Public Health Approaches to Infectious Disease

# 3.1 Primary prevention strategies

Public health strategies aimed at the primary prevention of infectious disease seek to prevent new cases of infection from occurring by interrupting the transmission of pathogens to susceptible human hosts, or increasing their resistance to infection.

Vaccination operates at the level of primary prevention:

- directly, by increasing the resistance of the uninfected population to the pathogens from which the vaccine was prepared
- indirectly, by decreasing exposure to pathogens, because it reduces the proportion of infected individuals in the community who could transmit the infection to its unvaccinated members.

This protective effect is known as herd immunity, and the herd immunity level is reached when the ratio of immune-to-non-immune individuals is high enough to stop the infection circulating in the population because there are so few susceptible individuals.

Educating mothers about the benefits of breast feeding their babies exclusively for the first six months is another example of a primary prevention strategy. Breast feeding is promoted not only for its nutritional benefits but also to protect breast-fed infants against the pathogens that can contaminate feeding bottles, animal milk and infant formula prepared with unsafe water. Breast milk also contains maternal antibodies, so it provides babies with passive immunity against enteric pathogens.

Suggest some other examples of public health interventions aimed at the primary prevention of infectious disease.

## Answer

You might have thought of many other examples in addition to our suggestions below.

- Distribution of free condoms in areas of high HIV prevalence, coupled with ‘safer sex’ education about sexually transmitted infections (STIs).
- Food safety legislation, inspection of catering premises and slaughterhouses, and education about hygienic food-handling practices to prevent outbreaks of food poisoning.
- Training community members to drain mosquito breeding sites near homes in endemic malaria areas, and distributing ITNs to cover beds at night.
- Education of community members who lack access to safe sources of water so that they know they should boil unsafe water before using it for drinking, cooking or mixing formula feeds for infants.

You will see as this course progresses that many other examples of public health interventions operate at the primary prevention level.

OpenLearn - Public Health Approaches to Infectious Disease
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