​​​​​​​​​​​​​​​​​APHL develops and promotes best practices, recommendations, guidelines and trainings related to STD testing through relationships with the public health laboratories and CDC’s Division of STD Prevention (DSTDP). With all three nationally reportable STDs (Chlamydia,  Gonorrhea and Syphilis) on the rise in the US and an estimated 2.6 million new STD infections occurring each year in this country, the ability to diagnose these infections is imperative. Public health laboratories serve an import role in performing high quality testing for STDs and associated antimicrobial resistance.

The most common STDs in the United States include: chlamydia, gonorrhea, hepatitis B virus (HBV), herpes simplex virus type 2 (HSV-2), human immunodeficiency virus​ (HIV), human papillomavirus (HPV), syphilis and trichomoniasis. Many of the diseases are diagnosed through the public health laboratory. Mycoplasma genitalium (MG or Mgen) is an emerging issue in the field. APHL recently published a short factsheet about Mycoplasma genitalium as well as a survey report that examines current laboratory testing capacities, capabilities and practices related to M. genitalium.

Chlamydia and Gonorrhea

Chlamydia trachomatis, the causative agent of chlamydia infection, and Neisseria gonorrhoeae, the causative agent of gonorrhea, cause a significant burden of disease. In 2019, the CDC reported over 1.8 million cases of chlamydia and over 616,000 cases of gonorrhea in the United States. Of particular concern, gonorrhea has progressively developed resistance to the antibiotic drugs prescribed to treat it, severely limiting the treatment options available. Additional resistance will significantly complicate the ability of providers to treat gonorrhea successfully. For this reason, it is critical to maintain the capability to monitor and detect emerging drug resistance in Neisseria gonorrhoeae. Lea​r​​n more.

Herpes Simplex Virus type 2 (HSV-2)

HSV-2 is the causative agent of genital herpes, a lifelong infection that can be treated but not cured. Estimates indicate that there are over 572,000 new cases per year and 18.6 million cases in the US. Approximately half of US public health laboratories surveyed in 2017 perform herpes testing.

Human Papillomavirus (HPV)

HPVs are a group of over 100 different related viruses that collectively are the most common sexually transmitted pathogen and therefore disease in the US with an estimated 13 million new infections per year and over 42 million infections total. Some of the HPV types are associated with cervical and oral cancers and there are now vaccines to prevent the types most commonly associated with these cancers. CDC recommendations on vaccination and laboratory testing should be reviewed as testing for HPV is performed in clinical and commercial laboratories; it is not commonly performed by PHLs.


Treponema pallidum, a spiral shaped bacteria, is the causative agent of syphilis. APHL worked with CDC to develop a set of three free interactive modules on syphilis serology that provide an overview of serologic methods used to diagnose syphilis infection. Diagnosis of syphilis relies on clinical indicators plus various combinations of serologic assays using testing algorithms that result in complicated reporting language. To streamline the reporting language and minimize confusion, APHL developed suggested reporting language for syphilis serology testing.


Trichomonas vaginalis, the most prevalent non-viral sexually transmitted infection in the US and worldwide, and the cause of the curable STD, trichomoniasis, is not currently a reportable or nationally notifiable disease. Laboratory diagnosis ranges from microscopy to molecular detection methods.