The Role of Scavenging in Disease Dynamics

Optimizing response to an introduction of African swine fever in wild pigs

African swine fever virus (ASFv) is a virulent pathogen that threatens domestic swine industries globally and persists in wild boar populations in some countries. Persistence in wild boar can challenge elimination and prevent disease-free status, making it necessary to address wild swine in proactive response plans. In the U.S., invasive wild pigs are abundant and found across a wide range of ecological conditions that could drive different epidemiological dynamics among populations. Information on size of control areas required to rapidly eliminate ASFv in wild pigs and how this area should change with management constraints and local ecology are needed to optimize response planning. We developed a spatially-explicit disease transmission model contrasting wild pig movement and contact ecology in two ecosystems in southeastern U.S. We simulated ASFv spread and determined optimal response area (reported as radius of a circle) for eliminating ASFv rapidly over a range of detection times (when ASFv is detected relative to true date of introduction), culling capacities (proportion of wild pigs in the culling zone removed weekly), and wild pig densities. Large radii for response areas (14 km) were needed under most conditions but could be shortened with early detection (≤ 8 weeks) and high culling capacities (≥ 15% weekly). Under most conditions ASFv was eliminated in less than 22 weeks using optimal control radii, although ecological conditions with high rates of wild pig movement required higher culling capacities (≥ 10% weekly) for elimination within one year. Results highlight the importance of adjusting response plans based on local ecology and show wild pig movement is a better predictor of optimal response area than numbers of ASFv cases early in the outbreak trajectory. Our framework provides a tool for determining optimal control plans in different areas, guiding expectations of response impacts, and planning resources needed for rapid elimination. This article is protected by copyright. All rights reserved.

Systematic mapping on the importance of vultures in the Indian public health discourse

Vultures are of immense ecological significance to forest and urban ecosystems. These birds play a major role in curbing environmental contamination through scavenging on carcasses. Prevention of spread of diseases is pivotal for public health and is an inexorable economic burden for any country. We present the crucial role vultures can play in disease mitigation and public health by regulating or decreasing the spread of zoonotic diseases. We elaborate examples from three zoonotic diseases; rabies, brucellosis and tuberculosis, which spread among dogs and cattle as well as human population. We establish the viable links in the transmission of these diseases from the infected dead and alive animals to humans and their possible exacerbation in the absence of vultures. These indirect links help formulate the case for increased interventions for disease spread and control along with conservation of these scavengers. Their role as natural and effective cleaners of the environment in the Indian health discourse is of importance because they can reduce the expenses of the government in waste management and maintenance of public health.

The golden jackal (Canis aureus) and the African swine fever pandemic: Its role is controversial but not negligible (a diet analysis study)

Background

In Europe, the African swine fever (ASF) pandemic mostly affects the environmental domain of health, which is a strongly human‐impacted ecosystem. However, the current control strategies focus solely on the wild boar and tend to disregard other epidemiologically relevant elements of the ecosystem.

Objectives

This study investigated the potential impact of the golden jackal on the surveillance effort and disease transmission.

Methods

For this reason, the authors analysed the content of 277 stomachs of this canid species within its westernmost inhabitant population, in order to determine the amount of suid remains, disposed.

Results

The findings confirmed that in a densely populated wild boar habitat, the main diet component of jackals was wild boar all the year round. The jackals disposed of 0.3–0.6 kg/km²/day offals that potentially contained suid remains. On the other hand, the scavenging activity removed the most important target objects on which the passive surveillance of ASF should be based.

Conclusions

This study cannot determine whether canid scavengers positively or negatively influence the control efforts; however, the impact of the jackal should not be disregarded. The results warn the necessity of a multidisciplinary approach to complex epidemiological situations within different ecosystems.

Seroepidemiology of bovine brucellosis in Colombia's preeminent dairy region, and its potential public health impact

A cross-sectional study was conducted to determine the associated factors of brucellosis in Colombia's preeminent dairy region declared in quarantine. A total of 656 samples were collected from cows ≥ 2-year-old from 40 herds. Samples were screened by the Rose Bengal Plate Test, and the Fluorescence Polarized Assay test and Competitive ELISA were used as confirmatory tests. A cow was classified as positive if the screening and both confirmatory tests were positive. A herd was classified as positive if at least one cow was seropositive. The factors associated to seropositivity were tested using a logistic regression model with explanatory variables regarding cattle management, zootechnical parameters, and sanitary practices. The seroprevalence at the animal level was 6.6% (43/656) and at herd level 27.5% (11/40). In the model, five variables explained the animal cases: purchase or animal transfer between owner's farms (OR = 2.79, 95% CI 1.42, 5.49), history of abortion (OR = 4.22, 95% CI 1.91, 9.33), birth of weak calves (OR = 13.77, 95% CI 2.75, 68.91), use of a bull for mating (OR = 9.69, 95% CI 2.23, 42.18), and the vaccination in adulthood (OR = 3.03, 95% CI 1.04.8.78). In the model at the herd level, two variables explained the cases: birth of weak calves (OR = 9.60, 95% CI 1.54, 59.76) and purchase or animal transfer between owner's farms (OR = 7.22, 95% CI 1.03, 50.62). These results justify the need for a quarantine declaration in the region and the implementation of epidemiological studies as a public health measures used to combat outbreak.

Investigation of Cysticercosis bovis prevalence using passive abattoir post-mortem inspection and active administration of structured non-participatory questionnaire to farmers in Botswana

Most government published statistics of C. bovis prevalence in Botswana emanate mainly from records available at the Botswana Meat Commission (BMC), the country's national export abattoir. Although BMC slaughters 44% of Botswana's annual cattle slaughter, prevalence data arising from BMC does not reflect prevalence from lower throughput abattoirs and potential hotspots. Thus, reporting national prevalence rate using solely BMC statistics may not be very informative and reflective of the bigger picture. It therefore became imperative to probe prevalence of bovine cysticercosis using a cross-sectional study through passive abattoir inspection, covering a wider scope (more regions) and some lower throughput abattoirs previously not accounted for. Furthermore, non-participatory interview using structured questionnaires was employed to actively elicit prevalence information directly from meat industry stake holders. Prevalence arising from survey was used to compare and query results from statutory (traditional) passive abattoir method. Abattoir prevalence was 17.17% (SE = 1.70027), and survey prevalence was 42.35%; both of which were higher than published prevalence of 13.5% and BMC prevalence of 10% (SE = 0.006576). Survey method was more holistic than passive abattoir method, by covering more frontiers thus yielding higher prevalence. At p = 025, abattoir and survey prevalence were significantly different from each other. In addition to delimitating novel hotspots in Botswana, this study showed significant difference, p = 0.002 in prevalence within districts and regions. Kalagadi district's prevalence differed significantly from other districts: differed from North East at p = 0.042, Central district at p = 0.002 and Ghanzi at p = 0.004. The results which arise from this methodological approach have been able to provide a more all-inclusive and reliable prevalence rate.