Evolution of Liver Fibrosis During Long-term Experimental Schistosoma japonicum Infection in Pigs

Schistosomiasis japonica, caused by the zoonotic trematode Schistosoma japonicum, is a highly debilitating parasitic disease endemic in China, the Philippines and Indonesia. The disease is a serious threat to public health and a major cause of liver fibrosis in humans. The tissue damage caused by the host tissue reaction to schistosome eggs trapped in the portal system of the liver leads to portal fibrosis and hypertension. The fibrosis is characterised by excessive deposition of extra-cellular matrix (ECM), especially collagen types 1 and 3 in various proportions, in portal areas. The pig is a natural host for S. japonicum and has several anatomical, physiological and immunological similarities with man, which has led to the exploration of the pig as a large animal model of human schistosomiasis japonica. In pigs, pronounced portal and septal fibrosis develops at the early stage of infection, when egg excretion is high and then gradually regresses over time as the pigs undergo self-cure. This makes the pig a useful animal model for studies of the pathogenesis of the development and resolution of liver fibrosis, including any qualitative changes in the ECM that may occur during the infection period.In the present study, liver fibrosis during the course of long-term S. japonicum infection in pigs was investigated. Three groups of pigs were infected with 1000 S. japonicum cercariae and necropsied at 8, 16 and 24 weeks post infection (p.i.). Parasitological variables included faecal egg and miracidial counts and liver tissue egg counts(TEC). The degree of fibrosis was assessed in Masson’s trichrome-stained liver sections, using both semi-quantitative histopathological scoring and quantitative area measurement by image analysis. The number of perioval granulomas per area unit in the same sections was determined. Collagen type 1 was detected by immunohistochemistry and the area fraction in selected areas of interlobular septa was measured by image analysis. The relationship between fibrosis and parasitological variables was investigated.Faecal egg and miracidial counts peaked at 8 weeks p.i. and declined rapidly thereafter to low levels at 24 weeks p.i. Liver TEC and granuloma density were also highest at 8 weeks p.i. and decreased at the later time points. The liver lesions were characterised by perioval granulomas, diffuse inflammatory cell infiltration, and portal and septal fibrosis. Scores for both portal and septal fibrosis were highest at 8 weeks p.i. and were reduced at the later time points, and similar results were obtained for the area of fibrosis. Collagen type 1 was present in portal and septal areas in proportion to the degree of fibrosis in the infected pigs. The area fraction for collagen type 1 in septa was significantly higher in infected than in control pigs, but no difference was found between the different time points in infected pigs. There was a correlation between the area of fibrosis and faecal miracidial counts and between granuloma density and faecal egg counts. Fibrosis was strongly correlated with granuloma density, but not with liver TEC. The two methods used for assessment of liver fibrosis were found to be well correlated.In conclusion, this study confirmed the results from other studies that marked liver fibrosis develops at the acute stage and is reduced at later stages of S. japonicum infection in pigs, and that the degree of fibrosis is related to granuloma density in the liver. The results suggest that faecal egg excretion could be used as a marker of liver pathology. Quantitative image analysis gave comparable results to semi-quantitative histopathological scoring and is thus a useful, additional tool for assessment of the degree of liver fibrosis in this animal model. Finally, the study showed that the area fraction of collagen type 1 in fibrous septa was increased in the infected pigs, but did not change in connection with the resolution of fibrosis that occurred during the course of infection

Ovine Paratuberculosis: A Seroprevalence Study in Dairy Flocks Reared in the Marche Region, Italy

In order to fulfil the seroprevalence gap on Mycobacterium avium subsp. paratuberculosis infection in ovine dairy farms of Marche region (central Italy), a stratified study was carried out on 2086 adult female sheep randomly chosen from 38 herds selected in Ancona and Macerata provinces. 73.7% flocks resulted infected by a commercial ELISA test (Pourquier, France), with a mean seroprevalence of 6.29% of sampled sheep in both provinces. A higher number of MAP seropositive ewes was recorded in the large herds' consistence than in the small and medium herds' consistence (P = 0.0269), and a greater percentage of infected sheep was obtained among female at early/late than in peak lactation stage (P = 0.0237). MAP infection was confirmed in 12.6% of infected farms by faecal culture. The true sheep-level seroprevalence was 15.1% ± 7.3%

Bovine tuberculosis antemortem diagnostic test agreement and disagreement in a naturally infected African cattle population.

The interferon-gamma (IFN-γ) assay and single comparative cervical skin test (SCITT) are used to estimate bovine tuberculosis (bTB) prevalence globally. Prevalence estimates of bTB, caused by Mycobacterium bovis, are poorly quantified in many Sub-Saharan African (SSA) cattle populations. Furthermore, antemortem diagnostic performance can vary at different stages of bTB pathogenesis and in different cattle populations. In this study, we aim to explore the level of agreement and disagreement between the IFN-γ assay and SCITT test, along with the drivers for disagreement, in a naturally infected African cattle population. In, 2013, a pastoral cattle population was sampled using a stratified clustered cross-sectional study in Cameroon. A total of 100 pastoral cattle herds in the North West Region (NWR) and the Vina Division (VIN) were sampled totalling 1,448 cattle. Individual animal data and herd-level data were collected, and animals were screened using both the IFN-γ assay and SCITT. Serological ELISAs were used to detect exposure to immunosuppressing co-infections. Agreement analyses were used to compare the performance between the two bTB diagnostic tests, and multivariable mixed-effects logistic regression models (MLR) were developed to investigate the two forms of IFN-γ assay and SCITT binary disagreement. Best agreement using the Cohen's κ statistic, between the SCITT (>2 mm) and the IFN-γ assay implied a ‘fair-moderate' agreement for the NWR [κ = 0.42 (95%CI: 0.31–0.53)] and ‘poor-moderate' for the VIN [κ = 0.33 (95% CI: 0.18–0.47)]. The main test disagreement was the animals testing positive on the IFN-γ assay and negative by the SCITT. From MLR modeling, adults (adults OR: 7.57; older adults OR = 7.21), females (OR = 0.50), bovine leucosis (OR = 2.30), and paratuberculosis positivity (OR = 6.54) were associated with IFN-γ-positive/SCITT-negative disagreement. Subsets to investigate diagnostic test disagreement for being SCITT-positive and IFN-γ-negative also identified that adults (adults OR = 15.74; older adults OR = 9.18) were associated with IFN-γ-negative/SCITT-positive disagreement. We demonstrate that individual or combined use of the IFN-γ assay and SCITT can lead to a large variation in bTB prevalence estimates. Considering that animal level factors were associated with disagreement between the IFN-γ assay and SCITT in this study, future work should further investigate their impact on diagnostic test performance to develop the approaches to improve SSA prevalence estimates

The evolution and phylodynamics of serotype A and SAT2 foot-and-mouth disease viruses in endemic regions of Africa

Abstract Foot-and-mouth disease (FMD) is a major livestock disease with direct clinical impacts as well as indirect trade implications. Control through vaccination and stamping-out has successfully reduced or eradicated the disease from Europe and large parts of South America. However, sub-Saharan Africa remains endemically affected with 5/7 serotypes currently known to be circulating across the continent. This has significant implications both locally for livestock production and poverty reduction but also globally as it represents a major reservoir of viruses, which could spark new epidemics in disease free countries or vaccination zones. This paper describes the phylodynamics of serotypes A and SAT2 in Africa including recent isolates from Cameroon in Central Africa. We estimated the most recent common ancestor for serotype A was an East African virus from the 1930s (median 1937; HPD 1922–1950) compared to SAT2 which has a much older common ancestor from the early 1700s (median 1709; HPD 1502–1814). Detailed analysis of the different clades shows clearly that different clades are evolving and diffusing across the landscape at different rates with both serotypes having a particularly recent clade that is evolving and spreading more rapidly than other clades within their serotype. However, the lack of detailed sequence data available for Africa seriously limits our understanding of FMD epidemiology across the continent. A comprehensive view of the evolutionary history and dynamics of FMD viruses is essential to understand many basic epidemiological aspects of FMD in Africa such as the scale of persistence and the role of wildlife and thus the opportunities and scale at which vaccination and other controls could be applied. Finally we ask endemic countries to join the OIE/FAO supported regional networks and take advantage of new cheap technologies being rolled out to collect isolates and submit them to the World Reference Laboratory

Cattle transhumance and agropastoral nomadic herding practices in central Cameroon

Abstract Background In sub-Saharan Africa, livestock transhumance represents a key adaptation strategy to environmental variability. In this context, seasonal livestock transhumance also plays an important role in driving the dynamics of multiple livestock infectious diseases. In Cameroon, cattle transhumance is a common practice during the dry season across all the main livestock production zones. Currently, the little recorded information of the migratory routes, grazing locations and nomadic herding practices adopted by pastoralists, limits our understanding of pastoral cattle movements in the country. GPS-tracking technology in combination with a questionnaire based-survey were used to study a limited pool of 10 cattle herds from the Adamawa Region of Cameroon during their seasonal migration, between October 2014 and May 2015. The data were used to analyse the trajectories and movement patterns, and to characterize the key animal health aspects related to this seasonal migration in Cameroon. Results Several administrative Regions of the country were visited by the transhumant herds over more than 6 months. Herds travelled between 53 and 170 km to their transhumance grazing areas adopting different strategies, some travelling directly to their destination areas while others having multiple resting periods and grazing areas. Despite their limitations, these are among the first detailed data available on transhumance in Cameroon. These reports highlight key livestock health issues and the potential for multiple types of interactions between transhumant herds and other domestic and wild animals, as well as with the formal livestock trading system. Conclusion Overall, these findings provide useful insights into transhumance patterns and into the related animal health implications recorded in Cameroon. This knowledge could better inform evidence-based approaches for designing infectious diseases surveillance and control measures and help driving further studies to improve the understanding of risks associated with livestock movements in the region

Knowledge of Bovine Tuberculosis, Cattle Husbandry and Dairy Practices amongst Pastoralists and Small-Scale Dairy Farmers in Cameroon

BACKGROUND:Control of bovine tuberculosis (bTB) and zoonotic tuberculosis (zTB) has relied upon surveillance and slaughter of infected cattle, milk pasteurisation and public health education. In Cameroon, like many other sub-Saharan African countries, there is limited understanding of current cattle husbandry or milk processing practices or livestock keepers awareness of bTB. This paper describes husbandry and milk processing practices within different Cameroonian cattle keeping communities and bTB awareness in comparison to other infectious diseases. STUDY DESIGN:A population based cross-sectional sample of herdsmen and a questionnaire were used to gather data from pastoralists and dairy farmers in the North West Region and Vina Division of Cameroon. RESULTS:Pastoralists were predominately male Fulanis who had kept cattle for over a decade. Dairy farmers were non-Fulani and nearly half were female. Pastoralists went on transhumance with their cattle and came into contact with other herds and potential wildlife reservoirs of bTB. Dairy farmers housed their cattle and had little contact with other herds or wildlife. Pastoralists were aware of bTB and other infectious diseases such as foot-and-mouth disease and fasciolosis. These pastoralists were also able to identify clinical signs of these diseases. A similar proportion of dairy farmers were aware of bTB but fewer were aware of foot-and-mouth and fasciolosis. In general, dairy farmers were unable to identify any clinical signs for any of these diseases. Importantly most pastoralists and dairy farmers were unaware that bTB could be transmitted to people by consuming milk. CONCLUSIONS:Current cattle husbandry practices make the control of bTB in cattle challenging especially in mobile pastoralist herds. Routine test and slaughter control in dairy herds would be tractable but would have profound impact on dairy farmer livelihoods. Prevention of transmission in milk offers the best approach for human risk mitigation in Cameroon but requires strategies that improved risk awareness amongst producers and consumers

The role of viruses, bacteria, and Mycobacterium avium subspecies paratuberculosis infection in the etiology of Diabetes Mellitus.

It is the current opinion that pathogens, such as bacteria and viruses, could contribute to the development of Type 1 Diabetes (T1D) in susceptible individuals on the base of epidemiological associations and direct isolation of micro-organisms. Moreover prospective studies supposed chronic inflammation as a risk factor for Type 2 Diabetes (T2D). Human enteroviruses (HEV) emerged as prime suspects, because of detection frequencies around clinical onset and their ability to rapidly trigger hyperglycemia. Arguments in favour and opposed to a viral involvement in the pathogenesis of T1D have been proposed. Controversial is the role of Helicobacter pilori in the diabetes onset too. Several Authors from the Netherlands, Italy, Turkey, and Africa reported a positive association between H. pylori infection and T2D but, whether H. pylori could induce a defect in insulin secretion remains speculative. Recent findings linked diabetes to Crohn's disease, since they found Mycobacterium avium subspecies paratuberculosis (Map) bacteremia involved with autoimmune diabetes. Its association with T1D has been recently proposed but specific immunoassays did not confirm the association of Map with T2D. The zoonotic potential of Map has been debated for almost a century due to apparent clinical and pathological similarities between Johne’s Disease (JD) in ruminants and Crohn’s Disease (CD) in humans. Paratuberculosis is a chronic, wasting and incurable granulomatous enteritis that occurs worldwide with increasing frequency. Due to the negative impact of JD on animal production and the potential public health risk through the consumption of milk contaminated with Map, government agencies are considering control programs and targeted microbial testing of milk at processing. Consumption of contaminated milk early in life is a recognized risk factor in the development of these diseases; moreover the ingestion of contaminated cheese manufactured from raw ovine and bovine milk might lead to transmission of Map to humans. Furthermore, the effect of time/temperature conditions during pasteurization on the viability of Map provide firm evidence that this organism is sometimes able to survive to commercial milk pasteurization. Nowadays clinical studies are deciphering the role of chronic bacterial infection in the development of autoimmune diseases such as T1D by rapidly identification of infectious agents, such as Map in diabetic patients. Thus, a comprehensive understanding of Map prevalence, incidence and epidemiological patterns in animals is of tangible value to facilitate the design of prevention and control programmes to reduce Map infection and subsequent transmission to humans

Epidemiology of African Swine Fever in piggeries in the Center, South and South-West of Cameroon

African Swine Fever (ASF) is enzootic in Cameroon. A cross-sectional study was conducted in the center, south and south-west regions of Cameroon in order to determine: the knowledge, skills and practices at risk of pig breeders; the prevalence of the disease in piggeries; the genome of the circulating virus. A total of 684 blood samples were collected in 209 farms for RT-PCR and ELISA analyses at the National Veterinary Laboratory (LANAVET) annex in Yaoundé. Prevalences of 15.2% (95CI: 12.5-17.9%) by ELISA, 23.8% (95CI: 20.6-27.0%) by RT-PCR, and 15.2% (95CI: 12.5-17.9%) by ELISA-PCR, were recorded. Of the farmers surveyed, 90% knew about the ASF and 55.3% have already experienced it. The 47.4% of them would not be able to recognize ASF if it occurred and, according to them, the risk of the disease introduction in farms would be 32% linked to the animal health personnel who work on farms. Molecular characterization revealed that only ASF genotype-I variable 19T-RSs is circulating. ASF is still hovering at a risky rate over the pig sector of Cameroon. The control of ASF needs an epidemiological surveillance, a better involvement of all stakeholders, sensitization of breeders and an effective State support for producers