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 Table of Contents  
CASE REPORT
Year : 2017  |  Volume : 7  |  Issue : 4  |  Page : 221-223

Irritant contact keratitis caused by the bodily fluids of a brown marmorated stink bug


1 Department of Ophthalmology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
2 Department of Ophthalmology, Shin Kong Wu Ho-Su Memorial Hospital; School of Medicine, Fu Jen Catholic University, Taipei, Taiwan

Date of Submission13-Mar-2017
Date of Acceptance05-Jul-2017
Date of Web Publication5-Dec-2017

Correspondence Address:
Chao-Chien Hu
Department of Ophthalmology, Shin Kong Wu Ho-Su Memorial Hospital, No. 95, Wen-Chang Road, Shih-Lin District, Taipei 11120
Taiwan
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/tjo.tjo_32_17

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  Abstract 

PURPOSE: The brown marmorated stink bug is native to Asia (China, Taiwan, Japan, and the Korean peninsula). Its bodily fluids are toxic and irritating to the human skin and eyes. Human case reports are rare. Only one report of irritant contact dermatitis has been published. We report a case of irritant contact keratitis resulting from the chemical components of the bodily fluids of the bug.
MATERIALS AND METHODS: A case report.
RESULTS: A 74-year-old male presented to our emergency department with pain and redness in his right eye, which had been exposed to the bodily fluids of a brown marmorated stink bug. A patch of central corneal epithelial defect with conjunctival congestion and chemosis was found in his right eye. His best-corrected visual acuity (BCVA) (OD) was 6/20. We prescribed topical antibiotic and lubricant medications. The corneal epithelial defect recovered gradually over the course of several days. BCVA worsened to 2/60 but recovered gradually to 6/8.6 after the epithelial defect healed and after use of topical steroid for suppression of the local inflammation.
DISCUSSION: The adult brown marmorated stink bug is characterized by its shield shape and its dark, mottled, brown color. The stink bug ranges in length from 14 to 17 mm. A startled stink bug will react by biting or spraying a foul-smelling liquid from its thorax. When disturbed or crushed, the stink bug excretes a highly potent, odorous smell. The major component of the bodily fluids is trans-2-decenal and trans-2-octenal, chemicals that belong to the aldehyde group. Hydrogen ions (H+) produced by reduction and oxidation of aldehyde can induce chemical burn injuries to the ocular surface. Irritant contact keratitis may occur through this mechanism.
CONCLUSION: Stink bugs excrete odorous bodily fluids as a defensive mechanism when threatened. If the toxic fluid gets into the human eye, it can cause unexpected chemical burns or injury. Patients whose eyes come into contact with these bodily fluids should rinse their eyes thoroughly and immediately seek medical attention.

Keywords: Brown marmorated stink bug, chemical burns, contact keratitis, Halyomorpha halys


How to cite this article:
Shen YS, Hu CC. Irritant contact keratitis caused by the bodily fluids of a brown marmorated stink bug. Taiwan J Ophthalmol 2017;7:221-3

How to cite this URL:
Shen YS, Hu CC. Irritant contact keratitis caused by the bodily fluids of a brown marmorated stink bug. Taiwan J Ophthalmol [serial online] 2017 [cited 2021 Apr 22];7:221-3. Available from: https://www.e-tjo.org/text.asp?2017/7/4/221/216936


  Introduction Top


The brown marmorated stink bug, Halyomorpha halys, is native to Asia (China, Taiwan, Japan, and the Korean peninsula). The stink bug has also become a major agricultural pest and a nuisance to home and business owners in the Mid-Atlantic United States, including Maryland, Pennsylvania, and others.[1]

Although mostly a concern to agribusiness orchards,[2] such as for stone fruits and apples, and also seriously damaging to numerous other crops such as berries and oybeans, only few reports of human diseases, such as irritant contact dermatitis,[3] have been associated with the brown marmorated stink bug. We report a case of irritant contact keratitis resulting from the toxic chemicals released by the bug. For diagnosis of the chemical burns, we use organic chemistry concepts to explain the toxic reaction caused by the bodily fluids of the stink bug.


  Materials and Methods Top


A case report.


  Results Top


A 74-year-old male presented to our emergency department with pain and redness in his right eye, which had just been exposed to the bodily fluids of a stink bug. According to his statement, a stink bug ejected an amount of bodily fluids from its abdomen while he was trying to crush the bug.

On presentation, at the emergency department, a patch of central corneal epithelial defect with conjunctival congestion, and chemosis was found under slit-lamp [Figure 1]. The PH value was 6.0 noted at emergency department. After copious normal saline irrigation (2000 ml), test strips revealed a PH value change from 6.0 to 7.0. The patient's best-corrected visual acuity (BCVA) (OD) was 6/20 after testing on a Snellen chart, and the intraocular pressure was within the normal range. We prescribed chloramphenicol eye drops 0.25% administered every 6 h and erythromycin ointment 0.5% administered twice a day. We found mucoid discharge with conjunctival pseudomembrane on the 4th day. The pseudomembrane was removed under slit-lamp, and we added balanced salt solution administered every 2 h, keeping observation for reepithelialization. However, the BCVA had decreased to 2/60 at 1 week, with much discharge though the epithelium had gradually healed [Figure 2]. The balanced salt solution was kept for one additional week. The corneal epithelial defect recovered, with only some punctate epithelial erosions remaining, and BCVA was 6/15; we added fluorometholone 0.1% four times a day to reduce the inflammation. The BCVA recovered to 6/8.6 after 1 month [Figure 3], along with much improvement of the irritation, and only lubricant was continued for the clinical follow-up.
Figure 1: At the emergency department, a central ovoid shape corneal epithelial defect was found with a gravity-track appearance. Left picture: Gross figure under slit lamp. Right picture: Fluorescein dye staining picture

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Figure 2: One week later, the best-corrected visual acuity worsened to 2/60. Left picture: Descemet's membrane folding was noted. Right picture: Mild mucus discharge could be seen. The epithelial defect healed gradually with a healing line

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Figure 3: One month later, the epithelial defect healed gradually with some residual corneal opacity, and few punctate epithelial erosions remained. Left picture: Slit lamp picture. Right picture: Fluorescein dye staining picture

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  Discussion Top


The adult brown marmorated stink bug [Figure 4] is characterized by its shield shape and dark, mottled brown color.[4] The white banded antennae and dark banding on the edge of the wings are distinguishing characteristics. Stink bugs range in length from 14 to 17 mm. The brown marmorated stink bug belongs to the Pentatomidae family, of the genus Halyomorpha [Table 1].[5] A threatened stink bug will react by emitting a foul-smelling liquid from its scent gland on the thorax,[6],[7] from which it can release its pungent, protective secretions. When disturbed or crushed, the stink bug excretes a highly potent, odorous smell.
Figure 4: The stink bug, captured by our patient. the appearance of the adult stink bug characterized by a shield-shape and mottled brown color. Although the pictures were not clear due to photo by the patient unexpectedly, the white-banded antennae and dark bands on the edge of the wings could be seen

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Table 1: General classification of stink bug

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We reviewed the literature about chemical components of the secretions of the Pentatomidae family. Our results showed mixtures composed of aldehydes, esters, acids, and alcohols.[8] The major components responsible for the odor are trans-2-decenal and trans-2-octenal, which make up the majority of the bodily fluids, exhibiting properties as an aldehyde,[3],[9],[10] Aldehyde is a clear, colorless to light yellow liquid that boils at room temperature and is water soluble. Aldehydes are highly reactive and are active in many chemical reactions,[11] notably reduction, and oxidation. In reduction, the formyl group (-CHO) can be readily reduced to a primary alcohol (-CH2 OH). Typically, this conversion is accomplished by catalytic hydrogenation, either directly or by transfer hydrogenation. In oxidation, the formyl group of the aldehyde, can readily oxidizes to the corresponding carboxylic acid (-COOH),[12] which will release hydrogen ions (H +) into human tears.

Hydrogen ions (H +) are released onto the ocular surface and can cause acidic chemical burns to occur; this explains the PH value of approximately 6.0 discovered by our emergency department. This causes damage by denaturing and precipitating proteins in the corneal tissues that the ions contact.

The coagulated proteins act as a barrier to prevent further penetration.[13],[14] The mild concentration of alcohol causes solvent denaturation of the proteins on the ocular surface.[15] All of these conditions explain the patchy corneal epithelial damage, with the gravity tract-like effects over the areas where the chemicals flowed. In addition, the energy released by the chemical reaction, usually expressed as heat, may possibly induce thermal burns on the cornea. The mechanism described above could be responsible for inducing the irritant contact keratitis.

Returning to the overall course, the lubricants added a positive effect to the corneal epithelial recovery. However, the BCVA was still lowered due to the inflammatory process. In the case of chemical burn injuries, topical steroids should be considered early on while the epithelium is healing.


  Conclusion Top


Stink bugs excrete odorous bodily fluids as a defensive mechanism when threatened. If the toxic fluids get into the human eye, they can cause unexpected chemical burns or injury. Patients whose eyes come into contact with these bodily fluids should rinse their eyes thoroughly with plenty of water and immediately seek medical attention to avoid potential visual impairment.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors declare that there are no conflicts of interests of this paper.

 
  References Top

1.
Eger J. Stink bugs of economic importance in America North of Mexico. Fla Entomol 2002;85:297.  Back to cited text no. 1
    
2.
Ohira Y. Outbreak of the stink bugs attacking fruit trees in 2002. Plant Prot 2003;57:164-8.  Back to cited text no. 2
    
3.
Anderson BE, Miller JJ, Adams DR. Irritant contact dermatitis to the brown marmorated stink bug, Halyomorpha halys. Dermatitis 2012;23:170-2.  Back to cited text no. 3
    
4.
Jacobs S. Brown Marmorated Stink Bug. Pennsylvania State University, College of Agricultural Sciences, Department of Entomology; 2015. Available from: http://www.ento.psu.edu/extension/factsheets/brown-marmorated-stink-bug. [Last accessed on 2017 Jun 01].  Back to cited text no. 4
    
5.
Nielsen AL, Hamilton GC, Matadha D. Developmental rate estimation and life table analysis for Halyomorpha halys (Hemiptera: Pentatomidae). Environ Entomol 2008;37:348-55.  Back to cited text no. 5
    
6.
Durak D, Kalender Y. Fine structure and chemical analysis of the metathoracic scent gland secretion in Graphosoma lineatum (Linnaeus, 1758) (Heteroptera, Pentatomidae). C R Biol 2009;332:34-42.  Back to cited text no. 6
    
7.
Durak D, Kalender Y. Structure and chemical analysis of the metathoracic scent glands of Carpocoris fuscispinus (Boheman, 1851) (Heteroptera: Pentatomidae) from Turkey. Turk J Zool 2012;36:526-33.  Back to cited text no. 7
    
8.
Smith RM. The defensive secretion of Vitellus insularis (Heteroptera: Pentatomidae). N Z J Zool 1974;1:375-6.  Back to cited text no. 8
    
9.
Ho HY, Tsai RS, Chow YS. Chemical constituents of the defensive secretions of the metasternal gland of the stink bug, helopeltis fasciaticollis poppius (Hemiptera: Miridae) in Taiwan. Zool Stud 1995;34:211-4.  Back to cited text no. 9
    
10.
Henderson WG, Khalilian A, Han YJ, Greene JK, Degenhardt DC. Detecting stink bugs/damage in cotton utilizing a portable electronic nose. Comput Electron Agric 2010;70:157-62.  Back to cited text no. 10
    
11.
March J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. 6th ed. Hoboken, NJ: John Wiley & Sons; 2007.  Back to cited text no. 11
    
12.
Corey EJ, Gilman NW, Ganem B. New methods for the oxidation of aldehydes to carboxylic acids and esters. J Am Chem Soc 1968;90:5616-7.  Back to cited text no. 12
    
13.
Mead MD, Colby KA. Evaluation and initial management of patients with ocular and adnexal trauma. Principles and Practice of Ophthalmology. 2nd ed. Philadelphia, PA: W.B. Saunders; 1999.  Back to cited text no. 13
    
14.
McCulley J. Chemical injuries. The Cornea: Scientific Foundation and Clinical Practice. 2nd ed. Boston: Little, Brown; 1987. p. 527-42.  Back to cited text no. 14
    
15.
Herskovits TT, Gadegbeku B, Jaillet H. On the structural stability and solvent denaturation of proteins. I. Denaturation by the alcohols and glycols. J Biol Chem 1970;245:2588-98.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1]


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