Throughout most of human history, the human population has been increasing. However, population has not always been steady and uninterrupted. For example, during the mid-1400s, there was a sharp decline in population as a result of the bubonic plague, or Black Death, that struck much of Europe and Asia. The plague killed more people than any other single disease; it claimed the lives of25 percent of the adult population of Central Europe and Asia. The population of England was reduced by about 50 percent between 1348 and 1379. In addition to the plague, worldwide outbreaks of cholera, typhus, malaria, yellow fever and smallpox have claimed millions of lives. The more densely population cities became, the more quickly diseases spread.

The biomedical revolution of the 20th century has also resulted in increased population growth. During this revolution, the death rates continued to drop as health and hygiene improved. The discovery of antibiotics and vaccines has wiped out or controlled many life threatening diseases. At the same time, birth rates have increased due to better prenatal care.

Population and Disease Outbreak

  1. During 1918 how did they flatten the curve for the Spanish Flu? Was there a secondary wave?
  2. What were the infection to death rates for the Spanish Flu like? Is this similar to Covid-19?  Can it be used as a template?
  3. “There’s a strong correlation between the risk of pandemic and human population density”… explain this in terms of density dependant and density independent factors for human populations. What is in our control to change?
  4. What is RO and how does that play into being able to make predictions about number of cases and immunity?

Ecological Change as a Cause of Disease Outbreaks?

Scientists know that the transmission of many infectious diseases is affected by climatic factors: temperature, humidity, surface water, wind, soil moisture and charges in forest distribution. Disease like malaria are especially influenced by changes in these factors, since they require an intermediate organism like a mosquito to transmit the actual disease. It is predicted that climate change altered weather patterns would affect range (latitude and altitude), intensity and seasonality of many infectious diseases. In general, increased warmth and moisture would enhance the transmission of these diseases.

  1. Explain the relationship between infectious disease and climatic factors.
  2. What specific aspect of climate change would affect the intensity, range and seasonality of diseases transmitted by carriers (mosquitos, flies, etc.) and can bats now be included?
  3. Considering an increase in temperature and precipitation to be the most evident direct affect of climate change, what will probably happen to the geographic distribution of diseases spread by mosquitos? Why? What evidence do we have for this?
  4. What does urbanization have to do with this?