EuFMD OS20

1. www.eposterboards.com
Long-believed to be a truly “African” disease, occasionally affecting the African
neighbourhood in southern Europe (Spain, Portugal, Italy) and -in the seventies- a
decade-long incursion into a number of Caribbean islands (and Brasil), ASF
embarked on an unprecedented invasion of the (rest of the) world around 2006,
with a first introduction reported well outside its usual geographical range in the
Caucasus, in Georgia in 2007.
At the time, the ASF new lineage (genotype) II “Georgia 1/2007 strain” had been
traced back to strains encountered in Madagascar, Mozambique and Zambia
mostly [1].
Ever since, the new Georgia strain has spread throughout western Europe,
central and eastern Europe, Eurasia, Russia and eventually and inevitably South-
East and East Asia, with the major impact being felt in China, the world’s premier
pork producer. Recorded for the first time in China in August 2018, the disease
has now spread to all mainland provinces and several million pigs have been
culled in an effort to halt its spread. Industry estimates suggest 150–200 million
pigs (30% of the Chinese population) had been infected by mid-2019, while some
press reports indicate that once under-recording is considered the figure may be
as high as 50–70% [2].
Meanwhile, in Africa, life-with-the-disease went on as usual. Generally regarded
as either endemic or frequently, but mildly epizootic and isolated, ASF is deemed
a poor candidate for eradication given the absence of a vaccine and the existence
of numerous wildlife reservoirs, as elsewhere in the world. Think of warthogs,
bush pigs, wild boar,… Moreover, in parts of eastern, central and southern Africa
ASF is also vector-transmitted, i.e. tick borne (Ornithodoros spp.). Where
possible, but often impossible to adopt, biosecurity is the word.
Introduction
The OIE World Animal Health Information System or WAHIS collates information
provided by the Member (and non-member) Countries and Territories of the OIE
on all aspects of animal health, through immediate notifications (exceptional
outbreaks of OIE listed and emerging diseases), six-monthly reports (covering all
listed diseases) and annual reports with additional information on e.g. animal
populations or laboratory capacity.
Methods
Discussion (continued)
References
[1] Rowlands, Rebecca & Michaud, Vincent & Heath, Livio & Hutchings, Geoff & Oura, Chris & Vosloo, Wilna
& Dwarka, Rahana & Onashvili, Tinatin & Albina, Emmanuel & Dixon, Linda. (2009). African Swine Fever
Virus Isolate, Georgia, 2007. Emerging infectious diseases. 14. 1870-4. 10.3201/eid1412.080591.
[2] Mason-D’Croz, D., Bogard, J.R., Herrero, M. et al. Modelling the global economic consequences of a
major African swine fever outbreak in China. Nat Food 1, 221–228 (2020). https://doi.org/10.1038/s43016-
020-0057-2
[3] Penrith, Mary-Louise, Duarte Bastos, Armanda, Etter, Eic M.C. & Beltrán-Alcrudo, Daniel (2019).
Epidemiology of African swine fever in Africa today: Sylvatic cycle versus socio‐economic imperatives.
Transbound Emerg Dis. 2019;66:672–686. DOI: 10.1111/tbed.13117
This poster is based on a website blog, published on 6 September 2020 and accessible here :
https://rr-africa.oie.int/en/news/an-analysis-of-15-years-of-wahis-data/ The author acknowledges
the considerable support received from Dr Mary-Louise Penrith in interpreting some of the data
generated by WAHIS and providing relevant literature to support these interpretations.
Table 1. Countries submitting immediate notifications (IN) and number of IN (2005 – 2020)
Figure 2. Reasons for submitting an immediate notification (IN) through WAHIS
Figure 1. Immediate notifications (three-year rolling average)
Figure 4. Backyard pig raising in São Tomé and Principe. Picture © P. Bastiaensen (2002).
IS AFRICAN SWINE FEVER RETURNING TO AFRICA ?
A back-of-the-envelope analysis of 15 years of WAHIS data
P. Bastiaensen
A much simpler explanation – but speculative given the absence of trustworthy
and/or updated census data – is an increase in smallholder farming of pigs
across the continent. WAHIS population data for (most of) the countries that
reported ASF over the years indicate an average 4.5% annual increase in
‘suids’, with exceptionally high growth (in absolute numbers and percentage-
wise) in countries such as Chad, Malawi and Senegal (upward from 500% over
a ten-year period 2007/2008 – 2017/2018).
In essence, if ASF outbreaks reported to WAHIS are merely the tip of the
iceberg, then maybe the iceberg just got bigger.
Discussion
Whilst WAHIS data may not readily explain the motivation behind
reporting one or several outbreaks to the OIE, the trend is
unmistakeably upwards, even in countries where ASF is regarded
endemic, common and is usually not reported, unless through six-
monthly reports.
However, when assessing the number of outbreaks reported
through six-monthly reports (i.e. most often reflecting an endemic
situation) a different picture emerges, but arguably dominated by a
few (often smaller) countries consistently reporting high numbers of
outbreaks, e.g. Benin, Togo, Cameroon, the Democratic Republic of
Congo (DRC), Rwanda, reporting on average between 20 and 46
outbreaks per year, out of a total number of outbreaks across the
continent of approximately 220 outbreaks per year.
So is ASF on its way home after a successful world tour ? Is the
increase in highly lethal ASF outbreaks an indication that African
pigs or -at least- acclimatised domestic pig species are having a
hard time when confronted with the Georgia strain, pointing to
renewed introductions of the virus from outside Africa ?
For one, WAHIS data do not seem to indicate a change in case
fatality rates, due to a more virulent virus strain, the case fatality
rate in most reported notifications (58%) since 2006 already being
higher than 95%.
Also genotype II, linked to the Georgia strain, in a 2018 Africa
review by Penrith et al. [3] is still only being reported in the initial
countries-of-origin, i.e. Madagascar, Mozambique, Tanzania,
Zambia, Zimbabwe, along with Mauritius (2007 – 2008 outbreaks).
World Organisation for Animal Health
Country IN
Benin 1
Burkina Faso 1
Burundi 1
Cabo Verde 1
Central African Rep. 2
Chad 3
Côte d’Ivoire 3
Kenya 5
Mali 1
-
1,0
2,0
3,0
4,0
5,0
6,0
7,0
86%
12%
2%
Recurrence of a listed disease
First occurrence of a listed disease
Unexpected change in the distribution or increase in morbidity or mortality of a listed disease
WAHIS-based data since its inception in 2005 indicate that “exceptional
epidemiological events” related to ASF, i.e. mostly outbreaks, have been reported
at a consistent, low rate, until 2017 – 2018, when the number of such “immediate
notifications” started to increase, pointing to a higher number of outbreaks of an
epizootic nature, either in new territories, i.e. within countries or introduced into
hitherto free countries.
This year alone, by August 8th, 5 countries have reported ASF by means of
immediate notifications : Sierra Leone, South Africa, Namibia, Nigeria and
Zambia. If the trend for 2020 persists, 2020 will have the highest number of
outbreaks on record, in Africa, since 2005 when WAHIS was launched.
Over the years, 43 outbreaks warranting an immediate notification have been
reported to the OIE (table 1). Since then, 86% of immediate notification were
justified – as per OIE regulations – as recurrences of a listed disease, previously
reported to the OIE and 12% as a first occurrence (pie chart 1).
Results
Country IN
Mauritius 1
Namibia 3
Nigeria 3
Sierra Leone 1
South Africa 7
Tanzania 2
Zambia 5
Zimbabwe 3
Map 1. Map of countries reporting ASF
through immediate notifications to the
OIE (WAHIS) since 2005. Circled are
Cabo Verde (west) and Mauritius (east).