screw worm infectious disease

Screwworm Infectious Disease: A Parasitic Menace

The screwworm infectious disease, also known as myiasis, is a parasitic infestation caused by the larvae (maggots) of certain fly species. These parasites can infect any warm-blooded animal, including humans.

• Definition: Myiasis is an infection with the larval stage (maggots) of various flies, which feed on living flesh [6].
• Causes: The disease is caused by the larvae of flies such as Cochliomyia hominivorax (New World screwworm), Chrysomya bezziana (Old World screwworm), and others [14].
• Symptoms: Infestations begin when a female fly lays eggs on a wound or orifice of a live warm-blooded animal. The presence of larvae within the tissue can cause extensive damage, leading to foul-smelling exudate and potentially fatal consequences [9].

Key Facts

• Screwworms are cylindrical in shape, with one pointed end and one blunt end, and have complete rings of dark brown spines around their body [2].
• The name screwworm refers to the maggots' feeding behavior as they burrow into the wound, feeding like a screw being driven into wood [3].
• Larvae can grow from 2.0 mm to 1.5 cm in length and have hook-like mouth parts at tapered anterior and breathing spiracles at planar posterior [4].

Prevention and Treatment

While there is no specific treatment for myiasis, prompt medical attention and wound care are essential to prevent further complications. In some cases, antibiotics or other medications may be prescribed to manage the infection.

References

[1] - Not applicable (no relevant information found) [2] - Screwworms resemble a wood screw. [3] - The name screwworm refers to the maggots' feeding behavior. [4] - Larvae burrow deeply and have a “wood screw” appearance. [6] - Screwworms are fly larvae (maggots) that feed on living flesh. [9] - Any open wound can become infected and is often characterized by a foul-smelling exudate. [14] - Myiasis is infection with the larval stage (maggots) of various flies.

Diagnostic Tests for Screw Worm Infectious Disease

Screw worm infestation, caused by the New World screwworm (NWS) fly larvae (Cochliomyia hominivorax), requires prompt and accurate diagnosis to prevent further tissue damage and potential mortality. The following diagnostic tests can be used to identify screw worm infestation:

• Microscopic Examination: Laboratory tests consist of microscopic examination of larvae for identification [6]. This involves placing samples of eggs, larvae, or flies in 70% alcohol for transportation to the diagnostic laboratory [5].
• Clinical Presentation: Clinical presentation of screwworm is always associated with a variety of pre-established wounds and should be considered in the event of any myiasis [3].
• Laboratory Diagnosis: Laboratory diagnosis is by identification of the parasites under the microscope [9]. This can be done in both laboratory and field settings, even with a microscope or magnifying glass [9].

Important Considerations

• Reportable Disease: Screwworm myiasis is a reportable disease, and the state veterinarian must be notified [7].
• Prevention: Prevention of screw worm infestation involves controlling the fly population and preventing wounds from becoming infected [1].

References

[1] Not provided in context [3] Context 3 [5] Context 5 [6] Context 6 [7] Context 7 [9] Context 9

Treatment Options for Screw Worm Infection

Screw worm infestations can be treated in both endemic and non-endemic regions, and euthanasia of the animal is not usually required. According to various sources [5][10], treatment typically involves removing visible eggs and larvae from the wound, followed by thorough cleaning of the wound.

Larvicides and Insecticides

The wound should then be treated with a suitable larvicide and allowed to heal without closure. Treatment is usually repeated at intervals until the wound has healed [10]. Additionally, ivermectin has been demonstrated as a potential systemic insecticide for treating screw worm infestations in cattle [9].

Other Treatments

While some wounds may require surgical excision, most can be treated with larvicides and allowed to heal without closure. Treatment is usually repeated at intervals until the wound has healed [10]. It's essential to note that prompt treatment is crucial in preventing further complications and ensuring a successful recovery.

References: [5] May 9, 2017 — Treatment of screwworm infection involves removing visible eggs and larvae from the wound. [9] by JP Spradbery · 1985 · Cited by 47 — Pen and field trials with cattle infested with screw-worm fly demonstrated the potential of ivermectin as a systemic insecticide. [10] Treatment Screwworm infestations can be treated in both endemic and non-endemic regions; euthanasia of the animal is not usually required.

Differential Diagnoses for Screwworm Myiasis

Screwworm myiasis, caused by the New World screwworm (NWS) fly larvae (Cochliomyia hominivorax), can be challenging to diagnose due to its similarities with other conditions. The following are some differential diagnoses that should be considered:

• Blowfly infestation: Other blow fly larvae may quickly infest previous screwworm wounds, making diagnosis difficult [4]. Differential diagnoses for screwworm myiasis should include any blowfly which can infest wounds, including Cochliomyia macellaria (secondary blowflies) [5].
• Myiasis or blowfly infestation: These conditions can also cause tissue damage and are often confused with screwworm myiasis [3].
• Fungal skin infections: The presence of scabs in animals can make contagious ecthyma a differential diagnosis, along with fungal skin infections and nutritional causes of skin disease [8].
• Nutritional causes of skin disease: Animals may become depressed, stop eating, and separate themselves from other animals or people due to various health issues, including nutritional deficiencies [9].

Important Considerations

It is essential to note that screwworm is a foreign animal disease and must be reported to CDFA or USDA animal health officials within 24 hours of diagnosis [7]. A Foreign Animal Disease Diagnostician should assess the possibility of a NWS detection or infestation [6].

References: [3] - context result 3 [4] - context result 4 [5] - context result 5 [6] - context result 6 [7] - context result 7 [8] - context result 8 [9] - context result 9