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Bites and Sting
Exotic myiasis with Lund's fly (Cordylobia rodhaini)
After a four-week holiday in East Africa, a woman was diagnosed with
furuncular myiasis: a third-instar larva of the fly Cordylobia
rodhaini (Lund's fly) was found in a skin lesion. This is the first
report of exotic myiasis and importation of this species of fly into
Australia, and reflects the increasing risk of introducing exotic
flies of public health and veterinary importance to Australia.
Merilyn J Geary, Bernard J Hudson, Richard C Russell and Andrew Hardy
MJA 1999; 171: 654-655
Introduction -
Clinical record -
Discussion -
Acknowledgements -
References -
Authors' details
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| | Introduction |
Myiasis is the invasion of living tissue by the larval stage (maggot)
of flies.1 Australia has some species
of flies that produce facultative and accidental myiasis in
humans,2 but in other countries,
particularly in Africa and South America, there are flies with
zoonotic obligate myiasis that infest humans. With more frequent
international travel, there is an increasing risk of infestations of
these species being brought into Australia.
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Clinical record |
A 57-year-old woman presented to her general practitioner (A H) with a
painful, discharging lesion on the outer aspect of her right thigh
three days after returning to Australia from a safari vacation in East
Africa.
She was referred to a specialist (B J H), who diagnosed furuncular
myiasis after seeing "something moving" at the base of the lesion.
After occlusion with petroleum jelly, a fly larva protruded from the
lesion and was removed with forceps (Figure 1a). The lesion healed uneventfully over the following two
weeks.
The patient had left Australia one month earlier and spent most of the
safari trip camping. She travelled in four countries -- Kenya,
Tanzania, Uganda and Zimbabwe (see Map). For the final 10 days she
stayed at a private residence on a ranch between Bulawayo and Victoria
Falls in Zimbabwe. She noticed the lesion two days after arriving at
the ranch. It gradually developed over the next 10 days, becoming
moderately painful and discharging.
Although it was not possible to determine exactly where the
infestation was acquired, from the species involved and the time
required for its stage of development the contact probably occurred
shortly before or shortly after arrival at the ranch in Zimbabwe.
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Discussion |
Genus Cordylobia
The genus Cordylobia contains three species, C.
anthropophaga, C. rodhaini and C.
ruandae.1 Larvae of these flies are
parasites of various mammals, particularly rodents. C.
anthropophaga (the Tumbu fly of sub-Saharan Africa), and
occasionally C. rodhaini, also parasitise
humans.3,4 Cordylobia is
confined to the African continent, with C. rodhaini
associated with tropical Africa, especially areas of rainforest
from Senegal, through Central Africa, to Angola and Zimbabwe (see
area marked on Map).
The adult flies of C. rodhaini are large and robust, with a
non-metallic red-brown to black abdomen and yellow coloration on the
thorax and head. Adult flies feed on rotting fruits, vegetables and
faeces, and are more abundant throughout the wet season, and most
active in the early morning and evening. The life cycle of C.
rodhaini is shown in Figure 2.
Public health concerns
Although importation of exotic myiasis-causing flies into
Australia is not common, several species of obligatory fly parasites
enter this country each year in the skin of overseas travellers
(unpublished data).2,5-10
The most common exotic species of myiasis fly imported to Australia in
humans is the human botfly (Dermatobia hominis) (Figure 1b), found in travellers returning
from South and Central America (unpublished data). Others include
the Tumbu fly (C. anthropophaga) (Africa), and the New World
screw-worm fly (Cochliomyia hominivorax) (Central and
South America). All are of medical and public health concern, and
some, such as Chrysomya bezziana from Africa, South-East
Asia and Papua New Guinea, and C. hominivorax, are of critical
veterinary importance,8,11 and threaten local
livestock industries.
Travellers to the tropics and general practitioners in Australia
should be aware of the potential for skin infestation by fly larvae,
and local health professionals can assist quarantine, agriculture
and other interested bodies to monitor the importation of these
medically important insects.
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Acknowledgements | |
The photographs were taken by Mr Stephen Doggett of the Department of
Medical Entomology, Institute of Clinical Pathology and Medical
Research (ICPMR), Westmead Hospital.
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References |
- Zumpt F. Myiasis in man and animals in the old world. London:
Butterworths, 1965: xi-xii, 75-77.
-
Lee DJ. Human myiasis in Australia. Med J Aust 1968; 1:
170-173.
-
Bertram DS. A note upon myiasis due to the larvae of Cordylobia
Rodhaini Gedoelst. Ann Trop Med Parasitol 1938; 32:
431-435.
-
Scholten ThH, Hicks RJ. Myiasis by Cordylobia rodhaini
contracted in Africa and diagnosed in Canada. Can J Public
Health 1973; 64: 488-489.
-
Field AS. Myiasis in an Australian abroad. Med J Aust 1981;
1: 581-582.
-
Moorehouse DE. Exotic parasitic infections in Australia
[editorial]. Med J Aust 1983; 2: 592-593.
-
Prociv P. The risk from exotic myiasis in Australia [letter].
Med J Aust 1989; 150: 722-723.
-
Searson J, Sanders L, Davis G, et al. Screw-worm fly myiasis in an
overseas traveller -- case report. Commun Dis Intell 1992;
16: 239-240.
-
Rubel DM, Walder BR, Jopp-McKay A, Rosen R. Dermal myiasis in an
Australian traveller. Australas J Dermatol 1993; 34: 45-47.
-
Levot G. Interception of larvae of an exotic fly pest in skin
lesions on Australian travellers. Commun Dis Intell 1994;
18: 229-230.
-
Norris KR. Myiasis in humans. Med J Aust 1989; 150:
235-237.
(Received 17 Jun, accepted 27 Oct, 1999)
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Authors' details | |
Department of Medical Entomology, University of Sydney, and
Institute of Clinical Pathology and Medical Research, Westmead
Hospital, Westmead, NSW.
Merilyn J Geary, DipAppSc, Senior Technical Officer.
Richard C Russell, MSc, PhD, Director.
Microbiology Department, Royal North Shore Hospital, Sydney, NSW.
Bernard J Hudson, FRACP, FRCPA, Staff Specialist.
Manning Medical Practice, Woollahra, NSW.
Andrew Hardy, MB BS, General Practitioner.
Correspondence: Professor R C Russell, Department of Medical
Entomology, Westmead Hospital, Westmead, NSW 2145.
RichardRATicpmr.wsahs.nsw.gov.au
©MJA 1999
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Figure 1a: A third-instar larva of Cordylobia rodhaini (size about 20mm, bar=1mm), infecting a woman just returned from East Africa. Myiasis caused by this species has not previously been recorded in a patient in Australia. The third instar of C. rodhaini is readily recognisable, with a scattered covering of spines, longer than those of the related fly larva C. anthropophaga and not organised in rows as in that species.
1,3
Figure 1b: A third-instar larva of Dermatobia hominis (bar=1mm), which occurs in Central and South America, and is the myiasis fly species that most commonly infects travellers returning to Australia.
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 Figure 2: Description of lesion: At the site of penetration, a red papule forms and gradually enlarges. At first the host may experience only intermittent, slight itching, but pain develops and increases
in frequency and intensity as the lesion develops into a furuncle. The furuncle's aperture opens, permitting fluids containing blood and waste products of the maggot to drain.
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