D2.144 - Occupational Asthma due to garlic powder: a case report

Despite occupational asthma (OA) is known to be associated with various spices, no studies have been published in the past 30 years on the diagnostic approach to OA due to garlic.

Here we present a case of OA induced by garlic. Written informed consent was obtained from the patient for the publication of the case.

A 34-year-old male worker, with no prior history of respiratory diseases, had been employed since 2021 as a quality control worker in a company producing food spices. In July 2022, following an accidental exposure of his right eye to a spice preparation, he developed productive cough, shortness of breath, and wheezing, which occurred and worsened during work activities. The respiratory symptoms disappeared on weekends and during holidays.

In January 2024, a skin prick test revealed sensitization to common aeroallergens (birch, hazel, olive pollen, and dust mites) and food allergens, with a strong reaction to both fresh and dehydrated garlic. SIgE were positive for garlic (1.09 kU/L).

In December 2024, the patient underwent a specific inhalation challenge at the Occupational Medicine Unit of Padua University Hospital to confirm OA.

Baseline pulmonary function tests (PFTs) performed on day 1 showed normal lung volumes and carbon monoxide diffusion capacity (DLCO), while the fractional exhaled nitric oxide (FeNO) values were mildly elevated (36 ppb). On day 2 (control day), the patient inhaled an inert substance (lactose powder), showing no FEV₁ variation >10% during the 7-hours monitoring. At the end of the test, lung function, non-specific bronchial reactivity, and FeNO concentration (24 ppb) were within normal limits.

On day 3, at time 0, the patient inhaled a mixture of lactose and garlic with a 1% garlic concentration for the first 30 minutes and then a mixture of lactose and garlic with a 5% garlic. After the test began, he developed rhino conjunctival symptoms and progressive cough. After 38 minutes of exposure, FEV₁ decreased by 20% from baseline (baseline FEV₁: 3820 mL; post-exposure FEV₁: 3070 mL) (figure 1).

On day 4, PFTs showed a marked increase in FeNO concentration (63 ppb) and non-specific bronchial hyperreactivity (methacholine PD20: 264 µg).

Based on the SIC results, a diagnosis of garlic-induced OA was done, thus confirming this type of test as the gold standard for the diagnosis of OA even in the presence of high molecular weight inducers.