VDU's blog: Zika virus disease

Showing posts with label Zika virus disease. Show all posts

Sunday, 19 June 2016

Colombia Zika virus report, Epidemiological Week No. 23...

The latest epidemiological report from Colombia, which includes data on Zika virus disease (ZVD; 05JUN2016-11JUN2016), has been produced by the Colombian National Institute for Health team.[1]
NOTE: While these data are from those reported the past epidemiological week, they may not be from that week. See earlier post about possible reporting lag.

Graph No.1. The cumulative curve of confirmed ZVD cases
(green circles, left-hand axis) and the change in confirmed ZVD case
numbers when compared to the preceding week's total
(green bars, right-hand axis). Data from [1].
Click on graph to enlarge.

Graph No. 1 shows that zero new laboratory confirmed cases of ZVD were reported this week-this must be an "off" week for laboratory reporting - you can see others in the above graph where the green bars sit at zero. The total still rests at 8,221 or 10% (the highest proportion reported to date) of all clinically suspected Zika virus (ZIKV) detections.

Graph No.2. The cumulative curve of suspected ZVD cases
(pink circles, left-hand axis) and the change in suspected ZVD case
numbers when compared to the preceding week's total
(red bars, right-hand axis). Data from [1].
Click on graph to enlarge.

Graph No. 2 shows the change in suspected cases. These are not laboratory confirmed. The suspected ZVD cases continue to rise in a linear fashion, adding 2,086 this week to total 85,021.

Graph No.3. The cumulative curve of confirmed ZIKV infections
(lilac circles, left-hand axis) and the change in confirmed ZIKV infection
numbers when compared to the preceding week's total
(purple bars, right-hand axis). Now added the reported umber of microcephaly cases
confirmed as ZIKV infected (yellow bars, right-hand axis). To account for adjustments
that take cases away when there is no weekly case growth, a negative
value - the y-axes now allow for negative values. Data from [1].
Click on graph to enlarge.

Graph No. 3 shows that to Epidemiological Week No. 23, 10,704 suspected (+268 compared to last week) and still 5,420 confirmed ZIKV infections (+zero-no lab results this week) have been identified in pregnant women.

As of this report, 6 (+0 from last 2 weeks) live births have been diagnosed with microcephaly/central nervous system disorders and were reported as being ZIKV positive; 81 (up from 69 last week and the highest value to date - could things be picking up pace?) other microcephaly diagnoses are now under investigation.[1] That represents 0.11% of all confirmed ZIKV positive mothers.

Graph No. 4 below focuses on just these ZIKV-positive cases and those that remain under investigation, highlighting how the investigatory total has changed each week, but has also been trending upwards since Epidemiological Week No. 14. This may be a marker of a rise in microcephaly and other congenital disorders.

Graph No.4. The change in confirmed ZIKV infection numbers
when detected in association with a microcephaly diagnosis, compared
to the preceding week's total (yellow bars, left-hand axis). Data are from [1].
Click on graph to enlarge.

It has now been 247 days, or 8 months 3 days, since ZIKV was first confirmed in Colombia on 16th October 2015.[2] Colombia is currently carrying the next biggest load of Zika virus disease cases, after Brazil.[3] Keep in mind that when talking about microcephaly - we have to think back in time to what insult or infection might have occurred in the first or second trimester (probably-still not definitive). The counts of virus occurring this week will have zero impact on what happened back then. Also keep in mind that Colombia may be reporting things different from Brazil.[5]

Brazil first reported reported positive (but unconfirmed) laboratory tests for Zika virus disease on 29th April 2015. Brazil then started to report a rise in foetal anomalies (an initial 141), in the form of microcephaly on 30th October 2015. This was 184 days - or about 6 months later.[4]

References...

Saturday, 18 June 2016

The elephant squeaked...

An interesting new paper came out from Pacheco and colleagues from Colombia's national institute of health (INS or Instituto Nacional de Salud) this week. The INS team have written up their Zika virus (ZIKV) data spanning from 9th August 2015 to 2nd April 2016.[1] ZIKV data were not being regularly collected prior to then.

For me, the main new outcome from this report is that there seem to be no adverse outcomes to babies born to mothers who were infected with symptoms suggestive of ZIKV infection, in the third trimester of their pregnancy. Phew.

I'm not surprised at the low number of ZIKV-related microcephaly diagnoses observed, because I've been following the INS's weekly reports on this which make that issue very clear. I talk a little more about that issue below.

There were quite a few other bits and pieces in this publication. I've tried to capture some of the ones I found interesting in the list below:

The time taken for health care centre ZIKV disease (ZVD) data to be reported by the INS is approximately 1.5 weeks
Elevations 2,000m above seal level are not considered a risk because they are above traditional ZIKV-mosquito habitats, but they may still harbour human cases that have travelled from lower elevations and these may be under-counted
In 2010, half (52%) of pregnancies in Colombia were unintended and condoms were used in the same proportion of sexual encounters reported by women. Any advice aimed at reducing risk of sexual transmission of ZIKV - or other sexually transmitted infectins - will need to innovate to get that message across
Two-thirds (67%) of suspected ZVD cases were reported in females. Incidence per 100,000 population was similar in children but higher in females. This may reflect more testing of, and concern among, women of child-bearing age
Most pregnancies with symptoms suggestive of ZVD were ongoing when this report came out. This supports the thinking that it is still too early to say that Colombia will not have the same ZVD-related congenital disease problems among its pregnant women that Brazil has claimedIn a subset of 1,850 pregnant women who delivered babies, 532 (29%; 16% of pregnancies were not ongoing-why was not made clear) experienced their symptoms in the first trimester, 702 (38%; 29% not ongoing) in the second and 616 (33%; 82% born at term with normal weigh; 2% at term but low weight, 8% preterm, 1% were perinatal deaths and 7% are ongoing) in the third.
Lanciotti primers were used for RT-PCR of serum samples, but they look to have been updated in this study. The names differ-1087 instead of 1086 in the cited publication by Lanciotti et al.[2], 1163 instead of 1162c, 1108-FAM instead of 1107-FAM.
It would be good to see what sequences were actually used here. Most RT-PCR testing (60% of 3,384 samples tested during this period) was on samples from pregnant women (see No. 4) and no testing of urine was discussed which is a shame because urine is reportedly a better sample for RT-PCR because the detection window can be extended beyond that of using serum alone
No antibody testing was available - that means a lot of missed opportunities to confirm suspect ZVD diagnoses
The INS mandates reporting of all symptomatic cases. I had a little hope that perhaps Colombia, because they have been good at reporting throughout this event, might have also looked at whether the "80% asymptomatic" figure from previous outbreaks still holds today. Okay - it was a teensy hope. It will need a specific study
Fever was an integral part of the INS case definition - but fever is absent in 20% to 72% of cases.[1,3] This could mean a lot of ZVD cases were not included in the analysis - with an unknown impact on linkage to microcephaly counts from Colombia
As STATNEWS reported earlier[4], the World Health Organization has indicated that Colombia is not reporting on aborted foetuses or miscarriages that might have been related to ZVD. The impact of this omission is unclear and it would be great to know more about the issues and concerns here
During this period 4 infants (born between weeks 37 and 39) were reported to have microcephaly and confirmed ZIKV infection; 1 had abnormal brain findings and 3 abnormal hearing evaluations and other findings were listed as well. However, none of the 4 mothers reported symptoms of ZVD during pregnancy. Colombia is capturing newborn issues other than head size, at least following that initial diagnosis of microcephaly being made
STORCH (syphilis, toxoplasmosis, other agents [which other?], rubella, cytomegalovirus, and herpes) screens, karyotype analysis and ZIKV virus testing of the subset of 1,850 pregnant women with suspected ZVD were the only other tests described.
Investigations into teratogenic or toxic causes of microcephaly [6] not happening - at least based on the contents of this report
Among 239 ZIKV-negative samples (another 316 were ZIKV positive-all collected within 7 days of symptom onset - 8 (3%) were positive for dengue virus and 23 (10%) for chikungunya virus

The authors conclude that women with symptoms suggesting ZVD in the 1st trimester, may start to deliver affected babies soon after the early April cut-off date that this report covers. It's now the second half of June though and we have only had 6 cases reported by Colombia.[5] This may all be because of those reporting differences and timing issues discussed above and elsewhere on VDU. We await some more discussion about precisely how that would be the case.

We should also remember that clinically suspected diagnoses in this neck of the woods can be fraught with difficulty because fever+rash can be caused by a very wide range of things - including other mosquito-borne viruses known to be co-circulating. Take those totals with a big grain of NaCl and look laboratory confirmed samples for trends. This is also bias because a lot of the Colombian laboratory focus has been on pregnant women.

Click to enlarge.

We really know very little about the incidence of ZIKV in the general population or about the proportion of confirmed ZIKV infections that have little or no disease or about the rate of microcephaly or other congenital disease outcomes from infection. These would be very useful numbers to have to help us understand different risks and they rely on an accurate denominator. By 'accurate' I mean one based on actual testing results, not one based on guesstimates and models that lean on "suspected" data. This knowledge gap equally applies across all of the epidemic countries though, not just to Colombia.

For now, the elephant in the room continues to be the subject of insufficient conversation.

References...

Sunday, 12 June 2016

Colombia Zika virus report, Epidemiological Week No. 22...

The latest epidemiological report, which includes data on Zika virus disease (ZVD; 22MAY2016-04JUN2016), has been produced by the Colombian National Institute for Health team.[1]
NOTE: While these data are from those reported the past epidemiological week, they may not be from that week. See earlier post about possible reporting lag.

Graph No. 1 shows that 639 more laboratory confirmed cases of ZVD were reported this week than last. The total now rests at 8,221 or 10% (the highest proportion reported to date) of all clinically suspected Zika virus (ZIKV) detections.

Graph No. 2 shows the change in suspected cases. These are not laboratory confirmed. The suspected ZVD cases continue to rise in a linear fashion, adding 1,572 this week to total 82,935.

Graph No. 3 shows that to Epidemiological Week No. 22, 10,436 suspected (+17 compared to last week) and 5,420 confirmed ZIKV infections (+529) have been identified in pregnant women.

As of this report, 6 (+0 from last week) live births have been diagnosed with microcephaly/central nervous system disorders and were reported as being ZIKV positive; 69 (up from 48 last week) other microcephaly diagnoses are now under investigation.[1] That represents 0.11% of all confirmed ZIKV positive mothers (as drop from last week). Graph No. 4 below focuses on just these positive cases.

It has now been 239 days, or 7 months 26 days, since ZIKV was first confirmed in Colombia on 16th October 2015.[2] Colombia is currently carrying the next biggest load of Zika virus disease cases, after Brazil.[3] Keep in mind that when talking about microcephaly - we have to think back in time to what insult or infection might have occurred in the first or second trimester (probably-still not definitive). The counts of virus occurring this week will have zero impact on what happened back then.

Brazil first reported reported positive (but unconfirmed) laboratory tests for Zika virus disease on 29th April 2015. Brazil then started to report a rise in foetal anomalies (an initial 141), in the form of microcephaly on 30th October 2015. This was 184 days - or about 6 months later.[4]

References...

Wednesday, 25 May 2016

Brazil's microcephaly and CNS disorder (M&CD) monitoring: Report No. 27, 2016-Week No. 20...

These graphs are made by me using data obtained from epidemiological week (EW) number 20's Brazil Ministry of Health microcephaly and foetal and infant microcephaly and central nervous system (CNS) disorders (M&CD) report.[1]

Brazil last reported a total of 120,161 suspected Zika virus detections some weeks back. Around one thousand of these have been portability confirmed.[2]

Suspected M&CD cases...

The total number of suspected M&CD cases increased by 89 to 7,623 this EW (compared to last).

The graph above shows the number of suspected M&CD diagnoses in Brazil up to 21-May-2016. The cumulative curve (yellow dots; left hand axis) is growing, but slowly.

This was another slower weekly rise (orange bars; right-hand axis). These bars are based on the difference in total suspected cases reported this EW compared to that reported in the last EW. This method may not reflect the diagnoses that occurred during the past EW (some may have come from days or weeks earlier), but that level of detail is not available in the MOH report.

Confirmed and discarded M&CD diagnoses...

M&CD cases under investigation decreased by 75 to 3,257 this week - the ninth consecutive decrease.

In the graph above, we can see that 114 (blue bars; right hand axis) suspected M&CD diagnoses were discarded upon closer investigation with a current total of 2,932 removed.

The rate of these resolved diagnoses (line with blue dots, left-hand axis) continues to outpace the rate of the smaller overall number of confirmed M&CD diagnoses (red dots, left-hand axis).

As of this EW, 19% of suspected M&CD diagnoses have been confirmed while 38% of suspected diagnoses have been discarded-a percentage that has increased for 16 weeks.

The cumulative number of confirmed M&CD diagnoses does continue its climb this EW, growing by 50 new diagnoses (red bars; right-hand axis) to total 1,434.

The number of these M&CD diagnoses to be confirmed with a Zika virus infection also grows (green dots; left-hand axis) by 1 new detection (green bars; right-hand axis) to 208 this EW.

Those confirmed Zika virus infections represent 15% of all confirmed M&CD diagnoses and 3% of all suspect diagnoses.

References...

Monday, 23 May 2016

Brazil's microcephaly and CNS disorder (M&CD) monitoring: Report No. 26, 2016-Week No. 19...

These graphs are made by me using data obtained from epidemiological week (EW) number 19's Brazil Ministry of Health microcephaly and foetal and infant microcephaly and central nervous system (CNS) disorders (M&CD) report.[1]

Brazil last reported a total of 120,161 suspected Zika virus detections some weeks back. Around one thousand of these have been portability confirmed.[2]

Suspected M&CD cases...

The total number of suspected M&CD cases increased by 96 to 7,534 this EW compared to last.

The graph above shows the number of suspected M&CD diagnoses in Brazil up to 14-May-2016. The cumulative curve (yellow dots; left hand axis) is growing, but slowly.

This was another slower weekly rise (orange bars; right-hand axis). These bars are based on the difference in total suspected cases reported this EW compared to that reported in the last EW. This method may not reflect the diagnoses that occurred during the past EW (some may have come from days or weeks earlier), but that level of detail is not available in the MOH report.
Confirmed and discarded M&CD diagnoses...

M&CD cases under investigation decreased by 101 to 3,332 this week - the eighth consecutive decrease. This may be occurring for a range of (guessed) reasons including:

improved capacity to address a large volume of request for clinical classification of suspect diagnoses.
streamlining the confirmation processes
retrospective application of changed head circumference definitions resulting in reductions to the number of the microcephaly diagnoses.
This aspect will not reduce the number of cases with structural brain changes that occur in the absence of a decreased head size - which are reportedly also related to Zika virus and/or other causal influences.
There is time involved in making these diagnoses because of the need for detailed ultrasound and other diagnostic investigations to identify congenital infection outcomes including intracranial calcifications, dilation of cerebral ventricles or posterior fossa changes and other issues.

In the graph above, we can see that 139 (blue bars; right hand axis) suspected M&CD diagnoses were discarded upon closer investigation with a current total of 2,818 removed.

The rate of these resolved diagnoses (line with blue dots, left-hand axis) continues to outpace the rate of the smaller overall number of confirmed M&CD diagnoses (red dots, left-hand axis).

As of this EW, 18% of suspected M&CD diagnoses have been confirmed while 37% of suspected diagnoses have been discarded-a percentage that has increased for 15 weeks.

The cumulative number of confirmed M&CD diagnoses does continue its climb this EW, growing by 58 new diagnoses (red bars; right-hand axis) to total 1,384.

The number of these M&CD diagnoses to be confirmed with a Zika virus infection also grows (green dots; left-hand axis) by 2 new detections (green bars; right-hand axis) to 207 this EW.

Those confirmed Zika virus infections represent 15% of all confirmed M&CD diagnoses and 3% of all suspect diagnoses - but these are not fair comparisons for a range of reasons I won't go on about here.

References...

Sunday, 15 May 2016

Colombia Zika virus report, Epidemiological Week No. 18...

The latest epidemiological report, which includes data on Zika virus disease (ZVD; 01MAY2016-07MAY2016), has been produced by the Colombian National Institute for Health team.[1]

Graph No.1. The cumulative curve of confirmed ZVD cases
(green circles, left-hand axis) and the change in confirmed ZVD case
numbers when compared to the preceding week's total
(green bars, right-hand axis). Data from [1].
Click on graph to enlarge.

Graph No. 1 shows that 1,116 more laboratory confirmed cases of ZVD were reported this week than last. That's the biggest weekly rise on record. The total now at 4,867 or 7% (reaching the highest proportion reported to date) of all the clinically suspected Zika virus (ZIKV) detections.

Graph No.2. The cumulative curve of suspectedZVD cases
(pink circles, left-hand axis) and the change in suspected ZVD case
numbers when compared to the preceding week's total
(red bars, right-hand axis). Data from [1].
Click on graph to enlarge.

Graph No. 2 shows the change in suspected cases. These are not laboratory confirmed. The suspected ZVD cases continue to rise in a linear fashion, adding 2,665 this week to total 71,299 suspected cases of ZVD. This is far from the biggest weekly rise suggesting the figure above may indicate more testing or improved laboratory capacity or reporting (clearing a backlog?).

Graph No.3. The cumulative curve of confirmed ZIKV infections
(lilac circles, left-hand axis) and the change in confirmed ZIKV infection
numbers when compared to the preceding week's total
(purple bars, right-hand axis). Now added the reported umber of microcephaly cases
confirmed as ZIKV infected (yellow bars, right-hand axis). To account for adjustments
that take cases away when there is no weekly case growth, a negative
value - the y-axes now allow for negative values. Data from [1].
Click on graph to enlarge.

Graph No. 3 shows that to Epidemiological Week No. 18, 11,417 suspected (-307 compared to last week) and 2,948 confirmed ZIKV infections (+941 - biggest rise to date) have been identified in pregnant women.

As of this report, 5 (same as last week) live births have been diagnosed with microcephaly/central nervous system disorders and were reported as being ZIKV positive; 43 (up from 32 last week-fourth week to increase in total number) other microcephaly diagnoses are now under investigation.[1] That represents 0.17% of all confirmed ZIKV positive mothers (down from 0.25% last week).

It has now been 210 days, or about 7 months, since ZIKV was first confirmed in Colombia on 16th October 2015.[2] Colombia is currently carrying the next biggest load of Zika virus disease cases, after Brazil.[3] Keep in mind that when talking about microcephaly - we have to think back in time to what insult or infection might have occurred in the first or second trimester. The counts of virus occurring this week will have zero impact on what happened back then.

Brazil first reported reported positive (but unconfirmed) laboratory tests for Zika virus disease on 29th April 2015. Brazil then started to report a rise in foetal anomalies (an initial 141), in the form of microcephaly on 30th October 2015. This was 184 days - or about 6 months later.[4]

References...

Wednesday, 11 May 2016

Colombia Zika virus report, Epidemiological Week No. 17...

The latest epidemiological report, which includes data on Zika virus disease (ZVD; 24APR2016-30APR2016), has been produced by the Colombian National Institute for Health team.[1]

Graph No. 1 shows that 1 fewer laboratory confirmed case of ZVD was reported this week than last. That's different. The total now at 3,751 or 5% of all the clinically suspected Zika virus (ZIKV) detections.

Graph No. 2 shows the change in suspected cases. These are not laboratory confirmed. The suspected ZVD cases continue to rise in a linear fashion, adding 2,671 this week to total 68,634 suspected cases of ZVD.

Graph No. 3 shows that to Epidemiological Week No. 17, 11,724 suspected (+418) and 2,007 confirmed ZIKV infections (-1) have been identified in pregnant women.

As of this report, 5 (an increase (+1) from last week) live births have been diagnosed with microcephaly/central nervous system disorders and were reported as being ZIKV positive; 32 (up from 26 last week) other microcephaly diagnoses are now under investigation.[1] That represents 0.25% of all confirmed ZIKV positive mothers.

It has now been 207 days, or about 7 months, since ZIKV was first confirmed in Colombia on 16th October 2015.[2] Colombia is currently carrying the next biggest load of Zika virus disease cases, after Brazil.[3]

Brazil first reported reported positive (but unconfirmed) laboratory tests for Zika virus disease on 29th April 2015. Brazil then started to report a rise in foetal anomalies (an initial 141), in the form of microcephaly on 30th October 2015. This was 184 days - or about 6 months later.[4]

References...

Sunday, 8 May 2016

Zika, twins and complexity...

The media reported yesterday on a study underway in Sao Paolo, southern Brazil.[1] The study is looking at five pairs of twins so far - each pair includes one with a diagnosis of microcephaly, and one borne completely healthy. There is no detail on whether any less externally obvious Zika virus related central nervous system (CNS) disease has been sought so far.

From the Australian twin registry website.[8]

In the case discussed in the article, the mum of one such set of twins recalled symptoms of a Zika virus-like infection early in her pregnancy.[1] As you can see in the image to the right (and read at the linked website[8]), "twins" is a pretty broad description. It isn't hard to see how even one monozygotic twin (MZ twins develop from an egg fertilized by a single sperm) that one could become infected when another wasn't. This may be informative to the Three Parent Hypothesis.[9]

With around 3 million live births a year (roughly 8,500 live births average per day; 360 an hour [11]), there is likely to be a goodly number of twins when around 1.5% to 3.4% of live births result in twins of some type.[2,3]

I'm clearly no expert in the area of obstetrics, neonatology or congenital central nervous system disorders. But this finding, certainly not the first or only disease/healthy split between twins of this sort,[4,5,6,7] is fascinating.

To me, this finding highlights how rare the microcephaly and CNS disorder outcome seems to be after a suspected Zika virus infection of a mum at some point in her pregnancy. With so many births and just 1,300 M&CD diagnoses, its clearly nothing like as simplistic as "Zika virus infection while pregnant results in microcephaly".

A visualization some of the things that may have to occur for a maternal
Zika virus infection to result in an M&CD diagnosis.
This assumes that a mother's rash/fever/joint pain illness at some
time in her pregnancy prior to delivery, was due to Zika virus and
not one of the many other possible causes of such non-specific illness.
The order of everything in the grey box - which is not an exhaustive
list - is not intended to carry any meaning.
It is to indicate that there seem to be a large range of things
that must occur in a certain order, at a certain time, at a certain
strength or for a certain period of exposure, for the final outcome of
M&CD to occur in a newborn infant, or aborted foetus.
It may be a different mix that results in different Zika virus-related
disorders - or even in M&CD in one infant compared to the next.

What is for sure though, is that sometimes release of preliminary Zika virus disease study data without more detail and discussion, can give the appearance that things are more simple than they are.

The following tweets were a result of listening to Dr Celina Turchi Martelli, of the Brazilian Ministry of Health’s Fundação Oswaldo Cruz Foundation (FIOCRUZ)-Pernambuco, Brazil.[10]

She gave a little insight into two case-control studies she is involved in, while speaking to the Cura Zika symposium hosted by The University of Pittsburgh.[10]

@AndrewALover From aroudn 38min at https://t.co/3w20ZiN6Yp

if you want to get a better sense of it all. Thoughts? pic.twitter.com/3k33UcVjpF
— Ian M Mackay, PhD (@MackayIM) May 5, 2016

Prelim case-control study results
-#Zika infection detected in 12/23 - Odds Ratio 48

-Martelli #Zika pic.twitter.com/SctPplhRHp
— Ian M Mackay, PhD (@MackayIM) May 5, 2016

In response to those, Dr Andrew Lover crunched some numbers and highlighted that those data, when viewed in isolation, suggest that a Zika virus infection alone is almost guaranteed to result in microcephaly.

@MackayIM OR of 48 = 98% probability of MC given ZIKV(+); lower CI of 5.6 = 84.8% probability. Trimesters? DENV or CHIKV co-infection?
— Andrew Lover (@AndrewALover) May 6, 2016

But that is clearly not the case. Remember that total of 1,300 confirmed M&CD diagnoses amidst 8,500 live births a day? It was very probably not the intended meaning of Dr Martelli either.

This all just exemplifies how confusing the Zika virus epidemic can be to the public, how complex finding a cause(s) to the M&CD surge will be and how much time may yet pass before we get anywhere near that goal.

It's all a bit confusing for scientists too!

References...

Saturday, 7 May 2016

Brazil's microcephaly and CNS disorder (M&CD) monitoring: Report No. 24, 2016-Week No. 17...

These graphs are made by me using data obtained from epidemiological week (EW) number 17's Brazil Ministry of Health microcephaly and foetal and infant microcephaly and central nervous system (CNS) disorders (M&CD) report.[1]

Brazil reports a total of 120,161 suspected Zika virus detections this EW.[1] Around one thousand of these have been laboratory confirmed.

Suspected M&CD cases...

The total number of suspected M&CD cases increased by 115 to 7,343 this EW.

The graph above shows the number of suspected M&CD diagnoses in Brazil up to 30-April-2016. The cumulative curve (yellow dots; left hand axis) is growing, but slowly.

This was another slower weekly rise (orange bars; right-hand axis). These bars are based on the difference in total suspected cases reported this EW compared to that reported in the last EW. This method may not reflect the diagnoses that occurred during the past EW (some may have come from days or weeks earlier), but that level of detail is not available in the MOH report.

Confirmed and discarded M&CD diagnoses...

M&CD cases under investigation decreased by 130 to 3,580 this week - the sixth consecutive decrease. This may be occurring for a range of (guessed) reasons including:

improved capacity to address a large volume of request for clinical classification of suspect diagnoses.
streamlining the confirmation processes
retrospective application of changed head circumference definitions resulting in reductions to the number of the microcephaly diagnoses.
This aspect will not reduce the number of cases with structural brain changes that occur in the absence of a decreased head size - which are reportedly also related to Zika virus and/or other causal influences.
There is time involved in making these diagnoses because of the need for detailed ultrasound and other diagnostic investigations to identify congenital infection outcomes including intracranial calcifications, dilation of cerebral ventricles or posterior fossa changes and other issues.

In the graph above, we can see that 172 (blue bars; right hand axis) suspected M&CD diagnoses were discarded upon closer investigation with a current total of 2,492 removed.

The rate of these resolved diagnoses (line with blue dots, left-hand axis) continues to outpace the rate of the smaller overall number of confirmed M&CD diagnoses (red dots, left-hand axis).

As of this EW, 17% of suspected M&CD diagnoses have been confirmed while 34% of suspected diagnoses have been discarded.

The cumulative number of M&CD diagnoses does continue its climb this EW, growing by 73 new diagnoses (red bars; right-hand axis) to total 1,271.

The number of these M&CD diagnoses to be confirmed with a Zika virus infection also grows (green dots; left-hand axis) by 9 new detections to 203 this EW (green bars; right-hand axis). Those confirmed Zika virus infections represent 16% of all confirmed M&CD diagnoses and 3% of all suspect diagnoses - but these are not fair comparisons for a range of reasons I won't go on about here.

References...

http://portalsaude.saude.gov.br/images/pdf/2016/maio/04/coes-microcefalia-informe-epi-24-se17-2016.pdf

Sunday, 1 May 2016

Colombia Zika virus report, Week No. 16...

The latest epidemiological report, which includes data on Zika virus disease (ZVD; 17APR2016-23APR2016), has been produced by the Colombian National Institute for Health team.[1]

Graph No. 1 shows that 460 new laboratory confirmed cases of ZVD reported this week. The total now at 3,752 or 6% of all the clinically suspected Zika virus (ZIKV) detections.

Graph No. 2 shows the change in suspected cases. These are not laboratory confirmed. The suspected ZVD cases continue to rise in a linear fashion, adding 3,752 this week to total 65,963 suspected cases of ZVD.

Graph No. 3 shows that to Week No. 16, 11,306 suspected (+207) and 2,008 confirmed ZIKV infections (+305) have been identified in pregnant women.

As of this report, 4 (no increase from last week) live births have been diagnosed with microcephaly/central nervous system disorders and were reported as being ZIKV positive; 26 (up from 22 last week) other microcephaly diagnoses are now under investigation.[1]

References...

http://www.ins.gov.co/boletin-epidemiologico/Boletn%20Epidemiolgico/2016%20Boletin%20epidemiologico%20semana%2016.pdf

Static pages

Sunday, 19 June 2016

Saturday, 18 June 2016

Sunday, 12 June 2016

Wednesday, 25 May 2016

Monday, 23 May 2016

Sunday, 15 May 2016

Wednesday, 11 May 2016

Sunday, 8 May 2016

Saturday, 7 May 2016

Sunday, 1 May 2016