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• What are the learning objectives of the study material?

  • Impact and aetiology of Chlamydia sp (e.g., C. trachomatis)
  • Impact and aetiology of Rickettsia sp (e.g., Rickettsia prowazekii)
  • Understand their unique life cycle and intracellular survival

  
• What family did Chlamydia and Chlamydophila once belong to?


  They once belonged to the same family.
• What is the single genus that Chlamydia and Chlamydophila are classified under now?


  Chlamydia
• Name one example of Chlamydia sp that causes ocular and genital infections.


  1. trachomatis
• What disease is caused by C. psittaci?


  Psittacosis
• What percentage of community-acquired pneumonia (CAP) is attributed to C. pneumoniae?


  10-20%
• What is the elementary body (EB) in Chlamydia?


  It is the infectious form that is metabolically inactive.
• What is the approximate size of elementary bodies (EB) in Chlamydia?


  Approximately 0.2-0.3 microns in diameter
• What are reticular bodies (RB) in Chlamydia?


  They are the intracellular reproductive form that is metabolically active.
• What is the size range of reticular bodies (RB) in Chlamydia?


  Approximately 0.5-2 microns in diameter
• How do reticular bodies (RB) reproduce?


  They can divide by binary fission resulting in new RBs.
• What type of cells do Chlamydia inhabit?


  Epithelial cells and macrophages
• Why are Chlamydia small enough to pass through 0.45 micron filters?


  Because they are non-motile, obligate intracellular coccoid bacilli.
• What is the significance of peptidoglycan in Chlamydia?


  Its existence was debated until a new metabolic cell-wall labeling method revealed it in C. trachomatis.
• What type of pathogens are Chlamydia classified as?


  Obligate intracellular pathogens
• What is the public health impact of Chlamydia?


  It is responsible for blindness or visual impairment in about 1.9 million people.
• How many people live in trachoma endemic areas?


  142 million people
• What does the SAFE strategy stand for in relation to trachoma prevention?


  • Surgery
  • Antibiotics
  • Facial cleanliness
  • Environmental improvement
• How many people received surgery for trachoma in 2018?


  146,112 people
• What was the global-level antibiotic coverage for trachoma in 2018?


  50%
• What is the most common preventable cause of blindness?

  Chlamydia trachomatis
• What types of infections does Trachoma (types A, B, and C) cause?


  Infection of conjunctival epithelial cells
• What can repeated clinical/subclinical infection of Trachoma lead to?


  Clouding or scarring of the cornea
• How is Trachoma transmitted?


  By flies, fomites, and touch
• What type of climate does Trachoma favor?


  Hot, dry climates
• What is inclusion conjunctivitis associated with?


  Sexual contact and contaminated swimming pools
• What is the neonatal form of inclusion conjunctivitis?


  It can develop when an infant is in the birth canal and appears 5-12 days after birth.
• What can the neonatal form of inclusion conjunctivitis precede?


  Infant pneumonia
• What are the symptoms of genital chlamydiasis in men?


  Urethritis, mild burning, and white discharge from the penis
• What are the symptoms of genital chlamydiasis in women?


  Urethritis, cervicitis, PID, and infertility
• What is psittacosis also known as?


  Parrot fever
• From which species is Chlamydia psittaci isolated?


  Over 100 avian species, especially cockatiels and parakeets
• How long can the elementary bodies (EB) of Chlamydia psittaci remain resistant in feed?


  Up to 2 months
• What is the typical onset time for symptoms in patients with psittacosis?


  Most patients develop symptoms after 10 days
• Who are at risk for developing psittacosis?


  Pigeon farmers, pet shop owners, veterinarians, and poultry workers
• What are the four genera of Rickettsia mentioned in the study material?


  • Rickettsia
  • Orientia
  • Coxiella
  • Erlichia
• What are the general features of Rickettsiae?


  They are obligate intracellular pathogens, small coccoids or rods, and multiply by binary fission only in infected cells.
• What is the size of Rickettsiae?


  0.3 by 1-2 microns
• How are Rickettsiae transmitted?


  By arthropod vectors such as ticks, mites, lice, and fleas
• What disease is caused by Rickettsia prowazekii?


  Typhus