Small pox

Presented by: Sulov SahaMd.Mehedi Hasan

Klinton AliShuvasish Paul

# Caused by Variola virus

# Double stranded DNA virus

# Genus: Orthopoxvirus

# Variola major or minor

# Stable outside host(retains infectivity)

The Organism

Variola major– Classic smallpox– Predominant form in Asian epidemics– Highest mortality (~30%)

Variola minor– Causes milder disease

– Discovered in 20th century– Started in S. Africa

– Was most predominant form in N. America

Microbiology

All ages and genders affectedIncubation period • From infection to onset of

prodrome• Range 7-17 daysMortality• 30% overall in unvaccinated

population• Infants, elderly greatest risk

(>40%)• Dependent on virus strain• Dependent on disease variant

Microbiology continues

No animal reservoir and no human carriers.

First certain evidence comes from the mummified remains of Ramses(1157 B.C.).

First Case of Smallpox

Pathophysiology

Virus lands on respiratory/oral mucosa

Macrophages carry to regional nodes

Invades reticuloendothelial organs

White Blood Cells infected

Systemic inflammatory response

Stages of Smallpox

Three stages of disease:• 1. Incubation

• Asymptomatic• 2. Prodromal

• Nonspecific febrile illness, flu-like• 3. Eruptive

• Characteristic rash

Clinical feature Rash Stages of Development

Clinical feature Host Genes Expressed During Smallpox

• The first symptoms of smallpox usually appear 12 to 14 days after you're infected.

• During the incubation period of seven to 17 days, you look and feel healthy and can't infect others.

Symptoms & Signs

Symptoms

•Initially via aerosol•Then person-to-person•Hospital outbreaks from coughing patients•Highly infectious

Airborne route

Infectious Materials:

Saliva

Vesicular fluid

Scabs

Urine

Conjunctival fluid

Possibly blood

Transmission

• Physical examination and blood tests. Fever and the distinctive, progressive skin rash will indicate smallpox.

• Smallpox and monkeypox virions may be indistinguishable.

Diagnosis

• The smallpox vaccine is the only known way to prevent smallpox in an exposed person. The smallpox vaccine helps the body develop immunity to smallpox.

Prevention

Variolation

• Inoculation with infectious smallpox • Scabs or pustular material

• 3% mortality• Immunized were infectious - outbreaks• Provided full immunity• Originated in Eastern countries in ancient times• Started in U.S. by Rev. Cotton Mather 1721

Treatment

VaccinationEdwar

d Jenner develo

ps vaccin

e

1796

Freeze-dying technology

1940’s

Licensure of bifurcated

needle

1965

Attenuated strains1975

Vaccine removed from civilian market

1983

Vaccine Administration

Jet gun• Rapid• High

maintenanceBifurcated

needle • High

efficacy, sterilizable, rapid (1500/day)

• Uses less vaccine

• Mainstay for the WHO eradication campaign

Smallpox (Vaccinia) Vaccine Dryvax®• Lyophilized vaccinia containing calf

lymph.• Trace amounts of antibiotics:

• Polymyxin B.• Streptomycin.• Chlortetracycline.• Neomycin.

Smallpox Vaccine

Complications of Vaccination

Treatments for Complications:

1. Vaccinia Immune

Globulin(VIG)

2. Cidofovir

Eczema vaccinatum Progressive vaccinia

Generalized vaccinia Post-vaccinial encephalitis

•Exposure to a case patient after fever onset•Contact with secretions or•Face-to-face contact or•In nosocomial setting with a case•Includes all hospital patients and staff

Carefully

identify

true contacts:-

Management of Case Contacts

Fig: Ring vaccination

Outbreak Management

Case

Contact to Case

Contact to Contact

Strategy in

outbreak

•All confirmed or suspected cases•All contacts of confirmed/suspected cases•All hospital personnel of hospitalized cases•All other patients in hospital with cases

WHO Smallpox Eradication Campaign Begins

Campaign Continues

• Oct 26, 1977, last case of smallpox.• May 8, 1980, official declaration by WHO - Smallpox

Eradicated!

The End of Smallpox

Last case of Variola minor, Somalia 1977

Last case of Variola major, Bangladesh 1975

Slow spread

Effective, relatively

safe vaccine

No animal/insect vectors

Infectious only with symptoms

Prior infection gives lifelong

immunity

International cooperation

Factors That Allowed Smallpox Eradication

Variola viruses do not exist in

nature.

Some nations are suspected of having active bioweapons programs.

North Korea

Syria

Iran

Israel

Russia

Some may have kept smallpox stocks hidden.

The world is ill-prepared for

smallpox.

Vaccination is no longer routine.

Thus, a large susceptible population.

Smallpox as a Biological Weapon

Thanks