Table 1.

Major Indices of Malaria Transmission: Advantages and Disadvantages

Index	What is Measured	Advantages	Disadvantages
Entomological Inoculation Rate (EIR)	Infectious bites per unit time (usually per year)	Direct reflection of vector control and antigametocytocidal drugs	- No standard protocols - Variability in methodologies - Few trained specialists
Parasite Rate (PR)	Proportion of the population found to carry asexual parasites in RBCs; can also assess gametocyte rates; by age group	Direct reflection of inoculations, immunity, and treatment effectiveness in humans	- Microscopy "gold standard"; lacks sensitivity - Prone to technical efforts - Changes may occur following environmental and control factors
Annual Parasite Index (API)	Number of parasite infections in a well-defined geographical area; usually per 1,000 persons per year	Direct reflection of all prevention and control effects on humans	- Depends on active case detection system, which is often poor
Spleen Rate (SR)	Proportion of children 2-9 years of age with a palpable spleen	Non-invasive, indirect way of measuring impact of malaria on spleen	- Variability in examiners; many causes of splenomegaly - Point prevalence measurements can vary/change rapidly