Epidemiology of brucellosis in Iran: A comprehensive systematic review and meta-analysis study
Introduction
Brucellosis, also known as “undulant fever”, “Mediterranean fever”, “Malta fever”, “Gibraltar fever”, “thousandface disease”, “raging fever” or “melitococci disease”, is an important world-wide disease in both human and animals that caused by Gram-negative bacteria, Brucella spp. [1], [2]. Human might be infected by Brucella abortus, Brucella canis, Brucella suis and Brucella melitensis. Infection intensity Brucella types such that B. abortus and B. canis cause to mild disease while in brucellosis caused by B. suis, the duration is longer and symptoms are more severe. Brucella melitensis is the most abundant and acute type followed by different disturbances [3], [4]. Brucellosis is almost transmitted by indirect or direct contact with infected animals or their products, invariably so known as zoonotic disease [5]. The disease affects people of all age groups and of both men and women, worldwide [6]. The disease is a major public health issue throughout the world and one of the most socioeconomic problems in many developing countries, especially in the Mediterranean basin, north and east Africa, the Middle East, the Arabian Peninsula, the Indian subcontinent and parts of South America and central Asia [7]. In these areas, poor diagnosis and treatment may result in serious complications [8]. Brucellosis is a contagious, costly disease of ruminant animals that also affects humans [5], [7]. According to the WHO reports, annually more than 500,000 incident cases of brucellosis are notified worldwide especially from developing countries, and that for every case diagnosed with the disease, four cases go undetected [9], [10], [11], [12]. Dairy products, climatic situation, environmental hygiene, and socio-economic conditions are main factors of infectiousness and transmission of brucellosis. Human contact with infected animals is the most common mode of transmission [13]. There is a considerable variation in the frequency of brucellosis in different parts of Iran. The incidence varied between 98 and 130 per 100,000 populations. Southern parts of Iran have the lowest incidences of this infection [14]. Human brucellosis is a disease with a wide range of clinical signs, presenting various diagnostic difficulties because its symptoms are similar to those of many other diseases [15]. The importance of this disease is not limited to physical complications, and it is considered to be one of the most important challenges for economic development in many countries such as Iran, whose economic growth and employment still depend on livestock and agriculture [16], [17], [18]. Iran stands in the second rank regarding the prevalence of Malta fever worldwide [19]. Most common symptoms of brucellosis include undulant fever, weakness, night sweats with peculiar odor and chills [20]. The wide spectrum of brucellosis symptoms in human has led to the fact that diagnosed people are considerably less than the actual number of the infected population [21], [22]. Each year, more than 500,000 new cases are reported, and this figure underestimates the magnitude of the problem [23]. This disease causes high clinical morbidity and various clinical manifestations in humans such as fever, arthralgia and sweating, and any organ can be affected include encephalitis, meningitis, spondylitis, orchitis, prostatitis, arthritis and endocarditic [24]. Although brucellosis in domestic animals has been controlled in most developed countries, it remains an important public and animal health problem in the developing countries. The disease is endemic in Iran [25].
Due to serious and destroying complication of this infection, early and fast diagnosis and proper treatment of this infection can prevent from the following disabilities [26]. Quality of veterinary service, availability of economic resources, spread of the disease, type of husbandry and the degree of involvement of ranchers are most important factors that should be considered in adopting brucellosis control/eradication programs. Iran is an endemic area for brucellosis which is a serious public health issue in the country [27], [28]. This infection is a very important health problem in Iran and according to the data derived from active surveillance during 2001–2005, the incidence of the disease are 120–400 per 100,000 people [29]. According to the annual report of Center for Disease Control in Iran, the incidence rate of brucellosis was 39 per 100,000 and 30 per 100,000 populations in 2005 and 2007, respectively. In addition, the incidence rate of infection has increased to 130 per 100,000 populations in west of Iran in last years. The incidence rate of this infection was 45 per 100,000 populations in Hamadan in 2008 [30], [31], [32]. One of the important reasons of increasing rate of brucellosis is disability in control of disease in animals. In addition, different clinical manifestations of brucellosis in humans and difficulty in definite diagnosis of the disease caused the incidence rate to be under estimated [21], [22].
A database review indicates that numerous studies are carried out on the epidemiological features of Malta fever in Iran. An authentic measurement for the epidemiological and clinical features of Malta fever can be developed through combination of the research findings using meta-analysis [33]. Furthermore, through systematic review and meta-analysis of the results, we can provide well-grounded findings that can be used in public health policy-making and proposing suggestions for further research [34]. The current research aimed to study the epidemiological features of brucellosis in Iran through carrying out a meta-analysis.
Section snippets
Search strategy
International databases (ISI Web of Science, PubMed, Scopus, google scholar and Science Direct) and four national scientific search engines including Medlib (www.medlib.ir), Magiran (www.Magiran.com), Iranian Scientific Information Database (www.sid.ir) and “IranMedex” (www.iranmedex.ir) for relevant articles were searched (up to July 2016) by using the following keywords: “Brucellosis”, “Brucella”, “incidence”, “epidemiology”, “undulant fever”, “Mediterranean fever”, “Malta fever”, “Gibraltar
Results
A total of 8326 articles were retrieved by the database search. Summary of the literature search and study selection showed in Fig. 1. In a first screening process, 4275 of papers were excluded due to duplication, and 4051 articles were retained for title and abstract assessment. In a secondary screening process, 3674 of publications were excluded based on title and abstract evaluation, and 377 articles were retained for detailed full-text evaluation. After full-text evaluation, 34 articles
Discussion
Brucellosis remains endemic in most areas of the world although in much of Northern Europe, Australia, the US and Canada it has been eradicated or virtually eradicated from livestock following lengthy and expensive control programs [70]. The Eastern Mediterranean that consists of 22 countries, including Iran is one of the most important endemic regions for brucellosis infection. Annually more than half a million incident cases of brucellosis are notified from countries in this region [10]. The
Conclusion
Brucella infection remains an important public health issue in endemic areas such as Iran, and much remains to be done to reach the aim of controlling human and animal infection. According to the results of this study, annually incidence rate of brucellosis is in a high rate in some parts of Iran, and likely to rise; thus, measures should be taken to control the transmission pathway of infection from domestic animals and their products to human. In addition, the rapid identification of sick
Ethical approval
Not required.
Funding
No funding.
Authors' contribution
MS and SM contributed to the conception and design of the work; the acquisition, analysis, and interpretation of data for the work. FMJ contributed to data collection and interpretation of data for the work. RM contributed to design of the work, data collection and final approval of the version to be published. MS and FMJ contributed in data analysis, Drafting the work and revising it critically for important intellectual content. RM and SM contributed in the revising the draft and agreement to
Conflict of interest
Authors declares that there are no conflict of interests in the present study.
Informed consent
All authors approved the final version of the manuscript.
Acknowledgement
The authors are greatly thankful to Saadat Pirouzi for help with the English language version of this paper. Also, we would like to thank the director and principal of Iran university of medical sciences for their constant encouragement and support of research for this study.
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