Unrecognized circulation of SAT 1 foot-and-mouth disease virus in cattle herds around Queen Elizabeth National Park in Uganda

Abstract

BackgroundFoot-and-mouth disease (FMD) is endemic in Uganda in spite of the control measures used. Various aspects of the maintenance and circulation of FMD viruses (FMDV) in Uganda are not well understood; these include the role of the African buffalo (Syncerus caffer) as a reservoir for FMDV. To better understand the epidemiology of FMD at the livestock-wildlife-interface, samples were collected from young, unvaccinated cattle from 24 pastoral herds that closely interact with wildlife around Queen Elizabeth National Park in Uganda, and analysed for evidence of FMDV infection.ResultsIn total, 37 (15 %) of 247 serum samples had detectable antibodies against FMDV non-structural proteins (NSPs) using a pan-serotypic assay. Within these 37 sera, antibody titres ≥ 80 against the structural proteins of serotypes O, SAT 1, SAT 2 and SAT 3 were detected by ELISA in 5, 7, 4 and 3 samples, respectively, while neutralizing antibodies were only detected against serotype O in 3 samples. Two FMDV isolates, with identical VP1 coding sequences, were obtained from probang samples from clinically healthy calves from the same herd and are serotype SAT 1 (topotype IV (EA-I)). Based on the VP1 coding sequences, these viruses are distinct from previous cattle and buffalo SAT 1 FMDV isolates obtained from the same area (19–30 % nucleotide difference) and from the vaccine strain (TAN/155/71) used within Uganda (26 % nucleotide difference). Eight herds had only one or a few animals with antibodies against FMDV NSPs while six herds had more substantial evidence of prior infection with FMDV. There was no evidence for exposure to FMDV in the other ten herds.ConclusionsThe two identical SAT 1 FMDV VP1 sequences are distinct from former buffalo and cattle isolates from the same area, thus, transmission between buffalo and cattle was not demonstrated. These new SAT 1 FMDV isolates differed significantly from the vaccine strain used to control Ugandan FMD outbreaks, indicating a need for vaccine matching studies. Only six herds had clear serological evidence for exposure to O and SAT 1 FMDV. Scattered presence of antibodies against FMDV in other herds may be due to the occasional introduction of animals to the area or maternal antibodies from past infection and/or vaccination.The evidence for asymptomatic FMDV infection has implications for disease control strategies in the area since this obstructs early disease detection that is based on clinical signs in FMDV infected animals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0616-1) contains supplementary material, which is available to authorized users.

Serological and phylogenetic characterization of foot and mouth disease viruses from Uganda during cross‐sectional surveillance study in cattle between 2014 and 2017

“…We demonstrated active circulation of multiple FMDV serotypes in cattle herds across different regions in Uganda during 2014–2017, which is consistent with earlier observations in the region (Mwiine et al, ; Namatovu, Tjørnehøj, et al, ). However, compared with prior reports in Uganda (Ayebazibwe, Mwiine, Tjørnehøj, et al, ; Balinda, Belsham, et al, ; Dhikusooka et al, ; Mwiine et al, ; Namatovu, Belsham, et al, ; Namatovu, Tjørnehøj, et al, ), the results reported here provide new information regarding recent circulation of FMDV in Uganda. We documented the circulation of new genetic lineages in Uganda mostly associated with serotypes O (topotype EA‐1 and EA‐2), SAT 1 (topotype I) and SAT 2 (topotypes VII and X).…”

“…The percentage of identity within this lineage was 99.7 ± 0.1%, and 99.0 ± 0.4% at the nucleotide and amino acid levels respectively. Interestingly, phylogenetic relationships were found between this lineage and previous viral strains recovered from western Uganda in 1970 (UGA‐Buff/21/70) (Lasecka‐Dykes et al, ) from an African buffalo ( Syncerus caffer ) in the Queen Elizabeth National Park (QENP), and with virus from a cattle herd located near QENP in 1999 (UGA/7/99 and UGA/3/99) (Sahle, Dwarka, Venter, & Vosloo, ) and 2011 (UGA‐116‐13/2011) (Dhikusooka et al, ). Furthermore, phylogenetic analysis classified the vaccine strain T155/71 into topotype I.…”

“…Reports from the Ugandan Ministry of Agriculture, Animal Industry and Fisheries (MAAIF) indicate that there was an increase in the number of FMD outbreaks between 2000 and 2007 as compared to the 1990s (Kasambula et al, ). Recent studies conducted in the country have shown the circulation of at least four serotypes including: O (topotype: EA‐2; strains: U24/11, and U07/11), A (topotype:G‐I; strain: U74/13), SAT 1 (topotype: IV; strain: UGA‐116‐13/2011) and SAT 2 (topotype: IV; strain: U73/13) (Ayebazibwe, Mwiine, Tjørnehøj, et al, ; Balinda, Belsham, et al, ; Dhikusooka et al, ; Mwiine et al, ; Namatovu, Tjørnehøj, et al, ). In addition, serotype SAT 3 virus was isolated from a healthy calf in Uganda though this serotype does not appear to be widely distributed (Dhikusooka et al, ).…”

“…Recent studies conducted in the country have shown the circulation of at least four serotypes including: O (topotype: EA‐2; strains: U24/11, and U07/11), A (topotype:G‐I; strain: U74/13), SAT 1 (topotype: IV; strain: UGA‐116‐13/2011) and SAT 2 (topotype: IV; strain: U73/13) (Ayebazibwe, Mwiine, Tjørnehøj, et al, ; Balinda, Belsham, et al, ; Dhikusooka et al, ; Mwiine et al, ; Namatovu, Tjørnehøj, et al, ). In addition, serotype SAT 3 virus was isolated from a healthy calf in Uganda though this serotype does not appear to be widely distributed (Dhikusooka et al, ). However, molecular characterization of FMDV is not conducted on a regular basis in Uganda (Kasambula et al, ).…”

Spatiotemporal analysis of foot-and-mouth disease outbreaks in the Republic of Kazakhstan, 1955 - 2013

“…Due to its acute, contagious nature, FMDV causes high rates of morbidity, but results in relatively low mortality in adult animals. It is an important disease from an economic perspective due to decreased productivity in food-producing animals, trade restrictions imposed on countries in which the disease is present (Pluimers, Akkerman, van der Wal, Dekker, & Bianchi, 2002;Pomeroy et al, 2015) and animal movement and trade restrictions locally during outbreaks (Dhikusooka et al, 2016). For these reasons, the World Organization for Animal Health (OIE) has developed a framework for the global control and eradication of FMD (OIE and FAO, 2012).…”