They are also known as sexually transmitted infections (STIs) or venereal diseases (VD).
Some STDs can spread through the use of unsterilized drug needles, from mother to infant during childbirth or breast-feeding, and blood transfusions.
The genital areas are generally moist and warm environments, ideal for the growth of yeasts, viruses, and bacteria.
People can transmit microorganisms that inhabit the skin or mucous membranes of the genitals. Infectious organisms can also move between people in semen, vaginal secretions, or blood during sexual intercourse.
Individuals pass on STDs more easily when they are not using contraceptive devices, such as condoms, dams, and sanitizing sex toys.
Some infections can transmit through sexual contact but are not classed as STDs. For example, meningitis can be passed on during sexual contact, but people can acquire a meningitis infection for other reasons. It is therefore not classed as an STD.
The World Health Organization (WHO) estimates that there are more than 1 million new STDs acquired each day globally.
The following sections explain the most common STD’s.
People spread STDs through sexual contact.
Chlamydia is an STD caused by Chlamydia trachomatis (C. trachomatis). This bacterium only infects humans. Chlamydia is the most common infectious cause of genital and eye diseases globally. It is also the most common bacterial STD.
According to the Centers for Disease Control and Prevention (CDC), in 2015, nearly 3 percent of girls aged 15 to 19 years had chlamydia.
Women with chlamydia do not usually show symptoms. Any symptoms are usually non-specific and may include:
- bladder infection
- a change in vaginal discharge
- mild lower abdominal pain
If a person does not receive treatment for chlamydia, it may lead to the following symptoms:
- pelvic pain
- painful sexual intercourse, either intermittently or every time
- bleeding between periods
Chancroid is also known as soft chancre and ulcus molle. It is a bacterial infection caused by called streptobacillus Haemophilus ducreyi. The infection causes painful sores on the genitals and is only spread through sexual contact.
This infection is more common in developing nations, especially among commercial sex workers and some lower socioeconomic groups. This is due to the lack of access to healthcare services, the stigma attached to seeking help, a lack of sufficient sexual health education, and other factors.
Within 1 day to 2 weeks of acquiring the infection, the patient develops a bump that turns into an ulcer within a day. The ulcer can be from 1/8 of an inch to 2 inches across. It will be very painful and may have well-defined, undermined borders and a yellowish-gray material at its base.
If the base of the ulcer is grazed, it will typically bleed. In some cases, the lymph nodes swell and become painful.
Women often have at least four ulcers, while men usually have just one. Males tend to have fewer and less severe symptoms. The ulcers typically appear at the groove at the back of the glans penis in uncircumcised males, or, in females, on the labia minora or fourchette.
Chancroid is treated with a 7-day course of erythromycin, a single oral dose of azithromycin, or a single dose of ceftriaxone.
Crabs, or pubic lice
Pubic lice manifestations are primarily spread through sexual contact. Pets do not play any part in the transmission of human lice.
The lice attach to the pubic hair, and may also be sometimes found in the armpits, mustache, beard, eyelashes, and eyebrows. They feed on human blood.
The common term “crabs” comes from the crab-like appearance of the lice.
This STD is caused by the herpes simplex virus (HSV). The virus affects the skin, cervix, genitals, and some other parts of the body. There are two types:
- HSV-1, also known as herpes type 1
- HSV-2, also known as herpes type 2
Herpes is a chronic condition. A significant number of individuals with herpes never show symptoms and do not know about their herpes status.
HSV is easily transmissible from human to human through direct contact. Most commonly, transmission of type 2 HSV occurs through vaginal, oral, or anal sex. Type 1 is more commonly transmitted from shared straws, utensils, and surfaces.
In most cases, the virus remains dormant after entering the human body and shows no symptoms.
The symptoms associated with genital herpes, if they do occur, may include:
blisters and ulceration on the cervix
- vaginal discharge
- pain on urinating
- generally feeling unwell
- cold sores around the mouth in type 1 HSV
Also, red blisters may occur on the external genital area, rectum, thighs, and buttocks. These can be painful, especially if they burst and leave ulcers.
Hepatitis B can permanently damage the liver.
The hepatitis B virus (HBV) causes this STD.
It is transmitted through contact with infected semen, blood, and other bodily fluids. HBV is passed on in the following ways:
- unprotected sex
- using an unsterilized syringe
- being accidentally pricked by a sharp object
- drinking infected breast milk
- being bitten by a person with hepatitis B
The liver swells, and an individual can experience serious liver damage as a result of HBV. This can eventually lead to cancer, and the disease can sometimes become chronic. Blood donation centers always check to make sure that any donors do not have hepatitis B.
Trichomoniasis is a common STD that can affect both sexes. However, women are more likely to experience symptoms. The infection is caused by a single-celled protozoan parasite, Trichomonas vaginalis.
For women, the vagina is the most common site of infection, while for men it is the urethra. Transmission may occur either by sexual intercourse or vulva-to-vulva contact.
While women may acquire the infection from either male or female sexual partners, men nearly always become infected from having sex with women.
Symptoms of trichomoniasis include:
- vaginal odor
- vaginal discharge
- pain or discomfort during sexual intercourse
- pain when urinating
A woman with trichomoniasis is more likely to acquire HIV once exposed to the virus. A woman with trichomoniasis and HIV is also more likely to transmit HIV virus onto other sexual partners.
HIV and AIDS
A person cannot transmit HIV if a viral load cannot be detected in the blood.
Human immunodeficiency virus (HIV) attacks the immune system, leaving its host much more vulnerable to infections and diseases. If the virus is left untreated, the susceptibility to infection worsens.
HIV can be found in semen, blood, breast milk, and vaginal and rectal fluids. HIV can be transmitted through blood-to-blood contact, sexual contact, breast-feeding, childbirth, the sharing of equipment to inject drugs, such as needles and syringes, and, in rare instances, blood transfusions.
With treatment, the amount of the virus present within the body can be reduced to an undetectable level. This means the amount of HIV virus within the blood is at such low levels that it cannot be detected in blood tests. It also means that HIV cannot be transmitted to other people. A person with undetectable HIV must continue to take their treatment as normal, as the virus is being managed, not cured.
If HIV progresses without treatment and reaches stage 3, known as AIDS, it can be fatal. However, modern medicine means that HIV need not reduce life expectancy.
Human papillomavirus (HPV)
Human papillomavirus is a name for a group of viruses that affect the skin and mucous membranes, such as the throat, cervix, anus, and mouth.
There are over 100 types of HPV, of which, about 40 can affect the genital areas. These types may also transmit to the mouth and throat.
HPV infection can lead to:
- abnormal cell growth and alteration within the cervix, significantly increasing the risk of cervical cancer
- genital warts
The majority of individuals with HPV have no symptoms and are unaware. HPV is so common in the U.S. that almost every sexually active man and woman will transmit the virus during their lifetime.
HPV is most commonly transmitted through vaginal or anal sex, oral sex, and genital-to-genital contact. People with an HPV virus but no signs and symptoms can still infect others.
A woman who is pregnant and has HPV might transmit the virus to her baby during childbirth, although this is very rare.
Vaccination is the best way to prevent HPV.
Molluscum contagiosum is a contagious, viral skin infection.
There are four types:
- MCV-1, the most common type
- MCV-2, the most commonly sexually transmitted type
When the virus infects young children, it is not considered an STD.
Symptoms include small, round bumps and indents on the skin. If left untreated, the bumps usually go away, but this can take up to 2 years. A doctor can remove the bumps with chemicals, an electrical current, or by freezing them. There are some prescription medicines that will eventually get rid of the growths.
Scabies is a contagious skin condition caused by Sarcoptes scabiei, a tiny mite. They burrow into the skin and lay their eggs.
A person with scabies develops a skin rash and experiences intense itchiness. People with scabies are often unaware of their condition for several weeks after initial infection, which means scabies infestations spread rapidly.
The cause of scabies is unknown, although some believe poor living conditions and a lack of personal hygiene are linked to the condition. However, there is no scientific proof of this.
Scabies is most commonly transmitted through close body contact, such as holding hands for a long time or sexual intercourse. Hugging or simply shaking hands with a person who has scabies is unlikely to lead to transmission.
The scabies mite cannot jump or fly. However, it can survive for 1 to 2 days after leaving the human body. This means that sharing clothes or bedding with a person who has scabies increases the risk of infection.
However, prolonged physical contact, as is likely to occur during sexual intercourse, is the most common route of transmission.
Symptoms of scabies may not occur for several weeks after initial transmission and may include:
- A skin rash: The scabies mite leaves small red spots, known as burrow marks. They look like tiny insect bites, and some people may think it iseczema. Burrow marks typically appear as a small line of at least four tiny spots and appear around the area of the elbows, wrists, and in between the toes and fingers. Women experience this rash around the nipples and men near the genitals.
- Intense itching: This gets worse at night or after taking a hot shower.
- Sores: After scratching the rash, the area can become inflamed, and crusty sores may develop.
Less commonly, the rash may appear on the buttocks, ankles, armpits, genitalia, groin, scalp, neck, face, head, shoulders, waist, soles of the feet, lower leg, and knees.
Syphilis is the result of Treponema pallidum, a bacterium. It is transmitted by sexual contact, and the person passing on the infection will have a syphilitic lesion. A woman who is pregnant and also has syphilis can pass on this STD to her baby, which can result in stillbirth or serious congenital deformities.
There is an incubation period of between 9 and 90 days after initial infection before the symptoms of the disease occur, with an average incubation period of 21 days. Each stage of syphilis has characteristic signs and symptoms. Some people with syphilis show no symptoms, while others may experience more mild presentations.
For some people with the condition, even if symptoms resolve, the bacterium is still in the body and can cause serious health problems later on.
This sexually transmitted bacterial infection usually attacks the mucous membranes. It is also known as the clap or the drip.
The bacterium, which is highly contagious, stays in the warmer and moister cavities of the body.
The majority of women with gonorrhea show no signs or symptoms. If left untreated, females may develop pelvic inflammatory disease (PID). Males may develop inflammation of the prostate gland, urethra, or epididymis.
The disease is caused by Neisseria gonorrhoeae. The bacteria can survive in the vagina, penis, mouth, rectum, or eye. They can be transmitted during sexual contact.
As soon as a person contracts gonorrhea, they risk spreading the bacteria to other parts of the body. An individual may accidentally rub their eye and spread the infection. This prolongs the treatment period. A woman who is pregnant can pass the infection on to the infant during childbirth.
Symptoms of gonorrhea may occur between 2 to 10 days after initial infection, in some cases, it may take 30 days. Some people experience very mild symptoms that lead to mistaking gonorrhea for a different condition, such as a yeast infection.
Males may experience the following symptoms:
- burning during urination
- testicular pain or swelling
- a green, white, or yellow discharge from the penis
Females are less likely to show symptoms, but if they do, these may include:
- spotting after sexual intercourse
- swelling of the vulva, or vulvitis
- irregular bleeding between periods
- pink eye, or conjunctivitis
- pain in the pelvic area
- burning or pain during urination
If the rectum becomes infected, a person with gonorrhea may experienceanal itching, painful bowel movements, and sometimes discharge. When transmission occurs as a result of oral sex, there may be a burning sensation in the throat and swollen glands.
Condoms can help prevent the spread of STDs.
Sex using a condom is the safest way to prevent the spread of STDs. Condoms are known as barrier contraceptives, due to their presentation of a physical barrier to microbes.
For each oral, vaginal, or anal sex act, use a new latex condom. Condoms are available to purchase online.
Avoid using an oil-based lubricant, such as petroleum jelly, when using a latex condom. Non-barrier forms ofcontraception, such as oral contraceptives or intrauterine devices, do nothing to protect people from sexually transmitted infections.
Here are other steps you can take to reduce the risk of an STD:
- Abstinence: Abstaining from any sexual act is the most effective way to avoid an STD.
- Monogamy to one uninfected partner: A long-term, monogamous relationship with one person who is not infected can reduce the risk of contracting an STD.
- Vaccinations: There are vaccinations that can protect an individual from eventually developing some types of cancer that are caused by HPV and hepatitis B.
- Check for infections: Before sexual intercourse with a new partner, check that the partner and yourself have no STDs.
- Drink alcohol in moderation: People who have consumed too much alcohol are more likely to engage in risky behavior. Avoid using recreational drugs, which may also affect judgment.
- Explain you want safe sex: Before engaging in any sexual act with a new partner, communicate that you would only consider safe sex.
- Education: Parents, schools, and society need to teach children about the importance of safe sex, and explain how to prevent becoming infected with an STD, including information relevant to the LGBTQ community.
Take a responsible approach to getting intimate with another person, and it could protect you from a range of health problems further down the line.