ABSTRACT
African swine fever (ASF) is a highly lethal haemorrhagic disease in domestic and wild swine that has acquired great importance in sub-Saharan Africa since 1997. ASF was first reported in Cameroon in 1982 and was detected only in Southern Cameroon (South, West, East, Northwest, Southwest, Littoral, and Centre regions) until February 2010 when suspected ASF outbreaks were reported in the North and Far North regions. We investigated those outbreaks by analysing samples that were collected from sick pigs between 2010 and 2018. We confirmed 428 positive samples by ELISA and real-time PCR and molecularly characterized 48 representative isolates. All the identified virus isolates were classified as ASFV genotype I based on the partial B646L gene (C-terminal end of VP72 gene) and the full E183L gene encoding p54 protein analysis. Furthermore, analysis of the central variable region (CVR) within the B602L gene demonstrated that there were 3 different variants of ASFV genotype I, with 19, 20, and 21 tetrameric tandem repeat sequences (TRSs), that were involved in the 2010-2018 outbreaks in Cameroon. Among them, only variant A (19 TRSs) was identical to the Cam/82 isolate found in the country during the first outbreaks in 1981-1982. This study demonstrated that the three variants of ASFV isolates involved in these outbreaks were similar to those of neighbouring countries, suggesting a movement of ASFV strains across borders. Designing common control measures in affected regions and providing a compensation programme for farmers will help reduce the incidence and spread of this disease.
Subject(s)
African Swine Fever Virus/genetics , African Swine Fever Virus/isolation & purification , African Swine Fever/virology , African Swine Fever/epidemiology , African Swine Fever Virus/classification , Animals , Cameroon/epidemiology , Disease Outbreaks , Genetic Variation , Genotype , Phylogeny , Sus scrofa , SwineABSTRACT
In May 2016, highly pathogenic avian influenza virus of the subtype A/H5N1 was detected in Cameroon in an industrial poultry farm at Mvog-Betsi, Yaoundé (Centre region), with a recorded sudden increase of deaths among chickens, and an overall mortality rate of 75%. The virus spread further and caused new outbreaks in some parts of the country. In total, 21 outbreaks were confirmed from May 2016 to March 2017 (six in the Centre, six in the West, eight in the South and one in the Adamaoua regions). This resulted in an estimated total loss of 138,252 birds (44,451 deaths due to infection and 93,801 stamped out). Only domestic birds (chickens, ducks and geese) were affected in farms as well as in poultry markets. The outbreaks occurred in three waves, the first from May to June 2016, the second in September 2016 and the last wave in March 2017. The topology of the phylogeny based on the haemagglutinin gene segment indicated that the causative H5N1 viruses fall within the genetic clade 2.3.2.1c, within the same group as the A/H5N1 viruses collected in Niger in 2015 and 2016. More importantly, the gene constellation of four representative viruses showed evidence of H5N1/H9N2 intra-clade reassortment. Additional epidemiological and genetic data from affected countries in West Africa are needed to better trace the origin, spread and evolution of A/H5N1 in Cameroon. RESEARCH HIGHLIGHTS HPAI A/H5N1 was detected in May 2016 in domestic chickens in Yaoundé-Cameroon. Twenty-one outbreaks in total were confirmed from May 2016 to March 2017. The causative H5N1 viruses fall within the genetic clade 2.3.2.1c. The viral gene constellation showed evidence of H5N1/H9N2 intra-clade reassortment.
