Influenza - Dx and Prevention

(Reference: 2000 Red Book)

Introduction: It seems difficult to believe that influenza is still a leading cause of morbidity and mortality when effective prophylaxis and treatment exists for this illness. Attack rates in children from 10% to 40% each year. 20-25 million visits and 20,000 deaths/yr in US

Clinical Manifestations: 1st symptoms: fever, chills, headache, malaise, myalgias, cough

Later symptoms: sore throat, nasal congestion, more prominent cough

Other possible symptoms: conjunctivitis, abdominal pain, nausea, vomiting, myalgias to the extent children cannot walk. Croup and pneumonia possible

Much more severe in neonates, sickle cell disease, BPD, asthma, CF, malignancies, diabetes, or chronic renal disease.

Incubation Period: 1 to 3 days.

Etiology: Influenza A, B and C. Influenza A strains subclassified by hemagglutinin subtypes and by neuraminidases. Influenza A: 65% cases; Influenza B: 35% of cases.

Epidemiology: Direct contact with large droplet infection or articles contaminated by secretions.

Spread most likely 24 hours before onset of symptoms and during peak symptoms.

Viral shedding usually lasts about 7 days.

Laboratory Tests for Influenza:

Gold Standard is the culture from nasopharyngeal secretions. Results in 2-6 days.
Serology: change in antibody titer between acute and convalescent sera.
Influenza A Rapid Test from B-D available in our lab; new test 2000: tests either A or B.
Biostar rapid test - FLU OIA49 (a 15 minute test) tests for both influenza A and B - waived.

Treatment: 3 Medications Possible to Use:

Amantadine/Ramantadine for Influenza A: not recommended under 1 year of age.
Dosage: 5 mg/kg/day up to 150 mg; if over 40 kg: 200 mg/day in 2 dosages. Give meds for up to 5 days or 48 hours after symptoms are gone. Treatment needs to be started within 48 hours of symptoms for meds to be effective.
Zanamivir: neuraminidase inhibitor of both type A and B-over 7 years of age; can be used for prophylaxis over the age of 5 years, however, so age may be changed soon (December 2001).
Oseltamivir: over the age of 13 years of age.

Prophylaxis of Influenza: Who Should Receive the Vaccine? Asthma, chronic pulmonary disease, heart disease, immunosuppressed disorders, HIV, Sickle cell, Other hemoglobinopathies, Diseases that require long-term aspirin therapy, diabetes, chronic renal disease, chronic metabolic disease, pregnancy. Some recent evidence that may be cost-effective to give all children influenza vaccine. (Cost: $70 per child if not vaccinated, $35-$66 if the child had shot)

Nasal vaccine 3 strains: type A H3N2, type A H1N1 and type B – FDA did not approve – 9/01

Two doses given 1 month apart when receiving vaccine the first time:

Age	Vaccine	Dose	Number of doses
6-35 months	split virus only	0.25cc	1-2
3-8 years	split virus only	0.5cc	1-2
9-12 years	split virus only	0.5cc	1
>12 years	Whole or split virus	0.5cc	1

Updated 9/01

Department of Pediatrics | Medical College of Georgia
Please email comments, suggestions or questions to:
John T. Benjamin M.D., jbenj@mcg.edu

February 27, 2004

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