Investigation into eradication of African swine fever in domestic pigs from a previous outbreak (2016/17) area of South Africa.

A serological survey was conducted to evaluate the eradication of African swine fever (ASF) infection eighteen months after clinical surveillance and selective culling had been completed during domestic cycle outbreaks in parts of South Africa in 2016/17. Three hundred and twenty-two serum samples from 85 pig keepers were collected in the study area and tested for the presence of antibodies against the ASF virus (ASFV). None of the samples contained detectable levels of antibodies against ASFV. These results together with the findings from clinical surveillance following culling activities suggest that the disease had been eradicated from the domestic pig population in this area following the outbreaks. Questionnaire responses from the pig keepers in this area highlighted the need to implement basic biosecurity measures in smallholder pig keepers to prevent outbreaks of ASF in South Africa.

Investigation of African swine fever outbreaks in pigs outside the controlled areas of South Africa, 2012-2017.

South Africa historically experienced sporadic African swine fever (ASF) outbreaks in domestic pigs in the northern parts of the country. This was subsequently indicated to be because of spillover from the sylvatic cycle of ASF between warthog and tampans (soft ticks) in the area. South Africa declared this area an ASF-controlled area in 1935, and the area is still controlled in terms of the Animal Diseases Act, 1984 (Act 35 of 1984). Two main epidemics of ASF in domestic pigs were identified outside of the South African ASF-controlled area. The first occurred in 2012 with outbreaks in Gauteng and Mpumalanga provinces, and the second occurred in 2016-2017 with outbreaks in the North West, Free State and Northern Cape provinces. These were the first ASF epidemics in South Africa associated with transmission of the disease via a domestic cycle. This study found that the spread of ASF in these epidemics was mainly via auctions, swill feeding and scavenging. These three aspects need to be addressed in terms of awareness and education on the disease including implementation of biosecurity measures in order to prevent future ASF outbreaks in South Africa. Specific biosecurity measures should be implemented in the semi-commercial sector to prevent ASF-infected pigs and pig products from being moved to naïve pigs and therefore spreading the disease.

Reporte de resultados negativos a Trichinella spp. por digestión artificial en cerdos domésticos del valle inferior del río Negro, Patagonia Argentina / Report of negative results to Trichinella spp. by artificial digestion in domestic pigs of the lower valley of the Negro River, Argentine Patagonia

Resumen Actualmente, el género Trichinella está constituido por 10 especies y 3 genotipos. La transmisión ocurre únicamente por ingestión de tejido muscular infectado. Entre los potenciales hospedadores se conforma un ciclo doméstico y un ciclo silvestre con posible retroalimentación constante entre ambos. Desde el año 2017 el funcionamiento del Matadero Social de San Javier, en el valle inferior del río Negro, permite a productores acceder a una faena segura que además brinde garantías al consumidor. El objetivo del presente trabajo fue evaluar la presencia de larvas L1 de Trichinella spp. en porcinos domésticos procedentes de criaderos de pequeña y mediana escala. Se analizaron por el método de digestión artificial 10 gramos de diafragma de cada porcino doméstico, conformando pooles de hasta 10 animales. En total 942 porcinos domésticos resultaron negativos a la presencia de larvas L1 de Trichinella spp. No obstante debe tenerse presente que sistemas de producción con las características de los que provienen los animales analizados, estarían potencialmente expuestos a la retroalimentación de Trichinella spp. desde la fauna silvestre. En este marco, resulta necesario garantizar el control veterinario en la faena de porcinos y presas de caza y sostener acciones de vigilancia, actualización y promoción en relación a la prevención de la triquinelosis.

Abstract Currently the Trichinella genus consists of 10 species and 3 genotypes. Transmission occurs only through ingestion of infected muscle tissue. Between the potential hosts there is a domestic cycle and a wild cycle with possible constant feedback between both. Since 2017, the operation of the San Javier Social Slaughterhouse, in the lower valley of the Río Negro, allows producers to access a safe operation that also provides guarantees to the consumer. The aim of the present study was to evaluate the presence of L1 larvae larvae of Trichinella spp. in domestic pigs from small and medium-scale farms. 10 grams of diaphragm from each domestic pig were analyzed by the artificial digestion method, forming pools of up to 10 animals. In total 942 domestic pigs were negative for the presence of L1 larvae of Trichinella spp. However, it should be borne in mind that production systems with the characteristics from which the analyzed animals come, would potentially be exposed to the feedback of Trichinella spp. from wildlife. Then, it is necessary to guarantee veterinary control in the slaughter of pigs and game prey and to support surveillance, updating and promotion actions in relation to the prevention of trichinellosis.

Trichinella spp. in wild mesocarnivores in an endemic setting.

Human trichinellosis and Trichinella infection in pigs are both still endemic in the Balkans, including Serbia. Because of the flow between the sylvatic and the domestic cycle of Trichinella spp., monitoring wildlife has been recommended for the risk assessment of Trichinella spp. infection in swine. We have previously shown the presence of Trichinella infection in wild carnivores including the wolf and the golden jackal, and here we report on Trichinella infection in several other mesocarnivore species. From a total of 469 animals collected between 1994 and 2013, Trichinella larvae were detected in 29 (6.2%, 95% CI = 4.0-8.4) animals, including 14 red foxes (4.7%), 7 wild cats (35%), 5 beech martens (4.8%), 2 pine martens (16.7%), and 1 European badger (6.25%). No Trichinella larvae were detected in the examined specimens of European polecats, steppe polecats and European otters. Species identification of the Trichinella larvae performed for 18 positive samples revealed T. spiralis in 77.8% and T. britovi in 22.2% of the isolates. Both species were detected in red foxes and wild cats. The predominance of T. spiralis in wildlife in Serbia indicates the (past or present) spillover of this pathogen from domestic to wild animals.

Trichinella spiralis prevalence among wildlife of a boreal region rapidly reduced in the absence of spillover from the domestic cycle.

Carnivore and omnivore animals are the main reservoir hosts of nematodes of the genus Trichinella. Out of the twelve taxa identified so far in the world, four, namely Trichinella spiralis, Trichinella nativa, Trichinella britovi and Trichinella pseudospiralis, are circulating in Europe. All these four species were detected in Finnish wild animals and T. spiralis also in domestic pigs and synanthropic rats of Finland up to 2004, when the last T. spiralis infection was documented in a domestic pig. In the periods 1993-1997 and 1999-2005, T. spiralis was detected in 13.6% (6/44) and in 14.5% (46/317) of infected wild animals, respectively. The aims of the present study were to investigate the prevalence of Trichinella spp., especially T. spiralis in wild carnivores of Finland, 7-9 years after the eradication of Trichinella infection from Finnish domestic pigs, and to evaluate the impact of the disappearance of domestic cycle of T. spiralis on the sylvatic Trichinella cycle(s). Trichinella spp. larvae were detected in 34.7% (1081/3112) wild animals and 835 (77.2%) Trichinella spp. isolates were identified at the species level. Trichinella spiralis was detected in 9 animals (1.0% of identified infections) as single, double or triple infections; whereas, T. spiralis had been detected in 13.6% and in 14.5% of infected wild animals in the course of the two previous investigations. The reduction of T. spiralis prevalence from 1993-1997 to 2011-2013 is statistically significant (p < 0.001) both per total tested animals and per host species. The results of this study support the hypothesis of spillover from domestic pigs as a source of T. spiralis in wildlife. The eradication of T. spiralis from the domestic cycle in Finland in 2004 has probably established a virtuous cycle reducing the prevalence of this pathogen among wild carnivores. We can expect that within some years and in absence of T. spiralis reintroduction in the domestic habitat, it might even disappear from the Finnish wildlife.

Shodagor Family Strategies : Balancing Work and Family on the Water.

The Shodagor of Matlab, Bangladesh, are a seminomadic community of people who live and work on small wooden boats, within the extensive system of rivers and canals that traverse the country. This unique ecology places particular constraints on family and economic life and leads to Shodagor parents employing one of four distinct strategies to balance childcare and provisioning needs. The purpose of this paper is to understand the conditions that lead a family to choose one strategy over another by testing predictions about socioecological factors that impact the sexual division of labor, including a family's stage in the domestic cycle, aspects of the local ecology, and the availability of alloparents. Results show that although each factor has an impact on the division of labor individually, a confluence of these factors best explains within-group, between-family differences in how mothers and fathers divide subsistence and childcare labor. These factors also interact in particular ways for Shodagor families, and it appears that families choose their economic strategies based on the constellation of constraints that they face. The results of these analyses have implications for theory regarding the sexual division of labor across cultures and inform how Shodagor family economic and parenting strategies should be contextualized in future studies.

Regional level risk factors associated with the occurrence of African swine fever in West and East Africa.

BACKGROUND: African swine fever (ASF) causes severe socio-economic impacts due to high mortality and trade restrictions. Many risk factors of ASF have been identified at farm level. However, understanding the risk factors, especially wild suid hosts, determining ASF transmission at regional level remains limited. METHODS: Based on ASF outbreak data in domestic pigs during 2006-2014, we here tested, separately for West and East Africa, which risk factors were linked to ASF presence at a regional level, using generalized linear mixed models. RESULTS: Our results show that ASF infections in the preceding year was an important predictor for ASF presence in both West and East Africa. Both pig density and human density were positively associated with ASF presence in West Africa. In East Africa, ASF outbreaks in domestic pigs were also correlated with higher percentages of areas occupied by giant forest hogs and by high-tick-risk areas. CONCLUSIONS: Our results suggest that regional ASF risk in East Africa and in West Africa were associated with different sets of risk factors. Regional ASF risk in West Africa mainly followed the domestic cycle, whereas the sylvatic cycle may influence regional ASF risk in East Africa. With these findings, we contribute to the better understanding of the risk factors of ASF occurrence at regional scales that may aid the implementation of effective control measures.

Ecology of Trypanosoma cruzi I genotypes across Rhodnius prolixus captured in Attalea butyracea palms.

Trypanosoma cruzi, the agent of Chagas disease exhibits significant genetic diversity. This parasite is divided into six discrete typing units (DTUs) where T. cruzi I (TcI) is the most widespread in the Americas. TcI genotypes have been associated to domestic and sylvatic cycles of transmission (TcIDom and sylvatic TcI). Due to the importance of the enzootic transmission, we determined the frequency of TcI genotypes present in Rhodnius prolixus captured in different regions of the palm A. butyracea to understand the ecology of the disease and the importance of A. butyracea palms as ecotopes of R. prolixus. Forty A. butyracea palms were sampled (base crown, mid-point and crown) capturing 105 individuals identified as R. prolixus by morphological and molecular barcoding. We conducted molecular detection and typing of T. cruzi across 59 individuals. The results showed that all the insects were infected with TcI; 28.57% were sylvatic TcI, 12.38% TcIDom and 15,24% mixed infections (TcIDom/sylvatic TcI). Statistical analysis showed a similar behavior between TcIDom and mixed infections in the mid-point and at the crown of the palm, being more frequent in the crown, while sylvatic TcI does not seem to have a specific association with any of the sampled areas. These findings are consistent with other studies showing high mobility of the insect vector between different ecotopes, increasing the need to develop improvements in the programs of disease control.

The red fox (Vulpes vulpes) plays a minor role in the epidemiology of the domestic cycle of Trichinella in Romania.

Nematode worms of the genus Trichinella are zoonotic parasites with a worldwide distribution. The majority of the biomass of these nematodes circulates among wildlife, but when humans fail in the proper management of domestic animals and wildlife, Trichinella infections are transmitted from the sylvatic to the domestic environment. Such failures occur in Romania, where a high prevalence of Trichinella spiralis has been detected in domestic pigs. The aim of the present study was to provide data about the prevalence of Trichinella spp. infections in red foxes (Vulpes vulpes) that are hunted in Romanian counties, in which the prevalences of Trichinella spp. infection in backyard and free-ranging pigs range from 0.17 to 2.5%, to determine the role played by this carnivore species in the transmission of the parasite to domestic cycle. A total of 121 animals from 45 hunting grounds of three counties were screened to detect Trichinella spp. larvae by the digestion method. Infections were detected in 26 (21.5%) foxes from 18 (40%) hunting grounds of the three counties (13/67 in Arad, 1/3 in Hunedoara, and 12/51 in Timis). The mean larval density was 10.5 larvae per gram. Of the 25 successfully tested samples, the Trichinella larvae from 24 isolates were identified as T. britovi (96%), and the larvae from one isolate were identified as T. spiralis (4%). No mixed infections were recorded. The present results revealed that the red fox should be considered an important T. britovi reservoir in the sylvatic cycle; in contrast, the detection of only a single T. spiralis-positive isolate suggests that red foxes play a minor role in the epidemiology of the domestic cycle in the investigated area of western Romania.

Retrospective distribution of Trypanosoma cruzi I genotypes in Colombia

Trypanosoma cruzi is the aetiological agent of Chagas disease, which affects approximately eight million people in the Americas. This parasite exhibits genetic variability, with at least six discrete typing units broadly distributed in the American continent. T. cruzi I (TcI) shows remarkable genetic diversity; a genotype linked to human infections and a domestic cycle of transmission have recently been identified, hence, this strain was named TcIDom. The aim of this work was to describe the spatiotemporal distribution of TcI subpopulations across humans, insect vectors and mammalian reservoirs in Colombia by means of molecular typing targeting the spliced leader intergenic region of mini-exon gene. We analysed 101 TcI isolates and observed a distribution of sylvatic TcI in 70% and TcIDom in 30%. In humans, the ratio was sylvatic TcI in 60% and TcIDom in 40%. In mammal reservoirs, the distribution corresponded to sylvatic TcI in 96% and TcIDom in 4%. Among insect vectors, sylvatic TcI was observed in 48% and TcIDom in 52%. In conclusion, the circulation of TcIDom is emerging in Colombia and this genotype is still adapting to the domestic cycle of transmission. The epidemiological and clinical implications of these findings are discussed herein.

Trypanosoma cruzi diversity in the Gran Chaco: mixed infections and differential host distribution of TcV and TcVI.

The transmission cycles of Trypanosoma cruzi in the Gran Chaco are complex networks involving domestic and wild components, whose interrelationships are not well understood. Knowing the circuit of transmission of the different Discrete Typing Units (DTUs) of T. cruzi in the complex environment of the Chaco region is relevant to understanding how the different components (reservoirs, vectors, ecotopes) interact. In the present study we identified the DTUs infecting humans and dogs in two rural areas of the Gran Chaco in Argentina, using molecular methods which avoid parasite culture. Blood samples of humans and dogs were typified by PCR-DNA blotting and hybridization assays with five specific DNA probes (TcI, TcII, TcIII, TcV and TcVI). PCR analyses were performed on seropositive human and dog samples and showed the presence of T. cruzi DNA in 41.7% (98/235) and 53% (35/66) samples, respectively. The identification of infective DTUs was determined in 83.6% (82/98) and 91.4% (32/35) in human and dog samples, respectively. Single infections (36.7% - 36/98) and a previously not detected high proportion of mixed infections (47.9% - 47/98) were found. In a 15.3% (15/98) of samples the infecting DTU was not identified. Among the single infections TcV was the most prevalent DTU (30.6% - 30/98) in human samples; while TcVI (42.8% - 15/35) showed the highest prevalence in dog samples. TcV/TcVI was the most prevalent mixed infection in humans (32.6% - 32/98); and TcI/TcVI (14.3% - 5/35) in dogs. Significant associations between TcV with humans and TcVI with dogs were detected. For the first time, the presence of TcIII was detected in humans from this region. The occurrence of one human infected whit TcIII (a principally wild DTU) could be suggested the emergence of this, in domestic cycles in the Gran Chaco.

Trypanosoma cruzi, the Causal Agent of Chagas Disease: Boundaries between Wild and Domestic Cycles in Venezuela.

Trypanosoma cruzi the etiological agent of American Trypanosomiasis or Chagas disease (ChD) is transmitted by triatomines vectors between mammals including man. T. cruzi has existed for circa 150 Ma in the Americas and nearly 10 million people are currently infected. The overlap between wild and domestic ecotopes where T. cruzi circulates is increasing. Host-parasite interactions have been determined by infection patterns in these cycles, all under natural or laboratorial conditions. This mini-review describes specific parasite niches, such as plant communities or biological corridors between domestic and wild landscapes, in order to help identify risk factors for ChD and define the boundaries between wild and domestic transmission cycles, with an emphasis on research undertaken in Venezuela.