Swine Influenza H1N1

موضوع: Swine Influenza H1N1 الثلاثاء مايو 18, 2010 6:53 am

Swine Influenza

It is a highly contagious acute respiratory disease of pigs caused by one of several swine influenza A viruses , most commonly of the H1N1 subtype ( other subtype HIN2, H3N1, H3N2)

Pigs can be infected by more than one virus type at a time which allow the genes from these viruses to mix and lead to a virus with genes from a number of sources called a reassortant virus

Swine influenza virus

n Virus 2009 H1N1 influenza virus is a quadruple reassortment with gene products from :

Pigs ( Europe & Asia origin )

Avian influenza

Human influenza strains

n Swine influenza virus can be transmitted to humans via contact with infected pigs or environments contaminated with swine influenza viruses

n Infected man can spread the virus to other humans in the same way as seasonal influenza is spread

Outbreak of swine flu in humans

n 1918 Spanish influenza pandemic infect one third of the world's population and 50 million deaths

n 1930 H1N1 was isolated from pigs & humans

n 1976 outbreak of swine flu in Fort Dix, New Jersey involve 200 cases lead a national campaign for immunization of 40 million people with A/New Jersey /1976/ H1N1 vaccine

n From 2005 until 2009 , 12 human cases of swine flu were reported in the U.S

n In the current 2009 outbreak in the U.S the virus is described as a new subtype of influenza A/H1N1 not previously detected in pigs or humans

Current H1N1 influenza outbreak

n In 2009 cases of influenza were first reported in Mexico on March 18 which confirmed as HINI influenza A

n On May 2009 nearly 600 H1N1 confirmed in Mexico, including 25 deaths

n On April 2009 two cases were reported in California and a national public health emergency involving H1N1 was initiated at U.S

n By June 2009 , 27,717 lab –defined cases of H1N1 has been confirmed in U.S

n On 11/ June 2009 , WHO raised the pandemic alert to phase 6 indicating a global pandemic

Pandemic influenza phases

n On September 2009 , WHO reported that H1N1 is confirmed in over 200,000 people in more than 100 countries & at least 2185 deaths

Morbidity &Mortality

n H1N1 influenza tends to cause high morbidity but low mortality rates

n mortality rate 1% - 4%

Infectious period

n A confirmed case is defined to be infectious from one day prior to the onset of symptoms to 7 days after onset

n Incubation period is 1-4 days & possibly up to 7 days

n The duration of illness is typically 4 – 6 days

Symptoms of H1N1 influenza

n Manifestations of H1N1 influenza are similar to seasonal influenza

CDC definition of cases

n Influenza like illness ( ILI ) if there is fever ≥ 37.8 C plus cough & or sore throat

n Acute respiratory illness ( ARI ) ,the presence of 2 of 4 symptoms : fever , cough , sore throat , or rhinorrhea

Patients with 2009 influenza A H1N1

n Most cases have mild symptoms

n Higher rate of gastrointestinal symptoms & lack of fever

H1N1 influenza in children

n In children signs of sever disease include apnea ,tachypnea , dyspnea , cyanosis, dehydration, altered mental status , and extreme irritability

Patient with H1N1 influenza

n H1N1 can cause sever viral pneumonia in previously healthy people

n 40% of sever cases are occurring in previously healthy adult ( younger than 50 years ) & children

Clinical deterioration of patients with H1N1 influenza

n In sever cases patients begin to deteriorate around 3 to 5 days after symptoms onset

n Deterioration is rapid with many patient progressing to respiratory failure within 24 hours

n It require immediate admission to an intensive care unit & mechanical ventilation

Causes of Clinical deterioration of patients with H1N1 influenza

n Primary viral pneumonia which does not respond to antibiotic ,is the most common finding in sever cases & a frequent cause of death

n And the failure of multiple organs , including the heart , kidneys, & the liver

n Bacterial Co infection with H1N1 (found in approximately 30% of fatal cases) mostly with staphylococcal aureus & streptococcal pneumoniae bacteria

Complication of H1N1

n Exacerbation of underlying chronic dis.

n URT complication as : Sinusitis or otitis

n Pulmonary complication including asthma

n Secondary bacterial pneumonia

n Miscellaneous condition:

cardiac ( myocarditis & pericarditis )

myositis, CNS complication

H1N1 Mortality

H1N1 Influenza Reverse Seasonal Flu Mortality

q In normal flu season, 90% of deaths are in elderly people

q Since September , 88% of deaths in people under age 65 with almost ¼ th of deaths in young people under age of 25 years

High risk group

The Top 3 groups of increased risk for sever illness & death ,are :

Ø Children younger than 2 years of age

Ø Pregnant women ( especially during 1^st trimester ) & those up to 2 weeks after delivery or miscarriage

Ø people with underlying chronic lung disease including asthma

Ø Adult more than 65 years old

Ø Patient with chronic medical conditions including immune system problems , D.M

The CDC Criteria for suspected cases

Onset of acute febrile illness within 7 days of either

n Close contact with person who has a confirmed case of H1N1 influenza A virus

n Travel to a community where one or more H1N1 influenza A cases have been confirmed

n In a person who resides in a community where at least one H1N1 influenza case has been confirmed

Action to be done for suspected cases

n A respiratory ( throat) swap should be taken for H1N1 influenza testing ( to be placed in a refrigeratorif not send directly to the laboratory )

Treatment

n Treatment is largely supportive and consist of

n Bed rest, increased fluid consumption

n Cough suppressant and antipyretics & analgesics for fever & myalgia

n Sever cases may require intravenous hydration & other supportive measures

Instructions for H1N1 influenza patients

Patients should be encouraged to

n Stay at home during their illness for 7days or at least 24 hours after symptoms resolved

n To avoid contact with people who are sick

n To wash their hands frequently

n To avoid touching their eyes & mouth

The Action recommended by CDC In community with confirmed cases

n Contact their health provider to report illness

n Patient with difficulty of breathing or shortness of breath or severely ill should seek immediate medical care

n If the patient go into the community , he should wear a face mask

n While In home isolation :

- patient & other household member should be given infection control instructions

- should wear a face mask when within 6 feet of others at home

For household contacts who are not ill :

n Remain home at the earliest sign of illness

n Minimize contact in the community

n Designate a single household family member as a caregiver

School and child care closure

n Strong consideration to close schools upon confirmed case of H1N1 or a suspected case linked to a confirmed case

n If no additional confirmed or suspected cases closure for a period of 7 days

In community avoid large gathering

Preventive measures for health care personnel

n Place patients in a single room with the door closed

n Air exhausted directly outside

n Patients should wear a surgical mask when outside their room

n Encourage patient to wash their hands frequently & follow hygiene practices

n Routine cleaning & disinfection

n Health care provider should wash their hands with soap & water or use sanitizer immediately after removing gloves & other equipment and after any contact with respiratory secretions

n Personnel providing care for patients should wear disposable gloves, gowns, & eye protection to prevent conjunctival exposure

n Personnel engaged in emergency &medical units should wear a surgical mask

n At aerosol – generating activities should wear a disposable N95 respirator if available

Medication

Initiation of antiviral agent within 48 hours of symptom onset

q Tamiflue (oseltamivir)75 mg twice daily for 5 days

Relenza ( zanamivir ) 10 mg ( two 5 mg inhalations ) twice daily for 5 days

WHO guidelines for treatment

n Treating serious cases immediately

n Antiviral agents decrease risk of pneumonia & the need of hospitalization

n For risky group, including pregnant women should receive treatment as soon as possible after onset of symptoms without waiting for the result of lab

Pregnant women

n Pregnant women with confirmed , or suspected novel influenza A ( H1N1) virus should receive antiviral infection for 5 days .

n Tamiflue is the preferred treatment

n Tamiflue & Relenza are pregnancy category C indicating that no clinical studies have been conducted to assess the safety of these medications

n Fetal risk revealed in studies in animals

n Drugs should be used if the potential benefits justifies the potential risk to the embryo or fetus

n No adverse effects reported among women who received the drug during pregnancy or among infants born to these women

Chemoprophylaxis

n Prophylaxis treatment for high risk group for at least 10 days after last exposure , include :

Tamiflue 75 mg once daily

Relenza 10 mg once daily

Pre- exposure or Post exposure chemoprophylaxis is considered for :

n Close household contact

n Healthcare personnel

n Public health worker

n First responders with confirmed , or suspected 2009 H1N1

n School children at high risk for complication in close contact with a confirmed or suspected case

n individuals who is traveling to Mexico

n Antiviral should not be given for healthy children , adults or to manage outbreak in the community , school, camp, or other setting , since Tamiflue resistance have been reported

Chemoprophylaxis for Pregnant women

n A pregnant women who is in close contact with a person with confirmed, or suspected cases should receive a 10 days course of chemoprophylaxis with Tamiflue or Relanza

Vaccination

Inactivated intramuscular vaccine

q It is killed virus , some of it contain the preservative thimerosal

q Children 6m- 9 years of age should receive 2 doses separated by 3 weeks

q Children ≥ 10years and adult should receive one dose

Indication of inactivated I.M vaccination

n Pregnant women

n People who care for infants younger than 6 months old

n Health care workers

n Persons 6 month -24 years old

n Persons 25- 64 years with chronic disease

Contraindication for I.M vaccine

q Previous Guillain-Barre syndrome

q Life threatening reaction to previous influenza vaccination

Live Attenuated Influenza Vaccine (LAIV)

q It is delivered by nasal spray as a ingle dose , it does not contain thimerosal

q The groups who should receive the vaccine

Ø Persons 2- 24 years

Ø Persons 25 – 49 year live or care for infant younger than 6 months

Ø Person 25-40 years of health care worker

Contraindication for LAIV

q Sever allergy to eggs or other vaccine ingredients

q immunosuppression

q Age ≤ 2 years or ≥ 50 years

q Chronic medical condition

q Children < 5 years with asthma

q Children & adolescent on long term aspirin

Vaccination of pregnant women

q Pregnant women are at a higher priority for vaccination against both 2009 H1N1& seasonal influenza

q The vaccine considered safe in pregnancy

q The vaccine elicits antibody that persists in the infant during the 1^st 6 months

Dr. WISSAM HUSSEIN

END

Thanks Dear Dr. Wissam best regards.

_________________
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