Mohamed F. Jeebhay

Occupational seafood allergy: a review

BACKGROUND Recent years have seen increased levels of production and consumption of seafood, leading to more frequent reporting of allergic reactions in occupational and domestic settings. This review focuses on occupational allergy in the fishing and seafood processing industry. REVIEW Workers involved in either manual or automated processing of crabs, prawns, mussels, fish, and fishmeal production are commonly exposed to various constituents of seafood. Aerosolisation of seafood and cooking fluid during processing are potential occupational situations that could result in sensitisation through inhalation. There is great variability of aerosol exposure within and among various jobs with reported allergen concentrations ranging from 0.001 to 5.061(μg/m3). Occupational dermal exposure occurs as a result of unprotected handling of seafood and its byproducts. Occupational allergies have been reported in workers exposed to arthropods (crustaceans), molluscs, pisces (bony fish) and other agents derived from seafood. The prevalence of occupational asthma ranges from 7% to 36%, and for occupational protein contact dermatitis, from 3% to 11%. These health outcomes are mainly due to high molecular weight proteins in seafood causing an IgE mediated response. Cross reactivity between various species within a major seafood grouping also occurs. Limited evidence from dose-response relations indicate that development of symptoms is related to duration or intensity of exposure. The evidence for atopy as a risk factor for occupational sensitisation and asthma is supportive, whereas evidence for cigarette smoking is limited. Disruption of the intact skin barrier seems to be an important added risk factor for occupational protein contact dermatitis. CONCLUSION The range of allergic disease associated with occupational exposure to crab is well characterised, whereas for other seafood agents the evidence is somewhat limited. There is a need for further epidemiological studies to better characterise this risk. More detailed characterisation of specific protein antigens in aerosols and associated establishment of dose-response relations for acute and chronic exposure to seafood; the respective roles of skin contact and inhalational exposure in allergic sensitisation and cross reactivity; and the contribution of host associated factors in the development of occupational seafood allergies are important areas for future research.

Occupational Allergy and Asthma Among Salt Water Fish Processing Workers

BACKGROUND Fish processing is a common economic activity in Southern Africa. The aim of this study was to determine the prevalence and host determinants of allergic symptoms, allergic sensitization, bronchial hyper-responsiveness and asthma among workers processing saltwater fish. METHODS A cross-sectional study was conducted on 594 currently employed workers in two processing plants involved in pilchard canning and fishmeal processing. A modified European Community Respiratory Health Survey (ECRHS) questionnaire was used. Skin prick tests (SPT) used extracts of common airborne allergens, fresh fish (pilchard, anchovy, maasbanker, mackerel, red eye) and fishmeal. Spirometry and methacholine challenge tests (MCTs; tidal breathing method) used ATS guidelines. RESULTS Work-related ocular-nasal symptoms (26%) were more common than asthma symptoms (16%). The prevalence of atopy was 36%, while 7% were sensitized to fish species and 26% had NSBH (PC(20) < or = 8 mg/ml or > or =12% increase in FEV(1) post-bronchodilator). The prevalence of probable occupational asthma was 1.8% and fish allergic rhino-conjunctivitis 2.6%. Women were more likely to report work-related asthma symptoms (OR = 1.94) and have NSBH (OR = 3.09), while men were more likely to be sensitized to fish (OR = 2.06) and have airway obstruction (OR = 4.17). Atopy (OR = 3.16) and current smoking (OR = 2.37), but not habitual seafood consumption were associated with sensitization to fish. CONCLUSIONS Based on comparison with previous published studies, the prevalence of occupational asthma to salt water fish is lower than due to shellfish. The gendered distribution of work and exposures in fish processing operations together with atopy and cigarette smoking are important determinants of occupational allergy and asthma.

Seafood workers and respiratory disease: an update.

Purpose of reviewThis review focuses on seafood workers engaged in harvesting, processing and food preparation. These groups are increasingly at risk of developing occupational allergy and respiratory disease as a result of seafood handling and processing activities. This review provides an update of a previous review conducted a decade ago. Recent findingsExposure characterization studies have demonstrated that aerosolization of seafood (muscle, visceral organs, skin/mucin) during canning and fishmeal operations result in highly variable levels of airborne particulate (0.001–11.293 mg/m3) and allergens (0.001–75.748 ug/m3). Occupational asthma is more commonly associated with shellfish (4–36%) than with bony fish (2–8%). Other seafood-associated biological (Anisakis) and chemical agents (protease enzymes, toxins and preservatives) have also been implicated. Atopy, smoking and level of exposure to allergens are significant risk factors for sensitization and the development of occupational asthma. Molecular studies of the allergens suggest that aside from tropomyosin and parvalbumin, other as yet uncharacterized allergens are important. SummaryFuture research needs to focus on detailed characterization of allergens in order to standardize exposure assessment techniques, which are key to assessing the impact of interventions. The clinical relevance of agents such as serine proteases and endotoxins in causing asthma through nonallergic mechanisms needs further epidemiological investigation.

Characterisation of purified parvalbumin from five fish species and nucleotide sequencing of this major allergen from Pacific pilchard, Sardinops sagax

IgE-mediated allergic reaction to seafood is a common cause of food allergy including anaphylactic reactions. Parvalbumin, the major fish allergen, has been shown to display IgE cross-reactivity among fish species consumed predominantly in Europe and the Far East. However, cross-reactivity studies of parvalbumin from fish species widely consumed in the Southern hemisphere are limited as is data relating to immunological and molecular characterisation. In this study, antigenic cross-reactivity and the presence of oligomers and isomers of parvalbumin from five highly consumed fish species in Southern Africa were assessed by immunoblotting using purified parvalbumin and crude fish extracts. Pilchard (Sardinops sagax) parvalbumin was found to display the strongest IgE reactivity among 10 fish-allergic consumers. The cDNA sequence of the beta-form of pilchard parvalbumin was determined and designated Sar sa 1.0101 (accession number FM177701 EMBL/GenBank/DDBJ databases). Oligomeric forms of parvalbumin were observed in all fish species using a monoclonal anti-parvalbumin antibody and subjects sera. Isoforms varied between approximately 10-13 kDa. A highly cross-reactive allergenic isoform of parvalbumin was identified and sequenced, providing a successful primary step towards the generation of a recombinant form that could be used for diagnostic and potential therapeutic use in allergic individuals.

The utility of biological monitoring for manganese in ferroalloy smelter workers in South Africa.

Five hundred and nine workers at a manganese (Mn) smelting works comprising eight production facilities and 67 external controls were studied cross-sectionally. Exposure measures from personal sampling included inhalable dust, cumulative exposure indices (CEI) and average intensity (INT = CEI/years exposed) calculated for the current job at the smelter and also across all jobs held by subjects. Biological exposure was measured by Mn in the blood (MnB) and urine (MnU) and biological effect was measured by serum prolactin. Average lifetime exposure intensity across all jobs ranged from near 0 (0.06 microg/m3) for unexposed external referents to 5 mg/m3. Atmospheric exposures and MnB and MnU distributions were consistent with published data for both unexposed and smelter workers. Associations between biological exposures and groups defined by atmospheric exposures in the current job were substantial for MnB, less so for MnU and absent for serum prolactin. Random sampling of MnB measurements representative of a group of workers with more than 1-2 years of service in the same job and notionally homogenous exposure conditions could serve as a cross-sectional predictor of atmospheric Mn exposure in the current job, as well as for surveillance of Mn exposure trends over time. Correlations at the individual level were only modest for MnB (33% of the variance in log atmospheric Mn intensity in the current job was explained by log MnB), much worse for MnU (only 7%). However, a receiver operating characteristic (ROC) analysis was performed which showed that it is possible to use a MnB cut-off of 10 microg/l (the 95th percentile in the unexposed) to good effect as a screening tool to discriminate between individual exposures exceeding and falling below a relatively strict atmospheric Mn exposure threshold at the ACGIH threshold limit value (TLV) of 0.2 mg/m3. MnU has no utility as a measure of biological exposure nor does serum prolactin as a measure of biological effect.

World at work: Fish processing workers

Spotlight on a growth industry The fishing and fish processing industry has experienced tremendous growth in recent years. In 1990 the Food and Agriculture Organisation (FAO) estimated that the number of people engaged in fishing, aquaculture, and related activities worldwide doubled to 28.5 million from 1970.1 Among these workers 52% worked aboard fishing trawlers, 32% were involved in aquaculture production (marine and freshwater), and 16% worked inland as capture fishers or in other land based activities such as processing. Ninety five per cent of these workers were from developing countries, producing 58% of the 98 million tons of world fish. Increased levels of production and processing of seafood have led and continue to lead to more frequent reporting of occupational health problems such as asthma among fish processing workers.2 These occupational health problems result in increased incapacity and absenteeism among affected workers, with women more affected as a result of differences in physical exposures and psychosocial work environments.3,4 The fishing industry in South Africa employs approximately 30 000 workers in direct employment in more than 100 workplaces and 60 000 workers in related jobs, supplying food for the entire Southern African sub-region. Labour in this industry tends to be divided along gender lines, with men almost exclusively going out to sea to catch the fish and women doing the majority of on-land processing. A large proportion (62%) of the workforce in fish processing plants is female and at least one third of the workforce is employed on a seasonal basis by the industry. In 1999, the total harvest of seafood amounted to 571 924 tons, among which bony fish such as anchovy, hake, and pilchard are the most common seafood processed. This was confirmed in a recent postal survey in which 76% of all seafood processing …

Occupational allergy in laboratory workers caused by the African migratory grasshopper Locusta migratoria

Background:  Recent reports of fatal asthma cases associated with swarms of locusts affecting African countries have highlighted the importance of this insect in causing asthma morbidity and mortality. However, only limited information is available about the allergic health outcomes such as asthma and its determinants in exposed individuals. In this study, workers exposed to the African migratory locust Locusta migratoria were evaluated for allergic health outcomes as well as the nature of the offending allergens.

Detection of Fish Antigens Aerosolized during Fish Processing Using Newly Developed Immunoassays

Background: Aerosolization of fish proteins during seafood processing has been identified as a potential route for allergic sensitization and occupational asthma among workers involved in high-risk activities. The aim of this study was to develop immunological assays for the quantification of aerosolized fish antigens in a fish-processing factory. Methods: Polyclonal antibodies to the main fish species processed in the factory (anchovy and pilchard) were generated in rabbits and compared by ELISA inhibition assay and immunoblotting. These antisera were utilized to develop ELISA assays for the detection of fish antigens. The ELISA inhibition assays were evaluated by analyzing environmental air samples collected from three areas in a fish-processing factory: pilchard canning, fish meal production and lobster processing. Results: By immunoblotting, the rabbit polyclonal antibodies demonstrated IgG antibody binding patterns comparable with IgE antibodies of fish-sensitized patients, particularly in regard to the major fish allergens parvalbumins. The sensitivity of the fish-specific ELISA assays developed was 0.5 µg/ml. The ELISA inhibition assays were able to differentiate between the two different fish species of interest but did not recognize a crustacean species. Notable differences in exposure levels to canned pilchard and anchovy antigens were demonstrated in the three different working areas of the factory, with assays having a detection limit as low as 105 ng/m3. Conclusion: These ELISA-based assays are sensitive and specific to quantify differential exposure levels to fish antigens produced during fish processing, making it possible to investigate exposure-disease response relationships among workers in this industry.

Monitoring of occupational and environmental aeroallergens - EAACI Position Paper Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution

Exposure to high molecular weight sensitizers of biological origin is an important risk factor for the development of asthma and rhinitis. Most of the causal allergens have been defined based on their reactivity with IgE antibodies, and in many cases, the molecular structure and function of the allergens have been established. Significant information on allergen levels that cause sensitization and allergic symptoms for several major environmental and occupational allergens has been reported. Monitoring of high molecular weight allergens and allergen carrier particles is an important part of the management of allergic respiratory diseases and requires standardized allergen assessment methods for occupational and environmental (indoor and outdoor) allergen exposure. The aim of this EAACI task force was to review the essential points for monitoring environmental and occupational allergen exposure including sampling strategies and methods, processing of dust samples, allergen analysis, and quantification. The paper includes a summary of different methods for sampling and allergen quantification, as well as their pros and cons for various exposure settings. Recommendations are being made for different exposure scenarios.

Differential responses to natural and recombinant allergens in a murine model of fish allergy

Aerosolized fish proteins are an important cause of allergic airway reactions in both the domestic and the occupational environment. The aim of this study was to investigate inhalant fish-induced allergy in a mouse model and compare immune responses generated by raw and heat-treated fish extracts as well as natural and recombinant forms of the major fish allergen parvalbumin. Mice were sensitized with raw or cooked pilchard extract and challenged intranasally with cooked pilchard extract, purified natural pilchard parvalbumin or recombinant carp parvalbumin (rCyp c1.01). Cooked pilchard extract predominantly sensitized mice to parvalbumin and induced specific IgG1 and IgE antibodies against both pilchard parvalbumin and rCyp c1.01, whereas additional allergens were recognized by mice sensitized with raw extract, including a 36 kDa allergen that was also recognized by fish processing workers and was identified as glyceraldehyde-3-phosphate dehydrogenase. Mice challenged with cooked extract and purified pilchard parvalbumin had increased Th2 cytokine production in mediastinal lymph node cells and splenocytes, whereas mice challenged with rCyp c1.01 did not. This study identifies a new IgE-binding protein that may be important in occupational allergy to fish and demonstrates the feasibility of testing recombinant allergens for immunotherapeutic potential in vivo.