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Viral Droplet Infections
Dr. Abd El hamied
Mohamed Abd El hamied
Lecturer of Occupational
Health & Industrial
Medicine
Viral Droplet
Infections
 Seasonal Influenza
 Avian Influenza
 Swine Influenza
Seasonal
influenza
Avian
Influenza
Swine flu
Acute
highly Infectious viral Acute infection
infectious
viral disease of birds. caused by Type
disease
Some
(AI) A
influenza
characterized by viruses can cause viruses (H1N1
fever, general & infections
subtype).
catarrhal
(clinical
or
manifestations. subclinical)
in
humans.
Public health significance:
Seasonal influenza
Occurs as sporadic cases, outbreaks, epidemics &
pandemics.
In the last century, there are 3 pandemics.
During epidemics, clinical attack rates range from
10-20% in general population to >50% in closed
population.
Influenza epidemics evolve rapidly, spread widely
with serious complications & death especially in
elderly & patients with chronic debilitated
diseases.
Avian Influenza
1st direct bird to human spread of H5NI occurred
in Hong Kong in 1997.
Re-emergence in December 2003 & spread from
Asia to Europe & Africa (pandemic), resulting in
millions of poultry infections, hundreds of human
cases & many human deaths.
In Egypt, 1st direct bird to human spread of H5N1
occurred in 2006 & total cases in 2009 were 85
with a total deaths of 27 (CFR is 31.7%)
Globally ► general CFR reached 50%.
Swine flu
 In April 2009 ►WHO declared a "public health
emergency of international concern" when 1st 2
cases of H1N1 virus were reported in US,
followed by hundreds of cases in Mexico.
 In April 2010,CFR was at least 17.700 deaths
worldwide.
 Risk factors :
extremities of age
pregnant females
individuals with syst emic diseases.
 In Egypt in 2009 → 808 cases were confirmed
with 2 deaths (CFR around 0.2%).
 In Aug-2010, WHO declared that swine flu
pandemic officially over.
Causative agent
Seasonal influenza
Type A: epidemics & pandemics.
Type B: regional epidemics
Type C: sporadic cases & localized outbreaks.
☻Has 2 antigens projecting from its surface:
Haemagglutinin (HA)
Neuraminidase (NA)
16 known subtypes
9 known subtypes
Site of attachment to host Helps
releasing
newly
cells
formed viruses from host
cells
WHO nomenclature for influenza
 Strain type (A, B or C) / Geographical origin /
Laboratory reference number/ year of
occurrence / (description of H&N antigens).
 For example; A/ Mississippi/1/85/ (H3N2)
Antigenic drift
Antigenic shift
of
Modification of HA & NA Replacement
proteins,
viral proteins → a new viral
mostly due to
variant of A subtype with
genetic
antibodies
against recombination of
previous strains are not human & animal
able to neutralize this new influenza viruses →
variant
→
regional a completely new A
subtype
→
outbreaks
&
annual
pandemic.
epidemics
Since 1918, the only 3 influenza A sub-types
known to cause human disease are: H1N1, H2N2
& H3N2. Other subtypes such as H5N1 are rare.
Since isolation of influenza virus in 1933,
antigenic shifts occurred 3 times: in 1957, 1968 &
1977 (causing pandemic every time).
•
 No cross immunity between different antigenic
strains.
Avian Influenza
 Current pandemic is caused by subtype H5N1.
Swine flu
 Type A influenza viruses (H1N1 subtype).
Resistance:
Killed at 70C,by
 Killed by heat& oxidizing alcohol, vinegar &
agents.
disinfectants.
Reservoir of infection:
 Human cases (typical or Birds (wild &
atypical)+ swine + avian
Exit:
Nasopharyngeal secretions
domestic) + pigs
 Nasopharyngeal
discharges,
lacrimal
discharges,
faeces & blood.
Human cases + pigs
Period of
infectivity:
 3-5 days from clinical
days
onset in adult.
 7
days
children.
in
1 day before up to 7
young
sick.
after
becoming
Modes of transmission
Seasonal influenza
1. Direct droplet.
2. Nasal inoculation after hand contamination with
virus.
3.Freshly
contaminated
articles
with
nasopharyngeal discharges.
4. Air borne: (droplet nuclei & infected dust).
Avian Influenza
1. ANIMAL TO ANIMAL INFECTION: direct
contact of susceptible animal to secretions (saliva,
nasopharyngeal, feces or blood) of infected
animals. Many different animals are infected
including ducks, chicken, pigs, whales, horses &
seals.
2. Animal to human infection: direct contact of
humans with infected poultry, its discharges &
feces.
Antigenic shift & the danger of
person to person transmission:
If a pig is infected with both human influenza A
virus & AI virus in the same time, mixing genes
(Re-assortment) occur →a new virus → able to
infect humans & spread from person to person
resulting in an influenza pandemic.
IP:
1-3 days
Susceptibility:
1. Age: all ages are susceptible.
2.Immunity:
 Type specific & Transient immunity.
 Recurrent attacks due to multiple
strains, genetic mutation & no cross
immunity between different strains.
3.Environment:
Cold, over-crowdness & ill ventilation.
International 7 days.
 High
Clinical Picture:
moderate or severe form.
 Acute fever, headache,
myalgia, prostration, back
sore
throat,
rhinorrhea & cough.
 Self
limited
disease
(recovery within 2-4 days).
Complications:
1. 2ry bacterial infection e.g.
bronchitis,
2. Children with salicylate
therapy ►Reye disease
(CNS & liver).
+
influenza-like
 Sub-clinical, mild,
pain,
fever
symptoms.
 Diarrhea, vomiting,
abdominal pain
& bleeding from
nose and gums.
 As seasonal human flu.
 Some
people
reported
vomiting.
have
diarrhea
+
Diagnosis of
Seasonal Influenza
Laboratory Diagnosis
1.Direct identification of viral antigen
nasopharyngeal cells by FA test or ELISA.
2. A rising titre of specific serum antibodies.
in
Diagnosis of
Swine Flu
Case classification:
•Possible case:
clinical +epidemiological criteria.
•Probable case:
clinical + epidemiological criteria + positive influenza rapid
testing.
•Confirmed case: laboratory confirmation
Clinical criteria: one of the following:
1. Fever >38°C OR history of fever AND flu-like
illness (≥2 of the following symptoms: cough,
headache, rhinorrhea or vomiting/diarrhea).
2. Severe/life-threatening illness .
•Epidemiological criteria:
•At least one of the following in a person during the 7
days before onset of illness:
1. Close contact with a confirmed or probable
case of swine flu A (H1 N1) virus infection.
2. Traveled to a geographical area known to have
confirmed cases of swine influenza A/H1 N1
Prevention & Control
Prevention:
General:
Specific:
A. Active
immunization:
1. Inactivated trivalent
vaccine:
Prevention +
Control:
Prevention:
A. General
A. General
1. General
1. HE of public:
measures of
 Wash your hands.
prevention for
droplet &
 Avoid touching your
contact
eyes, nose or mouth
infections.
Nature :
Killed
containing
2
subtypes of A virus (H1N1 2. Measures for
& H3N2), B strain (currently patients with AI:
circulating strains present in
a.
the locality).
Isolation:
☻Efficacy: 80%
fever
 reduce complications by
with
60% & death by 80 %.
in
hospital
Avoid
touching
surfaces
contaminated
with
virus.
standard Healthy habits during
precautions.
cough & sneezing.
b.
Nursing
2. Measures for swine:
precautions: hand
☻ Dose:
 2 doses 0.5 ml I.M. for hygiene, gloves, gowns, 
eye
protection,
children not immunized disposable
blood
pressure
cuffs,
before.
thermometers, etc.
 Single dose if immunized
c. Tamiflu: anti viral
before.

drug of choice.
☻ Indications:
3.
1. Old aged persons > 65
years
2. Chronic
Measures
HCWs:
for
Standard
precautions,
numbers of infected &
potentially
infected
animals.
Quarantine:
infected
vaccination to ↓ risk of
3. HCWs.
co-infection
4. Immunosuppressed.
human & avian strain.
with
putting
farms
in
quarantine.
 Cook
debilitating surveillance,
diseases.
Culling: killing large
pork
thoroughly.
 Avoid
markets.
live
animal
2. LA intranasal vaccine:
 2 subtypes A&B
 Heat sensitive vaccine.
4. Measures during
food preparation
especially poultry:
B. Specific
prevention
Vaccination
of at risk
groups e.g.
Indication: only for healthy
b. Hand washing
people aged 5–49 ys.
with soap & water pilgrims.
 0.5 ml intranasal.
a.
 Produces local & systemic Handling
poultry.
immunity.
Hygienic
of raw
after
handling
or
raw
1. Admantadine HCL: frozen
adults
200
mg chicken or eggs.
(children100 mg) orally
c. Cook all poultry
for 10 days.
& products to a
2. Remantadine HCL: for high temperature >
70.
influenza A but not B.
B. Chemoprophylaxis:
 Side effects: fever & CNS
(5-10 % of cases).
d. Eggs should not
be
consumed
raw or partially
cooked.
 Contraindicated in patient
with psychological or
neurological disorders.
5. LAV given to poultry.
Control of
Seasonal Flu
I. Case:
 Treatment: Antibiotics + Antiviral
(Amantadine or Remantadine within 48 h of onset for 3-5 days).
II. Contacts:
Surveillance for IP.
Chemoprophylaxis.
III. Epidemic measures:
1. HE of the public, particularly high risk groups.
2. Immunization for high risk groups.
3. Surveillance of the community.
4. Adequate supplies of antiviral drugs & vaccination.
Control of
Swine Flu
I. Case:
 Notification to WHO.
 Treatment: Tamiflu
II. Contacts:
 Surveillance for maximum IP.
 Chemoprophylaxis.
III. Epidemic measures:
1. Locally organized immunization programs for high risk
groups.
2. Surveillance.
3. HE through media:
about mode of transmission + prevention.
MOH plan for flu pandemic, 2007
1. Database of all available health care settings.
2. ↑ number & quality of Labs for diagnosis of H1 N1virus.
3. HE of individuals, HCWs about signs , symptoms &
prevention.
4. Vaccination of HCWs with seasonal flu vaccine.
5. Provision of a strategic store of Antiviral drugs.
6. Provision of a strategic store of PPE e.g. masks.
7. Quarantine measures & sentinel surveillance e.g. at
airports & fever hospitals.
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