Influenza Overview and Pathophysiology

A common genital tract infection affecting reproductive-aged women, caused by bacteria like Gardnerella vaginalis, Mobiluncus species, Prevotella species and Mycoplasma species.

A laboratory test using a 10% KOH solution that produces a temporary fishy odor when mixed with vaginal secretions, indicating a bacterial vaginitis.

A distinctive cell with irregular, speckled edges, often found in vaginal secretions during bacterial vaginitis.

A common side effect of metronidazole, characterized by a metallic taste in the mouth.

A self-limiting reaction that occurs within hours of treating early syphilis with antibiotics, usually involving fever, chills, headache, and muscle aches.

Small growths on the skin or mucous membranes, often appearing as rough, thick, cauliflower-like lesions, caused by the human papillomavirus (HPV).

A vaginal discharge that is thin, watery, and gray or white, often accompanied by a fishy odor.

A common side effect of the antibiotic metronidazole, characterized by an abnormal vaginal discharge.

A highly contagious viral illness spread through inhaling respiratory droplets, responsible for seasonal epidemics and major pandemics.

Classified into three types, A, B, and C, with subtypes based on surface proteins like hemagglutinin (H) and neuraminidase (N).

A protein on the influenza virus responsible for binding to respiratory epithelial cells, initiating infection.

A protein on the influenza virus responsible for cleaving the bond holding replicating virions, allowing for the spread of infection.

An inflammatory condition of the mucous membrane of the nose, often associated with a runny nose and congestion.

The period between exposure to a virus and the onset of symptoms.

The shedding of virus from the respiratory tract, making an infected person contagious.

A type of influenza vaccine containing inactive virus particles.

Indicates the number of influenza virus hemagglutinin (HA) antigens represented in the vaccine. A quadrivalent vaccine contains 4 antigens: A (H1N1), A (H3N2) and 2 B viruses. A trivalent vaccine contains 3 antigens: A (H1N1), A (H3N2) and one B virus.

Small changes in an influenza virus's gene that happen continuously over time as the virus replicates. It is caused by point mutations in the surface antigens of a particular subtype, leading to seasonal epidemics. This is why annual influenza vaccine updates are necessary.

Influenza virus acquires new hemagglutinin and/or neuraminidase via genetic reassortment rather than point mutations, resulting in a new subtype. This can lead to pandemics, like the 1918 Spanish flu.

A cap-dependent endonuclease inhibitor used for the treatment and prophylaxis of influenza A infection, administered orally. Baloxavir marboxil has a hepatic elimination pathway, meaning it is processed by the liver.

A neuraminidase inhibitor used for the treatment and prophylaxis of influenza A and B infection, administered orally. Oseltamivir has a renal elimination pathway, meaning it is processed by the kidneys.

A neuraminidase inhibitor used for the treatment and prophylaxis of influenza A and B infection, administered by inhalation. Zanamivir has a renal elimination pathway, meaning it is processed by the kidneys.

A neuraminidase inhibitor used for the treatment of influenza A and B infection, administered intravenously. Peramivir has a renal elimination pathway, meaning it is processed by the kidneys.

The SARS-CoV-2 virus enters host airway cells through a process called endocytosis. This process is facilitated by the viral S protein, which binds to the ACE2 receptor. Once inside the cell, the virus releases its RNA and uses the host cell's machinery to replicate itself and assemble new virions.

Early stage COVID-19 involves an inflammatory response triggered by infected cells, primarily bronchial epithelial cells, type 1 and 2 alveolar pneumocytes, and capillary endothelial cells. Infected type 2 pneumocytes release SARS-CoV-2 virus, which attracts T lymphocytes, monocytes, and neutrophils, leading to cytokine release that enhances inflammation (TNF-α, IL-1, IL-6).

Long COVID often involves persistent virus presence, autoimmunity, dysregulated microbiome, and tissue damage. It leads to ongoing health issues even after the initial infection has cleared.

Risk factors for developing Long COVID include exposure to SARS-CoV-2 variants, severe comorbidities, lack of vaccination, female gender, older age, and being a healthcare worker.

The most common clinical presentations of COVID-19 include fever, dry cough, shortness of breath (SOB), fatigue, muscle aches, nausea (N), vomiting (V), diarrhea, headache (HA), runny nose (rhinorrhea), anosmia (loss of smell), and ageusia (loss of taste).

Common lab abnormalities observed in hospitalized patients with COVID-19 include lymphopenia (low lymphocytes), elevated inflammatory markers (ESR, CRP, Ferritin, TNF-α, IL-1, IL-6), abnormal coagulation parameters (prolonged PT time, thrombocytopenia, D-dimer, low fibrinogen).

COVID-19 severity is classified as mild, moderate, severe, or critical. Mild cases involve mild symptoms and no need for hospitalization. Moderate cases develop dyspnea (SOB) in addition to mild symptoms. Severe cases involve hypoxemia (O2 sat less than or equal to 94% on room air) requiring oxygenation. Critical cases involve severe hypoxemia requiring ventilation.

Risk factors for severe COVID-19 include age over 60, BMI over 25, diabetes, high blood pressure, cardiovascular disease, chronic lung disease, cancer, and being immunocompromised.

Influenza A virus is further classified into subtypes based on two surface proteins: hemagglutinin (H) and neuraminidase (N). These proteins play crucial roles in the infection process.

Influenza A is the most common type and can cause severe illness requiring hospitalization. Influenza B can be less severe, and Influenza C is mild and infrequent.

Hemagglutinin binds to receptors on respiratory cells, allowing the virus to enter. Neuraminidase helps the virus exit infected cells, spreading the infection to new cells.

Influenza is spread through respiratory droplets released when an infected person coughs, sneezes, or talks. The virus can also be transmitted by touching contaminated surfaces and then touching your mouth, nose, or eyes.

The incubation period for influenza is typically 1-7 days, with most people showing symptoms within 2 days. During this time, the infected person can shed the virus and be contagious.

Common symptoms of influenza include fever, cough, sore throat, muscle aches, headache, fatigue, and congestion. These symptoms generally appear within a few days of infection.

The main types of influenza vaccines include inactivated influenza vaccine (IIV), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV). These vaccines work by introducing inactive or weakened virus particles into the body to trigger an immune response.

Influenza vaccines are important for protecting individuals and communities from influenza. They reduce the risk of severe illness, hospitalization, and death from influenza.

A common genital tract infection affecting reproductive-aged women, caused by bacteria like Gardnerella vaginalis, Mobiluncus species, Prevotella species and Mycoplasma species.

G.Vaginalis, Mobiluncus species, Prevotella species, Mycoplasma species

A laboratory test using a 10% KOH solution that produces a temporary "fishy" odor when mixed with vaginal secretions, indicating bacterial vaginitis.

A distinctive cell with irregular, speckled edges, often found in vaginal secretions during bacterial vaginitis.

Small growths on the skin or mucous membranes, often appearing as rough, thick, cauliflower-like lesions, caused by the human papillomavirus (HPV).

Patients diagnosed with HPV should be tested for cervical cancer.

Cryotherapy with liquid nitrogen is used consistently at all locations.

A benign, self-limited complication of anti-treponemal antibiotic therapy that develops within hours after treatment of early syphilis.

A self-limiting, flu-like reaction that occurs within hours of treating early syphilis with penicillin. Symptoms include fever, chills, headache, myalgias, tachycardia, and hypotension. It is NOT an allergic reaction.

A high Body Mass Index (BMI) over 25 is a risk factor for severe COVID-19 complications.

An antiviral medication used to treat influenza infections, particularly influenza A. It inhibits the viral neuraminidase enzyme.

A live attenuated influenza vaccine (LAIV) that is commonly given nasally, with a weakened strain of the influenza virus. It is generally safe and effective for most people.

A recent diagnosis of type 2 diabetes increases the risk of severe complications from COVID-19.

A condition that occurs when a person's immune system overreacts to a previously treated infection, leading to inflammation in various parts of the body. It is a rare but known side effect of penicillin treatment.

Managing symptoms and monitoring for disease progression are primary treatment goals for mild COVID-19.

Long-term side effects of mRNA COVID-19 vaccines are not well-established, and clinical studies show no evidence of severe long-term effects.

A serious adverse reaction to penicillin, causing a rapid heartbeat, sweating, and difficulty breathing, sometimes with a rash. It is life-threatening and requires immediate medical attention.

Paxlovid is an outpatient treatment option recommended for patients with COVID-19 and chronic kidney disease.

A type of antiviral medication that inhibits the replication of the influenza virus by blocking the action of the viral caps-dependent endonuclease.

Evusheld, a prophylactic treatment for COVID-19, is no longer recommended in the U.S.

Abacavir, an antiretroviral medication, should be avoided in patients with HIV who test positive for HLA-B *5701 because it can cause severe hypersensitivity reactions.

An HIV RNA level test confirms an HIV diagnosis, indicating the presence of the virus in the blood.

Tamiflu (oseltamivir) is a neuraminidase inhibitor used for the treatment and prevention of influenza A and B infection. It is an oral medication, primarily eliminated by the kidneys, and effective against both influenza A and B.

SARS-CoV-2 virus infects airway cells through a process called endocytosis. The virus uses its spike protein (S) to attach to the angiotensin-converting enzyme 2 (ACE2) receptor on host cells. Once inside the cell, the virus releases its RNA and uses the host cell machinery to replicate itself, producing more viral particles.

The early stage of Covid-19 involves an inflammatory response triggered by infected cells, mainly bronchial epithelial cells, type 1 and 2 alveolar pneumocytes, and capillary endothelial cells. Infected type 2 pneumocytes release SARS-CoV-2 virus, attracting immune cells like T lymphocytes, monocytes, and neutrophils. This leads to cytokine release, promoting inflammation, and ultimately lung damage.

A single dose of benzathine penicillin G given intramuscularly is the standard treatment for primary syphilis.

Acyclovir is the first-line therapy for treating genital herpes.

Metronidazole orally is the appropriate treatment for trichomoniasis.

Metronidazole oral 500mg BID x7 days is the recommended treatment for bacterial vaginosis.

Dark-field microscopy is the gold standard for diagnosing syphilis.

Azithromycin 1g orally single dose is the first-line treatment for chlamydia.

A "strawberry cervix" is a hallmark of trichomoniasis.

Rescreening in 3 months is recommended for patients with trichomoniasis due to the high risk of reinfection.