Parasites burden in peri-urban free-roaming pigs in Gert Sibande District Municipality, Mpumalanga Province, South Africa

BACKGROUND

Parasite infections, unlike regulated animal diseases, do not often receive attention. In fact, parasites are major sources of financial losses in pig enterprises, particularly in subsistence and small-scale pig production systems.

OBJECTIVE

To identify and quantify the prevalence of ecto- and endo-parasites among peri-urban free-roaming pigs (FRP) in Gert Sibande District Municipality (GSDM), Mpumalanga.

METHODS

Pig owners were identified using the snowball sampling method since no sampling frame for FRP farmers exists. Stratified sampling was used to select pigs for sampling for ecto- and endo-parasites. A form was used to record the observations. Pairwise correlation analysis was performed using Stata 15.0. The SPSS V28.0 statistical package was used to perform the chi-square test (X2) to assess the distribution of parasites in different age groups. The prevalence of parasites was assessed in different age groups of pigs using multi-response crosstabs. Multivariate analysis of variance (MANOVA) was used to estimate the marginal mean of parasites according to municipality. Statistical significance was assessed at α ≤ 0.05.

RESULTS

Over 90% (91.2%) of the pigs examined were infested with at least one parasite, including Haematopinus suis, Sarcoptes scabiei, Ascaris suum, Fasciola hepatica, Trichuris suis, Strongylids, Coccidia spp, Moniezia expansa, and Siphonaptera spp. The correlation between Ascaris suum and body condition was weak but statistically significant (r = 0.24; p < 0.05).

CONCLUSION

Policy makers, animal researchers and veterinary services must focus on developing policies, risk communication and community engagement materials, which target pig farmers in peri-urban areas such as Gert Sibande District Municipality, Mpumalanga Province.

High-Risk Regions of African Swine Fever Infection in Mozambique

African swine fever (ASF) is a transboundary infectious disease that can infect wild and domestic swine and requires enhanced surveillance between countries. In Mozambique, ASF has been reported across the country, spreading between provinces, mainly through the movement of pigs and their by-products. Subsequently, pigs from bordering countries were at risk of exposure. This study evaluated the spatiotemporal distribution and temporal trends of ASF in swine in Mozambique between 2000 and 2020. During this period, 28,624 cases of ASF were reported across three regions of the country. In total, the northern, central, and southern regions presented 64.9, 17.8, and 17.3% of the total cases, respectively. When analyzing the incidence risk (IR) of ASF per 100,000 pigs, the Cabo Delgado province had the highest IR (17,301.1), followed by the Maputo province (8868.6). In the space-time analysis, three clusters were formed in each region: (i) Cluster A involved the provinces of Cabo Delgado and Nampula (north), (ii) Cluster B involved the province of Maputo and the city of Maputo (south), and (iii) Cluster C consisted of the provinces of Manica and Sofala (central) in 2006. However, when analyzing the temporal trend in the provinces, most were found to be decreasing, except for Sofala, Inhambane, and Maputo, which had a stationary trend. To the best of our knowledge, this is the first study to evaluate the spatial distribution of ASF in Mozambique. These findings will contribute to increasing official ASF control programs by identifying high-risk areas and raising awareness of the importance of controlling the borders between provinces and countries to prevent their spread to other regions of the world.

Innovative Research Offers New Hope for Managing African Swine Fever Better in Resource-Limited Smallholder Farming Settings: A Timely Update

African swine fever (ASF) in domestic pigs has, since its discovery in Africa more than a century ago, been associated with subsistence pig keeping with low levels of biosecurity. Likewise, smallholder and backyard pig farming in resource-limited settings have been notably affected during the ongoing epidemic in Eastern Europe, Asia, the Pacific, and Caribbean regions. Many challenges to managing ASF in such settings have been identified in the ongoing as well as previous epidemics. Consistent implementation of biosecurity at all nodes in the value chain remains most important for controlling and preventing ASF. Recent research from Asia, Africa, and Europe has provided science-based information that can be of value in overcoming some of the hurdles faced for implementing biosecurity in resource-limited contexts. In this narrative review we examine a selection of these studies elucidating innovative solutions such as shorter boiling times for inactivating ASF virus in swill, participatory planning of interventions for risk mitigation for ASF, better understanding of smallholder pig-keeper perceptions and constraints, modified culling, and safe alternatives for disposal of carcasses of pigs that have died of ASF. The aim of the review is to increase acceptance and implementation of science-based approaches that increase the feasibility of managing, and the possibility to prevent, ASF in resource-limited settings. This could contribute to protecting hundreds of thousands of livelihoods that depend upon pigs and enable small-scale pig production to reach its full potential for poverty alleviation and food security.

Epidemiology of Porcine Cysticercosis in Eastern and Southern Africa: Systematic Review and Meta-Analysis

Taenia solium cysticercosis is the most common cause of acquired epilepsy in pig-raising and pork-consuming parts of Africa, Latin America, and Asia. This review aimed to systematically compile and synthesize data on the epidemiology of porcine cysticercosis in the Eastern and Southern Africa (ESA) region. Comprehensive searching strategies were employed to retrieve the studies published or reported between January 1,1997 and March 1, 2021, from Pub Med, Hinari, and Google Scholar databases and search platforms. The identified studies that met the inclusion criteria were then appraised for methodological quality. Finally, 44 studies obtained from nine countries were selected and included in this review. Relevant data were extracted using standardized templates for qualitative synthesis and meta-analysis. The overall pooled prevalence estimate of porcine cysticercosis in the ESA region was 17% (95% CI: 14-20%). The prevalence level between and within countries showed high variability. The pooled estimate showed high heterogeneity among the reports (the inverse variance index value (I2) of 98.99%, p < 0.05). The meta-analysis sub-grouped by the type of diagnostic test showed the pooled prevalence estimate of 27% (95% CI: 9-50) by carcass dissection; 23% (95% CI: 14-33) by Antibody-based immunodiagnostic techniques; 23% (95% CI: 18-29) by antigen detecting (Ag)-ELISA, 12% (95% CI: 7-18) by meat inspection, and 9% (95% CI: 7-11) by lingual examination. The meta-analysis sub-grouped by region showed a relatively higher pooled prevalence estimate for the Southern region 22% (95% CI: 15-30) compared to 13% (95% CI: 11-15) in the Eastern region. The highest country-based pooled prevalence was obtained from South Africa (33%, 95% CI: 20-48) and Zambia (22%, 95% CI: 16-29), whereas the lowest pooled prevalence was identified in Madagascar (5%, 95% CI: 4-5) and Rwanda (7%, 95% CI: 6-8). The lack of latrine, traditional pig husbandry practices, unprotected water sources, and increase in age were identified as significant risk factors for the occurrence of porcine cysticercosis in the pooled studies. The findings of this review will provide context-specific input to prioritize the possible intervention programs for T. solium control in the ESA region. More sensitive and specific test-based prevalence estimates, detailed risk factor investigations, and financial losses analysis are needed to establish feasible control strategies.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021238931.

Prevalence and genome characterization of porcine rotavirus A in southern Mozambique

Rotavirus A (RVA) is an important pathogen causing gastroenteritis in many species, including humans and pigs. The objective of this study was to determine the prevalence of RVA in pigs from smallholdings and commercial farms in southern Mozambique and characterize the complete genomes of selected strains. RVA was detected at a rate of 11.8% (n = 288), of which 7.6% was detected at commercial farms and 4.2% at smallholdings. The whole genomes of eight rotavirus strains were determined using an Illumina MiSeq platform. Seven displayed a G9P[13] and one a G4P[6] genotype combination, all with a typical porcine backbone (I1/5-R1-C1-M1-A1/8-N1-T1/7-E1-H1). Phylogenetic analysis indicated that the seven G9P[13] strains were in fact one strain that circulated on a commercial pig farm. The genome segments of this strain clustered with diverse segments of human and porcine RVA strains from various Asian countries. Analysis of the G4P[6] strain revealed four distinct genome segments (VP2, VP4, VP6 and VP7) and five genome segments closely related to South African porcine rotavirus strains (NSP1, NSP3, NSP4, NSP5 and VP1). These results suggest that both the G4P[6] and the G9P[13] strains possibly emerged through multiple reassortment events. The presence of these strains on the commercial farms and smallholdings calls for a more in-depth surveillance of rotavirus in Mozambique.

Genetic characterization of African swine fever virus isolates from soft ticks at the wildlife/domestic interface in Mozambique and identification of a novel genotype

African swine fever virus (ASFV) is one of the most threatening infectious diseases of pigs. There are not sufficient data to indicate the importance of the sylvatic cycle in the spread and maintenance of the disease locally and potentially, globally. To assess the capacity to maintain ASF in the environment, we investigated the presence of soft tickreservoirs of ASFV in Gorongosa National Park (GNP) and its surrounding villages. A total of 1,658 soft ticks were recovered from warthog burrows and pig pens at the wildlife/livestock interface of the GNP and viral DNA was confirmed by nested PCR in 19% of Ornithodoros porcinus porcinus and 15% of O. p. domesticus. However, isolation of ASFV was only achieved in approximately 50% of the PCR-positive samples with nineteen haemadsorbing virus isolates recovered. These were genotyped using a combination of partial sequencing of the B646L gene (p72) and analysis of the central variable region (CVR) of the B602L gene. Eleven isolates were classified as belonging to genotype II and homologous to contemporary isolates from southern Africa, the Indian Ocean and eastern Europe. Three isolates grouped within genotype V and were similar to previous isolates from Mozambique and Malawi. The remaining five isolates constituted a new, previously unidentified genotype, designated genotype XXIV. This work confirms for the first time that the virus currently circulating in eastern Europe is likely to have a wildlife origin, and that the large diversity of ASFV maintained in wildlife areas can act as a permanent sources of different strains for the domestic pig value chain in Mozambique and beyond its boundaries. Their genetic similarity to ASFV strains currently spreading across Europe justifies the need to continue studying the sylvatic cycle in this African country and other parts of southern Africa in order to identify potential hot spots of ASF emergence and target surveillance and control efforts.

Piloting the effectiveness of pig health education in combination with oxfendazole treatment on prevention and/or control of porcine cysticercosis, gastrointestinal parasites, African swine fever and ectoparasites in Angónia District, Mozambique

A community-based intervention combining health education (HE) and treatment of pigs for control of porcine cysticercosis (PC), gastrointestinal (GI) helminths, African swine fever (ASF) and external parasites was tested involving six villages of resource-poor smallholder pig farmers. Farmers and pigs of six rural villages were randomly allocated into group 1 (HE), which served as controls, and group 2 (HE + OFZ) pigs received a single oral dose of 30 mg/kg OFZ. Farmers were trained in pig health, housing and feeding. The proportion of farmers with confined pigs, the adoption rate of the introduced pig pen, the sero-prevalence of PC and ASF, the prevalence and intensity of GI nematodes and the prevalence of ectoparasites were measured at 9, 15 and 24 months after initiation and compared to a baseline survey to seek the effectiveness of the interventions. There was no clear effect of the intervention on the sero-prevalence of PC, but analysis of the rate of change in prevalence between the two groups showed significant effect with the rate of change to lower prevalence in the HE + OFZ group compared to the HE group. Although HE managed to improve the farmer's knowledge in the control and prevention of ASF and ectoparasites, there was no significant reduction in the sero-prevalence of ASF and the prevalence of ectoparasites throughout the two-year period. The reported ineffectiveness of the intervention in this study suggested that more research is needed to develop more effective methods for controlling PC, ASF and pig parasites.

Prevalence and risk factors of endo- and ectoparasitic infections in smallholder pigs in Angónia district, Mozambique

A cross-sectional study was carried out to determine the prevalence and associated risk factors of parasitic infections in pigs kept under smallholder farming system in Angónia district, Tete Province, Mozambique. A total of 262 pigs from 133 households of six villages were randomly selected. From each pig blood, faecal samples, full body searches, and skin scrapings were conducted to determine the prevalence of Taenia solium (using Ag-ELISA), gastrointestinal (GI) parasites, and ectoparasites respectively. A questionnaire survey was administered to smallholder pig farmers to assess their knowledge and perceptions of health and pig management and an observational study was conducted to determine their pig management practices. The overall prevalence of porcine cysticercosis by Ag-ELISA was 12.6%, GI nematodes 21.4%, Eimeria spp. 8.0% and ectoparasites 37.8%. Four helminths species namely, Metastrongylus spp., Hyostrongylus spp., Oesophagostomum spp., Trichostrongylus spp., were identified from by copro culture, and through faecal egg count, Ascaris suum and Trichuris suis were identified. Haematopinus suis, Rhipicephalus spp. and Echidnophaga gallinacea were found with a prevalence of 32.4%, 7.6%, and 6.9%, respectively. The only significant risk factor identified to be related to the parasite prevalence was pig origin (village), for both gastrointestinal parasites (OR=10.81[0.81-57.27]) and ectoparasites (OR=7.06[1.42-35.03]). This study provided evidence that parasitic infections in pigs constitute a major burden for smallholder pig farmers in Angónia district, and that porcine cysticercosis is a public health threat in the area and immediate attention is needed for control and prevention of the parasite.

Taenia solium taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa

Background

This study aimed to map the distribution of Taenia solium taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa. These two major neglected tropical diseases are presumed to be widely distributed in Africa, but currently the level of co-distribution is unclear.

Methods

A literature search on T. solium taeniosis/cysticercosis was performed to compile all known studies on the presence of T. solium and apparent prevalence of taeniosis and porcine cysticercosis in Africa. Studies were geo-referenced using an online gazetteer. A Bayesian framework was used to combine the epidemiological data on the apparent prevalence with external information on test characteristics to estimate informed district-level prevalence of taeniosis and porcine cysticercosis. Districts with T. solium taeniosis/cysticercosis presence were cross-referenced with the Global Neglected Tropical Diseases Database for schistosomiasis presence.

Results

The search strategies identified 141 reports of T. solium in Africa from 1985 to 2014 from a total of 476 districts in 29 countries, 20 with porcine cysticercosis, 22 with human cysticercosis, and 16 with taeniosis, in addition to 2 countries identified from OIE reports. All 31 countries were considered, on national scale, to have co-distribution with schistosomiasis. Presence of both parasites was confirmed in 124 districts in 17 countries. The informed prevalence of taeniosis and porcine cysticercosis were estimated for 14 and 41 districts in 10 and 13 countries, respectively.

Conclusions

With the paucity of data, T. solium infection is grossly under-reported and expected to be more widespread than this study suggests. In areas where co-distribution occurs there is a need for increased emphasis on evaluation of integrated intervention approaches for these two helminth infections and allocation of resources for evaluating the extent of adverse effects caused by mass drug administration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0938-7) contains supplementary material, which is available to authorized users.

Investigation into the Epidemiology of African Swine Fever Virus at the Wildlife - Domestic Interface of the Gorongosa National Park, Central Mozambique

An epidemiological study of African swine fever (ASF) was conducted between March 2006 and September 2007 in a rural area adjacent to the Gorongosa National park (GNP) located in the Central Mozambique. Domestic pigs and warthogs were sampled to determine the prevalence of antibodies against ASF virus and the salivary antigens of Ornithodoros spp. ticks, while ticks collected from pig pens were tested for the presence of ASFV. In addition, 310 framers were interviewed to gain a better understanding of the pig value chain and potential practices that could impact on the spread of the virus. The sero-prevalence to ASFV was 12.6% on farms and 9.1% in pigs, while it reached 75% in warthogs. Approximately 33% of pigs and 78% of warthogs showed antibodies against salivary antigens of ticks. The differences in sero-prevalence between farms close to the GNP, where there is greater chance for the sylvatic cycle to cause outbreaks, and farms located in the rest of the district, where pig to pig transmission is more likely to occur, were marginally significant. Ornithodoros spp. ticks were found in only 2 of 20 pig pens outside the GNP, and both pens had ticks testing positive for ASFV DNA. Interviews carried out among farmers indicated that biosecurity measures were mostly absent. Herd sizes were small with pigs kept in a free-ranging husbandry system (65%). Only 1.6% of farmers slaughtered on their premises, but 51% acknowledged allowing visitors into their farms to purchase pigs. ASF outbreaks seemed to have a severe economic impact with nearly 36% of farmers ceasing pig farming for at least 1 year after a suspected ASF outbreak. This study provides the first evidence of the existence of a sylvatic cycle in Mozambique and confirms the presence of a permanent source of virus for the domestic pig value chain.

African swine fever virus eradication in Africa

African swine fever was reported in domestic pigs in 26 African countries during the period 2009-2011. The virus exists in an ancient sylvatic cycle between warthogs (Phacochoerus africanus) and argasid ticks of the Ornithodoros moubata complex in many of the countries reporting outbreaks and in two further countries in the region. Eradication of the virus from the countries in eastern and southern Africa where the classic sylvatic cycle occurs is clearly not an option. However, the virus has become endemic in domestic pigs in 20 countries and the great majority of outbreaks in recent decades, even in some countries where the sylvatic cycle occurs, have been associated with movement of infected pigs and pig meat. Pig production and marketing and ASF control in Africa have been examined in order to identify risk factors for the maintenance and spread of ASF. These include large pig populations, traditional free-range husbandry systems, lack of biosecurity in semi-intensive and intensive husbandry systems, lack of organisation in both pig production and pig marketing that results in lack of incentives for investment in pig farming, and ineffective management of ASF. Most of these factors are linked to poverty, yet pigs are recognised as a livestock species that can be used to improve livelihoods and contribute significantly to food security. The changes needed and how they might be implemented in order to reduce the risk of ASF to pig producers in Africa and to the rest of the world are explored.