INFLUENZA (The Flu)What Nurses Should Know Felissa R. Lashley, RN, PhD, FAAN, FACMG Professor, College of Nursing, and Interim Director, Nursing Center for Bioterrorism and Infectious Disease Preparedness, College of Nursing Rutgers, The State University of New Jersey This module is designed to highlight important information about influenza. The influenza virus, in addition to being the cause of influenza, an important infectious disease, is also considered to be a potential agent for bioterrorism and is considered as a possible Category C bioterrorism agent by the Centers for Disease Control and Prevention (CDC). This module was supported in part by USDHHS, HRSA Grant No. T01HP01407.
Some General Points • The influenza virus is considered to have the potential for use as an agent for bioterrorism, most probably by altering it to a mutated form with greater virulence, infectivity, more efficient human-to-human transmission, and antiviral resistance. • CDC considers it to be a Category C agent under others.
Some General Points cont. • This module is arranged as follows: etiology, epidemiology, transmission, incubation period, overall clinical illness picture, clinical manifestations, clinical differentiation between the common cold and flu, complications, diagnosis, treatment, management including infection control measures and patient/staff education, and prophylaxis and vaccination. • Avian influenza is considered at the end of the content before the case studies. • Case studies, test questions and information sources appear at the end of the module.
Objectives At the conclusion of this module, the participant should be able to: • Identify the viruses that can cause influenza • Describe signs and symptoms commonly associated with influenza • Identify the major complications of influenza • Describe symptoms that can help differentiate between upper respiratory infection and influenza
Objectives cont. • Identify antiviral agents in current use for prevention of influenza • Identify antiviral agents in current use for treatment of influenza • Name the groups for whom flu vaccination is recommended • Describe what is meant by avian influenza
Etiology • Influenza viruses types A, B, & C infect humans • Influenza types A & B can cause widespread outbreaks • Influenza type A tends to be the most severe • Influenza A virus types have most potential for use as bioterrorism weapon • Influenza viruses are RNA viruses classified in Orthomyxoviridae family • Can mutate and cross species barrier such as fowl to humans
Etiology cont. • Influenza subtypes are referred to by their hemagglutinin (H) and neuraminidase subtypes (N) which are surface glycoproteins of the virus • Examples: Avian influenza virus subtypes A H5N1 and H9N2 which appeared recently in Hong Kong and other areas • Influenza viruses have the ability to develop antigenic variants through viral mutation. Persons develop antibodies to specific variants which may not confer protection against another. This helps explain why there are seasonal epidemics and provides the basis for understanding the rationale for what strains of the virus will be used each year in vaccine production.
Epidemiology • Worldwide distribution • Outbreaks usually occur suddenly • Flu spreads through communities resulting in an epidemic. Cases tend to peak after about 3 weeks and begin to subside after another 3-4 weeks
Epidemiology cont.-2 • Have been several great influenza pandemics: • 1918-19 “Spanish” flu • Caused 20-40 million deaths worldwide • A large proportion of these deaths was in healthy adults 15 to 35 years of age • 1957 “Asian” flu • 1968 “Hong Kong” flu • 1977 H1N1 influenza A virus subtype, “Russian” flu
Epidemiology cont.-3 • Peak season is November through March • Each year about 10 to 20% of Americans develop influenza • In the US, approximately 100,000 people are hospitalized with influenza each year, and about 36,000 die
Transmission • Major transmission route is through airborne large respiratory droplets with particles larger than 5 microns (μ) in diameter that are expelled from the respiratory tract of an infected person when they cough or sneeze • Direct contact with fomites (inanimate objects) contaminated with infected droplets or secretions and then touching ones nose or mouth • Transmission from infected birds, poultry or pigs (less common)
Incubation Period • 1 to 4 days with average of 2 days • Adults are infectious from day before symptoms begin through about 5 days after onset; children can be infectious for 10 or more days after onset and those who are immunosuppressed can shed virus for weeks or even months.
Overall Clinical Illness Picture • Influenza infection can run a spectrum from asymptomatic or mild illness through fulminant primary viral pneumonia • For most uncomplicated cases, influenza resolves spontaneously in a few days but cough and malaise often last 2 weeks or more • Major clinical pictures: • Rhinotracheobronchitis • Primary viral pneumonia • Respiratory viral infection followed by secondary bacterial pneumonia • There is no “stomach” flu - these manifestations are from other disorders
Major influences on clinical illness development and complications of influenza • Age - elderly (over 65 years of age) and young children particularly younger than 5 years of age and especially those 6 to 23 months are particularly vulnerable • Presence of other chronic underlying illnesses such as chronic cardiac or pulmonary disease • Compromised immune status such as from immunosuppressive drugs, or conditions such as malnutrition or pregnancy • Lack of access to health care • Crowded living conditions that facilitate transfer of respiratory pathogens that can include congregate and institutional settings especially if precautions such as respiratory hygiene dn cough ettiquette are not observed • Health care workers may be at higher riskfor transmission
Abrupt onset of constitutional and respiratory symptoms Fever, duration typically 1 to 5 days, with an average of 3 days and peak within 12 hours after symptoms. Typical temperatures are 38 to 40 deg. C. Myalgia Headache Chills Cough, usually unproductive Sore throat Malaise Rhinitis May have eye tearing, burning, photophobia or eye pain Children may have otitis media and nausea and vomiting as well as febrile convulsions in addition to other symptoms Elderly persons may present with minimal respiratory symptoms but show lassitude, high fever and confusion Respiratory symptoms may increase as fever decreases Clinical Manifestations
The following symptoms are more commonly seen in influenza rather than the common cold: High fever lasting 3 to 4 days Headache Myalgia Fatigue and weakness Extreme exhaustion Severe chest discomfort and cough The following symptoms are more commonly seen in the common cold rather than influenza: Stuffy nose is common Sneezing is common Cough is generally mild to moderate Symptoms such as fever, headache, aches and pains and exhaustion are rare in those with colds. Clinical Differentiation Between the Common Cold and the Flu(see Table 1 at end of module)
Complications may be respiratory or non-respiratory or both Major respiratory complications include: • Primary viral pneumonia • Occurs most frequently in elderly or persons with cardiopulmonary disease • Can occur in healthy immunocompetent persons or pregnant women • Usually develops rapidly, within 1 day or onset of illness • Symptoms include rapidly progressing fever, tachypnea, tachycardia, cyanosis and hypotension • Signs include bilateral crepitant rales on chest examination, chest x-rays showing nonconsolidating pulmonary infiltrates, but sometimes areas of consolidation, blood gas studies show hypoxemia, blood counts may show leukocytosis with a left shift • Mortality is high, and extensive fibrosis and interstitial inflammation may develop
Complications cont.-2 • Secondary bacterial pneumonia • Occurs most frequently in elderly or persons with pulmonary disease • Typical course of influenza illness seems to be improving but fever with shaking chills returns, pleuritic-type chest pain, productive cough with bloody or purulent sputum • Signs include local areas of lung consolidation on chest X-ray, sputum culture and Gram stain may reveal predominance of bacterial pathogen, most commonly Streptococcuspneumoniae, Staphylococcusaureus, Haemophilusinfluenzae, or Moraxellacatarrhalis • Mortality can approach 7%
Complications cont.-3 • Combined bacterial-viral pneumonia • Coinfection can yield varying symptoms which may be like primary viral pneumonia at first • Coinfection with S.aureus may carry a particularly high mortality rate • Exacerbation of chronic pulmonary disease such as asthma or in persons with cystic fibrosis
Complications cont.-4 Major non-respiratory complications include: • Cardiac complications particularly electrocardiographic abnormalities and myocarditis • Central nervous system complications such as seizures, especially in children, and acute encephalitis • Reye’s syndrome, a neurologic and metabolic disorder occuring mainly in children and adolescents from 2 to 16 years of age. It appears more closely associated with influenza B than influenza A and has a mortality rate of 10% to 40%. Not prescribing aspirin for patients, especially children and adolescents with viral infections has decreased the incidence of Reye’s syndrome. • Myositis may occur primarily in children and particularly after influenza B along with myoglobinuria and rhabdomyolysis leading to acute renal failure.
Diagnosis • Important to make diagnosis as quickly as possible • Facilitated by community surveillance knowledge about influenza outbreak patterns in the community • May be made on basis of clinical signs and symptoms along with knowledge about influenza patterns in the community. Thus in the setting of a confirmed influenza outbreak in a given community, persons who are not residents of institutions and who have muscle aches, fever and two respiratory symptoms probably have influenza according to Shorman & Moorman, (2003).
Diagnosis cont. Laboratory diagnostic methods include: • Viral culture (need expert technicians and time but excellent specificity and sensitivity), reverse transcriptase polymerase chain reaction (labor-intensive, costly but quick with excellent specificity and sensitivity), serology, rapid antigen testing, and immunofluroescence assays.
Treatment (this is not comprehensive and is not meant as recommendations) Certain antiviral agents may be used • Newer antiviral agents include zanamivir and oseltamivir (Tamiflu). Both are effective against influenza A and influenza B. These also need to be administered within the first 48 hours of symptoms. Both are category C agents in pregnancy and there is a risk for adverse effects in those with underlying respiratory disease. It is administered via oral inhalation. Oseltamivir may result in nausea and vomiting side effects so needs to be taken with food. It is administered orally. Transient neuropsychiatric events have been described in adolescents and some adults taking oseltamivir. These two agents were the only ones licensed for flu prevention and treatment in 2008.
Management including Infection Control Measures Management includes: • Symptomatic treatment such as encouraging fluids and rest; the treatment of symptoms with over-the-counter medications but not aspirin in children or adolescents • Comfort measures • Specific management approaches depend upon symptoms, complications and characteristics and condition of the individual patient
Management including Infection Control Measures cont.-2 Infection Control Measures • Appropriate prophylaxis and immunization is an important part and is discussed below • Respiratory hygiene and cough etiquette programs are now a part of standard precautions • Initiate at first point of contact with even a potentially infected person • Includes education which may be visual and\or verbal at an appropriate educational level with cultural considerations of patients and the people who accompany them • Should include informing personnel if they have any symptoms of respiratory infection, having tissues provided to patients and visitors, throw tissues away after use in proper container, instructing them to cover their mouth and nose when coughing or sneezing, providing alcohol based hand rubbing dispensers and supplies for handwashing and educating patients and staff in their use, encourage handwashing after coughing or sneezing, offering masks to persons who are coughing, encouraging coughing persons to sit at least 3 feet away from others, instruct patients and providers not to touch eyes, nose or mouth and have health care personnel observe Droplet Precautions in addition to Standard Precautions. Health care workers should use standard precautions with all patients.
Management including Infection Control Measures cont.-3 Infection Control Measures cont. • Standard Precautions are detailed in a separate module • Droplet Precautions are detailed in a separate module
Persons with respiratory infection symptoms should not visit patients Health care workers with respiratory infection symptoms should be excluded from work for the duration of the illness In health care settings, influenza testing should be done early in the outbreak to obtain the type and subtype of virus responsible Droplet Precautions with suspected or confirmed influenza should be implemented and authority to do so should be decided with nursing staff inclusion As detailed further under Droplet Precautions, suspected or confirmed influenza patients should be separated from asymptomatic patients Management including Infection Control Measures cont.-4
Management including Infection Control Measures cont.-5 • Health care staff movement between units and buildings should be restricted • In a setting or unit with influenza, patients without influenza should receive influenza antiviral prophylaxis unless contraindicated • Influenza antiviral therapy should be administered to those who are acutely ill with influenza within 48 hours of onset of illness unless contraindicated • Current inactivated influenza vaccine should be administered to unvaccinated patients and health care personnel if not contraindicated • Influenza antirviral prophylaxis should be offered to unvaccinated personnel for who it is not contraindicated and who work in the affected unit or who are caring for high-risk patients
Management including Infection Control Measures cont.-6 • Limit or eliminate elective medical and surgical admissions and restrict cardiovascular and pulmonary surgery to emergency cases only when influenza outbreaks especially those characterized by high attack rates and severe illness, occur in the community or acute care facility • Recommendations for peri-and post-partum settings may be found at http://www.cdc.gov/flu/professionals/peripostpartumguid.htm
Prophylaxis and Vaccination Antiviral agents may be used for prophylaxis, often in combination with the flu vaccine in an outbreak situation • Drugs used most often in the U.S. for prevention of flu are zanamivir and oseltamivir and are used particularly for those at high risk for complications from the flu or to prevent a person in close proximity from passing the flu to a high risk person
Prophylaxis and Vaccination cont.-2 Influenza vaccine • Current vaccines are inactivated influenza vacine administered by injection (Fluzone) and live attenuated, intranasal vaccine (FluMist) • In late July, 2008, the Advisory Committee in Immunization Practices (ACIP) issued their updated recommendations on prevention and control of influenza. The entire document is in Morbidity and Mortality Weekly Reports, Recommendations and Reports, 57 (early release) , 1-60, July 17, 2008
Prophylaxis and Vaccination cont.-3 Recommendations for 2008-2009 Influenza season are given below • It is recommended that all children aged 5-18 years old receive vaccination . • Children younger that 6 months should not be vaccinated. • Children and adolescents at higher risk for influenza complication are those: • aged 6 months – 4 years; • who have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological or metabolic disorders (including diabetes mellitus); • who are immunosuppressed (including immuno-suppresion caused my dedications or by human immunodeficiency virus); • who have any condition (e.g., cognitive dysfuction, spinal cord injuries, seizure disorders, or other neuromuscular disorders) that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration; • who are receiving long-term aspirin therapy who therefore might be at risk for experiencing Reye syndrome after influenza virus infection; • who are residents of chronic-care facilities; and, • who will be pregnant during the influenza season. Source: CDC, MMWR 57, 2008 pg 2
Prophylaxis and Vaccination cont.-4 For adults for the 2008-2009 flu season recommendations are for any adult and for and for all adults in the following groups because of higher risk: • Persons aged >= 50 years; • Women who will be pregnant during the influenza season; • Persons who have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological or metabolic disorders (including diabetes mellitus); • Persons who have immunosuppressions (including immunosuppression caused by medications or by human immunodeficiency virus); • Persons who have any condition (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders) that can compromise respiratory function or the handlig of respiratory secretions or that can increase the risk for aspiration; • Residents of nursing homes and other chronic-care facilities; • Health-care personnel; • Household contracts and caregivers of children aged <5 years and adults aged >= 50 years, with particular emphasis on vaccinating contracts of children aged <6 months; and, • Households contracts and caregivers of persons with medical conditions that put them athigh risk for severe complication from influenza. • Source: CDC, MMWR 57, 2008 pg 2
Nasal Spray Vaccine • Live, attenuated vaccine administered by nasal spray • Option for those healthy people ages 2 to 49 years old • Option for health care workers who take care of sick persons or care for babies under 6 months of age and who are healthy between 2 and 49 years of age • Not to be used in pregnancy • Not to be used by those who care for or live with someone with a compromised immune system or children less than 2 years of age
Table 1. Is It a Cold or the Flu?Source: National Institute of Allergy and Infectious Diseases
Special Notes on Avian Influenza Avian influenza viruses refers to those that are carried by birds, usually wild birds that when infected, shed virus in saliva, nasal secretions and feces. Birds or fowl become infected when they come into contact with secretions or excretions from infected birds most often through fecal-oral transmission. Transmission also occurs through contact with surfaces or materials such as feed, water, cages or dirt that are contaminated with the virus. Contaminated cages, for example, can carry the virus from one place to another. Avian influenza viruses vary in their degree of pathogenicity
"Hong Kong" Flu First documented direct transmission of an avian influenza (influenza A) virus (H5N1) to humans occurred in 1997 in Hong Kong Severe respiratory disease occurred in 18 healthy young adults and children and 6 died The outbreak was controlled by slaughter of the poultry population. More than 1.2 million chickens and 0.3 million other poultry were killed and imports of chickens from Hong Kong and China were banned by other countries. Quarantine and depopulation or culling of birds are common ways of control for the outbreak
"Hong Kong" Flu-2 Live poultry markets were source of the avian influenza virus strain H5N1 in this outbreak. In both influenza and SARS, the so-called “wet-markets” have been implicated as sources. This illustrates a cultural influence on emergence of infectious diseases since the preference of many Asian people for buying fresh foods at these markets have resulted in an increase in these types of markets. In New York City, these increased in number from 44 in 1994 to 80 in 2002.
Additional Recent Avian Flu Outbreaks In 1999, avian influenza viruses, H9N2, were isolated in Hong Kong from children with mild influenza In 2003, the avian influenza virus strain, H5N1, again emerged in 2 family members in Hong Kong after traveling in China. One died.
Additional Recent Avian Flu Outbreaks-2 In 2003, the avian influenza virus strain H7N7 occurred in poultry farms in the Netherlands, spreading to Germany and Belgium. Infection, mainly conjunctivitis occurred in 83 humans with 1 death. The outbreak was controlled by destroying over 30 million domestic poultry In 2003, the avian influenza virus, H9N2 was identified in a child in Hong Kong with influenza who recovered
Additional Recent Avian Flu Outbreaks-3 In 2003, an outbreak of avian influenza virus, H5N1, occurred in South Korea, and in 2004 emerged in Vietnam and Thailand. Human cases presented with severe respiratory infection and out of 23 known and confirmed cases, 18 died. Many countries banned the import of poultry products from the Asian countries affected. Other countries in which poultry were infected included Japan, Laos, China, Cambodia, and Indonesia.
Additional Recent Avian Flu Outbreaks-4 In 2004, an outbreak of avian influenza, H7N7 occurred in British Columbia, Canada. Infection has been reported in 5 humans whose major illness was conjunctivitis. In 2004-2005, east Asia again saw an outbreak of H5N1, particularly in Thailand, Cambodia, and Vietnam. By June 19, 2008, there were 385 reported human cases of avian flu and 243 reported deaths. Concern about pandemic flu has resulted in global efforts at prevention.
Documented human-to-human transmission of H5N1 has been noted but is limited. Of concern is that the virus could mutate to allow sustained person-to-person transmission. Transmission includes: Direct exposure to infected birds/poultry Exposure to surfaces contaminated with infected bird/poultry excretions, mostly through fecal-oral transmission Rare human-to-human transmission Symptoms Fever, over 38 deg. C or 100.4 deg. F Shortness of breath Cough Diarrhea
Suspecting Avian Influenza (H5N1) Laboratory testing should be prompted for a hospitalized or ambulatory patient with temperature over 38 deg. C AND with any one or more of the above symptoms AND a history of contact with domestic poultry such as a visit to a poultry farm or bird market Laboratory testing should be prompted for hospitalized patients with radiologically confirmed acute respiratory distress syndrome, pneumonia or other severe respiratory illness for which an alternate diagnosis has not been established AND history of travel to an area with documented H5N1 avian influenza within 10 days of the beginnings of symptoms.
Isolation Precautions For hospitalized patients who have or are suspected of having avian influenza A (H5N1), isolation precautions are same as for severe acute respiratory syndrome (SARS). These include: Careful hand hygiene before and after all patient contact Use gloves and gown for all patient contact Wear eye protection when within 3 feet (and perhaps 6 feet) of the patient
Isolation Precautions-2 Place patient in an airborne infection isolation room (AIIR). When entering the patient's room, use a fit tested respirator at least as protective as an N95 filtering-facepiece respirator approved by the National Institute for Occupational Health and Safety (NIOSH) Outpatients or hospitalized patients discharged in less than 14 days should be isolated in the home setting on the basis of principles for home isolation of SARS patients These precautions should be continued for 14 days after onset of symptoms until an alternative diagnosis is established or diagnostic test results indicate that the patient is not infected with inflenza A virus (CDC, 2004). Also see: http://www.cdc.gov/flu/avian/index.htm, and http://www.cdc.gov/ncidod/dhgp/pdf/isolation2007.pdf