Whooping cough

Pertussis, also known as whooping cough is a highly contagious bacterial disease mainly caused by Bordetella pertussis.

1. WHOOPING COUGH Dr. Rajalekshmy.P.R Dept of Swasthavritta Amrita School of Ayurveda

2. INTRODUCTION Pertussis, also known as whooping cough is a highly contagious bacterial disease mainly caused by Bordetella pertussis. Clinically characterized by an insidious onset with mild fever and an irritating cough, gradually becoming paroxysmal with characteristic whoop often with cyanosis and vomiting. Also known as hundred day cough. Habit pattern of coughing may last for longer or subsequent weeks & months.

3. DERIVATION Following a fit of coughing a high-pitched whoop sound or gasp may occur as the person breathes in. The coughing may last for more than a hundred days or ten weeks. A person may cough so hard they vomit, break ribs, or become very tired from the effort. Children less than one year old may have little or no cough and instead have periods where they do not breathe .

4. PROBLEM STATEMENT Important cause of death of infants worldwide. Public health concern even in countries with high vaccination coverage. 2010- about 1.29 lac cases were reported to WHO globally. Most lethal disease of infants and young children who have not been immunized, particularly those with underlying malnutrition and other respiratory infections. India- Marked decline of disease after launch of UIP. 1987: incidence-1.63 lakh cases 2011- 39,091 cases (decline-76%)

5. AGENT Bordetella pertussis Gram negative organism Small, ovoid , cocobacillus . Length - 0.5 microns Have bipolar metachromatic granules when stained with Toludine blue. Occurs in smooth and rough phases, capsulated and non-capsulated forms.

6. Loose clumps of bacilli appear as thumb print appearence with clear space between the organisms. Freshly isolated strains have fimbria.

7. Clinical disease associated with encapsulated phase 1 strains. Carries 3 major agglutinogen - 1,2 and 3 and several minor ones. Bacterium survive only for very short periods outside the human body. In a small percent of cases, B. Parapertussis is responsible .

8. SOURCE OF INFECTION B.Pertussis infects only man. Source of infection is a case of pertussis. Chronic carrier does not exist.

9. INFECTIVE MATERIAL Infective bacilli occurs abundantly in the nasopharyngeal and bronchial secretions. Objects freshly contaminated by discharge are also infective.

10. INFECTIVE PERIOD Most infectious during catarrhal stage. Extends from a week after exposure to about 3 weeks after the onset of paroxysmal stage.

11. SECONDARY ATTACK RATE 90% in unimmunized household contacts.

12. HOST FACTORS SEX Incidence and fatality more among females than males. AGE Infants and pre-school children Highest incidence-below 5 yrs. Highest mortality-infants below 6 months. IMMUNITY Recovery from pertussis or adequate immunization is followed by immunity. Second attacks may occur in persons with declining immunity. Maternal antibodies does not appear to give them protection.

13. ENVIRONMENTAL FACTORS Occurs throughout the year. Disease shows seasonal trends with more cases in winter and spring due to overcrowding. Socio economic conditions and way of life influences epidemology .

14. MODE OF TRANSMISSION Spread through droplet infection and direct contact. Bacilli spread into air through cough, sneezes or talks.

15. INCUBATION PERIOD 7-14 days, but not more than 3 weeks.

16. PATHOGENESIS The bacterium contains a surface protein, filamentous haemagglutinin adhesin , which binds to the  sulfatides  found on cilia of epithelial cells. Once anchored, the bacterium produces tracheal cytotoxin , which stops the cilia from beating. This prevents the cilia from clearing debris from the lungs, so the body responds by sending the host into a coughing fit. These coughs expel some bacteria into the air, which are free to infect other hosts.

17. CLINICAL COURSE CATARRHAL STAGE Lasts for about 10 days Insidious onset, lacrimation, sneezing, coryza , anorexia, malaise, hacking night cough PAROXYSMAL STAGE Lasts for 2-4 weeks Bursts of rapid, consecutive coughs followed by deep, high pitched inspiration(whoop). Followed by vomiting Young infants- cyanosis and apnoea Adults & adolescent-persistent cough CONVALESCENT STAGE Lasts for 1-2 weeks Illness generally lasts for 6-8 weeks.

18. COMPLICATIONS Occurs in 5-6% cases, most frequent in infants less than 6 months. Complications-bronchitis, bronchopneumonia, bronchiectasis Violent paroxysm precipitate subconjunctival haemorrhage, epistaxis, haemoptysis and cerebral haemorrhage which may cause convulsions and coma. Broncho pneumonia occurs in 5.2% cases.

19. CONTROL CASES Early diagnosis, isolation and treatment of cases, disinfection of discharges from nose and throat Drug of choice- erythromycin dose-:30-50mg/kg of body weight in 4 divided doses for 10 days. Alternatives- ampicillin, septran or tetracycline CONTACTS Infants and young children should be kept away from cases. Known contacts should be given prophylactic antibiotic (erythromycin/ ampicillin) treatment for 10 days to prevent infecting bacteria become established .

20. ACTIVE IMMUNIZATION Combined DPT, DTwP or DTaP vaccines DPT vaccine-3 doses(0.5 ml) intramuscularly at one month interval, starting at 6 weeks. B ooster dose at 18-24 months. Acellular pertussis vaccines are used in older children and adults. Pertussis vaccination affects pharyngeal colonization resulting in reduction of bacterial transmission. Duration of protection: 6-12 years

21. CONTRA-INDICATIONS Anaphylatic reactions, H/O epilepsy, convulsions, CNS disorders, reaction to triple vaccine injections UNTOWARD REACTIONS Local reactions at site of injection Mild fever Irritability Persistent inconsolable screaming, seizures, anaphylactic reactions, encephalopathy

22. PASSIVE IMMUNIZATION Merits of immunoglobulins in pertussis has yet to be established. No evidence of its efficacy in controlled trials.