Published Date: 2008-10-17 21:00:33
Subject: PRO/AH/EDR> Peste des petits ruminants - Morocco (08): genotyping
Archive Number: 20081017.3290
PESTE DES PETITS RUMINANTS - MOROCCO (08): PPRV LINEAGE IV, GENOTYPING
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Date: Fri 17 Oct 2008
From: Genevieve Libeau
<genevieve.libeau@cirad.fr>
Re: Peste des petits ruminants - Morocco (07): OIE, PPRV lineage IV
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To answer your comment "Information on the further genotyping of the
Moroccan isolate and its relatedness to other lineage IV strains will
be helpful", we have sequenced up to 6 viral isolates from Morocco
and all these strains are of course from lineage IV but showing some
differences in the N genomic amplified fragment confirmed in the F
fragment. Preliminary results of the PPR N gene are indicative of the
virus being very close to the Saudi-Arabia and the Iran strains,
which make a cluster inside lineage IV. We envisage to study a number
of different strains isolated in Morocco to have an idea of the
mutation rate in this particular virus. It is urgent now to have a
more recent picture of the actual distribution of the lineages which
have shifted during the past decade.
--
Genevieve Libeau
OIE/FAO reference laboratory for PPR
Biological Systems Department - CIRAD
Control of Exotic and Emerging Animal Diseases (UPR15)
TA A-15/G Campus Int. Baillarguet
34398 Montpellier Cedex 5
FRANCE
<genevieve.libeau@cirad.fr>
[We are very grateful to Dr Libeau for kindly forwarding the above
information. The availability of such data demonstrates
the essentialness of reference laboratories and the importance of
submitting samples to them.
It will be interesting to note if and when consignments of live small
ruminants have been imported to Morocco from Middle-Eastern
countries, during recent years. The scale and rapidity of the
epizootic, reportedly spreading throughout Morocco since June 2008,
is rather puzzling; PPR would, in most cases, spread directly by
means of infected animals and (in difference with FMD) not by other,
indirect routes. How did this happen in Morocco? Could a wide-scale
dissemination of imported animals taken place? Could the initial
introduction have occurred earlier than the point in time mentioned
in the official report, remaining undetectable for some time? Have
neighbouring countries remained totally free of PPR in spite of the
explosive spread in Morocco?
Another unusual aspect of this epizootic is the apparent higher
pathogenicity of the pathogen for sheep than for goats, as shown by
their high case fatality (see further); this, in contrast to
accumulated experience in other countries, where the clinical disease
seems to be more severe in goats. However, this apparent high case
fatality may camouflage a high rate of undetected, subclinical
infections in sheep; an interesting subject for study.
The following data have been summed-up from the 9 Moroccan reports
submitted to the OIE so far (total numbers as of 14 Oct 2008; see
<http://www.oie.int/wahid-prod/public.php?page=event_summary&reportid=7212>):
Total outbreaks: 244
Total animals affected:
Species/ Susceptible/ Cases/ Deaths
Goats/ 3087/ 626/ 197
Sheep/ 40 574/ 4802/ 2321
Outbreak statistics
Species/ Apparent morbidity rate/ Apparent mortality rate/ Apparent
case fatality
Goats/ 20.28 percent/ 6.38 percent/ 31.47 percent
Sheep/ 11.83 percent/ 5.72 percent/ 48.33 percent
Surveillance for PPR deserves to be enhanced in all African and Asian
countries; alertness is justified elsewhere as well. PPR eradication,
when detected, seems to be a complex task, leading to the need for
mass vaccinations. The homologous, live attenuated PPR vaccine is
commercially available and found efficacious when adequately and
systematically applied. For details, see
<http://oie.int/eng/normes/mmanual/2008/pdf/2.07.11_PPR.pdf>.
PPR is not zoonotic. - Mod.AS]