Epidemiology Unit 4 – Flashcards

even though ischemic heart disease and stroke are the two leading causes of disease in terms of the percent and the total number of deaths caused, if you add up in totum of infectious conditions, you see that lower respiratory infections, diarrheal disease, HIV/AIDS, tuberculosis, neonatal infections, and malaria account for a large proportion of global mortality.

"diarrheal disease which accounts for over four million annual cases and The African region, by far, shares a very large burden along with the southeastern Asian region and the Western Pacific. In terms of malaria, once again, the African region shares by far the most disproportionate burden of disease with the malaria incidence being almost 10 times that of the next closest region of Southeast Asia. And so infectious disease still plays a very important role in the overall disease burden around the world. "

"And looking at, in particular, a susceptible population, that is children. Again, infectious disease place a very important role in childhood mortality. So if you look at neonatal deaths, 37% of all child mortality is in neonates under 28 days of age. The majority of those deaths are due to, in many cases, infection. So diarrheal disease and neonatal cause a substantial amount of mortality in this particular population, in this particular age group especially. "

the number of deaths from lower respiratory infections disproportionately affects children the age of four and followed by the elderly over the age of 60.

"Tuberculosis, again, disproportionately in Africa, especially sub-Saharan Africa and West Africa. That effect and also the concurrency of the TB epidemic with the HIV epidemic, again, plays a very important role in the infectious disease burden in these countries. And then, finally, what we call the neglected tropical diseases, leishmaniasis, helminthic disease, schistosomiasis, among others. Hookworm, again, account for a substantial disease burden, again, primarily, in several regions of the world-- Africa, South America, and Asi"

We expect to see a decrease based upon current models and estimates of-- for example-- malaria, tuberculosis, HIV/AIDS, acute respiratory infections. The trade-off, of course, is the increase projected for the diseases of lifestyle such as chronic conditions as heart disease, cancer, stroke, and others. And again, similar patterns for four different diseases-- HIV, tuberculosis, COPD or Chronic Obstructive Pulmonary Disease, and diarrheal disease. For the most part, the models project fairly good news. For example, a major decline in diarrheal disease-- and this is up through the year 2020-- a gradual decline in HIV, even under the worst case assumption. A decline in tuberculosis, but under the worst case assumption there would be a slight increase. But especially for chronic obstructive pulmonary disease. And this is primarily a function of increased smoking prevalence in certain countries around the world. So we can expect to see, in some cases, epidemic levels of chronic pulmonary disease as a function of the increased rates of smoking in selected countries around the world.

Sanitation.

effect of moving from an infectious disease burden to chronic disease burden, and this term is called the transition or the epidemiologic transition, which has already occurred in most high income and most developed countries as we've moved from the primary burden due to infectious conditions two more chronic conditions such as heart disease, cancer, and stroke.

the critical feature here has been just improved sanitation, improved housing, safer food, safer water, safer air. Just better living conditions has led to this transition from infectious conditions to diseases of lifestyle, of longevity, that is, more chronic conditions such as heart disease, cancer, and stroke.

"New"" diseases: Novel H1N1 flu,"bird flu," SARS, HIV/AIDS, BSE, Hantavirus, Cyclospora, Cryptosporidia New geographic ranges: Malaria in travelers, West Nile virus, Chagas disease New populations at risk: Listeria in pregnant females, giardiasis in day care workers, anthrax in postal workers"

Mumps Whooping cough (pertussis) Salmonella Novel H1N1 influenza Cryptococcus gatti Drug-resistant bacteria (TB, etc.) Lyme borreliosis West Nile virus E. coli O157H7 Cryptosporidiosis Hantavirus Measles

Dengue fever Q fever (Coxiella burnetti) Novel H1N1 and avian influenza Japanese B encephalitis West Nile virus SARS coronavirus Vibrio cholera Yellow fever Nipah paramyxovirus Chikungunya virus Ebola virus

""Emerging" Infectious Diseases: Factors Influencing "Emergence" Population growth/zoonotic interface Change in underlying health of community (concomitant infection, starvation, etc.) Speed of travel Geographic alterations (homes, dams, forests, etc.) Climate changes War and social disruption Changing living patterns Medical advances "

"Incidence: number of new cases of disease or health condition in a population Prevalence: number of persons effected by disease or health condition at point or period of time Attack rate: number of cases of disease or health condition in those exposed to a risk factor Secondary attack rate: number of cases of disease or health condition in those exposed to ""initial cases"""

The attack rate is simply the proportion of cases that are created after exposure to a primary case. So it's the number of secondary cases divided by the number of exposed population minus the primary cases. And so the issue is here, what is the secondary attack rate? And what factors influence the secondary attack rate? We start off with describing or defining what the reproductive number is. The reproduction number, or r sub 0, is simply the average number of secondary cases created by an infectious host when exposed to a population that is susceptible, that is, probably a less than ideal immune status, that is, that has not received immunization or natural immunity. So for example, the reproductive number for measles ranged between 12 to 18 secondary cases. That means that one primary case can produce between 12 and 18 secondary cases, indicative of a very contagious, infectious disease. The reproductive number for smallpox range between five and seven. Still fairly contagious, although nowhere near as infectious as measles. However, in most populations, a proportion of the population is immune or not susceptible. And so we also have to look at the so-called mixed community. And this is the function of r, which is the average number of secondary cases in a so-called mixed community comprised of people who are both immune and those who are susceptible. And so a secondary attack rate is the ability of a primary case to induce or create secondary cases following exposure to the primary case. The reproductive number, or r sub 0, is actually able to quantify the potential for disease transmission by measuring the number of secondary cases that a primary case can result in. And so the basic reproductive number, which is r sub 0, is the mean number of individuals who are directly infected by a primary infectious case during the infectious period when introduced into a totally susceptible population. "

And so the mathematical formula for the reproductive number r sub 0 deals with the probability of transmission per contact times the number of contacts per unit time times how long the person is infectious. And the key thing about this is if the reproductive number r falls below one, then the possibility of disease eradication exists. And so far, the only disease we've eradicated in humans is smallpox. And this was because we were able to drive the reproductive number down below one through very high vaccine coverage levels.

If the reproductive number r is equal to one, then the disease would become endemic in a population. That is, will exist on a consistent low level in a community or population. And if the reproductive number r is above one, then the chance for outbreaks or epidemics increases.

So r sub 0 is actually a very useful summary number in terms of the infectivity, or the ability to create secondary cases, of an agent is. The definition, again, is the average number of secondary cases that a typically infectious person will cause in a completely susceptible population. Remember there are two kinds of populations. There's the population which everybody is susceptible, has no immunity, or more commonly, the mixed population, which is comprised of people who are susceptible and those who are immune. And the r sub 0-- that is, the population which is susceptible-- the r sub 0 is a good measure of the potential for an infectious agent to spread through a population. So it's a way of quantifying the potential for disease transmission in a population which is susceptible.

"So what factors play a role in determining the quantity, or the level, of the reproductive number, or r sub 0? Again, this refers to a susceptible population. I mentioned the formula is that r sub 0 is equal to p times c times d, where p is the transmission probability for every exposure. And again, this depends on the route of exposure. And so, for example, the probability of transmission of the HIV virus through a handshake is close to zero, in fact is zero. The probability of transferring or transmitting the HIV virus through a transfusion is almost 100%, so the level would be one. And the probability through sexual intercourse, depending upon the type of intercourse, is on the order of about 1 per 1,000 to 1 per 100. We can basically introduce interventions that are designed to lower the level of probability of transmission. So, for example, barriers like condoms, like using gloves, for example, if you're a health care worker, and screening blood before it's sold or administered for transfusion are ways to lower the probability of transmission per exposure. The second feature in this model is the number of contacts per unit time. And so, for example, the more contacts the person may have, the greater the chance of disease transmission. So for example, in a disease that's spread through airborne transmission, for example, or droplet transmission, the closer the population, the greater the chance of contacts, the greater the chance of disease transmission. So again, an intervention in this case would be social isolation or quarantine, separating the population so they would not be susceptible to crowding, and as a result, less of a chance of coming into contact with an infectious agent or with a disease carrier. The third factor of this model is the duration of how long the person is infectious. And so again, the longer the person is infectious, the greater the chance of disease transmission. And so there are medical interventions that can reduce this duration period, thereby reducing the level of the r sub 0, or the reproductive rate. By, for example, intervening in the probability of transmission, intervening in the number of contacts per unit time through barriers or isolation, or through reducing the duration of being infectious, all can limit the reproductive number. Another feature about the reproductive number is it tells you what proportion of the population would have to be covered by a vaccine in order to introduce herd immunity into a community or into a population. Herd immunity essentially is the fact that a certain proportion of the population is protected because the preponderance of the population is immune, either through natural immunity or through vaccination. And the remaining population that would be susceptible is protected because of the function of herd immunity would protect that small remaining population. And again, this is a function of the reproductive number. The more infectious or the more contagious an agent is, the higher the level of vaccine coverage is required to impart effective herd immunity. For example, the formula for that would be that r is equal to r sub 0 minus the product of the proportion of transmission times the reproductive number. And r in this case is the mixed population. r sub 0 is the susceptible population. And so if you go through and solve for r sub 0-- if it becomes two, for example-- then r would be less than one, and the proportion of the population required to have herd immunity would be about 50%. If the disease, however, is more infectious or contagious-- let's say that the reproductive number is four, that is, one primary case could create four secondary cases-- then the reproductive number would be less than one if the proportion of immune people in the population is equal or greater than 75%. So the greater the reproductive number, the higher the level of vaccine coverage or immunity in the population would be required to have true herd immunity"

"Measles has a reproductive number on the order of 12 to 18. Let's say 15 on the average. So with a reproductive number of 15, how large would you have to have in terms of vaccine coverage in the population to impart true herd immunity? Well, solving for this, you have the mathematical model here basically results in a figure of 94%. And so in order to have herd immunity against a measles outbreak would require that 94% of the population be immune, either through vaccination or through natural immunity. So that is because the reproductive rate for measles is so high. "

"There are three major factors here that affect this. The first is the level of susceptibility in the population, how susceptible or how the level of the population that is not immune, that has no prior immunity to the infection. The greater the susceptibility, the greater the chance of a secondary case occurring in the population. The second point would be the level of social interaction between individuals. That is, crowding would play a very important role, especially in person to person transmission. And the third factor would be the extent of interaction between those who are ill and infectious and those who are susceptible. And so those three factors play a very important role in the level of the secondary attack rate. "

The secondary attack rate can vary widely even for the same agent or same disease process. For example, in the pandemic of influenza H1N1 subtype in 2010, 2011, the reproductive rate varied from 1.5 in Mexico to 2.7 in New York City, a function of some of these factors. Crowding, interaction, and population susceptibility all affected the level of reproductive rate.

Reproduction Number (R0) Average number of "secondary" cases produced by an infectious host when exposed to a susceptible population Examples: Measles R0 = 12-18 Smallpox R0 = 5-7 However, not everyone susceptible R = Average number of "secondary" cases in "mixed" community

Reproductive Number, R0 A measure of the potential for transmission The basic reproductive number, R0 The mean number of individuals directly infected by an infectious case through the total infectious period when introduced to a susceptible population If R 1, then infection will become epidemic.

"R0 Summary Useful summary statistic Definition: the average number of secondary cases a typical infectious individual will cause in a completely susceptible population Measure of the intrinsic potential for an infectious agent to spread

"R0=p×c×d p, transmission probability per exposure: depends on the infection HIV: p (handshake) = 0, p (transfusion) = 1, p (sex) = 0.001 Interventions often aim at reducing p Use of condoms, gloves, screening of blood c, number of contacts per time unit: relevant contact depends on infection Same room, within sneezing distance, skin contact Interventions often aim at reducing c Isolation, sexual abstinence d, duration of infectious period May be reduced by medical interventions "

Herd immunity: A proportion of the population is protected because the majority of the population is immune (naturally or through vaccination).

"Herd Immunity If R0 is the mean number of secondary cases in a susceptible population, then R is the mean number of secondary cases in a population where a proportion, p, are immune. R=R0−(p×R0) What proportion needs to be immune to prevent epidemics? If R0 is 2, then R 0.50. If R0 is 4, then R 0.75. The higher R0, the higher proportion of immune required for herd immunity. Measles: If R0 =15, how large will p need to be to avoid an epidemic? p>1−115=0.94"

"What Can Influence the Secondary Attack Rate? Level of susceptibility in the population Level of social interaction amongst susceptibles Interaction of those ill and those susceptible Result: Widely varying R levels for same disease process

"Antigens An antigen is any substance that causes your immune system to produce antibodies against it. It may be a foreign substance from the environment such as chemicals, bacteria, viruses, or pollen. It may also be formed within the body, as with bacterial toxins, called endotoxins.

"Antibody An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Antibodies are also produced when the immune system mistakenly considers healthy tissue a harmful substance."

"Immunoglobulin M (lgM) Immunoglobulin M, or lgM, is a basic antibody that is produced by B cells. It is the primary antibody against A and B antigens on red blood cells. IgM is by far the physically largest antibody in the human circulatory system. It is the first antibody to appear in response to initial exposure to an antigen.

"Immunoglobulin G (lgG) Immunoglobulin G (lgG) are antibody molecules. lgG antibodies are predominantly involved in the secondary immune response. (The main antibody involved in primary response is lgM.)

"Definitions Used in ID Epidemiology Incubation period: extends from the time a person is infected until he/she develops symptoms of the disease (usually expressed as an interval or a mean; the length is determined by the infectious dose of the agent) Generation time: the mean time interval between infection of one person and infection of the people that individual infects Infectious period: the time period during which a person can transmit a disease Latent period: the time period from infection until the infectious period starts Knowledge of these time periods for different diseases is an important diagnostic aid and also allows an estimate of the time when exposure occurred.

"Hours Days Months/ Years B. cereus Strep pharyngitis BSE Staph toxin Pneumococcal pneumonia Rabies Cl. perfringens N. gonorrhoeae Leprosy N. meningitidis Cl. Botulinus Influenza Salmonellosis RMSF Shigellosis Measles Varicella "

"erd Immunity Resistance a population acquires as a whole to infectious disease. The number of individuals that must be immune to prevent an epidemic outbreak of a disease is a function of: Infectivity of the disease (I) Duration of the disease (D) Proportion of susceptible individuals in the population (S) When 70% of individuals in a population are immune, the propagation from individual to individual is not sustained and epidemics do not occur. "

Infectivity: ability of agent to invade and multiply in host Pathogenicity: ability of agent to produce clinically apparent illness in host Virulence: a quantitative measure of the ability of a microorganism to cause severe disease in a host Immunogenicity: ability of agent to produce immune response in a host

LD50 (lethal dose 50%): the number of organisms needed to cause death in 50% of the infected hosts ID50 (infectious dose 50): the number of organisms needed to cause an infection in 50% of the hosts

"Chain of Infection: Necessary Events Presence of a susceptible host An infectious agent capable of causing an infection Presence of a reservoir Portal of exit from reservoir and entry into host Mode of transmission

TRUE

Virulence.

All of the above.

"Chain of infection: infectious Agent: Bacteria, Viruses, fungi, protozoa, helminths Reservoir: people, equipment, water Portals of exit: excretions, secretions, drophlets, skin Means of transmission: direct contact/fomite, injection/ingestion, airborne/aerosols Portal of entry: broken skin, mucous membrane, gastrointestinal/respiratory/urinary tracts Suspeptible host: neonates, diabetics, immunosuppressed, cardiopulmonary disease"

"Means of Transmission Contact Direct (skin or sexual contact) Indirect (infected fomite, blood, or body fluid) Droplet Common vehicle (food/waterborne) Airborne Vector-borne (mosquito, tick, snail, etc.) Perinatal (vertical) Similar to contact infection, but contact may occur: In utero during pregnancy via placental transfer During passage through birth canal In postpartum period "

"Epidemiologic Triad Disease is the result of forces within a dynamic system consisting of: Agent of infection Environment Host"

"Agent: infectivity, pathogenicity, virulence, immunogenicity, antigenic stablity, survival Host: age, sex, genotype, behavior, nutritional status, health status Environment: weather, housing, geography, occupational setting, air quality, food"

"Ecological Factors in Infections Altered environment Air conditioning Changes in food production and handling Transportation; deep-freeze; fast-food industry; intensive husbandry with antibiotic protection Climate changes Global warming Deforestation Ownership of (exotic) pets Air travel and exotic journeys/global movements Increased use of immunosuppressives/antibiotics

"Definitions Used in ID Epidemiology Infectious diseases: All diseases caused by microorganisms Communicable diseases: Diseases that can be transmitted from one infected person to another, either directly or indirectly Transmissible diseases: Diseases that can be transmitted from one person to another by "unnatural" routes

"Index: the first case identified? Primary: the case that brings the infection into a population Secondary: infected by a primary case Tertiary: infected by a secondary case"

"Microbiologic Classification of Infectious Diseases Bacterial Viral Fungal Parasitic Prion: protein in a misfolded form"

"Classification of Modes of Transmission By generation: horizontal or vertical (perinatal) By contact: direct or indirect By vehicle: vector-borne, food/water-borne, airborne, device-borne By source: point source, continuing source, person to person "

A host that carries a pathogen without injury to itself and serves as a source of infection for other host organisms (asymptomatic infective carriers)

"Classification of Infectious Agents by Reservoir Reservoir Example Human Sexually transmitted infections Animal (zoonoses) Salmonella, rabies, etc. Soil Tetanus, histoplasmosis, etc. Water Legionnaire's, Pseudomonas, etc."

A host that carries a pathogen without injury to itself and spreads the pathogen to susceptible organisms (asymptomatic carriers of pathogens)

"Pathogen Vector Viruses (arbovirus) Mosquitoes Bacteria (Yersinia) Fleas Bacteria (Borrelia) Ticks Rickettsias (R. prowazeki) Lice, ticks Protozoa (Plasmodium) Mosquitoes Protozoa (Trypanozoma) Tsetse flies Helminths (Onchocerca) Simulium flies"

"The Essential Elements for the Evolution of an Epidemic Appropriate infectious agent Salmonella Sufficient number of susceptibles Measles Mechanism that allows for rapid spread Legionellosis

"Circumstances That Increase the Likelihood of an Epidemic Change in: Dose of agent Virulence of agent Mode of transmission Susceptibility of host Cultural or behavioral aspect of host

Factors Making Person-to-Person Transmission Likely Individual Prior exposure to agent (immunity); immune status; general health status Social "Closed" community; behavioral issues; cultural patterns Environment Climate change; use of intermediate vehicle for transmission (water, food, etc.)

"Features of Infectious Agent That Make Person-to-Person Transmission Likely High infectivity of organism Measles Short generation time (as compared to incubation period) Varicella Ability of organism to exist in carrier state Hepatitis B

"Definitions Used in ID Epidemiology Carrier state: A carrier (inapparent, convalescent, chronic) is a person who harbors the pathogen and is able to transmit it but shows no clinical sign of infection

"Carriers Hosts that harbor a pathogen without clinical symptoms and are capable of transmitting the infectious agent (sometimes unknowingly) are known as inapparent carriers. Carrier state may be: Short (transient) Long term (chronic, e.g., tuberculosis, herpes, hepatitis B, typhoid) Carrier state may also occur during: Incubation period (before symptoms appear) Convalescent period (recovery)

"Types of ""Carrier"" States for Infectious Agents Inapparent: polio, meningococcus Incubatory: measles, chicken pox Convalescent: salmonella, diptheria Chronic: typhoid, HIV, hepatitis B

"Impact of Influenza A significant cause of morbidity and mortality, especially in high-risk persons who develop serious complications (up to 90 million cases per year in the United States) Annual economic costs in the United States: 69 million work days 315 million days restricted activity $12 billion health care burden

Influenza and Pneumonia 88,363

"Influenza: A Historical Perspective First reported in epidemic form by Hippocrates in 412 BC Term ""influenza"" introduced in 15th century First recorded pandemic, 1580 Largest pandemic 1918-1919; at least 25 million deaths First viral strain recovered from a human, 1933

"1918-1919 Pandemic The worst natural calamity of the 20th century with an estimated global loss of 40 to 100 million lives. The highest death rates were seen in adults aged 15 to 34 years. Fourteen million people were killed in World War I; more than 40 million died from the flu epidemic in the following years. Re-creation of an influenza virus with the eight genome segments of the 1918-1919 strain revealed: It produced 39,000 times more virus particles in the lungs of mice than more contemporary H1N1 strains. It replicated in the absence of a host-produced protease.

"The Virulence of the 1918 Flu The effect of the 1918 influenza epidemic was so severe that the average life span in the United States was depressed by 10 years. The influenza virus had a profound virulence, with a mortality rate at 2.5% compared to the previous influenza epidemics (>0.1%). The death rate of influenza and pneumonia for 15- to 34-year-olds was 20 times higher in 1918 than in previous years. Physicians reported that patients with seemingly ordinary influenza would rapidly ""develop the most viscous type of pneumonia that has ever been seen,"" and later when cyanosis appeared in the patients, ""it is simply a struggle for air until they suffocate."" (Grist, 1979) Other reports note that the influenza patients ""died struggling to clear their airways of a blood-tinged froth that sometimes gushed from their nose and mouth."" (Starr, 1976) Patients literally ""died on the street.""

"The Next Threat of Pandemic Influenza In 1976, the United States experienced a swine flu scare. When a new flu virus was first identified at Fort Dix, New Jersey, it was labelled the ""killer flu,"" and health experts were afraid that it would infect people around the world. In fact, swine flu never left the Fort Dix area. Research on the virus later showed that if it had spread, it would probably have been much less deadly than the Spanish flu. "

Major Strains and Subtypes Human strains: A, B, and C Subtypes classed by surfaced proteins Hemagluttinin Neuraminadase Surface protein variants common in humans (and featured in nomenclature): Hemagluttin: H0, H1, H2, H3 Neurmaminadase: N1, N2 Presently recognized are 16 HA and 9 NA antigenic types. Virtually all combinations of HA and NA exist in nature. Most combinations result in mildly pathogenic viruses, but some can be highly pathogenic.

"Epidemiologic Features Attack rate may exceed 20-40%. Peak of epidemic within 4 weeks of introduction of virus. Highest incidence usually seen in 5- to 14-year-olds. Gender and race have little effect on incidence, but age does.

"Influenza Changes Antigenic drift: Minor change in influenza subtype Resulting usually from RNA point mutation in coding region of hemagglutinin Antigenic shift: Major change in subtype Occurs with recombination of RNA genome segment

"Influenza Type A Antigenic Shifts Year Subtype Severity of Pandemic 1889 H3N2 Moderate 1918 H1N1 Severe 1957 H2N2 Severe 1968 H3N2 Moderate 1977 H1N1 Mild 2009 H1N1 Moderate"

"Clinical Manifestations Short incubation period Abrupt illness onset Initial symptoms: Headache, chills, dry cough Later symptoms: High fever, myalgia, malaise, and anorexia

"Vaccine Coverage and Vaccine Efficacy Vaccine coverage: Proportion of population that has been immunized Nvaccinated divided by Nvaccinated + Nunvaccinated Vaccine efficacy: Measure of how effective a vaccine is in a population ARunvaccinated − ARvaccinated divided by ARunvaccinated "

"Calculation of Vaccine Efficacy in an Outbreak Setting % Efficacy = 100 × Attack Rate in Unvaccinated − Attack Rate in Vaccinated Attack Rate in Unvaccinated Example: Measles at Lackland Air Force Base 43 cases of measles in new recruits 29 of these in unvaccinated (386 total unvaccinated) 13 of these in vaccinated (2,038 total) 100 × 29/386 − 13/2038 divided 29/386 = 0.075 − 0.0063 divided 0.075 = 0.914 = VE of 91.4% "

"Influenza Vaccine Vaccinating persons at high risk is the most effective measure of reducing impact. Prevents illness in approximately 70-90% of healthy individuals Protection develops approximately 2 weeks after vaccination. Effectiveness depends on: Degree of similarity between circulating virus and that used in vaccine Age and immunocompetence of vaccine recipient

"Inactivated Influenza Vaccine Efficacy 70-90% effective among healthy persons 30-40% effective among frail elderly persons 50-60% effective in preventing hospitalization 80% effective in preventing death"

2012-2013 Influenza Vaccines 1. Trivalent inactivated vaccine (TIV) for intramuscular injection For persons aged 6 months and older Five manufacturers (differences in recommended age groups) 2. Live attenuated influenza virus vaccine (LAIV) for intranasal administration Healthy nonpregnant persons aged 2-49 years One manufacturer 3. Intradermally administered trivalent inactivated vaccine Persons aged 18-64 years One manufacturer 4. High-dose trivalent inactivated vaccine for intramuscular injection Persons aged 65 years and older One manufacturer

"Who Should Receive Seasonal Flu Vaccine? All persons >6 months, and especially targeted populations: Residents of chronic care facilities Adults and children with chronic cardiopulmonary illness Adults and children with chronic metabolic, renal, or immunosuppressive disorders Children and adolescents on long-term ASA therapy Women who will be pregnant during flu season Newly recommended groups

"Who Else Should Be Especially Targeted to Receive Flu Vaccine? All persons over the age of 65 years New high-potency vaccine available All persons who can transmit influenza to those at risk Health care providers, all contacts of targeted populations All persons with HIV infection Breastfeeding mothers Travelers All children 6 months to 18 years of age All contacts of children 0-25 months

"Novel H1N1 Flu Appeared first in Mexico City, March 11, 2009 Rapidly spread to United States, then on to rest of the world In June 11, 2009, WHO raised its pandemic alert level to "Phase 6" ""Phase 6"": widespread transmission on two continents Cases have been reported in virtually all countries to date Considered novel because its genome has not been encountered before Derived from a "quadruple reassortment" of two swine, one human, and one avian strain

"H1N1 Infection in the United States Virus was transmitted between people at a rate comparable to previous pandemic strains. Infection rate greater in 0-24 year age group: Was 4-5 times greater than for 25-49 year age group Was 20 times greater than for those >65 years of age 83% of deaths and 71% of hospitalizations were in people 5-64 years old Severity: Case-fatality ratio similar to usual seasonal influenza: 0.1-0.3% of medically attended cases At greater risk: pregnant women and individuals with neurological disorders Native American groups also at higher risk for severe infections

"Prevention and Treatment for H1N1 Vaccination: Last year's vaccine was monovalent; this year will be part of standard trivalent vaccine. Current control measure: Prophylactic meds (antivirals). Current strain resistant to Amantidine. Still sensitive to neurominidase inhibitors, Olsetamivir and Zanamivir.