Scientists have engaged themselves in deep study and research on the disease causing organisms. In the beginning of 17th century, a group of scientists made a huge step in analyzing some of the disease causing micro organisms in both animals and human body. Research carried out gave the discovery of the major disease causing organisms and the scientists identified them as viruses. The discovery was enhanced by the need to look for a solution to small pox, a disease that was claiming lives of large number of children. Edward Jenner led the research which led to a great breakthrough when a vaccine for small pox was developed. With extensive research being carried out by medical experts, other infectious organisms have been found some which resemble viruses in their mode of causing diseases. Some of the resent discovered infectious organisms are viroids and Prions.
Viruses invade cell nuclei where they develop to maturity and reproduce. Inside the cell, the virus takes control of the chemical reactions taking place inhibiting the production of proteins by the attacked cell. The cell instead is diverted to the production of viral proteins which favor the making of new virus in the cell. With time the cell grows weak because of the inhibited production of important materials like proteins that help it survive. The cell now operates under instructions from the invading virus hence unable to catty out its functions properly.
According to Getty (2003), some viruses attack the cells by inserting their genetic material into the attacked cell specifically putting the materials in the DNA of the cell. The materials now take control of the activities taking place in the cell once they invade the DNA of the host cell (Robertson, 2006). The first effect noted is the direct copying of their genes interfering with the message in the cell. The cell finally becomes directed by the information found in the genetic material of the invading cell.
Although medical experts have referred virus as the tiniest infectious things, enhanced medical research has been carried and identified other tiny things that cause infections. One of those tiny infectious things is the viroids. Some medical experts have described them as a version of the normal viruses. The tiny organisms are known to cause diseases in animals and human beings. Their structure varies from that of viruses. The tiny organisms have been connected to most of the crop diseases according to the extensive agricultural research done over the years. The organisms attack crops and cause problems especially on tomatoes and some fruit producing trees. Viroids have a unique internal structure because they do not contain DNA like viruses. Viroids contain RNA only which lacks a caspid and an envelope. According to recent medical research carried out, viroids have also been connected to hepatitis D (Clark, 2007).
Prions are other infectious micro organisms that attack both human beings and animals. The organisms have been connected with brain disase in animals an example of the Mad Cow Disease. The organisms invade the brain of animals and the brain appears holey making it ineffective. In human beings, the organisms also cause brain diseases and the brain of the affected person malfunctions once in a while due to the effect of Prions. According to Betal (2006), Prions are neither DNA nor RNA in their structure. The microorganisms are just proteins which may be wrongly placed in the body of animals and human beings therefore causing diseases.