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Infectious Disease

Infectious Disease. Hugh Mc Gann Department of Infectious Diseases Seacroft Hospital. Assessment of patients with infections. History Examination Investigations. History. Specific symptoms e.g. fever, rigors, sweats Risk factors for infection Travel Infectious contacts Occupation

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Infectious Disease

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  1. Infectious Disease Hugh Mc Gann Department of Infectious Diseases Seacroft Hospital

  2. Assessment of patients with infections • History • Examination • Investigations

  3. History • Specific symptoms e.g. fever, rigors, sweats • Risk factors for infection • Travel • Infectious contacts • Occupation • Pets/birds • Sex/needles • Time since exposure/how long unwell • Previous medical problems/medications

  4. Investigations 1 • Baseline blood tests • Inflammatory markers: PV, ESR,CRP • LFTS • Culture things • Pus • Blood • Urine • Sputum • CSF • Biopsies

  5. Investigations 2 • Serology: Measure antibodies to specific infections IgG/IgM • Molecular methods • DNA amplification-PCR • Radiology • Plain X-rays • Ultrasound • CT/MRI • Isotope scans

  6. Immunity and Vaccination

  7. Immunity 1 • Innate Immunity • General or non specific host defences which provide the initial protection against microbes • Physical: skin, mucous membranes, intestinal tract, eye • Colonisation resistance by the normal flora • Mechanical removal: sneezing, coughing • Non-specific immune system: phagocytosis, complement, cytokines, natural killer cells

  8. Immunity2 • Specific immunity • Characterised by antigen specificity, memory and heightened response on subsequent antigen exposure • Humoral immunity: B cell receptors-Antibodies-activation of complement by classical pathway • Cell mediated immunity: T cell receptors-cytotoxic T cells

  9. The act of artificially inducing immunity or providing protection from disease Vaccines have led to the global eradication of smallpox, elimination of polio from western world and reduced incidence of many common disease Vaccination

  10. Vaccination 2 • Active Immunisation • A vaccine which stimulates body’s immune system to produce antibodies or cell mediated immunity • Live (attenuated infectious agents) Immunological response similar to that of natural infection. Life long immunity with one dose • Promote cell mediated immunity • MMR, polio(o), yellow fever

  11. Vaccination 3 • Active Immunisation • Inactivated (contain components of the organism or exotoxin) Diptheria, whooping cough, tetanus, HiB • Need repeated vaccinations and boosters to obtain high level/long lasting immunity • 1st(/2nd) injection produces slow antibody response-IgM • Subsequent injections give accelerated and higher level of antibodies IgG

  12. Vaccination 4 • Passive immunisation: short term protection by injecting human immunoglobulin. Immediate protection but only for a few weeks • Human normal immunoglobulin • Hepatitis A, measles • Specific immunoglobulin • Varicella zoster, hepatitis B

  13. Vaccination 5 • Childhood vaccine schedule • 3 doses at 2+3+4 months: HiB, DTP, Polio, Meningococcus group C • 12-15 months: MMR • 3-5 years: DT, Polio, MMR • 10-15 years DT, P, Polio • BCG

  14. Herpes viruses • Herpes Simplex Virus 1and 2 • Varicella Zoster • Cytomegalovirus • Epstein Barr (Infectious Mononucleosis) • Human Herpes Virus Type 6 and 7 • Human Herpes Virus Type 8(Kaposi sarcoma associated herpes virus)

  15. Herpes Simplex • HSV 1 and 2 cause clinically indistinguishable infection. • Primary infection: systemic illness • Gingivostomatitis and pharyngitis • Genital infection • Reactivation: • Genital HSV 2 more likely to reactivate • Oral-labial HSV 1 more likely to reactivate

  16. Varicella Zoster Virus 1 • Causes 2 distinct clinical diseases • Chicken Pox(varicella zoster) This is the primary infection. • Very contagious • Incubation period 10-14 days • Benign illness in children • Fever, vesicular rash, this then pustulates and scabs

  17. Varicella Zoster virus 2 • Shingles (Herper Zoster) reactivation of VZV which is latent in the dorsal root ganglia • Occurs in those who have had chickenpox, usually elderly • Vesicular rash with dermatomal distribution • H.Z. ophthalmicus, maxillary/mandibular V • Ramsay Hunt syndrome

  18. Infectious Mononucleosis 1 • Epstein Barr virus • Acute illness with sore throat (bilateral exudative tonsillitis), fever and lymphadenopathy • Ampicillin causes a rash in 90-100% • Palatal petechiae in up to 60% • Abnormal LFTs in 90%

  19. Infectious Mononucleosis 2 • Usually resolves within 2-3 weeks • Diagnosis by GFST (Paul-Bunell or monospot which detect heterophile antibodies • Atypical lymphocytes on blood film

  20. Childhood Rashes • Measles • Rubella • Scarlet Fever • Erythema Infectiosum • Exanthem Subitum

  21. Measles • Marked decrease in incidence since vaccine • Highly infectious, spread by droplets from respiratory secretions • Incubation period of 10 - 14 days • Diagnosis, clinical, confirmed by specific IgM in blood/saliva • Complications: pneumonia, encephalitis

  22. Measles Clinical features • Prodrome, malaise, fever, conjunctivitis and coryzal symptoms • Koplik’s spots: bluish grey grains on a red base on buccal mucosa opposite 2nd molars • Rash: purplish maculopapular, initially on the face, extends down the body • Illness lasts 7-10 days

  23. Scarlet Fever • Streptococcal infection- Group A Strep. • Streptococcal strain wgich produces an erythrogenic toxin • Pharyngitis • Rash on 2nd day of illness • Flushed face(circumoral pallor) • Strawberry tongue

  24. Rubella • Mild illness, often subclinical • Rubella virus first isolated in 1962, recognised clinically from 19th century • Spread: droplets from respiratory secretions • Usually primary school children. • Infection in pregnancy can cause foetal infection (congenital defects, foetal death)

  25. Rubella, Clinical Features • Incubation period 10-18 days • Rash: pink macular, face and trunk on day 1, limbs day 2, disappears day 3/4 • Lymphadenopathy: posterior cervical and sub occipital nodes • Conjunctival and pharyngeal injection • Diagnosis by specific rubella IgM

  26. Erythema Infectiosum • Often called slapped cheek or fifth disease • Caused by Parvovirus B19 • Facial rash sometimes preceded by mild fever • Rash: slapped cheek appearance, resolves in about 1 week but can recur with exposure to heat

  27. Exanthem subitum • Called roseola infantum or sixth disease • Caused by HHV-6 • Benign illness of infants/children • Rash preceded by 3-4 days of high fever, upper respiratory symptoms • Rash: maculopapular on trunk/limbs

  28. Mumps • Viral illness mostly in children/adolescents • Spread by droplets, incubation 2-4 weeks • Prodrome of fever, malaise, headache • Parotid gland enlargement (lifts ear up and out) usually bilateral, unilateral in 25% • May involve other salivary glands • Complications: orchitis and meningitis

  29. Whooping Cough 1 • Bordetella Pertussis • Higher incidence and increased severity in girls • Disease of childhood but now mostly seen in adults because of vaccination • Disease most severe in infants • Incubation period 1-3 weeks

  30. Whooping Cough 2 • Catarrhal phase: malaise, low grade fever, runny nose and eyes • Paroxysmal phase: typical cough-Whoop • Blood tests show high white cell count • Complications: secondary infection, physical sequelae of paroxysms of coughing

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