Breeding family-owned goats and/or improper use of their milk appear to be the main risk factors for an infection which has sickened 31 people as of 15 August, according to Eurosurveillance.
A second brucellosis outbreak in Bulgaria since 2006, affects the western part of the country.
Possible source
The outbreak is most probably a consequence of unauthorised import of infected animals from an endemic country or countries, said the report.
Brucellosis caused by B. melitensis is a zoonosis that can affect every organ and system of the human body. Transmission can occur via direct contact with infected animals and/or consumption of contaminated unpasteurised milk and dairy products.
Human infections have been serologically confirmed at the National Reference Laboratory for High Medical Risk Infections (NRL HMRI).
The Bulgarian Ministry of Health updated the situation on 12 August. Further information can be found on the regional health Inspectorate of Kyustendil website (both in Bulgarian).
Three people have professions exposing them to herd animals (two shepherds and one veterinarian), 22 are animal owners/breeders and had unpasteurised dairy products from their farms, and six consumed unpasteurised local dairy products.
Patients are between 25 and 77 years-old. The most affected age group is that between 60 and 69 years-old and five are male and 26 female.
A total of 29 people are Rila town residents. Two are from outside the area but visited it or nearby less than one month prior to illness onset.
In 2006, seven cases were microbiologically confirmed, all without any epidemiological data pointing to importation.
Investigations revealed the cause was illegal importation of infected animals from a neighbouring country. By the end of 2008, 71 people had been infected and more than 600 animals were destroyed.
Raw milk stored at ambient temperature
In this outbreak, as of 15 August, 97 of 2,245 tested animals were found positive for brucellosis.
Investigation in Kyustendil revealed that raw milk stored at ambient temperature, which in July was above 30 °C, was frequently drank by local residents.
“Based on preliminary descriptive epidemiological findings, breeding of family goats and/or consumption of unboiled milk and homemade soft cheese appear as potential risk factors for transmission of the infection," said the report.
“RHI has spread information (through media and leaflets) about the dangerous nature of the disease, mechanisms of transmission, clinical manifestations and the necessary preventive measures, including the recommendation to boil milk for at least 10 min before consumption.
“Until further notice, a ban on the use of domestic milk or milk products, such as soft cheese and butter, as well as uncontrolled slaughtering of animals is imposed.
“The underestimation of the importance of applying preventive measures in local family-owned farms appears to be the main risk factor for brucellosis among Bulgarian residents.”
Source: Eurosurveillance, Volume 20, Issue 39, 1 October 2015
“A new outbreak of brucellosis in Bulgaria detected in July 2015 – preliminary report”