Delta Pronunciation: (del-ta). Delta letter quick facts. Delta is the fourth letter (Greek letter #4) in the modern day Greek alphabet. The Delta letter appears before Greek letter Epsilon which is pronounced (ep-si-lon), and after the letter Gamma which is pronounced (gam-ah). Delta Letter Template size: 600 X 600 pixels. Greek letter set: #1 to #12 (12 color combinations).
The most common disease-causing agents are viruses, bacteria, protozoa, and parasitic worms. Viruses are not living, but do get transferred between living organisms. The West Nile Virus is transferred from mosquitoes to humans. Vaccines are a good way to prevent the spread of viruses.iruses are the disease-causing agent that most people are familiar with. They cause colds, the flu, HIV, meningitis, polio, chicken pox, rabies, West Nile, and a number of other diseases. Viruses themselves aren't living things, but they do get transmitted between living organisms.
Viruses were filtered through these and called âfilterableâ organisms. Loeffler and Frosch (1898) reported that the infectious agent of foot and mouth diseases virus was a filterable agent. In 1900 first human disease shown to be caused by a filterable agent was Yellow Fever by Walter Reed.irology â the study of viruses. The study of viruses is called virology. Experiments on virology began with the experiments of Jenner in 1798. Jenner did not know the cause but found that that individuals exposed to cow pox did not suffer from small pox.