The role of African buffalos (syncerus caffer) in the maintenance of foot-and-mouth disease in Uganda

Abstract

BackgroundTo study the role of African buffalos (Syncerus caffer) in the maintenance of foot-and-mouth disease in Uganda, serum samples were collected from 207 African buffalos, 21 impalas (Aepyceros melampus), 1 giraffe (Giraffa camelopardalis), 1 common eland (Taurotragus oryx), 7 hartebeests (Alcelaphus buselaphus) and 5 waterbucks (Kobus ellipsiprymnus) from four major National Parks in Uganda between 2005 and 2008. Serum samples were screened to detect antibodies against foot-and-mouth disease virus (FMDV) non-structural proteins (NSP) using the Ceditest® FMDV NS ELISA. Solid Phase Blocking ELISAs (SPBE) were used to determine the serotype-specificity of antibodies against the seven serotypes of FMDV among the positive samples. Virus isolation and sequencing were undertaken to identify circulating viruses and determine relatedness between them.ResultsAmong the buffalo samples tested, 85% (95% CI = 80-90%) were positive for antibodies against FMDV non-structural proteins while one hartebeest sample out of seven (14.3%; 95% CI = -11.6-40.2%) was the only positive from 35 other wildlife samples from a variety of different species. In the buffalo, high serotype-specific antibody titres (≥ 80) were found against serotypes O (7/27 samples), SAT 1 (23/29 samples), SAT 2 (18/32 samples) and SAT 3 (16/30 samples). Among the samples titrated for antibodies against the four serotypes O, SAT 1, SAT 2 and SAT 3, 17/22 (77%; CI = 59.4-94.6%) had high titres against at least two serotypes.FMDV isolates of serotypes SAT 1 (1 sample) and SAT 2 (2 samples) were obtained from buffalo probang samples collected in Queen Elizabeth National Park (QENP) in 2007. Sequence analysis and comparison of VP1 coding sequences showed that the SAT 1 isolate belonged to topotype IV while the SAT 2 isolates belonged to different lineages within the East African topotype X.ConclusionsConsistent detection of high antibody titres in buffalos supports the view that African buffalos play an important role in the maintenance of FMDV infection within National Parks in Uganda. Both SAT 1 and SAT 2 viruses were isolated, and serological data indicate that it is also likely that FMDV serotypes O and SAT 3 may be present in the buffalo population. Detailed studies should be undertaken to define further the role of wildlife in the epidemiology of FMDV in East Africa.

Contacts and foot and mouth disease transmission from wild to domestic bovines in Africa

“…The mechanisms of transmission between sympatric buffalo and cattle in African tropical areas are still poorly understood. However empirical information (Thomson et al 2003),serological and genetic results (Vosloo et al 2002b, Ayebazibwe et al 2010 and in natura experimens (Dawe et al 1994) all suggest that foot and mouth virus regularly spills over of from buffalo reservoir to cattle. As this emblematic wild species is also a key species in savannah ecosystems, eradication of FMD from endemic areas is currently impossible, because culling or vaccination of buffalo are not an option.…”

“…The three SATs circulate in domestic and wild populations. The African buffalo has been shown to carry asymptomatic infections and excrete viral particles, while cattle show symptoms (Vosloo et al 2002a, Thomson et al 2003, Grubman and Baxt 2004, Paton et al 2009, Ayebazibwe et al 2010.…”

Intra-serotype SAT2 chimeric foot-and-mouth disease vaccine protects cattle against FMDV challenge

“…SAT1, SAT2 and SAT3, with multiple genetics and antigenic variants in different geographical regions, defined as topotypes [9,[13][14][15][16]. All three SAT serotypes are main-tained within the African buffalo populations [9,13]. The presence of large numbers of African buffalo provides a potential source of sporadic infection to domestic livestock and other wildlife species [17][18][19].…”

“…Another unique feature of FMD epidemiology in Africa is the presence of the three Southern African Territories (SAT) serotypes, i.e. SAT1, SAT2 and SAT3, with multiple genetics and antigenic variants in different geographical regions, defined as topotypes [9,[13][14][15][16]. All three SAT serotypes are main-tained within the African buffalo populations [9,13].…”

“…a cycle involving wildlife, in particular the African buffalo (Syncerus caffer), and an independent cycle maintained within domestic animals [9][10][11][12]. Another unique feature of FMD epidemiology in Africa is the presence of the three Southern African Territories (SAT) serotypes, i.e.…”