1. HUMAN BRUCELLOSIS IN NORTH-WEST ECUADOR: PREVALENCE
TYPIFYING Brucella spp. AND RISK FACTORS
Jorge Ron-Román1-2-4, Washington Benítez-Ortíz1, Lenin Ron-Garrido1, Dirk Berkvens2, Jef Brandt2, David Fretin3 and Claude Saegerman4.
Brucellosis 2011, International Research Conference; Including the 64th Brucellosis Research Conference
Buenos Aires, Argentina, September 21st to 23rd, 2011
Objective
Human brucellosis in Ecuador is underreported and based only on passive surveillance. Since 2009, brucellosis was discarded from the list of notifiable diseases in the country. Until now, the human picture has no yet been determined. Between 2006 and 2008, a cross-sectional study was set up in Ecuador to estimate the prevalence and to identify possible risk factors involved in human brucellosis.
Methods and study area
Blood samples of people (n=3,733) living in five provinces in the north eastern region of Ecuador were tested for antibodies against Brucella spp (see Map, in brown). The results of the assays, i.e. the Rose Bengal Fast Agglutination Test (RB), the Wright’s Slow Agglutination Test in presence of EDTA (SAT-EDTA) and the indirect Enzyme Linked Immunosorbent Assay (iELISA) were analyzed. The causative agent was isolated by the automatic BACTEC system. 
Results
In total, 70 persons (i.e % with 95% Confidence Interval [C.I.] 1.48 – 2.38%) reacted positive to at least one diagnostic test. Seroprevalence detected by each of the assays was: RB 1.63% (C.I – 2.09), SAT-EDTA 0.56% (C.I – 0.87) and iELISA 1.55% (C.I – 2.00). Only 0.48% (18/3733) (C.I – 0.78) yielded a positive reaction by all three tests. Based on multivariate analysis, the following significant risk factors were identified: consumption of raw or boiled milk OR (odds ratio) =3.94 (C.I – 9.31), age between 16 and 45 years OR =3.89 (C.I – 12.74), professional activity directly related to a slaughterhouse OR=3.14 (C.I – 5.28), consumption of bovine foetus or placentas OR=2.10 (C.I – 4.33) and living in the Sierra region OR= 2.07 (C.I – 3.71). Seroprevalence in male (2.22% C.I – 2.96) and female (1.40% C.I. 0.9 – 2.15) demonstrated that gender has no influence in seropositivity.
Blood cultures from 22 highly seropositives resulted in three successful isolations, typified as Brucella abortus biotype 4.
Results of diagnostic assays RB
SAT
iELISA
Number -
3663 + 7 2 11 31 1 18
Total
3733
RB: Rose Bengal; SAT-EDTA: Serum Agglutination Test;
iELISA: Enzyme Linked Immunosorbent Assay
In vitro characteristics of the isolations
Conclusion
Although Ecuador has been considered by some authors as non–endemic for human brucellosis, our results demonstrate the opposite. This discrepancy may be due to deficiency in reporting positive cases and consequently a lack of an active epidemio-surveillance in supposedly brucellosis-free countries. The evidence presented in the present study is of high importance to enhance awareness and understanding of the disease, and to develop a structured prevention-control programme at nationwide level.
*= hemoculture; ** = control Brucella abortus biotype 2; *** = control Brucella abortus biotype 9
SEPTIEMBRE 2011
1 Centro Internacional de Zoonosis (CIZ), Universidad Central del Ecuador, Quito - Ecuador.
2 Institute of Tropical Medicine, Department of Animal Health, Antwerp - Belgium.
3 Department of Bacteriology and Immunology,
Veterinary and Agrochemical Reserch Centre, Brussels - Belgium.
4 University of Liège, Faculty of Veterinary Medicine,
Department of Infections and Parasitic Diseases,Liège - Belgium.