Genetic variation among African swine fever genotype II viruses, eastern and central Europe.

African swine fever virus (ASFV) was first reported in eastern Europe/Eurasia in 2007. Continued spread of ASFV has placed central European countries at risk, and in 2014, ASFV was detected in Lithuania and Poland. Sequencing showed the isolates are identical to a 2013 ASFV from Belarus but differ from ASFV isolated in Georgia in 2007.

Potential use of oral fluid samples for serological diagnosis of African swine fever.

African swine fever (ASF) is a complex, highly lethal, notifiable disease of swine. ASF is wide-spread in sub-Saharan Africa and East European countries and there is presently a great risk of spread to neighboring countries. Since there is no vaccine for ASF virus (ASFV), control is based on rapid and early detection of the disease via surveillance. This approach requires collecting blood samples from large number of animals. Laborious and expensive of itself, this process also presents an additional risk because ASFV is present at high concentrations in the blood. The objective of this study was to initiate studies into the potential use of oral fluid as an alternative to serum for ASF diagnosis, for latter studying its possible use in surveillance and control programs. To this end, oral fluid samples collected at different times post infection from eight pigs experimentally inoculated with an attenuated ASFV were assayed using modified protocols of the two validated serological techniques, the enzyme-immune-liked assay (ELISA) and immunoperoxidase technique (IPT). Antibodies against ASFV were detected in oral fluid samples of all animals from early post infection through the end of the experiment by ELISA and IPT. These results confirmed the presence of ASFV antibodies in swine oral fluids samples, the possibility of an oral fluid-based approach in ASF diagnosis and, potentially in ASF surveillance.

African swine fever virus p72 genotype IX in domestic pigs, Congo, 2009.

African swine fever virus p72 genotype IX, associated with outbreaks in eastern Africa, is cocirculating in the Republic of the Congo with West African genotype I. Data suggest that viruses from eastern Africa are moving into western Africa, increasing the threat of outbreaks caused by novel viruses in this region.

African swine fever viruses with two different genotypes, both of which occur in domestic pigs, are associated with ticks and adult warthogs, respectively, at a single geographical site.

The role of the ancestral sylvatic cycle of the African swine fever virus (ASFV) is not well understood in the endemic areas of eastern Africa. We therefore analysed the ASF infection status on samples collected from 51 free-ranging warthogs (Phacocherus africanus) and 1576 Ornithodorus porcinus ticks from 26 independent warthog burrows at a single ranch in Kenya. Abattoir samples from 83 domestic pigs without clinical symptoms, originating from specific locations with no recent reported ASF outbreaks were included in this study. All samples were derived from areas of central Kenya, where ASF outbreaks have been reported in the past. Infection with ASFV was confirmed in 22 % of O. porcinus pools, 3.22 % of adult warthog serum samples and 49 % of domestic pig serum samples by using p72-based PCR. All of the warthog sera were positive for anti-ASFV antibodies, investigated by using ELISA, but none of the domestic pig sera were positive. Twenty O. porcinus-, 12 domestic pig- and three warthog-derived viruses were genotyped at four polymorphic loci. The ASFV isolates from ticks and domestic pigs clustered within p72 genotype X. By contrast, ASF viruses genotyped directly from warthog sera, at same locality as the tick isolates, were within p72 genotype IX and genetically similar to viruses causing recent ASF outbreaks in Kenya and Uganda. This represents the first report of the co-existence of different ASFV genotypes in warthog burrow-associated ticks and adult wild warthogs. The data from this and earlier studies suggest transfer of viruses of at least two different p72 genotypes, from wild to domestic pigs in East Africa.