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Dengue: an incessant threat
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Globally, dengue fever is recognised as a growing threat
(DengueNet, 2007). The impact of a dengue epidemic can be
disastrous. In a recent dengue update from ProMED (35 – 18
September 2007), a report from Cebu Daily News (Philippines)
said, ‘Cebu City Health Department will
recommend that two districts in Cebu City be placed under a state of calamity
after dengue claimed the lives of seven children in less
than two months’.
In our region, the last major region-wide DEN-1 epidemic
struck 16 Pacific Island countries and territories (PICTs)
between 2000 and 2005 and in some of them, affected as many as
20 per cent of the population. The epidemic also had a massive
impact on their fragile economies1. |
Photo: Service Municipal
d'Hygiène de la ville de Nouméa |
The current dengue fever outbreaks reported in Cook Islands,
French Polynesia, American Samoa, Palau and Yap, as well as the
circulation of dengue viruses in a few other PICTs (as
illustrated in this bulletin), demonstrate that dengue fever
remains a threat in the region. It is also a reminder to all PICTs to stay vigilant and ensure they have effective alert and
response systems in place to control dengue fever.
It is particularly interesting that the two outbreaks in Cook
Islands and French Polynesia are due to DEN-1 virus, despite the
fact that this virus has been circulating in the region since
2000 with significant outbreaks in many PICTs, including these
two. As an individual can be infected only once by a given
dengue serotype, there must still be a population susceptible to
DEN-1 in these PICTs. It also demonstrates that no country or
territory in the Pacific is immune to dengue, as long as
susceptible populations and an appropriate vector are present.
New serotypes can also be introduced to the region by people
coming from infected countries. On 27 September
2007, Yap State (Federated States of Micronesia) reported six
confirmed DEN-2 cases through PacNet. A few DEN-2
and DEN-4 cases were also reported in Palau at the beginning of
the year The DEN-2 serotype has not circulated in the
region since 1999.
This issue starts with a summary of the dengue situation in
the Pacific region with information gathered for 2006 and up to
September 2007. Most of the information comes from PacNet and we
wish to thank the PICTs that are sharing their dengue
surveillance and outbreak reports on the list. PacNet is
definitely a good source of information for following dengue
trends and threats for the Pacific Island region, as illustrated
in the figure on the brief section pages. Nevertheless, we
believe that the information circulated on the network is not
exhaustive. We would like to therefore encourage health
authorities from all PICTs to post dengue reports on PacNet in a
timely manner. This will keep health professionals informed of
the current dengue situation over the whole region, and further
stimulate appropriate preparedness.
A number of articles describing creative and innovative
dengue fever prevention and control strategies from the region
are presented in the bulletin. French Polynesia compiled a
comprehensive report on the present DEN-1 outbreak, detailing
the epidemiological context, control strategies implemented and
prospects for improvement.
New Caledonia’s experience is also described, with two
articles listing the wide range of measures implemented to prevent a dengue fever outbreak. Their system is
sophisticated but effective, calling into play the entire
curative and preventive health care chain. They also demonstrate
the effectiveness of the thermal imaging camera (64% of imported
dengue fever cases were identified at the airport with the
camera from 1 April to 13 August 2007) that they acquired after the last DEN-1 epidemic in 2003
and in preparation for an influenza pandemic.
Though Wallis and Futuna has not reported any case of dengue
fever since May 2004 (good on them!), they sent us an
interesting report featuring a good example of the application
of the Population Geographic Information System (PopGIS) to
their entomological surveillance system (PopGIS was developed
by our colleagues in SPC’s Demography and Statistics Programme.)
They also describe the recent initiative of the Health Agency
laboratory, which began Ag NS1 identification of the dengue
fever virus. More information about this method is given below.
Australia, which suffers regular dengue outbreaks, sent us a
comprehensive report on their vector control strategies, which
are coupled with sophisticated and aggressive disease
surveillance to achieve the goal of eradication.
From the North Pacific, we have a contribution from Yap on
the ongoing Zika outbreak there. Zika is a flavivirus that is
similar to the dengue virus and is also vectored by Aedes
mosquitoes. It could therefore spread to other PICTs that have
these vectors. We have reproduced the Zika leaflet compiled by
Yap State Department of Health Services, which includes
information for clinicians and other health professionals.
In April 2007, a message was posted on PacNet noting the
false–positive results for dengue from the PanBio rapid test
kits which were observed in Fiji, Samoa and Australia. We asked
our colleagues from the Queensland Health Scientific Services
(QHSS) laboratory in Australia (L3 LabNet laboratory) to tell us
more about their experience with this test. SPC’s
laboratory specialist also gives a brief overview of the testing
methods available for dengue, including the new products
available on the market (Pentax IgG/IgM particle agglutination
test and Bio-Rad NS1 antigen strip test) and the test
validations that are being conducted on these assays to evaluate
their performance.
We present new initiatives developed by PPHSN partners SPC,
the Pasteur Institute of New Caledonia and Louis Malardé
Institute of French Polynesia to strengthen vector surveillance
and control capacity in PICTs. The project will help PICTs not
only to respond to dengue outbreaks, but also to prevent them.
It will also include a component on developing successful
community mobilisation strategies.
Finally, a selection of reference articles and information
resources is included at the end of the bulletin. The long list
of dengue articles published in Inform’ACTION illustrates the
extent of the problems that dengue fever poses in the region.
The idea of dedicating a special issue of Inform’ACTION
to
dengue arose at the last PPHSN Coordinating Body meeting, held
in March this year. It was put together in response to the
concern expressed by PICT ministers of health in the Vanuatu
Commitment (see text box in the brief section).
The bulletin includes a series of good practices and
programmes that have been successful in controlling dengue and
that could be applied in other PICTs. Some of the more
sophisticated systems described, such as the thermal imaging
camera, might be difficult to put in place in many PICTs because
of financial and human resource constraints. Nevertheless,
interested countries could still apply similar methods by using
another less costly device to measure external body temperature.
We sincerely thank the many contributors to this big 27th
issue. We hope it will provide food for thought for PPHSN
members and that it will generate new initiatives to prevent and
control dengue fever in the region.
Since this issue is a ‘special’ one, we thought it was also a
good time to make a few cosmetic changes to the layout of
Inform’ACTION. We welcome your comments in this regard, as well
as on the content – the most important part, of course!
Christelle Lepers
Surveillance information Officer
SPC
1. Singh, N.,
Kiedrzynski, T., Lepers, C. and Kamisan Benyon
E. 2005. Dengue in the Pacific – an update of the current situation.
Pacific Health Dialog 12(2):111–120.
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