INFLUENZA INFECTION By M Osama Hussein. MD

Credit: L. Stammard, 1995

• RNA, enveloped

• Viral family: Orthomyxoviridae

• Size: 80-200nm or .08 – 0.12 μm (micron) in diameter

• Three types• A, B, C

• Surface antigens• H (haemaglutinin)• N (neuraminidase)

Influenza Virus

H1 N1H2 N2H3 N3H4 N4H5 N5H6 N6H7 N7H8 N8H9 N9

H10H11H12H13H14H15H16

Haemagglutinin subtype Neuraminidase subtype

Epidemic – a located cluster of casesPandemic – worldwide epidemicAntigenic drift

◦ Changes in proteins by genetic point mutation & selection

◦ Ongoing and basis for change in vaccine each year

Antigenic shift ◦ Changes in proteins through genetic

reassortment◦ Produces different viruses not covered by

annual vaccine

Definitions

Influenza The Normal Burden of Disease

Seasonal Influenza◦ Globally: 250,000 to 500,000 deaths

per year◦ In the US (per year)

~35,000 deaths >200,000 Hospitalizations $37.5 billion in economic cost

(influenza & pneumonia) >$10 billion in lost productivity

Pandemic Influenza◦ An ever present threat

Reassortment in Pigs

Swine Influenza A(H1N1) Transmission Through Species

Swine Influenza A(H1N1) Global Response

Source: WHO

Source: WHO

Influenza Symptoms

Influenza (also known as the flu) is a

contagious respiratory illness caused by flu

viruses. It can cause mild to severe illness, and

at times can lead to death. The flu is different

from a cold. The flu usually comes on suddenly.

Influenza SymptomsFever* or feeling feverish/chills

Cough

Sore throat

Runny or stuffy nose

Muscle or body aches

Headaches

Fatigue (tiredness)

Vomiting and diarrhea, children

Swine Influenza A(H1N1) Guidelines for General Population

Covering nose and mouth with a tissue when coughing or sneezing◦ Dispose the tissue in the

trash after use. Handwashing with soap and

water◦ Especially after coughing or

sneezing. Cleaning hands with alcohol-

based hand cleaners Avoiding close contact with

sick people Avoiding touching eyes, nose

or mouth with unwashed hands

If sick with influenza, staying home from work or school and limit contact with others to keep from infecting them

Recommendations for Prevention and Control of Influenza in Children, 2016–2017

COMMITTEE ON INFECTIOUS DISEASES

PediatricsSeptember 2016From the American Academy of PediatricsPolicy Statement

1. Annual universal influenza immunization is indicated with either a trivalent or quadrivalent (no preference) inactivated vaccine.

2. The 2016–2017 influenza A (H3N2) vaccine strain differs from that contained in the 2015–2016 seasonal vaccines. The 2016–2017 influenza B vaccine strain (Victoria lineage) included in the trivalent vaccine differs from that contained in the 2015–2016 seasonal trivalent vaccines (Yamagata lineage).

3. Quadrivalent live attenuated influenza vaccine (LAIV4) should not be used in any setting during the 2016–2017 influenza season in light of the evidence for poor effectiveness of LAIV4 in recent seasons, particularly against influenza A (H1N1)pdm09 viruses.

4. All children with egg allergy can receive influenza vaccine with no additional precautions from those of routine vaccinations.

5. All HCP should receive an annual influenza vaccine, a crucial step in preventing influenza and reducing health care–associated influenza infections. Because HCP may care for or live with people at high risk of influenza-related complications, it is especially important for them to get vaccinated annually.

6. Pediatricians should attempt to promptly identify children suspected of having influenza for rapid antiviral treatment, when indicated, to reduce morbidity and mortality.

Prevention and Control of Seasonal Influenza with Vaccines

Recommendations of the Advisory Committee on Immunization Practices — United States, 2016–17 Influenza Season

August 26, 2016 / Grohskopf, et alRoutine annual influenza vaccination is

recommended for all persons aged ≥6 months who do not have contraindications.

live attenuated influenza vaccine (LAIV4) should not be used.

No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is otherwise appropriate.