Spatial clusters of human and livestock anthrax define high-risk areas requiring intervention in Lao Cai Province, Vietnam 1991-2022.

Anthrax, a widespread zoonosis in low and middle-income countries with low disease awareness and insufficient livestock vaccination coverage, has been known in Lao Cai Province in northern Vietnam for years before its apparent absence in 2009, which requires investigation as this infection is frequently reported from neighbouring provinces and countries. We aimed to describe the seasonal patterns of anthrax (1991-2008), compare livestock anthrax vaccine coverage to disease occurrence (1991- 2022), and delineate the high-risk areas to inform local disease surveillance in the province. We illustrated the seasonal pattern of anthrax and provided a comparison between livestock vaccine coverage and disease occurrence by purely spatial SaTScan (Poisson model, 25% population at risk) to detect spatial clusters of human and livestock anthrax using population derived from zonal statistics routines. The number of cases, crude cumulative incidence, and spatial clusters of human and livestock anthrax were mapped in QGIS. Results indicate peak anthrax incidence from May to October. Buffalo, domestic cattle, and horses accounted for 75% of total animal cases. Horse anthrax was more common in Lao Cai than in its neighbours and often occurred in years with human mortality. Vaccination covered less than 30% of the livestock population. We found an apparent pattern where anthrax was controlled from 1998-2003 with higher vaccine coverage (>20%) and identified spatial clusters of human and livestock anthrax in Muong Khuong, Bao Thang, and Bac Ha districts of Lao Cai. The local public health and veterinary agencies are recommended to revisit the high-risk areas and communicate with neighbouring provinces for a regional approach to anthrax surveillance and control.

LETHAL TOXIN NEUTRALIZING ANTIBODY RESPONSE INDUCED FOLLOWING ORAL VACCINATION WITH A MICROENCAPSULATED BACILLUS ANTHRACIS STERNE STRAIN 34F2 VACCINE PROOF-OF-CONCEPT STUDY IN WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS).

Improved methods are needed to prevent wildlife deaths from anthrax. Caused by Bacillus anthracis, naturally occurring outbreaks of anthrax are frequent but unpredictable. The commercially available veterinary vaccine is labeled for subcutaneous injection and is impractical for large-scale wildlife vaccination programs; therefore, oral vaccination is the most realistic method to control and prevent these outbreaks. We reported the induction of an anthrax-specific lethal toxin (LeTx) neutralizing antibody response in mice following oral vaccination with alginate microcapsules containing B. anthracis Sterne strain 34F2 spores, coated with poly-L-lysine (PLL) and vitelline protein B (VpB). We continued evaluating our novel vaccine formulation through this proof-of-concept study in white-tailed deer (WTD; Odocoileus virginianus; n = 9). We orally vaccinated WTD via needle-free syringe with three formulations of the encapsulated vaccine: 1) PLL-VpB-coated microcapsules with 107-8 spores/ml (n = 5), 2) PLL-VpB-coated microcapsules with 109-10 spores/ml (n = 2), and 3) PLL-coated microcapsules with 109-10 spores/ml (n = 2). Although the limited sample sizes require continued experimentation, we observed an anthrax-specific antibody response in WTD serum following oral vaccination with PLL-coated microcapsules containing 109 spores/ ml. Furthermore, this antibody response neutralized anthrax LeTx in vitro, suggesting that continued development of this vaccine may allow for realistic wildlife anthrax vaccination programs.

Modelling climate change impacts on the spatial distribution of anthrax in Zimbabwe.

BACKGROUND: In Zimbabwe, anthrax is endemic with outbreaks being reported almost annually in livestock, wildlife, and humans over the past 40 years. Accurate modelling of its spatial distribution is key in formulating effective control strategies. In this study, an Ensemble Species Distribution Model was used to model the current and future distribution of anthrax occurrence in Zimbabwe. METHODS: Bioclimatic variables derived from the Beijing Climate Centre Climate System Model were used to model the disease. Collinearity testing was conducted on the 19 bioclimatic variables and elevation to remove redundancy. Variables that had no collinearity were used for anthrax habitat suitability modelling. Two future climate change scenarios for different Representative Concentration Pathways (RCP), RCP4.5 and RCP8.5 were used. Model evaluation was done using true skill, Kappa statistics and receiver operating characteristics. RESULTS: The results showed that under current bioclimatic conditions, eastern and western districts of Zimbabwe were modelled as highly suitable, central districts moderately suitable and southern parts marginally suitable for anthrax occurrence. Future predictions demonstrated that the suitable (8%) and highly suitable (7%) areas for anthrax occurrence would increase under RCP4.5 scenario. In contrast, a respective decrease (11%) and marginal increase (0.6%) of suitable and highly suitable areas for anthrax occurrence were predicted under the RCP8.5 scenario. The percentage contribution of the predictors varied for the different scenarios; Bio6 and Bio18 for the current scenario, Bio2, Bio4 and Bio9 for the RCP4.5 and Bio3 and Bio15 for the RCP8.5 scenarios. CONCLUSIONS: The study revealed that areas currently suitable for anthrax should be targeted for surveillance and prevention. The predicted future anthrax distribution can be used to guide and prioritise surveillance and control activities and optimise allocation of limited resources. In the marginally to moderately suitable areas, effective disease surveillance systems and awareness need to be put in place for early detection of outbreaks. Targeted vaccinations and other control measures including collaborative 'One Health' strategies need to be implemented in the predicted highly suitable areas. In the southern part where a high decrease in suitability was predicted, continued monitoring would be necessary to detect incursions early.

Environmental relationships and anthrax epidemiology: field experiences of host resistance as opposed to dose-dependent experiments.

Even though anthrax is a disease of antiquity that has been studied for centuries, serious concerns have been raised about our understanding of its epidemiology. Since the 1960s, we have based the epidemiology of anthrax on the results of dose-dependent experiments, especially those involving cattle at that time. In this species the experiments demonstrated that the severity of infection was dependent upon the numbers of Bacillus anthracis spores ingested. The opinion was that ingesting only a few spores would be insufficient to cause an apparent infection; any infection that resulted would be latent (i.e., unrecognized). Based on the results of these experiments, it was accepted that the ingestion of large numbers of spores was the source of infection for hundreds of anthrax outbreaks. However, many investigations of both human and animal anthrax outbreaks have failed to identify sources of large numbers of spores, suggesting that these outbreaks are only rarely a consequence of ingestion or inhalation of large quantities of spores. This opinion piece builds upon the indirect evidence previously presented in an article focused on the existence of latent infections. Much of the evidence for the existence of latent infections was predicated upon a reduction of host resistance, which revealed how latent infections could be a source of more severe forms of the infection. That is, a latent infection can be the source of a severe infection, but the cause of the severe infection is the reduced host resistance. That first article concentrated on the arguments for latent infections, while this article concentrates on the arguments for host resistance. Host resistance is virtually impossible to measure objectively in the field. To provide a subjective measure of host resistance during anthrax outbreaks, we suggest the use of the opinions of livestock owners and or their veterinary practitioners and or field workers during investigations of anthrax outbreaks. When veterinary personal work in the field they are much like field biologists. In some ways field biologists better appreciate environmental factors, population ecology and other perspectives that are of use to epidemiologists. The more diverse the information the better the epidemiology is understood. To this effect we present our personal anecdotal and theoretical ideas from our experiences as well as a collection of bibliographic observations from others'. Our conclusions are that a combination of latent infections and reduced host resistance based on the host's relationship with its environment would better explain the epidemiology of severe infections in anthrax outbreaks for which large quantities of spores have not been located. This applies especially if the area has a history of the disease and/or if necropsies have shown the presence of latent infections in otherwise normal animals in the area and/or if environmental conditions are considered stressful and include intense insect activity.

Outbreak of Anthrax in Livestock with Human Occupational Exposures - Minnesota, 2023.

In July 2023, the Minnesota Department of Health (MDH) was notified of possible occupational exposures to anthrax during an outbreak in animals. In consultation with the Centers for Disease Control and Prevention, MDH epidemiologists created a questionnaire that assessed exposure risks and helped determine individual illness monitoring and antibiotic post-exposure prophylaxis needs. This investigation and the resources developed for it could be useful in future scenarios where there are occupational exposures to naturally occurring anthrax.

Spatial epidemiology of human anthrax in Son La province, Vietnam, 2003-2022.

AIMS: Anthrax is reported with frequency but poorly understood in Southeast Asian countries including Vietnam. In Vietnam, anthrax surveillance is national. However, case detection, prevention, and control are implemented locally at the provincial level. Here, we describe the epidemiological characteristics, identify spatial clusters of human anthrax, and compare the variation in livestock anthrax vaccine coverage to disease incidence in humans and livestock using historical data in Son La province, Vietnam (2003-2020). METHODS AND RESULTS: Most human cases occurred between April and September. Most of the patients were male, aged 15-54 years old. The human cases were mainly reported by public district hospitals. There was a delay between disease onset and hospitalization of ~5 days. We identified spatial clusters of high-high incidence communes in the northern communes of the province using the local Moran's I statistic. The vaccine coverage sharply decreased across the study period. The province reported sporadic human anthrax outbreaks, while animal cases were only reported in 2005 and 2022. CONCLUSIONS: These results suggest underreporting for human and livestock anthrax in the province. Intersectoral information sharing is needed to aid livestock vaccination planning, which currently relies on reported livestock cases. The spatial clusters identify areas for targeted surveillance and livestock vaccination, while the seasonal case data suggest prioritizing vaccination campaigns for February or early March ahead of the April peak. A regional approach for studying the role of livestock trading between Son La and neighbouring provinces in anthrax occurrence is recommended.

Combatting anthrax outbreaks across Nigeria's national land borders: need to optimize surveillance with epidemiological surveys.

BACKGROUND: Anthrax is a non-contagious zoonotic disease caused by the Gram-positive, spore-forming bacterium Bacillus anthracis. Infection is common in livestock and wild animals such as cattle, goats, sheep, camels, and antelopes. In humans, anthrax may occur after contact with contaminated carcasses or animal products like milk and meat. The best method to prevent anthrax in people is to ensure livestock are vaccinated, which significantly limits the risk of zoonotic spread to humans. However, the rate of vaccination of domesticated animals kept by nomadic pastoralists in West Africa is low. These groups regularly cross over national boundaries with their grazing herds. Nigeria is a country that historically has done comparatively well to contain this public health threat. However, in 2023 several outbreaks of human disease appear linked to the consumption of anthrax-contaminated animal products brought into Nigeria by pastoralists from neighboring countries. Clinical manifestations include skin sores or ulcers, nausea, vomiting, and fever. This article aims to raise awareness of recent outbreaks of anthrax in West Africa and to call for a renewed focus on measures to combat this neglected public health concern to the region. MAIN BODY: The imperative to pinpoint pivotal issues relating to the ongoing emergence of anthrax cases in Nigeria cannot be overstated. By delving into the prevalence of anthrax in both livestock and human populations residing along Nigeria's borders, unraveling the genetic diversity and potential sources of B. anthracis strains, and identifying the primary animal host(s) responsible for transmission, we stand to enhance our understanding of this critical issue. Furthermore, investigating the multifaceted factors contributing to anthrax transmission, assessing community knowledge and practices, mapping common migratory routes of pastoralists, and formulating targeted intervention strategies tailored to the challenges of border communities, are each crucial steps towards effective control and prevention. CONCLUSION: Closing these knowledge gaps on anthrax is not only essential for safeguarding both animal and human health but also for fostering sustainable and resilient communities. Addressing research questions on these interdisciplinary concerns will undoubtedly pave the way for informed decision-making, proactive measures, and a more secure future for Nigeria and its border regions.

Molecular characterization of an outbreak-involved Bacillus anthracis strain confirms the spillover of anthrax from West Africa.

BACKGROUND: Anthrax, a zoonotic disease caused by the spore-forming bacterium Bacillus anthracis, remains a major global public health concern, especially in countries with limited resources. Sierra Leone, a West African country historically plagued by anthrax, has almost been out of report on this disease in recent decades. In this study, we described a large-scale anthrax outbreak affecting both animals and humans and attempted to characterize the pathogen using molecular techniques. METHODS: The causative agent of the animal outbreak in Port Loko District, Sierra Leone, between March and May 2022 was identified using the nanopore sequencing technique. A nationwide active surveillance was implemented from May 2022 to June 2023 to monitor the occurrence of anthrax-specific symptoms in humans. Suspected cases were subsequently verified using quantitative polymerase chain reaction. Full-genome sequencing was accomplished by combining long-read and short-read sequencing methods. Subsequent phylogenetic analysis was performed based on the full-chromosome single nucleotide polymorphisms. RESULTS: The outbreak in Port Loko District, Sierra Leone, led to the death of 233 animals between March 26th and May 16th, 2022. We ruled out the initial suspicion of Anaplasma species and successfully identified B. anthracis as the causative agent of the outbreak. As a result of the government's prompt response, out of the 49 suspected human cases identified during the one-year active surveillance, only 6 human cases tested positive, all within the first month after the official declaration of the outbreak. The phylogenetic analysis indicated that the BaSL2022 isolate responsible for the outbreak was positioned in the A.Br.153 clade within the TransEuroAsian group of B. anthracis. CONCLUSIONS: We successfully identified a large-scale anthrax outbreak in Sierra Leone. The causative isolate of B. anthracis, BaSL2022, phylogenetically bridged other lineages in A.Br.153 clade and neighboring genetic groups, A.Br.144 and A.Br.148, eventually confirming the spillover of anthrax from West Africa. Given the wide dissemination of B. anthracis spores, it is highly advisable to effectively monitor the potential reoccurrence of anthrax outbreaks and to launch campaigns to improve public awareness regarding anthrax in Sierra Leone.

Anthrax in one health in Southern and Southeastern Europe - the effect of climate change?

Anthrax is a serious infection caused by Bacillus anthracis. The anthracis spores are highly resistant and can persist in the environment for several decades. Therefore, anthrax is considered a global health threat affecting wildlife, livestock, and the general public. The resistance mechanism is influenced not only by the environment or the ecological niche but also by virulence factors. In the last 10 years the Southern and Southeastern Europe have been confronted with this threat. Recently, there have been 8 human anthrax cases reported in Croatia (2022), and 4 cases in Romania (2023). Moreover, this incident and the COVID situation could be a starting point to encourage researchers to raise the alarm. On the other hand, climate change is causing glaciers to melt and land to thaw, and many wetlands and swampy areas are being drained. It should not be forgotten that epidemiological and epizootic threats significantly affect the country's economic development. The Covid-19 epidemic best illustrates these threats.

In Vitro Protection and Titer Duration of Anthrax-Specific Antibodies Following Subcutaneous Vaccination of White-tailed Deer (Odocoileus virginianus) with Bacillus anthracis Sterne 34F2 Strain Spores.

Outbreaks of anthrax, caused by the soilborne bacterium Bacillus anthracis, are a continuous threat to free-ranging livestock and wildlife in enzootic regions of the United States, sometimes causing mass mortalities. Injectable anthrax vaccines are commercially available for use in livestock, and although hand injection is not a cost- or time-effective long-term management plan for prevention in wildlife, it may provide a tool for managers to target selectively animals of high conservation or economic value. Vaccine-induced anthrax-specific antibody responses have been reported previously in white-tailed deer (Odocoileus virginianus), but the protective nature was not determined. In this study, five white-tailed deer were subcutaneously vaccinated with one dose (1 mL) of the Anthrax Spore Vaccine. Eight blood collections by jugular venipuncture were conducted over 146 d to measure the anthrax-specific antibody response in each deer's serum over time. Antibodies were first detected by ELISA and later with toxin neutralization assays to estimate in vitro protection. Average peak absorbance by ELISA occurred at 14 d postvaccination, whereas average peak in vitro protection occurred at 28 d postvaccination. Observed in vitro protection on average for white-tailed deer after this single-dose vaccination protocol lasted 42-56 d postvaccination, although three individuals still maintained lethal toxin-neutralizing serum antibody titers out to 112 d postvaccination. Vaccination responses were variable but effective to some degree in all white-tailed deer.

Spatial analysis of human and livestock anthrax in Lai Chau province, Vietnam (2004-2021).

Anthrax is reported globally with varying disease intensity and seasonality among countries. In Vietnam, anthrax epidemiology and ecology remain understudied. We used historical data of human and livestock anthrax from 2004 to 2021 in Lai Chau province, to identify spatial clusters of human and livestock anthrax, describe epidemiological characteristics, and compare livestock anthrax vaccine coverage to human and livestock disease incidence. Local Moran's I (LISA) using spatial Bayes smoothed commune-level cumulative incidence (per 10,000) for the study period, epidemiological descriptive statistics, livestock vaccine coverage data, and annual incidence rates (per 10,000) at provincial level were used. LISA identified a human anthrax hotspot (high-high) in the southeast which did not overlap spatially with livestock anthrax hotspots in southeastern and northeastern communes. Most human cases were male, aged 15-59 years, handled sick animals, and/or consumed contaminated meat. Almost all cases were reported by grassroot health facilities with a delay of 6.3 days between exposure and case notification to the national surveillance system. 80 % of human cases were reported from June-October. The increase in disease incidence occurred shortly after livestock anthrax vaccine coverage decreased. This study informs vaccination strategy and targeted surveillance and control measures in newly identified high-risk areas and seasons of anthrax.

An integrated model for anthrax-free zone development in developing countries.

Anthrax is more prevalent in impoverished nations and those without veterinarian public health initiatives. A comprehensive strategy was pursued to build an anthrax-free model in which there would be no anthrax. The strategy included routine vaccination, increased public awareness, rapid confirmation, and prompt disposal, as well as the establishment of an effective surveillance system, the development of an emergency prevention system, the enforcement of regulations, and the improvement of collaboration between human health and veterinary services. From 2017 through 2020, several initiatives including both social and laboratory activities were performed. After strictly applying the study's procedures, it was determined that the vast majority of community people (97.5%) were knowledgeable of the disease's nature, prevalence, significance to public health, and treatment in the study area. The farmers' risky practices and attitudes about the killing of sick livestock decreased dramatically (85%). The vaccination rate climbed from 40% to 85%, and the proportion of farmers who can presumptively identify anthrax based on its prominent clinical symptoms rose from 30% to 85%. A confirmation methodology based on PCR was implemented. A geographical map depicting the green and dangerous pastureland was created. The formation of a steering group to assess the progress of scientific activity. Locals established a slaughterhouse in that location, where individuals slaughtered their animals following veterinary examination and strictly followed drug withdrawal period. The contaminated area has been free of anthrax infection for four years as a consequence of these efforts. There also reduction of antibiotic used due to mass awareness. The study indicated that the model is an efficient, effective, and appropriate technique for establishing an anthrax-free zone where no anthrax outbreaks would occur. It could be replicated in any part of the world where socioeconomic and geographical conditions are similar.

Spatial and phylogenetic patterns reveal hidden infection sources of Bacillus anthracis in an anthrax outbreak in Son La province, Vietnam.

Bacillus anthracis, the bacterial cause of anthrax, is a zoonosis affecting livestock and wildlife often spilling over into humans. In Vietnam, anthrax has been nationally reportable since 2015 with cases occurring annually, mostly in the northern provinces. In April 2022, an outbreak was reported in Son La province following the butchering of a water buffalo, Bubalus bubalis. A total of 137 humans from three villages were likely exposed to contaminated meat from the animal. Early epidemiological investigations suggested a single animal was involved in all exposures. Five B. anthracis isolates were recovered from human clinical cases along with one from the buffalo hide, another from associated maggots, and one from soil at the carcass site. The isolates were whole genome sequenced, allowing global, regional, and local molecular epidemiological analyses of the outbreak strains. All recovered B. anthracis belong to the A.Br.001/002 lineage based on canonical single nucleotide polymorphism analysis (canSNP). Although not previously identified in Vietnam, this lineage has been identified in the nearby countries of China, India, Indonesia, Thailand, as well as Australia. A twenty-five marker multi-locus variable number tandem repeat analysis (MLVA-25) was used to investigate the relationship between human, soil, and buffalo strains. Locally, four MLVA-25 genotypes were identified from the eight isolates. This level of genetic diversity is unusual for the limited geography and timing of cases and differs from past literature using MLVA-25. The coupled spatial and phylogenetic data suggest this outbreak originated from multiple, likely undetected, animal sources. These findings were further supported by local news reports that identified at least two additional buffalo deaths beyond the initial animal sampled in response to the human cases. Future outbreak response should include intensive surveillance for additional animal cases and additional molecular epidemiological traceback to identify pathogen sources.

Whole genome sequencing of Bacillus anthracis isolated from animal in the 1960s, Brazil, belonging to the South America subclade.

Bacillus anthracis causes anthrax disease and can affect humans and other animals. This zoonotic disease has an impact on the economic and health aspects. B. anthracis population is divided into three major clades: A (with worldwide distribution), B, and C (restricted to specific regions). Anthrax is most common in agricultural regions of central and southwestern Asia, sub-Saharan Africa, Southern and Eastern Europe, the Caribbean, and Central and South America. Here, we sequenced by short and long reads technologies to generate a hybrid assembly of a lineage of B. anthracis recovered from animal source in the 1960s in Brazil. Isolate identification was confirmed by phenotypic/biochemical tests and MALDI-TOF MS. Antimicrobial susceptibility was performed by in-house broth microdilution. B. anthracis IAL52 was susceptible to penicillin, amoxicillin, doxycycline, levofloxacin, and tetracycline but non-susceptible to ciprofloxacin. IAL52 was classified as sequence type ST2, clade A.Br.069 (V770 group). Sequencing lineages of B. anthracis, especially from underrepresented regions, can help determine the evolution of this critical zoonotic and virulent pathogen.

Incidence and Spatial distribution of Human and Livestock Anthrax in Cao Bang Province, Vietnam (2004-2020).

Specific knowledge on the distribution of anthrax, a zoonosis caused by Bacillus anthracis, in Southeast Asia, including Vietnam, remains limited. In this study, we describe disease incidence and spatial distribution of human and livestock anthrax using spatially smoothed cumulative incidence from 2004 to 2020 in Cao Bang province, Vietnam. We employed the zonal statistics routine a geographic information system (GIS) using QGIS, and spatial rate smoothing using spatial Bayes smoothing in GeoDa. Results showed higher incidence of livestock anthrax compared with human anthrax. We also identified co-occurrence of anthrax in humans and livestock in northwestern districts and the province center. Livestock anthrax vaccine coverage was <6% and not equally distributed among the districts of Cao Bang province. We provide implications for future studies and recommend improving disease surveillance and response through data sharing between human and animal health sectors.

Case-control study of human anthrax outbreak investigation in farta woreda, South Gondar, Northwest Ethiopia.

BACKGROUND: Anthrax is a zoonotic disease caused by the Bacillus anthracis bacteria, which is one of the top five important livestock diseases and the second top priority zoonotic disease, next to rabies, in Ethiopia, which remains a major problem for animals and public health in Ethiopia. This study was conducted to verify the existence of the outbreak, determine risk factors, and implement measures to control the anthrax outbreak in Farta woreda, South Gondar zone, Northwest Ethiopia in 2019. METHODS: A community-based case-control study was conducted from March 25 to April 1, 2019. A structured questionnaire was used to collect data and for review of documents and discussion with livestock and health office staff. The collected data were analyzed by SPSS and presented in tables and graphs. RESULTS: A total of 20 human anthrax cases with an attack rate of 2.5 per 1000 population were reported from the affected kebele. The age of the cases ranged from 1 month to 65 years (median age = 37.5 years). Of the total cases, 66.7% were male and 77.8% were 15 and older. The probability of developing anthrax among people who had unvaccinated animals was higher than in those who didn't have unvaccinated animals with an AOR = 8.113 (95% CI 1.685-39.056) and the probability of getting anthrax in relation to people's awareness of anthrax was AOR = 0.114 (95% CI 0.025-0.524). CONCLUSION: An anthrax outbreak occurred in Wawa Mengera Kebele of Farta woreda. The presence of unvaccinated animals in a household was found to be a risk factor for anthrax cases. Timely animal vaccination and strengthening health education on the vaccination of animals, mode of transmission, and disposal of dead animals are essential for preventing anthrax cases.

Anthrax bio-surveillance of livestock in Arua District, Uganda, 2017-2018.

Anthrax, caused by Bacillus anthracis, is a widespread zoonotic disease with many human cases, especially in developing countries. Even with its global distribution, anthrax is a neglected disease with scarce information about its actual impact on the community level. Due to the ecological dynamics of anthrax transmission at the wildlife-livestock interface, the Sub-Saharan Africa region becomes a high-risk zone for maintaining and acquiring the disease. In this regard, some subregions of Uganda are endemic to anthrax with regular seasonal trends. However, there is scarce data about anthrax outbreaks in Uganda. Here, we confirmed the presence of B. anthracis in several livestock samples after a suspected anthrax outbreak among livestock and humans in Arua District. Additionally, we explored the potential risk factors of anthrax through a survey within the community kraals. We provide evidence that the most affected livestock species during the Arua outbreak were cattle (86%) compared to the rest of the livestock species present in the area. Moreover, the farmers' education level and the presence of people's anthrax cases were the most critical factors determining the disease's knowledge and awareness. Consequently, the lack of understanding of the ecology of anthrax may contribute to the spread of the infection between livestock and humans, and it is critical to reducing the presence and persistence of the B. anthracis spores in the environment. Finally, we discuss the increasingly recognized necessity to strengthen global capacity using a One Health approach to prevent, detect, control, and respond to public threats in Uganda.

The persistence of time: the lifespan of Bacillus anthracis spores in environmental reservoirs.

Anthrax is a lethal bacterial zoonosis primarily affecting herbivorous wildlife and livestock. Upon host death Bacillus anthracis vegetative cells form spores capable of surviving for years in soil. Anthrax transmission requires host exposure to large spore doses. Thus, conditions that facilitate higher spore concentrations or promote spore survival will increase the probability that a pathogen reservoir infects future hosts. We investigated abiotic and pathogen genomic variation in relation to spore concentrations in surface soils (0-1 cm depth) at 40 plains zebra (Equus quagga) anthrax carcass sites in Namibia. Specifically, how initial spore concentrations and spore survival were affected by seasonality associated with the timing of host mortality, local soil characteristics, and pathogen genomic variation. Zebras dying of anthrax in wet seasons-the peak season for anthrax in Etosha National Park-had soil spore concentrations 1.36 orders of magnitude higher than those that died in dry seasons. No other variables considered affected spore concentrations, and spore survival rates did not differ among sites. Surface soils at these pathogen reservoirs remained culture positive for a range of 3.8-10.4 years after host death. Future research could evaluate if seasonal patterns in spore concentrations are driven by differences in sporulation success or levels of terminal bacteremia.

Spatial analysis of human and livestock anthrax in Dien Bien province, Vietnam (2010-2019) and the significance of anthrax vaccination in livestock.

Anthrax is a serious zoonosis caused by Bacillus anthracis, which primarily affects wild herbivorous animals with spillover into humans. The disease occurs nearly worldwide but is poorly reported in Southeast Asian countries. In Vietnam, anthrax is underreported, and little is known about its temporal and spatial distributions. This paper examines the spatio-temporal distribution and epidemiological characteristics of human and livestock anthrax from Dien Bien province, Vietnam from 2010 to 2019. We also aim to define the role of livestock vaccination in reducing human cases. Historical anthrax data were collected by local human and animal health sectors in the province. Spatial rate smoothing and spatial clustering analysis, using Local Moran's I in GeoDa and space-time scan statistic in SaTScan, were employed to address these objectives. We found temporal and spatial overlap of anthrax incidence in humans and livestock with hotspots of human anthrax in the east. We identified three significant space-time clusters of human anthrax persisting from 2010 to 2014 in the east and southeast, each with high relative risk. Most of the human cases were male (69%), aged 15-59 years (80%), involved in processing, slaughtering, or eating meat of sick or dead livestock (96.9%) but environmental and unknown exposure were reported. Animal reports were limited compared to humans and at coarser spatial scale, but in areas with human case clusters. In years when livestock vaccination was high (>~25%), human incidence was reduced, with the opposite effect when vaccine rates dropped. This indicates livestock vaccination campaigns reduce anthrax burden in both humans and livestock in Vietnam, though livestock surveillance needs immediate improvement. These findings suggest further investigation and measures to strengthen the surveillance of human and animal anthrax for other provinces of Vietnam, as well as in other countries with similar disease context.

Anthrax hotspot mapping in Kenya support establishing a sustainable two-phase elimination program targeting less than 6% of the country landmass.

Using data collected from previous (n = 86) and prospective (n = 132) anthrax outbreaks, we enhanced prior ecological niche models (ENM) and added kernel density estimation (KDE) approaches to identify anthrax hotspots in Kenya. Local indicators of spatial autocorrelation (LISA) identified clusters of administrative wards with a relatively high or low anthrax reporting rate to determine areas of greatest outbreak intensity. Subsequently, we modeled the impact of vaccinating livestock in the identified hotspots as a national control measure. Anthrax suitable areas included high agriculture zones concentrated in the western, southwestern and central highland regions, consisting of 1043 of 1450 administrative wards, covering 18.5% country landmass, and hosting 30% of the approximately 13 million cattle population in the country. Of these, 79 wards covering 5.5% landmass and hosting 9% of the cattle population fell in identified anthrax hotspots. The rest of the 407 administrative wards covering 81.5% of the country landmass, were classified as low anthrax risk areas and consisted of the expansive low agricultural arid and semi-arid regions of the country that hosted 70% of the cattle population, reared under the nomadic pastoralism. Modelling targeted annual vaccination of 90% cattle population in hotspot administrative wards reduced > 23,000 human exposures. These findings support an economically viable first phase of anthrax control program in low-income countries where the disease is endemic, that is focused on enhanced animal and human surveillance in burden hotspots, followed by rapid response to outbreaks anchored on public education, detection and treatment of infected humans, and ring vaccination of livestock. Subsequently, the global anthrax elimination program focused on sustained vaccination and surveillance in livestock in the remaining few hotspots for a prolonged period (> 10 years) may be implemented.