Correct Option
The correct option is Susceptibility of a population to illness
Explanation
In the assessment of public health and infrastructure, indicators are broadly classified into mortality (related to death) and morbidity (related to disease and illness). While mortality rates track the frequency of deaths, morbidity rates track the frequency of illness within a population.
Option Analysis
- Increase in average life expectancy is Incorrect. The increase in life expectancy is a measure of longevity and overall health outcomes, not specifically the incidence of disease (morbidity).
- Susceptibility of a population to illness is Correct. Morbidity is defined as the state of being unhealthy or the incidence of disease. In the context of health infrastructure, it refers to the population's proneness to fall ill. High morbidity indicates a high prevalence of disease, which is directly linked to the lack of preventive infrastructure such as potable water, sanitation, and hygiene.
- Rate of deaths within a population is Incorrect. The death of infants is measured by the Infant Mortality Rate (IMR), which is a mortality indicator, not a morbidity indicator.
- Availability of medical personnel is Incorrect. The number of doctors per 1000 population is a measure of health workforce density or human resources in health, not a measure of the population's disease burden.
Key Takeaway
Morbidity refers to the prevalence of illness or disease in a population, whereas Mortality refers to the incidence of death.