The attack rate is a crucial epidemiological measure used to describe the proportion of a population that becomes ill with a specific disease during a specific period. It is particularly useful for characterizing the risk of developing a disease among those who have been exposed to a particular risk factor or within a defined population group.
The formula for attack rate is straightforward:
Attack Rate = (Number of Cases / Total Exposed Population) * 100
The result is typically expressed as a percentage, indicating the likelihood of an exposed individual contracting the disease. A higher attack rate suggests a more potent or easily transmissible agent, or a more susceptible population.
For example, if a new virus spreads through a company picnic, and 500 people attended (the exposed population), and 75 of them subsequently became ill with the virus, the attack rate would be calculated to understand the disease's impact within that specific group. This data helps public health officials assess the severity of an outbreak and implement appropriate control measures.
function calculateAttackRate() {
var exposedPopulation = parseFloat(document.getElementById("exposedPopulation").value);
var numberInfected = parseFloat(document.getElementById("numberInfected").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(exposedPopulation) || isNaN(numberInfected)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (exposedPopulation <= 0) {
resultDiv.innerHTML = "Total Exposed Population must be greater than zero.";
return;
}
if (numberInfected exposedPopulation) {
resultDiv.innerHTML = "Number of Infected Cases cannot be greater than the Total Exposed Population.";
return;
}
var attackRate = (numberInfected / exposedPopulation) * 100;
resultDiv.innerHTML = "