Brucellosis, a neglected disease

Summary

Brucellosis is a zoonosis(1), an infectious disease due to bacteria of the Brucella genus, which can affect most animals - domestic and wild species. In animals, the infection may cause abortions in females, epididymo-orchitis in males and, less frequently, arthritis or bursitis in both. Mucosal contact with aborted fetuses and fetal membranes, which contain large amounts of the bacteria, is an important means of transmission in livestock.

 

Fifty years ago, the Brucella genus was considered to contain only 3 species: Brucella abortusBrucella melitensis, and Brucella suis. Since the early 1960s, new species have been identified as belonging to the Brucella genus. Although the pathogenesis and histologic lesions of B. abortusB. melitensis, and B. suis in their preferred hosts have not changed, additional knowledge on the pathology of these brucellae in new hosts, or of new species of Brucella in their preferred hosts, has been obtained (Olsen et al, 2014). 

 

To this day, brucellosis remains a neglected human zoonosis that is emerging or reemerging in many parts of the world. It places significant burdens on human healthcare systems and limits the economic potential of individuals, communities, and nations. The implementation of public policy focused on mitigating the socioeconomic effects of brucellosis in human and animal populations is needed. The interdisciplinary “One Health” nature of the effects that brucellosis has indicate that collaboration of veterinary, medical, public health, cultural, economic and social experts is needed to effect a change in disease burden (Berthe et al, 2018; Franc et al, 2018).

(1) Zoonosis : a disease, communicable from animals to humans under natural conditions, due to microbes, parasites or prions capable of infecting at least one vertebrate animal, transmission taking place from animal to humans or vice-versa.

A disease with a thousand faces

discovered by Sir David Bruce and Thermistocles Zammit

This disease is thought to have existed since ancient times. "Malta fever", "Undulant fever", "Mediterranean fever", "Melitococcosis", "Epizootic Abortion", different names given to the same disease, according to the place, the time and even the species that are concerned. 

First evidence of brucellosis was revealed using proteomic analyses applied to an ancient archeological solid residue of Egyptian cheese found in the tomb of Ptahmes, mayor of Memphis and high-ranking official under the Pharaohs Sethi I and Ramses II (1290–1213 B.C.) of the XIX dynasty. For more information, see Greco et al. Anal. Chem.2018, 90, 16: 9673-9676.

Lessons from the History

Wyatt et al, 2016

The disease we now know as brucellosis was first discovered in the 1850s in Malta. It came to the attention of British medical officers serving on the island after the Crimean War.

[relayed from Journal of Maltese History, volume 5, number 1.]

Brucellosis in Humans

The epidemiology of human brucellosis, the commonest zoonotic infection worldwide, has drastically changed over the past decade because of various sanitary, socioeconomic, and political reasons, together with the evolution of international travel. The highest prevalence of human disease is currently found in areas of Africa, Asia, Latin America, and the Middle East (Hull & Schumaker, 2018).

More than half a million cases are reported worldwide, although due to the wide-ranging and nonspecific nature of clinical signs, the true number may be much higher. In endemic countries, prevalence rates exceed 10 per 100 000. Multiple studies have demonstrated that addressing brucellosis in animal reservoirs is the most cost-efficient mechanism for controlling human brucellosis.

Main transmission routes

Humans generally acquire the disease through direct contact with infected animals, by eating or drinking contaminated animal products. The signs and symptoms of brucellosis are extensive and they can be similar to many other febrile illnesses. Some individuals may develop long-term chronic symptoms, and may evolve to a chronic illness that may induce serious complications, particularly at osteo-articular level.

see CDC - Raw milk questions and answers

High economical impacts

In farms, economic loss may be direct (abortion) or indirect (milk loss and sterility ; Franc et al, 2018). However, the major economic issue is that French, European or International regulations state that only animals that come from officialy free herds may be used for trade and even for the import of semen, ova and embryos. 

World Health organisation estimated the Global and Regional Disease Burden of 22 Foodborne Bacterial, Protozoal, and Viral Diseases in 2010. The authors synthesized data on the number of food borne illnesses, sequelae, deaths, and Disability Adjusted Life Years (DALYs), for brucellosis. For more information, see Kirk MD, Pires SM, Black RE, Caipo M, Crump JA, Devleesschauwer B, et al. (2015). PLoS Med 12(12): e1001921.

Occurence in Europe

ECDC-EFSA report on zoonoses

[relayed from ECDC-EFSA report ] Brucellosis is a severe disease with most infected human cases hospitalised and with one death reported in 2017. This figure presents the number of domestically acquired confirmed brucellosis cases in humans, and prevalence of Brucella test‐positive cattle, sheep and goat herds in Europe, 2017. Tables and figures are available in downloadable files. For more information, see the ECDC website.