The Delaware Division of Public Health (DPH) is issuing this Health Alert Network (HAN) advisory to inform health care professionals (HCPs) that DPH has received notification that an out-of-state individual with measles reportedly traveled through the greater Rehoboth area on September 4, 2026, visiting an unknown number of stores and restaurants. Because all locations visited cannot be fully determined, DPH is issuing a community wide notification rather than narrowing guidance to specific sites. The individual had not yet developed symptoms but was believed to have been contagious at the time of the visits. DPH received the notification after the period when post exposure treatment would have been effective. The exposure is an important reminder of the importance of vaccination for those who are eligible. Vaccination remains the best protection against measles. Two doses of the measles, mumps and rubella (MMR) vaccine are 97% effective at preventing measles.

The incubation period for measles, from exposure to fever, is usually about 10 days (range, seven to 12 days). From exposure to rash, onset is usually about 14 days (range, seven to 21 days). DPH recommends that HCPs consider the possibility of prodromal symptoms (fever, cough, runny nose and pink eye) in persons who may have been in the affected area on September 4, 2026 or travelled to areas with ongoing measles transmission, particularly among persons who have not received a measles-containing vaccine. DPH also recommends that HCPs be on alert for cases of measles that meet CDC’s case definition (https://ndc.services.cdc.gov/case-definitions/measles-2013/).

DPH recommends that appropriate signage should be considered for facility entries and waiting areas, and appropriate telephone and in-person screenings should be considered for patient triage.

If an HCP has a high suspicion of measles, this should be discussed with the patient and a strong recommendation should be provided that the patient isolate until laboratory results or other confirmatory evidence is received. DPH also recommends that HCPs should use personal protective equipment (PPE), including respiratory protection (i.e., a respirator) that is at least as protective as a fit-tested, NIOSH-certified disposable N95 filtering facepiece respirator, regardless of presumptive evidence of immunity, upon entry to the room or care area of a patient with known or suspected measles.

The DPH Measles website (https://publichealthalerts.delaware.gov/measles/) includes a variety of resources, including the following:
• Measles Screening Questionnaire for Health Care Facilities
• Resource for Administrators of Congregate Settings
• Dental Professionals and Early Diagnosis

Summary
• An out-of-state resident with measles visited Sussex County.
• Measles is very contagious and can cause serious health complications.
• The incubation period for measles, from exposure to fever, is usually about 10 days (range, seven to 12 days). From exposure to rash, onset is usually about 14 days (range, seven to 21 days).
• Common measles symptoms include high fever (may spike to more than 104° F); cough; runny nose; red, watery eyes (conjunctivitis or pink eye), and rash.
• Anyone who is not protected against measles is at risk.
• Two doses of measles, mumps, and rubella (MMR) vaccine provide the best protection against measles.
• Measles can cause serious health complications, especially in children younger than 5 years of age. Common complications are ear infections and diarrhea. Serious complications include pneumonia, encephalitis (swelling of the brain) and in some cases, death.
• Measles is reportable in Delaware. All suspected cases and positive laboratory reports should be reported immediately to DPH by emailing reportdisease@delaware.gov, by calling the Office of Infectious Disease Epidemiology at 1-888-295-5156, or by sending electronically through the Delaware EpiLab Insight (DELI) Disease Surveillance System.

Clinical Characteristics
Health care professionals (HCPs) are recommended to:
• Consider measles as a diagnosis in anyone with febrile illness and clinically compatible symptoms (e.g. rash, cough, coryza, or conjunctivitis) who has recently traveled abroad or to outbreak regions.
• Immediately notify DPH about any suspected case of measles to ensure rapid testing and investigation. Please contact the Office of Infectious Disease Epidemiology during regular business hours (302-744-4990) or the state’s 24-hour reporting line at 1-888-295-5156 outside of normal business hours.
• Recommend MMR vaccine for patients who are unvaccinated or not fully vaccinated.
• Do not allow patients with suspected measles to remain in the waiting room or other common areas of the health care facility; isolate patients with suspected measles immediately, ideally in a single-patient airborne infection isolation room (AIIR), if available. If an AIIR is not available, isolate patients in a single-patient room with a closed door.
• Follow CDC’s testing recommendations and collect either a nasopharyngeal swab or urine specimen for Reverse Transcription Polymerase Chain Reaction (RT-PCR) as well as a blood specimen for serology from all patients with clinical features compatible with measles. RT-PCR is available at many state public health laboratories and through the APHL/CDC Vaccine Preventable Disease Reference Centers.
• Ensure all patients are up to date on MMR vaccine and other recommended vaccines.
• For people traveling abroad, CDC recommends that all U.S. residents older than six months be protected from measles and receive MMR vaccine, if needed, prior to departure.

If you suspect patient exposure, either administer MMR vaccine within 72 hours of initial measles exposure or immunoglobulin (IG) within six days of exposure. The MMR vaccine and IG provide post-exposure prophylaxis (PEP) to prevent measles or modify the clinical course of disease among susceptible people. For vaccine eligible people aged ≥12 months exposed to measles, administration of MMR vaccine is preferable to using IG, if administered within 72 hours of initial exposure. The following patient groups are at risk for severe disease and complications from measles and should receive IG: infants aged <12 months, pregnant women without evidence of measles immunity, and severely immunocompromised people. IG can be administered to other people who do not have evidence of measles immunity, but priority should be given to people exposed in settings with intense, prolonged, close contact (e.g., household, daycare, and classroom). Do not administer MMR vaccine and IG simultaneously, as this practice invalidates the vaccine.

Recommendations for Prevention
The best way to protect against measles is with the measles, mumps, and rubella (MMR) vaccine. MMR is safe and effective – serious reactions are extremely rare. Two doses of MMR vaccine are about 97% effective at preventing measles; one dose is about 93% effective. Talk to your patients about the MMR vaccine, especially if they are planning to travel.

Laboratory Testing
Real-time RT-PCR (rRT-PCR): Nasopharyngeal swabs for PCR testing are preferred over urine specimens. PCR specimens can be requested to be tested at the Delaware Public Health Laboratory (DPHL). Please contact the Office of Infectious Disease Epidemiology during regular business hours (302-744-4990) or the state’s 24-hour reporting line at 1-888-295-5156 outside of normal business hours to request approval for testing at the DPHL.

For serology, collect the first (acute phase) serum specimen (IgM and IgG) as soon as possible upon suspicion of measles disease. If the acute-phase serum specimen collected ≤3 days after rash onset is negative and the case has a negative result for real-time RT-PCR (rRT-PCR), or one was not done, a second serum specimen collected three to 10 days after symptom onset is recommended because the IgM response may not be detectable until 3 days after symptom onset. As of July 2026, serology testing is not currently available at DPHL, but DPHL may be able to facilitate testing through a partner, if needed.

HCPs should use personal protective equipment (PPE), including respiratory protection (i.e., a respirator) that is at least as protective as a fit-tested, NIOSH-certified disposable N95 filtering facepiece respirator, regardless of presumptive evidence of immunity, upon entry to the room or care area of a patient with known or suspected measles.

The Delaware Public Health (DPH) Laboratory offers nasopharyngeal PCR test for measles. Non-PCR testing is not available at the DPH Laboratory. Serology must be sent to a commercial laboratory. To order a nasopharyngeal PCR test for measles through the DPH Laboratory, an ordering Provider or Infection Preventionist must first contact the DPH Office of Infectious Disease Epidemiology for testing approval at 302-744-4990. Please also fill out the test requisition. Specimens not labeled on the tube, or without two unique identifiers (Name, date-of-birth) will be rejected. After the DPH Office of Infectious Disease Epidemiology approves, testing sample pickup is coordinated between the DPH Laboratory and DPH Office of Infectious Disease Epidemiology. Once sample reaches the laboratory, testing takes four to eight working hours. Processing time may change if the volume of tests continues to increase.

Reporting
Delaware physicians, laboratories, and other health care providers are required by regulations to report patients with measles to the Office of Infectious Disease Epidemiology (OIDE) immediately upon identification. Please do not wait for test results to be available to contact OIDE. Early reporting enables appropriate public health follow-up for your patients, helps identify outbreaks, and provides a better understanding of disease trends in Delaware. Cases can be reported to the DPH Office of Infectious Disease Epidemiology (OIDE) by calling 302-744-4990 (normal business hours) or 1-888-295-5156 (outside of normal business hours). Urgent notification by phone is preferred. You may also complete a Notifiable Disease Report PDF Form and fax the form to DPH at 302-622-4149 or email to: reportdisease@delaware.gov. The form can be found online at: Reportable Diseases in Delaware – Delaware Health and Social Services – State of Delaware – Division of Public Health

For more information:

The DPH Measles website (https://publichealthalerts.delaware.gov/measles/) includes a variety of resources, including the following: Measles Screening Questionnaire for Health Care Facilities, Resource for Administrators of Congregate Settings, Dental Professionals and Early Diagnosis

Clinical Overview of Measles
Interim Infection Prevention and Control Recommendations for Measles in Healthcare Settings
Plan for Travel – Measles
Laboratory Testing for Measles
Measles Serology Testing