viral infections Flashcards
1
Q
viruses
A
- acellular pathogens that invade living cells (can’t survive without a host)
- either kill host cell or alter its functions
- composed of nucleic acid (DNA or RNA) surrounded by protein coat
- viruses are microscopic agents visible only with an electron microscope
- lack enzymes for energy production & protein synthesis
- cannot grow or reproduce independently & need a host cell to replicate
2
Q
parasites
A
- organisms that live on or in a living host; relationship benefits the parasite & harms the host
3
Q
mechanism of viral infection
A
- viruses invade host cells & shed their protein coats
- genetic material of the virus takes control of the host cell, directing it to produce more viruses
- immune system fights viruses by producing substances such as interferon, which also cause symptoms of viral illnesses
4
Q
contagious diseases
A
- viral diseases are the most common forms of contagious diseases
- contagious diseases can be transmitted from one person to another, often through respiratory droplets or hand-to-hand contact
- examples; common cold & influenza
5
Q
common cold
A
- caused by over 200 different viruses, including rhinoviruses & coronaviruses
- transmission primarily through hand-to-hand contact
- prevention; frequent hand washing & avoiding touching the face after contact with others
- symptoms; sore throat, runny nose, muscle aches, thick nasal discharge
- OTC remedies can alleviate symptoms but do not cure viral infection
- not caused by exposure to cold weather or being chilled, but more colds occur in fall and winter due to closer indoor contact
6
Q
influenza (flu)
A
- serious respiratory tract infection caused by influenza virus
- highly infectious & adaptable; form changes so easily that every year new strains arise, making treatment difficult
- symptoms; fever, extreme fatigue, headache, cough, muscle aches
- spread via respiratory droplets
- prevention; annual vaccination with vaccine updated each year to match circulating strains
- treatment; medications can shorten the duration of illness if taken within one to two days of symptom onset
- complications; can include pneumonia & other life-threatening conditions
- highest infection rates are in children
- compared with the common cold, influenza is more serious
7
Q
measles & rubella
A
- characterized by rash & fever
- can cause severe complications like liver or brain infection or pneumonia
- highly contagious
- effective vaccination has significantly reduced cases
- rubella (German measles);
- mild illness but can cause severe birth defects if a pregnant woman is infected
- vaccination has reduced incidence
8
Q
mumps
A
- causes swelling of the salivary glands
- an lead to meningitis and, in males, inflammation of the testes
- cases have decreased due to vaccination
9
Q
chickenpox, coldsores, & herpesvirus infections
A
- herpesviruses = large group of viruses that remain latent in body & can reactivate periodically
- once infected, host is never free of the virus
- virus lies latent within certain cells & becomes active periodically, producing symptoms
- responsible for cold sores, mononucleosis, chicken pox, & STI herpes; frequently cause
latent infections
10
Q
varicella-zoster virus
A
- included in herpesviruses
- causes chicken pox & shingles
- highly contagious childhood disease characterized by itchy rash made up of small blisters
- complications more likely to occur in young infants & adults
11
Q
epstein-barr virus (EBV), aka mono
A
- included in herpesviruses
- causes infectious mononucleosis
- spread by intimate contact with saliva of infected person
- fever, sore throat, swollen lymph nodes, & fatigue
12
Q
cytomegalovirus (CMV) & human herpesvirus 8 (HHV-8)
A
- included in herpesviruses
- can cause severe infections in immunocompromised individuals
- CMV injects lungs, brain, colon, & eyes
- HHV-8linked to Kaposi’s sarcoma
13
Q
viral encephalitis
A
- inflammation of brain tissue caused by viral infection
- causes; HSV-1, HIV, mosquito-borne viruses
- symptoms; fever, headache, nausea, lethargy, memory loss, seizures, possible permanent brain damage or death
14
Q
viral hepatitis
A
- used to describe several different infections that cause inflammation of liver
- hepatitis is usually caused by one of the three most common hepatitis viruses;
- effective vaccines for hep A & B but new cases occur each year
- symptoms; fatigue, jaundice, abdominal pain, loss of appetite, nausea, diarrhea
15
Q
hepatitis A virus (HAV)
A
- mild, transmitted by contaminated food or water
