Product D o s e / F o r m Active Ingredients Concen tra t io n
Cleensheen Liquid Maldison 0.5 per cent
Lice Rid Liquid Maldison 0.5 per cent
Nix Creme Rinse Liquid Permethrin 1.0 per cent
Quellada Creme Rinse Liquid Permethrin 1.0 per cent
Quellada Head Lice Treatment Liquid Permethrin 1.0 per cent
P e r t u s s i s
The catarrhal state may be indistinguishable from a viral upper respiratory tract infection.
The infection damages respiratory epithelium, producing respiratory obstruction and paroxysmal coughing, often with a characteristic whoop.
There is little fever.
Apnoea, seizures and encephalopathy may occur.
Infants aged less than six months and adults often do not have the characteristic whoop.
Paroxysms frequently end with the expulsion of clear, tenacious mucus, often followed by vomiting.
Pneumonia is the most common cause of death. Fatal encephalopathy, probably hypoxic, and inanition from repeated vomiting occasionally occur.
Case Definition
The case can be defined by:
• Isolation of Bordetella pertussis from a clinical speci-men.
or
• Elevated Bordella pertussis-specific IgA in serum, or B.
pertussis antigen in a nasopharyngeal specimen using immunofluorescence with a history of clinically compat-ible illness.
or
• An illness lasting two weeks or more with one of the following:
– Paroxysms of coughing.
or
– Inspiratory ‘whoop’ without other apparent causes.
or
– Post-tussive vomiting.
Public Health Significance and O c c u r re n c e
It is a distressing and often serious illness, particularly in children under one year of age.
The mortality rate is 0.5 per cent in infants under six months.
High immunisation levels reduce cases, and good nutrition and medical care reduce case fatality.
Many vaccinated adults may have asymptomatic infec-tion and act as a source of infecinfec-tion for younger children.
Method of Diagnosis
It can be diagnosed by:
• Elevated B. pertussis-specific IgA in serum.
• DFA identification of B. pertussis in nasopharyngeal specimens.
• Culture:
– The definitive diagnosis of B. pertussis infection relies on the culture of the organism from nasopharyngeal swabs.
– Unfortunately, the organism is fastidious and slow growing and its culture is usually complicated by contamination and overgrowth of other nasopharyn-geal organisms.
– Nasopharyngeal (not anterior nares) specimens should be taken with Dacron or calcium alginate swabs rather than cotton swabs.
– Patient specimens should be directly plated on selective transport media; for example, Charcoal agar, Regan-Lowe, Modified Stainer-Scholte agar, Fresh Bordet-Gengou medium.
– Isolation rates are highest in the first three to four weeks of illness. Prior antibiotic treatment will mark-edly decrease the detection rate.
• Fluorescent antibody tests:
– Direct fluorescent antibody identification of B. pertus-sis in nasopharyngeal specimens is a useful tech-nique.
– This needs good reagents and experienced person-nel.
– False negative and false positive results occur.
– These tests are particularly useful in situations later in disease or during antimicrobial therapy when viable organisms are no longer present.
• Other tests:
– Polymerase Chain Reaction (PCR).
– Serology, anti-B. pertussis IgA, IgG or IgM may be utilised in diagnosis. The role of these studies in clinical practice remains to be clarified.
Rese rvoir
Humans only.
Mode of Transmission
It is transmitted primarily by direct contact with dis-charges from respiratory mucous membranes of infected persons by the airborne route, probably droplet spread.
Adults and older siblings may be infected despite adequate vaccination, and may transmit infection without clinical disease.
Incubation Period
It is commonly seven to 10 days; rarely more than 14 days.
Thereafter, communicability decreases and becomes negligible in about three weeks.
When treated with erythromycin, the period of infectivity usually lasts five days or less after commencement of therapy.
Susceptibility and Resistance
Young infants are at risk of disease as there is poor placental transfer of immunity.
Severity is greatest in young infants; milder and atypical cases occur in all age groups.
Incomplete immunisation or waning immunity results in cases occurring in older children and adults.
There may not be lifelong immunity, even after clinical disease.
Control of Case
The suspected case should be excluded from the presence of others outside the home (especially young children and infants) until the patient has received more than five days of a minimum 14-day course of antibiotics.
Antibiotics: Erythromycin shortens the period of commu-nicability. Antibiotics do not reduce symptoms unless they are given during the incubation period or early in the catarrhal stage of the disease. (A 14-day course of co-trimoxazole should be given if erythromycin is contraindi-cated.)
Antibiotics should be given if case has been coughing less than three weeks.
Note
This is in accordance with NH&MRC guidelines for school exclusion. The Infectious Diseases Regulations in Victoria will be amended accordingly.
Control of Contacts
Vaccination:
• Protection is not afforded by passive immunisation.
• Close contacts under eight years of age who have not received five doses of DTP should be given a DTP dose as soon after exposure as possible.
Antibiotics: A 14-day course of erythromycin for house-hold or other close contacts, regardless of immunisation status, is recommended. Erythromycin should be given as soon as possible. It should be given no later than 14 days after the recipient’s first contact with the primary case during the infectious period (in high-risk household exposure settings, chemoprophylaxis may be considered for up to 21 days).
Exclusion: Inadequately immunised household contacts under eight years old should be excluded from school and child care centres until cases and contacts have received a minimum of five days of a 14-day course of erythromycin.
Investigation: A search for early, missed and atypical cases is indicated where a non-immune infant or young child is, or might be, at risk, in school. Check immunisa-tion status of close contacts.
Note
Close contacts may include all children in a child care centre, or all children in the same school classroom.
Please contact the Department of Human Services for further advice.
Preventive Measures
• Educate the public to the dangers of whooping cough and the advantages of initiating immunisation at two months of age and adhering to the immunisation schedule (DTP at two, four, six and 18 months and five years).
• Delay immunisation only for significant intercurrent infection or evolving neurological disorder. Minor URTI is not a contraindication to immunisation.