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Ebola virus disease: obliterating a variant and stalled case decline...

We've seen the words vigilant and vigilance used widely in recent weeks, ever since we entered a "new phase" of the Ebola virus disease (EVD) battle/fight/war.

The reason for vigilance in all things to do with this campaign has become obvious as the weeks have passed; the reduction in cases has stalled.

I've very crudely drawn in some trends below. Whether you agree with them or not, it is clear that since the fast fall in confirmed cases reported between November-January, it seems to have become very difficult to stamp out the last fires of EVD. 

The phases.
(Very) rough trends in the number of EVD cases over time.
Date from World Health Organization situation reports (SitReps)
and situation summaries (SitSumms).
Click on image to enlarge.
Liberia has come the closest to completing this goal of obliterating the Makona variant of the Zaire ebolavirus (EBOV|Makona) with just 3-9 confirmed cases between World Health Organization (WHO) Situation Report (SitReps) during any of the past 7 weeks. It seems that recent cases can be traced to known transmission chains too and that means no surprise outbreaks. 

However, the people of Guinea and Sierra Leone have not quite got the messages that those in Liberia seem to have embraced (without touching!) so admirably. 

In the last WHO SitRep [1] it was noted that 39-45 unsafe burials (probably not all that occurred) occurred in a week and >40 EVD cases were identified post-mortem. This last observation means exposure of the community to virus, not getting help and treatment for ill people, and unnecessarily requiring contact tracers to play catch-up. Bad for the infected people their friends and families and the response to EVD. It doesn't have to be that way.

This paints a picture of  problems with Ebola outreach and education, communication and cooperation. Those things will keep the latest EVD "phase" chugging along. 

We do need to destroy this variant of Ebola virus by isolating it in the last human cases in each of Guinea, Liberia and Sierra Leone. Once those people recover, or regrettably die, EBOV|Makona will be gone, except for what's in lab freezers around the world and in sequence databases thanks to the efforts of a few expert research teams. Once gone from "the wild", the evolutionary clock resets back to the EBOV variants in the animals of the forest.

EBOV|Makona knows too much; it has seen too much; it has learned too much, to be allowed to "live". It has been passed through humans too many times and while there is a vanishingly small chance it will sprout wings, it is still a virus that spreads relatively easily under the right conditions and circumstances. Explosive loss of 8 litres of fluids a day provides many ways to pass along this blood/gastro virus. EBOV|Makona may also have adapted, and continues to adapt, in other ways that would mean its stay among humans becomes lengthy and its dissemination more widespread.

More bad news from an unsuccessful obliteration of EBOV|Makon-smouldering EVD in Sierra Leone and Guinea may release new case embers that drift across borders and set new fires in other countries. We don't need hundreds of cases a day for that to happen.[3] We know cases also fly with the aid of planes (not wings). And the cycle could renew. I don't think we'll see such big outbreaks of EBOV|Makona again, for reasons I laid out here, but chasing new fires is more work than stamping out the remnants of old ones. Vigilance and action. 

I think vaccines still have an important role to play in the final phase of this epidemic, even if only 3 new healthcare worker cases were noted in the past SitRep week. Vaccine given to more than just healthcare workers could be useful here, if others will accept the needle.

  • Ebola outreach
  • Education
  • Communication
  • Cooperation

Oh, and vigilance.

References..

  1. http://apps.who.int/ebola/en/ebola-situation-report/situation-reports/ebola-situation-report-18-february-2015
  2. http://newsmedicalnet.blogspot.com.au/2014/08/behind-naming-of-ebola-virusesnot-yet.html
  3. http://newsmedicalnet.blogspot.com.au/2015/02/cases-of-ebola-virus-infection-can-be.html

Avian influenza H7N9 human infection emerged 2 years ago...

Seems like only 365 days ago I wrote about H7N9 being 1 year old.

Now - it's another year later.

While we have studied, written, read and learned much, much more about this emerging respiratory virus than we have about the Middle East respiratory syndrome coronavirus - even after its 3 years among us - we are still watching a new outbreak of human H7N9 cases spread across China. 

Each year more provinces are added to the list to report human infections - more infections likely go unnoticed, unrecorded and/or unreported. Gaps in the reporting is not unexpected and not unusual. 

Each outbreak with its accompanying economic damage, financial losses, human illness and death is because of the desire to maintain a tradition, namely the consumption of freshly extinguished poultry.

We're really good at getting ourselves into pickles. And we seem to be doomed to repeat the patterns, playing catchup and never getting in front of our new and emerging infectious diseases problems. And each time we seem amazed at what we learn, but really, we learn the same thing over, and over and over again. Eventually we'll run out of infectious threats I guess. 

Or they'll run out of hosts in which to incubate in and spread from.

Happy Lunar New Year.

Guangdong sees sense among the feathers...

Guangdong province in southern China is suspending its poultry markets. All of them. From 15-Feb to 28-Feb.[1] While the closures are only for 2-weeks, this will be very important for stopping human cases of avian influenza, particularity of the H7N9 subtype, during the bustling spring period in China. 

Live poultry market closures also remove a traditional dish of fresh cooked chicken. One can be certain that no-one will die because of the substitution of frozen or factory prepared chicken for a fresh chicken, even if chefs don't succumb to the tantrums of last year and refuse to prepare dishes made from anything but fresh market-selected poultry. One can be equally certain that if the markets remain operating during the peak season for influenza virus circulation as they have been, that human infections, and deaths, due to H7N9 infections, will also continue 


Guangdong province has been a major
source of human H7N9 cases in 2015.
Some restrictions were put in place back in December 2014 [2], but that did not stop human cases of infection or deaths.

Why does this closure in Guangdong matter? 

Guangdong province has been a major source of human H7N9 cases this year, as it was in 2014. If we look at the activity under the outbreak curves, we can see the brown line of Guangdong cases has been prominent in both years, only brought under control last year after the closure of the poultry markets...although their temporary closure may have been the reason for the long tail on Outbreak #2's epidemic curve compared to Outbreak #1. Will that tailing happen again in 2015 because Guangdong's markets are only being closed for a short period? Time will tell. 

Occurring at a similar time is the change in seasons. Seasonal change towards summer, makes the survival of influenza viruses in the environment more difficult. It's hard to tease out any one main cause of the precipitous case decline; the market closures or the seasons changing or both. Because most H7N9 human cases have exposure to poultry listed among their details when they are passed along and posted by the World Health Organization, live poultry markets clearly are one major factor for human acquisition of infection. There is literature that agrees.[3,4,5]


The activity under the epidemic curves for each of the three outbreaks. Guangdong province-acquired human cases are indicated by the brown line and features in 2014 and 2015.
Having these markets close is a great achievement for stopping these unnecessary and preventable infections and deaths die to H7N9. Its a big step, a sacrifice and its social change in action. But shutting them permanently would be better.

References...

  1. http://news.xinhuanet.com/english/china/2014-02/15/c_126138118.htm
  2. http://www.thepoultrysite.com/poultrynews/33938/guangdong-restricts-poultry-markets-over-bird-flu-fears
  3. http://www.ncbi.nlm.nih.gov/pubmed/25340354
  4. http://wwwnc.cdc.gov/eid/article/20/12/14-0765_article
  5. http://jvi.asm.org/content/88/6/3423.long

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