Although bacteria were until recently seen by most people as harmful to health, increased research on our gut micriobiome made clear that there are many benevolent bacteria on which our health depends and that the use of antibiotics has the potential to carry significant harmful consequences as a result. Far less people realize however, that like bacteria, viruses are also capable of aiding our health, including some of the viruses that no longer infect us as a consequence of vaccination.
The best example to begin with of a benevolent virus would probably be Adenovirus-36. Adenovirus-36 is suspected of causing obesity. Some people now suggest vaccinating against Adenovirus-36 as a solution to the obesity crisis. This would be a bad idea however. More than half the adult population in the United States now suffers either diabetes or prediabetes.
Ad36 however has been shown to have a strong effect on insulin resistance. In an overweight group of study subjects, diabetes was practically non-existent in the minority of subjects who were Ad36 positive, as a consequence of the ability of the virus to increase insulin sensitivity by promoting lipogenesis. Lipogenesis is the process by which the body converts simple sugars into fat, which is important to protect our blood vessels against the consequences of glucose peaks.
Since the virus only increases the conversion of excessive simple sugar intake, it’s clear that the virus is not malignant. It does not cause someone who has a healthy diet to develop obesity, as a healthy diet would not lead to frequent blood glucose peaks. Rather the virus improves the body’s natural coping mechanism in response to a poor diet.
Evidence also exists that suggests that some viruses that are sexually transmitted are important to human health. Cytomegalovirus is a nearly ubiquitous herpes virus, that is known to lead to certain harmful conditions. It was until recently unclear why this virus is so common, but recent studies suggest that Cytomegalovirus actually plays an important role in addressing influenza infections. Young mice infected with CMV were strongly protected against an influenza virus challenge in experimental studies.
An interesting question then becomes to ponder what sort of effect influenza has on our body. Scientists have long attempted to link influenza to lung cancer, but the evidence was controversial. Tissue abnormalities that were seen as pre-cancerous stages were later thought to be part of a normal bodily response to address influenza infection.
Interesting to note however, is that some of these studies actually found that influenza infection prohibits the development of cancer. One study found that influenza prevented both spontaneous and experimentally induced adenoma development in mice.
An earlier study done in 1940 also sought to prove that influenza infection causes lung cancer. Instead, the authors concluded that the opposite must probably be true. Age at which tumors occurred and the number of mice with tumors was much lower in an influenza infected group, and section of the lungs infected with influenza had less tumors.
Of course, more recent research would be interesting, but oftentimes, research into this subject dries up when the benevolent effects of a virus are discovered, as eradication through vaccine development, which initially stimulates such research, become uninteresting as a result when we find that the viruses protect against cancer or have other beneficial effects.
Unfortunately, we tend to be drawn the wrong conclusion, when we find that viral infection is associated with certain conditions. In many cases, it appears that despite being more prevalent in animals suffering a particular condition, the virus actually has a benevolent effect on the condition. A recent example of this problem is the case of Lupus.
Lupus in humans is generally associated with Epstein Barr virus activity, so scientists decided to study mice, to find out whether a related virus used as a model for Epstein Barr in mice has an effect on Lupus. It was found that the virus, gammahervesvirus 68, actually significantly reduces the risk of autoimmunity development in mice. Rather, the virus significantly reduced both tissue damage and the production of antibodies associated with Lupus.
Sexually transmitted diseases have an interest in not harming their host, because for them to reproduce, their host has to remain healthy enough to have sex with other potential carriers. Viruses that are harmful at first would thus be expected to become less harmful over time as they pass through successive hosts. HIV is an example of such a virus that’s harmful because it’s novel. Luckily, other sexually transmitted viruses exist that greatly reduce the harm done by HIV. One such virus, GB virus C, was found to reduce the risk of death by 59% in HIV positive people.
Our war on viruses in the form of vaccination may ultimately come to cost us dearly, because many of the viruses we are in the process of eradicating are likely a net benefit for our population. A natural infection with the measles virus has the ability to preferentially destroy cancer cells. We also understand the causative mechanism behind this.
Natural infection with the mumps virus was associated in one study with a 19% reduced risk of Ovarian cancer.  A second study found a 28% reduced risk.  The reason is because ovarian cancer cells express higher amounts of MUC1, which the body forms antibodies against after mumps infection. Breast cancer and uterine cancer cells also express far higher maounts of MUC1. 
The measles virus is also a potent anti-cancer agent. After media reports elaborated on cases of people suffering cancer treated with measles virus, the UK cancer research institute, tried to downplay these findings, by pointing out that researchers used a genetically modified virus.
However, the fact that the virus was genetically modified is not relevant for its actually effect. The virus was modified to cause cells to take up iodine, which would make it easier for scientists to study the cells using radioactive iodine. The ability to cure cancer is in fact inherent to the measles virus.
In another article, cancer researcher Chris Richardson explains his discovery that many types of cancer cells are in fact covered with measles receptors. Measles receptors are a thousand times more plentiful on many types of cancer cells than they are on normal cells. According to Chris, the measles virus actually kills the cells after infecting them, while leaving healthy cells unharmed. In addition, the virus can make these cells visible to the immune system.
A number of studies confirms the reduced risk of cancer after natural measles infection. In 1970, an infant with advanced Hodgkin’s disease underwent spontaneous regression after natural infection with the measles virus.
A 2012 study found a 15% reduction in risk of non-Hodgkin lymphoma in those who reported a natural infection with measles or whooping cough. Montella found in 2006 that all childhood diseases are negatively associated with Hodkin lymphoma. The effect appears to be cumulative, as for Hodgkin lymphoma, three or more childhood diseases was associated with an eighty percent reduced risk.
Albonico found that measles infection is associated with 55% reduced odds of non-breast cancers, while chickenpox is associated with 62% reduced odds and rubella with 38% reduced odds. Alexander et al found that a history of natural measles infection is associated with a 47% reduction of hodgkin’s disease.
In conclusion, the evidence demonstrates that the long-term benefits of natural childhood infections exceed the dangers for our population as a whole. In addition, the precautionary principle should be applied in our treatment of viruses as well. For us to decide based on our limited knowledge to eradicate viruses that have infected the human population for hundreds of years is an irresponsible decision, that may come to severely effect the health of future generations.
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