Cordylobia
anthropophaga, the mango fly, tumbu fly, tumbafly, putzi fly or skin maggot fly is a species of blow-flycommon in East and Central Africa. It is a parasite
of largemammals (including humans) during its
larval stage.
Anthropophaga
has been endemic in the subtropics of Africafor more than 135 years and is a common cause of myiasisin humans in the region.
Its
specific epithet anthropophaga derives from the Greekword anthropophagos, "human eater".
The
mode of infection by the Cayor Worm
DoctorsRodhain and Bequaert conclude, from their observations inthe Congo Free State, that Cordylobia anthropophagalays its eggs on the ground. The larvae, knowngenerally as Cayor Worms, crawl over the soil until
theycome in contact with man or a mammal,
penetrate the skinand lie in the subcutaneous
tissue, causing the formation oftumors. On
reaching full growth, the larvae leave the host,fall to the ground, bury themselves and there - pupate.
Thisfly is said to be the most common cause of human oranimal myiasis in tropical Africa, from Senegal to Natal.
Inthe region of Lower Katanga where these
investigationswere made, dogs appeared to be
the principal hosts,although Cordylobia
larvae were found also in guinea-pigs,a
monkey and two white men.
The
larvae are alwayslocalized on those parts of the hosts
which come inimmediate contact with the
soil." (Ann. Soc. Entom. DeBelgique, Iv,
pp. 192–197, 1911) summary translation inEntomological
News. 1911 Vol. xxii: 467.
History
of Discovery
The
larvae of the tumbu fly, Cordylobia anthropophaga,were first described in Senegal in 1862, and Blanchard
firstdescribed the adult and gave it its name
in 1893. In 1903,Grunbert placed the tumbu
fly in a new genus, Cordylobia.
Life
cycle
Female
tumbu flies deposit 100-300 eggs in sandy soiloften contaminated with animal feces. The hatched larvaecan remain viable in the soil for 9–15 days until
they needto find a host for development.
If
a larva finds a host, itwill penetrate the
skin and take 8–12 days developingthrough
three larval stages before it reaches the pre-pupalstage. It will then leave the host, drop to the ground,
buryitself, and pupate. It then becomes an
adult fly able toreproduce and begin the cycle
all over again.
Clinical
Presentation in Humans
Successful
penetrations in humans will result in furuncular(boil-like) myiasis, typically on the backs of arms or
aboutthe waist, lower back, or buttocks.
Anthropophaga
rarely causes severe problems, and mainly causes cutaneous myiasis. Geary et
al. describe the presentation of cutaneous myiasis caused by the tumbu fly
thus, "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 lesions
develop into a furuncle. The furuncle's aperture opens, permitting fluids
containing blood and waste products of the maggot to drain."
Transmission
Female
tumbu flies lay their eggs in soil contaminated withfeces or urine or on damp clothing or bed linens. Dampclothing hanging to dry makes for a perfect spot. The
larvaehatch in 2–3 days and attach to
unbroken skin andpenetrate the skin,
producing swelling.[7] If the larvae hatchin
soil, any disturbance of the soil causes them to wriggle tothe surface to penetrate the skin of the host.
Reservoir
and Vector
A
natural reservoir is defined as an organism that canharbor a pathogen indefinitely with no ill effects.
AlthoughC. anthropophaga larvae can cause ill
effects for animalhosts, because we are
talking about myiasis in humans, wewill
consider any animal hosts as reservoirs.
Many
animals are hosts of C. anthropophaga. The dog isthe most common domestic host and several species ofwild rats are the preferred field hosts. Domestic
fowl aredead-end hosts, meaning that the
larvae cannot developwhen they enter the
tissue of a fowl.
Humans
are in fact accidental hosts, which mean thattumbu fly larvae do not usually infect humans. We as aspecies are not necessary for the transmission cycle
of theFly.
A
vector is an organism that carries the parasites (thelarvae) from one host to another. The tumbu fly itself is
thevector in a loose sense, because the
female deposits theeggs in soil or on damp
cloth, where the larvae can hatchand attach
to human or animal skin.
Diagnostics
Cutaneous
myiasis caused by the tumbu fly should besuspected when a patient who has just spent time in Africapresents with ulcers or boil-like sores. Definitive
diagnosisis only possible when the larvae are
found. They should beremoved and allowed to
develop into adult flies foridentification
purposes.
Treatment
In
cases of cutaneous myiasis, the larvae are most oftenremoved without an incision. Applying petroleum jelly to
theskin blocks the breathing hole and cuts
off the larva’s airsupply. This pushes the
maggot to the surface of the skin asit
searches for air. The larva can then easily be extractedfrom the skin. If this does not work, local anesthetic can
beadministered and an incision made to
extract the maggot.
Another
treatment discussed in the March 2014 Journalof the American Medical Association is to inject acombination of anesthetic and epinephrine into the insect'schamber, thus expelling it hydraulically.
Patients
should be monitored for additional and subsequentlesions, as development does not occur in unison and somelarvae may take longer to reach the pre-pupal stage.
Toprevent bacterial infection after removal
of the larvae,antibiotics can be
administered.
Epidemiology
C.
anthropophaga is the most common cause of myiasis inAfrica (WHO).
The
tumbu fly is endemic to the tropical regions of Africa,south of the Sahara desert. Myiasis caused by C.anthropophaga is the most common cause of myiasis inAfrica but can be seen worldwide because of air
travel, ashuman movements carry infestation
outside endemic areas.
Public
Health and Prevention Strategies
The
fly commonly infects humans by laying its eggs on wetclothes, left out to dry. The eggs hatch in one to threedays and the larvae (who can survive without a host
for upto 15 days) then burrow into the skin
when the clothes areworn. A prevention method
is to iron all clothes, includingunderwear,
which will kill the eggs/larvae.