According to published literatures, it has been reported that rice allergy may cause severe allergic reactions in individuals, leading to respiratory (asthma, AR, rhino-conjunctivitis), GI (vomiting, abdominal pain, diarrhea), skin (atopic dermatitis, angioedema, urticaria), and systemic symptoms (anaphylaxis) (2, 7, 11).
Oral allergy symptoms and Anaphylaxis
Ingestion of rice or inhalation of rice dust/flour may induce IgE-mediated food allergy symptoms, such as OAS or even anaphylaxis (10). This has been documented in several case reports, mentioned below.
In a case series involving three LTP-allergic patients (25-, 30-, and 50-year-old patients), anaphylaxis induced by rice was reported. All the three cases were presented with dyspnea, generalized urticaria or angioedema on consumption of risotto (cooked rice and mushrooms) and/or rice along with chicory. The results showed positive SPT for commercial rice extract with high rice sIgE (11).
A case of repeated anaphylactic episode, following oral ingestion of rice with symptoms, such as angioedema, pruritis, generalized urticaria, bronchospasm, and dysphagia was reported. The results revealed that IgE reactivity was confirmed (detected by SPT) for various rice extracts (both raw rice and cooked boiled rice) (8).
Gastrointestinal reactions, such as pain in the abdomen, nausea, vomiting and diarrhea on consumption of rice was reported in a 9-year-old girl. The SPT and prick-prick tests showed a noticeable wheal and flare response with rice. Furthermore, a double-blind, placebo-controlled, food challenge test performed on the patient reported GI symptoms within 10 mins of eating rice; however, it was observed that she didn’t show any allergic reaction while consuming other cereals (9).
Rice flour-induced anaphylaxis was reported in a 6-month-old girl who was admitted in the hospital thrice as a result of immediate onset of respiratory as well as GI symptoms, pale skin, and decreased responsiveness (20). Anaphylaxis has also been reported due to inhalation of rice proteins in a 11-year-old-boy with atopic dermatitis (15).
Allergic rhinitis, rhino-conjunctivitis, and asthma
Inhalation of rice dust/pollen may induce AR, and this could be considered as one of the factors for the development of asthma in individuals (19).
It has been reported that allergy to rice pollens may induce these respiratory symptoms among rice farmers and people living near rice farms during the flowering season of rice plants (4). A cross-sectional study conducted among 464 rice farmers (mean age 48.3± 15.2 years) in California (USA) reported AR (25.7%), persistent wheeze (8.8%), asthma and severe cough (7.1% each), and bronchitis (6.3%), due to burning of rice stubble in the agricultural fields (21).
In a study conducted in Taiwan, 9.3% of asthmatic children showed positive response to rice pollen extract (n=312), and it was reported that sensitization to rice pollen might be one of the important factors for eliciting IgE-specific responses in the patients (2, 22).
In a case series of four patients, it was reported that inhalation of raw rice (while throwing rice in wedding ceremony) may have led to respiratory-allergic symptoms (rhino-conjunctivitis and asthma) (23, 24) (23).
A case of AR was identified in a 31-year-old male who worked in a grain industry and showed a prior history of runny nose, blockage, sneezing and itchy/burning eyes at work, while being exposed to rice powder. His symptoms aggravated at workplace. The SPT was found positive for rice extracts, the serum-IgE level for rice was reported high, and the nasal provocation test with rice extract showed development of AR. The findings indicated that inhalation of rice flour at workplace may have led to AR (19).
Atopic Dermatitis
Allergic reaction induced by rice could be IgE mediated in cases of AD and bronchial asthma (10). Few studies have been reported, which suggest that exacerbation of AD may be caused by rice (7).
In a study conducted in Japan among 1006 patients with AD, it was found that rice may be associated with the severity of AD. Furthermore, excluding rice in the diet of 25 severe AD patients showed good improvement of AD in 9 patients, moderate improvement in 10 patients, and neither aggravation nor any effect in 6 patients (25)
A case of a 3-year-old boy (with AD since the age of 3 months) was reported, who showed worsening of AD symptoms (skin eruptions and rashes) after coming in contact with rice dust (3).
Urticaria and Angioedema
Direct touching/sorting of raw rice or the water used for washing rice may lead to contact urticaria in certain individuals (10).
Two case reports have been identified where handling of raw rice led to contact urticaria in hand. The first case was of a 27-year-old housewife who showed positive SPT with flour extract, positive rub test and challenge test with raw rice, and high rice-specific IgE in serum. (24). In the second case of a 17-year-old female, SPT with rice revealed urticaria suggesting raw rice could be the cause of cutaneous reaction in the patient (26). Furthermore, development of contact urticaria (erythema and itching) after washing rice in water was reported in a 30-year-old male who showed positive SPT with rice allergen, and avoidance of contact with water used for washing rice improved the skin conditions (27).
Furthermore, occurrence of urticaria and angioedema after inhalation of raw rice has rarely been reported. This was evident in a 9-year old girl who developed urticaria-angioedema after inhaling raw rice (9).
Urticaria and angioedema of the eyelids, tongue, and lips as a result of consumption of rice has also been reported in a case study of a 33-year-old German patient (8).
Other diseases
Rice millers’ syndrome
It has been reported that the rice millers’ syndrome might occur as a result of exposure to rice husk powder. The clinical manifestations may include irritation of eyes, skin, and respiratory tract; allergic reactions like nasal discharge, chest tightness, asthma, and high eosinophil counts, along with pulmonary infiltrates, which might represent early silicosis or hypersensitivity pneumonitis. This was evident in a Malaysian study conducted on 122 rice-mill workers (28).