Update on Mumps Outbreak – 2016-2017 Washington State

Chas DeBolt RN, MPH

Office of Communicable Disease Epidemiology

Vaccine Advisory Committee Quarterly Meeting

October 19, 2017

NOT FOR DISTRIBUTION

Mumps virus basics

Henle et al. (1948), Gupta et. al. (2005)

• Incubation period: 12–25 days

• Infectious period:• Up to 7 days before and 9–14 days after symptom onset

• Contact investigation:• 4 days before through 4 days after symptom onset

• Evidence of immunity:• Vaccination, titer (IgG), born before 1957, documentation of physician-diagnosed mumps

• Potential complications:• Orchitis, mastitis, meningoencephalitis, deafness

• Severity of disease increases with age

Reported mumps cases in the US, 1968–2016

Mumps in Washington, 1920 – August 9, 2017

0

5000

10000

15000

20000

19

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Nu

mb

er o

f ca

ses

Year

1967: Mumps vaccine became

available

1989: Second dose of mumps vaccine recommended for

school-aged children and

college students

1977: Mumps vaccine

recommended for routine use

Mumps outbreak cases Washington State by county 10/20/2016 through 8/9/2017County Number of cases

Benton 6

Ferry 3

Grant 45

King 312

Kitsap 2Okanogan 3

Pend Oreille 3

Pierce 62

Skagit 17

Snohomish 87

Spokane 333

Stevens 1

Thurston 6

Whatcom 4

Yakima 5

Total 889

Clallam

Grays

Harbor

Pacific

Cowlitz

Clark

Island

King

Lewis

Mason

Pierce

Skagit

Snohomish

Thurston

Whatcom

Adams

Benton

Chelan

Columbia

Franklin Garfield

GrantKittitas

Klickitat

Lincoln

Okanogan

Spokane

Walla

Walla

Whitman

Yakima

Douglas

Ferry

Stevens

Pend

Oreille

Asotin Skamania

Wahkiakum

JeffersonKitsap

San Juan

1-10 cases

11-50 cases

50-200 cases

200+ cases

0 cases

Mumps outbreak investigations by county as of 8/9/2017

Clallam

Grays

Harbor

Pacific

Cowlitz

Clark

Island

King

Lewis

Mason

Pierce

Skagit

Snohomish

Thurston

Whatcom

Adams

Benton

Chelan

Columbia

Franklin Garfield

GrantKittitas

Klickitat

Lincoln

Okanogan

Spokane

Walla

Walla

Whitman

Yakima

Douglas

Ferry

Stevens

Pend

Oreille

Asotin Skamania

Wahkiakum

JeffersonKitsap

San Juan

1-10 investigations

11-50 investigations

50-200 investigations

200+ investigations

0 investigations

* The Department of Health and local health jurisdictions also assisted with investigations for:AK, CA, FL, IL, OH, OR, and UT residents

Mumps outbreak cases by average number of new cases per day reported to DOH (includes weekends in denominator)December 2016 – August 2017

MonthAverage number of new cases per day reported to DOH

December 3.9

January 6.4

February 7.6

March 5.7

April 3.1

May 1.6

June 0.7

July 0.5

August 0.1

Mumps outbreak cases and other investigations by date of symptom onset (excludes investigations with no onset recorded)October 2017–August 2017

NOT FOR DISTRIBUTION

0

5

10

15

20

25

30

35

40

45

50

10

/29

/16

11

/5/1

6

11

/12

/16

11

/19

/16

11

/26

/16

12

/3/1

6

12

/10

/16

12

/17

/16

12

/24

/16

12

/31

/16

1/7

/17

1/1

4/1

7

1/2

1/1

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7

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/17

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2/1

8/1

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/17

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/17

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/17

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5/1

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7

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7

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/17

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7

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7

6/2

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7

7/1

/17

7/8

/17

7/1

5/1

7

7/2

2/1

7

7/2

9/1

7

8/5

/17

Nu

mb

er

of

case

s/in

vest

igat

ion

s

Onset date

Investigated, not outbreak cases

Outbreak cases

Descriptive characteristics of cases (n=889)October 2016 – August 2017

Age range N %

0-4 34 4%

5-9 104 12%

10-14 198 22%

15-19 214 24%

20-39 256 29%

40-64 80 9%

65+ 2 0%

Unknown 1 0%

School aged (5-19 years) 516 58%

Case is Marshallese N %

Yes 465 52%

No 401 45%

Unknown 23 3%

www.medical-explorer.com

Category

Total number of cases

Cases with unknown

vaccination status

Cases with vaccine

information available

Number with 2+ doses

Number with 1 dose

Number with 0 doses

Total number

UTD*

% of cases with

available vaccine

information UTD

School-aged (5-19 years) 516 35 (7%) 481 (93%) 438 27 16 438 91%

School-aged Marshallese (5-19 years)

304 29 (10%) 275 (90%) 255 12 8 255 93%

Marshallese 465 125 (27%) 340 (73%) 268 32 40 288 85%

Entire outbreak 889 229 (26%) 660 (74%) 510 82 68 574 87%

Vaccination status of casesOctober 2016 – August 2017

Orchitis rates among unvaccinated vs. vaccinated males with mumps in Washington StateOctober 2016 – August 2017

Unvaccinated Vaccinated± Unknown vaccination status

Confirmed and probable mumps outbreak cases (n=889)

Total casesNo.

of cases

Cases reporting orchitis

Rate per

1,000 cases

No.of cases

Cases reporting orchitis

Rate per

1,000 cases

No.of cases

Cases reporting orchitis

Rate per

1,000 cases

Male cases 417 31 4 129.0 286** 11 38.5 100 12 120.0

Postpubertal males* 324 24 4 166.7 205*** 10 48.8 95 12 126.3

* Age 11 and over± Documentation of one or more doses of mumps-containing vaccine

** Includes 251 cases with 2 doses, 35 cases with 1 dose***Includes 181 cases with 2 doses, 24 cases with 1 dose

Mumps outbreak cases by outbreak name and date of symptom onsetDecember 2016 – August 2017

0

2

4

6

8

10

12

14

16

18

20

10

/29

/16

11

/5/1

6

11

/12

/16

11

/19

/16

11

/26

/16

12

/3/1

6

12

/10

/16

12

/17

/16

12

/24

/16

12

/31

/16

1/7

/17

1/1

4/1

7

1/2

1/1

7

1/2

8/1

7

2/4

/17

2/1

1/1

7

2/1

8/1

7

2/2

5/1

7

3/4

/17

3/1

1/1

7

3/1

8/1

7

3/2

5/1

7

4/1

/17

4/8

/17

4/1

5/1

7

4/2

2/1

7

4/2

9/1

7

5/6

/17

5/1

3/1

7

5/2

0/1

7

5/2

7/1

7

6/3

/17

6/1

0/1

7

6/1

7/1

7

6/2

4/1

7

7/1

/17

7/8

/17

7/1

5/1

7

7/2

2/1

7

7/2

9/1

7

8/5

/17

Nu

mb

er o

f ca

ses

Onset date

Multistate MUM 2016-002

UW MUM 2017-001

We selected specimens for sequencing based on unique epi characteristics

Lack of known epi-link to the outbreak

First case identified in a given local health jurisdiction

History of travel during the likely exposure period

– Spent part of exposure period outside WA (or outside the USA)

Membership in social group or community with no previous cases, or with a high potential for spread

– Fraternity/Sorority

We also put out a request to local jurisdictions to notify us of any case they deemed to be of high interest for sequencing

When one incubation period had passed since the August 12th onset of our last case, we thought it might be our last in the outbreak

Last contagious on August 17

+

2 maximum incubation periods, or 50 days

=

“All clear date” of October 7

Three new positive have subsequently been reported:

King County – 47 year old with a connection to Kosrae

– September 9th onset

Whatcom County 6 year old that attends church regularly in British Columbia – September 14th onset

Thurston County unimmunized 13 year old (17 year old epi-linked sibling)

Two schools involved

– October 2nd onset

Outcome of sequencing:

King County case with Kosrae connection – sequencing showed the virus was identical to that seen in the large multistate outbreak

Last contagious on September 14th

+

2 maximum incubation periods, or 50 days

=

New “All clear date” of November 3rd

Then what……..?

Sequence results pending for Whatcom County case with B.C. connection and Thurston County school – aged case

Thank you.

Questions?

Chas DeBolt RN, MPH

Senior Epidemiologist for Vaccine Preventable Diseases

Office of Communicable Disease Epidemiology

Washington State Department of Health

1610 NE 150th Street

Shoreline. WA 98155

Chas.DeBolt@DOH.WA.gov

(206) 418-5431