Influenza
Influenza is acommon infectious disease caused by the Influenza virus.
Presentation
Onset is sudden with fever, rhinorrhea, sore throat and headache. Severe myalgias coupled with respiratory tract symptoms are typical of influenza [7]. Patients may also have red, watery eyes and cough. There can also be tachycardia and dyspnea but with hypotension. Vomiting and diarrhea may also occur, but are rare findings associated with the disorder.
Immune System
Cervical Lymphadenopathy
- Signs and symptoms Signs and symptoms of pediatric seasonal influenza include the following: High fever Chills Myalgia Headache Fatigue Sore throat/pharyngitis Nasal congestion Rhinitis Nonproductive cough Cervical lymphadenopathy Conjunctivitis Conjunctivitis[emedicine.medscape.com]
Entire Body System
Fever
- Individuals with influenza were more likely to have cough (93% vs 80%), fever (68% vs 40%), cough and fever together (64% vs 33%), and/or nasal congestion (91% vs 81%) than those without influenza.[ncbi.nlm.nih.gov]
- Keep your child at home, except for doctor visits, for at least 24 hours after their fever is gone without the use of fever-reducing medicines. Make sure your child gets plenty of rest and clear fluids (water, broth, sports drinks, etc.).[cdc.gov]
- They may include body or muscle aches chills cough fever headache sore throat is it a cold or the flu? colds rarely cause a fever or headaches. Flu almost never causes an upset stomach.[icd9data.com]
- In studies limited to patients aged 60 years or older, the combination of fever, cough, and acute onset (LR, 5.4; 95% CI, 3.8-7.7), fever and cough (LR, 5.0; 95% CI, 3.5-6.9), fever alone (LR, 3.8; 95% CI, 2.8-5.0), malaise (LR, 2.6; 95% CI, 2.2-3.1),[dx.doi.org]
Chills
- They may include body or muscle aches chills cough fever headache sore throat is it a cold or the flu? colds rarely cause a fever or headaches. Flu almost never causes an upset stomach.[icd9data.com]
- Moderate to high fever Dry cough Headache Sore throat Chills Runny nose Loss of appetite Muscle aches Tiredness Many conditions — such as a common cold, diarrhea, and vomiting — are called "the flu," but are not influenza.[my.clevelandclinic.org]
- […] studies limited to patients aged 60 years or older, the combination of fever, cough, and acute onset (LR, 5.4; 95% CI, 3.8-7.7), fever and cough (LR, 5.0; 95% CI, 3.5-6.9), fever alone (LR, 3.8; 95% CI, 2.8-5.0), malaise (LR, 2.6; 95% CI, 2.2-3.1), and chills[dx.doi.org]
Weakness
- Despite treatment using intravenous immunoglobulin, her condition continued to get worse with new bulbar and respiratory muscle weakness.[ncbi.nlm.nih.gov]
- Signs of serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness. If they do occur, it is within a few minutes to a few hours after the shot.[web.archive.org]
- Among those individuals without influenza, weakness (94%) and myalgia (94%) were also commonly reported.[dx.doi.org]
Fatigue
- Abstract An 88-year-old woman presented to our emergency room with complaints of fever, coryza, barking cough and generalised fatigue for 2 days.[ncbi.nlm.nih.gov]
- Infected individuals usually experience a rapid onset of flu symptoms which typically include: muscle aches, high fever, head ache, chills, fatigue, dry cough and runny/stuffy nose.[3dscience.com]
- People who have flu often feel some or all of these symptoms: fever* cough sore throat runny or stuffy nose body aches headache chills fatigue sometimes diarrhea and vomiting *It’s important to note that not everyone with flu will have a fever.[cdc.gov]
- The dry cough and fatigue of influenza can last two to three weeks. Signs that influenza is getting worse include fever, shaking chills, and shortness of breath.[my.clevelandclinic.org]
- People infected with the seasonal flu virus feel miserable with fever, chills, muscle aches, coughing, congestion, headache and fatigue for a week or so.[niaid.nih.gov]
High Fever
- Moderate to high fever Dry cough Headache Sore throat Chills Runny nose Loss of appetite Muscle aches Tiredness Many conditions — such as a common cold, diarrhea, and vomiting — are called "the flu," but are not influenza.[my.clevelandclinic.org]
- fever lasting more than three days low blood pressure Possible complications of the flu pneumonia and respiratory failure worsening of chronic health conditions Other severe outcomes of the flu hospitalization death How the flu is diagnosed The flu is[canada.ca]
- Infected individuals usually experience a rapid onset of flu symptoms which typically include: muscle aches, high fever, head ache, chills, fatigue, dry cough and runny/stuffy nose.[3dscience.com]
- Signs and symptoms Seasonal influenza is characterized by a sudden onset of high fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and runny nose.[web.archive.org]
- In children without chronic health problems, it is a warning sign if they seem to recover from the flu but then relapse with a high fever, Dr. Frieden said. The relapse may be bacterial pneumonia , which must be treated with antibiotics . Dr.[nytimes.com]
Respiratoric
Cough
- Individuals with influenza were more likely to have cough (93% vs 80%), fever (68% vs 40%), cough and fever together (64% vs 33%), and/or nasal congestion (91% vs 81%) than those without influenza.[ncbi.nlm.nih.gov]
- Health-care Settings Symptomatic or Infected Patients During periods of increased respiratory infection activity in the community, masks should be offered as part of a respiratory hygiene/cough etiquette strategy to patients who are coughing or have other[web.archive.org]
- Individuals with influenza were more likely than those without influenza to have baseline cough (93% vs 80%), fever (68% vs 40%), and cough and fever together (64% vs 33%).[dx.doi.org]
Sneezing
- The mechanisms of symptoms of sore throat, rhinorrhoea, sneezing, nasal congestion, cough, watery eyes, and sinus pain are discussed, since these mechanisms are not dealt with in any detail in standard medical textbooks.[ncbi.nlm.nih.gov]
- How Flu Spreads Most experts believe that flu viruses spread mainly by tiny droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby.[cdc.gov]
- If you don't have a tissue, cough or sneeze into your elbow or sleeve. Wash your hands often with soap and water, especially after you cough or sneeze. If you don't have soap and water, you can use an alcohol-based hand cleaner.[girlshealth.gov]
- Contain your coughs and sneezes. Cover your mouth and nose when you sneeze or cough. To avoid contaminating your hands, cough or sneeze into a tissue or into the inner crook of your elbow. Avoid crowds.[mayoclinic.org]
- Yet differing symptoms of the cold are: sore throat; productive, phlegmy coughs; and sneezing.[3dscience.com]
Common Cold
- KEYWORDS: bioactivity; common cold; epidemiological study; influenza infection; tea catechins[ncbi.nlm.nih.gov]
- The common cold and influenza (flu) are the most common syndromes of infection in human beings.[ncbi.nlm.nih.gov]
- How can I tell the difference between a common cold and influenza? Many cold and influenza symptoms are similar. Both common cold and influenza are caused by viruses. There are some differences with influenza.[my.clevelandclinic.org]
- The flu can be serious or even deadly for elderly people, newborn babies, and people with certain chronic illnesses.symptoms of the flu come on suddenly and are worse than those of the common cold.[icd9data.com]
- Symptoms of the flu come on suddenly and are worse than those of the common cold. They may include Body or muscle aches Chills Cough Fever Headache Sore throat Is it a cold or the flu? Colds rarely cause a fever or headaches.[osap.org]
Nasal Congestion
- The mechanisms of symptoms of sore throat, rhinorrhoea, sneezing, nasal congestion, cough, watery eyes, and sinus pain are discussed, since these mechanisms are not dealt with in any detail in standard medical textbooks.[ncbi.nlm.nih.gov]
- Individuals with influenza were more likely to have cough (93% vs 80%), fever (68% vs 40%), cough and fever together (64% vs 33%), and/or nasal congestion (91% vs 81%) than those without influenza.[ncbi.nlm.nih.gov]
- For decreasing the likelihood of influenza, the absence of fever (LR, 0.40; 95% confidence interval [CI], 0.25-0.66), cough (LR, 0.42; 95% CI, 0.31-0.57), or nasal congestion (LR, 0.49; 95% CI, 0.42-0.59) were the only findings that had summary LRs less[dx.doi.org]
Dry Cough
- The dry cough and fatigue of influenza can last two to three weeks. Signs that influenza is getting worse include fever, shaking chills, and shortness of breath.[my.clevelandclinic.org]
- Infected individuals usually experience a rapid onset of flu symptoms which typically include: muscle aches, high fever, head ache, chills, fatigue, dry cough and runny/stuffy nose.[3dscience.com]
- A bout of the flu typically follows this pattern: Days 1–3: Sudden appearance of fever, headache, muscle pain and weakness, dry cough, sore throat and sometimes a stuffy nose. Day 4: Fever and muscle aches decrease.[betterhealth.vic.gov.au]
- They may include a scratchy sore throat, a burning sensation in the chest, a dry cough, and a runny nose. Later, the cough can become severe and bring up phlegm (sputum). The skin may be warm and flushed, especially on the face.[web.archive.org]
- The symptoms of flu can include: fever sore throat dry cough headache muscle and joint pain tiredness or extreme exhaustion In the elderly, fever may be absent and the only signs and symptoms of flu may be: confusion shortness of breath worsening of a[conditions.health.qld.gov.au]
Gastrointestinal
Abdominal Pain
- Abdominal pain, often severe enough to require differentiation from acute appendicitis, emerged as a dominant symptom, especially in older children.[ncbi.nlm.nih.gov]
- Fever 38 degrees C, cough and dyspnoea are the major symptoms on presentation, whereas gastrointestinal symptoms such as watery diarrhoea, vomiting and abdominal pain are common early in the course of the disease.[ncbi.nlm.nih.gov]
- Influenza A symptoms If you have influenza, you will have some or all of these symptoms: fever and chills headache and muscle aches feeling tired and weak sneezing, and stuffy or runny nose sore throat and cough Children may also have abdominal pain,[healthdirect.gov.au]
- Fever 38 C, cough and dyspnoea are the major symptoms on presentation, whereas gastrointestinal symptoms such as watery diarrhoea, vomiting and abdominal pain are common early in the course of the disease.[doi.org]
- pain in children Rare Mild Children are more likely to have gastrointestinal symptoms (nausea, vomiting and diarrhoea).[conditions.health.qld.gov.au]
Loss of Appetite
- Moderate to high fever Dry cough Headache Sore throat Chills Runny nose Loss of appetite Muscle aches Tiredness Many conditions — such as a common cold, diarrhea, and vomiting — are called "the flu," but are not influenza.[my.clevelandclinic.org]
- Usually they include the sudden appearance of: fever cough muscle aches and pain Other common symptoms may include: headache chills fatigue (tiredness) loss of appetite sore throat runny or stuffy nose Some people (especially children) may also have:[canada.ca]
- They might have: fever chills headache muscle aches dizziness loss of appetite tiredness cough sore throat runny nose nausea or vomiting weakness ear pain diarrhea Babies with the flu also may suddenly seem fussy or just "not look right."[kidshealth.org]
- Other common symptoms include sore throat, runny nose, headache, chills, loss of appetite, and fatigue. Some adults will also experience stomach ache, vomiting and diarrhea, but these symptoms are more common with children.[ccohs.ca]
Cardiovascular
Chest Pain
- You should also get help straight away if you feel chest pain , short of breath, dizzy or confused , or you are vomiting a lot.[healthdirect.gov.au]
- When to seek immediate attention Visit your nearest hospital if you develop any of these serious symptoms: shortness of breath, rapid breathing or difficulty breathing chest pain bluish or grey skin colour bloody or coloured mucus/spit sudden dizziness[canada.ca]
- In children Fast breathing or trouble breathing Bluish lips or face Ribs pulling in with each breath Chest pain Severe muscle pain (child refuses to walk) Dehydration (no urine for 8 hours, dry mouth, no tears when crying) Not alert or interacting when[cdc.gov]
- When to call the doctor You should consult your doctor if symptoms such as clouded/altered consciousness, breathlessness, or severe chest pain occur, and if you are concerned.[medinfo.co.uk]
Tachycardia
- There can also be tachycardia and dyspnea but with hypotension. Vomiting and diarrhea may also occur, but are rare findings associated with the disorder.[symptoma.com]
- Typical signs and symptoms include the following (not necessarily in order of prevalence): Cough and other respiratory symptoms Fever Sore throat Myalgias Headache Nasal discharge Weakness and severe fatigue Tachycardia Red, watery eyes Cough and other[emedicine.medscape.com]
- […] presentation of influenza virus infection varies, but it usually includes many of the following signs and symptoms: Fever Sore throat Myalgias Frontal or retro-orbital headache Nasal discharge Weakness and severe fatigue Cough and other respiratory symptoms Tachycardia[emedicine.com]
Eyes
Photophobia
- Red eyes were reported most frequently (94%) in cases of conjunctivitis, followed by tearful (77%), burning (64%), and itching (57%) eyes, and by pus in eyes (48%), photophobia (33%), and pain in eyes (31%).[dx.doi.org]
- Ocular symptoms develop in some patients with influenza and include photophobia, burning sensations, or pain upon motion. Some patients with influenza develop rhinitis of varying severity, but it is generally not the chief symptom.[emedicine.medscape.com]
Musculoskeletal
Myalgia
- It is marked by inflammation of the nasal mucosa; the pharynx; and conjunctiva, and by headache and severe, often generalized, myalgia.[icd9data.com]
- Other symptoms in some children included convulsions and acute myalgia.[ncbi.nlm.nih.gov]
- It was conducted in mainly unvaccinated (mean age, 35 years) adults and adolescents who had influenza-like illness, defined as having fever or feverishness plus at least 2 of the following influenza-like symptoms: headache, myalgia, cough, or sore throat[ncbi.nlm.nih.gov]
- It is marked by inflammation of the NASAL MUCOSA; the PHARYNX; and conjunctiva, and by headache and severe, often generalized, myalgia.[fpnotebook.com]
Arthralgia
- CASE PRESENTATION: This is a case of a 60-year-old man with chronic idiopathic pulmonary fibrosis, with fever, arthralgias and rash characterised by extensive erythematous plaques on his limbs and trunk 5â ‰days after influenza vaccination.[ncbi.nlm.nih.gov]
- We defined RIDT-negative influenza-like illness as RIDT-negative cases suspected by doctors due to clinical signs such as fever, headache, arthralgia, runny nose, and/or coughing as well as close contact with patients with influenza.[ajcn.org]
- Systemic adverse effects included cases of malaise, nausea, fever, arthralgia, rash, headache and more generalised and serious signs, such as neurological harms. Maternal outcomes and outcomes related to the course of pregnancy.[doi.org]
Back Pain
- (n 479) n (%) P‐value (Fishers exact) Vomiting 15 (3.2) 57 (11.9) Nausea 29 (6.2) 70 (14.6) Insomnia 3 (0.6) 7 (1.5) 0.34 Constipation 1 (0.2) 4 (0.8) 0.37 Back pain 2 (0.4) 4 (0.8) 0.69 Type of dizziness 2 (0.4) 4 (0.8) 0.69 Headache 11 (2.4) 13 (2.7[dx.doi.org]
Skin
Flushing
- The skin may be warm and flushed, especially on the face. The mouth and throat may redden, the eyes may water, and the whites of the eyes may become bloodshot. People, especially children, may have nausea and vomiting.[web.archive.org]
- Other common symptoms include: Body aches Chills Dizziness Flushed face Headache Lack of energy Nausea Vomiting Somewhere between day 2 and day 4 of the illness, the "whole body" symptoms begin to subside, and respiratory symptoms begin to increase.[web.archive.org]
- Other common symptoms include: Body aches Chills Dizziness Flushed face Headache Lack of energy Nausea and vomiting The fever, aches, and pains begin to go away on days 2 through 4.[medlineplus.gov]
Increased Sweating
- Only one immediate reaction was reported: one subject vaccinated with Agrippal S1 â experienced increased sweating and hypotension within the 30 minutes of vaccination.[scielo.org.ar]
Neurologic
Headache
- They may include body or muscle aches chills cough fever headache sore throat is it a cold or the flu? colds rarely cause a fever or headaches. Flu almost never causes an upset stomach.[icd9data.com]
- New knowledge of the effects of cytokines in human beings now helps to explain some of the symptoms of colds and flu that were previously in the realm of folklore rather than medicine-eg, fever, anorexia, malaise, chilliness, headache, and muscle aches[ncbi.nlm.nih.gov]
- Some antiviral drugs may be used if needed along with painkillers to relieve headaches and muscle pain.[symptoma.com]
- They may include Body or muscle aches Chills Cough Fever Headache Sore throat Is it a cold or the flu? Colds rarely cause a fever or headaches. Flu almost never causes an upset stomach.[fpnotebook.com]
Guillain-Barré Syndrome
- An increased risk of Guillain-Barré syndrome was seen in the period shortly after influenzalike illness, consistent with observations that Guillain-Barré syndrome is often preceded by a respiratory illness.[doi.org]
- GBS, Guillain-Barré syndrome; ILI, influenza-like illness.[doi.org]
- Cerebral Spinal Fluid study showed normal cell counts with elevated protein and nerve conduction study showed reduced diffuse compound muscle action potential amplitudes suggesting a diagnosis of Guillain-Barré syndrome.[ncbi.nlm.nih.gov]
- At the time, doctors thought the vaccine triggered Guillain-Barré syndrome, but more recent evidence makes this connection uncertain.[merck.com]
- We found no evidence of an association between seasonal inactivated vaccines and Guillain‐Barré syndrome or H1N1 pandemic vaccine and Guillain‐Barré syndrome.[doi.org]
Febrile Convulsions
- In specific cases, influenza vaccines were associated with serious harms such as narcolepsy and febrile convulsions.[doi.org]
- Additionally, influenza can cause a range of non‐respiratory complications, including febrile convulsions, Reye's syndrome, and myocarditis ( Treanor 2016 ; Wiselka 1994 ).[doi.org]
Workup
Laboratory tests
- Complete blood count
- Nasal or throat wash
- Nasal or throat swab
- PCR
- Cell-culture based tests
- FLU OIA test and QUICKVUE Influenza test based on detection of viral antigens by using monoclonal antibodies [7].
- ZSTATFLU test based on detection of viral neuraminidase using a substrate of colour-changing enzyme.
- Alere I Influenza A & B test a new point-of-care influenza test that delivers highly accurate molecular results in less than 15 minutes, approved by FDA in June 2014.
Imaging
Imaging studies are generally not required. In case of complications such as bacterial pneumonia, chest radiography may be advised.
Test results
A clinical examination and history is sufficient to form a diagnosis. Laboratory tests can help confirm the diagnosis.
Treatment
Pharmacological treatment
Lam et al suggested that cases of suspected severe influenza infection should be treated early and aggressively, even before diagnostic tests can be confirmed [8]. Commonly used antivirals include neuraminidase inhibitors like oseltamivir and zanamivir. M2 protein ion channel inhibitors, which are adamantine derivatives, like amantidine and rimantidine can also be used. Due to a marked increase in resistant isolates, the Advisory Committee on Immunization Practices (ACIP) recommends that adamantanes not be used in the United States for the treatment of influenza, except in selected circumstances [9].
Non-pharmacological treatment
It includes bed rest, the increased intake of fluids and a light but healthy diet during the flu. Typically, flu will resolve within a few days without any treatment.
Prognosis
Influenza has an excellent prognosis. Like all infectious diseases, it has a certain duration of action after which the symptoms begin to slowly subside. When there are no complications, acute symptoms subside within 3-7 days. Post-influenza asthenia may last for a few weeks.
The mortality associated with influenza is due to the complications associated with the disease. As a result of these complications, influenza can be deadly, especially for the weak, young and old, or chronically ill [6]. They include bacterial pneumonia, bronchitis, myositis, Reye syndrome in children, myocarditis and in some rare cases, multiorgan failure.
Etiology
Causative factors
There are 3 basic causative factors of this disease: Influenza A, B and C virus. They belong to the Orthomyxovirus family. Of the three, Influenza A virus is considered to be the most pathogenic and has at least 4 different recognized strains.
Transmission
Although the respiratory tract is presumed to be the primary site for the acquisition of infection, one study has suggested that transocular entry of influenza virus can occur [2]. Infection can be transmitted through sneezing and coughing and is thought to be transmitted primarily via large particle droplets (>5 microns) [3]. It is an airborne infection and close contact with a person with an active infection can transmit the disease.
Epidemiology
Incidence
According to a recent estimate by World Health Organization, 3 to 5 million cases of severe cases occur worldwide annually. 250,000 to 500,000 deaths have also been reported [4].
Age
Influenza affects young and old alike. Elderly patients with low immunity and immunocompromised individuals are particularly susceptible.
Sex
Influenza occurs equally in both sexes.
Pathophysiology
Influenza A is a genetically labile virus with mutation rates as high as 300 times that of other microbes [5]. It is known to cause pandemics worldwide. Influenza B is usually associated with smaller outbreaks. Influenza C has been reported to cause epidemics in children but mainly causes only mild respiratory infections.
After the virus has been inhaled, an incubation period of 12-24 hours ensues. A special substance present in the form of spikes on the virus is hemagglutinin. It binds to cell surface receptors to initiate infection. Another substance, neuroaminidase, present in the virus is an enzyme that degrades the protective layer of mucus in the respiratory tract. It also cleaves neuraminic acid to release progeny virus from the infected cells. It is the action of these two moieties that result in the symptoms of influenza as well as necrosis of the superficial layers of the respiratory epithelium.
Prevention
The main mode of prevention is the influenza vaccine that typically contains two strains of Influenza A virus and one strain of Influenza B virus. Annual influenza vaccination is an important public health measure for preventing influenza infection [10]. Currently, there are two types of vaccines available in the US. First is a killed vaccine containing purified protein subunits of the virus (hemagglutinin and neuraminidase). It has two versions, namely ‘split virus’ vaccine and ‘purified subunit’ vaccine. Both are administered intramuscularly. The second type is a live vaccine which contains temperature sensitive mutants of Influenza A and B virus.
Some antiviral drugs may also help in preventing the infection, particularly in elderly, non-vaccinated individuals.
Summary
Influenza is a common household occurrence. Commonly known as the ‘flu’, influenza is an infectious disease caused by a virus. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease [1]. It has been known to cause epidemics and pandemics worldwide. Influenza has a seasonal variation, being much more common in winter and in the rainy season. It has variations which pose to be a much bigger threat like the avian flu and the swine flu, however, our section deals with the general concept of this disease.
Patient Information
Definition
Influenza, simply called the flu, is a very common infectious disease of viral origin.
Cause
It is caused by Influenza virus A, B or C. Transmission is through airborne aerosol droplets that contain the infectious particles. It can be spread by close contact with a person having an active infection. Simple acts such as coughing, sneezing and even laughing can transmit the infection.
Signs and symptoms
Signs and symptoms include sudden high grade fever associated with chills, sore throat, runny nose and cough. Headache and body aches are commonly present. There may also be difficulty in breathing, increased heart rate, vomiting and diarrhea. Symptoms may go away on their own eventually within 3-7 days.
Diagnosis
Diagnosis is made based on clinical findings. Some laboratory tests may be performed to confirm the diagnosis. In case of complications such as pneumonia, a more through series of tests will be required.
Treatment
Treatment is not necessary as symptoms often resolve by themselves. Bed rest and fluids help speed up recovery. Some antiviral drugs may be used if needed along with painkillers to relieve headaches and muscle pain.
References
Article
- Eccles R. Understanding the symptoms of the common cold and influenza. Lancet Infect Dis 5 (11): 718–25, 2005.
- Bischoff WE, Reid T, Russell GB, Peters TR. Transocular entry of seasonal influenza-attenuated virus aerosols and the efficacy of n95 respirators, surgical masks, and eye protection in humans. J Infect Dis 2011; 204:193.
- Mubareka S, Lowen AC, Steel J, et al. Transmission of influenza virus via aerosols and fomites in the guinea pig model. J Infect Dis 2009; 199:858.
- Lozano R. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 380 (9859): 2095–128, 2012
- Drake JW. Rates of spontaneous mutation among RNA viruses. Proc Natl Acad Sci U S A. May 1 1993;90(9):4171-5.
- Hilleman M. Realities and enigmas of human viral influenza: pathogenesis, epidemiology and control. Vaccine. Aug 2002. 20 (25–26): 3068–87.
- Warren L. Review of Medical Microbiology and Immunology. 11th ed. Pa: McGraw Hill, 2010. ISBN 978-0-07-170028-3.
- Lam J, Nikhanj J, Ngab T, et al. Severe Cases of Pandemic H1N1 Pneumonia and Respiratory Failure Requiring Intensive Care. J Intensive Care Med. 5;26:318-25.
- Fiore AE, Fry A, Shay D, et al. Antiviral agents for the treatment and chemoprophylaxis of influenza --- recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2011; 60:1.
- Grohskopf LA, Olsen SJ, Sokolow LZ, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP) -- United States, 2014-15 influenza season. MMWR Morb Mortal Wkly Rep 2014; 63:691.