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)