Abstracts Page 4 - RVFv & CCHF Senegal

Longitudinal Survey and Molecular Detection of Rift Valley Fever Virus in Small Ruminants in Senegal

Marie Cicille Ba Gahn1*, Gorgui Diouf1, Ndjibouyé Cissé1, Moussa Fall1, Gaye Laye Diop1, Ardiouma Faye1, Mame Thierno Bakhoum1, Mamadou Lamine Djiba1, Corrie Brown2, Faburay Bonto3,4, Modou Moustapha Lo1, and Assane Gueye Fall1

1 Institut Sénégalais de Recherches Agricoles, Laboratoire National de l’Elevage et de Recherches Vétérinaires (ISRA-LNERV), Dakar-Hann BP 2057, Senegal

2 LifeStock International, Athens, GA, USA

3 Foreign Animal Disease Diagnostic Laboratory, National Veterinary Services Laboratories, National Bio and Agro-Defense Facility, United State Department of Agriculture, Manhattan, KS 66505, USA

4 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY 11957, USA

*Corresponding author – mariececille.gahn@gmail.com

Background. Rift Valley fever (RVF) is classified among priority emerging diseases monitoring in Senegal. Recent human cases and heightened viral activity have been observed in Mauritania and Senegal. Prior cross-sectional studies in Senegal identified high-risk areas, prompting the initiation of a longitudinal survey. This study aims to assess the spatio-temporal infection of RVF virus (RVFV) transmission across Senegal.

Method. A longitudinal study was implemented in four regions of Senegal (central: Koumpentoum, eastern: Kidira, southeastern: Velingara, and northern: Saint-Louis) to monitor Rift Valley fever virus circulation and spread. From October 2023, 35-45 seronegative animals per location were monitored bimonthly using IgG and IgM antibodies detection methods. Mosquitoes were trapped using CDC light traps for two consecutive nights at each study site. In addition, viral RNA detection by RT-qPCR wqs performed on whole blood from seroconverted animals and captured mosquito vectors.

Results. This survey revealed low IgG seroconversion rate of 2.44% (4/164), with one seroconverted animal in each locality. There was an absence of IgM antibodies. Viral RNA was not detected in seroconverted animals. A total of 19,598 mosquitoes belonging to 35 species were captured. The majority of mosquitoes were captured during rainy season (52.74%) and mostly were species from genus Anopheles (51.34%). RVF vectors represented 20.09% of the total mosquito population, viral RNA was detected in 5.49% (14/255) of the tested pools mostly collected during the wet season in the south-east of the country.

Conclusion. The observed low abundance of vector species appears to correlate with the low percentage of RVF virus-infected animals during this period.

Longitudinal Survey and Molecular Detection of Crimean-Congo Hemorrhagic Fever Virus in Small Ruminants in Senegal

Marie Cicille Ba Gahn¹*, Gorgui Diouf¹, Ndjibouyé Cissé¹, Moussa Fall¹, Gaye Laye Diop¹, Ardiouma Faye¹, Mame Thierno Bakhoum¹, Mamadou Lamine Djiba¹, Corrie Brown², Faburay Bonto³,4, Modou Moustapha Lo¹, and Assane Gueye Fall¹

1 Institut Sénégalais de Recherches Agricoles, Laboratoire National de l’Elevage et de Recherches Vétérinaires (ISRA-LNERV), Dakar-Hann BP 2057, Senegal

2 LifeStock International, Athens, GA, USA

3 Foreign Animal Disease Diagnostic Laboratory, National Veterinary Services Laboratories, National Bio and Agro-Defense Facility, United State Department of Agriculture, Manhattan, KS 66505, USA

4 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY 11957, USA

*Corresponding author: mariececille.gahn@gmail.com

Background: Crimean-Congo Hemorrhagic Fever (CCHF) is an emerging tick-borne zoonosis, with recent human cases reported in Senegal. Transhumance and commercial livestock movement suggest a high potential for the arbovirus's emergence and spread. A previous cross-sectional study in Senegal identified high-risk areas, motivating the setup of a longitudinal survey on these areas. This study aimed to estimate the spatio-temporal infection of CCHFV in diverse areas.

Methods: A longitudinal survey targeting 35 to 45 initially seronegative animals per location identified as high-risk areas has been carried out since October 2023 in the center (Koumpentoum), East (Kidira), South-east (Velingara), and North (Saint-Louis) of Senegal. Bi-monthly, whole blood and tick samples were taken. Serological and viral detection were determined; ticks were identified and pooled by species. 

Results: During the first year of the study, results showed an overall seroconversion rate of 7.32% (12/164). Seroconversion rates of 17.07%, 6.52%, 2,77% and 2,43% were found respectively in the north, center, South-east and east locations. Infection was highest during the periods May-June and September-October. CCHFV RNA was detected in 58.33% (7/12) of seroconverted animals and 21.48% (113/526) tick pools. Tick pools consisted predominantly of Rhipicephalus evertsi evertsi. CCHFV vectors represented 39.65% of the 4201 ticks collected and the most common species are Rhipicephalus evertsi evertsi (35,15%). Ecological indices indicated a highest tick abundance in east and more diversity of species in the center of the country.

Conclusion: These findings highlight CCHF risk in the north, correlating with species richness and tick infection, although results found no link between seroconversion and viral detection in vectors in the south-east.

Large-scale Serological Survey of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Small Ruminants in Senegal

Marie Cicille Ba Gahn1*, Gorgui Diouf1, Ndjibouyé Cissé1, Mamadou Ciss1, Marion Bordier2, Mbengué Ndiaye1, Mame Thierno Bakhoum1, Mamadou Lamine Djiba1, Corrie Brown3, Faburay Bonto4,5, Assane Gueye Fall1, and Modou Moustapha Lo1

1 Institut Sénégalais de Recherches Agricoles, Laboratoire National de l’Elevage et de Recherches Vétérinaires (ISRA-LNERV), Dakar-Hann BP 2057, Senegal

2 Centre de Coopération Internationale en Recherche Agronomique pour le Developpement (CIRAD), UMR ASTRE, F-34398 Montpellier, France

3 LifeStock International, Athens, GA, USA

4 Foreign Animal Disease Diagnostic Laboratory, National Veterinary Services Laboratories, National Bio and Agro-defense Facility, United States Department of Agriculture, Manhattan, Kansas, USA

5 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY 11957, USA

*Corresponding author – mariececille.gahn@gmail.com

Background. Crimean-Congo hemorrhagic fever (CCHF) and Rift valley fever (RVF) are among the list of emerging zoonotic diseases that require special attention and priority. Repeated epidemic episodes and sporadic cases of CCHF and RVF in Senegal motivated this study describing a national cross-sectional serological survey to assess the distribution of the two diseases in the country throughout the small ruminant population.

Method. A cross-sectional study was carried out between May and December 2023 in the fourteen regions of Senegal. Animals were selected randomly from the resident sheep and goat populations. Enzyme-linked Immunosorbent Assays (ELISA) commercial ID.vet kits were used to detect RVFV and CCHFV antibodies in sera.

Results. A total of 2,127 sera from small ruminants were collected during this study. The overall seroprevalence of CCHF and RVF were 14.1 % (95% CI: 12.5 - 15.5) and 4.4% (95% CI: 3.5 - 5.3), respectively. The regions of Saint-Louis (38.4%; 95% CI: 30.4 - 46.2), Kolda (28.3%; 95% CI: 20.9 - 35.7), Tambacounda (22.2%; 95% CI: 15.8 - 28.6) and Kedougou (20.9%; 95% CI: 14.4 - 27.4) were the most affected areas. The risk factors identified during this study show that the age, species and sex of the animals were key factors in determining exposure to these two viruses. 

Conclusion. These findings suggest the active circulation of CCHFV in Senegal and provides important and consistent data that can be used to improve the surveillance strategy of RVF and CCHF in one health approach zoonoses.

Molecular Characterization of Peste Des Petits Ruminants Virus in Cameroon

Lucy M. Ndip1,2,Vivian O’Donnell3, Yaya A. Fondzenyuy1,2, Jerome K. Achah1,2, Thomas N. Masalla1,2, Keneh Nene1,2, Seraphine N. Esemu1,2, Edward Spinard4, Manuel V. Borca4, Corrie Brown5, Bertha Anyizi6, Roland N. Ndip1,2,7, Lizhe Xu3, Amy Berninger8, Douglas P. Gladue4, Bonto Faburay3,9

1 Laboratory for Emerging Infectious Diseases, University of Buea, PO Box 63, Buea, Cameroon

2Department of Microbiology and Parasitology, Faculty of Science, University of Buea, PO Box 63, Buea, Cameroon

3 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, National Bio and Agro-Defense Facility USDA, Manhattan, KS 66502, USA

4 U.S. Department of Agriculture, Agricultural Research Service, Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Orient, NY 11957 USA

5LifeStock international, Athens Georgia, USA

6Department of Veterinary Medicine, Faculty of Agriculture and Veterinary Medicine, University of Buea, Cameroon

7Department of Biotechnology and Food Technology, University of Johannesburg, Doornfontein 2094, Johannesburg, South Africa

8 Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA

9 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY 11957, USA

*Corresponding Author: Ndip.lucy@ubuea.cm 

Background: Peste des Petits Ruminants (PPR) is a distinct transboundary viral disease affecting sheep, goats and cattle, causing significant mortality and economic losses annually. The causative agent, the PPR virus, is the only member of the Morbillivirus caprinae species. It belongs to the genus Morbillivirus alongside the Rinderpest virus, which has been eradicated through vaccination. The Food and Agricultural Organization of the United Nations has launched a PPR Global Eradication Program (PPR GEP), expecting to eradicate the disease by 2030. Success of the current global eradication program will rely on surveillance efforts and knowledge of the genetic evolution of the PPR virus. 

Methods: We sequenced RNAs of seven RT-PCR positive samples from goats and sheep with Ct <27 by direct-sequencing with Oxford Nanopore Tech RNA direct sequencing kit and SISPA protocol on Illumina MiSeqPlateform. Final sequencing data of two samples, EBS03 and SBG03, were imported into CLC Genomic Workbench v24.0.1 to align to the reference genome MF737202, thereby generating the consensus sequence. The Maximum Likelihood Phylogeny tool in CLC was used to build up the phylogenic trees of the N, H and F genes of our two samples and reference PPRV isolates of different lineages.

Results: Results revealed that the current PPRV in circulation is a lineage IV variant, closely related to strains from Georgia and Ghana (H gene) and Georgia and Saudi Arabia (N gene). 

Conclusion: These findings suggest the circulation of new variants of lineage IV in Cameroon, which necessitates isolating and fully characterizing the PPR virus.

Keywords: PPRV, phylogenetics, isolates, small ruminants, Cameroon 

Outbreaks of African Swine Fever (ASF) and Seroprevalence in Cameroon

Lucy M. Ndip1,2,*,  Vivian O’Donnell3 , Yaya A. Fondzenyuy1,2, Jerome K. Achah1,2, Thomas N. Masalla1, Keneh Nene1,2, Seraphine N. Esemu1,2,, Corrie Brown4, Bertha Anyizi5, Roland N. Ndip1,2,6, Lizhe Xu7, Bonto Faburay3,7

1Laboratory for Emerging Infectious Diseases, University of Buea, PO Box 63, Buea, Cameroon

2Department of Microbiology and Parasitology, Faculty of Science, University of Buea, PO Box 63, Buea, Cameroon

3U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, National Bio and Agro-Defense Facility, USDA, Manhattan, KS 66502, USA

4LifeStock International, Atlanta, Georgia, USA

5Department of Veterinary Medicine, Faculty of Agriculture and Veterinary Medicine, University of Buea, PO Box 63, Buea, Cameroon

5Department of Biotechnology and Food Technology, Faculty of Science, University of Johannesburg, Doornfontein 2025, Johannesburg, South Africa 

7U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY 11957, USA

*Corresponding author: Ndip.lucy@ubuea.cm

Background: African swine fever (ASF) is a viral hemorrhagic disease characterized by severe lesions and high mortality rates affecting domestic pigs and wild boars globally. It is caused by the highly contagious African swine fever virus (ASFV), a member of the Asfarviridae family. In Cameroon, ASF was first reported in 1981, with subsequent outbreaks in 1982, 1994, and 2018, resulting in devastating economic consequences. Reports suggest that ASFV 

continues to circulate in Cameroon, though with isolated outbreaks. To generate current epidemiological data, an investigation was carried out in five ecological zones in Cameroon to understand the current ecological niche of ASFV.

Methods: Active surveillance involved bi-monthly sample collection involving commercial and backyard farms from March to August 2023, while all outbreaks of suspected ASF notified by the veterinary services were investigated. Blood for ELISA and nasopharyngeal swabs for PCR were collected from 295 pigs. Two sets of ELISA tests (ID VET Competition and Indirect Confirmation) were performed to detect antibodies against African Swine Fever Virus (ASFV). ASFV DNA was extracted from nasopharyngeal swab samples, and specific fragments of the ASF viral genomes (P72) were confirmed using an OIE-prescribed quantitative real-time PCR assay. 

Results: ELISA confirmed the seroprevalence of ASFV to be 7.1% (21/295), while PCR detected ASFV in 10.2% (30/295). The Guinea Savanna ecological region accounted for the majority of the positive cases, with ELISA results (19/30) and PCR results (18/30). The whole genome sequencing of representative samples collected from a domestic pig during one of the reported outbreaks revealed the circulation of genotype I. 

Conclusion: These results suggest that active surveillance of ASFV is crucial for mitigating the devastating consequences of outbreaks through containment efforts.

Seroprevalence of Crimean-Congo Haemorrhagic Fever (CCHF) and Rift Valley Fever (RVF) of Ruminants in Cameroon

Lucy M. Ndip1,2,*, Vivian O’Donnell3 , Yaya A. Fondzenyuy1,2, Jerome K. Achah1,2, Thomas N. Masalla1, Keneh Nene1,2, Seraphine N. Esemu1,2, Corrie Brown4, Bertha Anyizi5,  Roland N. Ndip1,2,6, Lizhe Xu7, Bonto Faburay3,7

1 Laboratory for Emerging Infectious Diseases, University of Buea, PO Box 63, Buea, Cameroon

2 Department of Microbiology and Parasitology, Faculty of Science, University of Buea, PO Box 63, Buea, Cameroon

3 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, National Bio and Agro-Defense Facility, USDA, Manhattan, KS 66502, USA

4 LifeStock International, Atlanta, Georgia, USA

5 Department of Veterinary Medicine, Faculty of Agriculture and Veterinary Medicine, University of Buea, PO Box 63, Buea, Cameroon

6 Department of Biotechnology and Food Technology, Faculty of Science, University of Johannesburg, Doornfontein 2025, Johannesburg, South Africa 

7 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, Plum Island Animal Disease Center, Greenport, NY, USA

*Corresponding author: Ndip.lucy@ubuea.cm

Background: Crimean-Congo Haemorrhagic Fever (CCHF) and Rift Valley Fever (RVF) are zoonotic viral diseases. Though handling of animals is strongly associated with both diseases in humans, the epidemiology of these diseases in Cameroon remains largely underreported. This study aims to determine the seroprevalence of these diseases in animals from different locations in Cameroon. 

Method:Plasma samples were collected from 1,516 animals comprising 631 cattle, 477 goats and 408 sheep to determine the seroprevalence of IgG and IgM antibodies to RVFV and CCHFV. All samples were shipped to the Laboratory for Emerging Infectious Diseases, University of Buea, and analysed using competitive or capture ELISA (c-ELISA) and double antigen ELISA (DA-ELISA) (IDvet, Grabels, France) for detection of anti-RVFV antibodies and anti-CCHFV antibodies, respectively. A questionnaire was used to collect data on the animals and farms to analyse for risk factors.

Results: The seroprevalence of CCHF virus was 29.2% (443/1,516) while RVFV seroprevalence was demonstrated in 26 (1.7%) animals. For CCHF virus, there was a significantly higher seroprevalence in cattle, while age, farming system and farm size were risk factors associated with CCHFV. Conversely, the seroprevalence of RVF was higher in small ruminants (sheep and goats), respectively (16; 4.0%), and (8; 1.7%). Only visit by veterinarian and/or livestock technician was significantly associated with RVFV seroprevalence. In regional stratification, the Far North region demonstrated highest RVFV seroprevalence in livestock, while CCHFV seroprevalence was highest in the Littoral region. The seroprevalence by region was statistically different (X2= 82.42; p = 0.000) for CCHFV but not for RVFV. In all regions, except the Far North, pastoral animals had a higher seroprevalence of CCHF than sedentary. 

Conclusion:CCHF and RVF viruses are circulating in domesticated animal populations in Cameroon, and active surveillance of animal and human populations is important to detect and mitigate the effects of outbreaks through early detection. 

Peste des Petits Ruminants Virus (PPRV) in The Gambia: Seroprevalence and Genetic Sequencing 

Momodou Jeng1*, Kebba Daffeh1, Joseph A. E. Faye1, Olawale Olaniyan1, Corrie Brown2, Jeffrey M.B. Musser2, Jerusha Matthews3, Lizhe Xu3, Bonto Faburay3

1West Africa Livestock Innovation Centre, PMB 14, Banjul, The Gambia

2LifeStock International, Athens, Georgia, USA

3U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Foreign Animal Disease Diagnostic Laboratory, National Bio and Agro-Defense Facility, Manhattan, KS, USA 

*Corresponding Author - mojeng2000@hotmail.com

Background. Peste de petit ruminants (PPR) is an endemic disease in The Gambia that can result in decreased productivity and high mortality within infected small ruminant flocks. Currently in The Gambia, seroprevalence and circulating morbillivirus lineages of PPR are unknown. We investigated PPR seroprevalence, along with agreement between West Africa Livestock Innovation Centre (WALIC) and Foreign Animal Disease Diagnostic Laboratory (FADDL), and the circulating morbillivirus lineages of PPR in The Gambia. 

Methods. During April and May 2023, serum samples were taken from of 400 healthy sheep and 419 healthy goats, while oral-nasal swabs were taken from 67 goats and 9 sheep with clinical signs consistent with PPR. Sampling covered all 6 administrative divisions of The Gambia. Serology on paired samples was determined by WALIC in The Gambia and by FADDL in the USA. Thirteen swab samples (11 goat and 2 sheep) were sequenced using a nanopore next-generation sequencer and a Direct RNA Sequencing protocol at the Foreign Animal Disease Diagnostic Laboratory (FADDL). Maximum Likelihood phylogeny (MLP) tree was built based on MSA performed on the full genome sequence of samples against 19 PPRV full-length sequences with known lineage isolates from GenBank.

Results. Serological results at WALIC were 540 seropositive and 279 seronegative samples, while those at FADDL were 531 seropositive and 288 seronegative samples. Cohen’s Kappa was 0.668 indicating a substantial agreement between the two laboratories. Agreement between the laboratories did not occur in 15.0% of the samples – 66 samples were seropositive by WALIC but seronegative by FADDL and 57 samples were seronegative by WALIC but seropositive by FADDL. Ten (9 goats and 1 sheep) of 13 sequenced samples generated reads aligned to PPRV. Bioinformatic pipeline found PPRV Nigeria_NGYO2013-2162 (KR828813.1) as the closest reference for the 9 goat samples, while the 1 sheep sample was closer to the PPRV Senegal SnDk11I13 (KM212177.1). Maximum likelihood phylogeny trees, based upon one sample from each of the isolate groups, showed the group of 10 samples closely related to lineage IV and 1 sample closely related to lineage II. 

Conclusion. Seroprevalence of PPR in The Gambia was estimated to be 66%, with substantial agreement between the results from WALIC and FADDL, though not 100% agreement. Sequencing identified two novel Gambia PPRV isolates: one related to Nigeria isolate (KR828813.1) and one to Senegal isolate (KM212177.1). Downstream phylogenetic analysis indicates that lineage IV predominated. The Gambia PPRV lineage IV may be due to introduction into the country due to cross-border trade and movement of livestock. This study provides a first step in understanding and eventual eradication of PPR in The Gambia. More research on Gambia PPRV lineage IV and lineage II are needed.