Group A Streptococcal(GAS) Invasive Disease

Reportable by Laboratories and Providers

About this Reportable Disease

Infectious agent:  Streptococcus pyogenes

Description of illness: Invasive GAS disease is a severe and sometimes life-threatening infection in which the bacteria have invaded parts of the body, such as the blood, deep muscle, and fat tissue, or the lungs. Examples of GAS invasive disease include streptococcal toxic shock syndrome (STSS), necrotizing fasciitis, pneumonia, and bacteremia. Early signs and symptoms of necrotizing fasciitis include fever, severe pain and swelling, and redness at the wound site. Early signs and symptoms of STSS may include fever, dizziness, confusion, low blood pressure, rash, and abdominal pain. Approximately 20% of patients with necrotizing fasciitis and more than half with STSS die; about 10-15% of patients with other forms of invasive group A streptococcal disease die.

Interactive Disease Data


Laboratory Reporting for this Disease

Reporting requirements apply to all laboratories located within Tennessee, as well as laboratories outside of Tennessee that test residents of Tennessee, including laboratories located within healthcare facilities. Healthcare providers and laboratories in the same healthcare facility both have a duty to report. The type of organisms and analytes laboratories must report to TDH for 2026 are indicated, and there are several ways laboratories can report results to TDH.

 

Information about this Reportable Disease for Healthcare Providers

Clinical Summary

  • Invasive group A streptococcal (iGAS) disease is a severe, sometimes life-threatening infection caused by Streptococcus pyogenes (group A strep) when bacteria invade normally sterile sites (e.g., blood) or deep tissues. Examples include bacteremia, pneumonia, necrotizing fasciitis, and streptococcal toxic shock syndrome (STSS).
  • Clinical presentation can range from severe skin/soft tissue infection to rapidly progressive systemic illness. CDC highlights that STSS can involve shock and multi-organ failure and often requires prompt antibiotics plus source control (frequently surgery); necrotizing fasciitis is a surgical emergency.
  • Diagnosis is based on compatible illness plus microbiologic confirmation (e.g., culture from a normally sterile site such as blood, CSF, pleural fluid, or deep tissue). Early recognition and immediate treatment are critical because iGAS can deteriorate quickly.
  • In Tennessee, Group A Streptococcal (GAS) Invasive Disease is reportable to TDH, supporting rapid public health response (including investigation and prevention steps for close contacts/facility exposures when indicated).

Healthcare Provider Reporting

Healthcare reporting requirements apply to all providers located within Tennessee, as well as providers whose patients reside in Tennessee.

Providers must report cases of all diseases and conditions listed through one of these methods:

• Mail or fax a completed PH-1600 form to your local health department or fax to the state health office at (615) 741-3857

• Send automatically via electronic case reporting (eCR). See this TDH webpage for more information on eCR, register at the Trader Partner Registration website, or contact MU.Health@tn.gov for assistance.

• Submit online via NBS. NBS is TDH's reportable disease system. To request an NBS account for reporting Complete this user survey to request an NBS account for reporting. 

• Blood lead levels can be sent via fax ( (615) 741-3857), entered online, or reported using the instructions at this link. 

Information about this Reportable Disease for the Public

What It Is

Invasive group A strep (invasive GAS) is a serious infection caused by Streptococcus pyogenes (group A strep) when the bacteria get into parts of the body that are normally sterile (like the bloodstream) or into deep tissues. Invasive GAS can cause severe illnesses such as bloodstream infection, pneumonia, necrotizing fasciitis (flesh-eating disease), and streptococcal toxic shock syndrome (STSS). Learn more from CDC’s overview of Group A strep and CDC information on invasive infections.

Signs and Symptoms

Symptoms depend on where the infection is, but invasive GAS often starts suddenly and can worsen quickly. Warning signs may include high fever, severe pain (especially out of proportion to what you see on the skin), dizziness, confusion, or rapidly spreading redness/swelling. STSS is a particularly dangerous form that can lead to shock and organ failure—see CDC information on streptococcal toxic shock syndrome (STSS). For a public-facing overview, this Group A strep fact sheet is also a helpful reference.

How It Spreads

Group A strep bacteria spread through close contact with an infected person’s respiratory droplets (for example, from coughing or sneezing) or through contact with infected skin sores/wounds. While many people get mild infections, invasive disease is less common but more severe. CDC provides more information about Group A strep, which includes practical prevention tips for the public.

Diagnosis and Treatment

Invasive GAS is diagnosed by healthcare providers using lab testing (often culture of blood or another normally sterile site) along with symptoms and exam findings. Treatment requires prompt antibiotics, and some severe forms (such as necrotizing fasciitis) often require urgent surgery and hospital-level care. CDC clinical guidance is available on the Group A strep clinical guidance pages, including STSS guidance.

Prevention and When to Seek Care

Good hand hygiene, covering coughs/sneezes, and keeping wounds clean and covered can reduce spread. CDC prevention steps include actions to help prevent group A strep infections in everyday settings and guidance on reducing spread in close-contact situations; see Group A strep prevention. Seek urgent medical care if someone has rapidly worsening symptoms—especially high fever with severe pain, a spreading skin infection, confusion, or signs of shock.

This Page Last Updated: March 25, 2026 at 8:53 PM