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e6 Guinea pig epithelium

Code e6
LOINC LP16990-1
Family Caviidae
Genus Cavia
Species C. porcellus
Source Material Epithelium and dander
Latin Name Cavia porcellus
Other Names Domestic cavy, domestic guinea pig
Categories Epidermal and Animal Proteins

Summary

Cavies porcellus are domesticated guinea pigs that belong to the family Caviidae and genus Cavia. These species have stocky bodies, delicate short limbs, rounded hairless pinnae, with no tails. They are distributed throughout the Andean area of South America. For over many decades, guinea pigs have been used as pets and laboratory species globally. Guinea pig urine, saliva, dust, dander and fur are more intense extracts compared with entire pelt, defecation, and serum. Since the size of airborne particles obtained from guinea pig urine and dander are very minute, it can easily enter the lower respiratory tract and cause allergic symptoms. Allergic sensitization and reactions to guinea pig allergy have commonly been reported in individuals, especially in laboratory animal handlers, mainly resulting in allergic rhinitis, asthma and rhinoconjunctivitis. Among all the allergens, Cav p 2 and 3 are considered as major allergens (IgE prevalence: 65% and 54%) that work as potential biomarkers for guinea pig allergy. Literature have found no cross-reactivity between major guinea pig allergens (Cav p 2 and 3) and cat, dog and hamster extracts; whereas cross-reactivity was reported between minor allergen Cav p 4 and dog, cat and horse allergens.

Allergen

Nature

Cavies porcellus also known as domesticated guinea pigs are rodent species that belong to the family Caviidae and genus Cavia (1).

Guinea pigs exhibit a very distinctive appearance that includes stocky bodies, short limbs, rounded hairless pinnae, with no tail. The males are bigger in size in comparison to females (males: 900 to 1,200 g vs. females: 700 to 900 g). Domestic guinea pigs live an average of about 5 to 6 years. The hair coat of guinea pigs consists of large guard hairs that are enveloped by an undercoat of fine hairs. Sebaceous glands are androgen-dependent and are abundant particularly along the dorsum and around the anus. Guinea pigs have four toes on the front feet and three toes on the hind; each having a short claw. All teeth are elodont and continue to grow throughout life (2). The female guinea pig present with only two areolas and mammary glands, that are situated in the inguinal region, whereas the mature male has extremely large seminal vesicles, which pass forward as twin horns in the ventral abdominal cavity (3).

Several colors (white, black, brown, red, brindle, and roan) and hair-coat varieties of guinea pig are available. They may be mono-, bi-, or tricolored and have either short regular hair (short hair or English), longer hair arranged in whorls (Abyssinian), long straight hair (Peruvian), or medium-length fine hair (silky). Guinea pigs are polyestrous and breed year-round, under laboratory settings. In most females, the estrous cycle is approximately 16 days, and ovulation is spontaneous (4).

Habitat

Of all the South American rodents, guinea pigs are the most abundant and widespread. They are habituated to live in a variety of habitats, ranging from tropical flood fields through open grasslands and forest edges to rough glades 4,000 m (13,000 ft) up, preparing themselves to forage (5). Guinea pigs readily adapt to the husbandry system and workday environment in the laboratory setting (2).

Taxonomy

Taxonomic tree of Cavia porcellus (6)
Domain Eukaryota
Kingdom Metazoa
Phylum Chordata
Subphylum Vertebrata
Class Mammalia
Order Rodentia
Family Caviidae
Genus Cavia
Species C. porcellus

 

Tissue

Guinea pigs are preferred as domestic pets as a result of their little size and the negligible time and cost associated with their care. The guinea pig urine, saliva, dust, dander and fur are considered as more intense extracts when compared with the entire pelt, defecation, and serum. It has been found that inhalant allergens might be obtained from the material that gets discharged from guinea pig coat, after contamination with urine and saliva (7).

The size of airborne particles obtained from guinea pig urine and dander leading to the most allergenic activity have been demonstrated to be of a diameter of either >5 microns or <0.8 microns, sufficiently small to enter the lower respiratory tract when breathed in. Hence, it may not be surprising to see that individuals being sensitized to guinea pigs may acquire asthma easily (7).

Recently, two new allergens i.e. guinea pig lipocalins Cav p 2 and Cav p 3 have been identified as the major allergens. These allergens have shown to improve the diagnosis of guinea pig allergic patients (8).

Epidemiology

Worldwide distribution

Laboratory animal allergies (LAA) and asthma pose a significant occupational disease for a huge number of technicians, animal caregivers, physicians, and researchers whose job demands such exposure. Sensitization related to occupation may lead to the development of skin reactions, asthma, allergic rhinitis, rhinoconjunctivitis, and increased bronchial responsiveness (9). Clinical manifestation of LAA includes nasal symptoms (e.g., sneezing, congestion and watery discharge) and skin rashes. Asthma, accompanied by cough, wheezing, and shortness of breath, may affect 20% to 38% of laboratory technicians who are sensitized to LAA. Pre-existing allergies to pollens, molds and dust mites; exposure to LAA; and possibly the use of tobacco is considered to be the risk factors for acquiring LAA (10).

A cross-sectional study in Brazil that determined the prevalence of respiratory allergies in laboratory technicians found that the sensitization to work-related allergens was reported to be greater among animal handlers in comparison to non-animal handlers (16% vs. 3%, p<0.01). Out of 455 animal handlers, 10.8% (n=49) were exposed to guinea pigs. Furthermore, 9.6% (n=43) of these animal handlers reported asthma, 2.8% (n=12) reported work-related asthma, 58.1% (n=263) reported rhinitis, 29.6% (n=134) reported rhinoconjunctivitis, 34.3% (n=156) reported red and irritated skin, and 10.7% (n=48) reported LAA (9).

 

In a cross-sectional survey 169 individuals employed in Kochi Medical School, Japan was enrolled. The study group was instructed to fill out a questionnaire to assess the symptoms associated with exposure to laboratory animals. The results reported an overall prevalence of LAA to be 17.6%. Furthermore, the most commonly reported symptoms were allergic rhinoconjunctivitis (2.4%) and asthma (3%). Among the 22 guinea pig handlers, LAA was reported in 9.7% (11).

Risk factors

Allergic sensitization and reactions to guinea pigs have been frequently reported by laboratory animal handlers. The laboratory technicians exposed to guinea pigs have reported allergic symptoms, including asthma, allergic rhinitis and conjunctivitis (7)

Guinea pigs exhibit high allergenic potential, because of which they induce a high rate of sensitization in the laboratory animal workers, thus leading to various allergic symptoms. Hypersensitive manifestations are often severe (12).

Since the size of airborne particles derived from guinea pig urine, saliva and dander are minutes, allergic diseases such as asthma can easily occur in individuals sensitized to guinea pig (7).

Recent studies from Canada report that technicians working in animal research facilities are at a higher risk for developing LAA if they were atopic, had respiratory symptoms in the pollen season, were sensitized to dog or cat allergens, had baseline airway hyper-responsiveness, and/or had an increased hour of exposure with laboratory animals (10).

Risk factors for sensitization to pets (cats, dogs, and guinea pigs) were studied in 169 male individuals aged between 15 to 17 years. Of these individuals, 30.8% (n=52) reported recent or past history of contact with cats, 24.9% (n=42) with dogs and 11.8% (n=20) with guinea pig in their homes. Furthermore, clinically manifested allergy was observed in two individuals who showed allergic reactions to cats (one with asthma and the other with allergic rhinitis); and the other two being allergic to guinea pig (rhino-conjunctivitis). Three of the four individuals had past exposure to pets and one with allergic rhinitis to cats had never had any exposure to pets. A higher incidence of cat sensitization was seen in cat owners compared to individuals without direct exposure (26.9% versus 10.3%, p<0.01). No statistically significant difference in sensitization to dogs and guinea pigs was observed in either group (13).

Environmental Characteristics

Living environment

Domestic guinea pigs are an essential food source, with an exceptionally high protein content (19%) for some individuals living in the Altiplano area of South America. They have been used as pets and laboratory species worldwide for many years now. These domesticated rodents are raised by families and been regularly left uncaged to scavenge for food (2). In light of archeological proof, the domestic guinea pig in the Central Andes was eaten as food, which further fulfilled the ritual as well as social needs. Among the Inca, these rodents were correlated with high societal status community members and utilized as ceremonial offerings for last rites. Current non-domesticated populaces of domestic guinea pigs are available in eastern Cuba, and some farmers reportedly raise these guinea pigs for their meat (14). Furthermore, for many decades these creatures have most commonly been chosen for biological and biomedical research in laboratories (15).

Worldwide distribution

The guinea pigs are broadly distributed all through the Andean area of South America, i.e. from Venezuela to Buenos Aires Province, Argentina (16). The progenitors of the present laboratory guinea pigs were presumably being first brought into Europe from South America around 400 years ago. Various species of wild guinea pigs are distributed throughout the Andean highlands and the plains of South America and have for quite a long time been more or less domesticated by the Indians of those areas as a food source (3). In fact, guinea pigs are one of the only two non-indigenous domesticated animals presented to the Caribbean archipelago during the pre-Columbian time. Post A.D. 500, humans started shifting these domestic guinea pigs —via canoe—from the South American mainland to the Greater and Lesser Antilles, and to the southern Caribbean (Aruba, Bonaire, and Curaçao) islands (14).

Route of Exposure

Main

Airway inhalation is the main route of exposure to guinea pig allergen (10). The allergens derived from airborne particles are mostly found in guinea pig’s urine, dander and saliva. As the airborne particles are very small, it can easily penetrate through the lower respiratory tract, when breathed in (7).

Secondary

The secondary route of exposure includes direct skin and eye contact. Percutaneous exposures can happen from the bite of an animal, contaminated needles containing animal allergens, antigen contamination of wounds, and cuts on a person’s hand (10).

Detection

Allergic sensitization and reactions to Guinea pig have been commonly reported in laboratory animal handlers, primarily resulting in allergic rhinitis, asthma and rhinoconjunctivitis (7).

Allergic rhinitis

A cross-sectional study performed in Brazil examined the prevalence of respiratory allergies in laboratory animal technicians (n=455). The results reported that 58.1% (n=263) of laboratory animal handlers suffered from allergic rhinitis. Furthermore, among the 22 guinea pig handlers, LAA was reported in 9.7% (9).

Two case studies were conducted that studied the severe allergic reactions among females who were exposed to a guinea pig. In one case study, ocular itching, periorbital angioedema and lacrimation were reported in an 11-year-old girl after holding a guinea pig. The symptoms progressed to facial urticaria and angioedema, throat tightness, severe dyspnea and rhinorrhea. She experienced difficulty in talking and further expressed a sense of a life-threatening situation. Specific immunoglobulin E antibodies to guinea pig were found to be strongly positive (>17.5 kU/L). Another case study was of a 24-year-old female who developed severe allergic symptoms, a few minutes after cleaning her pet guinea pigs cage. She reported severe dyspnea, throat tightness, and suffered anxiety. A percutaneous skin testing reported positive for guinea pig epithelium extract (7).

Asthma

A cross-sectional study was conducted in Brazil to examine the prevalence of respiratory allergies in laboratory animal workers (n=455). The results found that 9.6% (n=43) and 2.8% (n=12) of laboratory animal handlers reported asthma and work-related asthma, respectively (9).

A study was conducted in India to examine the role of animal dander in the etiology of bronchial asthma. Intradermal and bronchial provocation tests with guinea pig whole pelt extracts were carried out on 68 individuals having asthma. The result showed significant positive skin reactions in 1.4% of the individuals (17).

Other diseases

In a cross-sectional study performed in Brazil, the prevalence of respiratory allergies in laboratory animal technicians was studied. Out of 455 animal handlers, 10.8% (n=49) were exposed to a guinea pig. Furthermore, 29.6% (n=134) of laboratory animal handlers were reported to have rhinoconjunctivitis (9).

Prevention and Therapy

Prevention strategies

Avoidance

Use of personal protective equipment can diminish the allergen exposure of animal handlers alongside offering protection to the animals from irresistible infectious agents that might be presented by skin, clothing, and shoes. Respirators likewise give an elevated level of security against LAA. Furthermore, laboratory animal handlers who used gloves, masks, laboratory coats, shoe covers, and respirators showed a reduction in allergic symptoms by 58% (9).

Changing of animal cage results in an intense level of exposure to allergens and is considered as an ergonomic risk factor. However, it has been observed that the use of a ventilated cage-changing wagon decreased the exposure of allergen from 77 to 17 ng/m3 and further enhanced the posture during work (18). 

Molecular Aspects

Allergenic molecules

Guinea pig urine, saliva, and epithelium are the major source of allergy. Five allergens have been formally named from guinea pig epithelium by the World Health Organization/ International Union of Immunological Societies (WHO/IUIS) allergen nomenclature sub-committee. Cavia porcellus (Cav p) 1 has been incompletely characterized, yet it is considered to be of the lipocalin family. Cav p 2 and Cav p 3 are also lipocalins that are found in hair extracts, eventually being isolated from accessory lacrimal glands and submandibular glands (19, 20). Both Cav p 2 and Cav p 3 are major (significant) allergens with IgE prevalences of 65 and 54%, respectively (21). Cav p 4 is cross-reactive serum albumin and is regarded as a minor allergen (19, 20), whereas Cav p 6 is a lipocalin having high sequence identities with Fel d 4, Equ c 1, and Can f 6 (19).

Guinea pig allergens recognized by WHO/IUIS Allergen Nomenclature Sub-Committee (19)

Allergen

MW(kDa)

Cross-reactivity/species specificity

Protein family

Cav p 1

20

No data

Lipocalin

Cav p 2

17

Species-specific

Lipocalin

Cav p 3

18

Species-specific

Lipocalin

Cav p 4

66

Cross-reactive with albumins from other mammals

Serum albumin

Cav p 6

18

Probably cross-reactive, with Fel d 4, Can f 6, and Equ c 1

Lipocalin

IUIS: International Union of Immunological Societies; kDa: Kilodaltons; MW: Molecular weight; nd: Not determined; WHO: World Health Organization

Biomarkers of severity

Cav p 2 and 3 are regarded as major allergens with high IgE prevalences. Since neither of these two allergens showed cross-reactions with dog and cat allergens, thus making them a potential biomarker for guinea pig allergy (19, 20).

Cross-reactivity

As no cross-reactivity has been reported between major guinea pig allergens (Cav p 2 and 3) and cat and dog concentrates, they appear to be species-specific marker allergens. Cav p 4 is cross-reactive serum albumin that showed cross-reactivity with dog, cat and horse allergens, whereas Cav p 6 is a lipocalin with high sequence similarities with Fel d 4, Equ c 1, and Can f 6 (19, 20).

No cross-reactivity among hamster and guinea pig extracts (Cav p 2 and 3) has neither been observed. Furthermore, the antibodies recognized in these two cases are antigen-specific and hence significant (7).

Compiled By

Author: Turacoz Healthcare Solutions

Reviewer: Dr. Magnus Borres

 

Last reviewed: November 2020

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