3. 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”
4.
5. HERD STRUCTURE: (IT INCLUDES-)
Human population
Animal reservoir or host
Insect vector
Environmental factors
Social factors
14. 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
16. 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
17.
18. FACTORS THAT AFFECT HERD IMMUNITY:
A. Demographic : large number
of births how are not prooerly
immunized
B. Health care facilities
C. Social & political factors
War
Cyclone
Famine
Economic disruption