On March 26, 2020, Professor Ora Paltiel, of Hebrew University’s School of Public Health and the Department of Hematology, presented “Epidemiology: It’s Not Only About Epidemics” as part of HU’s second series of webinars on the coronavirus pandemic. Early in her talk, she explained epidemiology isn’t just about infectious diseases but also chronic illnesses such as heart disease and cancer.
Prof. Paltiel gave some historical background, citing the father of modern epidemiology who was a 19th century physician in England named John Snow who traced the source of a cholera epidemic in London in 1854. He was the first to suspect water was the culprit while others insisted it was air-based. The medical community initially rejected Snow’s findings which later led to changes in the city’s water and waste systems and a major improvement in general public health.
According to Prof. Paltiel, who holds a Master’s Degree in epidemiology and biostatistics and has devoted much of her research to cancer epidemiology, an epidemic is an incidence of disease greater than expected. Epidemics go up and down. Endemics, such as malaria, are when every month you get a certain number of cases with no major spikes. A pandemic is a global distribution of an epidemic, such as H1N1 (Swine Flu) or the Spanish Flu. Most pandemics result from viruses jumping from animals to humans. As virulent as COVID-19 now seems, it’s not the worst pandemic humanity has suffered, she said, nor will it be the last.
Prof. Paltiel outlined the steps that an epidemiological team takes when investigating a disease, including establishing a first definition based on a viral genome, followed by a second one based on CT scans. Other important factors in assessing the severity of an epidemic or pandemic is measuring the coverage and rate of infection, case fatality rates and other elements in the web of causation and interaction of various risk factors. It’s critical that the data be accurate, which is sometimes difficult.
To view the slides from Prof. Paltiel’s webinar, see below.