Vaccine-Derived Poliovirus Outbreak Minnesota, 2005 Kristen Ehresmann, R.N., M.P.H. Minnesota Department of Health

Acknowledgements Gary Wax Lynn Bahta Claudia Miller Harry Hull Ruth Lynfield Kathy Harriman Jean Rainbow Elizabeth Cebelinski Joanne Bartkus Susan Fuller Todd County Public Health And CDC!

Adverse Events Related to OPV Vaccination Vaccine-associated paralytic poliomyelitis (VAPP) Long term excretion of vaccine-derived polioviruses (VDPV) Polio outbreaks associated with circulating VDPVs in areas with low rates

What is a VDPV? Vaccine-derived polio viruses (VDPVs) are poliovirus strains derived from one of the three Sabin poliovirus strains in the oral polio vaccine (OPV) that have > 1% difference in nucleotide sequence from the prototype vaccine virus.

Types of VDPVs iVDPV Vaccine-derived polio virus in an immunocompromised individual cVDPV Vaccine-derived polio virus with sustained person-to-person transmission (community circulation)

Background On September 29, 2006 the Minnesota Department of Health (MDH) identified poliovirus type 1 in an unvaccinated, immunocompromised infant girl aged 7 months in an Amish community whose members predominantly were unvaccinated for polio.

Index Patient Unvaccinated, 7 month old Amish girl Born at home; 3 unvaccinated siblings Poliovirus type 1 identified in stool sample No paralysis Hospitalized for pneumonia at a community hospital in July 2005 Continuously hospitalized since August 22, 2005 Failure to thrive, diarrhea, recurrent infections

Index Patient (cont.) Diagnosis of severe combined immunodeficiency (SCID) made September 15, 2005 Treated with high PV1 titre IVIG with assistance from FDA Still shedding virus after failed Bone Marrow Transplant (BMT) Second BMT successful engraftment, no longer shedding virus

Community Investigation Newly formed Amish community in Central MN made up of 24 families Parents and some elders vaccinated 1979 Visitors from Amish Communities in MN, WI, MI, Ontario including large weddings No community members with travel outside North America

Community Investigation Simple lifestyle, including use of outhouses Door-to-door interviews conducted by MDH and local PH staff re: polio vaccination status, immune status, and recent illnesses Stool samples collected 32 persons/5 households Serum specimens collected on 7 persons/2 households

Hospital Investigation All 4 hospitals evaluated for nosocomial transmission At Hospitals 1-3, HCWs interviewed for immune status and recent relevant illnesses in themselves or family members At Hospital 4, HCWs interviewed for polio vaccine status, immune status and recent relevant illnesses in themselves or family members Stool samples obtained from potentially exposed patients at Hospital 4 and HCWs

Additional Disease Surveillance AFP surveillance initiated for potential adverse reactions to Menactra Aseptic meningitis surveillance in Amish counties National and international notifications regarding the case

Outbreak Control Measures IPV* was offered to community members All MN Amish communities Non-Amish community members Many adults vaccinated in 1979 IPV offered to staff and patients at Hospital 4 *OPV not available in the US

Laboratory Findings Index case virus: 2.3% divergent from Sabin 1—suggestive of iVDPV Initially thought to arise from an immunocompromised healthcare source Subsequent data suggest circulation in the community prior to index case’s infection Serial stool cultures positive for polio until after successful BMT

Laboratory Findings 3/3 siblings All anti-PV1 +, negative anti-PV2, anti PV3 Stool cultures negative 4 well children ages 2-14 yrs in 2 households shedding virus Minimal contact with index household 30 HCWs and 35 patients culture negative at Hospital 4

Index Family

Epidemiological Findings No known immunodeficient persons in MN Amish communities No immunodeficient persons on staff of hospitals No international immunodeficient persons of appropriate age in medical facilities in MN No international VAPP in Shriner’s hospitals

Epidemiological Findings No Amish with GBS/polio No Amish with aseptic meningitis 9 cases of GBS in 3 years in 4 Amish counties All 4 GBS in 2005 > 45 years No illness compatible with polio in HCWs or patients at all 4 hospitals

Immunization Results 9 out of 24 families in index community accepted vaccination 31 out of 32 Amish families in nearby community which requested vaccination 9 out of 11 Amish families in another nearby community where vaccine was offered Another nearby Amish community refused

Immunization Results Other MN Amish communities 35% to 100% initiated IPV 135 staff vaccinated Hospital 4

Conclusions First identified VDPV in the US and first occurrence of VDPV transmission in a community since OPV discontinued in 2000 29th known chronically infected immunodeficient poliovirus excreter Origin unknown Virus likely circulating for approximately 2 years

Conclusions Laboratory evidence polio virus circulated in the community Index case likely infected in community No evidence of circulation beyond MN Amish

Public Health Implications Risk for transmission to communities with low vaccination coverage is high Contacts between persons in communities with low vaccination coverage pose the potential for transmission to other communities in the US, Canada, and other countries Last Polio Outbreak in the US occurred in 1979 among Amish

Public Health Implications Prevalence of chronic VDPV infection unknown iVPDV transmitted person-to-person Implications for global eradication strategies