1996-97 Global Anthrax Report

The second cutaneous anthrax infection diagnosed by metagenomic next-generation sequencing: A case report

RATIONALE

Anthrax is a severe zoonotic infectious disease caused by Bacillus anthracis. Most reported cases were traditionally diagnosed through culture and microscopy. We reported here the second case of cutaneous anthrax diagnosed by metagenomic next-generation sequencing (mNGS).

PATIENT CONCERNS

A 63-year-old man had a history of contact with an unwell sheep, developing local redness and swelling on wrist. The dorsal side of the left hand and forearm, with tension blisters on the back of the left.

DIAGNOSIS

B anthracis was detected from culturing and mNGS of tension blisters.

INTERVENTIONS

On the second day of admission, the patient was administered 3.2 million units of penicillin every 6 hours, and isolated and closely observed.

OUTCOMES

The patient improves and is discharged.

LESSONS

Traditional bacterial cultures are time-consuming, while mNGS offers the advantage of accurate, quick, high-throughput, unbiased sequencing of all genetic material in a sample, which is a good technical tool for assisting in the diagnosis of rare pathogen infections.

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.

Spatiotemporal Patterns of Anthrax, Vietnam, 1990–2015

Anthrax is a priority zoonosis for control in Vietnam. The geographic distribution of anthrax remains to be defined, challenging our ability to target areas for control. We analyzed human anthrax cases in Vietnam to obtain anthrax incidence at the national and provincial level. Nationally, the trendline for cases remained at ≈61 cases/year throughout the 26 years of available data, indicating control efforts are not effectively reducing disease burden over time. Most anthrax cases occurred in the Northern Midlands and Mountainous regions, and the provinces of Lai Chau, Dien Bien, Lao Cai, Ha Giang, Cao Bang, and Son La experienced some of the highest incidence rates. Based on spatial Bayes smoothed maps, every region of Vietnam experienced human anthrax cases during the study period. Clarifying the distribution of anthrax in Vietnam will enable us to better identify risk areas for improved surveillance, rapid clinical care, and livestock vaccination campaigns.

Characterization of Bacillus anthracis replication and persistence on environmental substrates associated with wildlife anthrax outbreaks

Anthrax is a zoonosis caused by the environmentally maintained, spore-forming bacterium Bacillus anthracis, affecting humans, livestock, and wildlife nearly worldwide. Bacterial spores are ingested, inhaled, and may be mechanically transmitted by biting insects or injection as occurs during heroin-associated human cases. Herbivorous hoofstock are very susceptible to anthrax. When these hosts die of anthrax, a localized infectious zone (LIZ) forms in the area surrounding the carcass as it is scavenged and decomposes, where viable populations of vegetative B. anthracis and spores contaminate the environment. In many settings, necrophagous flies contaminate the outer carcass, surrounding soils, and vegetation with viable pathogen while scavenging. Field observations in Texas have confirmed this process and identified primary browse species (e.g., persimmon) are contaminated. However, there are limited data available on B. anthracis survival on environmental substrates immediately following host death at a LIZ. Toward this, we simulated fly contamination by inoculating live-attenuated, fully virulent laboratory-adapted, and fully virulent wild B. anthracis strains on untreated leaves and rocks for 2, 5, and 7 days. At each time point after inoculation, the number of vegetative cells and spores were determined. Sporulation rates were extracted from these different time points to enable comparison of sporulation speeds between B. anthracis strains with different natural histories. We found all B. anthracis strains used in this study could multiply for 2 or more days post inoculation and persist on leaves and rocks for at least seven days with variation by strain. We found differences in sporulation rates between laboratory-adapted strains and wild isolates, with the live-attenuated strain sporulating fastest, followed by the wild isolates, then laboratory-adapted virulent strains. Extrapolating our wild strain lab results to potential contamination, a single blow fly may contaminate leaves with up to 8.62 x 105 spores per day and a single carcass may host thousands of flies. Replication outside of the carcass and rapid sporulation confirms the LIZ extends beyond the carcass for several days after formation and supports the necrophagous fly transmission pathway for amplifying cases during an outbreak. We note caution must be taken when extrapolating replication and sporulation rates from live-attenuated and laboratory-adapted strains of B. anthracis.

Epizootological and epidemiological situation of anthrax in Ukraine in the context of mandatory specific prevention in susceptible animals

The problem of zoonoses remains relevant in the context of reliable prevention of human disease and effective ways to achieve this result, in particular through the impact on susceptible animals by the efforts of veterinary medicine. Anthrax is an acute, particularly dangerous infectious disease of all species of farm, domestic and wild animals, as well as humans, which is caused by Bacillus anthracis microbes. The causative agent of anthrax belongs to the group of aerobic spore-forming bacteria and exists in two main forms: vegetative and spore. The vegetative form in the body of an infected animal can form a "capsule". In Ukraine, according to the provisions of the current "Instruction for the prevention and control of animal anthrax" (2000), the main method of preventing anthrax among animals is regular vaccination of animals susceptible to this disease. The authors conducted a retrospective analysis of the epizootic and epidemiological situation of anthrax in Ukraine for the period 1994–2021 and made a critical assessment of the performance of mandatory measures for specific prevention of susceptible animals. In order to find out the ecological and geographical features of the spread of anthrax, data on outbreaks of the disease in cattle, swine, small ruminants and humans on the territory of Ukraine were analyzed by regions for the time period under investigation. Over the past 28 years in Ukraine, animal anthrax was registered in in all areas except Zhytomyr region. In total, during the analyzed period, 177 affected points and 637 infected animals (cattle, small ruminants, pigs, horses, wild and fur-bearing animals, dogs) were registered (estimated at 3.59 animals per outbreak). Cattle were most often involved in the epizootic process, followed by pigs and small ruminants, while horses and other animal species were least infected. Ecological and geographical analysis showed that the largest number of affected points among animals during the analyzed period was found in Kyiv, Volyn, Kharkiv, Luhansk, Khmelnytskyi, Cherkasy, Odesa, and Vinnytsia regions. A small number of affected points during the analyzed period were found in Zakarpattia, Ternopil, Kherson, Autonomous Republic of Crimea, Poltava, Dnipropetrovsk and Ivano-Frankivsk regions. During the analyzed period, 68 people in 11 regions of Ukraine were infected with anthrax, 15 outbreaks were registered (4.46 people per outbreak). Most cases were reported in Donetsk, Kyiv and Odesa regions. The association between outbreaks of anthrax in animals and cases of anthrax among humans has been established, this dependency was 86.6% (the index of contiguity, which takes into account the number of years with simultaneous registration of animal and human cases, was 0.5). The authors thoroughly proved that it is vaccination among susceptible animals that will finally prevent the incidence of anthrax among people.

Anthrax outbreak amidst the COVID-19 pandemic in Africa: Challenges and possible solutions

Anthrax and coronavirus disease 2019 (COVID-19) are both notable zoonoses that have high morbidity and mortality, not to mention adverse socio-economic and health consequences on the communities they ravage. Anthrax wreaks disease amongst mammalian species worldwide and has an endemic distribution in Africa and Asia. Kenya, for example, records an average of 10 outbreaks annually. In 2014 and 2017, it held anthrax attack rates of 15% and 29%, respectively, and case fatality rates of 1–5%. As with COVID-19, effective surveillance, containment, and vaccination programs are crucial in the fight against anthrax. While there is no evidence of direct, human-to-human transmission of anthrax currently, Bacillus anthracis remains a disease of public health concern that serves to fuel the devastating effects of SARS-CoV-2 in African communities. In this commentary, we examine anthrax spread in Africa amidst COVID-19, the challenges faced by these simultaneous zoonoses, and the efforts put to combat both equally.

Anthrax Surveillance and the Limited Overlap Between Obligate Scavengers and Endemic Anthrax Zones in the United States

Anthrax is a zoonosis caused by the spore-forming bacterium Bacillus anthracis, with potential for high fatality rate, especially in herbivores. Upon host death, spores can enter the soil surrounding the carcass and be ingested by other animals feeding in the same location. Accordingly, surveillance to quickly identify and decontaminate anthrax carcasses is crucial to outbreak prevention. In endemic anthrax areas such as Texas and Africa, vultures are used as a surveillance tool for identifying presence and location of dead animals. However, many anthrax outbreaks in the United States have occurred in areas outside the ranges of both black and turkey vultures. Here, we used a longitudinal camera trap survey at carcass sites in southwestern Montana to investigate the utility of facultative avian scavengers on disease and carcass surveillance in a reemerging anthrax risk zone. From August 2016 to September 2018, camera traps at 11 carcass sites were triggered 1996 times by avian scavengers. While the majority were facultative avian scavengers such as corvids and eagles, our results suggest that facultative scavengers cannot replace vultures as a surveillance tool in this ecosystem due to their absence during the anthrax risk period (June to August), reduced search efficiency, or low flight patterns. We found that the conditions in Montana likely parallel systems elsewhere in the continental United States. Using ecological niche models of B. anthracis distribution overlaid with relative abundance maps of turkey vultures, we found that much of North Dakota, South Dakota, Minnesota, Wyoming, Nebraska, and Iowa have areas of anthrax risk, but low or absent turkey vulture populations. Without vultures in these areas, surveillance capacity is reduced, and it becomes more difficult to identify anthrax cases, meaning fewer carcasses are decontaminated, and consequently, outbreaks could become more frequent or severe.

Investigation on Anthrax in Bangladesh during the Outbreaks of 2011 and Definition of the Epidemiological Correlations

In 2011, in Bangladesh, 11 anthrax outbreaks occurred in six districts of the country. Different types of samples were collected from May to September in the six districts where anthrax had occurred in order to detect and type Bacillus anthracis (B. anthracis) strains. Anthrax was detected in 46.6% of the samples analysed, in particular in soils, but also in bone samples, water, animal feed, and rumen ingesta of dead animals. Canonical single nucleotide polymorphisms (CanSNPs) analysis showed that all the isolates belonged to the major lineage A, sublineage A.Br.001/002 of China and Southeast Asia while the multi-locus variable number of tandem repeats (VNTRs) analysis (MLVA) with 15 VNTRs demonstrated the presence of five genotypes, of which two resulted to be new genotypes. The single nucleotide repeats (SNRs) analysis showed 13 SNR types; nevertheless, due to its higher discriminatory power, the presence of two isolates with different SNR-type polymorphisms was detected within two MLVA genotypes. This study assumes that soil is not the only reason for the spread of the disease in Bangladesh; contaminated feed and water can also play an important role in the epidemiology of anthrax. Possible explanations for these epidemiological relationships are discussed.

Convergent evolution of diverse Bacillus anthracis outbreak strains toward altered surface oligosaccharides that modulate anthrax pathogenesis

Bacillus anthracis, a spore-forming gram-positive bacterium, causes anthrax. The external surface of the exosporium is coated with glycosylated proteins. The sugar additions are capped with the unique monosaccharide anthrose. The West African Group (WAG) B. anthracis have mutations rendering them anthrose deficient. Through genome sequencing, we identified 2 different large chromosomal deletions within the anthrose biosynthetic operon of B. anthracis strains from Chile and Poland. In silico analysis identified an anthrose-deficient strain in the anthrax outbreak among European heroin users. Anthrose-deficient strains are no longer restricted to West Africa so the role of anthrose in physiology and pathogenesis was investigated in B. anthracis Sterne. Loss of anthrose delayed spore germination and enhanced sporulation. Spores without anthrose were phagocytized at higher rates than spores with anthrose, indicating that anthrose may serve an antiphagocytic function on the spore surface. The anthrose mutant had half the LD50 and decreased time to death (TTD) of wild type and complement B. anthracis Sterne in the A/J mouse model. Following infection, anthrose mutant bacteria were more abundant in the spleen, indicating enhanced dissemination of Sterne anthrose mutant. At low sample sizes in the A/J mouse model, the mortality of ΔantC-infected mice challenged by intranasal or subcutaneous routes was 20% greater than wild type. Competitive index (CI) studies indicated that spores without anthrose disseminated to organs more extensively than a complemented mutant. Death process modeling using mouse mortality dynamics suggested that larger sample sizes would lead to significantly higher deaths in anthrose-negative infected animals. The model was tested by infecting Galleria mellonella with spores and confirmed the anthrose mutant was significantly more lethal. Vaccination studies in the A/J mouse model showed that the human vaccine protected against high-dose challenges of the nonencapsulated Sterne-based anthrose mutant. This work begins to identify the physiologic and pathogenic consequences of convergent anthrose mutations in B. anthracis.

Spatial Patterns of Anthrax Outbreaks and Cases among Livestock in Lesotho, 2005-2016

Background: Although anthrax occurs globally, the burden of the disease remains particularly high in Africa. Furthermore, the disease anthrax has significant public health and economic implications. However, sufficient attention has not been given to the geographic distribution of anthrax outbreaks and cases in Lesotho. Therefore, this study investigates the spatial patterns of anthrax outbreaks and cases among livestock in Lesotho from 2005 to 2016. Methods: A cross-sectional study design was adopted to realise the objectives of this study using retrospective data of anthrax outbreaks and cases recorded by the Department of Livestock Services (DLS) between 2005 and 2016. Anthrax outbreaks were geo-coded at village level and aggregated at district level. Proportions and 95% CI of anthrax outbreaks and cases by village and district were calculated. Cartographic maps displaying the distribution of anthrax outbreaks and cases at village and district level were constructed. Results: A total of 38 outbreaks were reported over the study period, and they were clustered in the Lowlands districts of Lesotho. Most outbreaks (52.6%, 20/38) in livestock were reported in the Maseru district. The Leribe district reported the lowest proportions of outbreaks (5.3%, 2/38) and cases (0.6%, 3/526). At the village level, 18% (7/38) of outbreaks were in Maseru Urban, followed by Ratau (16%, 6/38) and Mofoka (13%, 5/38). The Maseru district reported the highest (1.3%, 369/29,070) proportion of cases followed by Mafeteng (0.9%, 73/8530). The village with the most cases was Kolo (10.5%, 21/200), followed by Thaba-Chitja (7.7%, 33/430). Conclusion: Anthrax outbreaks and cases exclusively occur in the Lowlands districts of Lesotho, with villages such as Mahobong, Pitseng, Kolo, and Thaba-Chitja having a higher risk of anthrax disease. Findings of the present study have serious public health implications in light of the fact that between 2003 and 2008 Lesotho’s main abattoir was closed; hence, most of the meat in Lesotho was imported and/or sourced from the informal slaughter facilities. Much larger studies are needed to further investigate factors contributing to spatial disparities in anthrax outbreaks and cases observed in this study. Findings of the present study can be used to guide the formulation of a policy on prevention and control of anthrax in Lesotho.

Human anthrax in Kyrgyz Republic: Epidemiology and clinical features

BACKGROUND

Bacillus anthracis infects both humans and animals which leads to anthrax disease. The disease is still a global issue as it occurs naturally and has a potential use for bioterrorism/bio-weapons agents. This study aimed to investigate the clinical and epidemiologic features of human anthrax that has been seen in Kyrgyzstan.

METHODS

This study was carried out at the Osh Regional Hospital that is located in the southern regions of Kyrgyz Republic. Medical records of patient's diagnosed with cutaneous anthrax between 2005 and 2015 were reviewed. Epidemiology and clinical features of the infection and the effectiveness of antibiotic therapy were investigated.

RESULTS

Two hundred thirty four anthrax cases were reviewed. Among the patients, men in the 31-50 age group prevailed. Infection episodes that sought medical attention occurred mostly during the summer and autumn. Analysis of epidemiological data shows that anthrax contamination occurred as a result of direct contact with mainly farm animals, slaughtering, butchering and the selling of the meat. Cutaneous lesions were localized mostly in the upper extremities. Among the observed patients, a majority of the cases presented a mild form of the disease. The isolated strains of B. anthracis were mostly susceptible to amoxiclav, ofloxacin, 3rd generation of cephalosporins, doxycycline, ciprofloxacin, rifampicin, penicillin and streptomycin. A majority of the isolates were found to be resistant to ampicillin, gentamicin, chloramphenicol.

CONCLUSION

Anthrax is still an endemic disease that has lead to outbreaks in the Kyrgyz Republic. The transmission of human infection is seen by direct contact with ill animals or dead animal products. The common form seen in the clinical setting is cutaneous anthrax. Future studies should focus on the surveillance and infection control measurements associated with the anthrax.

Sporadic human cutaneous anthrax outbreak in Shaanxi Province, China: report of two cases from 2018

China’s compulsory annual livestock anthrax vaccination policy has remarkably reduced but not completely eradicated human anthrax infections. Herein we describe a sporadic human cutaneous anthrax outbreak involving two cases in 2018 in Shaanxi Province, both involving herdsman who dealt with unvaccinated and potentially sick cattle. Both patients showed Bacillus anthracis-positive blister smear and blood culture. Treatment with penicillin was followed by uneventful recovery for both. The prompt performance of the prophylactic measures successfully interrupted the further transmission of this sporadic human cutaneous anthrax outbreak.

Whole Genome Sequencing for Studying Bacillus anthracis from an Outbreak in the Abruzzo Region of Italy

Anthrax is a serious infectious disease caused by the gram-positive and spore-forming bacterium Bacillus anthracis. In Italy, anthrax is an endemic disease with sporadic cases each year and few outbreaks, especially in Southern Italy. However, new foci have been discovered in zones without previous history of anthrax. During summer 2016, an outbreak of anthrax caused the death of four goats in the Abruzzo region, where the disease had not been reported before. In order to investigate the outbreak, we sequenced one strain and compared it to 19 Italian B. anthracis genomes. Furthermore, we downloaded 71 whole genome sequences representing the global distribution of canonical SNP lineages and used them to verify the phylogenetic positioning. To this end, we analyzed and compared the genome sequences using canonical SNPs and the whole genome SNP-based analysis. Our results demonstrate that the outbreak strain belonged to the Trans-Eurasian (TEA) group A.Br.011/009, which is the predominant clade in Central-Southern Italy. In conclusion, the high genomic relatedness of the Italian TEA strains suggests their evolution from a common ancestor, while the spread is supposedly driven by trade as well as human and transhumance activities. Here, we demonstrated the capabilities of whole genome sequencing (WGS), which can be used as a tool for outbreak analyses and surveillance activities.

Nucleotide polymorphism assay for the identification of west African group Bacillus anthracis: a lineage lacking anthrose

Background

The exosporium of the anthrax-causing Bacillus anthracis endospores display a tetrasaccharide composed of three rhamnose residues and an unusual sugar termed anthrose. Anthrose is a proposed potential target for immunotherapy and for specific detection of B. anthracis. Although originally thought to be ubiquitous in B. anthracis, previous work identified an anthrose negative strain from a West African lineage isolated from cattle that could represent a vaccine escape mutant. These strains carry genes required for expression of the anthrose operon but premature stop codons resulting from an 8-bp insertion in BAS3320 (an amino-transferase) and a C/T substitution at position 892 of the BAS3321 (a glycosyltransferase) gene prevent anthrose expression. Various other single nucleotide polymorphisms (SNPs) have been identified throughout the operon and could be the basis for detection of anthrose-deficient strains.

Results

In this study, we evaluated rhAmp genotypic assays based on SNPs at positions 892 and 1352 of BAS3321 for detection and differentiation of anthrose negative (Ant⁻) West African strains. Discrimination of anthrose negative West African isolates was achieved with as low as 100 fg of DNA, whereas consistent genotyping of Sterne necessitated at least 1 pg of DNA.

Conclusions

Screening of a global panel of B. anthracis isolates showed anthrose-expressing alleles are prevalent worldwide whereas the anthrose-deficient phenotype is to date limited to West Africa. Our work also revealed a third, previously unreported anthrose genotype in which the operon is altogether missing from a Polish B. anthracis isolate.

Recurrent Anthrax Outbreaks in Humans, Livestock, and Wildlife in the Same Locality, Kenya, 2014-2017

Epidemiologic data indicate a global distribution of anthrax outbreaks associated with certain ecosystems that promote survival and viability of Bacillus anthracis spores. Here, we characterized three anthrax outbreaks involving humans, livestock, and wildlife that occurred in the same locality in Kenya between 2014 and 2017. Clinical and epidemiologic data on the outbreaks were collected using active case finding and review of human, livestock, and wildlife health records. Information on temporal and spatial distribution of prior outbreaks in the area was collected using participatory epidemiology. The 2014-2017 outbreaks in Nakuru West subcounty affected 15 of 71 people who had contact with infected cattle (attack rate = 21.1%), including seven with gastrointestinal, six with cutaneous, and two with oropharyngeal forms of the disease. Two (13.3%) gastrointestinal human anthrax cases died. No human cases were associated with infected wildlife. Of the 54 cattle owned in 11 households affected, 20 died (attack rate = 37%). The 2015 outbreak resulted in death of 10.5% of the affected herbivorous wildlife at Lake Nakuru National Park, including 745 of 4,500 African buffaloes (species-specific mortality rate = 17%) and three of 18 endangered white rhinos (species-specific mortality rate = 16%). The species mortality rate ranged from 1% to 5% for the other affected wildlife species. Participatory epidemiology identified prior outbreaks between 1973 and 2011 in the same area. The frequency and severity of outbreaks in this area suggests that it is an anthrax hotspot ideal for investigating risk factors associated with long-term survival of anthrax spores and outbreak occurrence.

Comparison of spatiotemporal patterns of historic natural Anthrax outbreaks in Minnesota and Kazakhstan

Disease spread in populations is a consequence of the interaction between host, pathogen, and environment, i.e. the epidemiological triad. Yet the influences of each triad component may vary dramatically for different settings. Comparison of environmental, demographic, socio-economic, and historical backgrounds may support tailoring site-specific control measures. Because of the long-term survival of Bacillus anthracis, Anthrax is a suitable example for studying the influence of triad components in different endemic settings. We compared the spatiotemporal patterns of historic animal Anthrax records in two endemic areas, located at northern latitudes in the western and eastern hemispheres. Our goal was to compare the spatiotemporal patterns in Anthrax progression, intensity, direction, and recurrence (disease hot spots), in relation to epidemiological factors and potential trigger events. Reported animal cases in Minnesota, USA (n = 289 cases between 1912 and 2014) and Kazakhstan (n = 3,997 cases between 1933 and 2014) were analyzed using the spatiotemporal directionality test and the spatial scan statistic. Over the last century Anthrax occurrence in Minnesota was sporadic whereas Kazakhstan experienced a long-term epidemic. Nevertheless, the seasonality was comparable between sites, with a peak in August. Declining number of cases at both sites was attributed to vaccination and control measures. The spatiotemporal directionality test detected a relative northeastern directionality in disease spread for long-term trends in Minnesota, whereas a southwestern directionality was observed in Kazakhstan. In terms of recurrence, the maximum timespans between cases at the same location were 55 and 60 years for Minnesota and Kazakhstan, respectively. Disease hotspots were recognized in both settings, with spatially overlapping clusters years apart. Distribution of the spatiotemporal cluster radii between study sites supported suggestion of site-specific control zones. Spatiotemporal patterns of Anthrax occurrence in both endemic regions were attributed to multiple potential trigger events including major river floods, changes in land use, agriculture, and susceptible livestock populations. Results here help to understand the long-term epidemiological dynamics of Anthrax while providing suggestions to the design and implementation of prevention and control programs, in endemic settings.

Spatio-temporal epidemiology of anthrax in Hippopotamus amphibious in Queen Elizabeth Protected Area, Uganda

BACKGROUND

Anthrax is a zoonotic disease primarily of herbivores, caused by Bacillus anthracis, a bacterium with diverse geographical and global distribution. Globally, livestock outbreaks have declined but in Africa significant outbreaks continue to occur with most countries still categorized as enzootic, hyper endemic or sporadic. Uganda experiences sporadic human and livestock cases. Severe large-scale outbreaks occur periodically in hippos (Hippopotamus amphibious) at Queen Elizabeth Protected Area, where in 2004/2005 and 2010 anthrax killed 437 hippos. Ecological drivers of these outbreaks and potential of hippos to maintain anthrax in the ecosystem remain unknown. This study aimed to describe spatio-temporal patterns of anthrax among hippos; examine significant trends associated with case distributions; and generate hypotheses for investigation of ecological drivers of anthrax.

METHODS

Spatio-temporal patterns of 317 hippo cases in 2004/5 and 137 in 2010 were analyzed. QGIS was used to examine case distributions; Spearman's nonparametric tests to determine correlations between cases and at-risk hippo populations; permutation models of the spatial scan statistics to examine spatio-temporal clustering of cases; directional tests to determine directionality in epidemic movements; and standard epidemic curves to determine patterns of epidemic propagation.

KEY FINDINGS

Results showed hippopotamus cases extensively distributed along water shorelines with strong positive correlations (p<0.01) between cases and at-risk populations. Significant (p<0.001) spatio-temporal clustering of cases occurred throughout the epidemics, pointing towards a defined source. Significant directional epidemic spread was detected along water flow gradient (206.6°) in 2004/5 and against flow gradient (20.4°) in 2010. Temporal distributions showed clustered pulsed epidemic waves.

CONCLUSION

These findings suggest mixed point-source propagated pattern of epidemic spread amongst hippos and points to likelihood of indirect spread of anthrax spores between hippos mediated by their social behaviour, forces of water flow, and persistent presence of infectious carcasses amidst schools. This information sheds light on the epidemiology of anthrax in highly social wildlife, can help drive insight into disease control, wildlife conservation, and tourism management, but highlights the need for analytical and longitudinal studies aimed at clarifying the hypotheses.

An Optimal Control Model to Reduce and Eradicate Anthrax Disease in Herbivorous Animals

Anthrax is a fatal infectious disease which can affect animals and humans alike. Anthrax outbreaks occur periodically in animals, and they are of particular concern in herbivores, due to substantial economic consequences associated with animal death. The purpose of this study is to develop optimal control interventions that focus on vaccinating susceptible animals and/or removing infected carcasses. Our mathematical goal is to minimize the infectious animal population while reducing the cost of interventions. Optimal control interventions are derived theoretically, and numerical results with conclusions are presented.

Temporal patterns of anthrax outbreaks among livestock in Lesotho, 2005-2016

Background

Although anthrax is endemic in Lesotho, limited information is available on the patterns of the disease among livestock animals. This study investigated temporal patterns of anthrax outbreaks and cases among livestock animals in Lesotho.

Methods

Secondary data of anthrax outbreaks reported to the Department of Livestock Services between January 2005 and December 2016 was used for this study. Proportions of anthrax outbreaks and cases, and their corresponding 95% confidence interval were calculated and compared across year, season, month and region using the Chi-square or Fisher’s exact test. The autoregression model was used to evaluate annual trends of anthrax outbreaks and cases.

Results

A total of 38 outbreaks were reported in the Lowlands districts of Lesotho. District was significantly (p<0.0001) associated with outbreaks and cases, with the highest proportions of outbreaks (52.6%) and cases (70.2%) reported in Maseru. Significantly (p = 0.0004) higher proportions of anthrax outbreaks (78.9%) and cases (95.1%) were reported in the rainy-hot season compared to the dry-cold season. Five hundred and twenty-six (n = 526) anthrax cases were reported with significantly (p<0.0001) higher proportion of cases (70.3%) in cattle compared to other species. Higher proportion of anthrax cases (35.9%) were reported in 2008 and during the months of February (30.8%) and April (30.2%). There was no significant annual trend in anthrax outbreaks (r = 0.0282; p = 0.6213) and cases (r = 0.0873; p = 0.3512) over the study period.

Conclusion

The burden of anthrax in Lesotho is significantly higher in cattle. Anthrax outbreaks occur only in the lowland districts and follow a seasonal pattern. Therefore, more effort should be targeted at curbing the disease in cattle and the lowlands districts. Furthermore, there should be heightened monitoring of cases in the rainy season to ensure that resultant carcasses are disposed of appropriately to minimise future outbreaks.

Epidemiology of Human Anthrax in China, 1955-2014

Using national surveillance data for 120,111 human anthrax cases recorded during 1955−2014, we analyzed the temporal, seasonal, geographic, and demographic distribution of this disease in China. After 1978, incidence decreased until 2013, when it reached a low of 0.014 cases/100,000 population. The case-fatality rate, cumulatively 3.6% during the study period, has also decreased since 1990. Cases occurred throughout the year, peaking in August. Geographic distribution decreased overall from west to east, but the cumulative number of affected counties increased during 2005−2014. The disease has shifted from industrial to agricultural workers; 86.7% of cases occurred in farmers and herdsmen. Most (97.7%) reported cases were the cutaneous form. Although progress has been made in reducing incidence, this study highlights areas that need improvement. Adequate laboratory diagnosis is lacking; only 7.6% of cases received laboratory confirmation. Geographic expansion of the disease indicates that livestock control programs will be essential in eradicating anthrax.

Modeling the environmental suitability of anthrax in Ghana and estimating populations at risk: Implications for vaccination and control

Anthrax is hyper-endemic in West Africa. Despite the effectiveness of livestock vaccines in controlling anthrax, underreporting, logistics, and limited resources makes implementing vaccination campaigns difficult. To better understand the geographic limits of anthrax, elucidate environmental factors related to its occurrence, and identify human and livestock populations at risk, we developed predictive models of the environmental suitability of anthrax in Ghana. We obtained data on the location and date of livestock anthrax from veterinary and outbreak response records in Ghana during 2005–2016, as well as livestock vaccination registers and population estimates of characteristically high-risk groups. To predict the environmental suitability of anthrax, we used an ensemble of random forest (RF) models built using a combination of climatic and environmental factors. From 2005 through the first six months of 2016, there were 67 anthrax outbreaks (851 cases) in livestock; outbreaks showed a seasonal peak during February through April and primarily involved cattle. There was a median of 19,709 vaccine doses [range: 0–175 thousand] administered annually. Results from the RF model suggest a marked ecological divide separating the broad areas of environmental suitability in northern Ghana from the southern part of the country. Increasing alkaline soil pH was associated with a higher probability of anthrax occurrence. We estimated 2.2 (95% CI: 2.0, 2.5) million livestock and 805 (95% CI: 519, 890) thousand low income rural livestock keepers were located in anthrax risk areas. Based on our estimates, the current anthrax vaccination efforts in Ghana cover a fraction of the livestock potentially at risk, thus control efforts should be focused on improving vaccine coverage among high risk groups.

Anthrax is a soil-borne zoonotic disease found worldwide. In the West African nation of Ghana, anthrax outbreaks occur annually with a high burden to livestock keepers and their animals. To control anthrax in both humans and animals, annual livestock vaccination is recommended in endemic regions. However, in resource poor areas distributing and administering vaccine is difficult, in part, due to underreporting, logistical issues, limited resources, and an under appreciation of the geographic extent of anthrax risk zones. Our objective was to model high spatial resolution anthrax outbreak data, collected in Ghana, using a machine learning algorithm (random forest). To achieve this, we used a combination of climatic and environmental characteristics to predict the potential environmental suitability of anthrax, map its distribution, and identify livestock and human populations at risk. Results indicate a marked ecological divide separating the broad areas of environmental suitability in northern Ghana from the southern part of the country, which closely mirrors the ecotone transitions from southern tropical and deciduous forests to the northern Sudanian and Guinea Savanna. Based on our model prediction, we estimated >3 million combined ruminant livestock and low income livestock keepers are situated in anthrax risk zones. These findings suggest a low level of annual livestock vaccination coverage among high risk groups. Thus, integrating control strategies from both the veterinary and human health sectors are needed to improve surveillance and increase vaccine dissemination and adoption by rural livestock keepers in Ghana and the surrounding region.

Changing livestock vaccination policy alters the epidemiology of human anthrax, Georgia, 2000-2013

Anthrax is a widely spread zoonotic disease found on nearly every continent. To control the disease in humans and animals, annual livestock vaccination is recommended. However, in 2007, the country of Georgia ended its policy of compulsory annual livestock anthrax vaccination. Our objective was to assess how the epidemiology of human anthrax has evolved from 2000-2013 in Georgia, in the wake of this cessation. We used passive surveillance data on epidemiological surveys of human anthrax case patients. Risk factors and rates of self-reported sources of infection were compared, before and after the change in livestock vaccination policy. We mapped ethnicity-adjusted incidence during the two periods and assessed changes in the spatial pattern of risk. The overall risk of human anthrax increased >5-fold, from 0.7 cases per 100,000 in 2000 to 3.7 cases per 100,000 by 2013. Ethnic disparities in risk became pronounced; from 2000 to 2013, incidence increased >60-fold in Azerbaijanis from 0.35 to 21.1 cases/100,000 Azerbaijanis compared to 0.61 to 1.9 cases/100,000 among ethnic Georgians. Food-borne exposures from purchasing meat increased from 11% in 2000-2006 to 21% in 2007-2013. Spatial analyses revealed a shift from a random pattern of reporting pre-policy change to clustering among district municipalities following the change in policy. Our findings indicate there were unintended human health consequences associated with changing livestock vaccination policy. Following a reduction in the immunizations administered, there was a major shift in the epidemiology of human anthrax in Georgia. Current infection risk is now highest among ethnic minorities. Increased reporting among individuals uncharacteristically at risk for anthrax from foodborne exposures suggests spillover from modes of agricultural production. Given the importance of human-livestock health linkages, careful evaluations of policy need to be undertaken before changes to animal vaccination are made.

Modeling the Ecological Niche of Bacillus anthracis to Map Anthrax Risk in Kyrgyzstan

Anthrax, caused by the environmental bacterium Bacillus anthracis, is an important zoonosis nearly worldwide. In Central Asia, anthrax represents a major veterinary and public health concern. In the Republic of Kyrgyzstan, ongoing anthrax outbreaks have been reported in humans associated with handling infected livestock and contaminated animal by-products such as meat or hides. The current anthrax situation has prompted calls for improved insights into the epidemiology, ecology, and spatial distribution of the disease in Kyrgyzstan to better inform control and surveillance. Disease control for both humans and livestock relies on annual livestock vaccination ahead of outbreaks. Toward this, we used a historic database of livestock anthrax reported from 1932 to 2006 mapped at high resolution to develop an ecological niche model-based prediction of B. anthracis across Kyrgyzstan and identified spatial clusters of livestock anthrax using a cluster morphology statistic. We also defined the seasonality of outbreaks in livestock. Cattle were the most frequently reported across the time period, with the greatest number of cases in late summer months. Our niche models defined four areas as suitable to support pathogen persistence, the plateaus near Talas and Bishkek, the valleys of western Kyrgyzstan along the Fergana Valley, and the low-lying areas along the shore of Lake Isyk-Kul. These areas should be considered "at risk" for livestock anthrax and subsequent human cases. Areas defined by the niche models can be used to prioritize anthrax surveillance and inform efforts to target livestock vaccination campaigns.

Alternative pre-approved and novel therapies for the treatment of anthrax

BACKGROUND

Bacillus anthracis, the causative agent of anthrax, is a spore forming and toxin producing rod-shaped bacterium that is classified as a category A bioterror agent. This pathogenic microbe can be transmitted to both animals and humans. Clinical presentation depends on the route of entry (direct contact, ingestion, injection or aerosolization) with symptoms ranging from isolated skin infections to more severe manifestations such as cardiac or pulmonary shock, meningitis, and death. To date, anthrax is treatable if antibiotics are administered promptly and continued for 60 days. However, if treatment is delayed or administered improperly, the patient's chances of survival are decreased drastically. In addition, antibiotics are ineffective against the harmful anthrax toxins and spores. Therefore, alternative therapeutics are essential. In this review article, we explore and discuss advances that have been made in anthrax therapy with a primary focus on alternative pre-approved and novel antibiotics as well as anti-toxin therapies.

METHODS

A literature search was conducted using the University of Manitoba search engine. Using this search engine allowed access to a greater variety of journals/articles that would have otherwise been restricted for general use. In order to be considered for discussion for this review, all articles must have been published later than 2009.

RESULTS

The alternative pre-approved antibiotics demonstrated high efficacy against B. anthracis both in vitro and in vivo. In addition, the safety profile and clinical pharmacology of these drugs were already known. Compounds that targeted underexploited bacterial processes (DNA replication, RNA synthesis, and cell division) were also very effective in combatting B. anthracis. In addition, these novel compounds prevented bacterial resistance. Targeting B. anthracis virulence, more specifically the anthrax toxins, increased the length of which treatment could be administered.

CONCLUSIONS

Several novel and pre-existing antibiotics, as well as toxin inhibitors, have shown increasing promise. A combination treatment that targets both bacterial growth and toxin production would be ideal and probably necessary for effectively combatting this armed bacterium.

Serum paraoxonase activity and oxidative stress levels in patients with cutaneous anthrax

INTRODUCTION

Anthrax is a bacterial disease caused by the aerobic sporeforming bacterium Bacillus anthracis. It has been suggested that oxidative stress plays an important role in the pathogenesis of B. anthracis. The aim of this study was to investigate serum paraoxonase 1 (PON1) activity, catalase activity, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) levels in patients with cutaneous anthrax.

MATERIALS AND METHODS

Fifteen patients with cutaneous anthrax and 15 healthy controls were enrolled in this study. The serum MDA levels, SOD levels, paraoxonase, arylesterase, and catalase activities were measured using a spectrophotometer.

RESULTS

The serum SOD levels, paraoxonase, arylesterase, and catalase activities were significantly lower in patients with cutaneous anthrax than in controls (for all, p < 0.001), whereas MDA levels were significantly higher ( p < 0.001). No significant correlation was found between serum paraoxonase activity, arylesterase activity, SOD levels, and MDA levels (all, p > 0.05) in patients with cutaneous anthrax.

CONCLUSIONS

The current study was the first to show decreased antioxidant levels and increased oxidant levels in patients with cutaneous anthrax. Therefore, decreased PON1 activity may play a role in the pathogenesis of cutaneous anthrax.

Applying Science: Opportunities to Inform Disease Management Policy with Cooperative Research within a One Health Framework

The ongoing Ebola outbreak in West Africa and the current saiga antelope die off in Kazakhstan each represent very real and difficult to manage public or veterinary health crises. They also illustrate the importance of stable and funded surveillance and sound policy for intervention or disease control. While these two events highlight extreme cases of infectious disease (Ebola) or (possible) environmental exposure (saiga), diseases such as anthrax, brucellosis, tularemia, and plague are all zoonoses that pose risks and present surveillance challenges at the wildlife-livestock-human interfaces. These four diseases are also considered important actors in the threat of biological terror activities and have a long history as legacy biowarfare pathogens. This paper reviews recent studies done cooperatively between American and institutions within nations of the Former Soviet Union (FSU) focused on spatiotemporal, epidemiological, and ecological patterns of these four zoonoses. We examine recent studies and discuss the possible ways in which techniques, including ecological niche modeling, disease risk modeling, and spatiotemporal cluster analysis, can inform disease surveillance, control efforts, and impact policy. Our focus is to posit ways to apply science to disease management policy and actual management or mitigation practices. Across these examples, we illustrate the value of cooperative studies that bring together modern geospatial and epidemiological analyses to improve our understanding of the distribution of pathogens and diseases in livestock, wildlife, and humans. For example, ecological niche modeling can provide national level maps of pathogen distributions for surveillance planning, while space-time models can identify the timing and location of significant outbreak events for defining active control strategies. We advocate for the need to bring the results and the researchers from cooperative studies into the meeting rooms where policy is negotiated and use these results to inform future disease surveillance and control or eradication campaigns.

The necrophagous fly anthrax transmission pathway: empirical and genetic evidence from wildlife epizootics

Early studies confirmed Bacillus anthracis in emesis and feces of flies under laboratory conditions, but there is little empirical field evidence supporting the roles of flies in anthrax transmission. We collected samples during outbreaks of anthrax affecting livestock and native and exotic wildlife on two ranches in West Texas (2009-2010). Sampling included animal carcasses, maggots, adult flies feeding on or within several meters of carcasses, and leaves from surrounding vegetation. Microbiology and PCR were used to detect B. anthracis in the samples. Viable B. anthracis and/or PCR-positive results were obtained from all represented sample types. Genetic analysis of B. anthracis samples using multilocus variable number tandem repeat analysis (MLVA) confirmed that each ranch represented a distinct genetic lineage. Within each ranch, we detected the same genotype of B. anthracis from carcasses, maggots, and adult flies. The results of this study provide evidence supporting a transmission cycle in which blowflies contaminate vegetation near carcasses that may then infect additional browsing animals during anthrax outbreaks in the shrubland environment of West Texas.

Human Brucellosis Trends: Re-emergence and Prospects for Control Using a One Health Approach in Azerbaijan (1983-2009)

Brucellosis is one of the most common and widely spread zoonotic diseases in the world. Control of the disease in humans is dependent upon limiting the infection in animals through surveillance and vaccination. Given the dramatic economic and political changes that have taken place in the former Soviet Union, which have limited control, evaluating the status of human brucellosis in former Soviet states is crucial. We assessed annual spatial and temporal trends in the epidemiology of human brucellosis in Azerbaijan, 1983-2009, in conjunction with data from a livestock surveillance and control programme (2002-2009). To analyse trends, we used a combination of segmented regression and spatial analysis. From 1983 to 2009, a total of 11 233 cases of human brucellosis were reported. Up to the mid-1990s, the incidence of human brucellosis showed a pattern of re-emergence, increasing by 25% annually, on average. Following Soviet governance, the incidence rates peaked, increasing by 1.8% annually, on average, and subsequently decreasing by 5% annually, on average, during the period 2002-2009. Despite recent national declines in human incidence, we identified geographic changes in the case distribution characterized by a geographic expansion and an increasing incidence among districts clustered in the south-east, compared to a decrease of elsewhere in the country. Males were consistently, disproportionately afflicted (71%) and incidence was highest in the 15 to 19 age group (18.1 cases/100 000). During the period 2002-2009, >10 million small ruminants were vaccinated with Rev1. Our findings highlight the improving prospects for human brucellosis control following livestock vaccination; however, the disease appears to be re-emerging in south-eastern Azerbaijan. Sustained one health measures are needed to address changing patterns of brucellosis in Azerbaijan and elsewhere in the former Soviet Union.

Whole Genome-Sequencing and Phylogenetic Analysis of a Historical Collection of Bacillus anthracis Strains from Danish Cattle

Bacillus anthracis, the causative agent of anthrax, is known as one of the most genetically monomorphic species. Canonical single-nucleotide polymorphism (SNP) typing and whole-genome sequencing were used to investigate the molecular diversity of eleven B. anthracis strains isolated from cattle in Denmark between 1935 and 1988. Danish strains were assigned into five canSNP groups or lineages, i.e. A.Br.001/002 (n = 4), A.Br.Ames (n = 2), A.Br.008/011 (n = 2), A.Br.005/006 (n = 2) and A.Br.Aust94 (n = 1). The match with the A.Br.Ames lineage is of particular interest as the occurrence of such lineage in Europe is demonstrated for the first time, filling an historical gap within the phylogeography of the lineage. Comparative genome analyses of these strains with 41 isolates from other parts of the world revealed that the two Danish A.Br.008/011 strains were related to the heroin-associated strains responsible for outbreaks of injection anthrax in drug users in Europe. Eight novel diagnostic SNPs that specifically discriminate the different sub-groups of Danish strains were identified and developed into PCR-based genotyping assays.

Bacillus anthracis Diversity and Geographic Potential across Nigeria, Cameroon and Chad: Further Support of a Novel West African Lineage

Zoonoses, diseases affecting both humans and animals, can exert tremendous pressures on human and veterinary health systems, particularly in resource limited countries. Anthrax is one such zoonosis of concern and is a disease requiring greater public health attention in Nigeria. Here we describe the genetic diversity of Bacillus anthracis in Nigeria and compare it to Chad, Cameroon and a broader global dataset based on the multiple locus variable number tandem repeat (MLVA-25) genetic typing system. Nigerian B. anthracis isolates had identical MLVA genotypes and could only be resolved by measuring highly mutable single nucleotide repeats (SNRs). The Nigerian MLVA genotype was identical or highly genetically similar to those in the neighboring countries, confirming the strains belong to this unique West African lineage. Interestingly, sequence data from a Nigerian isolate shares the anthrose deficient genotypes previously described for strains in this region, which may be associated with vaccine evasion. Strains in this study were isolated over six decades, indicating a high level of temporal strain stability regionally. Ecological niche models were used to predict the geographic distribution of the pathogen for all three countries. We describe a west-east habitat corridor through northern Nigeria extending into Chad and Cameroon. Ecological niche models and genetic results show B. anthracis to be ecologically established in Nigeria. These findings expand our understanding of the global B. anthracis population structure and can guide regional anthrax surveillance and control planning.

Anthrax, caused by the soil-borne bacterium Bacillus anthracis, is a disease with important public health and national security implications globally. Understanding the global genetic diversity of the pathogen is important for epidemiological and forensic investigations of anthrax events. Toward this, we describe B. anthracis genetic diversity in Nigeria and confirm it belongs to a unique West African genetic group not yet reported beyond neighboring Cameroon and Chad and Mali. This refines the global phylogeny of B. anthracis, allowing the development of more accurate diagnostics. We coupled these efforts with ecological niche modeling to map the geographic distribution of this strain group across the region. Suitable habitat for the pathogen is predicted across central Nigeria from west to east into Cameroon and Chad. Understanding the geography of B. anthracis plays an important role in informing public health by targeting disease control to high risk regions. This is particularly important in resource limited areas where intervention strategies are constrained and zoonotic disease risk is high.

Microevolution of Anthrax from a Young Ancestor (M.A.Y.A.) Suggests a Soil-Borne Life Cycle of Bacillus anthracis

During an anthrax outbreak at the Pollino National Park (Basilicata, Italy) in 2004, diseased cattle were buried and from these anthrax-foci Bacillus anthracis endospores still diffuse to the surface resulting in local accumulations. Recent data suggest that B. anthracis multiplies in soil outside the animal-host body. This notion is supported by the frequent isolation of B. anthracis from soil lacking one or both virulence plasmids. Such strains represent an evolutionary dead end, as they are likely no longer able to successfully infect new hosts. This loss of virulence plasmids is explained most simply by postulating a soil-borne life cycle of the pathogen. To test this hypothesis we investigated possible microevolution at two natural anthrax foci from the 2004 outbreak. If valid, then genotypes of strains isolated from near the surface at these foci should be on a different evolutionary trajectory from those below residing in deeper-laying horizons close to the carcass. Thus, the genetic diversity of B. anthracis isolates was compared conducting Progressive Hierarchical Resolving Assays using Nucleic Acids (PHRANA) and next generation Whole Genome Sequencing (WGS). PHRANA was not discriminatory enough to resolve the fine genetic relationships between the isolates. Conversely, WGS of nine isolates from near-surface and nine from near-carcass revealed five isolate specific SNPs, four of which were found only in different near-surface isolates. In support of our hypothesis, one surface-isolate lacked plasmid pXO1 and also harbored one of the unique SNPs. Taken together, our results suggest a limited soil-borne life cycle of B. anthracis.

Human anthrax outbreak associated with livestock exposure: Georgia, 2012

Human anthrax cases reported in the country of Georgia increased 75% from 2011 (n = 81) to 2012 (n = 142). This increase prompted a case-control investigation using 67 culture- or PCR-confirmed cases and 134 controls matched by residence and gender to investigate risk factor(s) for infection during the month before case onset. Independent predictors most strongly associated with disease in the multivariable modelling were slaughtering animals [odds ratio (OR) 7·3, 95% confidence interval (CI) 2·9-18·1, P 1 km; 15 (12%) of 125 had sick livestock; and 11 (9%) of 128 respondents reported finding dead livestock. We recommend joint public health and veterinary anthrax case investigations to identify areas of increased risk for livestock anthrax outbreaks, annual anthrax vaccination of livestock in those areas, and public awareness education.

Single-nucleotide polymorphism discrimination using high-resolution melting analysis for the genotyping of Bacillus anthracis

High-resolution melting (HRM) is a post-PCR technique that determines with high precision the melt profile of PCR products using a new generation of double-stranded DNA-binding dyes and accurate fluorescence data acquisition over small temperature increments. The method can be used to interrogate small sets of single-nucleotide polymorphisms (SNPs). Here, we describe a simple and cost-effective HRM-based method for the screening of 14 phylogenetically informative SNPs within the genome of Bacillus anthracis that subtype the species into 13 major sublineages or subgroups. Fourteen monoplex and seven duplex SNP-discrimination assays have been designed. We detail the parameters most important for the successful application of HRM for B. anthracis genotyping.

Fate of Bacillus anthracis during production of laboratory-scale cream cheese and homemade-style yoghurt

The viability of Bacillus anthracis during production and storage of cream cheese and yoghurt was evaluated. Experimental cheeses were manufactured from whole milk inoculated with a suspension of B. anthracis vegetative cells and spores at a final concentration of 10(4) cfu/ml. Lactic acid bacteria (LAB) and lab ferment were used to induce milk ripening and milk coagulation. The pH-value of the contaminated milk dropped below 4.5 within the first 6 h and the amount of LAB increased by approximately 2-logs. During cheese production and storage at 5-9 °C for 24 days no growth of B. anthracis was observed. The amount of vegetative cells and spores fluctuated by 1-log. Inoculation of whole milk with heat-treated spores at 10(4) cfu/ml resulted in a slight increase of vegetative cell counts during the first 6 h. This indicated that germination occurred, but replication of vegetative cells was still inhibited in the produced cheese. Incubation of cheeses at room temperature or heating after milk coagulation strongly reduced the amount of LAB but had no effect on the growth behaviour of B. anthracis. The vegetative cell and spore content remained steady at 10(4) cfu/100 mg. During yoghurt production the pH-value decreased within 5 h below 5 and growth of B. anthracis was inhibited throughout storage. A pH-value of 5 or less is likely a critical factor to control the growth of B. anthracis. However, spores remained viable in experimental cream cheeses and yoghurts and are a potential risk of infection.

Gastrointestinal helminths may affect host susceptibility to anthrax through seasonal immune trade-offs

Background

Most vertebrates experience coinfections, and many pathogen-pathogen interactions occur indirectly through the host immune system. These interactions are particularly strong in mixed micro-macroparasite infections because of immunomodulatory effects of helminth parasites. While these trade-offs have been examined extensively in laboratory animals, few studies have examined them in natural systems. Additionally, many wildlife pathogens fluctuate seasonally, at least partly due to seasonal host immune changes. We therefore examined seasonality of immune resource allocation, pathogen abundance and exposure, and interactions between infections and immunity in plains zebra (Equus quagga) in Etosha National Park (ENP), Namibia, a system with strongly seasonal patterns of gastrointestinal (GI) helminth infection intensity and concurrent anthrax outbreaks. Both pathogens are environmentally transmitted, and helminth seasonality is driven by environmental pressures on free living life stages. The reasons behind anthrax seasonality are currently not understood, though anthrax is less likely directly driven by environmental factors.

Results

We measured a complex, interacting set of variables and found evidence that GI helminth infection intensities, eosinophil counts, IgE and IgGb antibody titers, and possibly IL-4 cytokine signaling were increased in wetter seasons, and that ectoparasite infestations and possibly IFN-γ cytokine signaling were increased in drier seasons. Monocyte counts and anti-anthrax antibody titers were negatively associated with wet season eosinophilia, and monocytes were negatively correlated with IgGb and IgE titers. Taken together, this supports the hypothesis that ENP wet seasons are characterized by immune resource allocation toward Th-2 type responses, while Th1-type immunity may prevail in drier seasons, and that hosts may experience Th1-Th2 trade-offs. We found evidence that this Th2-type resource allocation is likely driven by GI parasite infections, and that these trade-offs may render hosts less capable of concurrently mounting effective Th1-type immune responses against anthrax.

Conclusions

This study is one of the first to examine laboratory-demonstrated Th1-Th2 trade-offs in a natural system. It provides evidence that seasonally bound pathogens may affect, through immunology, transmission dynamics of pathogens that might otherwise not be seasonally distributed. It suggests that, by manipulating the internal host ecosystem, GI parasites may influence the external ecosystem by affecting the dynamics of another environmentally transmitted pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/s12898-014-0027-3) contains supplementary material, which is available to authorized users.

Human cutaneous anthrax, Georgia 2010-2012

We assessed the occurrence of human cutaneous anthrax in Georgia during 2010--2012 by examining demographic and spatial characteristics of reported cases. Reporting increased substantially, as did clustering of cases near urban centers. Control efforts, including education about anthrax and livestock vaccination, can be directed at areas of high risk.

Genetic diversity of Bacillus anthracis in Europe: genotyping methods in forensic and epidemiologic investigations

Bacillus anthracis, the etiological agent of anthrax, a zoonosis relatively common throughout the world, can be used as an agent of bioterrorism. In naturally occurring outbreaks and in criminal release of this pathogen, a fast and accurate diagnosis is crucial to an effective response. Microbiological forensics and epidemiologic investigations increasingly rely on molecular markers, such as polymorphisms in DNA sequence, to obtain reliable information regarding the identification or source of a suspicious strain. Over the past decade, significant research efforts have been undertaken to develop genotyping methods with increased power to differentiate B. anthracis strains. A growing number of DNA signatures have been identified and used to survey B. anthracis diversity in nature, leading to rapid advances in our understanding of the global population of this pathogen. This article provides an overview of the different phylogenetic subgroups distributed across the world, with a particular focus on Europe. Updated information on the anthrax situation in Europe is reported. A brief description of some of the work in progress in the work package 5.1 of the AniBioThreat project is also presented, including (1) the development of a robust typing tool based on a suspension array technology and multiplexed single nucleotide polymorphisms scoring and (2) the typing of a collection of DNA from European isolates exchanged between the partners of the project. The know-how acquired will contribute to improving the EU's ability to react rapidly when the identity and real origin of a strain need to be established.

Serum adenosine deaminase activity in cutaneous anthrax

BACKGROUND

Adenosine deaminase (ADA) activity has been discovered in several inflammatory conditions; however, there are no data associated with cutaneous anthrax. The aim of this study was to investigate serum ADA activity in patients with cutaneous anthrax.

MATERIAL AND METHODS

Sixteen patients with cutaneous anthrax and 17 healthy controls were enrolled. We measured ADA activity; peripheral blood leukocyte, lymphocyte, neutrophil, and monocyte counts; erythrocyte sedimentation rate; and C reactive protein levels.

RESULTS

Serum ADA activity was significantly higher in patients with cutaneous anthrax than in the controls (p<0.001). A positive correlation was observed between ADA activity and lymphocyte counts (r=0.589, p=0.021) in the patient group.

CONCLUSIONS

This study suggests that serum ADA could be used as a biochemical marker in cutaneous anthrax.

Changing patterns of human anthrax in Azerbaijan during the post-Soviet and preemptive livestock vaccination eras

We assessed spatial and temporal changes in the occurrence of human anthrax in Azerbaijan during 1984 through 2010. Data on livestock outbreaks, vaccination efforts, and human anthrax incidence during Soviet governance, post-Soviet governance, preemptive livestock vaccination were analyzed. To evaluate changes in the spatio-temporal distribution of anthrax, we used a combination of spatial analysis, cluster detection, and weighted least squares segmented regression. Results indicated an annual percent change in incidence of (+)11.95% from 1984 to 1995 followed by declining rate of -35.24% after the initiation of livestock vaccination in 1996. Our findings also revealed geographic variation in the spatial distribution of reporting; cases were primarily concentrated in the west early in the study period and shifted eastward as time progressed. Over twenty years after the dissolution of the Soviet Union, the distribution of human anthrax in Azerbaijan has undergone marked changes. Despite decreases in the incidence of human anthrax, continued control measures in livestock are needed to mitigate its occurrence. The shifting patterns of human anthrax highlight the need for an integrated "One Health" approach that takes into account the changing geographic distribution of the disease.

Asymmetric dimethylarginine levels in patients with cutaneous anthrax: a laboratory analysis

BACKGROUND

Asymmetric dimethylarginine (ADMA), the main endogenous inhibitor of nitric oxide synthase, is considered to be associated with endothelial dysfunction. High ADMA levels have been shown to be related with disorders causing vascular inflammation such as hypertension, hypercholesterolemia, atherosclerosis, chronic heart failure, stroke and sepsis. Cutaneous anthrax (CA) is a serious infectious disease which may cause vasculitis. The aim of the study was to investigate the serum ADMA levels in patients with CA.

METHODS

A total of 35 serum samples of the patients with CA and 18 control sera were tested for ADMA levels using ADMA ELISA kit (Immunodiagnostik AG, Bensheim, Germany).

RESULTS

ADMA levels were found to be significantly higher in the patients group than the controls (p < 0.001). In addition, ADMA levels were found to be positively associated with sedimentation rates (R = 0.413; p = 0.026), and inversely associated with international normalized ratio (INR) levels (R = -0.46; p = 0.011). A cut-off value of 0.475 of ADMA had a sensitivity of 74.3%, specificity of 77.8%, and accuracy of 75.5% in the diagnosis of CA.

CONCLUSION

Although the exact mechanism still remains unclear, ADMA levels could be related to immune activation in CA. In addition, these data might suggest the higher ADMA levels in patients could be due to the perivascular inflammation and vasculitis in CA.

An unholy disease in the Holy Land: the history of anthrax between the Jordan River and the Mediterranean Sea (1909-2012)

The history of recorded cases of anthrax in human beings and animals from 1909 to 2012 in the area between the Jordan River and the Mediterranean Sea is reviewed. The disease was endemic until the middle of the 20th century, but the incidence decreased thereafter, with only sporadic cases from the 1980s onwards. Human cases have not been diagnosed in the region since 1984 and the number of episodes of animal disease has reduced to less than one per year. This decline is mostly due to the disruption of the infective cycle by improved veterinary control, including vaccination, treatment and outbreak management. A policy of reactive vaccination for 10 years of affected herds and herds grazing in their proximity has been applied. No new outbreaks have been observed in such herds after the cessation of vaccination, despite continued grazing on the same sites, so it is assumed that spore survival in such areas is shorter than 10 years. This is independent of the soil composition, which is calcareous throughout most of the relevant area. However, reemergence of anthrax, even after decades, has occurred following disturbance and heavy rainfall.

Evidence of local persistence of human anthrax in the country of georgia associated with environmental and anthropogenic factors

BACKGROUND

Anthrax is a soil-borne disease caused by the bacterium Bacillus anthracis and is considered a neglected zoonosis. In the country of Georgia, recent reports have indicated an increase in the incidence of human anthrax. Identifying sub-national areas of increased risk may help direct appropriate public health control measures. The purpose of this study was to evaluate the spatial distribution of human anthrax and identify environmental/anthropogenic factors associated with persistent clusters.

METHODS/FINDINGS

A database of human cutaneous anthrax in Georgia during the period 2000-2009 was constructed using a geographic information system (GIS) with case data recorded to the community location. The spatial scan statistic was used to identify persistence of human cutaneous anthrax. Risk factors related to clusters of persistence were modeled using a multivariate logistic regression. Areas of persistence were identified in the southeastern part of the country. Results indicated that the persistence of human cutaneous anthrax showed a strong positive association with soil pH and urban areas.

CONCLUSIONS/SIGNIFICANCE

Anthrax represents a persistent threat to public and veterinary health in Georgia. The findings here showed that the local level heterogeneity in the persistence of human cutaneous anthrax necessitates directed interventions to mitigate the disease. High risk areas identified in this study can be targeted for public health control measures such as farmer education and livestock vaccination campaigns.

Awareness and attitude toward zoonoses with particular reference to anthrax among cattle owners in selected rural communities of Zimbabwe

We conducted a cross-sectional study to assess cattle owners' awareness, perceptions, and attitudes toward zoonoses, with particular emphasis regarding anthrax. Data on awareness of zoonoses, clinical signs of anthrax in animals and human, its routes of transmission and methods of prevention, the families' consumption habits of anthrax-infected carcasses, and other family activities that increase exposure to anthrax were collected using an interviewer-administered questionnaire. A total of 41.4% (135/326) of the farmers were from high-anthrax-risk districts, whereas 28.5% and 30.1% were from medium- and low-risk districts, respectively. Overall, the level of awareness amongst the farmers for the named zoonoses were rabies (88.7%), anthrax (71.5%), and brucellosis (20.9%). Except for anthrax, awareness of other zoonoses did not differ significantly (p>0.05) among the district categories. Farmers from anthrax high-risk districts were significantly more aware of anthrax compared to those from moderate- (p=0.000) and low- (p=0.000) risk districts. All of the farmers were aware that anthrax occurs in cattle, and 73% indicated the presence of unclotting blood oozing from natural orifices as a consistent finding in cattle that died of anthrax, whereas 86.7% of them indicated the presence of skin lesions as the most common sign of the disease in humans. The good efficacy of human anthrax treatment (58.3%), slaughter of moribund cattle and selling of meat from cattle found dead to unsuspecting consumers (59.8%), reluctance to lose animals (47.9%), and forgetting about anthrax (41.1%) were cited as the major reasons for consuming anthrax-infected carcasses. Given that 75.2% of cattle owners indicated that they would not consume meat from cattle found dead, because they were discouraged by veterinary authorities, introducing meat inspection services is likely to have a positive impact in preventing human anthrax outbreaks in Zimbabwe.

Cluster analysis of host cytokine responses to biodefense pathogens in a whole blood ex vivo exposure model (WEEM)

Background

Rapid detection and therapeutic intervention for infectious and emerging diseases is a major scientific goal in biodefense and public health. Toward this end, cytokine profiles in human blood were investigated using a human whole blood ex vivo exposure model, called WEEM.

Results

Samples of whole blood from healthy volunteers were incubated with seven pathogens including Yersinia pseudotuberculosis, Yersinia enterocolitica, Bacillus anthracis, and multiple strains of Yersinia pestis, and multiplexed protein expression profiling was conducted on supernatants of these cultures with an antibody array to detect 30 cytokines simultaneously. Levels of 8 cytokines, IL-1α, IL-1β, IL-6, IL-8, IL-10, IP-10, MCP-1 and TNFα, were significantly up-regulated in plasma after bacterial exposures of 4 hours. Statistical clustering was applied to group the pathogens based on the host response protein expression profiles. The nearest phylogenetic neighbors clustered more closely than the more distant pathogens, and all seven pathogens were clearly differentiated from the unexposed control. In addition, the Y. pestis and Yersinia near neighbors were differentiated from the B. anthracis strains.

Conclusions

Cluster analysis, based on host response cytokine profiles, indicates that distinct patterns of immunomodulatory proteins are induced by the different pathogen exposures and these patterns may enable further development into biomarkers for diagnosing pathogen exposure.

Lessons learned from the investigation of a cluster of cutaneous anthrax cases in Connecticut

In 2007, two cases of cutaneous anthrax associated with West African drum making were reported in Connecticut in a drum-maker and his child. Although both cases were due to exposure to naturally occurring Bacillus anthracis from imported animal hides, ensuing investigative and remediation efforts were affected by the intentional B anthracis attacks in 2001. To share our experience of responding to an outbreak of anthrax in the biologic terrorism preparedness era, we summarize Connecticut's investigation and describe lessons learned. Laboratory capacity to rapidly assist in diagnosing anthrax, collaborative associations between epidemiologists and law enforcement personnel, and training in use of the Incident Command System, all these a result of public health preparedness, enhanced the initial recognition and subsequent investigation of these anthrax cases. However, without established guidelines for environmental risk assessment and remediation of private residences contaminated by B anthracis, challenges were encountered that resulted in a conservative and expensive approach to remediation. Without a more rigorous approach to ensuring that B anthracis spore-free hides are used, the making of animal hide drums is likely to pose a continuing risk for anthrax to those working with contaminated hides and those exposed to subsequently contaminated environments.

Ecological niche modelling of the Bacillus anthracis A1.a sub-lineage in Kazakhstan

BACKGROUND

Bacillus anthracis, the causative agent of anthrax, is a globally distributed zoonotic pathogen that continues to be a veterinary and human health problem in Central Asia. We used a database of anthrax outbreak locations in Kazakhstan and a subset of genotyped isolates to model the geographic distribution and ecological associations of B. anthracis in Kazakhstan. The aims of the study were to test the influence of soil variables on a previous ecological niche based prediction of B. anthracis in Kazakhstan and to determine if a single sub-lineage of B. anthracis occupies a unique ecological niche.

RESULTS

The addition of soil variables to the previously developed ecological niche model did not appreciably alter the limits of the predicted geographic or ecological distribution of B. anthracis in Kazakhstan. The A1.a experiment predicted the sub-lineage to be present over a larger geographic area than did the outbreak based experiment containing multiple lineages. Within the geographic area predicted to be suitable for B. anthracis by all ten best subset models, the A1.a sub-lineage was associated with a wider range of ecological tolerances than the outbreak-soil experiment. Analysis of rule types showed that logit rules predominate in the outbreak-soil experiment and range rules in the A1.a sub-lineage experiment. Random sub-setting of locality points suggests that models of B. anthracis distribution may be sensitive to sample size.

CONCLUSIONS

Our analysis supports careful consideration of the taxonomic resolution of data used to create ecological niche models. Further investigations into the environmental affinities of individual lineages and sub-lineages of B. anthracis will be useful in understanding the ecology of the disease at large and small scales. With model based predictions serving as approximations of disease risk, these efforts will improve the efficacy of public health interventions for anthrax prevention and control.

Risk factors associated with anthrax in cattle on smallholdings

SUMMARY Unprecedented high rates of anthrax outbreaks have been observed recently in cattle and humans in Bangladesh, with 607 human cases in 2010. By enrolling 15 case and 15 control cattle smallholdings in the spatial zone in July-September 2010, we conducted a case-control study, data of which were analysed by matched-pair analysis and multivariable conditional logistic regression. Feeding animals with uprooted and unwashed grass [odds ratio (OR) 41·2, 95% confidence interval (CI) 3·7-458·8, P=0·003], and feeding water hyacinth (Eichhornia crassipes) (OR 22·2, 95% CI 1·2-418·7, P=0·039) were independent risk factors for anthrax in cattle.