Presented By:

Dr.Md.Salequr Rahman

Dep. of Community Medicine

Oxford Text book of public health “ It is the relative protection of a population group achieved by reducing or breaking the chains of transmission of an infectious agent because most of the population is resistant to infection through immunization or prior natural infection”

HERD STRUCTURE: (IT INCLUDES-)

Human population Animal reservoir or host Insect vector Environmental factors Social factors

CONCEPTS BEHIND HERD IMMUNITY

MACHANISOM:

Immunization of 70-80% people

Remainder 20-30% are either cases or susceptibles

Scanty number of primary cases

Frequency of secondary case development decreases

Eventually secondary case development becomes nil

Tansmission block of the disease

No disease

HOW HERD IMMUNITY CAN BE ACHIEVED:

Immunization Clinical & sub-clinical

infection Elimination of insect

vector Elimination of animal

reservoir Provision of safe water

supply Provision of sanitary

disposal of fefuse & sewage

Provision of proper nutrition

FACTORS THAT AFFECT HERD IMMUNITY:

A. Demographic : large number of births how are not prooerly immunized

B. Health care facilitiesC. Social & political factors

War CycloneFamineEconomic disruption