Pertussis

Pertussis

• 1.
  PERTUSSIS MADE BY: DIWAKARSHARMA B.Sc. BIOCHEMISTRY(H) 13/2004
• 2.
  DEFINITION: • Pertussis alsoknown as “whooping cough” is a highly contagious bacterial disease. • It is caused by the bacterium Bordetella pertussis. • This coughing may last for 10 or more weeks, hence the phrase ‘100-day cough’.
• 3.
  Signs & Symptoms •Paroxysmal cough • Inspiratory whoop • Hard to breathe • Syncope(temporary unconsciousness/faint) • Excessive cough may lead to vomiting, break of ribs, coughing fits and permanent brain injury. Incubation Period The time between exposure and the development of symptoms: 6-20 days Rare conditions : 42 days
• 4.
  HISTORY • B.Pertussis wasdiscovered in 1906 by Jules Bordet and Octave Gengou. • They also developed the first serology and vaccine. • The claimed rate of this disease is very low and the risk of death is very high
• 5.
  Epidemiology • Worldwide, whoopingcough affects 48.5m people yearly • It results in about 61k deaths in 2013 down from 138k deaths in 1990. • About 90% cases appear in developing countries. • This disease has even caused outbreaks in U.S. • And became the only vaccine- preventable disease that is associated with increasing deaths in U.S.
• 6.
  CAUSE: • Pertussis iscaused by the bacterium Bordetella pertussis. • It is an airborne disease which spreads easily through cough and sneezes of an infected person • Spread from Animals • There have been uncertainties about whooping cough as a zoonotic disease since around 1910. • But in 1930 that bacteria lost its virulent power due to repeatedly spread on agar media. • Today, some primates species are highly susceptible to B.pertussis and develop clinical whooping cough.
• 7.
  DIAGNOSIS Proper Technique forObtaining a Nasopharyngeal Specimen for Isolation of B pertussis FOR SEROLOGY
• 8.
  DIAGNOSIS Culture PCR DFASerology Specimen NP Swabs or aspirates NP Swabs or aspirates NP Swab Blood Advantages •Gold standard •100% Specific Results available quickly Rapid results Disadvantages •Relatively insensitive •Difficult to isolate •Most successful during the catarrhal stage •Takes 7-10 days to get the result •Sensitivity & specificity varies •Calcium alginate swabs cannot be used to collect NP swabs for PCR •Not confirmatory •No use for surveillance •No standardized test available •No use for Surveillance Comments Use with culture Use with culture and/or PCR Use with culture and/or PCR NP swab=nasopharyngeal swabs, PCR-Polymerase chain reaction, DFA-direct florescent antibody
• 9.
  CULTURE 1. Specimen obtainedby aspiration or swabbing the posterior nasopharynx. 2. Transfer specimen into a luki tube. 3. Specimens received must be cultured within 2 hours of collection. 4. Transport/Storage: Transport to the laboratory immediately at room temperature. Do not refrigerate. Refrigeration decreases the colony numbers by >75%.
• 10.
  PCR(polymerase chain reaction) •Specimens for PCR testing should be obtained by aspiration or swabbing the posterior nasopharynx. • Then PCR assays are done with IS481 or IS1001 gene as a target, which is commonly present in B.Pertussis • As in many cases this gene is susceptible to falsely- positive results so use of multiple targets may improve specificity of PCR assays for pertussis • At last the results are known to be positive by observing high cycle threshold (Ct) values • PCR has optimal sensitivity during the first 3 weeks of cough when bacterial DNA is still present in the nasopharynx. After the fourth week of cough, the amount of bacterial DNA rapidly diminishes, which increases the risk of obtaining falsely-negative results
• 11.
  DFA (Direct fluorescenceantibody) 1. Specimens are taken and placed in a sterile tube containing a small amount (0.5mL) of Casamino acids. 2. After vigorous mixing, 4 to 8 smears are prepared. 3. Layering of drops of material and allowing drying between drops should yield a smear with a visible film of material on it. 4. After drying and heat fixing, the slides may be stained.
• 12.
  PREVENTION • This diseasecan be prevented by vaccination: • DTaP (pediatric) ▫ approved for children 6 weeks through 6 years (to age 7 years) • Tdap (adolescent and adult) ▫ approved for persons 10 through 64 years (Boostrix) and 11 through 64 years (Adacel)
• 13.
  TREATMENT • Throughantibiotics: • Erythromycin(10-14 days) • Clarithromycin(6-8 days) • Azithromycin (3-5 days) • Microlidesare frequently recommended due to lower rates of side effects • Trimethoprim-sulfamethoxazole(TMP-SMZ) for those who are allergic to the antibioticsabove and in infants who have a risk of pyloric stenosis from microlides
• 14.
  BIBLIOGRAPGHY • www.google.co.in • en.wikipedia.org/wiki/Pertussis •www.cdc.gov/pertussis/ • Prescott, Harley,and Klein’s Microbiology