rare/unknown in UK
• Different strains of pathogen may be present, adding to difficulty of treatment
- Antibiotic resistance
Why does having different strains of pathogen make treatment difficult?
• Antigenically different, which impacts on protection and detection
What are six key aspects of travel history
- Where?
- When?
- How (direct or via)?
- Accommodation
- How long?
- Specific risks (including sexual contact
- Preventative measures
Outline a differential diagnosis with 6 different possibilities after someone has returned from central Africa
- Malaria
- Typhoid
- Meningococcal septicaemia
- Dengue
- Yellow fever
Non-travel related infection
What are the four main species of malaria?
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
What is the malaria vector?
• Anopheles mosquito
How many cases of malaria each year? How many deaths?
- 250 million
* 1 million
What is the incubation period of malaria?
• 1-3 weeks after bite
Give the symptoms of malaria
- Headache
- Cough
- Fatigue
- Malaise
- Arthralgia
- Myalgia
- Fever and chills which eventually cycle every three/four days
Give three additional features you may see upon examination of someone with
- Splenomegaly
- Cerebral features - Coma
- Respiratory distress (metabolic acidosis, pulmonary oedema)
Give five tests you would perform on someone you suspected of harboring the malaria parasite
- Blood smear to detect parasiste
- Full blood count
- Urea and electrolytes
- Liver function test
- Glucose
- Head CT if coma
What treatment would you give for a malignant “P. Falciparum’ infection?
- Quinine
* Artemisinin
What treatment would you give for benign P. Vivax, ovale or malariae?
• Chloroquine
+/- primaquine (for exo-erythrocytic phase)
What are the three main stages of life cycle of plasmodium?
- Exo-erythrocytic
- Erythrocytic
- Mosquito stages
What occurs in the mosquito stage?
• Mosquite takes a blood meal from infected host, ingesting gametocytes
Plasmodium develops in mosquito
What occurs in the exo-erythrocytic cycle?
- Plasmodium infects hepatocyte and forms schizont
* Shizont ruptures, spreading malaria into blood
What occurs in the erythrocytic stage?
Schizonts form and rupture
What are the ABC’s of malaria prevention?
• Assess risk - Knowledge of at risk areas ○ Regular/returning travellers • Bite prevention ○ Repellant, adequate clothing, nets ○ Chemoprophylaxis before travel • Chemoprophylaxis ○ Specific to region ○ Start before and continue after return
How many cases of typhoid and paratyphoid fever are there per year in the UK?
• 500/year
What is the mechanism of infection of typhoid and paratyphoid infection?
Faecal-oral from contaminated food/water, source is cases or carriers
What organism causes typhoid and paratyphoid?
• Salmonella enterica serovar
Categorise salmonella enterica serovar
• Enterobacteriaceae, aerobic gram-negative rod
Non-lactose fermenter
How virulent is salmnella enterica serovar?
- Secretes gram negative
- Substance called invasin allows intracellular growth
- Fibrimae adhere to epithelium over ileal lymphoid tissue (peyer’s patches) -> RE system
What is enteric (typhoid) fever?
• Systemic disease with fever and headache
