Updated: Nov 18, 2020

Written by: Kiran Iqbal, M.D.

Even though they are often used interchangeably, the acronyms STIs (Sexually Transmitted Infections) and STDs (Sexually Transmitted Diseases) refer to different entities.

While the term STD was more frequently used in the past, STI is more common now, leaving most of us confused about the distinction between the two.

In this article, we will address the difference as well as some of the commonly asked questions.

According to the World Health Organization (WHO), more than 1 million sexually transmitted infections (STIs) are acquired every day worldwide. In some cases, STIs can have serious reproductive health consequences beyond the immediate impact of the infection itself (e.g., infertility or mother-to-child transmission).

These facts highlight why it is important to keep ourselves educated and informed on the subject.

The Difference:

The distinction between the two is the basic difference between an infection and a disease. While an infection refers to the invasion of the body by a pathogen, the disease is the clinical manifestations caused by a medical problem associated with clear signs and symptoms.

Now the nature and severity of the disease depend upon the pathogen and its virulence and the host immunity. Sometimes the disruption in normal bodily function is substantial, leading to severe symptoms, while in other cases, the infection is barely symptomatic.

In short, every STD starts as an STI, but not every STI progresses to an STD.

For example, Human papillomavirus (HPV), the most common sexually transmitted infection in the U.S., according to the Centers for Disease Control and Prevention (CDC), is asymptomatic in most cases.

However, it can also cause cervical cancer in women and genital warts in both men and women. Not every woman with an HPV infection will develop cervical cancer but the ones who will have it will have developed a sexually transmitted disease. Another reason for the distinction is the stigma attached to 'STD.'

Using STI can possibly eliminate some of the shame conventionally associated with the acronym 'STD.' If a person has an STI, it means they are infected. Many times, it is possible to be infected without any discernable signs and symptoms, which leads people to think they are clean. In other cases, the signs are very mild and easily ignored. This is a dangerous situation as ignorance can lead to further transmission of the infection.

The Prevention:

Avoid having sex with anyone who has genital warts, sores, a rash, or an unpleasant discharge. In addition, you can take the following precautionary measures:

  • Abstinence: The only 100% reliable method for avoiding an STI is not having sex, whether vaginal, anal, or oral. As evident, it is not practical and sustainable for everyone.
  • Mutual monogamy: Mutual monogamy means limiting yourself to one sex partner while your partner agrees to do the same. It is one of the most reliable methods in the long run. Make you and partner get tested before getting into such a relationship.
  • Vaccination: Vaccines are an effective, safe, and reliable method for the prevention of hepatitis B and HPV infection. HPV vaccination is recommended for everyone through age 26. The first dose can be given as early as nine years of age, which will protect your child later in life. Here is the CDC schedule for HPV vaccination. Hepatitis B vaccination is recommended for anyone who was not vaccinated early in life. You can check out this CDC hepatitis B schedule for further guidance.
  • Using condoms: Male latex condoms are highly effective against STIs when used correctly and consistently. Non-latex condoms are also useful, but they have a higher breakage rate. Make sure to use a condom while having vaginal, anal, or oral sex. Natural membrane condoms are not recommended for this purpose.
  • Limiting the number of sex partners: Reducing the number of sex partners can significantly lower the risk for an STI. It is important that you and your partner get periodically tested and preferably share the results which each other.

Periodic Screening:

The distinction between the two is important to emphasize the significance of periodic screening tests. An early diagnosis can lead to more effective treatment, substantially reducing the chances of a complication. In addition, an undiagnosed infected person can pass on the infection to their sexual partners, contributing to the global burden of diseases.

According to the Centers for Disease Control (CDC), 20 million new infections are diagnosed every year in the U.S. alone. Half of the affected individuals are aged between 15 and 24 years. Considering a large proportion of those infected do not develop symptoms, it is crucial to practice safe sex and go for periodic testing.

The Causative Agents:

There are more than 30 known pathogens, including bacteria, viruses, and parasites that are transmitted via sexual contact. Eight of these pathogens are most commonly involved in several sexually transmitted diseases.

Out of the eight infections caused by these pathogens, four, syphilis, gonorrhea, chlamydia and trichomoniasis, are either bacterial or parasitic and curable. The rest are viral, namely hepatitis B, herpes simplex virus (HSV or herpes), HIV, and human papillomavirus (HPV) and are currently incurable. These, however, can be managed with treatment in order to reduce or modify the symptoms associated.

The Modes of Transmission:

STIs are predominantly transmitted by sexual contact, including vaginal, anal, and oral. They can also spread via non-sexual routes such as blood transfusion. Many STIs are transmitted from mother to child during pregnancy or childbirth, including syphilis, hepatitis B, HIV, chlamydia, gonorrhea, herpes, and HPV, causing disease in the neonate.

Despite the high prevalence of STI and STDs among young people, the stigma attached keeps them from being tested or even talking about it. It is important to realize that sexually transmitted infections are no different from any other infection and should be treated so.


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