Characteristics of the 100 largest modern zoonotic disease outbreaks.

Zoonotic disease outbreaks are an important threat to human health and numerous drivers have been recognized as contributing to their increasing frequency. Identifying and quantifying relationships between drivers of zoonotic disease outbreaks and outbreak severity is critical to developing targeted zoonotic disease surveillance and outbreak prevention strategies. However, quantitative studies of outbreak drivers on a global scale are lacking. Attributes of countries such as press freedom, surveillance capabilities and latitude also bias global outbreak data. To illustrate these issues, we review the characteristics of the 100 largest outbreaks in a global dataset (n = 4463 bacterial and viral zoonotic outbreaks), and compare them with 200 randomly chosen background controls. Large outbreaks tended to have more drivers than background outbreaks and were related to large-scale environmental and demographic factors such as changes in vector abundance, human population density, unusual weather conditions and water contamination. Pathogens of large outbreaks were more likely to be viral and vector-borne than background outbreaks. Overall, our case study shows that the characteristics of large zoonotic outbreaks with thousands to millions of cases differ consistently from those of more typical outbreaks. We also discuss the limitations of our work, hoping to pave the way for more comprehensive future studies. This article is part of the theme issue 'Infectious disease macroecology: parasite diversity and dynamics across the globe'.

Identification of Bacillus anthracis, Brucella spp., and Coxiella burnetii DNA signatures from bushmeat.

Meat from wildlife species (bushmeat) represents a major source of dietary protein in low- and middle-income countries where humans and wildlife live in close proximity. Despite the occurrence of zoonotic pathogens in wildlife, their prevalence in bushmeat remains unknown. To assess the risk of exposure to major pathogens in bushmeat, a total of 3784 samples, both fresh and processed, were collected from three major regions in Tanzania during both rainy and dry seasons, and were screened by real-time PCR for the presence of DNA signatures of Bacillus anthracis (B. anthracis), Brucella spp. (Brucella) and Coxiella burnetii (Coxiella). The analysis identified DNA signatures of B. anthracis (0.48%), Brucella (0.9%), and Coxiella (0.66%) in a total of 77 samples. Highest prevalence rates of B. anthracis, Brucella, and Coxiella were observed in wildebeest (56%), dik-dik (50%), and impala (24%), respectively. Fresh samples, those collected during the rainy season, and samples from Selous or Serengeti had a greater relative risk of being positive. Microbiome characterization identified Firmicutes and Proteobacteria as the most abundant phyla. The results highlight and define potential risks of exposure to endemic wildlife diseases from bushmeat and the need for future investigations to address the public health and emerging infectious disease risks associated with bushmeat harvesting, trade, and consumption.

Rodent control to fight plague: field assessment of methods based on rat density reduction.

Rodents represent a serious threat to food security and public health. The extent to which rodent control can mitigate the risk from rodent-borne disease depends on both the effectiveness of control in reducing rodent abundance and the impact on disease epidemiology. Focusing on a plague-endemic region of Madagascar, this study compared the effectiveness of 3 methods: live-traps, snap-traps, and rodenticides. Control interventions were implemented inside houses between May and October 2019. Tracking tiles monitored rodent abundance. Rodent fleas, the vector involved in plague transmission, were collected. Rodent populations consisted of Rattus rattus and Mus musculus. In terms of trap success, we found that our live-trap regime was more effective than snap-traps. While all 3 control strategies appeared to reduce in-house rodent activity in the short term, we found no evidence of a longer-term effect, with in-house rodent abundance in treated sites comparable to non-treatment sites by the following month. Endemic flea, Synopsyllus fonquerniei, is a key plague vector usually found on rats living outdoors. Although we found no evidence that its abundance inside houses increased following control, this may have been due to a lack of power caused by significant variation in S. fonquerniei abundance. The presence of S. fonquerniei in houses was more likely when S. fonquerniei abundance on outdoor rats was higher, which in turn correlated with high rat abundance. Our results emphasize that control strategies need to consider this connectivity between in-house rat-flea populations and the outdoor populations, and any potential consequences for plague transmission.

Field assessment of dog as sentinel animal for plague in endemic foci of Madagascar.

The epidemiology of Yersinia pestis, the causative agent of plague, involves vectors and reservoirs in its transmission cycle. The passive plague surveillance in Madagascar targets mainly rodent and fleas. However, carnivores are routinely surveyed as sentinels of local plague activity in some countries. The aim of this study is to assess the use of domestic dog (Canis familiaris) as sentinel animal for field surveillance of plague in a highly endemic area in Madagascar. Cross-sectional surveys of plague antibody prevalence in C. familiaris were conducted in endemic areas with contrasting histories of plague cases in humans, as well as a plague free area. Rodent capture was done in parallel to evaluate evidence for Y. pestis circulation in the primary reservoirs. In 2 sites, dogs were later re-sampled to examine evidence of seroconversion and antibody persistence. Biological samplings were performed between March 2008 and February 2009. Plague antibody detection was assessed using anti-F1 ELISA. Our study showed a significant difference in dog prevalence rates between plague-endemic and plague-free areas, with no seropositive dogs detected in the plague free area. No correlation was found between rodents and dog prevalence rates, with an absence of seropositive rodents in some area where plague circulation was indicated by seropositive dogs. This is consistent with high mortality rates in rodents following infection. Re-sampling dogs identified individuals seropositive on both occasions, indicating high rates of re-exposure and/or persistence of plague antibodies for at least 9 months. Seroconversion or seropositive juvenile dogs indicated recent local plague circulation. In Madagascar, dog surveillance for plague antibody could be useful to identify plague circulation in new areas or quiescent areas within endemic zones. Within active endemic areas, monitoring of dog populations for seroconversion (negative to positive) or seropositive juvenile dogs could be useful for identifying areas at greatest risk of human outbreaks.

The effectiveness of biosecurity interventions in reducing the transmission of bacteria from livestock to humans at the farm level: A systematic literature review.

Zoonotic bacterial infections are a health hazard for people who are in regular contact with livestock at the farm level. Improved biosecurity can limit zoonotic pathogen transmission within farms. The aim of this review was to summarize the effectiveness of farm-level biosecurity interventions in reducing bacterial transmission from animals to people who lived, worked in or visited farms. A systematic literature review was conducted using Embase, Ovid Medline and Agris databases, which were searched on 7th of July 2019, limited to English language papers but with no time exclusion criteria. A narrative synthesis was undertaken utilizing the Centre for Reviews and Dissemination approach, reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias within and across the included studies was performed using established checklists. Out of 869 studies retrieved through database searches, 11 studies were selected. In addition, three studies were found through study reference lists. Fourteen studies were therefore included in this review. Biosecurity interventions were grouped into five categories: hand washing, sanitization and hygienic measures (six studies); personal protective equipment (five studies); vaccination (two studies); other interventions (e.g. air ventilation flap) (four studies); and routine farm activities (two studies). Across studies that investigated odds of human colonization or infection (three studies), odds were seen to both be increased and decreased through use of tested biosecurity measures. Large confidence intervals that often crossed the threshold of an odds ratio equal to 1 were found. Most of the studies' overall risk of bias was 'medium risk' (11 studies), with selection bias domains generally being scored 'medium risk.' Biosecurity interventions are potentially beneficial in reducing bacterial transmission from animals to humans. However, more high-quality evidence is needed to increase certainty in which interventions, in which contexts, are most effective from the human health perspective.

Epitope-Based Vaccine of a Brucella abortus Putative Small RNA Target Induces Protection and Less Tissue Damage in Mice.

Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in humans and animals. Currently available live attenuated vaccines against brucellosis still have drawbacks. Therefore, subunit vaccines, produced using epitope-based antigens, have the advantage of being safe, cost-effective and efficacious. Here, we identified B. abortus small RNAs expressed during early infection with bone marrow-derived macrophages (BMDMs) and an apolipoprotein N-acyltransferase (Int) was identified as the putative target of the greatest expressed small RNA. Decreased expression of Int was observed during BMDM infection and the protein sequence was evaluated to rationally select a putative immunogenic epitope by immunoinformatic, which was explored as a vaccinal candidate. C57BL/6 mice were immunized and challenged with B. abortus, showing lower recovery in the number of viable bacteria in the liver, spleen, and axillary lymph node and greater production of IgG and fractions when compared to non-vaccinated mice. The vaccinated and infected mice showed the increased expression of TNF-α, IFN-γ, and IL-6 following expression of the anti-inflammatory genes IL-10 and TGF-ß in the liver, justifying the reduction in the number and size of the observed granulomas. BMDMs stimulated with splenocyte supernatants from vaccinated and infected mice increase the CD86+ marker, as well as expressing greater amounts of iNOS and the consequent increase in NO production, suggesting an increase in the phagocytic and microbicidal capacity of these cells to eliminate the bacteria.

Salmonellosis: A food borne zoonotic and public health disease in Egypt.

Salmonellosis is an important food borne disease of public health significance. Global estimates of the disease burden shows more than 20 million cases and 0.15 million deaths annually. The disease caused by a variety of Salmonella organisms worldwide. Salmonella pathogens are belonging to family Enterobacteriaceae that are known to infect many hosts inducing variable clinical diseases pictures. Typhoidal and non-typhoidal Salmonellae are common diseases among Egyptians with severe socioeconomic losses. Different species of animals and poultry as well as their products are the main sources and reservoirs for zoonotic human illness. Enteric fever and gastroenteritis are the main clinical manifestations in patients. Great attention toward salmonellosis drug resistance, prevention and control should be considered.

Computational design of a novel multi-epitope vaccine against Coxiella burnetii.

Query fever is a zoonotic disease caused by Coxiella burnetii. There is no universal method for the prevention of this disease. Recombinant vaccine is a potent strategy that can be utilized for this purpose. The current study was conducted to develop a multi-epitope vaccine against Coxiella burnetii. Hence, OmpA, Tuf2, GroEL, Mip and sucB antigens were used for the prediction of epitopes. Then, a multi-epitope vaccine was developed based on a molecular adjuvant and fragments that contained the best MHCI, B cell, MHCII and IFN-γ epitopes. The features of the developed vaccine including physicochemical parameters, antigenicity and protein structures were assessed. Also, interaction between the developed vaccine and TLR4/MD2 receptor along with molecular dynamics of the ligand-receptor complex were investigated. Finally, the codon adaptation and cloning were conducted for the developed vaccine. According to the results, molecular weight, instability index, antigenicity and random coil percentage of the developed vaccine were 54.4 kDa, 32.84, 1.1936 and 34.92%, respectively. Besides, residues distribution in core region of the refined model was 85%. The results demonstrated that the developed vaccine could dock to its receptor with the lowest energy of -976.7 as well as RMSD value of the complex was between 0.15 and 0.22 nm. Also, the results showed that CIA index of the codon adapted sequence was 0.95. Finally, cloning results revealed that nucleotide sequence of the developed vaccine could be successfully cloned into pET-21a (+). Based on these results, it seems that the developed vaccine can be a suitable candidate to prevent Coxiella burnetii.

Erisipela suína: relato de caso no município de Cachoeiras de Macacu-RJ / Swine erysipelas: case report in the city of Cachoeiras de Macacu-RJ

Na suinocultura perdas econômicas ainda são elevadas devido aos baixos padrões de qualidade e sanidade dos animais. Dentre as afecções que afetam a produção, a erisipela é uma doença considerada importante em função dos prejuízos econômicos que causa, e pela questão de saúde pública visto ser uma zoonose. Ela é uma enfermidade do tipo hemorrágica comumente causada pela bactéria ubíqua Erysipelotrix rhusiopathiae. O objetivo deste trabalho foi relatar um caso desta afecção em uma matriz da raça Large White, de dois anos de idade, recém desmamada, não vacinada, de uma pequena granja de ciclo completo no munícipio de Cachoeiras de Macacu, estado do Rio de Janeiro. Ela amanheceu prostrada, com dificuldade de locomoção, sem febre e com manchas avermelhadas sobre toda a superfície corporal. As lesões cutâneas, ligeiramente elevadas, apresentavam um formato losangular (diamante) característico e sugestivo de Erisipela. Após a identificação do problema, o animal foi isolado e tratado. O tratamento iniciou-se na manhã do mesmo dia, observando-se a regressão da maioria das lesões à tarde e na manhã seguinte. A suspeita clínica foi confirmada através do diagnóstico terapêutico, sendo a associação de penicilina e estreptomicina eficiente no tratamento.

In swine industry, economic losses are still high due to low standards of quality and health of animals. Among the diseases that affect production, erysipelas is a disease considered important due to the economic losses it causes, and because of the public health issue as it is a zoonosis. It is a hemorrhagic type disease commonly caused by the ubiquitous bacteria Erysipelotrix rhusiopathiae. The aim of this study was to report a case of this condition in a Large White breed sow, two years old, recently weaned, not vaccinated, from a small pig farm (farrow to finish operation) in the municipality of Cachoeiras de Macacu, state of Rio de Janeiro. The sow was prostrate and with limited mobility, without fever and with reddish spots on the entire body surface. The cutaneous lesions were elevated, with a characteristic diamond shape suggestive of erysipelas. After identifying the problem, the animal was isolated and treated. The treatment started in the morning of the same day, observing the regression of most lesions in the afternoon and the following morning. The clinical diagnosis was confirmed through therapeutic diagnosis, and the association of penicillin and streptomycin was efficient in the treatment.

Soropositividade para Leptospira sp. e sorogrupos predominantes em cães do Pantanal Brasileiro / Seropositivity for Leptospira sp. and predominant serogroups in dogs from the Brazilian Pantanal

Em face à grande importância que a leptospirose possui no contexto sanitário mundial, tanto no aspecto humano como animal, este estudo teve por objetivo realizar a pesquisa de anticorpos anti-Leptospira sp. pela técnica de Soroaglutinação Microscópica (SAM) em 429 amostras de soros de cães provenientes de quatro municípios (Poconé/MT, Santo Antônio de Leverger/MT, Barão de Melgaço/MT e Corumbá/MS) localizados na região do Pantanal Brasileiro, bem como foram verificadas possíveis associações entre os resultados dos exames sorológicos e respostas aos questionários epidemiológicos aplicados aos proprietários. Do total de cães avaliados pela SAM (título ≥100), verificou-se que 34 (7,93%; IC 95%: 5,63%-11,00%) cães tinham anticorpos anti-Leptospira sp. Os títulos encontrados variaram entre 100 e 1600 e todos os municípios analisados tinham cães sororreagentes ao agente pesquisado. O sorogrupo reator mais frequente foi o Icterohaemorrhagiae, seguido pelo Australis. Por outro lado, foram observadas menores proporções de cães reagentes aos sorogrupos Tarassovi, Hebdomadis, Autumnalis e Grippotyphosa. As variáveis associadas com a ocorrência de leptospirose foram habitat rural (P<0,01) e área alagável (P=0,01). Estes resultados demonstram que os cães da região pantaneira tiveram contato com agentes do gênero Leptospira, o que representa uma informação relevante para a saúde pública local devido à importância zoonótica da doença.

Given the great importance that leptospirosis has the global health context, both in human and animal aspect, this study aimed to search for antibodies anti-Leptospira sp. by the technique of microscopic agglutination test (MAT) in 429 samples of sera from dogs from four municipalities (Poconé/MT, Santo Antônio de Leverger/MT, Barão de Melgaço/MT and Corumbá/MS) located in the Brazilian Pantanal region, in order for determine associations between the results of the serological tests and answers to epidemiological questionnaires applied to owners. Of the total dogs evaluated by MAT (titer ≥100), it was verified that 34 (7.93%, 95% CI: 5.63% -11.00%) dogs had antibodies against Leptospira sp. The titers found ranged from 100 to 1600 and all municipalities analyzed had seroreactive dogs for the investigated agent. The most frequent serogroup reactor was Icterohaemorrhagiae, followed by Australis. On the other hand, smaller proportions of reactive dogs were observed for serogroups Tarassovi, Hebdomadis, Autumnalis and Grippotyphosa. The variables associated with the occurrence of leptospirosis were rural habitat (P<0.01) and flooded area (P=0.01). These results demonstrate that dogs from the Pantanal region had contact with agents of the genus Leptospira, which represents information relevant to local public health due to the zoonotic importance of the disease.