1996 An infectious tumor was found in the northeast corner of Tasmania. By 5438+0 in 2006, Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians Tasmanians will lose their lives after six months of infection. At present, there is only one infectious cancer we know: canine infectious reproductive tract tumor, which appeared 10 thousand years ago. In the process of dog sexual intercourse, if one party suffers from this tumor, cancer cells will metastasize.
Usually, cancer occurs and ends in individuals, and there are several barriers to prevent cancer from migrating between different individuals. The whole process of cell transfer from one person to another must be completed in a short time. In vitro, cells are difficult to survive, and will dry up and die after leaving the human body for a few minutes. In order to successfully metastasize, cancer cells must be in direct contact with the living tissue of the new host. After cancer cells enter Shinjuku, they will need to escape immune recognition. The immune system of higher organisms (such as humans) has a series of mechanisms to detect and destroy foreign cells. Different creatures will have unique protein fragments. When a new host finds foreign cells with these signals, it will launch a fierce attack until it is removed. Some biologists believe that this gene is so diverse that cancer will not be spread.
However, Tasmanian devils just lack such a genetic barrier. Under the influence of many factors, cancer spread rapidly among races, making them almost extinct.
So will this infectious tumor threaten human beings? Human genetic diversity is extremely rich, which can ensure that a strong immune response kills invading cells, and the bitten person will not get sick and will not transmit the tumor to others. However, some experts believe that human beings should not sit back and relax. Nowadays, with the rapid growth of population, HIV infects millions of people and destroys their immune systems, resulting in many cancers that were rare in the past. This situation is conducive to the evolution of infectious tumors. Infectious tumors appear in people with suppressed immune function, and then evolve the ability to infect ordinary people. This possibility is absolute.
So will cancer be transmitted to people now? Scientists have made bold experiments. 195 1 year, a man named Harriet? An American in Los Angeles died of cervical cancer. After her death, cancer cells were extracted and cultured in vitro for medical research. These cells extracted from her are also called Hella cells. Southam, a medical scientist, learned that injecting Hella cells into mice would make them suffer from cancer. How about injecting Hela cells into human body?
Driven by curiosity, Southam found a leukemia patient, injected normal saline mixed with millions of HeLa cells into the patient, and then he found more than a dozen patients to inject HeLa cells. A few days later, the patient's arm appeared red and swollen lumps, that is, malignant tumors, but gradually subsided after one month. However, one of these patients died because of the spread of cancer cells, but these people who were tested themselves had cancer, which does not mean that injecting cancer cells will lead to cancer.
Solan intends to do experiments with healthy people. He recruited 65 able-bodied men from prisons in Ohio and injected HeLa cells several times in a few months. As a result, all prisoners rely on their own immune system to defeat foreign cancer cells. Moreover, each injection, the shorter the swelling time, these people have developed drug resistance.
Human cancer cells will not be infected by injection, and heterogeneous cancer cells are easily detected and destroyed by the immune system. Just like patients who need organ transplantation need to be matched, otherwise rejection will lead to organ failure and death. Even if the matching is successful, patients should take drugs for life to reduce rejection.
Although human cancer is directly contagious, it is indirectly contagious.
Hepatitis B virus-liver cancer
China is a big country with liver cancer, and half of the patients and deaths of liver cancer in the world are in China. The reason is that hepatitis B virus has spread rapidly in China for 30 years. At that time, about 1 people in China carried hepatitis B virus. Hepatitis B virus can be transmitted through blood, mother to child and sex, leading to the emergence of many "liver cancer families". Hepatitis B virus is the main cause of liver cancer in China. Some patients with hepatitis B virus will develop cirrhosis and some will develop liver cancer. The probability is about 1%. The best way to prevent hepatitis B virus is to get hepatitis B vaccine, so that it is not easy to be infected by hepatitis B after producing antibodies.
Human papillomavirus
There are many types of human papillomavirus, which can cause common warts, genital warts and various sexually transmitted diseases, as well as anal cancer, prostate cancer, bladder cancer, cervical cancer, rectal cancer, oral cancer and tonsil cancer. The main infection modes are blood transmission, mother-to-child transmission, sexual transmission and iatrogenic infection. At present, there are cervical cancer vaccines that can prevent some types of human papillomavirus infection, including most types of human papillomavirus that may cause cervical cancer.
Hewlett Packard
Helicobacter pylori (HP) is the chief culprit of many kinds of stomach diseases. The incidence of gastric cancer in China is very high, and 40% of patients with gastric cancer in the world are in China. According to the World Health Organization, 78% of gastric cancer can be attributed to chronic infection of Helicobacter pylori. Helicobacter pylori mainly comes from mouth-to-mouth transmission between people. People infected with Helicobacter pylori eat together and use tableware for a long time, which is easy to be infected. Family-style dinner in China is a good way of transmission, so family-style gathering of Helicobacter pylori often occurs. In addition to not eating with infected people, we should also pay attention to improving the resistance of the stomach and preventing Helicobacter pylori.
The occurrence of cancer is composed of many complicated factors. In addition to genetic susceptibility, so-called "marital cancer" and "family cancer" often have the same bad habits. Cancer itself is not contagious, but bad living habits can. # Breeze Plan # # Healthy Life I See ##39 Healthy Super Group #
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