Presentation on theme: "H1N pandemic What you need to Know"— Presentation transcript:
1H1N1 2009 pandemic What you need to Know Ali Hassoun, MDAlabama Infectious Diseases CenterHuntsville, ALPeople seem to have a lot of questions about the novel strain of H1N1 influenza that was first detected in Mexico in March So, I’ve developed this talk as a series of questions based on the issues that often arise during discussions on the topic.
2What is ‘the flu’? An illness caused by influenza virus A sudden onset respiratory illness with feverAffects nose, throat, air passages, and lungYearly epidemicsOccurs worldwide causing significant illness
3How are viruses different from other germs? Much smaller than animal cells or bacteriaViruses need to get a life!Need to be inside our cells to liveOur cells become virus factoriesInfluenza virus kills cells in breathing passagesTypically, viruses are much smaller than most infectious agents. Viruses generally can’t be visualized at all with ordinary light microscopes. How many times has your teenager told you to, “Get a Life!” Well now it’s my time to say it about viruses…viruses need to get a life, literally! They are unable to carry out independent metabolism. Most living things including bacteria, reproduce by cell division but not viruses! They don’t divide in order to reproduce. In fact they can only reproduce once they are inside living host cells. We have all heard about all the research on nanotechnology. One of the goals of nanotechnology is to create submicroscopic machines. Viruses are a model and testament to Nature’s nanotechnology skills. They are essentially little “machines” that go about producing more little machines. Essentially, viruses turn host cells into virus factories. Once a virus is inside a cell it goes about creating lots and lots of viral parts. Once they are made the parts self-assemble into mature virus particles. These mature copies of the original virus are then released and are free to infect other cells. What are the potential outcomes? Productive viral infections can cause cell death. The body’s immune response can eliminate the virus. Some viruses (e.g. herpes) can persist inside certain cells for life, although this is not the case for influenza virus. In influenza, destruction of cells lining the respiratory tract and the related inflammation are responsible for the disease symptoms.
4What does an influenza virus look like? Hemagglutinin proteinAllows virus to stick to cells of some animals and not othersNeuraminidase proteinHelps release new virus from cellsGenes (RNP) divided into 8 partsAllows 2 or more viruses to mix and match genesFig.1 Electron micrographIn the upper left is a picture from and electron microscope of an influenza virus. You’ll notice the projections from the edge of the virus. These represent the neuraminidase and hemagglutinin proteins on the viral surface. There are three things I want you to remember from this slide. First, the hemagglutinin protein represented as yellow spikes in the schematic picture allows influenza virus to stick to cells by binding to a specific receptor. Second, the neuraminidase protein helps newly formed viral particles get released from the cell surface so that they have the potential to infect other cells. Third, the genetic material of the influenza virus (RNP= ribonucleoprotein; complex of protein and RNA) is divided amongst 8 separate segments as shown by the orange coils in the picture. Many infectious agents have their genetic material arranged in a single ribbon or circle. However, imagine what might happen if two different influenza viruses infected the same cell. The resultant self-assembling progeny viruses might contain some genetic material from each virus resulting in a hybrid virus. This has importance later when we talk about the occurrence of pandemics.Fig.2 Schematic of influenza virus
5Why are the numbered “H” and “N” important? Used to subtype influenza A strains16 different H’s9 different N’sCurrent human subtypesA(H1N1) and A(H3N2) primarilyAntibodies against H’s and N’smade by our immune systemprotect usH and N subtypes are basis for flu vaccinesH1N1The numbered H and N designations are used to describe various subtypes of influenza A but not B or C. There are 16 different hemagglutinins and 9 different neuraminidase subtypes. Thus there are very many possible combinations. Even within the same hemagglutinin or neuraminidase subtypes there are variations due to mutations. So, the H1N1 virus that circulated in a previous year might not be the same as H1N1 subtypes in subsequent years. It turns out that our immune systems make antibodies against H and N components (AKA antigens) of influenza virus when we become infected. Moreover, these antibodies protect us from getting reinfected by the same virus. So, various H and N viral components are included in flu vaccines. These components induce the immune system to make protective antibodies without the requirement of suffering through an actual bout of the flu. Unfortunately, there are slight changes in the H and N components of circulating influenza viruses in the the community each flu season. The antibodies from a previous infection or vaccination may not be able to recognize these changed viruses as well, and we may only have some partial protection. That is why we have to get a new flu vaccine each year. Although the swine flu strain that is circulating has the same H and N type as one of the current seasonal influenza strains, it differs significantly from it.
6How is influenza spread? Patients with pandemic H1N1 influenza A virus infection are likely to be contagious from one day prior to the development of signs and symptoms until resolution of fever.Incubation– Typically 2 daysRange 1 to 4 daysViral sheddingCan begin 1 day before the onset of symptomsPeak shedding first 3 days of illnessCorrelates with feverSubsides usually by 7 daysCan be 10+ days in childrenThe usual incubation period between the time someone is exposed and infected with influenza virus to the time that they experience symptoms of illness is about 2 days. Unfortunately, viral shedding can actually begin up to a day before the onset of symptoms. Peak shedding of virus generally occurs during the first 3 days of illness and correlates with the presence of fever. The amount of virus shed influences how infectious a sick individual is to those around him/her. In other words, it determines transmissibility. The viral shedding is influenced by the host immune system and the particular strain of virus. That is why I chose to show the multiplicative domino effect image. The transmissibility has a great deal to do with the occurrence of epidemics and pandemics.
7Is flu only spread through the air? Large droplet mostlyGenerated by coughing, sneezing, talking“spitting distance”Contact with contaminated hands or surfaces, sometimesMicroscopic droplets less commonCertain other bodily fluids (eg, diarrheal stool) should also be considered potentially infectiousThere is not a lot of detailed experimental data to tease out the answer to this question. However, there is evidence that influenza can spread by contact with virus on surfaces as well as through the air. Droplet spread refers to large droplets expelled by coughing, sneezing or talking as shown in the picture. These particles generally settle out of the air within 3 to 6 feet from their origin…generally within “spitting distance.” This is felt to be the most common means by which influenza spreads. So most people who catch influenza get it from an infected person within “spitting distance.” Droplet nuclei are much smaller microscopic droplets that stay suspended in the air for a much longer time and can travel on air currents for longer distances infecting people beyond “spitting distance.” Tuberculosis commonly spreads this way, but this is a less important means by which influenza spreads compared to large droplet spread.
8the consequences of yearly epidemics in U.S.A? > 36,000 die and 200,000 are hospitalized5 to 20% of general population infectedNursing home attack rates of up to 60%85% of flu-related deaths in ages > 65Over $10 billion lostOn average, in the United States, there are 36,000 deaths and 200,000 hospitalizations every year due to influenza and its related complications. Each flu season a range of 5 to 20% of the general population comes down with the flu. Nursing home attack rates can be quite a bit higher, e.g., up to 60%. Over 85% of influenza deaths occur in people over age 65. It is estimated that influenza costs more than $10 billion in lost productivity and direct medical costs every year.
9What about past flu pandemics? Credit: US National Museum of Health and Medicine1918: “Spanish Flu”1957: “Asian Flu”1968: “Hong Kong Flu”As you can see, the Spanish Flu in 1918 was the most severe of the three pandemics resulting in 20 to 40 million deaths worldwide and 675,000 U.S. deaths. The Asian Flu pandemic resulted in double the usual number of flu season deaths in the US. The Hong Kong Flu pandemic was relatively mild by comparison.Slide images and figures from online slide set of Barbara Wallace, New York State Department of Health Interestingly, the little girl in the picture is gargling, which was a commonly advocated defense against the flu during that period of time.A(H1N1)A(H2N2)A(H3N2)20-40 m deaths675,000 US deaths1-4 m deaths70,000 US deaths1-4 m deaths34,000 US deaths
10H1N pandemicIn March and April 2009, an outbreak of respiratory illnesses was first noted in Mexico, which was eventually identified as being related to H1N1 influenza A. The outbreak spread rapidly to the United States, Canada, and throughout the world as a result of airline travelAs of July 31, 2009, over 162,000 laboratory-confirmed cases had been reported in over 160 countriesIn the United States, as of July 24, 2009, over 43,000 confirmed cases had been reported from 55 states and territories.In Alabama as of August 19, 1587 confirmed cases and madison county had 115 cases
11Novel H1N1 Confirmed and Probable Case Rate in the United States, By Age Group
12What are symptoms of H1N1 flu? Fever, usually > 101oF, and chillsSore throatNasal congestion and runny noseHeadacheBody and muscle achesDry coughTiredness and weaknessNausea, vomiting, diarrhea. gastrointestinal manifestations appear to be more common
13Who is at risk for severe infection with H1N1 virus? the most common risk factors for influenza complicationsChronic lung disease (asthma or chronic obstructive pulmonary disease)Immunosuppressive conditionsCardiac diseasePregnancyDiabetes mellitusObesity
14How is H1N1 influenza treated? Treatment is mostly supportive with rest, fluids, cough medicine, and antipyretics such as Tylenol. Aspirin should be avoided.It can be treated with antivirals. Mainly for at risk population and hospitalized patients with more than mild symptoms.Oseltamivir (Tamiflu)–capsules and oral liquidZanamivir (Relenza)–Inhaled powder
15Will a regular flu vaccine protect me? No protection from current flu vaccineH1N1 vaccine will be available mid October, initially will be indicated:Pregnant women,People who live with and care for children younger than 6 months of age,Healthcare and emergency medical services personnel,People between the ages of 6 months and 24 yearsPeople ages 25–64 years of age who have chronic health conditions (such as asthma, heart disease, or diabetes) or compromised immune systems.
16When should I call my healthcare provider? Call if you get concerned about your symptoms especially if you or a family member are high risk.If you have a fever and two or more other flu symptoms especially if symptoms are severeYour provider may recommend tests or treatment with antiviralsIf unable to drink fluids, have dark urine, or feel dizzy when standing (signs of dehydration)If you have a fever for more than 3 to 5 days even if you have already been treatedIf you start to recover from the flu symptoms and you get fever again.
17When to Seek Emergency Medical Care has difficulty breathing or chest painhas purple or blue discoloration of the lipsis vomiting and unable to keep liquids downhas signs of dehydration such as dizziness when standing, absence of urination, or in infants, a lack of tears when they cryhas seizures (for example, uncontrolled convulsions)is less responsive than normal or becomes confused
18What should I do if I’m exposed to someone with H1N1 influenza? Anti-viral prophylaxis is recommended for certain groups of people.Household close contacts who are at high-risk of complications of a confirmed or probable caseYour healthcare provider can tell you if you need preventative medicationIf you are not in a high-risk group you should:Limit your contact with others in the communityStay home at the earliest sign of flu symptomsFor updates see:A confirmed case of S-OIV infection is defined as a person with an acute febrile respiratory illness with laboratory confirmed S-OIV infection at CDC by one or more of the following tests:real-time RT-PCRviral cultureA probable case of S-OIV infection is defined as a person with an acute febrile respiratory illness who is positive for influenza A, but negative for H1 and H3 by influenza RT-PCRA suspected case of S-OIV infection is defined as a person with acute febrile respiratory illness with onsetwithin 7 days of close contact with a person who is a confirmed case of S-OIV infection, orwithin 7 days of travel to community either within the United States or internationally where there are one or more confirmed cases of S-OIV infection, orresides in a community where there are one or more confirmed cases of S-OIV infection.Infectious period for a confirmed case of swine influenza A (H1N1) virus infection is defined as 1 day prior to the case’s illness onset to 7 days after onset.Close contact is defined as: within about 6 feet of an ill person who is a confirmed or suspected case of swine-origin influenza A (H1N1) virus infection during the case’s infectious period.Acute respiratory illness is defined as recent onset of at least two of the following: rhinorrhea or nasal congestion, sore throat, cough (with or without fever or feverishness)For updates see:
19What should People with novel H1N1 flu do ? Check with their health care provider about whether they should take antiviral medicationsKeep away from others as much as possible. Do not go to work or school while illStay home for at least 24 hours after fever is gone, except to seek medical care or for other necessities. (Fever should be gone without the use of a fever-reducing medicine.)Drink clear fluids (such as water, broth, sports drinks, electrolyte beverages for infants) to keep from being dehydratedCover coughs and sneezes. Clean hands with soap and water or an alcohol-based hand rub often and especially after using tissues and after coughing or sneezing into handsWear a facemask – if available and tolerable – when sharing common spaces with other household members to help prevent spreading the virus to others.be watchful for emergency warning signs that might indicate you need to seek medical attention.
20Placement of the sick person Keep the sick person in a room separate from the common areas of the house. Keep the sickroom door closed.Unless necessary for medical care or other necessities, people who are sick with an influenza-like-illness should stay home and keep away from others as much as possibleIf possible, sick persons should use a separate bathroom. This bathroom should be cleaned daily with household disinfectant.
21Protect other persons in the home The sick person should not have visitors other than caregivers.If possible, have only one adult in the home take care of the sick person.If you are in a high risk group for complications from influenza, you should attempt to avoid close contact (within 6 feet) with household members who are sick with influenza.Avoid having sick family members care for infants and other groups at high risk for complications of influenza.All persons in the household should clean their hands frequently, including after every contact with the sick person or the person’s room or bathroom.Use paper towels for drying hands after hand washing or dedicate cloth towels to each person in the household. For example, have different colored towels for each person.If possible, consideration should be given to maintaining good ventilation in shared household areas (e.g., keeping windows open in restrooms, kitchen, bathroom, etc.).Antiviral medications can be used to prevent the flu, so check with your health care provider to see if some persons in the home should use antiviral medications.
22What about masks in a pandemic? Masks outside a healthcare setting can be considered in some circumstances.Facemasks considered for crowded settings (avoid if possible and minimize time)Protect wearer from others’ cough and protect others from wearer’s coughSingle useRespirators (N95) considered when close contact with infected person is unavoidableCare of sick person at homeRequires fit-testing to be effectiveSee the following document for details:
23What about household cleaning, laundry, and waste disposal? Throw away tissues and other disposable items used by sick person in the trash (wash hands)Keep surfaces clean by wiping down with a household disinfectant according to labelEating utensils and dishes of sick personDo not need to be cleaned separately; wash thoroughly in dishwasher or with soap and waterLinens and towelsHousehold laundry soap and tumble dry on hotAvoid “hugging” laundry prior to washing to prevent contaminating yourselfClean hands with soap and water or alcohol-based hand rub right after handling dirty laundryThe EPA has a list of disinfectants that are approved to kill influenza A: