Week 3 - infection and immunity Flashcards
Describe the presentation of fevers. (LO1)
- Rigors.
- Night sweats.
- Excessive sweating.
- Recurrent fever.
Accompanying features:
- Severe headache and photophobia.
- Delirium.
- Myalgia.
- Shock may accompany severe infections and sepsis.
Describe the history-taking aspect of investigations of fevers. (LO1)
- Presenting complaint.
- System review.
- Past medical history.
- Medication history.
- Allergy history.
- Family history.
- Contact history.
- Travel history.
- Occupation.
- Recreational pursuits.
- Animal exposures.
- Dietary history.
- Sexual history.
Describe the clinical investigations of fevers. (LO1)
- Full blood count (FBC).
- Urea and electrolytes (U+Es).
- Liver function tests (LFTs).
- Blood glucose.
- Muscle enzymes.
- Inflammatory markers: ESR, CRP.
- Test for HIV-1 antibodies.
- Autoantibodies, including antinuclear antibodies (ANA).
- Urinalysis and urine culture.
- Blood culture.
- Throat swab for culture or PCR.
- Other speciments as indicated by history - wound swab, sputum culture, stool culture, microscopy, C. diff toxin assay.
- Specific tests and their priority.
What disease specific tests would be done provided the history indicated it (fever)? (LO1)
- Malaria films on 3 consecutive days or malaria rapid diagnostic test (antigen detection).
- Test for non-structural protein (NS1) in dengue (antigen detection).
- Blood cultures for Salmonella typhi.
- Abdominal ultrasound standard test in many regions of Africa, Asia, Oceania and Central and South America.
Describe the features of factitious fever. (LO1)
- Patient who looks well.
- Bizarre temperature chart with absence of diurnal variation or temperature-related changes in pulse rate.
- Temperature >41°C.
- Absence of sweating during defervescence.
- Normal erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), despite high fever.
- Evidence of self-injection or self-harm.
- Normal temperature during supervised (observed) measurement.
- Infection with multiple commensal organisms (e.g. enteric or mouth flora).
Describe the initial management of fever. (LO1)
- Fever and associated symptoms can be treated with paracetamol.
- Tepid sponging to cool the skin.
- Replenishing of salt and water is important in patients with drenching sweats.
- Further management is focused on underlying cause.
Why is past medical history important when asking about a presenting complaint of fevers? (LO1)
- Defines the ‘host’ and likelihood of infection.
- Includes surgical and dental procedures involving prosthetic materials.
- Document previous infections.
- History of intravenous drug injection or receipt of blood products.
- Risks for blood-borne viruses, e.g. HIV-1, HBV, and HCV.
Why is medication history important when asking about a presenting complaint of fevers? (LO1)
- Include non-prescription drugs, use of antimicrobials and immunosuppressants.
- Identify medicines that interact with antimicrobials or that may cause fever.
Why is allergy history important when asking about a presenting complaint of fevers? (LO1)
- Could have an allergy to anti-microbials, noting allergic manifestations (e.g. rash vs. anaphylaxis).
Why is family and contact history important when asking about a presenting complaint of fevers? (LO1)
- Checking for transmissible diseases such as TB, HIV, etc.
Why is travel history important when asking about a presenting complaint of fevers? (LO1)
- Countries visited and whether they were a previous resident.
- Gives info about relevant exposure and likely vaccination history, e.g. likelihood of BCG vaccination in childhood.
Why is occupation important when asking about a presenting complaint of fevers? (LO1)
- Occupational hazard.
- e.g. Anthrax in leather tannery workers.
- Ask about occupation-related vaccines.
Why is recreational pursuit important when asking about a presenting complaint of fevers? (LO1)
- Could be caused by the activity.
- e.g. Leptospirosis in canoeists and windsurfers.
Why is animal exposure important when asking about a presenting complaint of fevers? (LO1)
- Including pets, e.g. dogs.
- Could be hydatid disease.
Why is dietary history important when asking about a presenting complaint of fevers? (LO1)
- Undercooked meats, shellfish, unpasteurised dairy products or well water.
- Establish who else was exposed, e.g. to food-borne pathogens.
- Risks for blood-borne viruses, e.g. HIV-1, HBV, and HCV.
Why is sexual history important when asking about a presenting complaint of fevers? (LO1)
- Explore in confidential manner.
- Most common mode of HIV-1 transmission is heterosexual.
- Vaccine history and use of prophylactic drugs.
- In a traveller or infection-predisposed patient, establish adherence to prophylaxis.
List the common differential diagnoses for bacterial infections causing fever. (LO1)
- Osteomyelitis.
- Pyelonephritis.
- Abscess.
- Infective endocarditis.
- Tuberculosis.
- Cat scratch disease.
- Typhoid fever.
List the common differential diagnoses for viral infections causing fever. (LO1)
- Epstein-Barr virus.
- Cytomegalovirus.
- Enterovirus.
- Adenovirus.
List the common differential diagnoses for malignancies causing fever. (LO1)
- Leukaemia.
- Lymphoma.
- Neuroblastoma.
List the common differential diagnoses for autoimmune diseases causing fever. (LO1)
- Juveline idiopathic arthritis (JIA).
- Systemic lupus erythamatous (SLE).
- Inflammatory bowel disease (IBD).
List the common differential diagnoses for miscellaneous causes of fever. (LO1)
- Kawasaki disease.
- Drug fever.
- Periodic fever.
Describe the epidemiology of sepsis. (LO2)
- In 2017, 48.9 million cases and 11 million sepsis-related deaths worldwide, accounting for 20% of all global deaths.
- 80% of sepsis cases and sepsis-related deaths worldwide occured in low, middle income countries.
- In 2017, almost half of all global sepsis cases occured among children, 20 million cases and 2.9 million deaths in children <5 years.
- Increased incidence can be due to: immunosuppression therapy, invasive procedures, transplantation, chemotherapy, newborns, old age, pregnancy, chronic health conditions.
Define sepsis. (LO2)
The body’s amplified and dysregulated inflammatory response to infection (involving cytokine storm, e.g. tumour necrosis factor and IL-1). This leads to an imbalance between proinflammatory and anti-inflammatory responses. Also known as, systemic inflammatory response syndrome.
Define septicaemia. (LO2)
Bacterial infection in the blood.