Retrospective Characterization of Initial Peste des petits ruminants Outbreaks (2008-2012) in the Democratic Republic of the Congo.

Peste des petits ruminants (PPR) is an acute, contagious viral disease of small ruminants, goats and sheep. The Democratic Republic of the Congo (DRC) was a PPR-free country until 2007, although in 2006, scare alerts were received from the east and the southwest of the country, reporting repeated mortalities, specifically in goats. In 2008, PPR outbreaks were seen in several villages in the west, leading to structured veterinary field operations. Blood, swabs and pathological specimens consisting of tissues from lungs, spleens, lymph nodes, kidneys, livers and hearts were ethically collected from clinically infected and/or dead animals, as appropriate, in 35 districts. Epidemiological information relating to major risk factors and socio-economic impact was progressively collected, revealing the deaths of 744,527 goats, which converted to a trade value of USD 35,674,600. Samples from infected and dead animals were routinely analyzed by the Central Veterinary Laboratory at Kinshasa for diagnosis, and after official declaration of PPR outbreaks by the FAO in July 2012, selected tissue samples were sent to The Pirbright Institute, United Kingdom, for genotyping. As a result of surveys undertaken between 2008 and 2012, PPR virus (PPRV)-specific antibodies were detected in 25 locations out of 33 tested (75.7%); PPRV nucleic acid was detected in 25 locations out of 35 (71.4%); and a typical clinical picture of PPR was observed in 23 locations out of 35 (65.7%). Analysis of the partial and full genome sequences of PPR viruses (PPRVs) obtained from lymphoid tissues of dead goats collected in Tshela in the DRC in 2012 confirmed the circulation of lineage IV PPRV, showing the highest homology (99.6-100%) with the viruses circulating in the neighboring countries of Gabon, in the Aboumi outbreak in 2011, and Nigeria (99.3% homology) in 2013, although recent outbreaks in 2016 and 2018 in the western part of the DRC that borders with East Africa demonstrated circulation of lineage II and lineage III PPRV.

Large-Scale International Validation of an Indirect ELISA Based on Recombinant Nucleocapsid Protein of Rift Valley Fever Virus for the Detection of IgG Antibody in Domestic Ruminants.

Diagnostic performance of an indirect enzyme-linked immunosorbent assay (I-ELISA) based on a recombinant nucleocapsid protein (rNP) of the Rift Valley fever virus (RVFV) was validated for the detection of the IgG antibody in sheep (n = 3367), goat (n = 2632), and cattle (n = 3819) sera. Validation data sets were dichotomized according to the results of a virus neutralization test in sera obtained from RVF-endemic (Burkina Faso, Democratic Republic of Congo, Mozambique, Senegal, Uganda, and Yemen) and RVF-free countries (France, Poland, and the USA). Cut-off values were defined using the two-graph receiver operating characteristic analysis. Estimates of the diagnostic specificity of the RVFV rNP I-ELISA in animals from RVF-endemic countries ranged from 98.6% (cattle) to 99.5% (sheep) while in those originating from RVF-free countries, they ranged from 97.7% (sheep) to 98.1% (goats). Estimates of the diagnostic sensitivity in ruminants from RVF-endemic countries ranged from 90.7% (cattle) to 100% (goats). The results of this large-scale international validation study demonstrate the high diagnostic accuracy of the RVFV rNP I-ELISA. Standard incubation and inactivation procedures evaluated did not have an adverse effect on the detectable levels of the anti-RVFV IgG in ruminant sera and thus, together with recombinant antigen-based I-ELISA, provide a simple, safe, and robust diagnostic platform that can be automated and carried out outside expensive bio-containment facilities. These advantages are particularly important for less-resourced countries where there is a need to accelerate and improve RVF surveillance and research on epidemiology as well as to advance disease control measures.

African swine fever: Update on Eastern, Central and Southern Africa.

Control of African swine fever (ASF) in countries in Eastern, Central and Southern Africa (ECSA) is particularly complex owing to the presence of all three known epidemiological cycles of maintenance of the virus, namely an ancient sylvatic cycle involving the natural hosts and vectors of the disease as well as domestic cycles with and without involvement of natural vectors. While the situation is well documented in some of the countries, for others very little information is available. In spite of the unfavourable ASF situation, the pig population in the sub-region has grown exponentially in recent decades and is likely to continue to grow in response to rapid urban growth resulting in increasing demand for animal protein by populations that are no longer engaged in livestock production. Better management of ASF will be essential to permit the pig sector to reach its full potential as a supplier of high quality protein and a source of income to improve livelihoods and create wealth. No vaccine is currently available and it is likely that, in the near future, the sub-region will continue to rely on the implementation of preventive measures, based on the epidemiology of the disease, to avoid both the devastating losses that outbreaks can cause and the risk the sub-region poses to other parts of Africa and the world. The current situation in the ECSA sub-region is reviewed and gaps in knowledge are identified in order to support ongoing strategy development for managing ASF in endemic areas.

Seroprevalence of Rift Valley fever virus in cattle in the Democratic Republic of the Congo.

This study aimed at assessing the serological and virological status of Rift Valley fever virus (RVFV) in cattle from four climatically diverse zones of the Democratic Republic of the Congo (DRC). A total of 1675 sera samples collected between 2014 and 2015 from cattle without clinical manifestation of RVF infection were tested using competitive and capture enzyme ELISA to detect both IgG and IgM. RT-PCR was used for the detection of nucleic acid of RVFV. Out of the 1675 cattle sera tested, 203 were found to be IgG-positive, giving an overall true seroprevalence of 12.37% (95% CI 10.86-14.05). This seroprevalence varied between the four zones with a seroprevalence of 16.16% (95% CI 12.86-20.12), 14.70% (95% CI 11.72-18.29), 10.82% (95% CI 7.19-14.19), and 7.34% (95% CI 5.13-10.41) recorded in cattle sampled in the mountainous, humid savannah, dry savannah, and forest zones, respectively (p < 0.05, χ2 = 17.26). A higher true seroprevalence of 14.58% (95% CI 9.3-22.13) was found in animals aged 1 year compared to 10.43% (95% CI 8.12-13.30) and 13.16% (95% CI 11.19-15.42) in groups aged between 2-3 and > 3 years, respectively, although the difference was not statistically significant (p > 0.05, χ2 = 2.95). Similarly, no statistically significant difference (p > 0.05, χ2 = 0.04) was found between the sexes of the animals. Among the IgG-positive samples screened for anti-RVFV IgM, only 1.47% (3/203) was IgM-positive. One of the IgM-positive samples was positive by RT-PCR. These findings reveal country-wide distribution of RVF in the DRC for the first time.

Genetic Assessment of African Swine Fever Isolates Involved in Outbreaks in the Democratic Republic of Congo between 2005 and 2012 Reveals Co-Circulation of p72 Genotypes I, IX and XIV, Including 19 Variants.

African swine fever (ASF) is a devastating disease of domestic pigs. It is a socioeconomically important disease, initially described from Kenya, but subsequently reported in most Sub-Saharan countries. ASF spread to Europe, South America and the Caribbean through multiple introductions which were initially eradicated-except for Sardinia-followed by re­introduction into Europe in 2007. In this study of ASF within the Democratic Republic of the Congo, 62 domestic pig samples, collected between 2005-2012, were examined for viral DNA and sequencing at multiple loci: C-terminus of the B646L gene (p72 protein), central hypervariable region (CVR) of the B602L gene, and the E183L gene (p54 protein). Phylogenetic analyses identified three circulating genotypes: I (64.5% of samples), IX (32.3%), and XIV (3.2%). This is the first evidence of genotypes IX and XIV within this country. Examination of the CVR revealed high levels of intra-genotypic variation, with 19 identified variants.

A new species of Rhipicephalus (Acari: Ixodidae), a parasite of red river hogs and domestic pigs in the Democratic Republic of Congo.

A new tick species belonging to the genus Rhipicephalus Koch, 1844 (Acari: Ixodidae), namely, Rhipicephalus congolensis n. sp., is described. Males and females of this species are similar to those of Rhipicephalus complanatus Neumann, 1911 and Rhipicephalus planus Neumann, 1907, but it can be distinguished from them by a pattern of dense medium-sized punctations on the conscutum and scutum. Males of R. congolensis may be distinguished by the following characters: posterior half of the marginal groove deep with a sharp outer edge; anterior portion of the groove shallow with rounded edges; posteromedian groove distinct, long, and deep; adanal plates broadly sickle-shaped; bluntly pointed posteromedian spur on coxa I; and posterolateral spur on coxa I slightly longer or subequal to posteromedian spur. Females of R. congolensis may be distinguished by the following characters: outer edge of cervical grooves smooth and not clearly defined either by slope or punctations; genital aperture broad, bowl-shaped, and tripartite in appearance, with central flap flanked on either side by an oval depression; and posteromedian spur on coxa I tapering to its apex. R. congolensis is known only from the Democratic Republic of Congo, where the adults were collected from red river hogs, Potamochoerus porcus (L.), and domestic pigs, Sus scrofa (L.), within the dense equatorial forest in the districts of Equateur and Tshuapa, in the province of Equateur.

African swine fever virus serodiagnosis: a general review with a focus on the analyses of African serum samples.

African swine fever (ASF) is an infectious disease that causes heavy mortality in domestic pigs. At present there is no vaccine against ASF, and eradication in countries where the disease is endemic is based only on competent diagnosis programs and the sacrifice of infected animals. Due to the presence of natural attenuated strains, certain infection conditions may result in reduced mortality. In these situations, the disease can be diagnosed by detection of specific antibodies. The use of classical and validated diagnosis assays, such as ELISA and Indirect Immunofluorescence or Immunoblotting, allowed the eradication of ASF in the Iberian Peninsula in the 1990s. However, given that conventional tests include the use of antigens obtained from ASF virus (ASFV)-infected cells, they have several disadvantages, such as difficulties to achieve standardization and also the risks associated with the manipulation of live virus. Such drawbacks have led to the development of alternative and more robust systems for the production of ASFV antigens for use in anti-ASFV antibody detection systems. In the present review, we provide an update on current knowledge about antigen targets for ASFV serodiagnosis, the significant progress made in recombinant antigen production, and the refinement of ASF serological diagnostic assays. Moreover, we describe the accuracy of an ELISA developed for the serodiagnosis of ASFV in Africa. This assay is based on a novel p30 recombinant protein (p30r) obtained from an Eastern African viral isolate (Morara strain), which shares 100% amino acid sequence identity with the Georgia virus isolate. That study included the analyses of 587 field sera collected from domestic pigs and warthogs in Senegal (West Africa), the Democratic Republic of Congo (Central Africa), Mozambique (South-East Africa), and South Africa. The results revealed that the novel p30r-based ELISA allows the accurate detection of antibodies against ASFV, independently of the geographical origin of the sera.