The number of immigrants from less-developed to well-developed countries is growing and has influenced the epidemiology of infectious diseases, such as tuberculosis, malaria and strongyloidiasis in the developed world [Reference Gushulak and MacPherson1]. Brucellosis is a worldwide zoonosis that is controlled in most developed countries. Humans may become infected by ingestion of unpasterurized cheese or milk, by direct transmission through contact with infected animals or by handling specimens containing Brucella spp. in laboratory workers. The incidence of human brucellosis in Spain decreased from 22·72 cases/100 000 in 1984 to 1·5/100 000 in 2004 [Reference Sanchez Serrano2]. We have no knowledge of a previous brucellosis outbreak in the immigrant population in Spain. This report describes a brucellosis outbreak among Moroccan residents in the city of Elche, on the Mediterranean coast of Spain.

The Hospital General Universitario de Elche is an urban, public, university-affiliated hospital with 450 beds that provides health care for a population of the Baix Vinalopo Department of Health (BVDH) (267 954 inhabitants; 9·6% immigrants in 2006) on the Mediterranean coast of Spain. The incidence of brucellosis in the province is lower than in other Spanish provinces with rates of 0·71 cases/100 000 inhabitants in 2003 and 2004 and 0 cases in 2005.

On 22 July 2006, a 41-year-old Moroccan male (case 1) was admitted with sacral pressure sore and fever that had pesisted for 7 days. Unexpectedly Brucella spp. grew on blood cultures within 48 h (BACTEC 9240; Becton Dickinson, Heidelberg, Germany) [Reference Bannatyne, Jackson and Menish3] (Table).

Table. Epidemiological, clinical features and outcome of 11 patients with brucellosis

F, female; M, male; n.a., not available; n.d., not done; mos, months; AST, aspartate aminotransferase; ALT, alanine aminotransferase; STA, standard tube agglutination.

The second case (case 2) was a 14-year-old Moroccan male who came to the Emergency Department on 27 July. The patient had suffered from symptoms of fever, chills, sweating and myalgias for 17 days. Brucella spp. grew on blood cultures within 3 days. The boy was a relative of case 1 and used to eat at his house. Cases 1 and 2 are referred to as ‘family A’ (see Table).

On 11 September 2006 another two Moroccan males from a different family (cases 3 and 4) visited the Emergency Department complaining of fever. Case 3 was aged 29 years and had fever, headache, sweating, chills, and loss of weight over the previous 30 days. Case 4 was aged 21 years, a nephew of case 3, and complained of pain and swelling of the left testicle for 10 days. Both patients were positive by the Rose Bengal test (Brucelloslide test; bioMérieux, Marcy-l'Etoile, France) [4], and Brucella spp. grew from blood cultures. These patients did not know the first two patients. They also stated that they occasionally purchased fresh cows' and goats' milk from a local farm and drank it unpasteurized.

On 2 October 2006, an 18-year-old female, the sister of case 4, presented with a 3-day history of fever, nausea, vomiting and headache. She had a previous episode of fever in early September 2006 that disappeared after a course of empiric antibiotics prescribed by her doctor. The Rose Bengal test was positive and Brucella spp. grew on blood cultures. Cerebrospinal fluid showed the following results: leukocytes 346/ml (60% lymphocytes); proteins 69·5 mg/d; glucose 100 mg/dl; the Rose Bengal test was positive and Brucella was not isolated. Cases 3–5 are referred to as ‘family B’.

The public health staff of the BVDH visited the farm where patients of family B had bought unpasteurized milk. The farm had stopped selling milk from goats in July 2006 because several animals on the farm were found to have brucellosis. Moreover, two workers on this family farm, which was in a municipality belonging to a different Department of Health, had been diagnosed with occupational brucellosis (by serology) in July 2006. The two workers were sons of the owner of the farm and use to help with calving (cases 6 and 7). Members of family A also had purchased unpasteurized milk from the farm.

The public health staff of the BVDH contacted all the house relatives of case 2 (family A) and cases 3–5 (family B) in order to perform a Brucella serology test. Six asymptomic members of family A were studied. A sister-in-law of case 2 gave a positive agglutination test titre (case 8) (Table), whereas her two sons (a 2-year-old boy and a baby), and two brothers and a sister of case 2, gave negative results. The attack rate in family A was 37·5%.

We studied four members of family B. Two brothers of cases 4 and 5 who were asymptomatic had standard and Coombs tube agglutination test titres (Brucella abortus agglutinations; BioSystems, Barcelona, Spain) of ⩾1/2560 [4] (cases 9 and 10). Finally, the mother complained of pain in the right hand with no fever. On physical examination, she had mild arthritis of the right carpal joint and standard and Coombs tube agglutination test titres of ⩾1/1280 (case 11). The father of cases 4, 5, 7 and 8 had no symptoms and the Rose Bengal and standard tube agglutination tests were negative. The attack rate in family B was 85·7%.

No additional cases of brucellosis were found from June to December 2006, after a search of hospital records and infectious diseases outpatient clinic files, looking for undiagnosed pyrexia of unknown origin (code 780.6 for CD-9-CM). All isolates were identified as Brucella melitensis biovar 3 according to the National Brucellosis Reference Laboratory (Valladolid, Spain).

In Spain outbreaks [Reference Méndez Martínez5, Reference Castell Monsalve6] associated with unpasteurized raw goats' cheese have been described. The last one published occurred in Andalusia in 2002 and involved 11 patients [Reference Méndez Martínez5]. The outbreak described in this report was unique because it involved two immigrant Moroccan families and happened in an area with a very low incidence of brucellosis. The outbreak was due to unpasteurized raw milk from goats, and it was possible to identify two main factors: the illegal sale of raw milk by certain dairy farmers and the belief of these Moroccan families in the beneficial effects of raw milk consumption.

This outbreak alerted us to the fact that it is necessary to reinforce both educative and focused public health measures for the prevention of infectious diseases among the immigrant population. In Spain, previous outbreaks of other diseases, including tuberculosis [Reference Valles7] and rubella [Reference Torner8, 9], have been described in immigrant populations. As a result of the outbreak described here, several meetings were held with the different immigrant associations in the Health Authority to explain to them that the consumption of unpasterurized raw milk and cheese is a health hazard. Closer surveillance to avoid illegal sale of milk has also been implemented.