Myiasis,e Pub

Myiasis Causing LarvaeMyiasis Causing Larvae

ByByDr. S. Samanta and Dr. O. K. Raina Dr. S. Samanta and Dr. O. K. Raina

Division of Parasitology, Division of Parasitology, Indian Veterinary Research Institute, Indian Veterinary Research Institute, Izatnagar, IndiaIzatnagar, India

Myiasis - Invasion of tissue by dipterous larvae

• Calliphoridae - bottle flies or blow flies, and screwworm flies

• Sarcophagidae - flesh flies• Gasterophilidae - horse bot• Hypodermatidae - cattle grub, warble or

heel fly• Oestridae - nose bot• Cuterebridae - emasculating fly, skin bot

Anecdote• The infestation of live human and vertebrate

animals with dipterous larvae, which at least for a certain period,feed on host dead or living tissue,liquid body substance,or ingested food

(Zumpt, 1965)

• A disease condition caused by invasion of living tissue of vertebrates by the dipterous fly larvae

(Hall &Wall, 1995)

• Huge economic losses to livestock, leather industries

Family - Calliphoridae

• Morphology - slightly larger than Musca, bright metallic color

• Pathology - Maggots may infect wounds or soiled wool or hair coat. If the area is not treated, healthy tissue is invaded

Genus-Lucilia

• L. cuprina, L. sericata, L. cesar, L. illustris.

• Primary Myiasis causing fly

• Eggs laid in carrion or decaying vegetable matter, diseased tissue or in wounds and hatch in 24 hours. After a week of feeding larvae drop to ground or crawl to a dry area and form puparium

Genus-Calliphora

• C. bezziana, C. megacephala, C. rufifacies.

• Primary Myiasis causing fly

• Eggs laid in carrion or decaying vegetable matter, diseased tissue or in wounds and hatch in 24 hours. After a week of feeding larvae drop to ground or crawl to a dry area and form puparium

Family-Sarcophagidae

• Flesh flies

• S. argyrostoma S. ruficornis

Family-OestridaeGenus- Gasterophilus

• Gastrophilus intestinalis - horse bot fly G. nasal is - throat bot fly G. haemorrhoidalis - nose bot fly

• Pathology - Adult flies annoy horses Heavy infestation may damage mucosa of mouth and stomach and may block the pyloris

Genus:- Hypoderma cattle grubs, ox warbles or heel flies

• Two different species, both belonging to the genus Hypoderma

– Hypoderma lineatum: Common Cattle Grub

– Hypoderma bovis: Northern Cattle Grub

• Members of Oestridae, a family of obligatory myiasis causing flies, with 166 spp of veterinary importance.

• Subfamily Hypodermatinae, whose

members are all cutaneous parasites

Genus: Oestrus- sheep bot

• Oestrus ovis

• Pathology - Heavy infestation can be fatal if there is penetration into the cranium

• Animals show great distress by sneezing and shaking of head, loss of appetite and a purulent discharge

Chronology• 1845- Scholechiasis

(Kirby & Spence)

• 1840-Myiasis (Hope)

• 1947-20 obligatory & 50 facultative myiasis causing fly spp. Enlisted

(James)

• 1965-Definition of myiasis (Zumpt)

• 1995- Definition of myiasis (Hall & Wall)

Key Players-Indian chapter• C.bezziana- main cause of myiasis in India

(Patton,1920)

• Entomology & Acarology for India. (Sen &

Fletcher)

• L.cuprina-responsible for 1.3% cases of myiasis in India.

(Joseph,1987)

• Antigenic characterization of 1st & 3rd instar immunogenic antigens of C.bezziana & C.megacephala. (Baidya,S.2003)

Brunt areas• Economic impacts

– Decreased milk production– Hide damage– Stress & injury from gadding– Weight gain changes– Immunosupression– Increased butchering costs

• Animal welfare concerns

• Human health impact

Financial losses• In Australia 3million sheep/yr.dies due to

blow-fly strike i.e, $200 million loss/yr (Brideoake,D.R.,1970-1976)

• Loss of $430 million/yr.to the sheep industry of Australia

(Spradbery, 1994)

• Loss of $10,000/yr.to the sheep industry of south Africa

Indian context• Around 48-52% cases of traumatic wounds are

infested with the maggots of myiasis causing flies

• Around 75% sheep were reported to be infested with nasal bot in central sheep breeding farm, Hissar

(Das-1986)

• There will be 10% increase in milk production, without any increase in no. of animals in Rajasthan if only the warbles can be controlled

Milk revenue losses• In 2003, average per cow milk production was

18749 lbs. At an average price of $.12/lb., that gives a value of about $2300 per cow per year

(USDA,2003)

• A dairy cow with an average parasite load produces 15-25% less milk per day than an uninfested cow, or 14000-15900 lbs./year

• That means a drop in revenue to $1700-$1900, a difference of $400-$600, plus treatment costs, per infested animal

(USDA,2003)

Hide damage losses• Percentage of all hides with insect damage in

1999: 2.4%

• Average value of a 1000 lb. steer hide in 2003: $57.02

• Percentage of total carcass value of hide in 2003: 5.67%

• Value lost due to presence of multiple brands or one rib brand in 2004: ~$25

(National cattleman’s beef asso. 2004)

Hide damage losses

Zoonotic impact• In western France, there were 31 cases of human infestation

between 1945 and 1965

• Although cattle grubs are highly host specific, there are many reports of accidental human myiasis, particularly in Eastern Europe

• Symptoms range from allergic reaction to “creeping myiasis” to ocular myiasis that can cause blindness to meningitis

(Boulard, 1997)

• In India 254 unidentified cases of myiasis was reported from E.N.T Dept, Rohtak hospital during 2yr. Period

(Singh et al.,1993)

Immuno-suppression

• Cattle infested with grubs are more susceptible to other pathogens, because of the effect of hypodermin A on white blood cells

• If infestation is not detected early, veterinary costs can be substantial for secondary problems

• Unfortunately, these costs are hard to quantify over production - who knows whether a cow would have gotten sick, infested or not?

Conventional control methods

• Squeezing or lancing of warbles

• Application of tars, oils, sulfurs & kerosene

• Rotenone ointments & washes

• Organochlorines and organophosphates

• Aldrin, dieldrin, & lindane

• Systemics: Ronnel, Crufomate, & kin

• Macrocyclic Lactones- Ivermectin

• Sterile Male Technique

• Genetically Impaired Female Technique