viral droplet infections dr. abd el hamied mohamed abd el hamied lecturer of occupational health...

Viral Droplet InfectionsDr. 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 disease characterized by fever, general & catarrhal manifestations.

Infectious viral disease of birds. Some (AI) viruses can cause infections (clinical or subclinical) in humans.

Acute infection caused by Type A influenza viruses (H1N1 subtype).

Public health significance:

Seasonal influenzaOccurs 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 Influenza1st 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 agepregnant 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 influenzaType A: epidemics & pandemics. Type B: regional epidemicsType C: sporadic cases & localized outbreaks.

☻Has 2 antigens projecting from its surface:

Haemagglutinin (HA) Neuraminidase (NA)16 known subtypes 9 known subtypesSite of attachment to host cells

Helps releasing newly 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 shiftModification of HA & NA

viral proteins → a new variant of A subtype with antibodies against previous strains are not able to neutralize this new variant → regional outbreaks & annual epidemics

Replacement of viral proteins, mostly due to genetic recombination of human & animal influenza viruses → a completely new A subtype → pandemic.

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 by heat& oxidizing

agents.

Killed at 70C,by

alcohol, vinegar &

disinfectants.

Reservoir of infection: Human cases (typical or

atypical)+ swine + avian

Birds (wild &

domestic) + pigs

Human cases + pigs

Exit: Nasopharyngeal secretions

Nasopharyngeal

discharges,

lacrimal

discharges,

faeces & blood.

Period of communicability: 3-5 days from clinical

onset in adult. 7 days in young

children.

1 day before symptoms

up to 7 or more days

after becoming sick.

Resistance: Killed by heat& oxidizing

agents.

Survives in low

temperature & water.

Killed at 70C,by

alcohol, vinegar &

disinfectants.

Reservoir of infection: Human cases (typical or

atypical)+ swine + avian

Birds (wild &

domestic) + pigs

Human cases + pigs

Exit: Nasopharyngeal secretions

Nasopharyngeal

discharges,

lacrimal

discharges,

faeces & blood.

Period of infectivity: 3-5 days from clinical

onset in adult. 7 days in young

children.

1 day before up to 7

days after becoming

sick.

Modes of transmission

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).

Seasonal influenza

Avian Influenza1. 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 International 7 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.

Clinical Picture: Sub-clinical, mild, moderate or severe form. Acute fever, headache, myalgia, prostration, back pain, sore throat, rhinorrhea & cough. Self limited disease (recovery within 2-4 days).

High fever + influenza-like symptoms.

Diarrhea, vomiting, abdominal pain & bleeding from nose and gums.

As seasonal human flu.

Some people have reported diarrhea + vomiting.

Complications:1. 2ry bacterial infection e.g.

bronchitis, 2. Children with salicylate therapy ►Reye disease (CNS & liver).

Diagnosis ofSeasonal Influenza

Laboratory Diagnosis

1.Direct identification of viral antigen in nasopharyngeal cells by FA test or ELISA.

2. A rising titre of specific serum antibodies.

Diagnosis ofSwine 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:

Nature:Killed containing 2 subtypes of A virus (H1N1 & H3N2), B strain (currently circulating strains present in the locality).

☻Efficacy: 80%

reduce complications by

60% & death by 80 %.

☻Dose: 2 doses 0.5 ml I.M. for

children not immunized

before. Single dose if immunized

before. Vaccine should be given

each year before season

of expected influenza.

☻Indications:1. Old aged persons above

65 years

2. Cases with chronic

debilitating diseases.

3. HCWs.

4. Immunosuppressed

children.

2. Live attenuated intranasal vaccine:

Formed of 2 subtypes

A&B Heat sensitive

vaccine. Given 0.5 ml by

intranasal spraying. Produces local &

systemic immunity.B.

Chemoprophylaxis: for

influenza A not B Admantadine HCL: 200

mg orally for 10 days for

adults & 100 mg for

children. Side effects: fever & CNS

(5-10 % of cases). Indications: high risk

groups as elderly,

children & chronic

disease. Contraindicated in patient

with psychological or

neurological disorders.

Prevention + Control:

1. General measures of prevention for droplet & contact infections.

2. Measures for patients with AI:

a. Isolation: in fever hospital with standard precautions.

Respiratory

precautions, hand

hygiene, gloves,

gowns, eye

protection,

disposable blood

pressure cuffs,

thermometers….etc

.

3.Measures for HCWs: Standard

precautions,

surveillance,

vaccination to

reduce risk of co-

infection with

human & avian

strain.

4. Precautions for food preparation especially poultry:

Raw poultry

should be handled

hygienically. Cook all poultry&

poultry products to

reach a high

temperature

above 70. Eggs should not

be consumed raw

or partially

cooked. Washing of hands

with soap + water

after handling

frozen or raw

chicken or eggs.

5. LAV given to

poultry.

6. Tamiflu: anti viral

drug of choice.

Prevention: A. General A. General

1. HE of public: Wash your hands.

Avoid touching your

eyes, nose or mouth

Avoid touching

surfaces

contaminated with

virus.

Healthy habits during

cough & sneezing.

Sanitary environment.Measures for swine: Culling: killing large

numbers of infected &

potentially infected

animals. Quarantine: putting

infected farms in

quarantine. Cook pork

thoroughly. Avoid live animal

markets, poultry and

pig farms in infected

countries.

B. Specific prevention

A recently developed

vaccine given for at

risk groups e.g.

pilgrims.




☻Nature:Killed

2 subtypes of A & B strains.

☻Efficacy: 80%


60% & death by 80 %.




before.

☻Indications:1. Old aged persons > 65

years

2. Chronic debilitating

diseases.

3. HCWs.

4. Immunosuppressed.

2. Live attenuated intranasal vaccine:

Formed of 2 subtypes

A&B Heat sensitive

vaccine. Given 0.5 ml by

intranasal spraying. Produces local &


Chemoprophylaxis: for

influenza A not B Admantadine HCL: 200


adults & 100 mg for

children. Side effects: fever & CNS


groups as elderly,

children & chronic






2. Isolation precautions for patients with avian flu:

b. Nursing precautions: hand hygiene, gloves, gowns, eye protection, disposable blood pressure cuffs, thermometers, etc.c. Tamiflu: anti viral drug of choice.

3. Measures for HCWs: Standard

precautions,

surveillance,

vaccination to ↓ risk of

co-infection with

human & avian strain.


Raw poultry

should be handled


poultry products to

reach a high

temperature


be consumed raw

or partially

cooked. Washing of hands

with soap + water

after handling

frozen or raw

chicken or eggs.

5. LAV given to

poultry.


drug of choice.

Prevention: A. General Prevention

1. HE of public: Wash your hands. Avoid touching your

eyes, nose or mouth.Avoid touching

surfaces

contaminated with

virus.Avoid contact with

sick people.Healthy habits during

cough & sneezing.

2. Measures for swine: Culling: killing large



animals.

Quarantine: putting

infected farms in

quarantine.

Cook pork

thoroughly.

Avoid live animal

markets.




risk groups e.g.

pilgrims.




☻Nature:Killed


☻Efficacy: 80%


60% & death by 80 %.




before.


65 years


diseases.

3. HCWs.


2. LA intranasal vaccine: 2 subtypes A&B Heat sensitive vaccine. 0.5 ml intranasal. Produces local & systemic

immunity.

Indication: only for healthy

people aged 5–49 ys.

B. Chemoprophylaxis: 1. Admantadine HCL: adults 200 mg (children100 mg) orally for 10 days.

2. Remantadine HCL: for influenza A but not B.

Side effects: fever & CNS


groups as elderly,

children & chronic







Respiratory,hand,

gloves, gowns, eye

protection,

disposable cuffs,

thermometers….etc


precautions,

surveillance,

vaccination to

reduce risk of co-

infection with

human & avian

strain.

4. Measures during food preparation especially poultry: a. Hygienic Handling of raw poultry. b. Hand washing with soap & water after handling frozen or raw chicken or eggs. c. Cook all poultry & products to a high temperature > 70.

Washing of hands

with soap + water

after handling

frozen or raw

chicken or eggs.

5. LAV given to

poultry.


drug of choice.

Prevention: A. General



surfaces

contaminated with



cough & sneezing.

2. Sanitary environment.





infected farms in



markets.


Vaccination of at risk groups e.g. pilgrims.




☻Nature:Killed


☻Efficacy: 80%


60% & death by 80 %.




before.


65 years


diseases.

3. HCWs.


2. LA intranasal vaccine: 2 subtypes A&B Heat sensitive

vaccine. 0.5 ml intranasal. Produces local &


Chemoprophylaxis:

For influenza A not B Admantadine HCL: 200


adults & 100 mg for

children.

Side effects: fever & CNS (5-10 % of cases).

Contraindicated in patient with psychological or





Respiratory,hand,

gloves, gowns, eye

protection,

disposable cuffs,

thermometers….etc


precautions,

surveillance,

vaccination to

reduce risk of co-

infection with

human & avian

strain.


Raw poultry

should be handled


poultry products to

reach a high

temperature


be consumed raw

or partially

cooked.

d. Eggs should not be consumed raw or partially cooked.

5. LAV given to poultry.

Prevention: A. General



surfaces

contaminated with



cough & sneezing.

2. Sanitary environment.





infected farms in



markets.




risk groups e.g.

pilgrims.

Control ofSeasonal 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 ofSwine 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, 20071. 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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viral droplet infections dr. abd el hamied mohamed abd el hamied lecturer of occupational health...

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