Published Date: 2011-08-25 20:21:27
Subject: PRO/AH/EDR> West Nile virus - Eurasia (08): Greece, human, equine
Archive Number: 20110825.2595

WEST NILE VIRUS - EURASIA (08): GREECE, HUMAN, EQUINE
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Date: Thu 25 Aug 2011
Source: Eurosurveillance [edited]
http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19951


Ongoing outbreak of West Nile virus infection in humans, Greece, July
- August 2011. [Reported by: K Danis (<daniscosta@ yahoo.com>)1, A
Papa, E Papanikolaou, G Dougas, I Terzaki, A Baka, G Vrioni, V
Kapsimali, A Tsakris, A Kansouzidou, S Tsiodras, N Vakalis, S Bonovas,
J Kremastinou]
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Abstract:

Between 16 Jul and 21 Aug 2011, 31 cases of West Nile neuroinvasive
disease were reported from 4 regions in Greece. Of these, 17 occurred
in districts that had not been affected in 2010. The reoccurrence of
human cases in 2 consecutive years (following the large 2010 outbreak)
and the spread of the virus in new areas suggest that West Nile virus
is established in Greece, and its transmission may continue to occur
in the future.

Background:

Since July 2011, an outbreak of West Nile virus (WNV) infection has
been ongoing in regions in Greece that had already been affected in
2010 and in regions that had never reported human cases before. During
2010, Greece experienced the 2nd largest outbreak of WNV infections in
Europe since the one that had occurred in Romania in 1996. Overall,
262 cases of WNV infection in humans were notified mainly in northern
Greece. In the Central Macedonia region, all 7 districts had reported
cases, and in the adjacent Thessalia region, one of the 4 districts
was affected. Among reported cases, 197 presented with WNND, and 33 of
these died, indicating a case fatality rate of 17 per cent among WNND
cases. WNV lineage 2 sequences were obtained from 3 pools of _Culex_
mosquitoes (strain Nea Santa-Greece-2010), from 2 blood donors and
from wild birds. This was the 1st time that WNV infection was
documented in humans in Greece, although serosurveys in the early
1960's, 1980's and 2007 identified WNV antibodies in approximately one
per cent of the human population, suggesting that WNV, or a related
flavivirus, was circulating in Greece.

Following the large WNV outbreak in 2010, WNV human infections are
notified in Greece for a 2nd consecutive year. As of 21 Aug [2011], 31
WNND were reported from 4 regions in Greece. The temporal distribution
of cases shows that the 1st human cases in 2011 occurred approximately
2 weeks later compared to 2010.

Comparing the magnitude of the current outbreak [2011] in Central
Macedonia to the outbreak in the previous year, the current one
remains lower to date, suggesting decreased or delayed WNV
transmission in humans. Due to the high visibility of the 2010
outbreak and the subsequent raised awareness to the infection among
physicians, it is unlikely to be due to delayed recognition of the
disease or under-reporting. However, as this is an ongoing outbreak,
the number of 2011 cases corresponding to previous weeks may increase
as more cases are confirmed retrospectively.

Regarding equidae, 5 horses from East Attiki presented with clinical
WNV disease manifestation, as well as one horse from Serres (Central
Macedonia) with antibodies against WNV that demonstrated a recent
infection (IgM positive). The 1st 2 cases in horses were identified
before human cases had been reported in Attiki and thus functioned as
an early warning signal.

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Evidence of West Nile virus circulation in Greece in sentinel
chickens was reported on 4 Aug 2011 (see ProMED-mail archive no.
20110805.2359), and now there are human and equine cases.
Unfortunately, there are cases in areas that were not affected by the
WNV outbreak last year (2010).

A HealthMap/ProMED-mail map of Greece can be accessed at
http://healthmap.org/r/01Pm. - Mod.TY]

See Also