viruses Flashcards
outline how viruses cause pathogenic effects
1) cell lysis
- may cause death of the host cell as it breaks it apart as viral particles leave
- occurs in animal cells
- infected cells may also be killed by T lymphocytes and remains engulfed by phagocytosis
2) trigger cells to become cancerous
- may activate pro-oncogenes or deactivate tumour suppressor genes
3) supress the immune system
- may infect T helper cells which hover time are destroyed and decrease numbers
give some examples of viral diseases
1) influenza
2) small pox
3) HIV
give some examples of viral diseases
1) influenza
2) small pox
3) HIV
describe the influenza virus
- three different subgroups= A, B and C each with different antigenic types
- A is most common
- antigenic types based on differences in two surface proteins
H= haemagglutinin = entering the cell
N= neuraminidase = leaving the cell
how is influenza spread
1) by droplets
2) infects the cells of the upper respiratory tract which generate aerosols
what are the symptoms of influenza
1_ onset of a headache
2) chills and a cough
3) fever
4) loss of appetite
5) muscle ache and tiredness
how is influenza treated
1) rest and fluids
2) antiviral drugs (used rarely)
how is influenza prevented
1) vaccination programmes - annual
- 70-80% effective
- only lasts for a year as the virus is always mutating slighlty
what virus causes small pox
variola major
how is small pox spread
1) via saliva, persons to person contact or inhaled
what are the symptoms of small pox
1) rash followed by fluid filled blisters leaving scars
2) scars on the cornea result in blindness
how is small pox treated
1) infected individual is isolated
2) given fluid and drugs to control the fever
3) may be given antibiotics to control secondary bacterial infections
how was small pox prevented and eradicated
1) vaccination programmes
2) little mutation rate so little antigenic variation
