L18: Seasonal Influenza & Chicken Pox Flashcards
Def of Seasonal influenza
Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world
Global Epidemeology of Seasonal influenza
- According to WHO, from 7th August to 20th August 2017 therewere 7483 +ve cases represent about 15.3% .
- 75% of these +ve cases were type A(H3N2), 13% type B & 12% type A(H1N1)
National Epidemeology of Seasonal influenza
Seasonal epidemics occur mainly during winter, from November to April
Epidemic Threshold of Seasonal influenza
variable and is calculated based on virus activity in previous years.
Suspected Case of Seasonal influenza
- Case ILI (influenzas like illness): any patient with fever ˃38˚C associated with cough more than 10 days without any other causes (outpatient clinic).
- Sever acute respiratory infection SARI: any patient with fever ˃38 ˚C associated with cough more than 10 days without any other causes (hospitalized patient).
Probable Case of Seasonal influenza
None
Confirmed Case of Seasonal influenza
positive PCR
CA of Seasonal influenza
CA of Seasonal influenza
- Influenza A Virus
- Further classified into subtypes according to the combinations of the hemagglutinin (HA) and
the neuraminidase (NA), the proteins on the surface of the virus. - Currently circulating in humans are subtype A(H1N1) and A(H3N2) influenza viruses.
- Only influenza type A viruses are known to
have caused pandemics. It infects human and animals.
CA of Seasonal influenza
- Influenza B Virus
- are not classified into subtypes
- associated with outbreak or widespread epidemic.
- It infects human only
CA of Seasonal influenza
- Influenza C Virus
- detected less frequently
- usually causes mild infections
- thus does not present public health importance
MOT of Seasonal influenza
❶ When an infected person coughs or sneezes, droplets containing viruses (infectious droplets) are dispersed into the air and can spread up to one meter, and infect persons in proximity who breathe these droplets in
❷ The virus can also be spread by hands contaminated with influenza viruses
❸ Freshly contaminated articles &fomite
Reservoir of Seasonal influenza
❶ human (main reservoir)
❷ swine & avian reservoir
IP of Seasonal influenza
the average for influenza is 2 days, typically ranging from 1 to 4 days.
Infectivity Period of Seasonal influenza
in the first 3-4 days after clinical onset in adult
up to 7 days in children .
Susceptible age for Seasonal influenza
All age groups can be affected
People at greater risk of severe disease or complication when infected are ……
General Prevention of Seosanal Influenza
(as mentioned in general preventive measures of droplet inf)
Specific Preventon of Seasonal Influenza
- Active immunization
- Chemoprophylaxis
Active Immunization of Seasonal Influenza
- inactivated influenza vaccines
- Live attenuated intranasal influenza vaccines
Nature of inactivated influenza vaccines
killed vaccines contain influenza A(H3N2), pandemic A(H1N1) and B strain
Immunity in inactivated influenza vaccines
Immunity from vaccination wanes over time so annual vaccination is recommended to protect against influenza before influenza season, in
late autumn & early winter
Dose of inactivated influenza vaccines
❶ non immunized: 2 doses, 4 weeks apart, 0.5ml each, IM.
❷ Immunized before: single dose is sufficient
Indication of inactivated influenza vaccines
❶ pregnant women at any stage of pregnancy
❷ children aged between 6 months to 5 years
❸ elderly individuals (aged more than 65 years)
❹ individuals with chronic medical conditions
❺ health-care worker
Protective Value of inactivated influenza vaccines
80% against the circulating strain of
virus.
Nature of Live attenuated intranasal influenza vaccines
Live attenuated vaccines, contains two Subtypes A&B
Dose of Live attenuated intranasal influenza vaccines
0.5 ml by intranasal spraying
Immunity of Live attenuated intranasal influenza vaccines
It produces local & systemic immunity
Indication of Live attenuated intranasal
influenza vaccines
Only for healthy people aged 5-49 years.
Chemoprophylaxis in Seasonal Influenza
Uses of Remantadine hydrochloride
chemoprophylaxis of influenzas A but not B .
Indictions of Remantadine hydrochloride
high risk groups such as elderly, children& chronic diseases .
CI of Remantadine hydrochloride
patient with CNS, neurological or psychological disorders
Case Control measures of Seasonal Influenza
Contact Control Measures in Seasonal Influenza
❶ Surveillance for IP.
❷ Chemoprophylaxis: antiviral in high risk contacts.
Epidemic Measures in Seasonal Influenza
❶ Health education of the public
❷ Immunization for high risk groups& adequate supplies of antiviral drugs & vaccines.
❸ Surveillance of the community.
Def of Chicken pox
Chickenpox is a highly contagious viral infection that causes fever and an itchy rash with spots all over the body
Global Epi of Chicken pox
Epidemic worldwide, it mainly affects kids, but adults can get it, too., because of absence of varicella-zoster vaccination program
National Epi of Chicken pox
- Endemics occurs during winter & spring among small clusters (schools &camps)
- In Egypt, 4876 cases were registered in 2015
Suspected Case of Chicken pox
- fever ˃38.5 ˚C, itchy, blister-like rash.
- The rash first appears on the chest, back, and face, and then spreads over the entire body without any other reason .
Probable Case in Chicken pox
None
Confirmed Case of Chicken pox
positive PCR, vesicular swabs or scrapings and scabs from crusted lesions can be used to identify varicella-zoster virus DNA by PCR.
Causative Agent of Chicken pox
Varicella Zoster Virus (VZV) - member of the family herpes virus
Reservoir for Chicken pox
Human is the only reservoir (no carriers)
MOT of Chicken pox
❶ Direct droplet infection.
❷ Direct contact infection with ruptured vesicular fluid
IP of Chicken pox
2-3 Wks
Infectivity Period of Chicken pox
- 1-2 days before the rash appears, and for as long as 3-10 days until all lesions are crusted.
Susceptible Age for Chicken pox
- Varicella is generally a mild disease in children, and
- most people recover without serious complications.
- However no age is exempted; disease is more sever in adult .
Immunity from Chicken pox
Infection gives lifelong immunity.
Infectivity of Chicken pox
- highly infectious, over 80% of non-immune contacts of a case will be infected.
General prevention of Chicken pox
mentioned in general preventive measures of droplet inf
Specific Prevention of Chicken pox
Active and Passive
Active Vx for Chicken pox
Passive Immunity for Chicken pox
Seroprophylaxis
- Human specific Ig of varicella zoster to high-risk contacts.
Case control Measures in Chicken pox
Contact control Measures in Chicken pox
