This document discusses the current status of foot-and-mouth disease (FMD) as an endemic disease in mainland Southeast Asia and China. There are three serotypes (O, A, and Asia 1) present in the region, with genetic diversity existing within serotypes O and A. Serotype O is the most common and can be divided into three topotypes. While official controls on animal movement are important for combatting the transboundary spread of the disease, irregular animal movements continue to facilitate the transmission of FMD viruses between countries in the region. Strong regional cooperation is needed for effective FMD control.

1. 1
FMD CURRENT STATUS IN SOUTHEAST ASIA AND CHINA
Yu Qiu, Ronello Abila
OIE Sub-Regional Representation for South-East Asia,
c/o DLD, 69/1 Phaya Thai Road,
Ratchathewi 10400, Bangkok, Thailand
ABSTRACT
Thispaper discusses the currentstatusof FMDasanendemic diseasein China and mainlandSoutheast
Asia, its three serotypes and distinct topotypesand their genetic diversity.It also emphasizes the need
for official cross control on animal movements which is important in combatting this transboundary
animal disease.
Key words: Foot-and-Mouth Disease, FMD, serotype virus, Transboundary Animal Diseases
INTRODUCTION
FMD is endemic in China and in mainland Southeast Asia (SEA) comprising of Cambodia, Lao PDR,
Peninsular Malaysia, Myanmar, Thailand and Vietnam, with reports of regular outbreaks. The island
states comprising of Brunei Darussalam, Indonesia, the Philippines, and Singapore, as well as East
Malaysia, are recognized by OIE as FMD free countries/zones without vaccination.
Serotype O, A and Asia 1 are the only three serotypes endemic to SEA and China. Serotype O is
the most common circulating serotype with three distinct topotypes, consisting of the SEA topotype,
the ME-SA topotype and the Cathay (pig-adapted) topotype. First reported in Myanmar in 1998, the
Mya-98 strain of the SEA topotype is widely spread in this region. The ME-SA topotype, which
originate from India, can be further divided into several sublineages (also called as strains), such as
PanAsia, Ind2001 (a,b, c,and d), and Iran2001. The PanAsia strain was introduced into SEA in the late
1990s and into China in 2009/2010. Outbreaks caused by this strain continue to occur widely in this
region and have further affected South Korea,Japan, Mongolia, and Russia. Importantly, the Ind2001d
strain, indigenous in the Indian subcontinent which has further expanded to the Middle East and North
Africa during 2013 to 2014, has recently been identified in SEA for the first time in its history.
Outbreaks due to this strain were reported in Lao PDR in April/May 2015 and in Vietnam in
September/October 2015. The first FMDV strain belonging to the Cathay topotype was isolated from
pigs in Hong Kong in 1970s and shortly it became established in Hong Kong and Southern China. In
the following decades, the Cathay topotype has been confirmed in several SEA countries, including
Malaysia, the Philippines, Taiwan,Thailand and Vietnam. In the more recentyears,the Cathay topotype
is reported on a very sporadic basis in SEA, with the latest outbreak in Thailand in 2012 and Vietnam
in 2015 (Table 1).

2. 2
Table 1. FMDV strains detected in SEA and China during 2011-2015, as characterized by World
and/or Regional Laboratory for FMD.
Country Virus Lineage 2011 2012 2013 2014 2015
Cambodia Serotype O + + + + +
O/SEA/Mya98 +
O/ME-SA/PanAsia + + +
O/ME-SA/Ind2001d
O/Cathay
Serotype A + +
A/Asia/Sea97 +
China Serotype O + + + +
O/SEA/Mya98 + + + +
O/ME-SA/PanAsia + + +
O/ME-SA/Ind2001d
O/Cathay
Serotype A + + +
A/Asia/Sea97 + + +
Lao PDR Serotype O + + + + +
O/SEA/Mya98 + + + +
O/ME-SA/PanAsia + +
O/ME-SA/Ind2001d +
O/Cathay
Serotype A + +
A/Asia/Sea97 + +
Malaysia Serotype O + + + + +
O/SEA/Mya98 + + + +
O/ME-SA/PanAsia
O/ME-SA/Ind2001d
O/Cathay
Serotype A + + + +
A/Asia/Sea97 + + + +
Myanmar Serotype O + + + + +
O/SEA/Mya98 +
O/ME-SA/PanAsia
O/ME-SA/Ind2001d
O/Cathay
Serotype A +
A/Asia/Sea97 +
Thailand Serotype O + + + + +
O/SEA/Mya98 + + + + +
O/ME-SA/PanAsia + + +
O/ME-SA/Ind2001d
O/Cathay +
Serotype A + + + + +
A/Asia/Sea97 + + + + +
Viet Nam Serotype O + + + + +
O/SEA/Mya98 + +
O/ME-SA/PanAsia + + + + +
O/ME-SA/Ind2001d +
O/Cathay +
Serotype A + + + +
A/Asia/Sea97 + + + +
+: the FMDVlineage present in the country.
Note: data were based on the genotyping results from thePirbright Institute
(http://www.wrlfmd.org/fmd_genotyping/asia.html) and country reports presented at the 18th
- 22nd
Meetings of the OIE
Sub-Commission for FMD in South-East Asia and China.

3. 3
GENETIC DIVERSITY
In contrast to the various topotypes within the serotype O, the Asia topotype is the only topotype of
serotype A identified in SEA. The serotype A virus is widespread in this region, but it had never been
isolated in Myanmar until August/September 2015, whereas specific serotype A antibodies were
detected in buffalo sera collected during 2008 and 2009 from several states in Myanmar. The serotype
A isolates in Myanmar are very closely related (99.8% identity in VP1 nucleotide sequences) to the
isolates recovered in China and Russia in 2013 and those recovered in Thailand in 2014-15, suggesting
that these viruses share a common recent ancestor and that the Myanmar serotype A outbreaks unlikely
represent a new incursion of FMDV from India.
The phylogenetic analysis of serotype O and A FMDVs collected in SEA from 2012 to 2015 shows
that genetic diversity exists within both serotypes. Based on the VP1 gene, the serotype O viruses were
grouped into eight clusters, and the serotype A viruses were grouped into six clusters. Viruses of the
same cluster can often be found in various neighboring countries, suggesting significant
epidemiological links among them.
Serotype Asia 1 has not been detected in the region in recent years. It was last detected in Lao PDR
in 1999, Myanmar in 2001, Malaysia in 2005, Thailand in 1998, Cambodia in 1997, Vietnam in 2008
and China in 2009. Although initially serotype Asia 1 was suspected in two of the samples from
Cambodia in 2015, no evidence of the presence of this serotype could be found.
CONCLUSION
The free grazing system and irregular animal movement pattern are considered as significant risk
parametersin the spreadof FMD. Myanmar is generally considered asa key country in terms of regional
FMD epidemiology, due to its significant cattle population and their significant export flow into other
SEA countries and China. Thailand, Cambodia and Lao PDR are transiting countries, where cattle of
Myanmar, India or Bangladesh origin pass through before entering Malaysia, Vietnam and China.
Indeed, matching the pathways of FMD virus dissemination and animal movements in SEA reveals a
good agreement: the clustering of outbreaks in southern Thailand and northern Malaysia fits the flow
of cattle movement, which is most obvious prior to Malaysia’s religious festivals; the clustering of
outbreaks in the southern part of Cambodia and Vietnam also follows the flow of cattle movement. All
these reinforce the need for strong official controls on cross-border animal movements, as well as for
enhancing multinational cooperative measures on FMD control.