Brucella melitensis Biovar 1 and Brucella abortus S19 Vaccine Strain Infections in Milkers Working at Cattle Farms in the Khartoum Area, Sudan
May
Brucella melitensis Biovar 1 and Brucella abortus S19 Vaccine Strain Infections in Milkers Working at Cattle Farms in the Khartoum Area, Sudan
Amira E. F. Osman 0 1 2
Abdullahi N. Hassan 0 1 2
Ali E. Ali 0 1 2
Theresia H. Abdoel 0 1 2
Henk L. Smits 0 1 2
0 Received: August 6 , 2014
1 Academic Editor: James E Samuel, Texas A&M Health Science Center , UNITED STATES
2 1 University of Alzaiem Alazhari, Khartoum, Sudan, 2 KIT Biomedical Research, Royal Tropical Institute , Amsterdam , The Netherlands
Conclusions
The isolation of the highly infectious pathogen B. melitensis from seropositive workers is
consistent with the notion that the pathogen may persist in the blood without causing overt
disease. While vaccination with strain S19 is essential for the control of bovine brucellosis
the vaccine strain may be transmitted to the human population and protective measures
remain important to prevent exposure also in view of the presence of B. melitensis. To create
awareness for this potentially severe disease more information on the prevalence of the
pathogen in different risk groups and in livestock in the Sudan is needed.
OPEN ACCESS
Competing Interests: The authors have declared
that no competing interests exist.
Brucellosis is an highly infectious and contagious zoonotic disease feared for its debilitating and
incapacitating character [1]. Brucellosis is one of the most important zoonoses and is common
in countries and communities where a large proportion of the inhabitants is involved in
livestock farming activities, people live in close contact with their animals or consume raw milk and
other dairy products prepared from fresh milk. Until recently the disease received very little
attention as a cause of illness in African countries [2,3]. Brucellosis is caused by infection with
slow-growing, small, Gram negative, cocco-bacilla bacteria of the genus Brucella [4]. Infection
of livestock is associated with infertility, late term abortions, birth of weak calf, reduced milk
production, and in males with orchitis and epididymitis [5,6]. Human brucellosis is a febrile
disease capable of masquerading as a myriad of entities, both infectious and non-infectious [7].
The disease may affect any organ system and has a tendency towards chronicity and persistence.
Brucellosis is difficult to diagnose requiring laboratory confirmation and treatment demands
prolonged use of a combination of antibiotics with in some severe cases surgery [8].
On the basis of pathogenicity, host preference and phenotypic characteristics, eleven
Brucella species are recognized of which four, Brucella melitensis, B. abortus, B. suis and, more rarely,
B. canis, cause disease in human beings [9]. Each of these species have different livestock
species as their preferred host which for B. abortus is cattle, for B. melitensis goat and sheep, for B.
suis swine and B. canis infects dogs. Brucella species are further sub-divided in subtypes or
biovars [10]. Although B. melitensis is more infectious and more often causes disease in human
beings compared to B. abortus no difference in disease presentation and severity is observed
when comparing patients infected with the two pathogens [7].
The first report on the presence of brucellosis in the Sudan dates back from 1908. Since then
a series of studies have provided serological evidence for infection in cattle, goat, sheep and
camels in different parts of Sudan [11,12]. Much fewer studies have addressed the presence of
brucellosis in the human population of the Sudan. A low seroprevalence rate (1%) was reported
for occupational contacts including butchers, slaughterhouse workers, milkers and cow
attendants in Kassala State in Central Sudan [13]. In a more recent study a seroprevalence of 9%
was reported for abattoir workers and the seroprevalence in camel nomads was as high as 60%
[14]. The identification of risk groups and knowledge of the species that is causing disease in
the human population is important for the development of a control policy, surveillance
strategy and implementation of preventive measures [15]. Vaccination of livestock is the cornerstone
for the control and prevention of brucellosis and effective and cheap life attenuated vaccines
are available including S19 for cattle, and Rev-1 for goat and sheep [16]. In this study we
investigate the presence of brucellosis among farmworkers employed at two cattle farms in
Khartoum state and applied multiple-locus variable-number tandem repeat analysis (MLVA-16) for
the identification of Brucella isolates cultured from the blood of seropositive individuals [17].
Materials and Methods
Ethics Statement
The study protocol was approved by the Ethics Committee of the Institutional Review Board
the University of Alzaiem Alazhari. An oral consent procedure approved by the Ethics
Committee because of the limited impact of the data and sample collection procedure and illiteracy
of part of the participants. The purpose of the study was explained (...truncated)