Ficus spp.

Code: k81
Latin name: Ficus spp
Source material: Proteins from Ficus spp
As a relevant indoor allergen, Ficus benjamina ranks third after mites and pets and before molds in a German clinic (7).

Allergen Exposure

Any workplace where green plants like ficus are handled. Naturally growing ficus plants in tropical areas have not been reported to cause allergy. Ficus benjamina (Fb), also known as Java willow, Ceylon willow and Bali fig tree, is a tropical non-flowering plant used ornamentally in homes and public places such as offices and hospitals. The allergens are originally located in the sap of the plant, but are present in dust collected from leaf surfaces and also in house dust on the floor, where the allergens may persist over a period of several months after removal of the plant (1). The main route for sensitization is probably by inhalation of airborne dust emanating from the leaves of the plant (3).

Potential Cross-Reactivity

With the possible exception of the India rubber tree, Ficus elastica robusta, there is a high degree of cross-reactivity between different Ficus species (8-9). Cross-reactivity between Fb and fig, the edible fresh fruit of Ficus Carica, has been reported in two patients, where one suffered an anaphylactic reaction and the other reported rhinoconjunctivitis, dyspnea and wheezing immediately after the ingestion of fresh fig. Specific IgE was positive for both fig and Ficus with Pharmacia CAP System, and fig extract could partly inhibit Fb positive serum, suggesting that these two varieties of Ficus share some common allergens. It is suggested that Fb was responsible for the initiating sensitization in both cases (10-11).

A frequent association between sensitization to Ficus species and natural rubber latex (NRL) from Hevea braziliensis has been reported and attributed to cross-reacting IgE antibodies (1, 7, 9, 12-13). The hypothesis has also been raised that allergy to Fb might induce cross-reactivity to the same fruits as does NRL allergy, namely avocado, banana, chestnut, kiwi. The increasing risk of sensitization to widely used latex devices and the extensive exposure to Ficus plants indicate increased allergenic risk from this newly recognized cross-reactivity.

Clinical Experience

Allergy to Fb was first observed in an occupational setting, where two plant leasing workers were sensitized and developed Fb-linked rhinitis and asthma. In a subsequent study in four plant-leasing firms, it was found that 27% of the workers had IgE antibodies to Fb. The sensitization occurred in atopic individuals as well as in non-atopic (3).
 
Since then, allergy to Fb has been reported to be around 3% among consecutive patients refered to a specialist for allergy investigation (4). These patients generally had a lower degree of exposure, and were sensitized in their homes or in public areas. Furthermore, non-atopic patients have been reported to develop allergic rhinoconjunctivitis, contact urticaria and asthma caused by Fb (5-6).
 
Review
The genus Ficus includes over 1000 species. About ten of these, plus several varieties, are available as indoor plants.
 
Ficus benjamina (Fb), also known as Java willow, Ceylon willow and Bali fig tree, is a tropical non-flowering plant used ornamentally in homes and public places such as offices and hospitals. It is decorative, easy to cultivate and it thrives indoors. The plant often grows into a small tree, reaching a height of 2-3 m. The allergens are originally located in the sap of the plant, but are present in dust collected from leaf surfaces and also in house dust on the floor, where the allergens may persist over a period of several months after removal of the plant (1). A total of 11 allergenic components have been identified, three of them major allergens (2).
 
Allergy to Fb was first observed in an occupational setting, where two plant leasing workers were sensitized and developed Fb- linked rhinitis and asthma. In a subsequent study in four plant-leasing firms, it was found that 27% of the workers had IgE antibodies to Fb. The sensitization occurred in atopic individuals as well as in non-atopic (3).
Since then, allergy to Fb has been reported to be around 3% among consecutive patients refered to a specialist for allergy investigation (4). These patients generally had a lower degree of exposure, and were sensitized in their homes or in public areas. Furthermore, non-atopic patients have been reported to develop allergic rhinoconjunctivitis, contact urticaria and asthma caused by Fb (5-6). The number of Fb sensitizations is now increasing. As a relevant indoor allergen, Fb ranks third after mites and pets and before molds in a German clinic (7). The main route for sensitization is probably by inhalation of airborne dust emanating from the leaves of the plant (3). With the possible exception of the India rubber tree, Ficus elastica robusta, there is a high degree of cross-reactivity between different Ficus species (8-9). Cross-reactivity between Fb and fig, the edible fresh fruit of Ficus Carica, has been reported in two patients, where one suffered an anaphylactic reaction and the other reported rhinoconjunctivitis, dyspnea and wheezing immediately after the ingestion of fresh fig. Specific IgE was positive for both fig and Ficus with Pharmacia CAP System, and fig extract could partly inhibit Fb positive serum, suggesting that these two varieties of Ficus share some common allergens. It is suggested that Fb was responsible for the initiating sensitization in both cases (10-11).
 
A frequent association between sensitization to Ficus species and natural rubber latex (NRL) from Hevea brasiliensis has been reported and attributed to cross-reacting IgE antibodies (1, 7, 9, 12-13). 
 
The hypothesis has also been raised that allergy to Fb might induce cross-reactivity to the same fruits as does NRL allergy, namely avocado, banana, chestnut, kiwi. 
 
The increasing risk of sensitization to widely used latex devices and the extensive exposure to Ficus plants indicate increased allergenic risk from this newly recognized cross-reactivity.

References

  1. Bircher AJ, Langauer S, Levy F, Wahl R. The allergen of Ficus benjamina in house dust [see comments]. Clin Exp Allergy 1995;25(3):228-33.
  2. Axelsson IG, Johansson SG, Larsson PH, Zetterstrom O. Characterization of allergenic components in sap extract from the weeping fig (Ficus benjamina). Int Arch Allergy Appl Immunol 1990;91(2):130-5.
  3. Axelsson IG, Johansson SG, Zetterstrom O. Occupational allergy to weeping fig in plant keepers. Allergy 1987;42(3):161-7.
  4. Axelsson IG, Johansson SG, Zetterstrom O. A new indoor allergen from a common non-flowering plant. Allergy 1987;42(8):604-11.
  5. Schmid P, Stoger P, Wuthrich B. Severe isolated allergy to Ficus benjamina after bedroom exposure. Allergy 1993;48(6):466-7.
  6. Axelsson IG. Allergy to Ficus benjamina (weeping fig) in nonatopic subjects. Allergy 1995;50(3):284-5.
  7. Schenkelberger V, Freitag M, Altmeyer P. [Ficus benjamina--the hidden allergen in the house]. Hautarzt 1998;49(1):2-5.
  8. Axelsson IG, Johansson SG, Larsson PH, Zetterstrom O. Serum reactivity to other indoor ficus plants in patients with allergy to weeping fig (Ficus benjamina). Allergy 1991;46(2):92-8.
  9. van Ginkel CJ, Dijkstra AT, van Eyk CL, den Hengst CW, Bruijnzeel-Koomen CA. [Allergy to Ficus benjamina: at the workplace and at home]. Ned Tijdschr Geneeskd 1997;141(16):782-4.
  10. Dechamp C, Bessot JC, Pauli G, Deviller P. First report of anaphylactic reaction after fig (Ficus carica) ingestion. Allergy 1995;50(6):514-6.
  11. Diez-Gomez ML, Quirce S, Aragoneses E, Cuevas M. Asthma caused by Ficus benjamina latex: evidence of cross-reactivity with fig fruit and papain. Ann Allergy Asthma Immunol 1998;80(1):24-30.
  12. Brehler R, Abrams E, Sedlmayr S. Cross-reactivity between Ficus benjamina (weeping fig) and natural rubber latex. Allergy 1998;53(4):402-6.
  13. Delbourg MF, Moneret-Vautrin DA, Guilloux L, Ville G. Hypersensitivity to latex and Ficus benjamina allergens. Ann Allergy Asthma Immunol 1995;75(6 Pt 1):496-500.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.