Isolation and Infection Spread Control Measures

Measles Containment Strategies

Measles is one of the most contagious diseases known to man; isolation (defined in Table 3-1) of cases is therefore of paramount importance. Since MeV is so efficiently spread by respiratory droplets, disinfection of fomites is not a significant part of a control strategy. Because transmission often occurs during the prodromal stage (i.e., before measles is typically diagnosed), quarantine (defined in Table 3-1) is generally ineffective as well, but should be attempted regardless, with immunization of susceptible contacts. Patients with measles should be isolated from others during the infectious period, i.e., for 4 days after the onset of rash. As shown in Figure 2-2 (Presentation and Diagnosis), the infectious period starts 4 days before the onset of rash; if a case is suspected or confirmed before rash onset (e.g., due to Koplik spots or laboratory testing in the context of an outbreak), isolation is warranted immediately and until 4 days after the rash appears. When confronted with a suspected case of measles in the office, clinicians should take immediate action to institute standard airborne precautions. These include isolating the patient from other individuals by placing them, at a minimum, in a private examination room and closing the door to the room; where available (e.g., in hospital settings), this should be a single-patient infection isolation room with negative pressure ventilation. Rooms in which suspected cases of measles were isolated should remain vacant for at least two hours after the patient leaves. Individuals with suspected measles should also be masked to further reduce the probability of transmission. All healthcare personnel in contact with suspected cases should immediately don personal protective equipment. This most prominently includes N95 respirator masks, which can prevent up to 100% healthcare-related measles cases, but it also includes eye protection, gowns and gloves. In immunocompetent patients, airborne precautions must be maintained during the entire duration of the disease instead of the usual 4 days after rash onset, because prolonged shedding of MeV occurs in these patients. Airborne precautions also apply to exposed susceptible individuals (e.g., medical personnel) from day 5 after the initial expose to day 21 after the last exposure. The Centers for Disease Control (CDC) defines exposure as either being in a shared air space (e.g., room, office, waiting room, classroom) with a person infected with measles or being in an air space vacated by an infectious person with measles within the previous 2 hours.

Once measles is confirmed, the clinician must decide whether hospitalization is indicated or whether isolation at home is sufficient. Approximately 1 in 4 patients with measles will require hospitalization for the management of measles-related complications, but hospitalization may also be indicated in cases where isolation at home is deemed impractical, and thus hospitalization rates may be higher; of the 167 measles cases registered in the first half of 2024, 88 patients (53%) were hospitalized for isolation and/or complication management. Hospitalization is generally indicated in the following cases:

• Immunocompromised patients (whether due to underlying disease or immunosuppressive therapy)
• Patients with significant physiologic instability (e.g., a Pediatric Risk of Mortality [PRISM] Score of ≥1)
• Patients with objective evidence of dehydration
• Patients with severe complications, including: croup, tracheitis, pneumomediastinum, pneumothorax, myocarditis, pericarditis, or any neurologic abnormality
• Patients requiring treatment with oxygen.

For the protection of public health and outbreak control, the local health department (HD) should be immediately informed of each suspected case of measles, and suspected cases should be confirmed as soon as possible by laboratory testing (see Presentation and Diagnosis and Prevention and Control). The local HD will then proceed to rapidly immunize susceptible individuals in the community, and, in cases where individuals cannot be immunized for any reason, exclude them from childcare, educational and healthcare settings until 21 days after the onset of rash in the last case of measles in the community. Immune and recently immunized individuals need not be excluded. Non-immune healthcare personnel and those who received PEP should be excluded from patient contact from day 5 until day 21 after exposure. Healthcare personnel who develop measles should not be in patient contact until 4 days after the onset of rash. See Prevention and Control for recommendations on outbreak control in educational and healthcare settings.

The 2018 World Health Organization (WHO) guidelines on measles surveillance recognize that, in elimination settings (such as the United States), surveillance must be case-based. If feasible, community-based surveillance (e.g., notification by community health or educational institution personnel) should also be implemented.

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