INFLUENZAPresenter:- Dr WALIED K. BALWANModerater:- Dr Rohul Jabeen Shah

DEPARTMENT OF COMMUNITY MEDICINE, SKIMS, SRINAGAR

Difference Between Cold or FLU

A cold is a milder respiratory illness than the flu. While cold symptoms can make you feel bad for a few days. Flu symptoms can make you feel quite ill for a few days to weeks.

Cold symptoms usually begin with a sore throat, which usually goes away after a day or two. Nasal symptoms, runny nose, and congestion follow, along with a cough by the fourth and fifth days. Fever is uncommon in adults, but a slight fever is possible. Children are more likely to have a fever with a cold.

With cold symptoms, your nose teems with watery nasal secretions for the first few days. Later, these become thicker and darker.

Whether a person has typical seasonal flu or swine flu, the symptoms seem to be quite similar. Flu symptoms are usually more severe than cold symptoms and come on quickly. Symptoms of swine flu and seasonal flu include sore throat, fever, headache, muscle aches and soreness, congestion, and cough. Swine flu in particular

Influenza ,commonly known as “the flu” is an infectious disease caused by influenza virus. The word influenza comes from the italian language meaning ”influence” and refers to the cause of disease.Arachaic terms for influenza include epidemic catarrh, grippe(from the french),sweating sickness and spanish fever.

Historically Speaking •Influenza can be traced as far back as 400 BC •In Hippocrates‟ Of the Epidemics, he describes a cough outbreak that occurred in 412 BC in modern-day Turkey at the turn of the autumn season .

Early Recognized Pandemics •The first recognized pandemic occurred in July and August of 1510 when an outbreak of “gasping oppression” appeared nearly everywhere at once. It was described as a “„gasping oppression‟ with cough, fever, and a sensation of constriction of the heart and lungs”, leaving an impression strong enough for people to write of it decades later (Morens et al, 2010). At least seven contemporary and near-contemporary reports exist of the 1510 pandemic (Morens, North & Taubenberger, 2010).

Name of pandemic Date Deaths Case fatality

rateSubtype involved Pandemic Se

verity Index

1889–1890 flu pandemic

(Asiatic or Russian Flu)

1889–1890 1 million 0.15%possibly H3N8or H2N2

N/A

1918 flu pandemic

(Spanish flu)

1918–1920 20 to 100 million 2% H1N1 5

Asian Flu 1957–1958 1 to 1.5 million 0.13% H2N2 2

Hong Kong Flu

1968–1969 0.75 to 1 million <0.1% H3N2 2

Russian flu 1977–1978 no accurate count N/A H1N1 N/A

2009 flu pandemic 2009–2010 105,700-

395,600 0.03% H1N1 N/A

Problem StatementInfluenza is truly an international disease. It occurs in all countries. According to WHO “Every winter, tens of million of people get the flu. Most are only ill and out of work for a week, yet the elderly are at higher risk of death from the illness”. Its behaviour is unpredictable. It may occur in several forms. It may smoulder in a community without clinical recognition, being manifest by only serological surveys.

Attack rates tend to be high varying from 5-10% in adults and 20-30% in children. The peak of epidemic is reached in 3-4 weeks, before tending to decline.

World wide , the annual epidemics are estimated to result in about 3-5 million cases of severe illness and about 250,000 to 500,000 deaths.

AGENT/STRUCTURE

INFLUENZA VIRUS Single-stranded RNA virus Orthomyxoviridae family 3 types: A, B, C Subtypes of type A determined by

hemagglutinin and neuraminidase

Hemagglutinin (HA) and neuraminidase (NA) are the two large glycoproteins on the outside of the viral particles. HA is a lectin that mediates binding of the virus to target cells and entry of the viral genome into the target cell, while NA is involved in the release of progeny virus from infected cells, by cleaving sugars that bind the mature viral particles.

Thus, these proteins are targets for antiviral drugs. Furthermore, they are antigens to which antibodies can be raised.

Hemagglutinin & Neuraminidase

At present, three types of Influenza viruses are circulating in world; A (H1N1), A (H3N2) and B viruses. Influenza Virus Strains Type A-moderate to severe illness all age groups humans and other animals

Type B-milder disease primarily affects children humans only

Type C-rarely reported in humans no epidemics

Influenza Virus A/California/7/2009 (H1N1) Neuraminidase type Hemagglutinin type Virus type Geographic origin Strain number Year of isolation Virus subtype

12

Influenza VirusTypes A and B

Type A(Seasonal, avian, swine

influenza,….)

Type B(Seasonal influenza)

Can cause significant diseaseGenerally causes milder disease but may also cause severe disease

Infects humans and other species (e.g., birds; H5N1)

Limited to humans

Can cause epidemics and pandemics (worldwide epidemics)

Generally causes milder epidemics

Influenza Virus Nomenclature

• Influenza A viruses are classified into subtypes based on antibody responses to HA and NA. These different types of HA and NA form the basis of the H and N distinctions in, for example, H5N1. There are 16 H and 9 N subtypes known, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans.

• The most prevalent human flu viruses are H1N1 and H3N2. All of the human versions of H1N1 and H3N2 can easily transmitted from person to person because the H1 and H3 proteins recognize human cell receptors, making it easy for them to split into healthy cells.

The reservoiur

Circulating Influenza Strains and Pandemics in The 20th Century

1920 1940 1960 1980 2000

H1N1H2N2

H3N2

1918: “Spanish Flu”

1957: “Asian Flu”

1968: “Hong Kong Flu”20-40 million

deaths1-4 million deaths

1-4 million deaths

•major change, new subtype •caused by exchange of gene segments •may result in pandemic

•Example of antigenic shift •H2N2 virus circulated in 1957-1967 •H3N2 virus appeared in 1968 and completely replaced H2N2 virus

This reassortment process, known as antigenic “shift”, results in a novel subtype different from both parent viruses. As populations will have no immunity to the new subtype, and as no existing vaccines can confer protection, antigenic shift has historically resulted in highly lethal pandemics..Conditions favorable for the emergence of antigenic shift have long been thought to involve humans living in close proximity to domestic poultry and pigs. Because pigs are susceptible to infection with both avian and mammalian viruses, including human strains, they can serve as a “mixing vessel” for the scrambling of genetic material from human and avian viruses, resulting in the emergence of a novel subtype.

Antigenic “Shift”

Most recover few Suffer

Most infected people recover within one to two weeks without requiring medical treatment. However, in the very young, the elderly, and those with other serious medical conditions .

INFLUENZA VIRUS INFECTIONS IN HUMANS

Seasonal influenza Pandemic influenza Zoonotic or variant influenza

SEASONAL INFLUENZA

In humans every year seasonally in winter months

Person to person spread

Mild to severe illness, even death (in high risk)

People infected multiple times throughout their lives

3 large groups labelled A, B, C

PANDEMIC INFLUENZA Due to new virus, not previously circulating

Most people not immune

Emerges, circulates and transmits among humans

Large outbreaks outside of normal flu season

Large numbers of severe or large numbers of milder infections

ZOONOTIC OR VARIANT INFLUENZA Routinely circulating in animals

Avian, swine, others

Distinct from human influenza viruses

Occasionally infect humans

By direct contact with infected animals or environments

Do not spread very far among humans

Seasonal Influenza

A public health problem each year

Usually some immunity built up from previous exposures to the same subtype

Infants and elderly most at risk

Influenza Pandemics

Appear in the human population rarely and unpredictably

Human population lacks any immunity

All age groups, including healthy young adults

Seasonal Epidemics vs. Pandemics

The new virus must be efficiently transmitted from one human to another

Prerequisites for pandemic influenza

A new influenza virus emerges to which the general population has little/no immunity

The new virus must be able to replicate in humans and cause disease

Effect of types of contact and living conditions

TRANSMISSION AEROSOL 100,000 TO 1,000,000

VIRIONS PER DROPLET

18-72 HR INCUBATION SHEDDING

Big dropletsfall on peoplesurfaces bed clothes

Clinical features

•Incubation 1 to 3 days •Present with mild cold lead to

fulminating rapidly fatal Pneumonia •Can abruptly present with head ache

malign •Can also present with abdominal pain

with type B in children •Bacteria superinfect

UNCOMPLICATED INFLUENZA

Influenza like illness fever, cough, sore throat, Rhinorrhea, headache, Myalgias, malaise but not shortness of breath.

GI illness diarrhea or vomiting esp in children but without evidence of dehydration.

Atypical symptoms, no fever in elderly and immuno-compromised.

COMPLICATED OR SEVERE INFLUENZA

Clinical or radiological signs of LRT disease eg dyspnea

CNS involvement (encephalopathy, encephalitis)

Severe dehydration Presenting secondary complications-renal

failure, septic shock, myocarditis Exacerbation of chronic underlying disease Any other presentation requiring hospital

admission for management

Complications of Flu• Most flu symptoms gradually improve over two to five days, but

it's not uncommon to feel run down for a week or more. A common complication of the flu is pneumonia, particularly in the young, elderly, or people with lung or heart problems. If you notice shortness of breath, you should let your doctor know. Another common sign of pneumonia is fever that comes back after having been gone for a day or two.

• Ear infections, • Sinus infections,

• Dehydration, and

• Worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

HIGH RISK GROUPS

•All individuals 50 years and older

• Children 6–23 months of age

• Women who are pregnant during influenza season

• Residents of long term care facilities

• Children 6 months to 18 years of age and who are receiving aspirin therapy for extended period of time

• Persons 6 months and older with any chronic illness

PREVENTION

FOR OUTBREAK AND IMMINENT PANDEMIC

Respiratory hygiene Cough Ettiquette Hand hygiene Avoid touching eyes, nose, mouth Avoid contact with sick people Use of respirators, eye protection, gloves,

gown Travel, trade restrictions, quarantine

procedures Annual influenza vaccination

Cough etiquette

Respiratory etiquette Cover nose / mouth

when coughing or sneezing

Hand washing!

Voluntary Isolation

Separation and restricted movement of ill persons with contagious disease (often in a hospital setting and Primarily individual level) Isolate severe and mild cases Location of isolation (home, hospital) depends

on several factors (severity of illness, the number of affected persons, the domestic setting)

Do not wait for lab confirmation Plan for large number of severe cases Provide medical and social care

Voluntary Quarantine

Separation and restricted movement of well persons presumed exposed Identification of contacts

Often at home, but may be designated residential facility or hospital

Applied at the individual or community level

Regular health monitoring is essential part of quarantine Self-health monitoring and reporting

Hand WashingMethod

Wet hands with clean (not hot) water Apply soap Rub hands together for at least 20 seconds Rinse with clean water Dry with disposable towel or air dry Use towel to turn off faucet

Alcohol-based Hand Rubs

Effective if hands not visibly soiled

More costly than soap & waterMethod

Apply appropriate (3ml) amount to palms

Rub hands together, covering all surfaces until dry

Patients Cared for at Home

Potential for transmission

Must educate family caregivers

Fever / symptom monitoring

Infection control measures Hand washing Use of available material as mask …

Isolation Precautions

Source: Rosie Sokas, MD MOH UIL at Chicago

Droplet precautions: Surgical Masks

N-95 Filtering Masks

Antivirals- Oseltamivir Treatment is 75 mg twice a day for 5 days. Prophylaxis is 75 mg once a day for 7 days after last

exposure. Prophylaxis:

High risk exposure (household contacts) Moderate risk (unprotected very close exposure to sick

animals; HCW with unprotected exposure to patients) Low risk exposure: no need for prophylaxis unless

activation of exceptional measures.

Importance of the Early Treatment

INFLUENZA VACCINE

INACTIVATED INFLUENZA VACCINE RECOMMENDATIONS

Annual influenza vaccination for all persons 6 months of age and older

Protection of persons at higher risk for complications should be a focus of vaccination efforts

SPECIAL FOCUS OF VACCINATION EFFORTS

Children 6M-4Y of age Persons 50y or above Persons with chronic illnesses Immuno-suppressed ( by medication or HIV ) Women who are or will be pregnant Children 6M-18Y and receiving aspirin Residents of nursing homes and chronic care facilities Morbidly obese Health care personnel Household contacts and caregivers of children <5y

and adults >50y