Tag Archives: immune response

STD Awareness: Trichomoniasis, the Pear-Shaped, Blood-Sucking, Silent Scourge

Posted on by

What’s shaped like a pear, hangs with a posse of bacteria, and is a silent scourge upon millions of urogenital tracts? I hope you guessed Trichomonas vaginalis, the single-celled parasite that causes trichomoniasis, or trich (pronounced “trick”). Trich is the most common curable sexually transmitted disease out there — currently afflicting around 3.7 million Americans and 156 million Earthlings.

These single-celled creatures pack a punch, but the body fights back.

When trich causes symptoms, sufferers might experience vaginal discharge (which sometimes has a bad odor), penile burning or discharge, spotting, and itching or swelling in the genital area. But around 70 percent of infections have no symptoms at all, making it a mostly “silent” disease. Based on the totality of the evidence, the Centers for Disease Control and Prevention (CDC) doesn’t currently recommend routine screening for trich in people without symptoms.

But it’s the subject of some debate. Since both symptoms and screenings are rare, and the disease isn’t reportable, some health experts worry that trich could be doing a lot of damage right under our noses. An infection during pregnancy could increase risk for preterm labor or low birth weight. It can increase risk for both acquiring and transmitting HIV from or to a partner. Women with trich are more likely to acquire an HIV infection when sexually exposed to the virus — in fact, one study estimated that 6.2 percent of all HIV infections among U.S. women could be attributed to trich. It’s also easier to catch HIV from a man with trich than from a man without trich. Continue reading →

STD Awareness: Searching for an HIV Vaccine

Posted on by

Ever since the dawn of the AIDS era, researchers have worked nonstop to develop an HIV vaccine. In 1984, Margaret Heckler of the U.S. Department of Health and Human Services famously (over)promised that a vaccine would be ready for testing in two years. But it’s taken much, much longer. This Saturday, May 18, is HIV Vaccine Awareness Day, a celebration of the patients, community members, and scientists who are hard at work bringing this vaccine into existence.

Only one vaccine — still in the experimental stage — has shown any effectiveness against HIV.

Hiding from the Immune System

Vaccines are inspired by our own bodies’ ability to fight disease. Usually, when our immune system encounters a threat, it takes note of the viral “antigens,” which are like facial features — a button nose, say, or dramatically arched eyebrows — that make it instantly recognizable. It creates “antibodies,” weapons that can target those antigens like guided missiles. Often, the immune system can remember the distinguishing facial features so it’s ready to attack if the enemy ever returns — giving us immunity, possibly for life.

Vaccines take advantage of our natural ability to create these immune memories by exposing our immune systems to antigens without actually exposing us to infectious viruses. Think of it as a “wanted” poster that helps the immune system recognize “bad guys” before it actually sees them on the street, enabling it to attack and destroy them before they cause disease. Continue reading →

STD Awareness: Is HPV Now a “Men’s Disease”?

Posted on by

Human papillomavirus, or HPV, is most notorious for causing cervical cancer — making it, in many people’s minds, a “women’s disease.” But this gender-blind sexually transmitted virus can cause cancer in any cell it infects, and is associated with cancers of the cervix, anus, vagina, vulva, penis, and mouth and throat — aka oropharyngeal cancer.

While oropharyngeal cancers used to be caused mostly by tobacco, as people quit smoking an increasing proportion is caused by HPV. In the 1980s, only 15 percent of oropharyngeal cancers were caused by HPV, but nowadays the virus is behind 70 percent of them. A 2011 study predicted that the number of HPV-positive oropharyngeal cancers will surpass cervical cancers by 2020.

HPV is rapidly gaining prominence among men.

It’s only 2017, but we’re ahead of schedule. Earlier this year, researchers reported that, in the United States, oropharyngeal cancer is more common among men than are cervical cancers among women — and oropharyngeal cancer rates are increasing in the male population, while they are relatively stagnant among women. These rates are projected to continue climbing, which will skew oropharyngeal cancer even more heavily toward the male population. But, in the public’s imagination, HPV is most well-known for its association with cervical cancer — while most people haven’t even heard of oropharyngeal cancer.

Oropharyngeal Cancer and HPV

Oropharyngeal cancer can strike the inside of your mouth and throat. Risk factors include tobacco (including cigarettes, snuff, and chewing tobacco), marijuana use, alcohol, and oral infection with HPV. HPV can be spread by most sexual activities — including vaginal, anal, and oral sex, as well as “French kissing” and rubbing genitals together. There are many strains of HPV, which come in two main categories: low-risk HPV, which can cause genital warts; and high-risk HPV, which can cause cancer. Continue reading →

Some Good News About Three Sexually Transmitted Viruses

Posted on by

Scientists are hard at work finding ways to improve your health!

With so much bad news emblazoned across headlines in every newspaper you look at, the world might seem like a gloomy place. So let’s take one depressing subject — disease — and peel away the sad outer layer to find silver linings of optimism.

When it comes to infections, a lot of us blame one thing: germs, also known as “bugs” — “pathogens” if we’re fancy. Some people might not think of infectious diseases as being that big of a deal — after a round of antibiotics, you’ll be on the mend. Unfortunately, antibiotics only work for bacteria, but a lot of diseases are caused by other types of germs — for which antibiotics are no match. One type of germ is called a virus, and they can’t be cured. Sometimes they can be prevented with vaccines or treated with drugs. For example, the major strains of human papillomavirus (HPV) can be prevented with a vaccine called Gardasil, herpes simplex virus can be suppressed with antiviral drugs, and HIV can be controlled with antiretroviral drugs — but none of these infections can be cured. HPV is usually defeated by the immune system, but herpes and HIV are with you for life.

But it’s not all bad. Around the world, individual scientists have picked their “favorite” viruses and are devoting their lives to finding better prevention strategies, better treatments, and even cures. Let’s check in with some of the latest headlines touting the successes of science.

New Hope for a Herpes Vaccine

A herpes vaccine would be a blockbuster — given how common this sexually transmitted infection is, a preventive shot could help a lot of couples discuss their herpes status without as much fear of judgment and stigma.

Herpes might cause an “outbreak” — unpleasant symptoms that include genital sores — but afterward the virus goes dormant in the nerve cells, hiding from the immune system. In some people, the virus can come out of its dormancy to cause flare-ups of symptoms, but once it’s had its fun it retreats back to the nerve cells.

Earlier this year, media reported on a promising new candidate for a herpes vaccine. Using a completely different strategy than previous, failed herpes vaccines, the researchers behind this breakthrough targeted the part of the virus that allows it to hide from our immune systems. If this vaccine works as hoped, recipients will be able to mount an immune defense when exposed to the virus, blocking it from establishing a permanent home in nerve cells. It might even suppress outbreaks in people who already have herpes. Continue reading →

STD Awareness: Is There a Vaccine for Syphilis?

Posted on by

Before antibiotics, syphilis was the most feared sexually transmitted disease (STD) out there. It was easy to get, quack cures were ineffective and often unpleasant, and it could lead to blindness, disfigurement, dementia, and even death. Syphilis rates were highest during World War II, and plummeted when penicillin became widely available later in the 1940s. By 2000, syphilis rates hit an all-time low, and many scientists thought the United States was at the dawn of the complete elimination of syphilis.

What a difference an antibiotic makes. Image: CDC

Unfortunately, it soon became apparent that syphilis wasn’t ready to go out without a fight. Since 2000, syphilis rates have nearly quadrupled, climbing from 2.1 to 7.5 per 100,000 people by 2015 — the highest they have been since 1994. If you look at the above graph, you might think syphilis rates have been pretty stable over the past 20 years — but if you zoom in, the fact that we’re in the midst of an epidemic becomes more clear.

After hitting an all-time low in 2000, syphilis rates have been increasing nearly every year since.

The epidemic is disproportionately affecting men who have sex with men (MSM), with Arizona seeing a higher-than-average syphilis rate in this group. Additionally, syphilis rates are climbing among women, who have seen a 27 percent bump between 2014 and 2015. And, since women can carry both syphilis and pregnancies, a rise in syphilis in this population also means a rise congenital syphilis (the transmission of syphilis from mother to fetus), which causes miscarriages, stillbirths, preterm births, neonatal death, and birth defects. Ocular syphilis — that is, syphilis infections that spread to the eyes and can lead to blindness — is also on the rise.

Men, women, babies — no one is immune to the grasp of syphilis. Continue reading →

Why Do Newborns Need the Hepatitis B Vaccine?

Posted on by

The first vaccine a baby receives — within hours or days of birth — protects them from hepatitis B virus (HBV). In a lot of people’s minds, HBV is associated with drug use and sexual activity — which stigmatizes people who have been infected with HBV or are carriers of the virus. Unfortunately, this stigma causes a lot of people to question why babies even need to be vaccinated against it, often pointing to “Big Pharma” conspiracy theories. A lot of other people are put off by the misconception that the HBV vaccine is made with human blood (it’s not).

May is Hepatitis Awareness Month, a time to learn about a childhood vaccine that’s saved millions of lives.

There are perfectly good reasons to vaccinate babies against HBV, mainly that HBV is the leading cause of liver cancer, itself one of the Top 10 types of cancer worldwide. Nine out of 10 infants born to a mother who is an HBV carrier will develop chronic infections and become carriers themselves — and a quarter of them will die prematurely of liver disease. Babies who develop chronic HBV infections are 63 times more likely to develop liver cancer than non-carriers, a connection that is 2 to 3 times stronger than the link between smoking and lung cancer.

When it comes to HBV, age at infection matters. Most people with chronic HBV infections are exposed at birth or in early childhood, when they are most likely to develop chronic, lifelong infections — whereas only 2 to 6 percent of infected adults will develop chronic infections, with only 15 percent of them eventually dying from liver disease. The fact that chronic infection risk is inversely correlated with age at infection means that birth is the time when a child is the most vulnerable to this virus — hence the importance of vaccinating as early as possible. Continue reading →

STD Awareness: Human Papillomavirus Grabs Headlines

Posted on by

Human papillomavirus, or HPV, is the most common STD out there — a fact made even more aggravating by the absence of a good test for it. Sure, Pap testing can detect cellular abnormalities triggered by HPV, and the HPV DNA test can find evidence of infection. But it’s not a definitive test — a negative Pap/HPV DNA co-test doesn’t rule out the possibility that you carry the virus. Ditto for the anal Pap test — which most people haven’t even heard of anyway!

There are more compelling reasons to vaccinate boys against HPV — and not-as-compelling reasons to think Gardasil could protect against skin cancer.

The lack of a good diagnostic test makes the HPV vaccine an even more valuable asset. If we can drive the virus to extinction through aggressive vaccination campaigns, our limited diagnostic abilities become a moot point. And recent headlines have given us reasons to love the HPV vaccine even more.

HPV and Men

Many people think of HPV as a women’s issue, as the virus causes cervical cancer, and for a long time, boys and men weren’t even targeted for vaccination. But HPV is everyone’s issue — genital warts don’t care what gender you are, and cancer-causing strains of HPV cause most cases of anal cancer, penile cancer, and oropharyngeal cancer. Recently, a large, first-of-its kind study published in JAMA Oncology analyzed penile swabs provided by 1,757 men to figure out how common HPV is in this population. (While there is no FDA-approved test for diagnosing male patients with HPV, scientists can still collect swabs for research purposes.)

The results: 45.2 percent of American men ages 18 to 59 carry genital HPV — for a total of nearly 35 million adult males. HPV carriers can transmit the virus to sexual partners through vaginal, anal, or oral sex — or even just rubbing genitals together, as the virus is spread by skin-to-skin contact. Furthermore, a quarter of men are infected with cancer-causing strains of HPV. And, while the female population sees a peak in HPV infections in their early 20s, men’s HPV prevalence increases with age. While 28.9 percent of men 18 to 22 years of age carried HPV, 50.8 percent of them carried it by the time they were 28 to 32 years of age, and 59.7 percent of 58- and 59-year-olds were carriers. Continue reading →