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INFECTIOUS DISEASES

INFECTIOUS DISEASES. INTRODUCTION. Infectious diseases have a predominant influence contributing to the disparities in child health between the developed & developing countries They are the chief cause of morbidity & chronic ill heath amongst children in Africa. MEASLES (RUBEOLA).

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INFECTIOUS DISEASES

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  1. INFECTIOUS DISEASES DR (MRS) M.B. FETUGA

  2. INTRODUCTION • Infectious diseases have a predominant influence contributing to the disparities in child health between the developed & developing countries • They are the chief cause of morbidity & chronic ill heath amongst children in Africa DR (MRS) M.B. FETUGA

  3. MEASLES (RUBEOLA) DR (MRS) M.B. FETUGA

  4. INTRODUCTION • Measles is an acute, highly contagious viral disease. • Important child health problem in Africa • A common and often fatal dx in developing countries. • Outstanding cause of morbidity among African children • Milder in children in developed countries & high SE in the tropics due to nutrition & SE status • WHO estimates there were 30 – 40 million cases and 745,000 deaths from measles in 2001. DR (MRS) M.B. FETUGA

  5. MEASLES VIRUS • Paramyxovirus, genus Morbillivirus. Single-stranded RNA virus. • There is only one antigenic type of measles virus. • Rapidly inactivated by heat, light, acidic pH, ether, and trypsin. • Short survival time (<2 hours) in the air, or on objects and surfaces. DR (MRS) M.B. FETUGA

  6. TRANSMISSION 1 • Measles occurs thro’out the world but the burden is in the developing world. • It is a human disease. No known animal reservoir or asymptomatic carrier. • Transmission is 1oly person to person via large respiratory droplets and aerosolized droplets. DR (MRS) M.B. FETUGA

  7. TRANSMISSION 2 • Highly communicable, with >90% 2o attack rates among susceptible persons. Maximum communicability occurs from onset of prodrome through the first 3–4 days of rash. • Malnutrition & overcrowding are two major factors predisposing to severe forms of the disease. DR (MRS) M.B. FETUGA

  8. INCIDENCE • Almost exclusively a disease of the under-5s in the developing world. • Peak incidence occurs in the 2nd year of life. • Rare in children < than 6 months in age due to the protection offered by maternally acquired anti-measles antibodies. DR (MRS) M.B. FETUGA

  9. INCIDENCE • By the age of 5 years, close to 100% of children in the developing world are already affected by measles. • Early contact with the virus in high dosage results from overcrowding of families in the tropics • This accounts for the early age of occurrence & severity of the infection • Males are more affected than females. DR (MRS) M.B. FETUGA

  10. PATHOGENESIS 1 • Measles is a disease of epithelial linings. The 1o site of infection is the respiratory epithelium of the nasopharynx. • Generalized mucosal inflammation • 2 to 3 days after invasion, a10 viraemia occurs with subsequent infection of the RES system. Multinucleated giant cells containing inclusion bodies are xteristic. DR (MRS) M.B. FETUGA

  11. PATHOGENESIS 2 • Following further viral replication in regional and distal RES sites, a 20 viraemia occurs 5 to 7 days after initial infection. • During this viraemia, there may be infection of the respiratory tract and other organs. Measles virus is shed from the nasopharynx beginning with the prodrome until 3–4 days after rash onset. DR (MRS) M.B. FETUGA

  12. CLINICAL FEATURES 1 • IP from exposure to prodrome averages 10–12 days. • Prodrome lasts 2–4 days (range 1–7 days). • Xterized by fever, which ↑ses in stepwise fashion, often with peak as high as 39°C. DR (MRS) M.B. FETUGA

  13. CLINICAL FEATURES 2 • This is associated with the onset of coryza (runny nose) • cough- brassy& husky due to laryngeal & tracheal involvement • conjunctivitis (photophobia), lacrymation, sneezing. DR (MRS) M.B. FETUGA

  14. CLINICAL FEATURES 3 • Koplik’s spots, a rash (enanthem) present on mucous membranes, is pathognomonic for measles. Appears on 3rd or 4th day of prodromal period; 1–2 days b/4 the rash usually with intense buccal hyperaemia. The spots appear as punctuate blue-white spots on the bright red background of the buccal mucosa opposite the lower molar teeth. The spots may also be found on the conjunctivae. DR (MRS) M.B. FETUGA

  15. CLINICAL FEATURES 4 • On or about the 4th day of the illness, the measles rash appears at the peak of resp symptoms when the temp is quite high(39oC & above)-temp rises abruptly as the rash appears & often reaches 40-450C • Morbilliform- ‘measles-like’ because it is so xteristic • Blotchy, erythematous maculopapular eruption that usually lasts 5–6 days. Begins behind the ears & at the hairline on forehead, then rapidly involves the face and upper neck. During the next 3 days, the rash gradually proceeds downward and outward, reaching the hands and feet. DR (MRS) M.B. FETUGA

  16. CLINICAL FEATURES 5 • In uncomplicated cases when the rash appears on the legs & feet, symptoms subside rapidly, usually with abrupt temperature drop • Persistence of fever beyond 3-4/7 of exanthem indicates onset of complications • The maculopapular lesions are confluent mainly on face & trunk but remain discrete on lower extremities. DR (MRS) M.B. FETUGA

  17. CLINICAL FEATURES 6 • Severity of disease is related to extent & confluence of the rash • Mild - tends not to be confluent • Severe- confluent & extends to palms, soles • Itching is generally slight DR (MRS) M.B. FETUGA

  18. Full-blown measles rash with conjunctivitis DR (MRS) M.B. FETUGA

  19. CLINICAL FEATURES 7 • The rash fades in the same order that it appears, from head to extremities leaving a branny desquamation of the skin. Fine desquamation occurs over more severely involved areas. In malnourished children, the desquamation is more severe and persists for several weeks. • Other symptoms of measles include anorexia, vomiting, diarrhea, especially in infants, and generalized lymphadenopathy. DR (MRS) M.B. FETUGA

  20. Measles rash with exfoliation DR (MRS) M.B. FETUGA

  21. CLINICAL FEATURES 8 • LN- < angle of jaw, post cervical – usually • Mesenteric LN may cause abd pain which may simulate appendicitis • Slight splenomegaly DR (MRS) M.B. FETUGA

  22. DIAGNOSIS • Diagnosis is clinical • Measles is rarely subclinical • Leucopenia; relative lymphocytosis • CSF encephalitis- ↑protein & small ↑ in lymphocytes, normal glucose DR (MRS) M.B. FETUGA

  23. RESPIRATORY COMPLICATIONS • Bronchopneumonia - most frequent and may be 1o (Viral- multinucleated giant cell esplly in malnourished ) or 2o (Bacterial- rash has subsided). • Obstructive laryngitis (Croup). • Empyema. • Pneumothorax. • Subcutaneous emphysema. • Otitis media. • Reactivation of TB focus- due to↓CMI in measles; tuberculin test is usually –ve up to 3/12 after measles DR (MRS) M.B. FETUGA

  24. GASTROINTESTINAL COMPLICATIONS • Diarrhoea- lactose intol, protein-LE, malnutrition • Stomatitis • Severe anorexia • Dehydration • Severe malnutrition particularly kwashiorkor- anorexia, stomatitis, nasal block, diarrhoea,↑ catabolism • Cancrum oris. DR (MRS) M.B. FETUGA

  25. OTHER COMPLICATIONS • Eye: Keratitis; Xerophthalmia; Blindness. • Cardiac: Myocarditis and Congestive cardiac failure. ECG changes- T wave inversion, prolonged P-R interval Haematologic: thrombocytopenic purpura vascular damage DIC→Bleeding tendencies. DR (MRS) M.B. FETUGA

  26. CNS COMPLICATIONS 1 • Febrile convulsion • Acute encephalitis – Onset generally occurs 6 days after rash onset (range 1–15 days), xterized by fever, headache, vomiting, stiff neck, meningeal irritation, drowsiness, convulsions, and coma. CSF-pleocytosis and elevated protein. CFR is approximately 15% and residual neurologic damage may occur in as many as 25%. DR (MRS) M.B. FETUGA

  27. CNS COMPLICATIONS 2 Subacute sclerosing panencephalitis (SSPE) Rare degenerative CNS disease believed to be due to persistent measles virus infection of the brain. Average onset occurs 7 years after measles (range 1 month-27 years) Occurs in 5-10 cases per million reported measles cases. Affects males predominantly. Insidious onset with progressive deterioration of behavior and intellect, followed by ataxia, myoclonic seizures, and eventually death. DR (MRS) M.B. FETUGA

  28. CLINICAL FORMS OF MEASLES 1 Atypical measles occurs only in persons who received inactivated (“killed”) measles vaccine (KMV) and are subsequently exposed to wild-type measles virus. KMV sensitized the recipient to measles virus antigens without providing protection. Subsequent infection with measles virus leads to signs of hypersensitivity polyserositis. DR (MRS) M.B. FETUGA

  29. CLINICAL FORMS OF MEASLES 2 Atypical Measles :Xterized by fever, pneumonia and pleural effusions. Koplik spots rarely appear. Rash usually maculopapular or petechial, but may have urticarial, purpuric, or vesicular components. Appears first on the wrists or ankles. Atypical measles may be prevented by revaccinating with live measles vaccine. Moderate to severe local reactions with or without fever may follow vaccination; these reactions are less severe than with infection with wild measles virus. DR (MRS) M.B. FETUGA

  30. CLINICAL FORMS OF MEASLES 3 Modified measles: Occurs 1oly in partially immunized pts who received immune globulin (IG) as post-exposure prophylaxis and in young infants < 1year who have some residual maternal antibody. Usually xterized by mild illness that ffgs usual sequence of measles infection: a prolonged IP, mild/shorter prodrome, milder symptoms, absent or few Koplik spots and sparse, discrete rash of short duration. Similar mild illness has been reported among previously vaccinated persons. DR (MRS) M.B. FETUGA

  31. CLINICAL FORMS OF MEASLES 4 Severe Measles: Usually xterized by confluent rash; extension of the rash to the palms and soles and dark-appearing rash (hemorrhagic OR black measles –hemorrhage into the dermis). Dose of infectious particle has a bearing on severity. Xterized by high fever (105°–106°F), seizures, delirium, respiratory distress, and hemorrhage into the skin and mucous membranes. DR (MRS) M.B. FETUGA

  32. DIFFERENTIAL DIAGNOSES 1 • Rubella (German Measles)- mild prodrome, LN enlargement (post. Auricular& post. ∆ of neck), rashes < striking • Roseola infantum (exanthem subitum) – rash appears as fever disappears • Enteroviral infections- < fever & rash < striking • Meningococcaemia- rash similar to measles (petechial, purpuric) DR (MRS) M.B. FETUGA

  33. DIFFERENTIAL DIAGNOSES 2 • Scarlet fever- papular with ‘gooseflesh’ texture on erythematous base • Drug eruptions (Penicillins & Sulphonamides) • Infectious mononucleosis- enlarged peripheral LN • Kawasaki disease - Rickettsia – rash spares face usually DR (MRS) M.B. FETUGA

  34. INVESTIGATIONS • Diagnosis of measles is clinical • Viral culture to isolate the Measles virus • Serology: Detection of IgM and IgG anti-measles antibodies. • FBC – leucopenia, thrombocytopenia. • Serum E-, urea and creatinine – diarrhoea and dehydration • CXR- pneumonia, TB. • CSF analysis. • Electrocardiography. • Surface swabs (ear swab) for m/c/s. DR (MRS) M.B. FETUGA

  35. MANAGEMENT • Restore & maintain fluid, E- & caloric intake. • No specific antiviral therapy; treatment is entirely supportive. Antipyretics for fever, bed rest, and control of convulsions. • Humidification of the room may be necessary for those with laryngitis or an excessively irritating cough. • Eye toileting & care of sore mouth are also important. • Vitamin A: Recommended regimen - 100,000IU orally for children 6mo to 1yr & 200,000IU for children >1yr of age. Additional doses should be given on days 2 and 3. • AB-only indicated for obvious bacterial infections like otitis media and pneumonia. Prophylactic antibiotic use is not indicated in measles. DR (MRS) M.B. FETUGA

  36. PROGNOSIS • Although measles is a major cause of childhood morbidity and mortality, most children recover uneventfully. • Prognosis is worse in the presence of malnutrition, immunosuppression and when it is acquired from a sibling in an overcrowded environment. • Case fatality rates vary between 2 and 10%. • Other sequelae of measles include blindness, deafness, CNS deficits and disability from cancrum oris. DR (MRS) M.B. FETUGA

  37. MEASLES VACCINATION • Vaccine – preventable disease • The Schwarz Measles vaccine - widely used in the developing world. • It is an attenuated live vaccine recommended for use at the age of 9 months. • Waning transplacental passive immunity by > 90% of children by 9 months determines age of measles vaccine DR (MRS) M.B. FETUGA

  38. MEASLES VACCINATION • Measles antibodies develop in approximately 95% of children vaccinated & it confers life long immunity like the natural infection. • Triple vaccine MMR (Measles Mump Rubella)- used in the developed world. DR (MRS) M.B. FETUGA

  39. POSTEXPOSURE PROPHYLAXIS • Immune globulin (IG) may prevent or modify disease and provide temporaryprotection if given within 6 days of exposure. • Dose is 0.25 mL/kg body weight but 0.5 mL/kg for immunocompromised persons. DR (MRS) M.B. FETUGA

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