Mulberry

Further Reading

Red mulberry t71

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Code: t70
Latin name: Morus alba
Source material: Pollen
Family: Moraceae
Common names: White mulberry, Silkworm mulberry

Allergen Exposure

Geographical distribution
The Mulberries, comprising about 10 species, are monoecious or dioecious trees or shrubs. The origins of the Mulberry tree (M. alba) are mainly in China, Japan, Thailand and Malaysia. The tree is now found throughout the world. Only 2 species are native to North America, but several others have been introduced.

The Mulberry is a deciduous tree growing 18 to 20 m in height, with a wide-spreading, round top. The trunk is light grey. The green leaves may be unlobed, mitten-shaped, or 3-lobed.

The trees bear the staminate and pistillate flowers on different branches of the same tree or on different trees; these flowers are minute, and the staminate ones are in cylindric spikes up to 2 cm long (1). The tree flowers in spring and is wind-pollinated, and the pollen is dominant in its region. The pollen is highly allergenic. The seeds (fruits) ripen from summer. The fruit is an aggregate, 1 to 5 cm long, white becoming pink and then purplish to nearly black.

Environment
These trees are extensively grown in locations such as China, Southern Europe and India for their leaves as food for silkworms. Mulberries are popular for street planting and as garden and roadside ornamentals in the eastern US, Europe, and other places. Having escaped, trees often appear growing wild on roadsides and along fencerows.

The fruits may be eaten raw or cooked. The wood is valued for sporting goods due to its elasticity and flexibility when steamed.

Allergens
No allergens from this plant have yet been characterised.

Potential cross-reactivity

An extensive cross-reactivity among the different individual species of the genus, as well as a certain degree of cross-reactivity within the family Moraceae (including Breadfruit, Ficus spp. [Weeping fig], Fig, India rubber plant, and Jackfruit) could be expected (2).

Clinical Experience

IgE-mediated reactions
Mulberry pollens can induce asthma, allergic rhinitis and allergic conjunctivitis (3-4).

A study from Tuscon, Arizona, USA, concluded that Mulberry pollen is an important allergen associated with asthma and allergic rhinitis in children raised in a semiarid environment (5). In the tropical area of Caracas, Venezuela, Mulberry tree pollen was shown to be a frequently encountered aeroallergen (6).

Further studies, including from Spain and India, have shown Mulberry tree pollen to be an important aeroallergen (7-13). In a study of 30 patients in Santander, Spain, aged between 13 and 69 years, who suffered seasonal rhinoconjunctivitis symptoms and who had always lived in the area, it was found that 27% tested positive to Plantago, 20% to Quercus, and 13% to Mulberry tree pollen (14).

Mulberry pollen has also been recorded in the atmosphere of Didim, in southwestern Turkey (15). In a study conducted in the city of Heraklion, located in the center of the northern shore of the island of Crete, pollen from Moraceae was the seventh most prevalent pollen recorded (16). In a study of the pollen spectrum in La Plata, Argentina, 79 pollen types were represented. The most prevalent 10 pollens included pollen from Mulberry tree (17).

Airborne contact urticaria due to Mulberry pollen has been reported. (18)

Other reactions
Asthma and allergic rhinitis as reactions to the fruit of the Mulberry tree have been documented (19). Mulberry leaves have hypoglycaemic, hypotensive, diuretic and hypolipidaemic effects in diabetic patients (20).

The tree’s unripe fruit and milky sap are reported to result in stomach upset and hallucinations, but this is not substantiated by all authors.

Compiled by Dr Harris Steinman, harris@zingsolutions.com.

References

  1. Wodehouse RP. Hay fever Plants, 2nd ed. New York, NY: Hafner 1971:107-10
  2. Yman L. Botanical relations and immuno-logical cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09
  3. Navarro AM, Orta JC, Sanchez MC, Delgado J, Barber D, Lombardero M. Primary sensitization to Morus alba. Allergy 1997;52(11):1144-5
  4. Targow AM. The mulberry tree: a neglected factor in respiratory allergy in Southern California. Ann Allergy 1971;29(6):318-22
  5. Halonen M, Stern DA, Wright AL, Taussig LM, Martinez FD. Alternaria as a major allergen for asthma in children raised in a desert environment. Am J Respir Crit Care Med 1997;155(4):1356-61
  6. Hurtado I, Riegler-Goihman M. Air sampling studies in a tropical area. Four year results. Experientia Suppl 1987;51:49-53
  7. Sneller MR, Hayes HD, Pinnas JL. Pollen changes during five decades of urbanization in Tucson, Arizona.
    Ann Allergy 1993;71(6):519-24
  8. Hernandez Prieto M, Lorente Toledano F,
    Romo Cortina A, Davila Gonzalez I, Laffond Yges E, Calvo Bullon A. Pollen calendar of the city of Salamanca (Spain). Aeropalynological analysis for 1981-1982 and 1991-1992. Allergol Immunopathol (Madr) 1998;26(5):209-22
  9. Subiza J, Jerez M, Jimenez JA, Narganes MJ, Cabrera M, Varela S, Subiza E. Allergenic pollen pollinosis in Madrid.
    J Allergy Clin Immunol 1995;96(1):15-23
  10. Singh BP, Singh AB, Nair PK, Gangal SV.
    Survey of airborne pollen and fungal spores at Dehra Dun, India.
    Ann Allergy 1987;59(3):229-34
  11. Singh AB, Kumar P. Aeroallergens in clinical practice of allergy in India. An overview.
    Ann Agric Environ Med 2003;10(2):131-6
  12. Gonzalo-Garjo MA, Tormo-Molina R, Muñoz-Rodríguez AF, Silva-Palacios I. Differences in the spatial distribution of airborne pollen concentrations at different urban locations within a city. J Investig Allergol Clin Immunol 2006;16(1):37-43
  13. Garcia-Mozo H, Perez-Badia R, Fernandez-Gonzalez F, Galan C. Airborne pollen sampling in Toledo, Central Spain.
    Aerobiologia 2006;22(1):55-66
  14. de Benito Rica V, Menchaca Riesco JM, Rubio del Val MC, Sánchez Alonso Y, Rodríguez Lázaro B, Soto Torres J. Identification of the allergenic taxa of pollen in patients with pollinosis to determine the risk season. [Spanish] Allergol Immunopathol (Madr) 2004;32(4):228-32
  15. Bilisik A, Yenigun A, Bicakci A, Eliacik K, Canitez Y, Malyer H, Sapan N. An observation study of airborne pollen fall in Didim (SW Turkey): years 2004 - 2005.
    Aerobiologia 2008;24(1):61-6
  16. Gonianakis MI, Baritaki MA, Neonakis IK, Gonianakis IM, Kypriotakis Z, Darivianaki E,
    Bouros D, Kontou-Filli K. A 10-year aerobiological study (1994-2003) in the Mediterranean island of Crete, Greece: trees, aerobiologic data, and botanical and clinical correlations.
    Allergy Asthma Proc 2006;27(5):371-7
  17. Nitiu DS. Aeropalynologic analysis of La Plata City (Argentina) during a 3-year period. Aerobiologia 2006; 22(1):79-87
  18. Munoz FJ, Delgado J, Palma JL, Gimenez MJ, Monteseirin FJ, Conde J. Airborne contact urticaria due to mulberry (Morus alba) pollen. Contact Dermatitis 1995;32(1):61
  19. Romano C, Ferrara A, Falagiani P. A case of allergy to globe artichoke and other clinical cases of rare food allergy. J Investig Allergol Clin Immunol 2000;10(2):102-4
  20. Andallu B, Suryakantham V, Lakshmi Srikanthi B,
    Kesava Reddy G. Effect of mulberry (Morus indica L.) therapy on plasma and erythrocyte membrane lipids in patients with type 2 diabetes.
    Clin Chim Acta 2001;314(1-2):47-53

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