Understanding Viruses and Antivirals

Viruses

• Virology is the branch of microbiology studying viruses
• Viruses can infect animals, plants, and bacteria
• Viruses can have single or double strand DNA & RNA
• They assemble themselves rather than replicating
• They assemble new virions using host cell parts
• Viruses travel from host to host through bodily fluids or air
• Viruses can kill their host
• Viruses are made of host components which makes them difficult to kill
• Antivirals will harm healthy host cells

Stopping Viral Infections

• Antivirals and vaccines help stop infections
• Prevention helps stop viral infections

Antivirals

• Antivirals are virustatic, meaning they don't destroy the virus
• They slow down proliferation which allows the host's immune system to attack
• Antivirals can stop the virus from attaching to a host cell by blocking receptor sites
• Can stop the replication process within the host cell, inhibiting virion components
• Disrupt virion particle assembly within the host cell, creating incomplete virions
• Antivirals inhibit replication by suppressing viral DNA/RNA synthesis
• They may attach to the host cell's DNA and disrupt the replication process
• They inhibit virus's ability to assemble itself properly, disrupting protein synthesis

Herpes Viruses

• Herpes viruses are a family of DNA viruses impacting humans
• Includes Herpes simplex, Herpes zoster, Varicella zoster

Herpes simplex

• Herpes simplex Type 1 causes disease of the mouth, face, skin, esophagus, and brain
• It is transmitted through oral secretions
• Herpes simplex Type 2 causes disease of the rectum, genitals, and meninges
• Transmitted through sexual contact, from mother to baby during birth
• Valtrex (valacyclovir), Famvir (famciclovir), Zovirax (acyclovir), Abreva can be used to treat cold sores
• Valtrex (valacyclovir), Famvir (famciclovir), Zovirax (acyclovir) can be used to treat genital herpes

Herpes zoster

• Shingles is caused by herpes zoster
• Shingles presents as lesions on torso, arms, legs
• It is reactivation of latent varicella infection

Varicella zoster

• Varicella causes Chickenpox
• Chickenpox is a common childhood infection
• The body usually produces immunity against reinfection

Shingles

• Persons aged 60 years or older have increased risk for shingles
• The virus re-activates and travels via nerve fibers to the skin surface
• Shingles consists of painful skin lesions that form blisters
• Blisters ooze fluid and heal in 3-4 weeks
• Contagious while sores are open
• Exposure to active shingles can cause chickenpox in uninfected individuals
• These individuals later have risk of developing shingles

Prevention of Varicella Zoster Virus

• The varicella (chickenpox) vaccine is given at 15 months
• It protects against contraction of chickenpox
• Older formulations are stored at -15°C with diluent in fridge or at room temperature
• Newer formulations have both active ingredient and diluent stored in the refrigerator
• Varicella vaccines must be dispensed with both the active vaccine ingredient and sterile diluent
• Some varicella vaccines come with active ingredient in one box and diluent in another

Treatment for Shingles

• Treatment involves lessening symptoms and shortening duration
• Can use Zovirax (acyclovir)
• A complication of shingles is post-herpetic neuralgia, manifesting as chronic nerve pain
• Post-herpetic neuralgia is difficult to treat, especially with conventional manufactured medications
• Can treat topically or transdermally with capsaicin, lidocaine, amitriptyline, or gabapentin

Prevention of Shingles

• Shingrix is a vaccine effective in preventing shingles and complications like postherpetic neuralgia
• It is recommended for adults 50 and older, regardless of prior shingles or chickenpox
• The vaccine is administered in two doses, 2-6 months apart
• Shingrix is administered intramuscularly with a 1- to 1.5-inch needle in the upper arm's deltoid region
• Prescriptions must be written by an authorized prescriber
• Both Shingrix vials must be refrigerated at 2-8°C -Is covered by most private insurance plans
• Patient should fill out vaccine intake form

Common Cold & Influenza

• Common cold and influenza are both respiratory infections with no cure
• Some herbal products can help prevent and decrease the duration of the infection
• OTC medications can help relieve some symptoms

Common Cold

• There are no vaccines for the common cold
• Common cold is caused by Rhinovirus/adenovirus and lasts 3-14 days
• It has a low risk of complications
• Symptoms include: sore throat, cough, nasal congestion

Influenza

• Vaccination for influenza is availabl
• Influenza affects the lower respiratory system
• It has a risk of developing complications
• Symptoms include: sore throat, cough, fever, weakness, & muscle aches
• It has a 1-3 day incubation and is transmitted via air droplets

Herbal Remedies & Over-the-Counter Medications

• Cold FX, Vitamin C, Zinc, & Guaifenisin are all herbal remedies or medications used to treat illnesses
• Guaifenisin is and expectorant, it is used to help cough out phlegm from airways
• Dextromethorphan is a cough suppressant
• Dextromethorphan should be avoided by those with high blood pressure and/or COPD
• Watch for patients with diabetes choosing cough and cold products

Important Considerations

• Analgesics like acetaminophen and ibuprofen are in over-the-counter medications
• The maximum daily dose of acetaminophen is 4g, be cautious of how much patient intakes
• Patients taking warfarin should avoid NSAIDs

Prescription Antivirals

• These inhibit the enzyme breaking the bond that holds the virus to it's host cell
• Relenza (zanamivir) & Tamiflu (Oseltamivir) are both antiviral brand names

Common Cold & Influenza Prevention

• Prevention is key
• Healthy hand hygiene is important
• In hospital pharmacies, it's important to take precautions
• Wear mask, gowns, & use gloves when required
• Pay attention when entering patient rooms, wash hands, and use hand sanitizer
• Precautions can be to protect workers from patients, or protect vulnerable patients

H1N1 - Swine Flu

• H1N1 is transmitted through airborne droplets
• Symptoms include fever, cough, headache, muscle and joint pain, sore throat, runny nose, and diarrhea
• It can cause severe illness and death in high-risk groups
• High-risk groups include patients in their second and third trimester

HIV / AIDS

• HIV is the Human Immunodeficiency Virus and AIDS is Acquired Immunodeficiency Syndrome
• HIV is a blood borne virus spread through bodily fluids or sexual contact
• It is spread through sexual contact, contaminated needles, and blood
• It decreases T-cells
• Leads to opportunistic infections
• Patients can die from infections that are HIV/AIDS complications
• Patients can be HIV positive but not have AIDS
• HIV/AIDS is always contagious

Treatment of HIV

• Antiretrovirals for HIV are used because HIV is a retrovirus
• These medications delay the progression to AIDS
• Examples: Retrovir (Zidovudine), Viramune (Nevirapine), Atripla (Efavirenz), Invirase (Saquinavir), and Reyataz (Atazanavir)

Human Papillomavirus (HPV)

• HPV is a group of viruses that cause warts (common & genital)
• Increases risk of cervical cancer
• HPV Vaccine is available

Polio

• Polio has three forms
  • Asymptomatic exhibits no symptoms
  • Mild cases cause infection of the meninges
  • Paralytic cases cause paralysis
• Polio is highly contagious
• Transmitted through oral contact, fecal contact, or contaminated food and water
• It affects the nervous system by destroying afferent nerves

Immunity

• Live vaccines must be attenuated, or weakened
• Live vaccines have a small risk of developing infection because they are live, however, it does create lifelong immunity
• Inactive vaccines have less risk of developing infection however it requires booster shots
• Active immunity is when a body is exposed to a disease, or they are administered a live vaccine
• Passive immunity does need action of the body -Is received through a mother to child

Importance of Vaccinations

• Vaccinations protect communities from diseases
• At-risk populations must be vaccinated
  • Children
  • Elderly
  • Chemo patients
  • Transplant patients
  • AIDS patients
  • Patients with compromised immune systems

Vaccinations and What They Protect Against

• Dukoral protects against Cholera & Traveler's Diarrhea
• Adacel protects against Tetanus, Diptheria, & Pertussis
• Td Adsorbed protects against Tetanus and Diptheria
• Havrix protects against Hepatitis A
• Twinrix protects against Hepatitis A & B
• Engerix protects against Hepatitus B
• Gardasil protects against HPV
• MMR protects against Measles, Mumps, & Rubella
• Rabavert protects against Rabies
• Typhim protects against Typhoid
• YF-Vax protects against Yellow Fever

Storage of Vaccines

• They must be stored in fridge -Fridge temperature must lie between 2-8°C
• Monitor fridge temperature & record in a logbook
• Advise patients picking vaccines to get it in a fridge ASAP, or have it injected immediately
• Check your cold chain