E-DRUG: Yellow fever alert for countries with dengue
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[There are no drug options for treating anything but the symptoms of yellow fever, dengue, chikungunya or zika. There is a vaccine available for yellow fever but stocks may not be sufficient. This message explains how non-drug options must be pursued in the absence of treatment options and taken seriously. BS]
If your country does not have year-round or seasonal dengue, this
alert is NOT for you. But if it does, please take this alert
seriously.
There is a big epidemic of yellow fever (YF) going on in Angola, West
Africa, with over 1000 cases and hundreds of deaths. Cases have spread
to the Democratic Republic of the Congo, Kenya and Mauritania in
Africa and to China, the 1st ever confirmed cases and deaths from YF
in Asia.
There is no YF epidemic in any of those other 3 African countries,
yet. But it is the dengue season in them now and soon will be in
southern China. Since YF is spread by _Aedes aegypti_, one of the
mosquitoes that spread dengue (and chikungunya and Zika viruses),
there is an obvious risk. Look at how fast chikungunya and Zika have
spread across the world. But those do not kill many people (apart from
perinatal birth defects in the case of Zika). However, in the case of
YF, 20 percent of unvaccinated people die.
Of course, we have a vaccine, but world stocks of 7 million doses have
been exhausted just to protect the population of Luanda, Angola's
capital. 18 million more are needed for the rest of the country, but
only half that number will be available by the end of next month
(April 2016); 19 million are on contracts to UNICEF and could be
repurposed. Around 40 million more may be available by the end of the
year [2016], but China will need 300 million if it spreads across its
dengue-endemic provinces.
If Yellow Fever were to spread in Asia, where 2 billion are at risk in 18
dengue-affected countries, hundreds of thousands could die before YF
vaccine stocks could be boosted and delivered. Apocalyptic forecasts
of the numbers of fatalities from Ebola turned out to be wildly wrong,
and we can hope that will again be the case here, but given the way
Zika has exploded in the Western hemisphere, we can`t count on it.
One international vaccine expert, Reinaldo Martins, did a study that
showed the Brazilian vaccine could be stretched 5-fold for adults
using subcutaneous injection, and another, Tom Monath, believes
existing stocks could be stretched 10-fold without loss of potency,
and delivered more cheaply by scratch with disposable smallpox
needles. To prove this needs a field trial, which will take a few
months. But we may have time if we start now. Brazil has the capacity
to carry out a field trial if given the funding. WHO and other
international agencies such as EMA (the European Medicines Agency)
could help with that.
Then there is mosquito control. Long lasting insecticidal nets (LLIN)
have succeeded in reducing malaria in the tropics. Outdoor fogging
only gives temporary results; long lasting pyrethroids are useful for
indoor and perifocal spraying. DDT is authorized by WHO for use in an
emergency, but although legal in India may require legislation
elsewhere. Intensified vector control with active community
participation will have the advantage of reducing cases of dengue,
chikungunya and Zika and their associated costs.
Recent research indicates that Zika virus probably reached Brazil
months before it was detected, because its symptoms are similar to
those of dengue and chikungunya and did not kill anybody until a surge
in birth defects was noticed. An increase in hemorrhage and deaths
would be put down to DHF/DSS (dengue hemorrhagic fever/dengue shock
syndrome) -- the jaundice characteristic of YF does not appear in
every case and would be diagnosed as hepatitis -- so nobody would
think of testing for YF, even if they had the reagents. There will be
a delay before there is laboratory confirmation, like there was in
Angola, allowing an epidemic to take hold disastrously.
Training of vaccination and laboratory staff, collection of the
outdoor trash in which the mosquito breeds as well as it does in small
water containers indoors, and provision of bednets, other supplies and
equipment all take time, which is why it is important that
dengue-prone countries begin right away to develop a national YF
contingency plan. WHO has a blueprint for one available on request,
and there is a relevant slide show on <http://www.pitt.edu/~super1>\.
But take note: if your country does NOT have year-round or seasonal
dengue, this alert is NOT for you -- unless you plan to travel to one
that does..
--
John P. "Jack" Woodall, PhD
Co-founder & Associate Editor, ProMED-mail
[My concern is that with so many pressing demands on public health
agencies in the dengue-endemic counties -- malaria in many, Chagas
disease in some, schistosomiasis in others, hepatitis and other
enteroviral diseases in most, to mention a few -- long-range planning
and pre-outbreak preparation gets short shrift until an outbreak such
as yellow fever hits. Vaccination of 70-80 percent of the population
at potential risk is one obvious approach, but adequate supplies of
the vaccine are necessary, and trained vaccination teams must be
available for its administration. With vaccination, vector control and
avoidance, the eternal question is: Who will pay for what is needed in
the absence of a crisis? Prevention is cheaper than crisis response,
as Angola health authorities are in the process of finding out.
Gambling that yellow fever will never hit costs nothing -- until it
does. - Mod.TY]
Carinne Bruneton
Pro-med
<carinne.bruneton@gmail.com>