Antigenic Shift and Drift

Antigenic Drift Nature of antigenic variation: Minor Mechanism: Gradual accumulation of amino acid substitutions due to point mutation in the hemagglutinin (H) and neuraminidase (N) genes. As mutations accumulate, antibodies generated by exposure to previous strains do not neutralize current strains to the same extent,… Read More

Rickettsial Diseases Mnemonic

Rickettsia is a gram negative obligate intracellular parasite. As shown in the table above, human is only an incidental host except in louse-borne epidemic typhus. Disease Agent Vectors Typhus group Epidemic typhus or Brill Zinsser disease R. prowazekii Louse Murine/Endemic typhus R.typhi (R.mooseri) Flea Spotted… Read More

Ethambutol Induced Optic Neuropathy

Mechanism of Ethambutol induced optic neuropathy Ethambutol is metabolized to a chelating agent. The chelating agent formed then may impair the function of metal-containing mitochondiral enzymes, such as the copper containing cytochrome-c oxidase of complex IV and the iron containing NADH:Q oxidoreductase of complex I.… Read More

Thoracocentesis : Practical Essentials

Absolute contraindications of thoracocentesis There are no absolute contraindications to diagnostic thoracocentesis. If clinical judgement dictates that the information gained from the pleural fluid analysis may help in diagnosis and therapy, thoracocentesis should be performed. Necessity of an immediate alternative procedure such as open thoracostomy… Read More