Efficient spin-up of Earth System Models usingsequence acceleration
Screwworm infestation
1.
2. Screwworm
Screwworm infestation is a disease where fly larvae (maggots) feed on living flesh. They infest
all mammals and rarely birds.
In the New World Screwworm is known as (Cochliomyia hominivorax) and in the old world it is
known as Chrysomya bezziana. But the disease is called Myiasis.
3. Screwworm
Causative Agent: Caused by the larvae of Cochliomyia hominivorax the common name
for this fly is blow fly.
Aetiological Agent: Cochliomyia hominivorax, Is found in the Western Hemisphere,
primarily in tropical areas of South America and Caribbean Islands.
4. Pathogenesis / life cycle
Life cycle
The screwworm fly life cycle includes the eggs, larvae, pupae and adults. The life cycle can be
completed in less than 20 days under ideal environmental conditions.
Eggs
100–200 are laid in rafts beside wounds.
Larvae (maggots)
Hatch about 12 hours after laid.
Enter living tissue around wounds.
Create cavernous, foul smelling lesions up to 10–12cm in diameter.
Feed on host tissue until mature—about 5–7 days.
When mature they leave the wound and fall to the ground.
5. Continue...
Pupate
Pupate for 2–60 days before the flies emerge.
Do not survive temperatures below freezing.
Adult
Free flying.
Prefer warm humid environments.
Optimum temperature range is 20–30ºC.
7. Clinical Signs
Signs of infestation of maggots in animals include:
visible maggots in wounds
constant licking of the wound
restlessness
fever
lethargy
infected, smelly and bleeding wounds, sometimes with pus and maggots emerging
hard and swollen navels
Common areas for screwworm strike include the:
head and surrounding area
brisket
genital area
navel.
8. Diagnosis
In order to diagnosis screwworm infestation properly one must look first for the signs:
Screwworm often exists in wounds that already exists, such as castration, dehorning, branding,
shearing, wire cuts, sore mouth in sheep, and shedding of the velvet in deer. Navels of newborn
mammals.
Bloody discharge from the infested wounds
Malodor
Discomfort
Decreased feed intake
Decreased milk production
The diagnosis of screwworm is based on the identification of the agent which is difficult
especially as non screwworm species may be present. Larvae and adult flies should be sent to
specialist entomologists for identification.
9. Treatment/ Correction
Remove the larva from the wound with a
tweezer then flush the area with dilute
iodine solution. Then you would do
wound care twice daily until heal with
gentian violet solution and wound
powder which are topical antibiotics.
10. Prevention/Control:
Prevention/ Control:
Washing the area or the environment
where the animal is to reduce order
which may attract blow fly.
The use of asuntal powder 1% and
sipermetrin can be use to control
screwworm.
$547.77 JMD
Spraying the navel of a calf with ectoline spray.
11. Reference
Veterinary Division - animal health programs. (n.d.). Retrieved March 26, 2021, from
https://www.ncagr.gov/vet/Factsheets/screwworm.htm
Disease information. (n.d.). Retrieved March 26, 2021, from
https://www.cfsph.iastate.edu/diseaseinfo/disease/?disease=screwworm-myiasis
Screwworm flies. (2017, January 20). Retrieved March 26, 2021, from
https://www.iaea.org/topics/sterile-insect-technique/screwworm-
flies#:~:text=The%20larvae%20burrow%20through%20the,increasing%20need%20
for%20agricultural%20production.