Allergic occupational diseases of the respiratory tract and lungs

Allergic rhinitis and bronchial asthma belong to the category of professional allergic diseases.


 * It is defined as an inflammatory disease of the nasal mucosa that occurs in response to an airborne allergen occurring in the workplace. An estimated 15–20% of the population suffers from allergic rhinitis, the proportion of occupational rhinitis cannot be estimated
 * Allergens are either common substances that are at an increased rate in the workplace (bakery flour, cereal powders…) or they are allergens specific to the given work environment (acid anhydrides in the formation of plastics…). In general, they are either high molecular weight (proteins, cereal powders, insect antigens, latex…) or low molecular weight (diisocyanates, anhydrides, rosin substances, ATB…).

Occupational exposition
Similar to asthma: flour processing (bakers, millers), grain handling (farmers), animal care, contact with disinfection (paramedics), woodworking.

Etiopatogenesis

 * Repeated contact with the allergen leads to IgE-dependent mast cell activation → vasodilation, edema, nasal obturation.
 * Inflammation mediators stimulate afferent nerve endings → itchy nose, sneezing.
 * The accumulation of inflammatory cells is characteristic.

Patology
Edematous mucosa with profuse serous exudation, the chronic form has a hyperplastic or atrophic character.

Acute

 * Itching and irritation in the nose, sneezing and watery secretions, often together with itching in the throat, eyes and ears. Asthma is often added to the symptoms.
 * These are type I reactions → symptoms appear within minutes, they go away quickly.

Chronic

 * In unrecognized and untreated recurrent acute rhinitis, it may become chronic after months to years.
 * Dominated by a feeling of a stuffy nose and thick mucus, there may be chronic changes of the conjunctiva, tearing. Sneezing and itching are usually absent.

Examination methods

 * ORL examination
 * Examination skin intradermal tests - a basic range of inhaled allergens (house dust, feathers, mites…),
 * increase in serum IgE,
 * identification of professional specific IgE antigens,
 * swab of nasal mucosa - cytological analysis (predominance of eosinophils),
 * rhinomanometry - measures the resistance of nasal passages by quantitative measurement of nasal flow and pressure,
 * active anterior rhinomanometry is usually used,
 * it is also used to assess the response to provocation tests,
 * positive rhinoprovocation test - after contact with the allergen, nasal flow decreases by at least 40% and nasal resistance increases by 60%.
 * Assessment of occupational linkage- we must demonstrate inhalation exposure to an allergenic substance in the workplace.
 * the clinical picture and the specific immunological response decide,
 * people often neglect this disease and go to the doctor only after a long time.

Diferencial diagnosis

 * In particular, rhinitis of other origins (allergic seasonal, perennial…), it is necessary to think about other pathologies in the nasal cavity.

Occupational asthma bronchiale

 * Asthma diseases caused by inhalation of harmful nox at work,
 * it is not at all different from classic asthma,
 * estimate of the share of professionalism in asthma - 2–15%, the figure is probably significantly underestimated, doctors often do not consider occupation at all.
 * Factors:
 * high molecular weight (animal and plant proteins),
 * low molecular weight (isocyanates, anhydrides, platinum salts),
 * inhalable chemicals (chlorine, ammonia),
 * pharmacologically active substances (insecticides),
 * physical factors (cold).

Occupational exposition

 * Most common allergens
 * flour (amylase) – millers, bakers, confectioners,
 * grain dust - silo workers, farmers,
 * urine and fur of laboratory and livestock - workers of research laboratories, farmers, breeders,
 * disinfectants - medical personnel,
 * natural and synthetic fibers - textile industry,
 * wood dust - saws, furniture industry,
 * proteolytic enzymes - food industry, production of washing powders,
 * rosin fumes and other welding fumes - fine mechanics, welding,
 * isocyanates, acrylic resins, paint pigments - chemical production.

Ethiopatogenesis

 * Chronic inflammatory disease, main cells involved - mast cells and eosinophils,
 * inflammation increases the reactivity of the bronchi, bronchospasm (obstruction) occurs,
 * mild asthma - there is no obstruction between attacks, but there is hyperreactivity,
 * severe asthma - obstruction present even between attacks.

Types of occuational asthma

 * Immunological occupational asthma


 * occurs in a small number of exposed,
 * after an initial asymptomatic period, by inhalation of substances previously well tolerated by the worker,
 * there is a specific immune response to the substance,
 * are caused by two types of substances, depending on the different course,
 * high molecular weight substances - induce an IgE response, it starts quickly,
 * low molecular weight substances – unknown mechanism (probably type III or IV response), delayed onset (often only after returning from work), disappears in 24 hours.


 * Asthma caused by irritation:The mechanism of origin is not entirely clear (probably plays a role in the release of neurotransmitters). It is formed after exposure to irritating substances (dust, aerosol, vapors, smoke).


 * RADS (reactive airways dysfunction syndrome):It is caused by short-term intensive exposure,


 * Reflex bronchoconstriction:Non-immunological response (without inflammation), when stimulating neuroreceptors with cold, dust, aerosols, fumes.


 * Pharmacological bronchoconstriction:It is formed by inhalation of substances that cause pharmacological bronchoconstriction, such as organophosphates.

Patology
350px| thumb | Rozdíl mezi normálním a astmatickým bronchiolem Wall remodeling occurs - thickening of the bronchiole wall (muscle hypertrophy), high epithelium, a lot of goblet cells, sometimes even squamous metaplasia, goblet cell hyperplasia occurs.

Clinical picture

 * Feeling of shortness of breath, wheezing with a maximum in the expiration (often audible at a distance - distance phenomena).
 * Coughs occur only at the workplace or in connection with work (after work).
 * Often eye complications, rhinitis…
 * Symptoms get better on weekends and holidays.

Examination methods

 * Spirometry - obstructive ventilation disorder,
 * non-specific bronchoprovocation test - acetylcholine or histamine,
 * we find non-specifically that bronchi are hyperreactive.
 * Criteria of positivity
 * decrease in FEV1 by 20%, MEF 25–75 by 30%, increase in resistance by 100%,
 * Specific inhalation bronchoprovocation tests - we administer specifically a certain substance that we suspect, either we administer commercially manufactured preparations or in an exhibition cabin (we will make the conditions of the workplace),
 * the positivity conditions are as for the non-specific test,
 * is potentially more dangerous (we administer an allergen, not the body's own substance…),
 * only by people who do not have obstruction at rest and during hospitalization.
 * Elimination test - assessment of health status after long-term exclusion from exposure.
 * Reexposition test – after the previous one, we will be involved in the process again and we will find out the state of health.
 * Skin tests, identification of specific IgE, BAL…

Differencial diagnosis
It is necessary to rule out other causes of obstruction - tumors, foreign bodies, paresis of laryngeal nerves… The basic problem is the distinction between occupational asthma and pre-existing asthma aggravated by work.

Therapy
Exclusion from exposure, corticoids, β-2-mimetics, anticholinergics, theophyllin, antiallergics.