Tag Archives: immune system

The Slow Journey from HPV Infection to Cervical Cancer

Healthy cervical cells as seen under a microscope. Image: National Cancer Institute

Healthy cervical cells as seen under a microscope. Image: National Cancer Institute

January is Cervical Health Awareness Month. The biggest threat to cervical health is human papillomavirus, or HPV, a virus that is transmitted through a wide variety of sexual activities. If you haven’t yet been sexually active, the best thing you can do to protect cervical health (whether you have a cervix or not) is to be vaccinated against HPV. If you have been sexually active, the vaccine could still be effective, assuming you haven’t already been infected with the strains of HPV against which it protects. And, if you are, or have been, sexually active and have a cervix, it is important to be screened with regular Pap tests (also called Pap smears). When caught in its precancerous stages, cervical cancer can be avoided.


The human papillomavirus may be tiny, but it packs a punch.


There are more than 100 strains of HPV, approximately 40 of which can be sexually transmitted; of these, 18 strains are thought to cause cancer. Chronic infections by cancer-causing HPV strains, such as HPV-16 and HPV-18 (which together are responsible for 70 percent of cervical cancers), can lead to the development of abnormal cells, which might eventually become cancerous.

In the United States, HPV is the most widespread sexually transmitted infection – 6 million Americans are infected with HPV annually, although most are asymptomatic and unaware they were infected. For most people, the infection clears up within 8 to 13 months, while for others, the infection can lurk undetected. If you are unlucky enough to develop a chronic HPV infection, then you are at increased risk for certain cancers — depending on the site of the infection, HPV can cause cancers of the cervix, anus, and other genitals, as well as the throat. Continue reading

STI Awareness: Intestinal Parasites

This is a colorized scanning electron micrograph of Giardia lamblia, which is in the process of reproducing via binary fission. Image by Dr. Stan Erlandsen, provided by the CDC's Public Health Image Library.

This colorized scanning electron micrograph shows Giardia lamblia reproducing asexually. Image: Stan Erlandsen, CDC’s Public Health Image Library.

Most sexually transmitted infections are caused by bacteria or viruses, but some are caused by organisms that are classified as completely different lifeforms. Trichomoniasis, for example, is caused by a protozoan organism; protozoa occupy their own kingdom, separate from plants, animals, and bacteria. Intestinal parasites are often protozoan organisms, but can also include parasitic worms (which are members of the animal kingdom). They are spread through contact with fecal matter – and as such, they can be transmitted sexually as well as nonsexually. Intestinal parasites are usually transmitted by fecal contamination of food or water, and are most common in areas with insufficient sewage treatment and untreated water in the wilderness. Some pathogens, however, have low infectious doses, making their sexual transmission more likely.


What has eight flagella and can live in your intestines?


Oral contact with the anus, also called anilingus or rimming, is the primary means of the sexual transmission of these pathogens. Putting fingers or hands in your mouth after they have had contact with the anus is also risky. Other modes of transmission include oral sex, as genitals can be contaminated with feces, as well as sharing sex toys and other equipment. For these reasons, it is very important to use dental dams or latex gloves during contact with the anus; to clean the anus before engaging in rimming; to clean or use condoms on shared sex toys; and to use condoms or dental dams during oral sex. Continue reading

STI Awareness: The Future of Treatment for HIV/AIDS

This scanning electron micrograph shows HIV particles infecting a human T cell. Most strains of HIV cannot enter T cells that don't have a CCR5 co-receptor on the surface. Photo: National Institute of Allergy and Infectious Diseases, National Institutes of Health

This scanning electron micrograph shows HIV particles (colored yellow) infecting a human T cell. Image: National Institute of Allergy and Infectious Diseases, National Institutes of Health

In 2006, an HIV-positive man was diagnosed with leukemia. First he received chemotherapy, and when the cancer returned his doctor recommended a stem-cell transplant with tissues obtained from a bone-marrow donor. After finding an unusually high number of compatible donors, his doctor, Gero Hütter, had a simple idea that would change the course of HIV research. Dr. Hütter knew of a rare genetic mutation that confers immunity to many strains of HIV, including the strain that infected his cancer patient. And new blood cells, including immune cells, are manufactured by bone marrow. What if he could find a bone-marrow donor with this mutation? What effect would it have on the HIV infection?

Five years after his cancer diagnosis, the man, known as the Berlin patient and recently identified as Timothy Ray Brown, is in remission from cancer … and the most sensitive tests have been unable to detect HIV anywhere in his body, despite the discontinuation of antiretroviral drugs. Scientists are a cautious lot, careful not to make grand statements without qualifying them with words like “seem” and “suggest.” But more and more, researchers are starting to say that Brown could be the first case in which a cure for HIV was attained.

Human immunodeficiency virus, or HIV, has been the focus of intense research since the 1980s, when it was identified as the causative agent of AIDS. Many anti-HIV drugs have been developed since then, though worldwide, less than a third of people who need the drugs have access to them. Those with access, however, have significantly improved health outcomes and longer life expectancy. Continue reading

What is HIV?

December 1st is World AIDS Day, so we’re focusing on HIV this month in our STI Awareness series.

Let’s break down the name:
H – Human: This virus only infects humans and is only passed from human to human.
I – Immunodeficiency: This virus weakens the immune system by destroying cells that fight disease and infection.
V – Virus: This is a virus. Unlike other viruses, however, this virus does not leave the body. This is the mystery that scientists and doctors are working to solve.

HIV is an immune system virus. It hides for a long time in your cells and attacks the T-cells, aka: CD4 cells. Over time HIV can destroy so many CD4 cells that your body cannot fight infection anymore. When that happens, HIV leads to AIDS. While all of this is very scary, the bright spot is that this is an easily preventable disease. Continue reading

STI Awareness: Cytomegalovirus and Molluscum Contagiosum

Most sexually transmitted infections (STIs) are caused by microorganisms – lifeforms that are too small to be seen without a microscope. Many STIs, however, are caused by viruses, which technically aren’t even alive. Rather, viruses are pieces of genetic information that are stored in protein capsules. When these capsules come into contact with a host cell, the genetic information is able to enter the cell and hijack its machinery so that the host cell manufactures copies of the virus, as well as potentially harmful viral proteins. Many well-known STIs, such as herpes and HIV/AIDS, are caused by viruses, but this month we will focus on two lesser-known viral STIs, cytomegalovirus and molluscum contagiosum. Your local Planned Parenthood health center, as well as other clinics, health departments, and private health-care providers, can help you get a diagnosis and treatment for these STIs.

Cytomegalovirus leaves granules inside its host cells called inclusion bodies, pictured here. Photograph from the CDC’s Public Health Image Library.

Cytomegalovirus leaves granules inside its host cells called inclusion bodies, pictured here. Image: Public Health Image Library, CDC

Cytomegalovirus

The bad news is that most people are infected with cytomegalovirus (CMV) at some point in their lives. About 80 percent of the U.S. population is estimated to be carriers, about 4 in 10 Americans are infected with CMV before puberty (usually through contact with saliva), and adults can be reinfected through sexual activity. The good news is that among healthy adults, a CMV infection usually does not have any symptoms, though if they do they could seem like a mild case of mono. Being reinfected with the virus later in life also carries with it only a small risk for symptoms in healthy adults.

And back to the bad news: While an infection with cytomegalovirus usually does not have symptoms, if someone is infected while pregnant it can harm the fetus. About 1 in 100 U.S. babies is infected with CMV, but usually doesn’t show symptoms. Every year in the United States, around 5,500 babies are born with symptomatic cytomegalic inclusion disease (CID). Symptoms of CID vary, but the most severe include mental retardation and hearing loss. If the mother was already infected before conception, there is a 2 percent chance the virus will be transmitted to the fetus; however, if the infection occurs during pregnancy, this risk jumps into the 40 to 50 percent range. Continue reading

STI Awareness: Trichomoniasis

Trichomonas vaginalis, the parasite responsible for trichomoniasis, is pictured in this electron micrograph adhering to vaginal epithelial cells. Normally pear-shaped, this organism flattens itself out after attaching to the cell in order to maximize surface area between parasite and host. Image courtesy of Antonio Pereira-Neves and Marlene Benchimol, Santa Ursula University, Rio de Janeiro, Brazil

Trichomonas vaginalis, normally pear-shaped, flattens itself out after attaching to vaginal epithelial cells, maximizing surface area between parasite and host. The purple rod-shaped organisms are bacteria. Image courtesy of Antonio Pereira-Neves and Marlene Benchimol, Santa Ursula University, Rio de Janeiro, Brazil

Most sexually transmitted infections are caused by viruses or bacteria. STIs caused by viruses include herpes and genital warts, and the viruses that cause them aren’t even technically living organisms – they are pieces of genetic information that are able to infect a host cell. STIs caused by bacteria include gonorrhea and syphilis; bacteria are microscopic, single-celled organisms with relatively simple cell structures.

But some STIs are caused by other types of living organisms. Protozoan organisms are microscopic and unicellular, like bacteria; unlike bacteria, their cell structures more closely resemble that of the so-called “higher” life forms such as animals and plants. While protozoa are considered to be “animal-like,” they are not animals at all – they are single-celled organisms that reproduce asexually. When certain types of protozoans get into your body, they can cause infections – such as trichomoniasis, the most common curable STI among young females (as well as more females over 40 than previously thought). It is estimated that 7.4 million new cases of trichomoniasis occur annually in the United States; worldwide, there are about 170 million cases each year.

Trichomoniasis, colloquially known as trich, is spread by vaginal or anal intercourse, direct vulva-to-vulva contact, and other activities that involve passing secretions from one partner to another (e.g., sharing sex toys or mutual masturbation). Sexually active people can reduce the risk of contracting trichomoniasis by using latex barriers, such as condoms. Continue reading

Can Cranberry Juice Cure Urinary Tract Infections?

Cranberry products have a reputation for fighting urinary tract infections. But is this reputation deserved? Image: FreeDigitalPhotos net

Cranberry products have a reputation for fighting urinary tract infections. But is this reputation deserved? Image: FreeDigitalPhotos net

An increased urge to urinate. A burning sensation when you do. These are two of the signs of a urinary tract infection (UTI), an incredibly unpleasant condition that can seem to come out of nowhere. Anyone can get a UTI, but among adults they are about 50 times more common in females than in males. Certain microorganisms cause these infections, often when bacteria from feces are introduced into the urinary tract. Although symptoms often clear up without medical intervention, it is very important to seek treatment for a persistent UTI because the infection could spread and become much more serious. (If you are or have been sexually active, it is also important to make sure you don’t actually have a sexually transmitted infection.)

Cranberry products – either as juice (sweetened, unsweetened, or blended with other fruit juices) or capsules – are considered by many to be an effective home remedy for UTIs. While cranberries are a well-known and accessible treatment, the evidence for their efficacy is not very strong. Why, then, are they such a popular treatment? It could be due simply to the placebo effect, an amazing phenomenon in which our expectations help shape our experiences. It could be that symptoms often clear up on their own, but we attribute our improvement to whatever remedies we happened to be trying at the time. It could be that drinking extra fluids (e.g., cranberry juice) helps flush the bacteria from our bodies as we urinate more. Or, it’s possible that cranberries do help clear up UTIs, but we just don’t have solid evidence yet. Continue reading

STI Awareness: Hepatitis B Virus and the HBV Vaccine

Hepatitis B virions are pictured in this transmission electron micrograph. Image taken from the National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention.

July 28 is World Hepatitis Day. This month’s installment of our STI Awareness series will shine the spotlight on the hepatitis B virus (HBV), which can be transmitted sexually as well as nonsexually.

Hepatitis viruses infect the liver. Hepatitis A, B, and C can be transmitted sexually, and hepatitis B is the most likely to be spread this way. HBV is present in vaginal fluids, semen, and blood. It is highly contagious and can be transmitted by most sexual activities, such as vaginal or anal intercourse, as well as oral sex. HBV can also be spread by exposure to infected blood, and an HBV-infected mother can pass the virus onto her infant during birth.

To protect yourself from HBV, make sure to use latex barriers, such as condoms and dental dams, if you are sexually active. Also, don’t use unsterilized needles; don’t share hygiene items that could have infected blood on them, such as razors and toothbrushes; and consider being vaccinated against hepatitis B. Continue reading

STI Awareness: Gonorrhea

Neisseria gonorrhoeae, the bacteria species that causes gonorrhea, is pictured here in a photograph taken with a scanning electron microscope. Projecting from the organism’s surface are many pili, powerful appendages that enable the bacteria to adhere to human cells. Image from the National Institute of Biomedical Imaging and Bioengineering.

April is STD Awareness Month, but this blog has sought to increase your awareness of sexually transmitted infections on a monthly basis. So far in 2011 we’ve pointed the spotlight at human papillomavirus, barrier methods, and herpes. This month’s installment will focus on gonorrhea, colloquially known as “the clap,” a common sexually transmitted infection caused by sneaky bacteria called Neisseria gonorrhoeae. It is spread by vaginal, anal, and oral sex, and can infect certain cells in the throat, mouth, rectum, urethra, or cervix. It can also be transmitted manually to infect the eye. If you are sexually active, you can reduce risk of transmission by consistently and correctly using latex barriers such as condoms and dental dams.

Four out of five females infected with gonorrhea do not experience symptoms – males, however, usually do, but they can be mild and therefore easy to overlook. Symptoms can appear within a month, and might include painful or frequent urination, vaginal or penile discharge, painful bowel movements, itching, or sore throat. Additionally, females can experience abdominal pain, fever, irregular menstruation, or bleeding between periods. In pregnant women, untreated gonorrhea infections can lead to complications such as premature labor or stillbirth. The infection can also be passed from mother to infant during delivery.  Continue reading