Secondary prevention of allergic symptoms in a dairy farmer by use of a milking robot
© Korinth et al; licensee BioMed Central Ltd. 2005
Received: 26 August 2004
Accepted: 22 June 2005
Published: 22 June 2005
Animal-derived allergens include lipocalins which play an increasing role in occupational respiratory sensitizations. The prevention of sensitization in stock farming is often difficult due to intense exposure, with traditional milking still requiring close animal contact. Complete avoidance of allergen exposure is only possible if stock farming is abandoned. This is, however, often not feasible in small dairy plants because of the resulting loss of income.
In a 37-year-old female farmer daily asthmatic complaints appeared, associated with cow dust-derived allergen exposure by milking with a conventional device. Respiratory symptoms increased during a period of 12 years. Allergic bronchial asthma was diagnosed, caused by sensitization against cow dust-derived allergens, as demonstrated by positive skin prick test and by detection of IgE antibodies. In a separate specific inhalation challenge test using a 10% extract of cow dust-derived allergens a 330% increase of airway resistance was detected. To enable further dairy farming, a milking robot was installed in 1999, i.e., an automatic milking system. The novel milking technique reduced the daily exposure from over 2 hours to approximately 10 min. The clinical course after the installation of the milking robot was favourable, with less frequent allergic and asthmatic symptoms. Furthermore, asthma medication could be reduced. Improvement was noted also in terms of lung-function and decreased total serum IgE.
The case presented and the evidence from the literature indicates that the strategy of exposure minimization to allergens at workplaces can be an effective alternative to total elimination. In farmers with cow dust allergy a milking robot is an appropriate technical measure to minimize allergen-exposure.
Allergic asthma ranks in Germany among frequent occurred occupational diseases. Cow hair allergy in Finland is one of the most frequent reasons for the development of occupational asthma , but epidemiologically in Germany still insufficiently explored. The prevalence of respiratory complaints in Finnish farmers with cow husbandry is 27% for rhinitis respectively 12% for asthma in consequence of occupational exposure [2, 3]. Until now there is only limited insight into the risk factors with regard to this disease. The prevention of sensitization in stock farming to cow hair and epithelial allergens including lipocalins is often difficult due to intense exposure, with traditional milking still requiring close animal contact.
The German Professionals insurance laws require a complete elimination of allergens for the recognition of an allergic airway disease as a compensable occupational disease. Complete avoidance of occupational exposure of cow hair allergens is only possible if stock farming is abandoned. This is, however, often not feasible in small dairy plants because of the resulting loss of income.
In the present case report we discuss the efficiency of the strategy of exposure minimization to allergens by the use of a milking robot, i.e., an automatic milking system (AMS) as an alternative measure to total elimination of allergens for the prevention of occupational asthma caused by cow hair allergy.
Case presentation and discussion
A 37-year-old female farmer reported to suffer from daily asthmatic complaints by milking of cows with a conventional device. Exposure associated respiratory symptoms increased continuously during a period of 12 years. Allergic bronchial asthma, caused by sensitization against cow dust-derived allergens, was diagnosed by a positive skin prick test (Bencard®) and by the detection of IgE antibodies against Bos d 2 at 74.9 kIU/l (Pharmacia, UniCAP®). Moreover, nonspecific bronchial hyperresponsiveness was verified by a positive histamine inhalation challenge test. The diagnosis of occupational asthma was confirmed by a separate specific inhalation challenge test using a 10% extract of cow hair allergens which led to a 330% increase of airway resistance (Raw).
The German Professionals insurance laws require complete elimination of allergen exposures for the compensation of occupational allergic asthma as occupational disease . Legal consequence would usually be to abandon dairy farming. However, in our case presented, dairy farming substantially contributed to family-income and the compensation offered would be insufficient for subsistence. Hyposensitization is the most effective measure in the prevention of allergic symptoms in patients with asthma. In that farmer the hyposensitization was not feasible due to permanent exposure to allergens. This farmer did not wear a helmet during the milking process because of claustrophobic panic attacks (fear of suffocation). Moreover an immunotherapy with recombinant lipocalins is currently not available.
Respirator helmets have been predominantly used as effective measures for prevention of the inhalation of fumes and dusts . Investigations about the effectiveness of respirator helmets against high-molecular allergens to prevent allergic asthma are rare. Taivainen et al. (1998) demonstrated that due to the use of a dust respirator helmet with a P2-class filter, dairy farmers with occupational asthma induced by cow dander showed less rhinitic symptoms and an improved peak flow rate . However, workers using respirator helmets were not prevented against a progressive behavior of occupational asthma [7, 8]. Thus it is to doubt whether respirator helmets are efficient in farmers with occupational asthma to provide a complete protection against allergens .
Parameters influenced by automatic milking system (AMS)
Power of parameter
Influence of AMS
Daily exposure period
Drop of more than 2 hours to approx. 10 min. (> 90%)
Increasing space to cow
• No commitment to fixed milking times
• Free working plan
Quality of life
More time available for other activities
After installation of the milking robot the farmer reported significantly less frequent allergic and asthmatic symptoms. Asthma medication was reduced and required only once daily in the evening. Improvement was noted also in terms of lung-function and decreased total serum IgE: serum IgE decreased from 1332 IU/ml before milking robot installation to 572 and 474 IU/ml two and three years after installation, respectively. FEV1 improved by 20% and vital capacity by 11%, comparing values one year before with two years after installation. A CAP-RAST score "5" versus Bos d 2 was determined after the intervention. Preceding EAST-Test results vs. Bos d 2 were not suitable for comparison.
Examples for successful measures of exposure minimization at workplaces in reducing of sensitizations
Measure of exposure minimization
Replacement of powdered gloves through powder-free gloves
Edelstam et al. 2002, Tarlo et al. 1994
Animal research laboratories
Allergens to laboratory animals
Technical improvement of housing cabinets for animals
Thulin et al. 2002
Installation of a closed system in the production of epoxy resin
Drexler et al. 1999
The case presented and the evidence obtained from the literature indicates that the strategy of exposure minimization to allergens at workplaces can be an effective alternative to total elimination, which may not be feasible for economical reasons. In farmers with cow dust allergy a milking robot is an appropriate technical measure to minimize allergen-exposure particularly with regard to the reduced animal contact. Independently from this, such milking robots also increasingly used to enhance productivity (usually in herds comprising more than 50 animals). The efficacy of milking robots in terms of primary and secondary prevention should be evaluated also epidemiologically in a suitable cohort study, preferably in countries with intensive dairy farming.
List of abbreviation
Automatic milking system
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