Varicella and Zoster, 2016
During 2016, 336 varicella cases (6.0 per 100,000 population) were reported. One hundred seventy-four (52%) were from the metropolitan area. Cases ranged from 5 weeks to 69 years of age. Thirty-two cases (10%) were <1 year, 154 (46%) were 1-6 years, 74 (22%) were 7-12 years, 21 (6%) were 13-17 years, and 55 (16%) were ≥18 years of age. Five cases were hospitalized; one was 3 years, and 4 were >12 years of age. Three had severe disease and/ or complications including bacterial superinfection, Guillain-Barré syndrome, and prolonged rash. Three were immunocompromised and 1 had a co-morbidity. Four had never received varicella-containing vaccine; 2 had medical contraindications, 1 had a history of childhood disease, and 1 was unvaccinated for unknown reason(s). One case with a predisposing condition had been vaccinated with 1 dose of varicella vaccine. There were no varicella-related deaths.
Varicella is sometimes identified by parents/guardians reporting to schools and child care facilities, rather than diagnosed by a clinician. Of the 335 cases for which information regarding diagnosis was available, 249 (74%) had visited a health care provider, 25 (8%) had consulted a provider or clinic by telephone, 11 (3%) had been identified by school health personnel, and 50 (15%) had not consulted a clinician. Of the 320 cases for which information regarding laboratory testing was available, 97 (30%) had testing performed.
A varicella outbreak is defined as ≥5 cases in the same setting. Outbreaks in Minnesota K-12 schools have been declining markedly in number and size since vaccination requirements were phased in beginning in 2004. In 2016, no schools reported outbreaks. One child care center reported an outbreak with 9 cases. Six cases had received 1 dose of varicella vaccine as recommended for their age group, and all had a mild rash (<50 lesions). Three cases were unvaccinated; 1 was underage for vaccination, and 2 were unvaccinated due to parental refusal. Two unvaccinated cases had more than 50 lesions and 1 had over 250 lesions. Only the case with the most severe rash had fever, and no complications or hospitalizations were reported.
Zoster cases in children <18 years of age are reportable; 85 cases were reported. Cases may be reported by school health personnel, child care staff, or healthcare providers. Ages ranged from 7 months to 17 years (median 10 years). Varicella vaccine became a requirement for entry into kindergarten and 7th grade in 2004, and the incidence of zoster in children has declined from 15.7 per 100,000 population in 2006 to 6.6 per 100,000 population in 2016. Zoster with dissemination or complications (other than post-herpetic neuralgia) in persons of any age is also reportable; 64 such cases were reported, and 56 were hospitalized. Thirty-one (48%) cases were >60 years, 21 (33%) were 30 to 59 years, and 12 (19%) were <30 years of age. Thirty-seven (58%) had co-morbidities or were being treated with immunosuppressive drugs. Nineteen cases had disseminated rash or disease, 16 had meningitis, 11 had cellulitis or other bacterial superinfection, 9 had encephalitis or meningoencephalitis, 7 had Ramsay-Hunt Syndrome, and 2 had Bell-like palsy. Immunocompromising conditions and immunosuppressive drug treatment were more common among cases with disseminated rash or disease (68%) than among those with meningitis without dissemination (6%). Two deaths occurred, 1 in a case with encephalitis and 1 with disseminated disease.
- For up to date information see>> Varicella (Chickenpox)
- Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2016