There are a number of tools for measurement or description in epidemiology. These include:
Prevalence: frequency of a disease at a particular time. Based on prevalence a disease may be defined as endemic (maintain a relatively constant but moderate level of occurrence), Hyper- endemic (persistently high and continuous level of occurrence), epidemic (an outbreak or sudden occurrence of a disease with considerable intensity) or Holoendemic ( high prevalence amongst children in a population).
Epidemiological rate- morbidity rate, mortality rate, incidence rate, admission rate etc. Disease Burden (overall weight of effect of a disease) using DALY.
Estimation of disease intensity using direct parasite count, indirect counting of eggs and cysts in faeces, indirect measurement of levels of immunological responses to parasite antigens.
Parasite dispersion estimation which may be under dispersion, random or over dispersion. Geographical distribution estimation using mapping techniques such as manual cartographic maps, geographic information system and remote sensing.
Epidemiological studies may be descriptive, analytical (cohort, or case control), experimental or rapid epidemiological assessment.
Disability Adjusted Life Years (DALYs)
In epidemiology, the disease burden on the economy is approached from the view that morbidity from parasitic infection impairs productivity as a result of loss of valuable man- hour. This is calculated using an index known as the Disability adjusted life years (DALYs).
DALYs is an health indicator which translates disabilities into years of healthy life lost, by giving each disease state a disability weight ranging from zero (healthy) to 1 (death). It incorporates the potential years of lost life as a result of death at a given age. It measures the burden of a disease of a defined population and the effectiveness of interventions. They are valid indicators of population heath.
In summary, DALYs can simply be defined as the number of health years of life lost due to premature death or disability.