Infections and Immunology Flashcards
Define Behcet’s disease
An autoimmune systemic vasculitis affecting all sized vessels, leading to recurrent oral and genital ulcers and uveitis. It can cause skin and mucosal lesions, uveitis, major arterial and venous vessel disease, and GI and neurological manifestations.
Summarise the aetiology of Behcet’s disease
Underlying aetiology is unknown
Autoimmune or autoinflammatory
Associated with HLA-B51
Innate and active immune system involved
Risk factors:
Age 20-40 years
Family history of Behcet’s syndrome
Genetic predisposition.
Summarise the epidemiology of Behcet’s disease
Most common in those 20-40 years old
More severe symptoms in men
Most common in Turkey, Mediterranean, Israel, East Asia
What are the presenting symptoms and signs on physical examination of Behcet’s disease?
Recurrent oral and genital ulcers which are painful, slow healing and large Anterior uveitis - painful, red eye with decreased vision and sterile pus Posterior uveitis - painless eye with decreased vision and floaters Skin lesions - erythema nodosum Joint stiffness Abdominal pain Meningitis - headache, confusion, fever Arthritis Thrombophlebitis Vasculitis Myocarditis/pericarditis CNS symptoms Colitis
What are appropriate investigations for Behcet’s disease?
Mostly a clinical diagnosis
Pathergy test - pin prick does not heal normally, becomes inflamed and forms ulcer or lesion (sterile pustule) at that site within 48 hours
Rheumatoid factor to rule out RA (negative)
Define malaria
A parasitic infection caused by plasmodium species which is transmitted to humans through a bite from an infected female anopheles mosquito.
Summarise the aetiology of malaria
There are 5 types of protozoa which can cause malaria in humans: Plasmodium falciparum Plasmodium malariae Plasmodium vivax Plasmodium ovale Plasmodium knowlesi
P. falciparum causes malaria most often and most severe malaria
Malaria is spread by the bite of an infected female Anopheles mosquito
Sickle cell disease, thalassemia and 6PD deficiency are protective against malaria
Summarise the epidemiology of malaria
Endemic in the tropics
In endemic countries it is most common in children <5 years old and pregnant women
What are the presenting symptoms of malaria?
Feverish traveller Cyclic fevers Headaches Myalgia Arthralgia Fatigue Rigors Weakness Anorexia Flu-like symptoms Sweating Vomiting
Cerebral Malaria Symptoms: headache, disorientation, coma, confusion
What are the signs on physical examination of malaria?
Pyrexia Anaemia (haemolytic) Hepatosplenomegaly Tachycardia Jaundice
What are the appropriate investigations for malaria?
FBC - normocytic anaemia, thrombocytopenia
Giemsa-stained thick blood smear - identify the presence of parasite within RBC
Thin blood smear - identify the specific plasmodium
Rapid diagnostic tests
Serum LFTs: may show elevated BR/aminotransferases
Clotting profile - may have prolonged prothrombin time
Define Sjogren’s syndrome
Autoimmune destruction and lymphocytic infiltration of exocrine glands, particularly the lacrimal and salivary glands, resulting in dry eye and dry mouth.
Summarise the aetiology of Sjogren’s syndrome
Primary Sjogren’s syndrome - sicca syndrome when it occurs on its own
Secondary Sjogren’s syndrome - Sjogren’s occuring with another autoimmune disorder
Aetiology unknown
Associated with HLA-B8 and HLA-DR3
Associated with infection of exocrine glands
Can be associated with: Rheumatoid arthritis SLE Scleroderma Polymyositis Organ-specific autoimmune diseases (e.g. PBC, autoimmune hepatitis, myasthenia gravis)
Summarise the epidemiology of Sjogren’s syndrome
The most common of all systemic auto-immune rheumatic diseases
More common in women
Middle aged women - 50-60 years old
60% have the disease secondary to rheumatoid arthritis, SLE, or systemic sclerosis
What are the presenting signs and symptoms of Sjogren’s syndrome?
Keratoconjunctivitis: Blurred vision Red eye Itchy eye Dry eye Burning eye
Xerosterma:
Dry mouth
Difficulty tasting and swallow
Cracks and fissures in mouth
Crusting and bleeding of nasal septum Dry skin Dry vagina - causes dyspareuria Pain Lymphadenopathy Fever Weight loss Fatigue Dry upper airways: leads to a dry cough and recurrent sinusitis Dry skin or hair Dry upper airways: leads to a dry cough and recurrent sinusitis - Dry skin or hai Dental caries Myalgia
What are the appropriate investigations for Sjogren’s syndrome?
ESR - elevated Amylase - elevated if salivary gland involvement Anti-SSA and anti-SSB - positive Rheumatoid factor positive ANA
Schirmer’s Test:
A strip of filter paper is placed under the eyelid
Positive for Sjogren’s syndrome if < 10 mm of the strip is wet after 5 mins
Fluorescein/Rose Bengal Stains: May show punctate or filamentary keratitis
Reduced parotid salivary flow rate
Reduced uptake or clearance on isotope scan
Biopsy salivary or labial glands - shows lymphocytic infiltration
Sialometry - decreased saliva outflow
Define systemic lupus erythematosus
A chronic multi-system autoimmune condition which mainly affects women of reproductive age and is characterised by the presence of anti-nuclear antibodies.
4 out of the 11 features must be present for diagnosis:
RASH OR PAIN
Rash - malar or discoid
Arhritis
Serositis - pleuritis, pericarditis
Haemological disorders - haemolytic anaemia, thrombocytopenia, leukopenia
Oral/nasopharyngeal ulcers
Renal disease - proteinuria, red cell casts
Photosensitivity
Anti-nuclear antibodies
Immunological disorder (anti-dsDNA, anti-smith, antiphospholipid)
Neurological disorder - seizures, coma
