​Kembara Xtra - Medicine - Influenza

​Kembara Xtra - Medicine - Influenza
Orthomyxovirus influenza types A and B-related acute fever infection characterized by inflammation of the nasal mucosa, throat, conjunctiva, and respiratory tract is an influenza.

Epidemiology 

Every year, throughout the fall and winter, influenza outbreaks can occur in both the Northern and Southern Hemispheres. The influenza virus can undergo an antigenic shift, or sudden change, which can result in viral strains with weak immune responses in a population, which can cause pandemic epidemics. All ages are susceptible to infection; antigenic drift refers to minor seasonal fluctuations. People with cardiovascular or pulmonary disease, Addison disease, or diabetes, as well as those who reside in nursing homes or other long-term care facilities, are notable demographic groups who are at risk for complications and hospitalization. These groups also include those who identify as American Indian or Alaska Native.
Since the majority of people do not seek medical attention, the incidence is difficult to determine.

The Centers for Disease Control and Prevention (CDC) in the US publish yearly surveillance data on prevalence.
The prevalence was projected to reach 38,000,000 positive tests during the 2019–2020 season, with 18,000,000 associated medical visits, 400,000 hospitalizations, and 22,000 deaths, 199 of which were among children. The percentage of positive tests varied between 26% and 30%. The fact that the 2020–2021 season took place amid the COVID–19 epidemic made it historic. Only 0.2% of tests were positive, according to the CDC. 
There was one pediatric flu-related fatality reported. At least 25 million more doses of immunization than in prior seasons were administered, setting a record. The prevention of influenza spread was probably aided by concurrent COVID-19 preventative measures such face masks, social isolation, and school closings.

Pathophysiology and Etiology 

Influenza strains A (the majority) and B, as well as the influenza A virus subtypes HxNx based on hemagglutinin and neuraminidase
spread by aerosolized droplets or contact with respiratory secretions. Hemagglutinin binds to columnar respiratory epithelium where replication occurs, and neuraminidase protein facilitates spread along respiratory epithelium. Incubation is 1 to 4 days; infected individuals are most contagious during peak symptoms.


Risk Elements 

- Crowded settings including nursing homes, barracks, classrooms, and jails are risk factors for disease transmission.
 Newborns, children, and seniors
- Chronic pulmonary disorders, especially in the third trimester of pregnancy
- Cardiovascular conditions, such as congestive heart failure (CHF) and valvular pathology - Metabolic disorder and severe obesity
- Immunosuppression; malignancy; hemoglobinopathies
- Neuromuscular conditions that impair the capacity to breathe and handle secretions

Prevention 

Unless there are contraindications, all people older than six months old should have a yearly vaccination. The CDC makes no distinction between different vaccination types.
The quadrivalent intranasal live attenuated influenza vaccine (LAIV) is authorized for use in healthy, non-pregnant people between the ages of 2 and 49.
There are two types of inactivated influenza vaccines (IIV): trivalent (IIV3) and quadrivalent (IIV4), each of which contains three or four influenza viruses. IIV is also offered as a recombinant hemagglutinin vaccine (RIV3), a high-dose, intradermal, cell culture-based (ccIV3), and an MF59-adjuvanted (aIIV3) formulation.
– An intranasal quadrivalent vaccine is called LAIV.

IIV is advised yearly for the following: - Every person older than 6 months
- As soon as the vaccination is available, it should be given annually.
- One to two weeks following the vaccine, protection sets in.
- Localized reaction at the vaccination site and a low-grade fever are two examples of moderate side effects.
- Intradermal formulation for ages 18 to 64 uses a small 30-gauge needle in a single-use prefilled syringe with 0.1 mL of vaccine; slightly higher local reactions when given intradermal. - Inactivated IM dose: 3 years of age: 0.5 mL; children 6 to 35 months of age: 0.25 mL. - One dosage each year, with the exception of children under the age of nine, who should have two doses (four weeks apart) in their first year of receiving the influenza vaccine. - Contraindication to vaccination Egg allergies do not require a skin test for the influenza vaccine, and severe allergies such as anaphylaxis to IIV components or allergies from eggs are not considered contraindications. All patients should be observed for 15 minutes following immunization. Patients with egg allergies can safely use RIV.
IIV-HD: high-dose quadrivalent IIV; contains four times as much antigen as IIV.
- Licensed for anyone under the age of 65 increases antibody levels but also slightly increases the frequencies of local reactions – It is not stated whether the Advisory Committee on Immunization Practices favors or opposes IIV-HD.
Antiviral prophylaxis is based on the most recent resistance trends each year; for patterns, visit https://www.cdc.gov/flu/ or contact your local health department.
During influenza season, for those with contraindications to vaccine who have been exposed to the virus; in high-risk groups who have not been vaccinated or need additional control measures during epidemics; not a replacement for vaccination unless vaccine is contraindicated; for staff and residents in nursing home outbreaks.
For immunocompromised individuals who are anticipated not to respond to immunization following virus exposure 

Child Safety Considerations
Vaccinate kids older than 6 months once a year.

 Suggest immunization for all family members with children under the age of six months.
For kids who require two doses, give the first one as soon as it's available and the second one by the end of October.
● Oseltamivir dosage for prophylaxis varies by weight and is advised by the CDC for children under three months of age; zanamivir is licensed for prophylaxis for children over five years of age at a dosage of two inhalations per day. Treatment for prophylaxis lasts for seven days. Amantadine and rimantadine are administered at a dosage of 5 mg/kg/day up to 150 mg in two evenly spaced doses for prophylaxis. Amantadine and rimantadine are now not advised due to resistance.


Pregnant women's issues

If unvaccinated throughout flu season, pregnant women should receive IIV or RIV. The CDC advises vaccination for all women who will be pregnant during flu season.
Pregnancy Category C includes oseltamivir, zanamivir, peramivir, rimantadine, and amantadine.


Bacterial pneumonia is a condition that is related.

Diagnosis 
Be on the lookout for: systemic symptoms; cough; inability to handle day-to-day activities; bed rest;

Introducing History 
Anorexia, fever (37.7–40.0°C), chills, sweats, malaise, myalgia, and arthralgia can all appear suddenly, especially within three days of the start of an illness.
Nonproductive cough, headache, sore throat, pharyngitis, rhinitis, and nasal congestion

Clinical Assessment 
Physical examinations should rule out complications such otitis media, pneumonia, sinusitis, and tracheobronchitis. Physical examinations are not specific for influenza.

Respiratory viral infections, such as SARS-CoV-2, respiratory syncytial virus, parainfluenza, adenovirus, and enterovirus ("influenza-like illness"), are differentially diagnosed. 
Less likely possibilities include severe acute respiratory syndrome, primary HIV infection, acute myeloid leukemia, tuberculosis, anthrax, and malaria. Infectious mononucleosis Coxsackievirus infections Viral or streptococcal tonsillitis Atypical mycoplasmal pneumonia Chlamydia pneumoniae Q fever.


Laboratory Results 

Initial examinations (lab, imaging)
Clinical results are used to determine whether to pursue diagnostic testing during the influenza season. Below are some of the testing modalities that are covered:
Rapid influenza diagnostic tests (RIDTs) for antigen detection
- All outpatient office-based testing should follow the Infectious Disease Society of America's recommended modality. - Within 10 to 15 minutes, detects viral antigens - Moderate sensitivity (80%), excellent specificity
Reverse transcription polymerase chain reaction (RTPCR) molecular assay with high specificity (90–95%)
There are commercially accessible fast enzyme-linked immunosorbent assay antigen assays called immunofluorescence. Rapid tests are used to identify influenza A and B. The sensitivity and specificity vary depending on the manufacturer, the influenza strain, and the patient's age. False-negative findings are frequent, especially during the height of the influenza season. Viral culture is not used in clinical therapy and is only used to monitor the antigenic and genetic properties of circulating influenza viruses for vaccine planning.


Tests in the Future & Special Considerations
Consider the following extra tests if the patient has serious symptoms at presentation: - Complete blood count: Typically displays mild leukopenia or a normal WBC count. Leukocytosis could be a sign of a bacterial problem.
- Full metabolic panel: Elevated liver enzymes or creatinine may be signs of serious illness.
- Chest x-ray if suspected pneumonia
Given the extensive overlap of symptoms, the concurrent SARS-CoV-2 pandemic presents a diagnostic problem during the flu season in 2020–2021. The frequency of coinfection is not yet known. The creation of commercially available combination tests for both SARS-CoV-2 and influenza A and B has been given emergency use authorization by the FDA.
Interpretation of Tests
The above-mentioned tests' positive and negative predictive results depend on local community prevalence. A positive test is more likely to indicate actual infection as prevalence rises (as influenza peaks), but a negative result is more likely to be erroneous.

Management 

Treatment for symptoms, including saline nasal spray, analgesic gargle, antipyretics, and analgesics; cool-mist or ultrasonic humidifiers to improve the moisture of inspired air; and advice on droplet precautions, such as donning a disposable medical mask around other people.
The usual duration of viral shedding in immunocompetent hosts is 5 days, and hospitalized patients may need oxygen or ventilatory assistance.

Medication 

Antiviral therapy is based on seasonal patterns of resistance. When given within the first 48 hours of a laboratory-confirmed (or highly suspected based on clinical signs) influenza illness, antivirals are most effective.
Patients at risk for complications (such as those with diabetes, CHD, COPD, asthma, etc.) should take antivirals within 48 hours of the onset of symptoms, and antivirals are also advised if the patient is hospitalized.
Baloxavir, oseltamivir, zanamivir, and peramivir are antivirals. Due to resistance, amantadine and rimantadine are currently not advised.
If a patient has recently started experiencing symptoms and wants to lessen the length of their sickness and their relatively low risk of consequences, they should think about taking antivirals.

For individuals lacking risk factors or indications of a lower respiratory tract infection, symptomatic therapy is preferred.
Effects include a 24-hour decrease in symptoms and a drop in the rate of complications.
- Baloxavir dose: oral, once-daily 40 mg to 80 mg for children under 80 kg and 80 mg for children over 80 kg. For children over 12 years, use adult dose.
- Age 7 years: 2 inhalations BID for 5 days with zanamivir.
- Age 13 years: 75 mg PO BID for 5 days with oseltamivir.
- 75 mg/day PO if there is severe renal impairment
Children under one year of age should take oseltamivir at the following doses: 15 kg, 30 mg BID; >15 to 23 kg, 45 mg BID; >23 to 40 kg, 60 mg BID; >40 kg, 75 mg BID.
Oseltamivir dosage: 3 mg/kg/dose BID for children under 1 year of age; 600 mg IV infusion over 15 to 30 minutes for people under the age of 18; Antipyretics; Acetaminophen: in children; Precautions.
- If the patient has COPD or asthma, zanamivir may cause bronchospasm; the patient should have a bronchodilator on hand.
- Due to its anticholinergic effects, amantadine should be taken with caution in patients with psychiatric, addiction-related, or neurologic illnesses since it may increase the likelihood of suicide attempts or worsen neurologic symptoms.
- Rimantadine may make seizures more likely in people who already have a seizure problem.
- If taken with food, the nausea and vomiting caused by oseltamivir may be less severe. - Serious skin reactions can be brought on by peramivir.
Ibuprofen or other NSAIDs for symptom alleviation Aspirin: should not be taken in children under the age of 16 due to the risk of Reye syndrome; certain antivirals should be reduced in dosage if creatinine clearance is below 60 mL/min. 
Except in situations with significant problems or in high-risk categories, outpatient treatment is adequate.


Admission 
Implement timely antiviral therapy for patients hospitalized with influenza-related illness, regardless of the length of prior symptom duration, and implement droplet precautions for both confirmed and suspected influenza.

Follow-up is usually not necessary in mild instances. In moderate or severe cases, follow-up is necessary until the symptoms and any secondary sequelae disappear.

Prognosis 
Excellent

Sepsis, primary viral or secondary bacterial pneumonia, myocarditis, encephalitis, myositis, rhabdomyolysis, acute sinusitis, croup, bronchitis, neonatal apnea, Reye syndrome, postinfluenza asthenia, COPD or CHF exacerbation, encephalopathy, and death are complications.

Aspects of Geriatrics
Elderly patients are more likely to experience complications that necessitate hospitalization.