- Email: [email protected]
Ocular external myiasis. A series of cases due to larvae Oestrus ovis in Navarra, Spain
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
ARCHIVOS DE LA SOCIEDAD ESPAÑOLA DE OFTALMOLOGÍA www.elsevier.es/oftalmologia
Short communication
Ocular external myiasis. A series of cases due to larvae Oestrus ovis in Navarra, Spain夽 L. Tabuenca-del Barrio ∗ , M. Mozo-Cuadrado, A. Zubicoa-Eneriz, P. Plaza-Ramos Servicio de Oftalmología, Complejo Hospitalario de Navarra, Pamplona, Spain
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objective: To report a case series of external ophthalmomyiasis in a region of Spain together
Received 15 March 2018
with its common epidemiological factors and treatment.
Accepted 29 May 2018
Material and methods: A presentation is made of four clinical cases of patients with external
Available online 22 August 2018
ocular myiasis caused by Oestrus ovis larvae.
Keywords:
lar globe externally and/or internally, with the former being the most frequently found
Results: Ocular myiasis is a parasitic infection by larval stages of flies. It can affect the ocuOestrus ovis
condition. The organism that mainly affects the eyes is the O. ovis larvae.
Ophthalmomyiasis externa
Conclusion: Ocular external myiasis is a rare condition that occasionally can occur in
Parasitic infection
humans. In this case series, a common risk factor for infection is established: the previ-
Treatment
ous exposure to livestock and/or agricultural activity. An adequate diagnosis and treatment could avoid the transition from external to internal form, as well as its complications. ˜ S.L.U. on behalf of Sociedad Espanola ˜ © 2018 Published by Elsevier Espana, de Oftalmolog´ıa.
Miasis ocular externa. Serie de casos por larvas Oestrus ovis en Navarra r e s u m e n Palabras clave:
Objetivo: Presentamos una serie de casos de miasis ocular externa en nuestra región asocia-
Oestrus ovis
dos a unos factores epidemiológicos comunes. Nuestro objetivo es mejorar el conocimiento
Miasis ocular externa
acerca de su tratamiento.
Infección parasitaria
Material y métodos: Se muestran 4 casos clínicos de pacientes con miasis ocular externa
Tratamiento
causada por larvas del díptero Oestrus ovis. Resultados: La miasis ocular es una infección parasitaria por estados larvarios de moscas. Puede afectar al globo ocular de forma externa y/o interna, siendo más frecuente la externa. El organismo que con mayor frecuencia afecta al ojo es la larva de Oestrus ovis.
夽 Please cite this article as: Tabuenca-del Barrio L, Mozo-Cuadrado M, Zubicoa-Eneriz A, Plaza-Ramos P. Miasis ocular externa. Serie de casos por larvas Oestrus ovis en Navarra. Arch Soc Esp Oftalmol. 2018;93:567–570. ∗ Corresponding author. E-mail address: [email protected] (L. Tabuenca-del Barrio). ˜ S.L.U. on behalf of Sociedad Espanola ˜ 2173-5794/© 2018 Published by Elsevier Espana, de Oftalmolog´ıa.
568
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
Conclusión: La miasis ocular externa es una afección poco frecuente en humanos. En la serie de casos se establece un factor de riesgo común para la infección: la exposición a actividades ganaderas y/o agrícolas. Un adecuado tratamiento a tiempo puede evitar el paso de la forma externa a la interna, así como sus posibles complicaciones. ˜ S.L.U. en nombre de Sociedad Espanola ˜ de © 2018 Publicado por Elsevier Espana, Oftalmolog´ıa.
Introduction Myasis is a parasitic disease caused by the infestation of tissue and organs by larvae of flies. In humans, myasis can be found at the cutaneous and subcutaneous level, in facial cavities, in the gastrointestinal and genitourinary systems as well as in wounds. The most frequent location is the skin, with the ocular globe being an exceptional location. Within ocular compromise, the most frequent form is external or keratoconjunctival. Three families of diptera can cause said disease in humans: Oestridae, Calliphoridae and Sarcophagidae. Oestrus ovis, belonging to the Oestridae family is the most common cause of ocular myasis.1 This is an obliged parasite in nasal cavities and frontal sinuses of sheep which can accidentally cause infection in humans. The present article summarizes a series of cases exhibiting common epidemiological features related to O. ovis infection in humans, making reference to adequate therapeutic management thereof.
Fig. 1 – Extraction of Oestrus ovis larva in right eye conjunctival sac fundus with tweezers.
Clinic case reports Four clinic cases received by the Ophthalmological Emergency Dept. of the Navarra University Complex, in Pamplona, Spain, between March and September 2017. Case 1. Female, 39, with foreign body feeling in left eye after accidentally engaging ocular contact with the fly while working in an orchard. Visual acuity (VA) was 10/10. Slit lamp examination identified 9 white larvae with black cephalic portion measuring 1 mm long, traversing the ocular surface. The larvae were extracted with tweezers and surgical sponge after instillation of topical anesthetic. Upon the appearance of rhinological clinic the patient was referred for joint examination with the ENT Dept. without finding larvae in said area. Case 2. Male, 57, who visited due to foreign body feeling in right eye while working at an agricultural farm. VA was 8/10. Biomicroscopy revealed white, 1 mm long larvae with similar characteristics to those described for case 1 rapidly moving over the ocular surface. After application of topical anesthesia, 19 larvae were extracted (Fig. 1). Case 3. Male, 20, who visited due to foreign body feeling in right eye after contact with the fly while watching a bull run. VA was 10/10. Anterior pole examination revealed the presence of 4 larvae measuring 1 mm long with similar appearance in size and characteristics with the previous cases, that were extracted with the same procedure (Fig. 2).
Fig. 2 – Oestrus ovis larva in contact with right eye half-moon fold.
Case 4. Male, 39, who visited due to foreign body feeling in right eye after performing agricultural work. Biomicroscopy revealed 4 larvae compatible with O. ovis in conjunctival sac fundus. These were withdrawn with tweezers after instillation of topical anesthetic (Fig. 3). Samples of all 4 cases were referred to the Microbiology Dept. for confirming the pathogen. Tobramycin was administered topically at 1 mg/ml and topical dexamethasone 3 mg/ml 4 times a day during 7 days as treatment for irritative conjunctivitis secondary to the mechanical extraction of the larvae as well as prophylactic antibiotic treatment. In addition, antiparasitic treatment is established with a single dose of ivermectin at a rate of 200 mcg/kg.
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
Fig. 3 – Oestrus ovis larva on tweezers, with more larvae in right eye conjunctival sac fundus.
Discussion O. ovis, also known as “nose worm” is a Diptera species of the Oestridae family that produces myasis in sheep and goats. It is widely distributed throughout the world and exhibits greater prevalence in regions with humid and warm climates. The adult fly, similar to a bee, has a lifecycle of up to 10 days and flies very quickly when approaching the nose of sheep to deposit its eggs. Adult females deposit larvae in larval state 1 (L1) in the nasal orifices of cattle, producing rhinitis. The larvae invade the frontal sinuses and grow to states L2 and L3, feeding on mucus and exudates which could produce sinusitis. In the L3 state they return to the nasal fossa and are expelled through sneezing, continuing the development on the ground until reaching the adult stage.2 Occasionally, it has been observed that larvae identified in L1 are able to produce zoonosis. In what concerns ocular compromise in humans, the fly accidentally establishes contact with the ocular globe, depositing larvae on its surface. Ocular myasis is a rare occurrence. In Spain, it is more frequent in males during spring and summer, matching the reproductive cycle of the flies. There are 2 forms of compromise, i.e., external or superficial which is more frequent, and internal or deep compromise that accounts for only 5% of cases. These parasites measure 1 mm length, and typically are white with black hooks anchored in the cephalic region. The most frequent symptoms are foreign body feeling, pain and inflammation due to dotted keratitis, conjunctivitis and small conjunctival hemorrhages produced by said hooks.3 In some cases, the larvae are able to penetrate the sclera and house in the subretinal space, and could even enter the vitreous humor, causing endophthalmitis and diminished visual acuity. For the above reasons, it is important to conduct a full posterior pole examination.1,4 In the present case series and in accordance with the literature, epidemiological factors exhibit a clear association between the appearance of the disease and exposure to cattle raising and/or agricultural activities. To reach the
569
diagnostic it is necessary to measure visual acuity and to conduct an exhaustive examination of the anterior and posterior poles, in addition to adequate anamnesis that includes said exposure antecedent. Compromise is unilateral in the majority of cases, with marked conjunctival hyperemia. Treatment of the external form consists in mechanical extraction of the larvae by means of tweezers and slit lamp. The application of topical anesthesia could be useful to facilitate this task as well as to immobilize the parasite, which is not always the case. Eyelids must be everted to facilitate a thorough search. It is advisable to attempt extraction at different times during the same visit to enable the appearance of larvae in difficult areas such as conjunctival sac fundus. There is no specific treatment but it is convenient to administer topical antibiotics (quinolones or aminoglycosides) and a topical anti-inflammatory (NSAID or corticoids) after extraction in order to improve symptoms and prevent bacterian overinfection. The antiparasitic treatment is conducted with a single dose of oral ivermectin at a ratio of 200 mcg/kg, that eradicates possible residual larvae and diminishes morbidity, although this is not a routine indication for said drug.5,6 In addition, clinic follow-up is recommendable to diagnose possible complications such as internal forms of the disease or involvement of other systems.
Conclusion O. ovis is the species that causes ocular myasis in the authors’ country in particular and generally throughout the world with greater frequency. The epidemiology of the disease involves the necessity of conducting anamnesis because the history of exposure to cattle or agriculture in rural environments is virtually a constant and could point to the diagnostic. Health intervention in cattle is the most efficient measure to prevent infections by said parasite as it involves a direct intervention on its natural habitat.
Conflict of interest No conflict of interest was declared by the authors.
references
1. Manal Z, Abdellatifl M, Hesham M, Elmazar F, Amna B. Oestrus ovis as a cause of red eye in Aljabal Algharbi Libya. Middle East Afr J Ophthalmol. 2011;18:305–8. 2. Sante L, Hernández-Porto M, Tinguaro V, Lecuona M. Oftalmomiasis y miasis nasal por Oestrus ovis en paciente residente en las Islas Canarias con características epidemiológicas poco frecuentes. Enferm Infecc Microbiol Clin. 2017;35:461–2.
570
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
3. Anane S, Hssine B. La myiase conjonctivale humaine à Oestrus ovis dans le sud tunisien. Soc Pathol Exot. 2010;103:299–304. 4. Vatsal P, Jyotirmay B, Vaijayanthi K, Debmalya D, Vishal R. Bilateral ocular myiasis interna caused by botfly (Oestrus ovis): a case report. Ocular Immunol Inflamm. 2011;19:444–7.
5. Rodriguez-Morales A. Enfermedades olvidadas: miasis. RPMESP. 2006;23:143–4. 6. Ribeiro F, Pereira C, Alves A, Marcon M. Treatment of human cavitary myasis with oral ivermectin. Rev Bras Otorrinolaringol. 2011;67:755–61.
ARCHIVOS DE LA SOCIEDAD ESPAÑOLA DE OFTALMOLOGÍA www.elsevier.es/oftalmologia
Short communication
Ocular external myiasis. A series of cases due to larvae Oestrus ovis in Navarra, Spain夽 L. Tabuenca-del Barrio ∗ , M. Mozo-Cuadrado, A. Zubicoa-Eneriz, P. Plaza-Ramos Servicio de Oftalmología, Complejo Hospitalario de Navarra, Pamplona, Spain
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objective: To report a case series of external ophthalmomyiasis in a region of Spain together
Received 15 March 2018
with its common epidemiological factors and treatment.
Accepted 29 May 2018
Material and methods: A presentation is made of four clinical cases of patients with external
Available online 22 August 2018
ocular myiasis caused by Oestrus ovis larvae.
Keywords:
lar globe externally and/or internally, with the former being the most frequently found
Results: Ocular myiasis is a parasitic infection by larval stages of flies. It can affect the ocuOestrus ovis
condition. The organism that mainly affects the eyes is the O. ovis larvae.
Ophthalmomyiasis externa
Conclusion: Ocular external myiasis is a rare condition that occasionally can occur in
Parasitic infection
humans. In this case series, a common risk factor for infection is established: the previ-
Treatment
ous exposure to livestock and/or agricultural activity. An adequate diagnosis and treatment could avoid the transition from external to internal form, as well as its complications. ˜ S.L.U. on behalf of Sociedad Espanola ˜ © 2018 Published by Elsevier Espana, de Oftalmolog´ıa.
Miasis ocular externa. Serie de casos por larvas Oestrus ovis en Navarra r e s u m e n Palabras clave:
Objetivo: Presentamos una serie de casos de miasis ocular externa en nuestra región asocia-
Oestrus ovis
dos a unos factores epidemiológicos comunes. Nuestro objetivo es mejorar el conocimiento
Miasis ocular externa
acerca de su tratamiento.
Infección parasitaria
Material y métodos: Se muestran 4 casos clínicos de pacientes con miasis ocular externa
Tratamiento
causada por larvas del díptero Oestrus ovis. Resultados: La miasis ocular es una infección parasitaria por estados larvarios de moscas. Puede afectar al globo ocular de forma externa y/o interna, siendo más frecuente la externa. El organismo que con mayor frecuencia afecta al ojo es la larva de Oestrus ovis.
夽 Please cite this article as: Tabuenca-del Barrio L, Mozo-Cuadrado M, Zubicoa-Eneriz A, Plaza-Ramos P. Miasis ocular externa. Serie de casos por larvas Oestrus ovis en Navarra. Arch Soc Esp Oftalmol. 2018;93:567–570. ∗ Corresponding author. E-mail address: [email protected] (L. Tabuenca-del Barrio). ˜ S.L.U. on behalf of Sociedad Espanola ˜ 2173-5794/© 2018 Published by Elsevier Espana, de Oftalmolog´ıa.
568
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
Conclusión: La miasis ocular externa es una afección poco frecuente en humanos. En la serie de casos se establece un factor de riesgo común para la infección: la exposición a actividades ganaderas y/o agrícolas. Un adecuado tratamiento a tiempo puede evitar el paso de la forma externa a la interna, así como sus posibles complicaciones. ˜ S.L.U. en nombre de Sociedad Espanola ˜ de © 2018 Publicado por Elsevier Espana, Oftalmolog´ıa.
Introduction Myasis is a parasitic disease caused by the infestation of tissue and organs by larvae of flies. In humans, myasis can be found at the cutaneous and subcutaneous level, in facial cavities, in the gastrointestinal and genitourinary systems as well as in wounds. The most frequent location is the skin, with the ocular globe being an exceptional location. Within ocular compromise, the most frequent form is external or keratoconjunctival. Three families of diptera can cause said disease in humans: Oestridae, Calliphoridae and Sarcophagidae. Oestrus ovis, belonging to the Oestridae family is the most common cause of ocular myasis.1 This is an obliged parasite in nasal cavities and frontal sinuses of sheep which can accidentally cause infection in humans. The present article summarizes a series of cases exhibiting common epidemiological features related to O. ovis infection in humans, making reference to adequate therapeutic management thereof.
Fig. 1 – Extraction of Oestrus ovis larva in right eye conjunctival sac fundus with tweezers.
Clinic case reports Four clinic cases received by the Ophthalmological Emergency Dept. of the Navarra University Complex, in Pamplona, Spain, between March and September 2017. Case 1. Female, 39, with foreign body feeling in left eye after accidentally engaging ocular contact with the fly while working in an orchard. Visual acuity (VA) was 10/10. Slit lamp examination identified 9 white larvae with black cephalic portion measuring 1 mm long, traversing the ocular surface. The larvae were extracted with tweezers and surgical sponge after instillation of topical anesthetic. Upon the appearance of rhinological clinic the patient was referred for joint examination with the ENT Dept. without finding larvae in said area. Case 2. Male, 57, who visited due to foreign body feeling in right eye while working at an agricultural farm. VA was 8/10. Biomicroscopy revealed white, 1 mm long larvae with similar characteristics to those described for case 1 rapidly moving over the ocular surface. After application of topical anesthesia, 19 larvae were extracted (Fig. 1). Case 3. Male, 20, who visited due to foreign body feeling in right eye after contact with the fly while watching a bull run. VA was 10/10. Anterior pole examination revealed the presence of 4 larvae measuring 1 mm long with similar appearance in size and characteristics with the previous cases, that were extracted with the same procedure (Fig. 2).
Fig. 2 – Oestrus ovis larva in contact with right eye half-moon fold.
Case 4. Male, 39, who visited due to foreign body feeling in right eye after performing agricultural work. Biomicroscopy revealed 4 larvae compatible with O. ovis in conjunctival sac fundus. These were withdrawn with tweezers after instillation of topical anesthetic (Fig. 3). Samples of all 4 cases were referred to the Microbiology Dept. for confirming the pathogen. Tobramycin was administered topically at 1 mg/ml and topical dexamethasone 3 mg/ml 4 times a day during 7 days as treatment for irritative conjunctivitis secondary to the mechanical extraction of the larvae as well as prophylactic antibiotic treatment. In addition, antiparasitic treatment is established with a single dose of ivermectin at a rate of 200 mcg/kg.
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
Fig. 3 – Oestrus ovis larva on tweezers, with more larvae in right eye conjunctival sac fundus.
Discussion O. ovis, also known as “nose worm” is a Diptera species of the Oestridae family that produces myasis in sheep and goats. It is widely distributed throughout the world and exhibits greater prevalence in regions with humid and warm climates. The adult fly, similar to a bee, has a lifecycle of up to 10 days and flies very quickly when approaching the nose of sheep to deposit its eggs. Adult females deposit larvae in larval state 1 (L1) in the nasal orifices of cattle, producing rhinitis. The larvae invade the frontal sinuses and grow to states L2 and L3, feeding on mucus and exudates which could produce sinusitis. In the L3 state they return to the nasal fossa and are expelled through sneezing, continuing the development on the ground until reaching the adult stage.2 Occasionally, it has been observed that larvae identified in L1 are able to produce zoonosis. In what concerns ocular compromise in humans, the fly accidentally establishes contact with the ocular globe, depositing larvae on its surface. Ocular myasis is a rare occurrence. In Spain, it is more frequent in males during spring and summer, matching the reproductive cycle of the flies. There are 2 forms of compromise, i.e., external or superficial which is more frequent, and internal or deep compromise that accounts for only 5% of cases. These parasites measure 1 mm length, and typically are white with black hooks anchored in the cephalic region. The most frequent symptoms are foreign body feeling, pain and inflammation due to dotted keratitis, conjunctivitis and small conjunctival hemorrhages produced by said hooks.3 In some cases, the larvae are able to penetrate the sclera and house in the subretinal space, and could even enter the vitreous humor, causing endophthalmitis and diminished visual acuity. For the above reasons, it is important to conduct a full posterior pole examination.1,4 In the present case series and in accordance with the literature, epidemiological factors exhibit a clear association between the appearance of the disease and exposure to cattle raising and/or agricultural activities. To reach the
569
diagnostic it is necessary to measure visual acuity and to conduct an exhaustive examination of the anterior and posterior poles, in addition to adequate anamnesis that includes said exposure antecedent. Compromise is unilateral in the majority of cases, with marked conjunctival hyperemia. Treatment of the external form consists in mechanical extraction of the larvae by means of tweezers and slit lamp. The application of topical anesthesia could be useful to facilitate this task as well as to immobilize the parasite, which is not always the case. Eyelids must be everted to facilitate a thorough search. It is advisable to attempt extraction at different times during the same visit to enable the appearance of larvae in difficult areas such as conjunctival sac fundus. There is no specific treatment but it is convenient to administer topical antibiotics (quinolones or aminoglycosides) and a topical anti-inflammatory (NSAID or corticoids) after extraction in order to improve symptoms and prevent bacterian overinfection. The antiparasitic treatment is conducted with a single dose of oral ivermectin at a ratio of 200 mcg/kg, that eradicates possible residual larvae and diminishes morbidity, although this is not a routine indication for said drug.5,6 In addition, clinic follow-up is recommendable to diagnose possible complications such as internal forms of the disease or involvement of other systems.
Conclusion O. ovis is the species that causes ocular myasis in the authors’ country in particular and generally throughout the world with greater frequency. The epidemiology of the disease involves the necessity of conducting anamnesis because the history of exposure to cattle or agriculture in rural environments is virtually a constant and could point to the diagnostic. Health intervention in cattle is the most efficient measure to prevent infections by said parasite as it involves a direct intervention on its natural habitat.
Conflict of interest No conflict of interest was declared by the authors.
references
1. Manal Z, Abdellatifl M, Hesham M, Elmazar F, Amna B. Oestrus ovis as a cause of red eye in Aljabal Algharbi Libya. Middle East Afr J Ophthalmol. 2011;18:305–8. 2. Sante L, Hernández-Porto M, Tinguaro V, Lecuona M. Oftalmomiasis y miasis nasal por Oestrus ovis en paciente residente en las Islas Canarias con características epidemiológicas poco frecuentes. Enferm Infecc Microbiol Clin. 2017;35:461–2.
570
a r c h s o c e s p o f t a l m o l . 2 0 1 8;9 3(1 1):567–570
3. Anane S, Hssine B. La myiase conjonctivale humaine à Oestrus ovis dans le sud tunisien. Soc Pathol Exot. 2010;103:299–304. 4. Vatsal P, Jyotirmay B, Vaijayanthi K, Debmalya D, Vishal R. Bilateral ocular myiasis interna caused by botfly (Oestrus ovis): a case report. Ocular Immunol Inflamm. 2011;19:444–7.
5. Rodriguez-Morales A. Enfermedades olvidadas: miasis. RPMESP. 2006;23:143–4. 6. Ribeiro F, Pereira C, Alves A, Marcon M. Treatment of human cavitary myasis with oral ivermectin. Rev Bras Otorrinolaringol. 2011;67:755–61.