Written by Ben Bunting: BA(Hons), PGCert.
Mumps is a highly contagious viral infection. It is not life-threatening, it would rarely kill anyone, but it causes many complications, including infertility in men and women.
Fortunately, vaccination can prevent the majority of its cases.
One of the primary signs of the condition is parotitis or inflammation of the saliva gland. However, this inflammation is reversible and subsides within a few days.
Since it does not appear to cause severe health issues, people tend to neglect It without understanding that it can affect other mucosal tissues and cause severe and long-lasting complications.
Moreover, the virus is highly contagious. Despite the availability of vaccines, it is not possible to eradicate it, and some people continue to serve as its reservoir.
In this article, we shall cover the following areas:
- MMR vacinations
- MMR outbreaks
- Mumps and male infertility
MMR vaccine may help prevent, but not in all the cases
Fortunately, there is an effective vaccine that is relatively safe, too. Most would get this vaccine during their childhood. It is one of the antigens in the measles, mumps, and rubella (MMR) vaccine.
The first dose of this vaccine is given at 12 to 15 months and the second dose between the ages of 4 to 6 years.
Most countries started introducing this vaccine in the late 1980 or early 1990s, and it is now among the essential childhood vaccines.
MMR outbreaks occur despite the vaccination drive
There are many reasons for the mumps outbreaks in young men or even adults.
For example, an Irish study found an alarming rise in mumps and testicle problems in young men related to the outbreak in 2010 onward.
It is because many of these young boys and men were never vaccinated, as vaccination was introduced much later.
But of course, there are other reasons, too. The vaccine is not 100% effective, and the immune response also appears to decline with age.
CDC states that the effectiveness of a single vaccine dose is about 78%, and dual dose effectiveness is about 88%.
This is quite good but not perfect. Moreover, a significant number of people fail to develop adequate immunity against mumps despite vaccination.
Although the vaccination failure rate is relatively low, it is still relevant since the virus is highly contagious.
It means that during outbreaks, many may contract the infection.
There are many reasons for vaccine failure. Some just do not respond to vaccines due to genetic reasons.
In others, vaccine fails to produce enough antibodies. In some individuals, there is a rapid decline in antibodies after vaccination.
However, it is worth understanding that despite the failure of the vaccine, many of those vaccinated are much less likely to get severely ill or have complications like infertility.
Further, it is worth noticing that a new kind of challenge has emerged in recent years, called vaccine hesitancy.
Studies show a slight decline in vaccination rates in various nations. This decline is just small to date, yet it is one of the emerging areas of concern.
Many parents fail to understand that refusing the MMR vaccine may have grave and debilitating consequences for their child, and mumps is not just about inflammation of the saliva gland.
Mumps may cause severe complications
Indeed, mumps may not kill, but they can cause severe complications (such as meningitis) and disability.
For example, it causes severe orchitis or swelling of testicles in men, oophoritis or swelling of ovaries in women, encephalitis or brain swelling, meningitis, and even temporary or permanent hearing loss.
Thus, taking mumps as a serious illness is vital, as mortality rate is not the sole indicator.
Moreover, many men affected by mumps may only realize much later that they became infertile due to mumps they contracted several years back or in their teenage.
Mumps and male infertility
There is a strong association between mumps and male infertility, which is long known to science.
In fact, male infertility is among the leading complications of the condition.
Orchitis or testicular inflammation is the most common complication of mumps.
Studies show that mumps causes orchitis in as many as 20%-30% of cases, which is relatively high.
What is worrisome is that post-pubertal men are more prone to the condition.
These are the men who would like to have children, and the news of infertility may be devastating for them.
Studies show that in 10-30% of cases, orchitis is bilateral and is unilateral in the rest of the cases.
Thus, mumps is more likely to cause sub-fertility rather than absolute infertility.
It appears that the virus starts attacking testicular cells within a few days of starting of illness.
It causes severe inflammation of the testicles. Prolonged inflammation may cause testicular atrophy in some.
Fortunately, testicular inflammation is not permanent, and damage to testicles is reversible in most cases.
Nevertheless, injury to testicles is too widespread in some cases, causing sub-fertility or even infertility.
Another disturbing thing to know is that testosterone-producing Leydig cells are also affected.
This causes a prolonged decline in testosterone levels in young men. It often takes several months for testosterone levels to return to normal levels.
This reduction in testosterone is also vital to understand as young men need testosterone for their growing bodies, muscle mass, developing masculinity.
However, it means that if teenagers are affected by it, it may also slow down physical development.
Although mumps rarely causes complete infertility but is the common cause of sub-fertility.
Experts think it may cause reduced fertility in 10-15% of individuals. However, infertility may occur in 30-87% of cases of bilateral orchitis.
To conclude, mumps rarely results in fatal outcomes, but it can cause many complications, including infertility in men and women.
Fortunately, the MMR vaccine can prevent most of these infections and complications.
However, the vaccine is not 100% effective, and additionally, low vaccination rates in some parts of the world are making things worse. Thus, mumps is one of the preventable causes of infertility.