Dear all,

As everybody introduces him or herself, I would like to mention that I have
work for 8 years in the PARC project in Ethiopia, and after that in GREP
and the AU-IBAR PACE programme as sub-regional epidemiologist and I am
currently working as Livestock Team Leader at FAO Ethiopia.

I am sorry that the message has become a bit lengthy and also my excuses
for coming in quite late.

It is good to see the massive interest from various parts of the world for
PPR.

I would mainly like to contribute to the vaccination, and sero-monitoring
discussion.



*Vaccination:*

The estimated livestock population of Ethiopia includes 25.50 million sheep
of which about 75% are in the highlands of Ethiopia, while of the 22.78
million goats of which 75% are located in the pastoral lowland areas. The
large size of the small ruminant population in Ethiopia and the rates at
which these populations replace themselves place would place very high
demands on annual vaccination programs. As about 50% of a small ruminant
population is new born each year, flock immunity levels rapidly decline
after an annual vaccination programme, and therefore a strategy of repeated
annual vaccination campaigns is not likely to eradicate PPR from the small
ruminant population. Large numbers of vaccinations will still be required
in targeted programs and these vaccinations will need to be delivered in a
concise time span to achieve high flock immunity.

One of the lessons from the rinderpest campaign in Ethiopia is that if in a
particular ecosystem a very high immunity level was achieved, rinderpest
disease quickly disappeared. The virus quickly runs out of susceptible
hosts... Of course one had to be alert for reintroduction, especially after
the calf crop became susceptible again.



To achieve high immunity levels the following are crucial issues:

1.      Identifications of the various small ruminant ecosystems in the
country, although in the end most of them will be somehow connected, but
mostly trade movements are in a particular direction and movements within
pastoral system are quite predictable.

2.      Using participatory epidemiology, we assessed the PPR disease
status of a sub-population. In the case of rinderpest, participatory
disease searching was used to detect disease as well as information about
when the last outbreak was observed in that particular area. In case no
clinical rinderpest was found and the livestock keepers mentioned that the
last rinderpest outbreak was observed over three years prior to the date of
the PDS in that particular ecosystem, serology was used in carefully aged
young stock to proof absence of virus circulation. Again in the case of
rinderpest, if we could not detect rinderpest disease and the serum samples
of young unvaccinated stock were negative, we excluded the area from
vaccination (this reduced the area to be covered substantially and
consequently the veterinary service could focus resources on the areas
where rinderpest was circulating).

In Ethiopia we are trying to apply the same strategy for PPR, but one
difficulty observed already is that pastoralists in contrast to rinderpest
(where we even they even had different names for endemic rinderpest and
rinderpest outbreaks) do not have a specific name for PPR. The local name
often reflects a respiratory complex and thus includes CCPP and
pasteurellosis. The pen side test currently tested helps in identifying
whether the disease is PPR or not. In case disease is detected in the area,
a focussed well managed vaccination programme should be conducted with the
following important steps:

a.      As already clearly stated by Dr. Karim, the use of certified
vaccine is the very first step.

b.      Monitoring of the cold chain is very important in case of
thermo-labiel PPR vaccine and monitoring the time between the thermostable
vaccine leave the cold chain and use in the field is another important
factor. None of the thermostable vaccine that has left the cold chain
should ever be returned!

c.       Monitor the time between dilution of the vaccine and its use as
well as the way it was kept during that time. (during the rinderpest
campaign we instructed that this time should not exceed 30 minutes).

d.     Marking of vaccinated small ruminants and while conducting the
vaccination programme check for any unvaccinated flocks. Although not yet
tested Ethiopia will use paint to mark vaccinated animals. This will
facilitate detecting of unvaccinated flocks for three weeks to a month,
which is sufficient to achieve very high vaccination levels, especially if
the community assist in identifying these flocks.

e.      Focussing vaccination on areas with on-going disease transmission
and areas harbouring infection. It is a well-established principle that
infection with wild virus combined with vaccine-induced immunity gives very
high flock immunity levels. The highest level of immunity can be achieved
when livestock owners are suffering losses from the disease.

f.        Ideally pulsed vaccinations should take place at the time that
the young stock become susceptible, otherwise revaccination of these
populations should take place with a short time interval to ensure high
vaccination coverage

g.      An added advantage is that such a strategy will stimulate
veterinarians to become disease strategist, it will enhance information
collection and a steadily build-up of knowledge rather than veterinarians
becoming institutionalised vaccinators.

3.      Sero-surveillance and Sero-monitoring.

a.      Sero-monitoring, mainly needed to satisfy donors, will only be
helpful to prove that the vaccination programme has achieved the required
immunity level, if we are convinced that all steps described under point 2
are well monitored. If not, it will raise more questions than it answers.
In my experience it is better to use the limited manpower and transport to
perform the monitoring as described under point 2 and to detect
unvaccinated flocks, than to spend it on a random sample survey.

b.      Even at the time that vaccination is on-going in some parts of the
country sero-surveillance will assist in identifying areas that do not
require vaccination. And as stated by some of the colleagues, it is good
that the routines are established in at least the national reference
laboratory.

c.       Of course in the end, serosurveillance will be required to proof
absence of circulating virus.

Best regards

 Gijs



*Gijs van 't Klooster*

*FAO Ethiopia, Livestock Team Leader*

*P.O. Box 5536*

*Addis Ababa*

*Ethiopia*



*Mobile:   +251 (921) 329756 *

*Office:    +251 (11) 647 8888 ext 107*

*Fax:        +251 (11) 647 8800*

*e-mail:    [log in to unmask] <[log in to unmask]>*

*e-mail:  [log in to unmask] <[log in to unmask]> *

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