Endemic and emerging arboviral diseases of livestock in Nigeria: a review

Seroprevalence and Co-Circulation of Rift Valley Fever Virus and West Nile Fever Virus in Livestock Population of Afar Region, Northeast Ethiopia

The distribution, epidemiology, and socioeconomic impact of Rift Valley fever (RVF) and West Nile (WN) viruses are poorly known in areas of sub-Saharan countries like Ethiopian pastoral region. The human and livestock density in the area has increased greatly in recent years, but little work has been done on arboviral diseases and their potential impact on human and livestock health. The aim of this study was to detect the circulation of zoonotic arboviruses such as Rift Valley fever virus and West Nile viruses in the livestock population and to estimate seroprevalence in Afar pastoral area northeast Ethiopia. Cross-sectional serological survey was carried out in 736 serum samples from which cattle (224), camel (155), goats (121), sheep (144), and donkeys (92) were tested for the presence of anti-RVFV and anti-WNV IgG using a competitive enzyme-linked immunosorbent assay (c-ELISA) in two purposively selected districts of the Afar region. The present study revealed a 9.1% (95% CI = 8.86-9.29) seroprevalence of co-circulation of RVF and WNV. High 32/155 (20.7%) seroprevalence of co-circulation was seen in camels, followed by goat 14/121 (11.6%), cattle 16/224 (7.14%), and sheep 5/144 (3.5%), respectively, and higher 41/421 (9.7%) seroprevalence of co-circulation was observed in Amibara district than Haruka district. Camels were seven times (OR: 7.016, 95% CI = 2.639-18.653) more likely to be seropositive for the co-circulation than sheep (p ≤ 0.001). Livestock herds found in Amibara district were 1.2 times (OR: 1.165, 95% CI = 0.680-1.996) more likely to be seropositive for RVFV infection than those in Haruka areas. Given the co-occurrence of RVFV and WNV circulations, along with often suboptimal human and animal health surveillance in many similar areas' attention should be given. Investigation of the potential socioeconomic and health impacts of zoonotic arbovirus infections in such areas is crucial. Since both RVFV and WNFV are transmitted through a mosquito vector, avoiding mosquito bites is the primary method of prevention.

Modeling the spatial distribution of Culicoides species (Diptera: Ceratopogonidae) as vectors of animal diseases in Ethiopia

Culicoides biting midges (Diptera: Ceratopogonidae) are the major vectors of bluetongue, Schmallenberg, and African horse sickness viruses. This study was conducted to survey Culicoides species in different parts of Ethiopia and to develop habitat suitability for the major Culicoides species in Ethiopia. Culicoides traps were set in different parts of the country from December 2018 to April 2021 using UV light Onderstepoort traps and the collected Culicoides were sorted to species level. To develop the species distribution model for the two predominant Culicoides species, namely Culicoides imicola and C. kingi, an ensemble modeling technique was used with the Biomod2 package of R software. KAPPA True skill statistics (TSS) and ROC curve were used to evaluate the accuracy of species distribution models. In the ensemble modeling, models which score TSS values greater than 0.8 were considered. Negative binomialregression models were used to evaluate the relationship between C. imicola and C. kingi catch and various environmental and climatic factors. During the study period, a total of 9148 Culicoides were collected from 66 trapping sites. Of the total 9148, 8576 of them belongs to seven species and the remaining 572 Culicoides were unidentified. The predominant species was C. imicola (52.8%), followed by C. kingi (23.6%). The abundance of these two species was highly influenced by the agro-ecological zone of the capture sites and the proximity of the capture sites to livestock farms. Climatic variables such as mean annual minimum and maximum temperature and mean annual rainfall were found to influence the catch of C. imicola at the different study sites. The ensemble model performed very well for both species with KAPPA (0.9), TSS (0.98), and ROC (0.999) for C. imicola and KAPPA (0.889), TSS (0.999), and ROC (0.999) for C. kingi. Culicoides imicola has a larger suitability range compared to C. kingi. The Great Rift Valley in Ethiopia, the southern and eastern parts of the country, and the areas along the Blue Nile and Lake Tana basins in northern Ethiopia were particularly suitable for C. imicola. High suitability for C. kingi was found in central Ethiopia and the Southern Nations, Nationalities and Peoples Region (SNNPR). The habitat suitability model developed here could help researchers better understand where the above vector-borne diseases are likely to occur and target surveillance to high-risk areas.

Relative abundance and molecular identification of Culex pipiens complex (Diptera: Culicidae), in Kura Local Government Area, North-western Nigeria

Culex species are the most widespread mosquito species across the world and are known to be highly opportunistic, feeding on humans and livestock. They are known to acquire the potential to transmit zoonotic diseases, including Rift Valley Fever (RVF). However, despite their public health significance, they remain understudied in North-western Nigeria, compared to Anophelines. This study was therefore aimed at determining the relative abundance and Multiplex polymerase chain reaction (Multiplex PCR) identification of members of the Culex pipiens complex, in Kura Local Government Area (LGA), North-western, Nigeria. Adult mosquitoes were collected using Center for Disease Control (CDC) miniature light traps from August to October 2019. Mosquitoes were identified using morphological identification keys. Members of the Culex pipiens complex were further identified using Multiplex PCR to assess the presence of sibling species. A total of 413 mosquitoes, belonging to 3 genera, Culex, Anopheles and Aedes were collected. Of this figure, 120 Culex spp. females were collected. Homes with livestock had the highest occurrence of mosquitoes, 123 (61.19%) compared to those without livestock, 78 (38.81%). There was no statistical difference among the two (2) categories of homes (P ≥ 0.005). Culicoides spp. were the most common with 130 collected (65.38%). Again, homes with livestock had the highest occurrence, 85 whilst homes without livestock had 45 of the other flies caught. Multiplex- PCR revealed no expected bands for Cx. quinquefasciatus and Cx. pipiens from the DNA obtained from field collected mosquitoes as confirmed by using genomic DNA of an insectary Culex quinquefasciatus as control. Cx. spp. is presently regarded as a biting nuisance having no significant epidemiological importance. Efforts at its control should be intensified before it is too late. This study provides useful information on the occurrence and multiplex PCR of Culex spp in Kura Local Government Area, North-western Nigeria. These results have implications for the control of Culex spp. mosquito populations and the spread of human, livestock and avian diseases.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

The first detection of anti-West Nile virus antibody in domestic ruminants in Egypt

West Nile virus (WNV) is a mosquito-borne disease, usually present as a symptomatic disease but can cause various clinical signs ranged from mild fever to severe encephalitis and death in various animals and humans. In Egypt, the epidemiological data about WNV infection in different animal species particularly in domestic ruminants are scarce. The present study aimed to investigate the seroprevalence of WNV in cattle, buffalo, camel, sheep, and goats at some Governorates northern Egypt. In total, 360 serum samples (100 cattle, 50 buffalo, 50 camels, 85 sheep, and 75 goats) were examined using ELISA. The results revealed that the seroprevalence of WNV among ruminants was highly significant (P = 0.03) at Kafr El Sheikh Governorate (17.6%) in comparison with other the Governorates. Besides, the seroprevalence of WNV antibodies significantly differed between the examined species (P = 0.0001); it was 22%, 0%, 40%, 3.5%, and 5.3% in cattle, buffalo, camel, sheep, and goats, respectively. This is the first study to confirm that domestic ruminants act as a reservoir in the epidemiology of WNV infection and represent a risk for human and equine infections in Egypt.

Prevalence and risk factors of some arthropod-transmitted diseases in cattle and sheep in Jordan

Aims:

The objectives of this study were to determine the prevalence and associated risk factors of bluetongue virus (BTV) in sheep and bovine ephemeral fever virus (BEFV) in dairy cattle in Jordan.

Materials and Methods:

A simple randomized study was designed to collect 600 serum samples from sheep and 300 serum samples from dairy cattle located in the Northwestern parts of Jordan. In addition, data regarding farm management were collected using a pre-tested questionnaire through personal interview to determine potential risk factors. The seroprevalences of BEF and BTVs were determined using serum neutralization test and BTV group-specific competitive enzyme-linked immunosorbent assay, respectively.

Results:

The overall seroprevalence of neutralizing antibodies against BEFV in dairy cattle was 45.37%. The overall seroprevalence of BTV group-specific antibodies in sheep was 47.8% (54% true seroprevalence). Logistic regression analysis identified geographic location (Irbid) (odds ratio [OR]=1.0; confidence interval [CI]=0.5-2.1), no use of disinfectants on the farm (OR=1.0; CI=0.05-0.1), and lack of veterinary services (OR=10; CI=3.5-13.2) as risk factors associated with high seropositivity against BTV in sheep. Geographic location (Jarash) (OR=3; CI=1.0-5.5), age of the animal (1-2 years of age (OR=1; CI=0.3-1.9), and lack of veterinary services (OR=9; CI=4-11) were identified as risk factors associated with high seroprevalence against BEFV in dairy cattle.

Conclusion:

Results of this study indicate that BEFV in dairy cattle and BTV in sheep are endemic in Northwestern regions of Jordan. Implementation of appropriate control measures is, therefore, required to reduce the adverse effects of these diseases on animal health and productivity.