Confirmed Local Zika Transmissions In Florida Unlinked To Wynwood Increase To Three

[niman]

Florida has announced the fourth local case of Zika transmission which is not linked to the cluster (13 confirmed) cases in Wynwood.  Like the first three, government announcements (by offices of governor and health) maintained that active transmission was limited to Wynwood, creating confusion subsequently propagated by media reports.

The government use of the term "active transmission" is defined by close clustering, and failure to identify such clusters linked to four cases leads to the exclusion of these cases, even though each instance involves a case that has not recently traveled outside of Florida, and the four cases represent Floridians who reside in Miami-Dade (2), Broward, and Palm Beach counties.

Update:

Palm Beach County case may be epidemiologically linked to travel to Wynwood.

 

Edited August 10, 2016 by niman
Media Reports Linking Palm Beach Co to Wynwood

[niman]

The first case of local transmission was a Miami-Dade woman who was cited by the Florida Department of Health four days after confirmation.  Local media accounts featuring Miami-Dade infection control teams in her neighborhood indicated this case resided in the East Coral Gables community west of downtown Miami.  Testing of 54 contacts and neighbors failed to identify a linked Zika case, so the location of the infection of this index case was unknown and the case was classified as a local case not involving active transmission.

Edited August 9, 2016 by niman

[niman]

• One case in Miami-Dade: 54 close contacts and individuals from the community have been tested with no additional positives 

 

http://www.floridahealth.gov/newsroom/2016/08/080416-zika-update.html

[niman]

The second local Zika Florida transmission case involved a man residing in Broward County.  This case was announced a day after the index case.  Media reports which included Broward County mosquito control spraying in the cases neighborhood indicated this case resided in Fort Lauderdale just west of downtown.  Testing of 70 contacts and neighbors failed to link this case to another Zika case, and this case was also categorized as a case not involved in active transmission. 

[niman]

• One case in Broward: 70 close contacts and individuals from the community have been tested with no additional positive 

http://www.floridahealth.gov/newsroom/2016/08/080416-zika-update.html

[niman]

Confusion over the relationship of the first two cases with the cluster of cases in Wynwood began with the Florida governor's announcement on July 29 describing two more local cases (men in Miami-Dade and Broward County which had been aoounced two days earlier). The statement indicated that the number of local transmission cases had increased to four, but active transmission was limited to a one square mile area defined by the map that was included in the press release.

The CDC followed with a presser which did little to clarify the confusion.  The CDC announcement noted that "more than one" of the cases were linked to a small region within the 1 square mile transmission zone, which included Wynwood.

Edited August 9, 2016 by niman

[niman]

From Governor's July 29 press release:

Today, Governor Rick Scott announced that the Florida Department of Health (DOH) has concluded that four cases of the Zika virus are likely mosquito-borne.   DOH knows that the four cases are in Miami-Dade and Broward Counties. One of these cases involves a woman and the other three cases involve men.   At this time, DOH believes that active transmissions of the Zika virus are occurring in one small area in Miami-Dade County, just north of downtown.  The exact location is within the boundaries of the following area: NW 5th Avenue to the west, US 1 to the east, NW/NE 38th Street to the north and NW/NE 20th Street to the south.  This area is about 1 square mile and a map is below to detail the area.  This is currently the only area of the state where DOH is testing to see if there are local transmissions of Zika.  They are all active Zika cases and have not exhibited symptoms to be admitted to the hospital.

http://www.flgov.com/2016/07/29/gov-scott-with-likely-mosquito-borne-zika-cases-state-will-use-full-resources-to-protect-floridians/

 

Edited August 9, 2016 by niman

[niman]

From Florida DoH July 29 press release:

 

The Florida Department of Health has gathered enough information as part of its ongoing investigation into non-travel related cases of Zika in Miami-Dade and Broward counties to conclude that a high likelihood exists that four cases are the result of local transmission. At this time, the department believes that active transmission of the Zika virus are occurring in one small area in Miami-Dade County, just north of downtown. The exact location is within the boundaries of the following area: NW 5th Avenue to the west, US 1 to the east, NW/NE 38th Street to the north and NW/NE 20th Street to the south. This area is about 1 square mile and a map is below to detail the area.  While no mosquitoes trapped tested positive for the Zika virus, the department believes these cases were likely transmitted through infected mosquitoes in this area.

The department is actively conducting door-to-door outreach and urine sample collection in the impacted area and will share more details as they become available. 

http://www.floridahealth.gov/newsroom/2016/07/072916-local-zika.html

 

Edited August 9, 2016 by niman

[niman]

From CDC July 29 presser:

TOM FRIEDEN: The epidemiologic analysis strongly suggests that the exposure and the infection occurred around the workplace because of the connections between people who don't have other connections. So the Florida investigation identified in the course of their interviewing of patients and assessment of environments, that this location was likely to have been the source for more than one case of Zika spread locally. 

http://www.cdc.gov/media/releases/2016/t0729-zika-update.html

 

Edited August 9, 2016 by niman

[niman]

On the following Monday, Aug 1 all three agencies issued press releases citing 10 more Zika cases, all of which were in the 150 meter area centered in the 1 mile transmission zone.

The CDC presser had the most detail.  6 of the cases were asymptomatic but PCR testing of urine were Zika positive.  Four symptomatic contacts of the initial "2 or more" were positive via PCR or IgM antibodies.

The 150 meter area (subsequently described a six blocks) was located at the center of the 1 mile transmission zone).  Although the presser noted that 10 of the 12 cases were in the 150 meter area, it did not exclude the possibility that the other 2 cases were within in 1 mile area but outside of the 150 meter area.

However, the shape of the 1 square mile suggested that only the 12 cases were within that area (shape would have been distorted is the other two were within the larger zone) and the DoH press release noted that testing of neighbors and contacts of two of the cases were negative, suggesting these were the first two cases and these two cases were not linked to the Winwood area.

[niman]

From CDC Aug 1 presser

BETSY MCKAY: Hi.  Thanks very much.  I wanted to follow up on that last comment, Dr. Frieden.  You said they found -- was this everyone?  Were all 14 people found within this 150-meter area around the workplace, either at the workplace or in the community?  Was that everybody, or are there, you know, some people who may have been infected, you know, in that neighborhood but outside that 150-meter area?  And then my second question was, you mentioned that the, you know, mosquito populations aren't coming down because of possible resistance.  Do you know what insecticide or insecticides are being used? 

TOM FRIEDEN: Thank you.  and I’ll refer you to Florida for the details of those questions, but my understanding,  which should be confirmed with Florida is that 12 of the 14 infections so far diagnosed that are referred to in Governor Scott’s press release today occurred in this 150-meter area.

http://www.cdc.gov/media/releases/2016/t0801-zika-update.html

 

 

Edited August 9, 2016 by niman

[niman]

The next day, Tuesday, Aug 2, the 15th local case was announced as a local transmission outside of the 1 square mile transmission zone.  However, many were confused about the Wynwood linkage for the first 14 cases and reported the 15th case as the first local transmission not linked to the Wynwood area.

Edited August 9, 2016 by niman

[niman]

From DoH Aug 2 press release

The new non-travel related infection is located outside of the one-square mile area in Miami-Dade County where the department has identified active transmission is taking place. The investigation is on-going and the department has begun door-to-door outreach and sampling in the area of the confirmed case.

http://www.floridahealth.gov/newsroom/2016/08/080216-zika-update.html

 

[niman]

A request for clarification for the first 15 local cases in Florida produced an Aug 3 e-mail response from the Florida DoH which confirmed that only 12 of the first 15 cases were linked to the Wynwood area:

below is our daily Zika update. Not all cases are related to the one-square mile where active transmission is taking place. 12 cases are related to the one-square mile area. Investigations of two other cases led us to believe no local transmission is taking place in the area and one other investigation is on-going.

 

[niman]

The 16th lab confirmed local case was one of the 26 contacts of the two index cases in Wynwood.  This case increased the number linked to Wynwood to 13 and highlighted the extremely high attack rate in contacts or nearby residents.

The above case was the 5th contact confirmed out of the 26 tested.  At least one of the five was confirmed with an IgM antibody test which followed a negative PCR test.  The negative PCR test(s) indicated one or more of the symptomatic contacts had already cleared most of the virus when the serum/urine sample was collected, highlighting the limitations for the PCR test(s).  Moreover, the data suggested at least some of the contacts had been infected in June.

These data also suggested that the attack rate for nearby residents might have been higher than the 6/52 positives for urine samples from asymptomatic cases.  Some of the 46 negatives may have also been infected at an earlier date and would have tested positive only on an IgM antibody test, but there was no indication that these residents were also tested for antibodies (at least two family members of one of the positives tested negative on the urine PCR test).  

Similarly, the 52 samples would represent a small subset of nearby residents, (as well as others who may have visited the area in June or July).

Thus, the high detection rates in nearby residents or contacts suggested the number locally infected was markedly higher than the 13 confirmed cases.

Edited August 9, 2016 by niman

[niman]

The 17th case is a Palm Beach county resident.  Although the case had traveled to Miami-Dade, the press release failed to note if travel to Wynwood was included.

However, the Palm Beach case was the 4th local transmission case (the 4 were from 3 different counties) that was not reported to be linked to Wynwood, suggesting that local transmission by mosquitoes in Florida is widespread.

Edited August 9, 2016 by niman

[niman]

1 hour ago, niman said:

The 17th case is a Palm Beach county resident.  Although the case had traveled to Miami-Dade, the press release failed to note if travel to Wynwood was included.

However, the Palm Beach case was the 4th local transmission case (the 4 were from 3 different counties) that was not reported to be linked to Wynwood, suggesting that local transmission by mosquitoes in Florida is widespread.

Bradford said it was his understanding that the patient regularly worked in and near Wynwood, a popular arts district in Miami that state health department officials believe is the only area with active local transmission of the virus.

http://www.palmbeachpost.com/news/news/local/official-believes-low-potential-for-active-zika-in/nsCjL/