Epidemiological and clinical aspects of human Brucella suis infection in Polynesia

Immune Responses Potentially Involved in the Gestational Complications of Brucella Infection

Infection by Brucella species in pregnant animals and humans is associated with an increased risk of abortion, preterm birth, and transmission of the infection to the offspring. The pathogen has a marked tropism for the placenta and the pregnant uterus and has the ability to invade and replicate within cells of the maternal-fetal unit, including trophoblasts and decidual cells. Placentitis is a common finding in infected pregnant animals. Several proinflammatory factors have been found to be increased in both the placenta of Brucella-infected animals and in trophoblasts or decidual cells infected in vitro. As normal pregnancies require an anti-inflammatory placental environment during most of the gestational period, Brucella-induced placentitis is thought to be associated with the obstetric complications of brucellosis. A few studies suggest that the blockade of proinflammatory factors may prevent abortion in these cases.

Seroprevalence and Risk Factors Related to Bovine Brucellosis in Continental Ecuador

Bovine brucellosis is a worldwide zoonotic contagious disease. According to World Animal Health Information System reports Ecuador has presented an increasing number of bovine brucellosis outbreaks in the continental territory over the past years (756 in 2018 versus 964 in 2021), generating economic losses for producers and causing a risk to public health. A cross-sectional study was conducted to investigate the seroprevalence of bovine brucellosis and associated risk or protective factors between May and June 2018. This stratified random study was implemented in 290 cattle herds located in the 23 provinces of continental Ecuador, which represents a total of 3737 cows aged 24 months or older. A competitive ELISA was used to detect Brucella antibodies. Simultaneously, an epidemiological survey was implemented to assess the brucellosis risk or protective factors. The apparent prevalence of bovine brucellosis at the herd level was 21.3% (95% CI: 16.8-26.6) and 6.2% (95% CI: 5.5-7) at the animal level. Univariate and multivariate logistic regression analyses were performed to determine the relationship between the potential factors associated with the presence of bovine brucellosis. The risk factors identified after multivariate analysis were a surface in ha per herd > 70 ha (OR = 2.73; 95% CI: 1.18-6.32) and the number of parturitions per animal (two or more with OR ≥ 1.8 and p-value ≤ 0.047). On the contrary, the protective factors were the region (farms located in the eastern region) and the absence of reported clinical signs. In addition, in herds where extensive production predominates, farmers have a low level of knowledge, and the farm biosecurity level is low. These results can guide the authorities in managing the risk factors identified, understanding the current epidemiological situation in Ecuador, improving the bovine brucellosis control program and food safety, as well as increase the one-health approach.

Molecular Investigations of Two First Brucella suis Biovar 2 Infections Cases in French Dogs

Despite Brucella suis biovar 2's (BSB2) active circulation in wildlife, no canine infections have been reported. The present paper is the first to describe two cases of BSB2 infections in French dogs. The first case occurred in 2020 and concerned a 13-year-old male neutered Border Collie with clinical signs of prostatitis. The urine culture revealed the excretion of significant levels of Brucella in the sample. The second case concerned a German Shepherd with bilateral orchitis, in which it was possible to detect Brucella colonies following neutering. HRM-PCR and classical biotyping methods classified both isolated strains as BSB2, in contrast to expected B. canis, which is usually the etiological agent of canine brucellosis in Europe. The wgSNP and MLVA analyses highlighted the genetic proximity of two isolates to BSB2 strains originating from wildlife. No pig farms were present in the proximity of either dog's residence, ruling out potential spill over from infected pigs. Nevertheless, the dogs used to take walks in the surrounding forests, where contact with wildlife (i.e., wild boars or hares, or their excrements) was possible. These cases highlight the importance of adopting a One Health approach to control the presence of zoonotic bacteria in wild animals and avoid spillovers into domestic animals and, potentially, humans.

The Lanzhou Brucella Leak: The Largest Laboratory Accident in the History of Infectious Diseases?

An inadequacy in sanitizing processes in a biopharmaceutical plant in Lanzhou, China, during July and August 2019, led to the aerosolization of Brucella that was subsequently spread through wind to nearby settlements and academic institutes, resulting in >10 000 human brucellosis cases, as of November 2020. The leak, possibly the largest laboratory accident in the history of infectious diseases, underlines the particular characteristics of Brucella that have made the pathogen a historical entity in biodefense research and a major cause of laboratory-associated infections. It further underlines the need for enhanced vigilance and strict regulatory interventions in similar facilities.

Prevalence and factors associated with human brucellosis in livestock professionals

OBJECTIVE

The objective of this study is to estimate the seroprevalence of human brucellosis in livestock professionals and analyze the factors associated with brucellosis focusing on sociodemographic variables and the variables of knowledge and practices related to the characteristics of the activities carried out in livestock.

METHODS

This is a cross-sectional seroepidemiological study with a population of 131 workers of butchers, slaughter rooms, and slaughterhouse and 192 breeders sampled randomly in Namibe province, Angola. The data were obtained from the collection of blood and use of questionnaires. The laboratory tests used were rose bengal and slow agglutination. The questionnaire allowed us to collect sociodemographic information and, specifically on brucellosis, it incorporated questions about knowledge, attitudes, and behaviors of livestock professionals. In addition to the descriptive statistical approach, we used the Chi-square test of independence, Fisher's test, and logistic regression models, using a significance level of 10%.

RESULTS

The general weighted prevalence of brucellosis was 15.6% (95%CI 13.61-17.50), being it 5.3% in workers and 16.7% (95%CI 11.39-21.93) in breeders. The statistical significance was observed between human seroprevalence and category (worker and breeder) (p < 0.001) and education level (p = 0.032), start of activity (p = 0079), and service location (p = 0.055). In a multivariate context, the positive factor associated with brucellosis in professionals was the professional category (OR = 3.54; 95%CI 1.57-8.30, related to breeders in relation to workers).

CONCLUSIONS

Human brucellosis in livestock professionals is prevalent in Namibe province (15.6%), where the professional category was the most important factor. The seroprevalence levels detected are high when compared with those found in similar studies.

OBJECTIVO

Estimar a seroprevalência da brucelose humana em profissionais da pecuária e analisar os factores associados à brucelose com foco em variáveis sociodemográficas, de conhecimento e práticas relativas às características das actividades desenvolvidas na pecuária.

MÉTODOS

Estudo transversal seroepidemiológico em população de 131 trabalhadores de talhos, salas de abate e matadouro e 192 criadores amostrados aleatoriamente na província do Namibe, Angola. Os dados foram obtidos por meio de colheita de sangue e aplicação de questionário. Os testes laboratoriais utilizados foram o Rosa de Bengala e a aglutinação lenta em tubos. O questionário permitiu recolher informação sociodemográfica e, especificamente sobre a brucelose, incorporou questões sobre conhecimento, atitudes e comportamentos dos profissionais da pecuária. Além da abordagem estatística descritiva, foram utilizados os testes de Independência do Qui-quadrado, Fisher e modelos de regressão logística, utilizando um nível de significância de 10%.

RESULTADOS

A prevalência geral ponderada da brucelose foi de 15.6% (IC95% 13.61-17.50), sendo 5.3% em trabalhadores e 16.7% (IC95% 11.39-21.93) em criadores. A significância estatística foi observada entre a seroprevalência humana e a categoria (trabalhador e criador) (p < 0.001) e o nível de instrução (p = 0.032), início de actividade (p = 0.079) e local de serviço (p = 0.055). Em um contexto multivariado, o factor positivamente associado à brucelose em profissionais foi a categoria profissional (OR = 3.54; IC95% 1.57-8.30, relativo aos criadores em relação a trabalhadores).

CONCLUSÕES

A brucelose humana em profissionais da pecuária é prevalente na província do Namibe (15.6%), onde a categoria profissional foi o factor mais relevante. Os níveis de seroprevalência detectados são elevados se comparados com outros encontrados em estudos semelhantes.

Boar hunting and brucellosis caused by Brucella suis

Brucellosis remains as a significant public health concern in many areas where the infection persists in domestic hosts (i.e. goats, cattle, and domestic swine) with subsequent risk of transmission to human populations. Brucellosis caused by B. suis remains an important threat to human populations in many countries exposed to domestic and feral swine. In the U.S., swine brucellosis has been under control for many years. Meanwhile, it is a widespread infection among feral swine, particularly in the Southeastern United States; and exposure to infected animals pose a growing threat to humans. We present the case of a 31-year male hunter who six weeks after a knife injury to his hand while field dressing a wild boar, developed a febrile illness associated with hematologic abnormalities and splenic abscesses caused by Brucella suis infection.

High Incidence of Respiratory Involvement in a Cluster of Brucella suis-Infected Workers from a Pork Processing Plant in Argentina

Epidemiological and clinical aspects of Brucella suis infection in 17 workers from a pork processing plant in Argentina occurring between January 2014 and July 2015 are presented. All patients reported working 9 h daily without adequate personal protection garment. Blood cultures were positive for Brucella spp. in 14 of the 17 patients (82.3%). All isolates were identified as B. suis biovar 1. Although fever, sweats, asthenia, myalgia and hepatic involvement were the most frequent clinical manifestations, an unusually high incidence of respiratory involvement was found. From 13 patients in which chest radiography was performed, four (30%) had radiological abnormalities, including lobar pneumonia in two cases (one with pleural effusion) and interstitial involvement in other two. The high frequency of respiratory involvement in our series makes necessary to consider brucellosis in the differential diagnosis of respiratory diseases in pork processing plant employees.

Brucella spp. Virulence Factors and Immunity

Brucellosis, caused by bacteria of the genus Brucella, is an important zoonotic infection that causes reproductive disease in domestic animals and chronic debilitating disease in humans. An intriguing aspect of Brucella infection is the ability of these bacteria to evade the host immune response, leading to pathogen persistence. Conversely, in the reproductive tract of infected animals, this stealthy pathogen is able to cause an acute severe inflammatory response. In this review, we discuss the different mechanisms used by Brucella to cause disease, with emphasis on its virulence factors and the dichotomy between chronic persistence and reproductive disease.

The history of brucellosis in the Pacific Island Countries and Territories and its re-emergence

There are few publications on brucellosis within the Pacific Island Countries and Territories (PICTs). The reason is possibly because the cattle population has been reportedly free of the disease for many years until a re-emergence occurred in the Fiji Islands (Viti Levu) in 2009. This paper reports on the outbreak of brucellosis in Fiji and its progression between 2009 and 2013 in the context of an overview of brucellosis in the Pacific Island community. Review of the literature found only 28 articles with the oldest record of brucellosis being in 1965 in Papua New Guinea (PNG) and from human cases in Tonga in 1980. The Fiji outbreak of Brucella abortus occurred in cattle in 2009 (Wainivesi basin) in the Tailevu province. Prior to the outbreak, Fiji declared freedom from B. abortus to OIE in 1996 after a successful eradication campaign. During the course of the outbreak investigation, serum samples were collected from between 9790 and 21,624 cattle per annum between 2009 and 2013 from 87 farms on the main island of Fiji (Viti Levu). Blood samples were tested for brucellosis using the Rose Bengal Test (RBT) in 2009 and the indirect ELISA test in subsequent years. At the time of the outbreak in Fiji (2009) the apparent prevalence in cattle was 1.50% and this has fluctuated since the outbreak. The True Prevalence (TP) for the main island in Fiji for the indirect ELISA tests was 2.40% in 2010, reached a peak of 3.49% in 2011 then reduced to 0.12% by 2013. The significant reduction in prevalence compared to 2010 is most likely due to the control programs being implemented in Fiji. The re-emergence of B. abortus in Fiji could be attributed to the lack of monitoring for the disease until 2009 combined with inadequate management of exposed animals, thus illustrating how important it is for authorities not to become complacent. Continued awareness and monitoring for brucellosis is essential if future outbreaks are to be avoided.

Cultural drivers and health-seeking behaviours that impact on the transmission of pig-associated zoonoses in Lao People's Democratic Republic

Pig rearing is an important income source in the Lao People's Democratic Republic (PDR), with many smallholder farmers using traditional free-range pig production systems. Despite the potentially significant health risks posed by pig production regarding pig-associated zoonoses, information on the sociocultural drivers of these zoonoses is significantly lacking. This review summarises the existing sociocultural knowledge on eight pig-associated zoonoses suspected to be endemic in Southeast Asia: brucellosis, Q fever (Coxiella burnetii), trichinellosis, hepatitis E virus, leptospirosis, Japanese encephalitis, Streptococcus suis and Taenia solium taeniasis-cysticercosis. It summarises current knowledge on these diseases grouped according to their clinical manifestations in humans to highlight the propensity for underreporting. A literature search was conducted across multiple databases for publications from 1990 to the present day related to the eight pig-associated zoonoses and the risk and impact connected with them, with Lao PDR as a case study. Many of these pig-associated zoonoses have similar presentations and are often diagnosed as clinical syndromes. Misdiagnosis and underreporting are, therefore, substantial and emphasise the need for more robust diagnostics and appropriate surveillance systems. While some reports exist in other countries in the region, information is significantly lacking in Lao PDR with existing information coming mainly from the capital, Vientiane. The disease burden imposed by these zoonoses is not only characterised by morbidity and mortality, but directly impacts on livelihoods through income reduction and production losses, and indirectly through treatment costs and lost work opportunities. Other factors crucial to understanding and controlling these diseases are the influence of ethnicity and culture on food-consumption practices, pig rearing and slaughter practices, hygiene and sanitation, health-seeking behaviours and, therefore, risk factors for disease transmission. Published information on the knowledge, attitudes and beliefs of people regarding pig zoonoses and their risk factors is also extremely limited in Lao PDR and the broader Southeast Asian region. The need for more transdisciplinary research, using a One Health approach, in order to understand the underlining social determinants of health and their impacts on health-seeking behaviours, disease transmission and, ultimately, disease reporting, cannot be more emphasized.

Brucellosis in low-income and middle-income countries

PURPOSE OF REVIEW

Human brucellosis is a neglected, underrecognized infection of widespread geographic distribution. It causes acute febrile illness and a potentially debilitating chronic infection in humans, and livestock infection has substantial socioeconomic impact. This review describes new information regarding the epidemiology of brucellosis in the developing world and advances in diagnosis and treatment.

RECENT FINDINGS

The highest recorded incidence of human brucellosis occurs in the Middle East and Central Asia. Fever etiology studies demonstrate brucellosis as a cause of undifferentiated febrile illness in the developing world. Brucellosis is a rare cause of fever among returning travelers, but is more common among travelers returning from the Middle East and North Africa. Sensitive and specific rapid diagnostic tests appropriate for resource-limited settings have been validated. Randomized controlled trials demonstrate that optimal treatment for human brucellosis consists of doxycycline and an aminoglycoside. Decreasing the burden of human brucellosis requires control of animal brucellosis, but evidence to inform the design of control programs in the developing world is needed.

SUMMARY

Brucellosis causes substantial morbidity in human and animal populations. While improvements in diagnostic options for resource-limited settings and stronger evidence for optimal therapy should enhance identification and treatment of human brucellosis, prevention of human disease through control in animals remains paramount.

Socio-economic, industrial and cultural parameters of pig-borne infections

The pork-processing industry has been possibly the fastest growing sector of the food industry in recent years. Specialization, genetic homogenization of the pig population, high density of the breeding population, reduced human-animal interactions, slaughter at a lower age and increased international trade of live animals and pork are parameters that affect, positively or negatively, the emergence of novel pig-borne pathogens, many of which are pig-specific, and many of which have significant zoonotic potential, as observed in recent outbreaks of Nipah virus and Streptococcus suis in Southeast Asia and China, respectively. Numerous other pathogens are transmitted to humans through direct contact with or consumption of pig products, and globalization trends in trade and human population movements have resulted in outbreaks of pig-borne diseases even in Muslim countries and in Israel, where pork consumption is religiously prohibited. The role of pigs as potential reservoirs of antibiotic-resistant pathogens or genes encoding resistance, and the role of feral pigs as a reservoir of zoonotic disease, are scientific fields in direct need of further research.

Cultural contexts of swine-related infections in Polynesia

Pig-raising is an inherent element of ancestral Polynesian culture, but pigs constitute a reservoir of potentially severe diseases for humans. Little research in this area from a social science perspective has been performed, particularly in Oceania. The objective of this study was to assess swine brucellosis awareness and protection measures in two remote Polynesian French islands. We applied quantitative methods to a small clinic-based population selected according to the presence of a history of brucellosis serology, and semistructured interviews about public health measures and veterinary access were used among key informants for qualitative methods. Most individuals interviewed did not know about brucellosis, despite repeated public awareness campaigns. Standard hygiene recommendations to protect humans and animals were not compatible with traditional practice. Innovative approaches are required for effective awareness campaigns, and to gain the confidence and close cooperation of the community, in order to implement successful control measures for communicable diseases such as brucellosis.

A rare case of seronegative culture--proven infection with Brucella suis

Brucellosis is a chronic infection produced by members of the Brucella family. Diagnosis of this condition requires either isolation of the organism in culture or positive serological tests.We describe a 27-year-old male admitted as a case of pyrexia of unknown origin (PUO), who tested negative for Brucella IgM ELISA test on preliminary evaluation but was subsequently diagnosed on the strength of positive blood and bone marrow cultures to be a case of brucellosis secondary to Brucella suis infection. In addition to highlighting the pathogenic potential of an unusual organism, this case demonstrates the unreliability of standard serological tests based on the Brucella melitensis antigen for infection with other species of Brucella.