Agents of Myiasis

Agents of myiasis

All agents of myiasis are flies and members of the order Diptera, which consists of those insects with only a single pair of functional wings. Myiasis-causing flies can be separated according to whether their larvae are obligate, facultative, or accidental parasites (defined below) ^4-7.

Kingdom Animalia

Phylum Arthropoda

Subphylum Uniramia

Class Insecta

Order Diptera

Specific myiasis (Obligate parasites)

These flies require a living host for completion of larval development. Most of the obligate parasites come from the families Oestridae, Calliphoridae, or Sarcophagidae. The Oestridae family contains about 150 sepcies, all of which are obligate parasites. Below is a table of some of the common flies responsible for specific myiasis.

Family	Taxonomic name	Common name
Cuterebridae	Dermatobia hominis	Human botfly
Caliphoridae	Cordylobia anthropophaga	Tumbu fly
Oestridae	Oestrus ovis	Sheep botfly
Oestridae	Hypoderma spp.	Cattle botfly, Ox warble
Caliphoridae	Cochliomyia hominivorax	New World screwworm
Caliphoridae	Chrysomya bezziana	Old World screwworm
Sarcophagidae	Wohlfahrtia magnifica	N/A
Sarcophagidae	Wohlfahrtia vigil	N/A

Cochliomyia hominovorax, the New World screwworm

(Image source: http://www.cals.ncsu.edu:8050/course/ent425/text19/screwworm.html)

Dermatobia hominis, the human botfly

(Image source: http://espanol.geocities.com/ueb2001/Resumen/entomologia/muscidae.htm)

Semispecific myiasis (Facultative parasites)

These flies usually lay eggs in decomposing animal tissue or vegetable matter, though live hosts can also serve as hosts. Myiasis would usually be found in already existing wounds, and blood and foul discharge often serve as an attractant for the insects.

Most of the flies responsible for semispecific myiasis come from the family Sarcophagidae. Common examples are listed in the following table.

Family	Genus	Common name
Sarcophagidae	Lucilia	Green bottle flies
Sarcophagidae	Cochliomyia	Blue bottle flies
Sarcophagidae	Calliphora	Blowflies
Sarcophagidae	Sarcophaga	Flesh flies

Lucilia spp. (Image source: http://www.entomologieforensique.ch/page1.htm)

Accidental myiasis (Accidental parasites)

Accidental myiasis is caused by flies that do not require a host for larval development and do not opportunistically seek wounded/dead tissue. Eggs or larvae can be inhaled or ingested with food; it is also possible for eggs to enter the body through openings in the genitourinary tract.

Many species of flies can produce accidental myiasis. Some notable ones are:

· Musca domestica (Family Muscidae), known as the common housefly

· Fannia spp. (Family Muscidae), known as latrine flies

· Eristalis tenax (Family Syrphidae), known for its rat-tailed maggot

Musca domestica (Image source: http://www.bugbustersgsy.com/housefly.htm)

Common name