In recent years, the prevalence of allergic diseases has been increasing. In the past 20 years, China has conducted three national epidemiological surveys on asthma in children. The results show that the average prevalence of asthma among children aged 0–14 years was 1.08% in 1990. In 2000, this number increased to 1.97%. In 2010, when 400,000 children were surveyed, the prevalence was 3.01%, up approximately 50% from 2000 [20]. Zhao Jing et al. adopted a multistage sampling method to conduct epidemiological investigations of children with AR in Beijing, Chongqing, and Guangzhou and found that the incidence rates of AR were 14.46%, 20.42%, and 7.83%, respectively. At the same time, it was found that the incidence level of AR in China was gradually increasing, and the gap with developed countries had narrowed [21]. Consequently, allergic diseases are increasingly affecting people’s health and quality of life [1].
Taking asthma as an example, the causes of allergic diseases are mostly related to indoor allergens, such as dust mites, moulds, and animal dander, among which dust mites are the most frequently involved [22]. A longitudinal population-based study, which included 29 centres (14 countries) mostly in western Europe, showed that AR related to dust mite allergies was associated with an increased risk of asthma independent of other allergens [23].
There is still no ideal treatment for diseases caused by dust mite allergy. In clinical practice, dust mite antigen extract infusion or drug inhibition can be used to reduce the immune tolerance of the body and thereby alleviate or relieve symptoms. However, although patients with an allergic constitution can reduce their symptoms through treatment, this condition is difficult to completely cure [24, 25]. Therefore, compared with expensive and long-cycle treatment, controlling the number of dust mites in the house and reducing the exposure of patients to allergens is an inexpensive and easy method to promote.
In clinical practice, several common methods for physical mite removal exist [26], such as anti-mite bed covers and anti-mite vacuum cleaners, but these measures cannot significantly reduce the number of live dust mites and remove hidden allergens. Chemical control for different purposes can be divided into two types: acaricides and other types. Acaricides can quickly and effectively kill individual dust mites but cannot effectively remove dust mite carcasses, faeces, and other allergens, and as chemical agents, their safety cannot be guaranteed. Repellent only enables avoidance of dust mites but cannot isolate allergens and is characterized by a bad odour, a thick and oily texture, no resistance to sweat or washing, and other defects. However, the mite bait used in this study enables an oligomeric aromatic factor compound and dust mite atopic agents to work together to induce dust mites to enter the bag and ingest only the agents effective against dust mites until they die, thus effectively achieving the purpose of blocking allergens.
The main effective component of the mite bait, emamectin benzoate, is a low-toxicity insecticide and acaricide. Emamectin is a highly effective biological agent synthesized on the basis of avermectin and has the characteristics of super-high efficiency, low toxicity (nearly non-toxic), no residue, and no pollution. Compared with that of avermectin, the insecticidal activity of emamectin benzoate is improved by 1–3 orders of magnitude, and it has very high activity against the larvae of lepidoptera insects, mites, and many other injurious insects. Emamectin benzoate has both the gastric toxicity and action of a contact poison, with a good effect at a very low dose (0.084~2 g/ha) [27]. After testing, the 0.1% emamectin benzoate used in the mite bait has slight toxicity through the skin, mouth, and nose. The product was found to attract 93% of dust mites, kill 74% of dust mites within 48 h, and kill nearly 100% of dust mites within 72 h.
At present, Chinese people with allergic diseases account for approximately 30% of the total population (approximately 400 million), with allergies especially affecting those who are young [28]. Based on the prevalence of childhood asthma in 2010, there were 6.7 million children with asthma in China alone. Therefore, the potential consumer group for this product is very large. If the efficacy and safety of this mite bait product can be confirmed for allergic diseases via this test, the product will provide a new tool for the treatment of such allergic diseases in the future.
Additionally, the random grouping, double-blind, crossover test method adopted in this study reduces the influence of selection bias, measurement bias, and other errors on the test results. Each subject will receive two schemes successively, which allows before-and-after comparison, eliminating individual differences while allowing inter-group comparison.
However, due to the long period of this study, problems, such as loss to follow-up, exit, and decline in compliance, may easily occur. Ensuring that each case is in the same condition in each phase of treatment is difficult.
To improve study compliance, we will contact the parents or guardians through WeChat during the study and receive the questions raised by them in real time. Parents and guardians will give consent for the collection of indoor dust mite specimens by staffs who will receive training and provide assessment of the complete specimen collection in strict accordance with sampling procedures. In terms of trial safety, we will track all the events during the study until the incident is alleviated, the situation is stable, other explanations of the incident are obtained, or the contact with the subjects is lost. Subjects are able to drop out of the study at any time and continue to receive standard treatment for rhinitis and asthma in the outpatient department.
In summary, this study will scientifically and objectively evaluate the effect of mite bait on improvement of rhinitis and asthma symptoms, which might provide a convenient means for prevention and treatment of allergic diseases involving the airways in children.