Medical Entomology: Family Muscidae

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Questions and Answers

What is the scientific name for the house-fly?

Musca domestica

How many medically important species are there within the Family Muscidae?

3 (correct)

House-flies can transmit pathogens to humans through mechanical transmission.

True

The larva of the house-fly feeds on decomposing _____ material.

organic Signup and view all the answers

Match the following control methods with their categories:

Installing screening on windows = Physical and mechanical control Garbage being tightly closed = Environmental sanitation Residual spraying on indoor walls = Insecticidal control Signup and view all the answers

What is the wing venation difference between Muscina stabulans and house fly?

Vein 4 slightly bended toward vein 3 Signup and view all the answers

Stable flies, also known as biting-house flies, have four longitudinal stripes on their thorax.

True Signup and view all the answers

What do male and female stable flies feed on?

Blood Signup and view all the answers

What do stable fly maggots develop in?

Decaying organic matter (fermented mixture of straw, hay, urine, etc.) Signup and view all the answers

The late larval stage of Muscina stabulans are predaceous and feed on other __________ larvae.

fly Signup and view all the answers

Which species are associated with obligatory myiasis in humans?

Dermatobia hominis Signup and view all the answers

What is the medical importance of Lucilia serricata and Lucilia cuprina?

Both are associated with facultative myiasis and used in maggot therapy. Signup and view all the answers

Accidental myiasis is caused by larvae that must live on a living host for at least part of their lifecycle.

False Signup and view all the answers

Match the following genus with their characteristics:

Sarcophaga sp. = Large greyish flies with hairy and non-metallic appearance Wohlfahrtia sp. = Hairy flies smaller than Sarcophaga sp., abdomen with roundish spots Lucilia spp. = Metallic or coppery green adult flies, less bristly than bluebottle flies Signup and view all the answers

______ is the species causing accidental intestinal myiasis and is distributed in the Americas, Europe, Africa, and Asia.

Sarcophaga sp. Signup and view all the answers

What is the term for fly larvae infecting a living host such as on sores or wounds?

Facultative myiasis Signup and view all the answers

Which method of myiasis treatment involves applying liquid paraffin or petroleum jelly on the affected area to prevent larvae from accessing oxygen?

Occlusive and suffocation methods Signup and view all the answers

___________ myiasis is characterized by boil-like lesions.

Furuncular Signup and view all the answers

Tsetse flies belong to the Glossinidae family.

True Signup and view all the answers

Match the type of Glossina flies with their respective sizes:

Fusca flies = 10.5-15mm long Morsitans flies = 7.5-11mm long Palpalis flies = About 6.5mm long and the largest is 11mm Signup and view all the answers

Where are Chrysops commonly found?

low-lying marshy scrub areas or swampy woods, savannah, and grassland areas Signup and view all the answers

What are some of the medically important roles of Chrysops within the Tabanidae family? (Select all that apply)

Pest Signup and view all the answers

What is the vector responsible for transmitting Loa loa in monkey?

C.centurionis and C.langi Signup and view all the answers

_______ are used as attractant traps for local control of tabanid flies.

coloured screens coated with adhesive Signup and view all the answers

Study Notes

Suborder Cyclorrhapa

Family Muscidae includes house flies, greater house flies, and stable flies
4200 species and 170 genera in the family, with 3 medically important species:
- Musca domestica (house-fly)
- Muscina stabulans (greater house-fly)
- Stomoxy calcitrans (stable-fly)

Musca domestica (house-flies)

Morphology:
- Medium size, non-metallic, 6-9mm long
- Color varies from black to dark grey
- Four broad black longitudinal stripes on thorax
- Antennae with 3 segments and a prominent hair (arista) on the distal part
- Proboscis consists of labella and pseudotrachaea, adapted for sucking fluid
Life cycle:
- Lay eggs on decomposing materials (animal manure, poultry dung, carcasses, rubbish dumps, etc.)
- 75-150 eggs laid, with one female able to oviposit 5-10 times during its life
- Eggs are creamy white, banana-shaped, and hatch after 10-16 hours
- Larva (maggot) has cylindrical body, with hooks and cephalopharyngeal skeleton in the head
- Larva feed on decomposing organic material and measure 8-14mm long before becoming a pupa
- Pupa is barrel-shaped and adult fly emerges after 3-5 days
Medical importance:
- Can transmit pathogens to humans through contaminated feet, body hairs, and mouthparts
- Can transmit over 100 pathogens, including viruses, bacteria, protozoans, and helminths

Control of house-flies

Divided into three categories: physical and mechanical control, environmental sanitation, and insecticidal control
Physical and mechanical control:
- Installing screens on windows and other openings
- Using air currents or fans to keep flies from entering
- Using UV light traps
- Using sticky traps
Environmental sanitation:
- Minimizing breeding sites by tightly closing garbage and regularly collecting it
- Burning or burying garbage if not collected
Insecticidal control:
- Using larvicides, adulticides, residual sprays, insecticidal cords, and toxic baits
- Examples of insecticides used: malathion, pirimiphos-methyl, fenchlorophos, permethrin, cypermethrin, and deltamethrin

Muscina stabulans (greater house fly)

Distributed worldwide
Slightly larger than Musca domestica (7-10mm long)
Wing venation slightly different from house fly
Posterior spiracles of the maggot are circular
Late larval stage (maggots) are predaceous and feed on other fly larvae
Life cycle and medical importance similar to Musca domestica

Stomoxy calcitrans (stable fly)

Distributed worldwide
Also known as biting-house flies or dog flies
Adults have four longitudinal stripes on thorax
Forward-projecting, rigid proboscis
Wing venation similar to Muscina stabulans
Both male and female stable flies feed on blood
Mainly exophagic and can carry Dermatobia hominis eggs, a myiasis-producing fly
Control methods similar to house flies

Family Calliphoridae

Circular-seamed flies with aristate antennae
Medically important mainly due to its capability in producing myiasis
Two groups of calliphorids: non-metallic and metallic flies

Cordylobia anthropophaga (tumbu or mango fly)

Non-metallic fly
Distributed in Ethiopia, west, east, and south of Africa
Large flies (9-12mm long), dull to yellowish brown in color
Myiasis causing fly
Female lays 100-300 banana-shaped eggs in feces/urine contaminated areas
Larva can live 9-15 days without hosts
Larva attach to host or to clothing laid on ground
Larva burrow into skin, posterior spiracles exposed for breathing
Matured after 8-12 days and drop to the ground to pupate
Become adult after 8-15 days

Medical importance of Cordylobia anthropophaga

Larva cause boil-like (furuncular) swellings on the body
Infested site becomes sore, inflamed, hard, and exude fluids
Infestation usually with few larvae and up to 60 larvae
The larva head and body are in tissues
The spiracles are exposed for breathing

Control of Cordylobia anthropophaga

Removal of larvae by covering the site with liquid paraffin or Vaseline
Larva will emerge from the site to breathe, then it can be removed with forceps or by pressing
To prevent infection, avoid drying clothes on the ground where the larva can attach
Iron clothes to ensure no living larva on clothes

Metallic flies

Cochliomyia hominivorax (New world screwworm)
Chrysomya bezziana (Old world screwworm)
Lucilia spp. (greenbottle flies)
Calliphora spp. (bluebottle flies)

Cochliomyia hominivorax

Distributed in south USA, Mexico, Central America, Caribbeans, and north part of South America
Eradication program has successfully eradicated Cochliomyia from USA, Mexico, the Virgin Island, Curacao, and Central America (except Panama)
Obligatory parasite of living tissues (must have host to survive)

Chrysomya bezziana

Distributed in tropical Africa, west coast of Persian Gulf, Indian subcontinent, Southeast Asia, and Papua New Guinea
Obligatory parasite of living tissues (must have host to survive)### Life Cycle of Flies
After 2-4 days, larva reaches 3rd instars
After 4-10 days, larva matures and leaves the wound to drop to the ground and become a pupa
Adult emerges after 7-10 days (warm weather) or weeks to months (cooler climate)

Screwworm Flies

Family Calliphoridae
Cochliomyia hominivorax (New World screwworm)
Chrysomya bezziana (Old World screwworm)
Both cause obligatory myiasis
Larva has hooks on the mouthpart to hold onto host tissues

Medical Importance of Screwworms

Cause myiasis, which leads to damage, disfigurement, and excruciating pain
Infestation can occur in various parts of the body, including the face, causing impairment of speech
Infestation in the nasal area can affect the mouth palate

Treatment of Myiasis

Must be treated immediately due to rapid development of larvae
Manual removal of maggots or larvae
Irrigation of wound sites with ethanol or chloroform mixed with vegetable oil
Ivermectin can be used to kill larvae
Surgery may be necessary for deeply embedded larvae

Control and Prevention of Screwworms

Use of topical repellents and proper clothing for personal protection
Maintain self-hygiene
Create barriers, such as house screening, to prevent flies from entering homes
Adopting housefly control methods is recommended
Eradicating screwworm flies using the sterile male technique has been successful in the USA and Mexico

Metallic Flies (Blowflies)

Family Calliphoridae
Cochliomyia spp. (New World screwworms)
Chrysomya spp. (Old World screwworms)
Lucilia spp. (greenbottle flies)
Calliphora spp. (bluebottle flies)

Lucilia spp. (Greenbottle Flies)

Adult are metallic or coppery green in color
Size: ~ 10mm long
Less bristly than bluebottle flies
Lucilia serricata is the most common species, occurring worldwide

Calliphora spp. (Bluebottle Flies)

Adult are dull metallic bluish or bluish black in color
Robust flies with a size of ~ 8-14mm long
Thorax has a more well-developed bristle than Lucilia spp.
Abdomen is more shiny than thorax

Medical Importance of Lucilia spp. and Calliphora spp.

Both are associated with facultative myiasis
Attracted to foul-smelling wounds and ulcerations
Used in maggot therapy

Oestridae (Bot Flies)

Subfamily Cuterebrinae contains 57 species that cause obligatory myiasis in animals such as rodents, monkeys, and livestock
Dermatobia hominis causes myiasis in humans
Life cycle of Dermatobia hominis

Medical Importance of Oestridae

Cause myiasis, which induces an inflammatory response
Characteristic lesion is a painful and swollen skin known as cutaneous myiasis
Larva can often be seen at the center of the pore
Patients may report a sense of movement within the lesion

Treatment of Myiasis Caused by Oestridae

Surgical removal of the larva is the most common mode of treatment
Manual extraction can be performed if the larva is visible
Petroleum jelly can be used to induce hypoxia in the larva, causing it to migrate to the surface

Prevention of Myiasis Caused by Oestridae

Limit exposure to flies, especially in tropical areas
Wear clothing that covers the extremities
Use mosquito netting when sleeping
Use insect repellent on exposed skin

Sarcophagidae (Flesh Flies)

Only two genera, Sarcophaga and Wohlfahrtia, are medically important
Cause myiasis and act as mechanical vectors for pathogens
Distributed worldwide

Sarcophaga spp.

Large greyish flies with hairy and non-metallic appearance
Thorax has 3 black longitudinal stripes
Abdomen has a chequer-board appearance
Female is larviparous, depositing ~ 30-60 larvae per batch
Larvae are laid on carcasses, feces, rotting food, human, and wounds

Wohlfahrtia spp.

Adults are hairy flies with a smaller size (8-15mm) than Sarcophaga spp.
Appearance is greyish with prominent black lines on the thorax
Abdomen has roundish lateral spots and triangular shape markings along the midline
Adult female is larviparous, depositing 120-170 larvae in several batches

Medical Importance of Sarcophagidae

Cause myiasis, which leads to discomfort and pain
Species of Sarcophaga and Wohlfahrtia are distributed in the Americas, Europe, Africa, and Asia

Myiasis

Invasion of organs and tissues of living humans or other vertebrate animals by fly larvae
Types of myiasis: accidental, obligatory, and facultative
Treatment of myiasis: occlusive and suffocation methods, surgery, medication
Prevention of myiasis: use of insect repellent, maintenance of high levels of hygiene, ironing of clothes, and covering wounds### Glossina sp: The Life Cycle
After mating and taking a blood meal, a single egg completes maturation in one of the two ovaries and passes down the common oviduct into the uterus, where it is fertilized by sperm from the paired spermathecae.
The egg hatches within the uterus after 3-4 days into a larva, which receives all its nutrients from secretions from milk glands.
The larval development takes about 9 days, during which the larva goes through three instars.
The female selects shaded sites for larviposition, and about 15 minutes after the 3rd instar larval skin contracts and hardens to form a puparium, in which the larva pupates.
The puparial period is about 4-5 weeks.

Adult Behaviour

Adult flies feed depending on host availability, taking blood meals every 2-3 days in ideal conditions or every 10 days in cool, humid conditions.
Feeding is restricted during the daytime, and vision, as well as olfactory cues emanating from host breath and urine, are important in host location.
Adult flies are particularly attracted to dark moving objects.

Classification and Distribution

There are three groups of Glossina sp: Fusca (forest flies), Morsitans (savannah flies), and Palpalis (riverine and forest flies).
Fusca (forest flies) have 13 species, are 10.5-15mm long, and rarely feed on people or transmit sleeping sickness.
Morsitans (savannah flies) have 5 species, are 7.5-11mm long, and include vectors of sleeping sickness such as G. morsitans, G. pallidipes, and G. swynnertoni.
Palpalis (riverine and forest flies) have 9 species, are about 6.5mm long, and include vectors of sleeping sickness such as G. palpalis, G. fuscipes, and G. tachinoides.

Transmission of Trypanosomiasis

There are approximately 30,000 new cases of trypanosomiasis per year, with an estimated 400,000 new cases per year and 55,000 deaths.
The disease occurs in 36 African countries, with a patchy distribution.
There are two subspecies of trypanosomes causing human sleeping sickness: T. brucei gambiense and T. brucei rhodesiense (zoonosis), which are morphologically undistinguishable but different in clinical symptoms.
Important vectors of trypanosomiasis include G. palpalis, G. fuscipes, G. tachinoides, G. morsitans, and G. pallidipes.

Control of Tsetse Flies

Control methods target adult flies.
Culling of reservoir hosts, such as bovids, wild pigs, reptiles, and birds, is one method.
Destruction of surrounding vegetation is another method.
Insecticidal control involves spraying insecticides such as endosulfan, permethrin, deltamethrin, and cypermethrin onto vegetation, which remains effective for about 2-3 months.
ULV aerial insecticidal spraying requires re-spraying 5-6 times at 12-18-day intervals.
Spraying or dipping cattle with pyrethroid insecticides reduces the number of human trypanosomiasis cases.

Family Tabanidae (Horse Flies)

Tabanidae is a family of medium to large biting flies, comprising 4300 species and subspecies, and 133 genera.
Important genera include Tabanus (some known as greenhead), Haematopota (clegs and stout), and Chrysops (deer flies).
Tabanidae have been incriminated in the spread of anthrax and tularaemia and might be involved in the transmission of Lyme disease.

Chrysops sp (Deer Flies)

Chrysops are robust and heavily built, medium-sized flies (6-12mm).
They have iridescent eyes, commonly with spots of red, green, or purple.
Their wings are partially held over the abdomen in an open scissor-like fashion, with one or more brownish transverse bands.
The abdomen is blackish with orange or yellow patches or bands.
Antennae are the best feature to differentiate Chrysops from other Tabanids.
Female Tabanidae have stout and adapted mouthparts for biting, which hang down from the head.

Life Cycle of Chrysops sp

Eggs are laid in a single large mass (lozenge-shaped pattern) on the underside of objects, firmly glued in an upright position.
Eggs hatch after 4-14 days, and the wriggling larvae drop down onto the underlying mud or water.
Larvae are cylindrical, creamy white, brown, or greenish in colour, and have darkish pigmentation near the borders of the segments.
Chrysops larvae are mainly scavengers, feeding on detritus and organic matter.
Larval development takes about 1-2 years, with 10-16 instars.
Pupae are partially buried in mud or soil, in an upright position, with a distinctively curved body and large ear-shaped spiracles on the cephalothorax.

Medically Important Species in Tabanidae Family

Chrysops sp is the only genus in Tabanidae family that transmits Loa loa nematode to humans when blood feeding.
C. silaceus and C. dimidiatus are the main vectors of Loa loa in humans.
Other medically important species include C. distinctipennis, C. longicornis, C. centurionis, and C. langi.

Geographical Distribution of Loasis in Africa

Loasis is present in many African countries, with a patchy distribution.

Control of Horse Flies

Control of larvae is difficult due to unknown breeding sites.
Practical measures to control tabanid flies include efficient drainage of larval habitats, local control using attractant traps, and personal protection using insect repellents.

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Description

Learn about the morphology, life cycle, and medical importance of the Family Muscidae, including house flies, greater house flies, and stable flies. Understand control methods and their significance in medical entomology.