Keywords
hypersensitivity - allergens - environment - skin tests
Introduction
The increased prevalence of atopic diseases in all age groups is noted in the literature.[1] According to the World Health Organization (WHO), 35% of the world population has
some type of allergy, the same tendency as in Brazil.[2]
Medical intervention in allergies has broadened its perspective, also focusing on
the interference of atopy in the quality of life of patients. Impairments in sleep–wake
cycle and low academic and occupational performance are among the most prevalent complaints,
which raise the importance of proper intervention.[3]
[4]
[5]
As a principle in allergy treatment, before using pharmacotherapy, patients are instructed
to avoid exposure to the causal agent. However, this makes it necessary to study the
patient's environment.
The analysis of allergens in different locations in Brazil shows a difference between
the findings, with varying temperatures and humidities, on indoor microclimate and
external conditions.[3]
[6] Studies conducted in the middle Brazilian region showed a high prevalence of the
mite Dermatophagoides farinae,[4]
[5] and in some coastal regions there is a preponderance of Dermatophagoides pteronyssinus.[7]
[8]
[9] In both regions, house dust mites are quite prevalent.
Beyond these two species of mites, Dutra et al identified and related major aeroallergens
of our environment, including other house dust mites of the genus Blomia, pollens of Lolium multiflorum species, spores of fungi (Aspergillus, Penicillium, Alternaria), cockroach and animal epithelia.[9]
As an additional tool for both the physician and the patient, specific knowledge of
the etiology of allergy has great value. The identification of specific allergen is
performed by prick tests with an application of a drop containing the allergen in
the patient's forearm, then piercing the skin surface with an appropriate needle.[10] A positive test is observed when a wheal greater than or equal to the application
wheal of the positive control is formed (histamine 10 mg/mL).
Thus, given the large number and the immense variety of allergens in Curitiba-PR and
metropolitan area, as well as individual reaction to each allergen, an allergic profile
of this population would be beneficial. This will enable physicians to better guide
their patients with environmental control measures.
The present study aims to analyze the sensitization profile of patients of Center
Rhinitis and Allergy from Hospital X (specializing in otolaryngology) at Curitiba-PR
with allergic complaints and identify possible specific characteristics of each age
group and gender.
Methods
This descriptive cross-sectional study collected data from medical records from Multi-Test
II (Lincoln Diagnostics Inc. Decatur, Illinois) and Hospital X databases. An ethical
committee from Hospital Paranaense de Otorrinolaringologia Ltda.–IPO (Instituto Paranaense
de Otorrinolaringologia) approved this study on July 2013 under protocol number 366697.
The study population (a total of 1,912 patients) included those who had skin testing
(i.e., initial consultation) and all who had complaints or symptoms of allergic rhinitis:
sneezing, abundant clear rhinorrhea, nasal obstruction, and intense nasal itching.[11]
The study was conducted in three phases. At first, patients were identified through
the Multi-Test II database and the results of skin tests were recorded. Then, for
the collection of personal data (age and gender), the Hospital X database was searched.
Finally, patients were selected and analyzed with a database constructed by the authors.
Inclusion criteria were patients who underwent cutaneous prick test from Multi-Test
II (multiheaded devices) from March 14 to October 4, 2013, in Hospital X, Paraná,
Brazil. Patients were selected to reduce possible measurement bias, because the puncture
mechanism differs between all the other brands on the market. Exclusion criteria were
patients with incomplete and/or duplicate records and those whose allergy test identified
prior use of antihistamine or presence of dermatographism.
Skin was tested for allergenic extracts of fungi (Aspergillus, Penicillium, Alternaria, and Cladosporium), pollen (Cynodon dactylon [common grass], Dactylis glomerata [Rhodes grass], Festuca pratensis [and meadow fescue], L. multiflorum [ryegrass]), mites (Blomia tropicalis, D. farinae, D. pteronyssinus), and animal epithelia (dog and cat). All extracts were made by the same industry
Immunotec/FDA Allergenic from Rio de Janeiro, Brazil. The variables in these tests
were positive or negative response, wheal size, and presence or absence of pseudopodia.
Papule size formed after exposure to the allergen was classified as negative (0 to
2 mm), weak (3 to 4 mm), moderate (5 to 6 mm), strong (7 to 9 mm), or very strong
(greater than or equal to 10 or presence of pseudopodia).
Patients were grouped according to age, based on the WHO definition: children (0 to
9 years), adolescents (10 to 19 years), adults (20 to 59 years), and elderly (60 or
more).
All data were organized into spreadsheets in Microsoft Office Excel 2007 (Microsoft
Corp., Redmond, Washington, United States) according to age, gender, type of allergen,
and skin test result and subsequently analyzed.
Results
We analyzed 2,132 charts of patients with previous allergic complaints who underwent
skin prick test with Multi-Test II from March 14 to October 4, 2013, in Hospital X,
Paraná, Brazil. However, only 1,912 met the inclusion criteria of the study. The other
220 patients were excluded for the following reasons: presence of dermatographism,
previous use of antihistamine, incomplete records, and duplicated tests (one case
of duplicated test was included, the latest one).
The final sample of patients contained both sexes, with ∼60% male (1,151) and 40%
female (761). Ages ranged from 3 to 87 years, with an overall average age of 28.5
years ([Table 1]).
Table 1
Distribution of patients by age group
|
Age group
|
Middle age (y)
|
Total (%)
|
|
Children (≤9 y)
|
7
|
195 (10.2%)
|
|
Teenagers (10–19 y)
|
14.5
|
425 (22.2%)
|
|
Adults (20–59 y)
|
33.5
|
1185 (62%)
|
|
Elderly (≥60 y)
|
67
|
107 (5.6%)
|
|
Sample: 3–87 y
|
28.5
|
1912 (100%)
|
Tests were performed with four types of aeroallergens: dust mites (D. pteronyssinus, D. farinae, B. tropicalis), fungi (unique blend of Alternaria, Cladosporium, Aspergillus, and Penicillium), pollen (C. dactylon, D. glomerata, F. pratensis, and L. multiflorum), and animal epithelia (dog and cat). A total of 10 types of allergenic extracts
were performed in 1,912 patients.
The wheal size of the positive control did not exceed 10 mm and the minimum extent
observed among children, adolescents, adults, and the elderly were, respectively,
4, 6, 5, and 7 mm. All negative controls had 0 mm.
Regardless of gender and/or age, tests of 1,360 patients (∼71%) were positive for
at least one type of allergen. Among them, the main etiologic agents of atopy were
mostly mites D. pteronyssinus and D. farinae, each with ∼60% of the total analyzed. A smaller allergic response was obtained with
dog epithelia and fungi extract, with values below 5% ([Fig. 1]).
Fig. 1 Results of allergy tests performed according to the type of allergen extracts used
(total = 1,912).
Also, 64.4% of patients (1231) showed sensitivity to at least one species of mite
tested, 4.3% (82) to fungi, 28.1% (538) to one or more kinds of pollen, and 17.3%
(330) to animal epithelia. In the study, only one patient was sensitive to all inhalant
allergens tested.
In females (total = 1,151), 67% had a positive allergy test for any statement, and
in males (total = 761), 77.4%. The proportion of responses to allergens followed a
very similar pattern between sexes and when compared with the total group: increased
prevalence of sensitivity to mites and fungi and the lower dog epithelia ([Figs. 2] and [3]).
Fig. 2 Results of allergy tests performed according to the type of allergen extracts used
in female patients (total = 1,151).
Fig. 3 Results of allergy tests performed according to the type of allergen extracts used
in male patients (total = 761).
Groups were divided by age. From 0 to 9 years, 119 (61%) were susceptible to at least
one type of allergen, and of these, 97% were sensitive to one of three types of mite.
From 10 to 19 years, 363 (85.5%) showed positive results to one or more statements.
Following the same analysis criteria, 841 (71%) were positive in the range of 20 to
59 years, and 37 (34.5%) were also positive in the sample above 59 years old. The
mites were responsible for most of positive results, especially among teenagers. Next
were the pollens, with similar quantities in adults and adolescents ([Table 2] and [Fig. 4]).
Fig. 4 Positive results considering the two most prevalent allergen classes and the total
in each age group.
Table 2
Number of positive results for one or more allergens according to age
|
0–9 y
|
10–19 y
|
20–59 y
|
>59 y
|
|
Total of tests
|
195
|
425
|
1185
|
107
|
|
Positives
|
119 (61%)
|
363 (85.5%)
|
841 (71%)
|
37 (34.5%)
|
D. pteronyssinus was the most prevalent mite in all age groups. D. glomerata and F. pratensis were the most prevalent pollens. Both children and adolescents showed higher positivity
to cat extract than other animals: 26.15% ([Figs. 5] and [6]).
Fig. 5 Positivity of tests in relation to dust mites, pollens, and animal epithelia in (A)
children (total = 195) and (B) teenagers (total = 425).
Fig. 6 (A) Positivity of tests in relation to dust mites and pollens in (A) adults (total = 1,185)
and (B) elderly (total = 107).
The highest sensitivity was observed with mites, reaching levels close to 50% for
each type. Fungi and dog epithelia showed fewer positive results.
Mites had strong (wheal 6 to 10 mm) and very strong (wheal equal or over 10 mm) predominant
reactions. Among pollens, D. glomerata (60% positive) showed strong reaction and F. pratensis, very strong (50% positive). Tests with epithelia showed 15.7% positivity for cat
subtype, predominantly papules with strong reaction, and only 2.5% for subtype dog
([Fig. 7]
).
Fig. 7 Distribution of results according to the reaction and type of allergen.
Papules varied in size in positive tests. The minimum recorded was 4 mm (upper limit
of mild rating) for all allergens except for P. multiflorum (pollen). The maximum size ranged according to the types of allergens: mites and
pollens had larger sizes (15 to 16 mm) and fungi and epithelia, smaller ([Table 3]).
Table 3
Positive tests: variation in papule size according to the type of allergen
|
Allergens
|
Minimum (mm)
|
Maximum (mm)
|
Middle (mm)
|
|
Mite Blomia tropicalis
|
4
|
15
|
8.4
|
|
Mite Dermatophagoides farinae
|
4
|
15
|
9
|
|
Mite Dermatophagoides pteronyssinus
|
4
|
15
|
8.7
|
|
Fungi
|
4
|
10
|
7
|
|
Pollen Cynodon dactylon
|
4
|
12
|
7.3
|
|
Pollen Dactylis glomerata
|
4
|
16
|
8.5
|
|
Pollen Festuca pratensis
|
4
|
15
|
9.2
|
|
Pollen Lolium multiflorum
|
5
|
15
|
8.9
|
|
Dog epithelium
|
4
|
10
|
7
|
|
Cat epithelium
|
4
|
10
|
7.4
|
The intensity of the reaction was also different between age groups irrespective of
the allergen. The group of seniors had papules of small sizes, albeit in very strong
reactions ([Table 4]).
Table 4
Positive tests: variation in papule size according to age group
|
Age groups
|
Minimum (mm)
|
Maximum (mm)
|
|
Children
|
5–7
|
15
|
|
Teenagers
|
4–5
|
14–15
|
|
Adults
|
4
|
15–16
|
|
Elderly
|
5–7
|
8–13
|
Pseudopodia, indicating strong sensitivity to allergens, was present in both genders
and in all age groups, with the vast majority (99%) showing wheals of 10 mm. Pseudopodia
by itself were not detected in the following groups: females, children and the elderly,
using dog epithelia extract; elderly, using cat dander; and in all age groups except
adults when fungi extract.
Discussion
Currently the most practical method to verify the individual's sensitivity to some
allergen is through the prick test. The Multi-Test II was chosen because it allows
simultaneous application of eight allergenic extracts, guaranteeing lower divergence
between the amounts administered. We chose only the prevalent aeroallergens in Curitiba,
Paraná, Brazil and metropolitan region,[9] because food allergy is commonly known by the patients themselves.
The literature shows no influence of sex on the prevalence of atopic diseases, which
was also shown in this study.
This study revealed that 71% of patients were positive for at least one of the extracts
used, being mostly mites, followed by pollens. The results are close to those obtained
by Soares et al,[12] at 73.5%, and the 67.5% by Feld et al,[13] even though those studies were performed in other states, which is explained by
the fact that studies tend to be done in areas in which aeroallergens are present.
Castro found D. pteronyssinus, D. farinae, and B tropicalis,[14] all belonging to the group of mites, to be the key antigens found in immunoallergic
tests in patients with respiratory allergy. It is clear that in fact these three species
also have high prevalence in this study, which corroborates another study by Dutra
et al, in the city of Curitiba.[9]
The grass L. multiflorum is the most widespread in the city of Curitiba and nearby. Pollination occurs from
September to December, the period of this study, and causes the most intense reactions
to skin tests compared with other species.[15] However, our results showing the pollen species D. glomerata and F. pratensis claiming more reactions in all age groups diverge from results in the literature.
Although the Curitiba climate has a high relative humidity throughout the year, fungi
do not have a high impact. The extract used showed low prevalence of positive tests,
around 4.5% of 1,912 tests. In Brazil the prevalence varies from 2.2 to 33%.[16]
The study showed a very low sensitivity to animal epithelia, 17.3%, yet the positive
response was greater with cat dander extract. A similar result was seen by Vieira
et al.[17] In Brazilian regions within the age group of 3 to 16 years, Rizzo et al in their
study found 3.1% positive for dog epithelia and the same percentage for cats,[2] values that were not similar when restricted to the region of our study: 1.7% and
26.15%, respectively.
The assessment of the presence or absence of pseudopodia is always made in skin tests,
but it is almost nonexistent in the literature.
The present study examined the formation of these irregularities in papules in all
age groups and both genders, which may rule out the influence of these factors. However,
extracts of animal epithelia in specific age groups, especially children and the elderly,
have not revealed scaly papules. According to the III Brazilian Consensus on Rhinitis
2012,[11] the major cat allergen is produced by sebaceous glands and secreted by the skin,
similar to dogs but with less allergenic component. There is evidence that exposure
to household animals at an earlier stage of life before the occurrence of awareness
can have a protective effect on atopic sensitization and allergic manifestations.
Conclusion
Sensitivity to aeroallergens depends on multiple factors, including the micro- and
macroenvironment in which the individual is exposed. Males and females are both atopic,
with no increased predisposition of some specific aeroallergen. Likewise, sex does
not interfere with response antigen intensity.
Among the most prevalent aeroallergens in the region of this study, the genus Dermatophagoides has also been present in most similar studies. Research involving other types of
pollens, other than the Lolium genus, are needed, because different species predominated in this study. Fungi and
animal epithelia were not considered aeroallergens with a great potential to cause
symptoms, which differs from common sense and would indicate redirection of prophylactic
measures in the intervention of allergies.
