1. General
    2. 1. Man and Medicine: Towards health for all
    2. Concept of Health and Disease
  2. Epidemiology
  3. Screening for disease
  4. Communicable Diseases
    5. 3. Intestinal infections
    4. Respiratory infections
    5. Arthropod-borne infections
    6. Zoonoses
    7. Surface infections
    8. Emergining and re-emergining infectious diseases
    9. Hospital acquired infections
Communicable Diseases
4. Respiratory infections
SMALLPOX (VARIOLA)
CHICKENPOX (VARICELLA)
MEASLES (RUBEOLA)
Image 1
Challenges for Measles elimination
  1. Weak immunization systems
  2. High infectious nature of measles
  3. Inaccessible populations due to conflict
  4. Increased immunization refusal group of people
  5. Changing epidemiology of measles
    • •
      This has led to increased transmission among adolescents and adults
  6. Need to provide catch-up measles vaccination
  7. Gaps in human and financial resources at the country, regional and global levels
Epidemiological determinants
Agent factors
▢ Agents: RNA paramyxovirus
▢ Source of infection:
  1. Only source of infection is Case of measles
  2. No carriers
▢ Infective material:
  1. Secretions of the nose, throat and respiratory tract of a case of measles.
▢ Communicability: 4 days before and 4 days after the appearance of the rash
▢ Secondary attack rate:
    Host factors
    ▢ Age:
    ❖ Developing country: 6 months and 3 years of age
    ❖ Developed country: Over 5 years
    ▢ Sex: Equal incidence
    ▢ Immunity: Life-long immunity by 1st attack.
    ▢ Nutrition:
    • •
      Severe in malnourished child (400 times higher than well-nourished child)
    Environmental factors
      Transmission
      Incubation period
      ▢ From exposure to onset of fever: 10 days
      ▢ From exposure to onset of rash: 14 days
      ▢ Artificially induced bypassing the respiratory tract (as with injection of live measles vaccine): 7 days
      Clinical factors
      Prodromal stage
      ▢ Timing:
      1. Between fever and rash
      2. Begins 10 days after infection and lasts until day 14
      ▢ Characteristic:
      ❖ Fever:
      ❖ Coryza with sneezing and nasal discharge:
      ❖ Cough:
      ❖ Redness of eyes:
      ❖ Lacrimation and often photophobia:
      ❖ Vomiting or Diarrhoea:
      ❖ Koplik's spots:
        Image 1
      1. It is like table salt crystals.
      2. They are small, bluish-white spots on a red base, smaller than the head of a pin.
      3. It is present on the buccal mucosa opposite the first and second lower molars.
      4. It appears 1 or 2 days before the appearance of the rash.
      5. It is pathognomonic of measles.
      Eruptive stage
      This phase is characterized by the appearance of Rash.
      ▢ Rash:
      1. The rash is typical, dusky-red, macular or maculo-papular.
      2. It begins behind the ears and spreads rapidly in a few hours over the face and neck, and extends down the body taking 2 to 3 days to progress to the lower extremities.
      3. They may remain discrete, but often becomes confluent and blotchy.
      4. The lesions and fever disappear in another 3 or 4 days signalling the end of the disease.
      5. The rash fades in the same order of appearance leaving a brownish discoloration which may persist for 2 months or more.
      6. The rash develops as the interaction of immune T cells with virus-infected cells in the small blood vessels. Hence no rash develops in patient with defective cell-mediated immunity.
      ▢ Antigen-antibody:
      1. The virus is present in tears, nasal and throat secretions, urine and blood in the prodromal and eruptive stage.
      2. Just as the maculo-papular rash appears, the circulating antibodies become detectable, the viraemia disappears and the fever falls.
      Post-measles stage
      1. It is the resolving stage.
      2. Weight-loss
      3. Weakness for a number of days
      4. Failure to recover and a gradual deterioration into chronic illness
      5. Growth retardation and Diarrhoea
      6. Cancrum oris
      7. Pyogenic infections
      8. Candidosis
      9. Reactivation of pulmonary tuberculosis
      Complications
      ▢ Common complications:
      1. Otitis media
      2. Laryngotracheo-bronchitis (croup)
      3. Diarrhoea and Dehydration
      4. Pneumonia
      5. Post-infectious measles encephalitis
      6. Sub-acute sclerosing panencephalitis (SSPE)
      ▢ Measles during pregnancy:
      1. It is not known to cause any congenital abnormalities of the foetus.
      2. However, it is associated with spontaneous abortion and premature delivery.
      Diagnosis
      ▢ Clinical diagnosis:
      1. It is detected clinically based on typical rash and Koplik's spots seen in oral mucosa.
      ▢ Molecular methods:
      1. Detection of specific IgM antibodies by ELISA
      2. Detection of measles virus RNA by RT-PCR in throat swabs, oral fluids or nasopharyngeal mucus or urine.
      Treatment
      No specific treatment for measles
      ▢ Supportive care:
        Relieving common symptoms such as
      1. Fever
      2. Cough
      3. Nasal congestion or Rhinorrhea
      4. Conjunctivitis
      5. Sore mouth
      ▢ Nutritional support: Reduces the risk of malnutrition due to diarrhoea, vomiting and poor appetite associated with measles.
      ▢ Breast-feeding: Should be encouraged.
      ▢ Oral rehydration salts: It prevents dehydration.
      ▢ Isolation:
      ▢ Vaccination:
      ▢ Vitamin A supplementation:
      MUMPS
      RUBELLA (GERMAN MEASLES)