Keywords
diptera - ear diseases - larva - myiasis - parasites - sarcophagidae
Introduction
The word myiasis was first used by Hope, in 1840,[1] to refer to a parasitic disease caused by certain fly larvae during a particular
stage of their development when they feed on animal and human tissues. The geographic
distribution of the condition is almost exclusively limited to hot, tropical areas,
and its etiological agent varies from one region to another. Depending on the affected
organ, myiasis can be classified in cutaneous, enteric, ophthalmic, nasopharyngeal,
urogenital, oral and, as in our case, the less common otic myiasis. This article presents
a specific systematic review of the published literature on otic myiasis.
Review of the Literature
Methodology
A systematic review of the literature was made in June of 2016 on five different databases
(Medline, Embase, Cochrane Database of Systematic Reviews, LILACS and RedALyC). To
widen the sensitivity of the search, we used free terms; [Supplementary Material 1] (available online only) lists the search terms as well as the search constructs
for the different databases. We conducted a systematic review by following the guidelines
of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA)[2] ([Supplementary Material 2]). No limits were applied for age, year of publication, or language. Articles without
an abstract were excluded. The titles and summary lists were evaluated by two researchers
simultaneously to evaluate exclusion criteria: those that were clearly irrelevant,
as well as those focused on therapeutic treatment for larvae, non-human animal studies,
forensics, entomologic studies, or patients with risk factors such as recent surgical
wounds, cancer or ulcers. Information from the full-text remaining articles was collected
in a predesigned Excel spreadsheet [Supplementary Material 3]. The quality of the publications was assessed using the Joanna Briggs Institute
scale for case series,[2] and the Center for Evidence-Based Management (CEBMa) scale for individual case report
studies.[3]
Results
From the 272 initial studies ([Fig. 1]),[4] 82 of them were selected for full text review, 29 of which could not be found (23
of these were published between 1918 and 1994). After a second exclusion analysis,
6 articles were rejected for being considered irrelevant, and 7 more for failing to
meet the quality criteria. The remaining 40 studies reported 63 cases from 24 countries
(Argentina, Australia, Belize, Canada, Colombia, Costa Rica, Cuba, Dominican Republic,
Germany, India, Iran, Italy, Malaysia, Morocco, Nigeria, Paraguay, Poland, Rumania,
Saudi Arabia, South Korea, Spain, Thailand, Turkey, and United States). [Table 1]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
[30]
[31]
[32]
[33]
[34]
[35]
[36]
[37]
[38]
[39]
[40]
[41]
[42]
[43]
[44] summarizes the information from these articles ([Supplementary Material 4]).
Table 1
Characteristics of patients with otomyiasis
|
Reference
|
Country
|
n
|
Age
|
Gender
|
Clinical characteristics
|
Etiologic agent
|
|
[5]
|
Turkey
|
6
|
2–7 yr
|
3 M, 3F
|
_
|
Wohlfahrtia magnifica
|
|
[6]
|
Colombia
|
2
|
33, 23 yr
|
M, M
|
Drug addiction, otologic surgery in childhood due to otitis media
|
_
|
|
[7]
|
Malaysia
|
1
|
2 d
|
M
|
_
|
Sarcophagidae
|
|
[8]
|
Turkey
|
1
|
8 yr
|
M
|
Chronic otitis media
|
W. magnifica
|
|
[9]
|
Turkey
|
1
|
37 yr
|
M
|
Previous otomyiasis
|
W. magnifica
|
|
[10]
|
Saudi Arabia
|
1
|
12 yr
|
M
|
−
|
W. magnifica
|
|
[11]
|
Cuba
|
1
|
55 d
|
_
|
_
|
Calliphoridae phaenicia
|
|
[12]
|
Costa Rica
|
1
|
9 yr
|
M
|
Chronic otitis media
|
Cochliomyia hominivorax
|
|
[13]
|
Spain
|
1
|
55 yr
|
M
|
Alcoholic
|
C. phaenicia
|
|
[14]
|
Spain
|
1
|
5 mth
|
M
|
−
|
W. magnific
|
|
[15]
|
Turkey
|
1
|
12 d
|
F
|
Jaundice, thyroid dysgenesis
|
Lucilia sericata
|
|
[16]
|
Poland
|
2
|
44, 57 yr
|
F, M
|
Carcinoma of middle ear
|
L. sericata
|
|
[17]
|
Thailand
|
1
|
5 d
|
_
|
−
|
Parasarcophaga (Liosarcophaga) dux (Thomson)
|
|
[18]
|
South Korea
|
1
|
54 yr
|
M
|
−
|
L. sericata
|
|
[19]
|
USA
|
1
|
7 wk
|
M
|
_
|
Calliphoridae
|
|
[20]
|
Canada
|
1
|
60 yr
|
M
|
_
|
L. sericata
|
|
[21]
|
Spain
|
1
|
65 yr
|
F
|
−
|
C. bezziana
|
|
[22]
|
Dominican Republic
|
1
|
44 yr
|
F
|
−
|
−
|
|
[23]
|
India
|
1
|
3 yr
|
F
|
Otitis chronic media and mental retardation
|
Musca domestica
|
|
[24]
|
Turkey
|
1
|
57 yr
|
F
|
_
|
W. magnifica
|
|
[25]
|
Dominican Republic
|
1
|
26 yr
|
F
|
_
|
C. hominivorax
|
|
[26]
|
Malaysia
|
1
|
10 yr
|
F
|
_
|
Chrysomya megacephala
|
|
[27]
|
Italy
|
1
|
52 yr
|
F
|
Mental retardation
|
Sarcophaga hemorrhoidalis.
|
|
[28]
|
Paraguay
|
1
|
28 yr
|
M
|
Otorrhea bilateral
|
_
|
|
[29]
|
Belize
|
1
|
_
|
_
|
_
|
C. hominivorax
|
|
[30]
|
Argentina
|
2
|
11, 9 yr
|
M, F
|
Chronic malnutrition
|
C. hominivorax
|
|
[31]
|
Australia
|
1
|
16 yr
|
M
|
Mental retardation
|
Sarcophaga
|
|
[32]
|
Paraguay
|
1
|
37 yr
|
M
|
_
|
C. hominivorax
|
|
[33]
|
Nigeria
|
1
|
4 mth
|
F
|
_
|
_
|
|
[34]
|
Romania
|
1
|
_
|
_
|
Previous petromastoidectomy
|
L. sericata
|
|
[35]
|
Italy
|
1
|
44 yr
|
M
|
Farmer, chronic otitis media
|
W. magnifica
|
|
[36]
|
Malaysia
|
1
|
46 yr
|
M
|
Mental retardation
|
C. bezziana
|
|
[37]
|
India
|
14
|
1–35 yr
|
_
|
Chronic otitis media, ulcer, otitis externa and perichondritis.
|
_
|
|
[38]
|
Iran
|
1
|
55 yr
|
M
|
_
|
C. bezziana
|
|
[39]
|
Morocco
|
3
|
5,12,14
|
_
|
Chronic otorrhea
|
W. magnifica
|
|
[40]
|
Turkey
|
1
|
31 yr
|
M
|
Radical mastoidectomy secondary to gunshot wound
|
W. magnifica
|
|
[41]
|
Germany
|
1
|
49 yr
|
M
|
Alzheimer and tetraplegia
|
Sarcophaga
|
|
[42]
|
Iran
|
1
|
62 yr
|
F
|
Pulmonary edema and decompensated heart failure
|
L. sericata
|
|
[43]
|
Turkey
|
1
|
5 yr
|
M
|
_
|
W. magnifica
|
|
[44]
|
Spain
|
1
|
2 yr
|
M
|
Accompanied parents in field work
|
W. magnifica
|
Abbreviations: d, days; F, female; M, male; mth, months; wk, weeks; yr, years.
Fig. 1 Prisma diagram of the search strategy.[4]
Of the 63 cases reported, 34 were men (62%) and 21 were women (in 8 cases, no gender
was reported). The ages ranged from 2 days to 65 years old, with an average of 26.
Chronic otitis media, previous otic surgical procedures, mental deficit, alcohol and
drugs use, sleeping outdoors, prostration, malnutrition, jaundice and previous episodes
of otomyiasis were predisposing factors. In 30 patients, no risk factors were mentioned.
As for the etiological agents, the parasite was identified in 44 cases, 23 corresponded
to the Sarcophagidae family, 20 to the Calliphoridae family, and 1 to the Oestridae. Eleven cases were reported in Latin America (2 in Argentina, 2 in Colombia, 2 in
the Dominican Republic, 2 in Paraguay and one each from Belize, Costa Rica, and Cuba);
7 of them informed the agent, which was always from the Calliphoridae family.
Complications were reported in 23 of the 63 cases, describing tympanic perforation,
chronic otitis media, temporal bone extension, cartilaginous destruction, cellulitis
and perichondritis. The use of extraction with clamp, either with or without anesthesia,
was reported, and, in some cases, with the aid of suction and complementary otic lavage
with different types of substances, such as saline, lidocaine, alcohol, and hydrogen
peroxide. In 39 cases, antibiotics were mentioned, topical, oral or parenteral.
Discussion
Myiasis is a relatively common public health problem in developing countries, mainly
in hot, tropical areas.[45] There are, however, no clinical practice guidelines for diagnosis or treatment of
this disease. Otomyiasis occurs when the female fly, perhaps attracted by bad odor,
deposits its larvae in the auditory meatus.[46] Chronic otitis media or others otic pathologies are, therefore, predisposing factors.
A recent review article, with 45 cases of otomyiasis,[47] considers that sanitary conditions play an important role, but other triggers are:
low socioeconomic status, swimming in stagnant waters, diabetes mellitus, alcoholism,
prostration and suppurative chronic otitis media. Our review shows chronic otitis
media as a main risk factor that favor larvae growth.
Taxonomic division establishes several families derived from the order Diptera: Oestridae, Calliphoridae and Sarcophagidae are the most important. The species Wohlfahrtia magnifica, which belongs to the latter family, is a must-type larva, meaning that it requires
living in a host tissue to complete its development. This species is the predominant
etiologic agent worldwide,[47] but Sarcophagidae is the predominant family in Europe, and in the Middle East. In Latin America, all
the cases that reported the larvae belonged to the Calliphoridae family.
After having diagnosed myiasis through physical examination and, in some cases, through
diagnostic images, the treatment must begin as soon as possible, including direct
or surgical extraction of the larva.[48] To achieve that goal, the literature shows different treatments, which include antiparasitic
therapy with oral ivermectin[49]
[50] or topic permethrin.[5] The occlusion of the lesion is used to force the larvae to exit, thus facilitating
its manual extraction; this can be done using olive oil or petroleum jelly. Another
popular treatment, commonly used in rural areas,[45] involves placing a piece of bacon to attract the larvae, as reported in the Villamizar
case.[6]
The treatment should also include extraction using alligator forceps under micro-otoscopy
vision, in some cases anesthesia, suction and ear washes with saline solution 0.9%.
Systemic antibiotic therapy is also used when there is chronic otitis media, as discussed
by Yuca et al[5] The location of the infection and its proximity to the brain are a concern, and
authors have discussed the risk of myiasic meningitis and eventually death of the
patient, but we did not find this complication reported in the literature.
Final Comments
Otomyiasis is a parasitic condition that tends to affect vulnerable subjects in tropical
countries. Improving personal care would reduce the risk. Training health providers
is important for early diagnosis and treatment.
