Identification of crab proteins that elicit IgE reactivity in snow crab-processing workers.

BACKGROUND: The expanding snow crab-processing industry has resulted in increased numbers of workers at risk of occupational allergy. OBJECTIVE: Our study is to identify relevant allergenic proteins in cooked snow crab meat (CM) and crab water (CW) used for cooking for improved remediation, diagnosis, and treatment. METHODS: Extracts were prepared from CM extracts, CW extracts, and an air-filter collection near the crab cooker. Of the 207 workers, 24 with the highest IgE antibody reactivity to CM and CW extracts, as determined by using RASTs, were tested for reactivity to nitrocellulose membranes containing CM and CW proteins separated with SDS-PAGE. A 3-serum pool was similarly incubated against nitrocellulose-bound proteins from air samples collected near the crab cooker. RESULTS: Of the 207 sera tested, 27 and 39 sera exhibited positive IgE antibody reactivity (>or=2%) to CM and CW extracts, respectively. Twenty-two of 24 sera with the highest RAST activity (>or=3.5% binding) demonstrated IgE binding to multiple proteins (13.6-50 kd). A majority of the sera reacted to 4 proteins: 79% and 71% to a 34.0-kd protein, 79% and 42% to a 25-kd protein, 67% and 71% to an 18.5-kd protein, and 75% to a 14.4-kd protein in both CM and CW extracts, respectively. The pool of IgE-positive sera blotted against the air-filter extract reacted to 14.4-, 18.5-, 34.0-, 43.2-, and 50-kd proteins present in both crab extracts. CONCLUSION: Four major IgE-reactive proteins were identified in CM extracts, CW extracts, and air-filter eluate. Analysis of any potential association of protein reactivity with disease suggested crab proteins at 34.0 and 14.4 kd might be more relevant.

Gender and snow crab occupational asthma in Newfoundland and Labrador, Canada.

Fish and shellfish processing employs many thousands of people globally, with shellfish processing becoming more important in recent years. Shellfish processing is associated with multiple occupational health and safety (OHS) risks. Snow crab occupational asthma (OA) is work-related asthma associated with processing snow crab. We present a gender analysis of findings from a 3-year multifaceted study of snow crab OA in Newfoundland and Labrador, Canada. The study was carried out in four snow crab processing communities between 2001 and 2004. An anonymous survey questionnaire on knowledge, beliefs, and concerns related to processing snow crab administered to 158 workers attending community meetings at the start of the research found that women were significantly more likely than men to associate certain health problems, especially chest tightness, difficulty breathing, and cough, with crab processing (P<0.001). Worker health assessments carried out with 215 processing workers (187 current/28 former; 120 female/95 male) found that female participants were more likely to be diagnosed as almost certain/highly probable snow crab OA and allergy (P=0.001) and to be sensitized to snow crab (P=0.01) than male participants. Work histories from the health assessments were used to classify processing jobs as male or female. Allergen sampling (211 allergen samples: 115 area, 96 personal breathing zone) indicated that the plant areas where these male jobs were concentrated were associated with lower levels of aerosolized crab allergens (the agents responsible for OA to snow crab) than areas associated with female jobs. This difference was statistically significant in the two plants with poor ventilation (p<0.001 and P=0.017 for these plants). A gender analysis of work history data showed that female health assessment participants were likely to have worked longer processing snow crab than males (5 years versus 3.5 years, respectively). Cross-referencing of work history results with allergen sampling data for male and female job areas showed a gender difference in median cumulative exposures (duration of exposure x level of exposures) for health assessment participants. Health assessment participants with estimated higher median cumulative exposures were more likely to receive a diagnosis of almost certain/highly probable OA and allergy. Semistructured interviews with 27 health assessment participants (24 female/ 3 male) with a diagnosis of almost certain/highly probable or possible snow crab OA indicated that these workers can experience substantial quality of life impacts while working and that they seek to reduce the economic impact of their illness by remaining at their jobs as long as possible. Indications of selection bias and other study limitations point to the need for more research exploring the relationship between the gender division of labor and knowledge, beliefs, and concerns about snow crab processing, as well as gender differences in prevalence, quality of life, and socioeconomic impact.

Prevalence of crab asthma in crab plant workers in Newfoundland and Labrador.

OBJECTIVES: The aim of the study was to determine the prevalence of snow crab sensitisation and occupational asthma. STUDY DESIGN: Prevalence study of symptoms, pulmonary function testing and allergy testing to crab was conducted in four crab plants of different design in Newfoundland and Labrador, Canada. METHODS: Plants workers in four crab plants were interviewed and offered skin testing, RAST, pulmonary function testing and peak flow monitoring before and during crab processing. RESULTS: 38% (n=78) had atopy. 18% (n=39) had certain or highly probable crab asthma. The prevalence of sensitisation in different crab plants varied from 50% (n=19) to 15% (n=16) and the prevalence of certain or highly probable crab asthma varied from 50% (n=19) to 9% (n=3). CONCLUSION: Crab asthma and sensitisation to snow crab is a major health problem for snow crab plant workers in Newfoundland and Labrador.

Knowledge, attitudes and beliefs regarding crab asthma in four communities of Newfoundlad and Labrador.

OBJECTIVES: This study was conducted to learn from snow crab plants workers and others involved in the industry their knowledge and beliefs of health issues and potential solutions. STUDY DESIGN: This is a survey in four communities with different crab plant designs in Newfoundland and Labrador, Canada. METHODS: At the start of a meeting to discuss crab asthma participants were requested to complete the questionnaire. RESULTS: 65% of 196 participants believed there were health problems associated with crab plants. 85% have heard of crab asthma. Almost 80% identified correctly the major symptoms of crab asthma as difficulty breathing, chest tightness and cough. Only 74% of workers did not know that workers with crab asthma were eligible for workers' compensation. 55% of those surveyed had heard of crab asthma from crab plant workers and only 26% from their doctor or nurse. If they had breathing problems, 73% would see their local doctor, and 51% a specialist and 51% their nurse. CONCLUSION: The majority of participants believed that there were health problems associated with crab plants. The majority of crab plant workers could identify symptoms of crab asthma correctly. Many do not know that those with crab asthma can obtain workers' compensation. Most of them learn of crab asthma from other workers but would seek treatment from their doctor.