What are the other Names for this Condition? (Also known as/Synonyms)

• Myiasis at Pin-Site

What is Pin-Site Myiasis? (Definition/Background Information)

• Myiasis is primarily a skin disease caused by several species of parasitic fly larva (of taxonomic order Diptera). The fly larvae (maggots) cause disease in humans and other vertebrate animals by feeding on the tissues. The infection is usually characterized by a painful, itchy, boil-like skin lesion that contains the parasite within it
• Pin-Site Myiasis is an uncommon complication wherein myiasis develops at sites of metal pins, which are used to hold fractured bones. The pins are usually used as external fixators to temporarily hold broken bones in place, especially in open fractures
• A fly larva infestation at such locations may be aided by factors such as improper dressing, poor hygiene and neglect of pin entry sites, old age, and/or mental illnesses. The causative agent of Pin-Site Myiasis is identified as the New World screw-worm fly (Cochliomyia hominivorax), per available medical literature
• An early diagnosis and treatment of Pin-Site Myiasis is essential to avoid deep-seated infections and occurrence of septicemia. Management of the condition involves removal of all larvae followed by surgical debridement. In some cases, the holding pins may have to be removed and replaced after extracting larvae

Who gets Pin-Site Myiasis? (Age and Sex Distribution)

• Pin-Site Myiasis is mostly observed in elderly adults, although individuals of any age may be affected
• Both males and females are affected, and no gender preference is noted
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Pin-Site Myiasis? (Predisposing Factors)

The following factors may predispose individuals to Pin-Site Myiasis:

• Open fractures that require the use of needles, pins, and external fixators
• Surgical (pin) wound sites that are left uncared for and/or without proper dressing
• Advancing age
• Bedridden patients who cannot care for themselves
• Psychiatric illnesses
• Presence of co-morbidities such as hypertension or diabetes
• Any medical condition that decreases one’s immunity
• Open wounds that are neglected

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Pin-Site Myiasis? (Etiology)

• Pin-Site Myiasis is a parasitic infection that involves bone fracture fixator pin sites
• The condition is known to be caused by the New World screw-worm fly (Cochliomyia hominivorax), among others

The parasitic insects either lay eggs or deposit their larvae around open/fresh wounds of the pin sites. This is aided by conditions such as old age, improper care of the pin site, or poor mental health of the patient.

What are the Signs and Symptoms of Pin-Site Myiasis?

The signs and symptoms of Pin-Site Myiasis may vary from one individual to another and is based on the type of larva species, and the site of infection. At the pin site, the following may be noted:

• Open wound/ulcer that is aggravating and slowly increasing in size
• Increased redness, swelling, and bleeding is noted; pungent or foul-smelling discharge may be observed
• Individuals can sense movement of the larva within the wound
• Pain that may be severe

Additionally, systemic signs and symptoms, such as high-grade fever, chills, and muscle and joint pain may be noted.

How is Pin-Site Myiasis Diagnosed?

Pin-Site Myiasis is diagnosed on the basis of the following information:

• Complete physical examination and a thorough medical history evaluation (including history of recent surgeries, invasive procedures undergone, etc.)
• Assessment of signs and symptoms, including a visual examination of the lesion, if present
• Laboratory tests: Blood tests, such as complete blood count and peripheral blood smear
• Imaging studies, as necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Pin-Site Myiasis?

The complications of Pin-Site Myiasis may include:

• Secondary infection of the abscess; rupture of the abscess
• Cellulitis: Skin infection that involves the deeper skin tissues
• Hypereosinophilia and leukocytosis (increased white blood cells)
• Severe inflammatory response to dead larvae or parts of larvae, especially during its removal
• Blood poisoning (septicemia), which can be life-threatening

How is Pin-Site Myiasis Treated?

Pin-Site Myiasis that arise at surgical (pin) sites are managed with a combination of medication and surgical care. The treatment may involve the following measures:

• Surgical debridement of dead or necrotic tissue after removal of all larvae
• The larvae may be immobilized through oil and chloroform and then extracted
• Deep lesions may be irrigated with antiseptic solutions
• The fixator pins may have to be removed, cleaned, and replaced
• Regular dressing changes and wound care, as needed
• Prescription oral medications (usually ivermectin), based on healthcare provider’s evaluation
• Broad-spectrum antibiotics, as needed

Examination and identification of the larva following removal is important.

How can Pin-Site Myiasis be Prevented?

Pin-Site Myiasis may be prevented by considering the following measures:

• Ensure clean and hygienic surroundings in healthcare settings
• Adherence to the best medical practices
• Ensure that surgical wounds are properly treated and dressed/covered
• Follow good pin-site care practices and guidelines
• Medical centers should provide fly screens on patient area doors, windows, and ventilators (including duct filters)
• Educate patients, patient caregivers, and visitors on basic hygiene, handwashing importance, and overall cleanliness

What is the Prognosis of Pin-Site Myiasis? (Outcomes/Resolutions)

• The prognosis of Pin-Site Myiasis is generally good when the infection is diagnosed and treated early
• However, delayed diagnosis/treatment may result in complications, including sepsis

Additional and Relevant Useful Information for Pin-Site Myiasis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/