House Flies
Muscidae
Common housefly
Musca domestica (Family Muscidae)
Introduction
- can be vectors of helminths, faecal bacteria, protozoans
and viruses, resulting in the spread of enteric diseases (e.g. dysenteries
and typhoid) - 70 species of flies
Important Species
- The bazaar fly (Musca sorbens)
- The notoriously troublesome bush fly (M. vetustissima)
- The face fly (M. autumnalis)
Morphologies
- Medium-sized non-metallic flies about 6–9 mm long
- four rather broad black longitudinal stripes
- The mouth parts (proboscis) are specially adapted for
sucking up fluid or semifluid foods. - fine channels called
pseudotracheae through which fluids are sucked up - pulvilli, which are supplied with glandular hairs.
- sticky hairs enable the fly to adhere to very smooth surfaces
Life Cycle
- feed on food of humans, rotting vegetables, carcasses,
excreta and vomit – in fact almost any organic material - Female Musca domestica lay their eggs on decomposing materials
- The eggs are creamy-white, 1–1.2 mm long, and distinctly
concave dorsally - Egg hatch after only 10–16 hours, but this period is longer in
cool weather - Larvae, known as maggots, have a small head followed by an 11-
segmented cylindrical body - The puparial stage lasts about 3–5days in warm weather but 7–14 days during cooler periods
Medical Importance
can transmit viruses of:
1) polio
2) Coxsackie and infectious
hepatitis
3) rickettsiae of Q fever (Coxiella burnetii)
4) bacteria such as:
- anthrax
- Campylobacter
- cholera (Vibrio cholerae)
- Shigella and Salmonella
- Escherichia coli
- Staphylococcus aureus
- spirochaetes of yaws (Treponemapertenue)
- protozoans including Entamoeba,
Cryptosporidium and Giardia
5) Helminths
Control Measures
- Physical and mechanical control
- Environmental sanitation
- Insecticidal control
Flies and Myiasis
- Flies are dirty insects with two wings (Diptera)
- Myiasis is defined as an infestation by fly larvae (maggots)
Life Cycle (Habitat)
- Obligatory
- Facultative
- Accidental or Pseudomyiasis
Life Cycle (Habitat)
- Obligatory
- Facultative
- Accidental or Pseudomyiasis
Medical Importance
- Biological
- Sites of infection
Types of Myiasis based on sites of infestation:
A. Cutaneous
B. Intestinal
C. Urogenital
D. Ophthalmic, Aural, Nasal and Oral Myiasis
Cutaneous Myiasis
Fly eggs hatch on
injured wounds (traumatic myiasis), burn wounds and ulcers, especially if these wounds are exposed.
Intestinal Myiasis
This is also called pseudomyiasis. It occurs as a result of accidentally swallowing maggots in food
stuff like fruits (fruit flies) and cheese (cheese skipper. Occasionally, this condition is accompanied by intestinal symptoms like abdominal pain and diarrhea.
Urogenital Myiasis
Eggs are laid under the prepuce or vaginal folds and will hatch into maggots. Maggots may occasionally
be found in the urine or vagina
Ophthalmic, Aural, Nasal, Oral Myiasis
Any exposed organ such eyes, ears or nose can be infested.
Pathogenesis
- deposit their eggs or larvae in the wounds or body orifices (ear, nose) when there is discharge (bloody/serous).
-The larvae penetrate in the tissue
- The wound develops an offensive odor and a foul-smelling liquid oozes out
Treatment for Myiasis
- With ethanol or chloroform mixed with vegetable oil.
- Ocular myiasis, and delicate surgery may be needed to remove the larvae.
-covering the hole in the swelling with medicinal liquid paraffin.
- Maggot Debridement Therapy
