Perspective Chapter: Screwworm Wound Infection in Basal Cell Carcinoma Seen in a Resource-Limited Setting in Rural South Africa – Case Report and Literature Review

3.1 Presentation

We present a 75-year-old Caucasian male, known with basal cell carcinoma (BCC), whose main complaint was worsening pain and itchiness on his left shoulder, which had a cancerous lesion that was getting larger and forming a cavity. The onset of the complaints was 2 days before the presentation to the surgical outpatient department.

The patient was diagnosed with basal cell carcinoma (BCC) 20 years ago. He had a previous wide local excision (WLE) of some lesions. But more lesions appeared over the years in different areas of his body. He has multiple lesions all over his body, most notably on the chest, left shoulder, wrist, and back.

There is no positive history of cancer in the patient’s family. He has no known allergies and is an ex-smoker (he quit tobacco products >50 years ago) who occasionally consumes alcohol. His primary occupation is farming. He lives and works on his farm. The patient reported that one of his cows had a screwworm infestation and died following its consequences. As a caretaker, he was near the animal during its burial and the enclosure where the cow was kept about 2 weeks prior to his presentation.

On examination, the patient was acutely ill-looking, with a blood pressure (BP) of 120/70 mmHg, a heart rate of 80 beats/min, and an elevated temperature of 38.2°C. His general examination was unremarkable.

A focused skin examination revealed a 6x4 cm septic lesion on the left anterior aspect of the chest at about the midclavicular line extending to the anterior axillary line at the level of the second intercostal space extending to the third intercostal space. The skin on the back had two ulcerating non-septic lesions on the right parasternal area about the level of T5/6, measuring about 5x7 cm and a small 3x5 cm posteriorly at the left lumbar region. The left wrist lesion measured 3x4 cm and was characterised as a fungating lesion with no sign of sepsis. The left shoulder lesion measured 5x5 cm, an ulcerating and necrotic wound with screwworms in its cavity. The wound was foul smelling with purulent discharges and noted erythema at its edges. Figure 1 shows the initial image of the wound.

All other systems were reviewed, and no abnormalities were detected.

3.2 Management

The patient was admitted to the ward for further workup and prepared for theatre: WLE, debridement of his infected left shoulder and chest wounds, and removal of the left fungating wrist lesion. Consent was obtained for the procedure, and the patient was started on empiric antibiotics (co-amoxiclav 1 g per os 12hrly) and analgesia (paracetamol 1 g per os 6hrly, tramadol 50 mg per os 8hrly/as needed, and ibuprofen 400 mg per os 8hrly/as needed).

3.3 Investigations

Blood tests were done, and the laboratory results are summarised in Table 1. As part of the preparation for the operation, the patient was typed and screened, and a chest X-ray was done to assist the anaesthetists with assessing the patient’s ventilation capabilities.

3.4 Surgical intervention

The following day, he was taken to the theatre for a WLE, debridement, and biopsy of the wrist, septic chest, and shoulder lesion. Intra op, the wrist and chest lesions were debrided with no complications. The shoulder lesion was debrided with the removal of dead tissue and was found to have been infested by screwworms. The surgical team started to remove the screwworms mechanically; however, every time an attempt was made to pull them out, they dug further into the patient’s flesh. Diluted hydrogen peroxide was used to kill the worms and force them to the surface, but it seemed like they could withstand the solution and further burrowed into the patient’s muscle. Samples of the lesion and the few worms taken were collected and sent to the lab. The debridement was quite extensive in tracking the worms. However, a short distance from the humerus bone, the team opted to stop cutting away at the muscle bulk. It was still apparent that several worms were still lodged in his shoulder muscles while the incision was cleansed and bandaged. To prevent compromising the functionality of the limb, the surgical team opted not to pursue it further.

3.5 Outcome and follow up

Postoperatively (post-op), he continued the empirical antibiotics for 7 days. It is essential to mention that the patient self-medicated with ivermectin shortly after surgery, on day 0 and day 1 post-op. Acetic acid wash was added to the wound care regimen to kill the remaining screwworms. Day 3 post-op, no worms were seen in the wound, which was healing well. On day 6 post-op, the acetic acid wash was stopped, and the wound was dressed with betadine solution and collagenase clostridiopeptidase A/proteases topical dressing.

The patient’s reasoning for self-medicating with ivermectin was that he felt the worms burrowing through his flesh even after the surgery, causing immense pain. Being a farmer and having experienced first-hand, the remarkable efficacy of the drug in screwworms-infested livestock, and the horrors that follow if left untreated, he knew that it was essential for him to take ivermectin sooner rather than later. This decision was further reinforced by the fact that worms fell out of his wound the day after surgery (day one post-op), and the pain subsided. On day 3 post-op, he had no agony and no longer felt like worms were eating away at his flesh.

As his treating doctors did not prescribe ivermectin, his vitals and general condition were closely monitored for adverse drug effects. Until his discharge, neither negative symptoms nor signs were noted, and his vitals remained stable.

The Histology report of the samples collected is reported as follows.

Skin left upper arm: Infiltrative basal cell carcinoma with screwworms. Subacute inflammation involving the dermis and underlying subcutaneous tissue.

Skin left forearm: Invasive moderately differentiated keratinising squamous cell carcinoma (fully excised).

Skin left chest wall: Ulcerating basal cell carcinoma (incompletely excised).

The wounds continued to heal well, and on day 14, he returned to the theatre for debridement and split skin grafting (SSG) of his chest, wrist, and shoulder wounds. There were no complications, and the graft took well. Figure 2 shows the left shoulder on day 3 post-SSG.

On day 6, post-SSG, the patient was discharged with a referral to his attending dermatologist for the continued care of the basal cell lesions and to continue wound care at local clinics.

4.1 Introduction

The New World screwworm fly (NWS), Cochliomyia hominivorax (Coquerel), and the Old World screwworm (OWS), Chrysomya bezziana (Vileneuve), are obligate parasites of mammals during their larval stages. NWS and OWS are in the subfamily Chrysomyinae of the family Calliphoridae (blow flies) of the order Diptera (true flies) [6, 7].

Screwworms can infest all warm-blooded animals, as mentioned in the background. Many documented cases of screwworm myiasis have been reported in humans. The life-cycle duration of screwworms outside their host (in the pupae and adult stages) depends on the ambient temperature. Unlike most species of blowflies, adult female screwworms do not lay their eggs on carrion; instead, they deposit their eggs along the edges of wounds on living, injured mammals or at the openings of body orifices. Nearly any type of wound is appealing, whether it is natural (from fighting, predators, thorns, diseases, or bites from ticks and other insects) or man-made (from activities like shearing, branding, castrating, dehorning, docking, or ear-tagging).

Female screwworms place individual eggs in a single direction, resembling a tiled roof, and these eggs are firmly attached to the surface where they are laid. Within 12 to 24 hours after the eggs are deposited, larvae emerge and immediately begin feeding on the fluids from the wound and the underlying tissues. They burrow downward as a group into the wound in a characteristic screwworm manner. Infested wounds often emit a distinct odour that may not be easily detected by humans; this smell can be the first indication that at least one animal in a group is infested. A severe infestation left untreated may result in the host’s death [6].

4.2 Geographical distribution

The spread of screwworms is limited mainly by their inability to endure continuously cold weather; hence, they cannot typically survive over winter compared to temperate zones. They thrive in warm and humid environments [8].

NWS are primarily present in the western hemisphere, notably in South America and the Caribbean’s tropical and subtropical regions. Screwworms are also uncommon at elevations above 7000 feet. Due to eradication programs, these parasites have been eliminated from North and Central America, as well as Puerto Rico, the Virgin Islands, and Curaçao. To prevent screwworms from moving northward from South America, a sterile fly release program is maintained in the Darien Gap, located between Panama and Colombia. However, this barrier is occasionally breached, resulting in the discovery of screwworms in Panama. In Jamaica, an ongoing eradication program is in place. In 1988, New World Screwworms (NWS) were discovered in Libya but have since been eliminated there. Old World Screwworms (OWS) can be found in parts of Asia, much of tropical and sub-Saharan Africa, and certain Middle Eastern countries. OWS have never established themselves permanently in Europe, Australia, New Zealand, or the Western Hemisphere [9].

4.3 Transmission

Screwworm larvae are obligate parasites that rely exclusively on living animals for their lifecycle and survival. Wounds that are infested with screwworms often attract additional female screwworms, leading to multiple infestations being common. Humans can get screwworm infection by coming in close contact with infested livestock, and the adult female screwworms lay their eggs in open wounds or mucous membranes [6, 9].

Occasionally, OWS may also deposit their eggs on unbroken soft skin, particularly in the presence of blood or mucus on the surface. Upon hatching, the larvae penetrate the flesh, where they feed on living tissues and bodily fluids. Once hatched, the maggots, after feeding through their host’s flesh for two moults (5–7 days), the larvae leave the wound and fall to the ground and then burrow into the soil to pupate (turn into pupae) [6, 9].

4.4 Incubation period

Eggs hatch within 12 to 24 hours, but screwworm larvae are difficult to detect in wounds during the first 2 days [9].

4.5 Life cycle

The life cycle of C. hominivorax has been described in detail by Spradbery [10]. C. hominivorax females are attracted to hosts with wounds or moist openings, such as the navels of newborn animals, where they lay batches of up to 245 eggs. Eggs hatch within a few hours, and the larvae then enter the tissue, causing damage to the living cells. After three larval stages (instars), the mature larvae exit the wound after 6 to 7 days. They drop to the ground and burrow into the soil to form a puparium. Adults emerge subsequently, depending on ambient temperatures [6].

4.6 Morbidity and mortality

When ecological conditions are suitable, the morbidity caused by screwworms might be exceptionally high [11]. In some regions, the navel of practically every newborn animal may be infested with screwworms. Generally, a single egg deposit or a treated infestation is not lethal; nevertheless, smaller animals or those with subsequent illnesses may perish. Within 7 to 10 days, untreated wounds commonly develop numerous infections, which can be fatal. New World screwworms appear to cause more deaths than their Old World counterparts [9].

4.7 The economic burden of screwworms

The annual losses caused by screwworms in the South American hemisphere are estimated to be $3590 million, and annual losses in the Caribbean basin amount to an estimated $157 million. These numbers are pretty rough and theoretical and do not account for the significant losses in production due to death, particularly of newborn and young animals, lesser weight gains, higher labour costs, devaluation of hides, decreased milk yield, and other economic factors [8, 12].

Our literature survey revealed scanty information regarding the economic effects of screwworms on people. However, screwworm myiasis poses a significant threat to human health; it is estimated that over 330 million people live in regions where NWS is endemic. In most countries, the disease has been controlled by tight medical surveillance and treatment, but where surveillance is abandoned, the sickness poses a risk of reaching epidemic proportions [8, 12].

4.8 Risk factors

Some known risk factors associated with screwworm infestations in humans are as follows:

Gender: Several studies have shown that females were more commonly affected than males, which could be attributed to the post-menopausal syndrome in elderly females and that elderly females in poor socio-economic populations are often ignored [13].

Old age: Due to age-related circumstances such as being bedridden, wheelchair-bound, or crippled, suffering from several underlying illnesses, or being tube-fed, elderly adults may be at a higher risk for screwworm infections [14, 15].

Wound or Skin Lesions: Open wounds, such as surgical wounds, traumatic injuries, and chronic ulcers, provide an entry point for screwworm flies to deposit their eggs. Skin lesions, such as dermatitis or eczema, may also attract flies and increase the risk of infestation [14, 15, 16].

Underlying diseases: Individuals with underlying conditions, such as infections, age-related diseases, and chronic noninfectious diseases, may be at increased risk for screwworm infections. Open wounds and infections are the most recorded underlying conditions. Age-related diseases and noninfectious chronic diseases such as dementia, stroke, cancer, diabetes mellitus, and hypertension are also commonly recorded in elderly patients [14, 17].

Poor Hygiene and Living Conditions: Unsanitary living conditions, inadequate wound care, and poor personal hygiene practices can increase the risk of attracting screwworm flies. Living in rural or agricultural areas with exposure to livestock or domestic animals exposure can also contribute to the risk [14, 16, 17].

Inadequate Protection: Lack of protective measures, such as using insect repellents, wearing protective clothing, or utilising screens on windows and doors, can increase the likelihood of contact with screwworm flies and subsequent infestation [14].

Immunocompromised Status: Individuals with compromised immune systems, such as those with HIV/AIDS, undergoing chemotherapy, or taking immunosuppressive medications, may face a higher risk of developing screwworm infestations. Weakened immune responses can impair the body’s ability to control the infestation and prevent complications [14, 16].

Occupational Exposure: Certain occupations, such as farmers, veterinary professionals, or individuals working in outdoor environments with frequent contact with animals, may have a higher risk of screwworm infestations due to increased exposure to fly populations [16].

Travel to Endemic Areas: Travelling to regions where screwworm flies are endemic, such as parts of South America, Central America, or Africa, can increase the risk of encountering the flies and acquiring an infestation [14]. The number of tourists travelling across international borders rose from 537 million in 1995 to 1.13 billion in 2014. Myiasis is one of the top five most prevalent travel-related skin illnesses, accounting for 3.5 to 9% of all skin infections [18].

It is important to note that susceptibility to screwworm infestations may vary, and not all individuals with the risk factors will develop an infection. Implementing preventive measures, such as maintaining good hygiene practices, protecting open wounds, and avoiding contact with flies, can help reduce the risk of screwworm infestations in humans.

The clinical features of screwworm infections in humans vary depending on the site of infestation and the degree of damage. The larvae destroy living tissues and cause deep, painful, ulcerative lesions associated with bleeding and a serosanguinous purulent discharge [19]. Secondary infections, fever, weight loss, and inflammation may occur as a result. A massive initial infestation or repeated attacks can lead to significant soft tissue damage and wound expansion. The larvae can destroy bones, nasal sinuses, orbital cavities, hard palate, eyeballs, hearing apparatus, and teeth [16, 17].

Oral myiasis has been seen in patients with an open wound, those with epilepsy who sustain trauma to the face, people with poor oral hygiene, individuals who breathe through their mouths, alcoholics, and patients with dementia or hemiplegia [20].

Leukocytosis, neutrophilia, and eosinophilia are common clinical findings in screwworm infections [14, 19].

4.9 Diagnosis

The diagnosis of screwworm infection is based on clinical signs and symptoms [6, 10].

Identification of larvae: The larvae can be identified by their distinct screw-like shape and the presence of rows of spines on the body.

Identification of pupae: The pupae are identified by their barrel-shaped structure and dark colour.

Polymerase chain reaction assay: The PCR assay is a molecular biology technique that detects the presence of specific DNA sequences in a sample. It is an extremely sensitive and specific method that can detect even insignificant amounts of DNA in a sample. The PCR assay has been used to detect C. bezziana DNA in larvae, pupae, and adult flies.

Wing morphometrics: a method of measuring the shape and size of wings. It is used to identify distinct species of flies, including the screwworm. The wing morphometrics of flies can serve as an additional method for screening specimens or providing supporting evidence for a specimen deemed questionable upon direct examination.

Cuticular hydrocarbon profiles: Cuticular hydrocarbons (CHC) are a complex mixture of long-chain alkanes, alkenes, and methyl-branched compounds that are synthesised by epidermal cells and secreted onto the cuticle surface. They play a vital role in insect communication and are used for species recognition, mate choice, and kin recognition. The composition of cuticular hydrocarbons is species-specific and can be used as a diagnostic tool for identifying insects [6, 10]. CHC has been used for species identification for decades and effectively discriminates against insect taxa. CHC analysis has also been used for Diptera, providing a complementary technique when taxonomical identification is ambiguous or not feasible [21].

Identification of adult flies: The thorax of the New World screwworm is metallic dark blue to blue-green, while its head is reddish orange. On the thorax, there are three longitudinal dark stripes running along the back. In contrast, the Old World Screwworm has a metallic blue, bluish-purple, or blue-green appearance, featuring two transverse stripes on its thorax. Adult screwworms are uncommonly seen [9].

Serological tests: There are currently no approved serological tests for diagnosing this illness, nor are they recommended. Experimental studies have demonstrated the potential value of serological approaches in future research on the incidence of screwworm infestations in animal populations to find antibodies to screwworms after an infestation [6, 9].

4.10 Treatment approach

Prompt and effective treatment is necessary to control human screwworm infestations [11]. The primary goals of treatment are the eradication of larvae and the prevention of secondary infections. It is crucial to mechanically remove larvae through surgical debridement, wound irrigation, and the application of larvicidal agents.

Systemic antibiotics, such as amoxicillin with clavulanic acid, metronidazole, and cefazolin, are commonly used to prevent or treat secondary bacterial infections. In selected cases, pharmacological antihelminthic agents such as ivermectin, mebendazole, and albendazole may be considered for systemic treatment [22, 23].

Screwworm infestations require immediate surgical intervention to control the infestation, prevent further tissue damage, and minimise the risk of secondary infections [14].

Debridement: Debridement is a fundamental surgical technique for removing necrotic and infected tissue. In screwworm infestations, aggressive debridement of the affected area is crucial to eliminate the larvae and prevent further migration. In response to light, larvae bury deeper into the tissue to escape the light. This action is called negative phototaxis due to photoreceptors on their anterior end [23].

Surgical instruments, such as forceps and scissors, are used to meticulously remove the larvae, avoiding leaving remnants behind [19, 24, 25]. If larvae are removed forcefully, they may not be removed entirely, resulting in the retention of larval tissue, which may lead to granulomatous inflammation and calcification [23].

Wound Irrigation: Wound irrigation is an essential step following debridement to flush out any remaining larvae or debris. It helps in reducing bacterial load and promoting wound healing. Normal saline or antiseptic solutions can be used for irrigation, ensuring thorough coverage of the wound and its surrounding area. High-pressure irrigation may be required to dislodge and remove attached larvae [19, 24, 25, 26, 27].

Wound Closure: The decision regarding wound closure depends on the extent and depth of tissue damage. Primary closure using sutures or staples may be appropriate in cases where the wound is clean, well-vascularised, and without signs of infection. However, if there is a risk of ongoing infestation, evidence of disease, or extensive tissue loss, delayed closure techniques, such as secondary intention healing or skin grafts or flaps, may be considered [19, 22, 24, 25].

Pressure irrigation is frequently recommended after initial surgical debridement of necrotic and malignant tissue when treating cases of cutaneous wound malignancy. Depending on the size and location of the malignant wound, more complex surgical procedures may be needed for wound closure. The best course of treatment is still complete surgical excision with histologically tumour-free margins [19].

The optimal approach to treating myiasis involves the removal of all visible larvae and, if necessary, removing necrotic tissue through debridement. This treatment process can become complex due to the larvae tunnelling away from the wound. Wound irrigation is often recommended to deal with this reverse burrowing. Another potential topical therapy is a solution containing 1% ivermectin in propylene glycol. In addition to surgical extraction, systemic antihelminth drugs like albendazole or ivermectin (as it has been successfully used in treating our patient) can be used in treating the patients. In some cases where conventional methods were ineffective, vacuum removal using venom extractors has been employed [28].

4.11 Postoperative care

After surgical intervention, meticulous wound care is crucial to prevent complications. Regular dressing changes, wound inspection, and appropriate use of topical antimicrobial agents are recommended. Close monitoring for signs of infection, wound dehiscence, or larval reappearance is necessary to ensure a favourable outcome [29].

4.12 Addressing the psychological impact of the infection

Physical symptoms like bad odour, pain, and discharge can lead to significant psychological issues, often causing feelings of isolation. Isolationism can exacerbate wounds, as illustrated by the occurrence of myiasis in this case. Quality of life is a major consideration in the management of malignant wounds, and it is crucial to address the psychological impact that such wounds can have on patients. This underrepresentation is likely due to the patient’s psychological denial or avoidance of issues related to their oncologic condition [28].

4.13 Ivermectin

Ivermectin is a semisynthetic macrocyclic lactone antibiotic derived from the bacterium Streptomyces avermitilis. It has been shown to be effective against various parasites, including Strongyloides stercoralis, Ancylostoma braziliense, Cochliomyia hominivorax, Dermatobia hominis, Wuchereria malayi, Onchocerca volvulus, and Loa loa. Additionally, ivermectin is effective against ectoparasites such as Sarcoptes scabiei, Pediculus humanus, Demodex folliculorum, and Cheyletiella species. Ivermectin has become an essential alternative for treating patients with different forms of ectoparasite infestations, such as scabies, head lice, demodicosis and myiasis [20, 30].

Ivermectin is usually used in veterinary medicine and is effective in humans for treating filarial, scabies, and strongyloidiasis [31].

Ivermectin enhances the release of gamma-aminobutyric acid (GABA) from the nerve terminals of endoparasites (nematodes) and increases the affinity of GABA for synaptic receptors. This results in the activation of GABA-gated Cl⁻ channels, which increases the Cl⁻ content in cells, causing hyperpolarisation, paralysis, and parasite death. Like endoparasites, the mechanism of action of GABA in arthropods (ectoparasites) involves the interruption of nerve impulses between nerve ends and muscle cells [13].

One case report described a patient with destructive rhino-orbital myiasis caused by larvae of the NWS, who was successfully treated with oral ivermectin prior to surgery. The patient received a single oral dose of ivermectin at 200 mg/kg, and intravenous clindamycin was started to manage the infection. The patient showed continuous improvement, and complete resolution of the myiasis was observed after 48 hours. Orbital exenteration was subsequently performed. No larvae were observed during the surgery or in the pathological examination of the orbital contents [31].

There is evidence indicating that patients with facial trauma and NWS infection were treated with subcutaneous ivermectin therapy, alongside the application of a phenol preparation (10% creolin) as a local measure to control larvae. After an average of 12 days in the hospital, no larvae were found in the patients’ mouths, and they were subsequently discharged. Healing was uneventful in the six cases presented, and no undesirable reactions were observed throughout the period of treatment [1].

In South Africa, ivermectin is not registered for human use. However, the South African health products regulatory authority (SAHPRA) can occasionally grant topical ivermectin in humans for treating skin conditions like head lice or scabies under Section 21 of the Medicines and related substances act. This act provides SAHPRA with the authority to grant the use of unregistered medicine to various applicants throughout the country [32].

4.14 Prevention strategies

Screwworm prevention strategies include the following:

Information Campaign and Continuing Education: Public support is essential. The information campaign is responsible for communicating with the public on how to control NWS to support the eradication effort. This campaign is focused on collecting and reporting myiasis samples, treating wounds, avoiding transport of infested animals, preventing movement, explaining the use of sterile flies and that they are not dangerous, and reporting to the public on progress achieved and specific actions required.

Surveillance: The surveillance system must be capable of detecting new outbreaks of screwworms promptly. This undertaking requires a network of trained personnel identifying the disease and collecting samples for laboratory confirmation.

Treatment: Infected animals must be treated promptly with appropriate insecticides or other methods [6, 8, 33].

Eradication: SIT (sterile insect technique): This involves a weekly aerial release of sexually sterilised laboratory-reared flies over infested areas. Mating between wild females and sterile males produces no offspring, thus interrupting the life cycle and progressively reducing the wild population to the point of elimination, thus reducing the population of screwworms. This method successfully eradicated screwworms from North and Central America [6, 8].

Quarantine: This involves preventing the introduction of animals from areas where screwworms are present to areas where they are not [6].

Movement Controls: This aims to prevent the spread of screwworms from a possible endemic area to a nonendemic area. Animal movements across borderlines must be controlled through inspection and verification.

Chemical control: This involves using insecticides to kill adult flies or larvae. However, this method is not recommended as it can lead to resistance in screwworm populations [6, 8].

Biological control involves using natural predators or parasites to control screwworm populations. For example, the parasitic wasp Spalangia endius has been used successfully to control screwworms in Australia [6].

Research: Research is essential in improving existing methods and developing new ones for controlling screwworms. Technologies like GIS (Geographical Information Systems), GPS (Global Positioning Systems), and screwworm models are being integrated to predict the spread of screwworm populations. These new systems will allow appropriate management decisions based on the diversity of climate and microclimatic conditions in mountains and canyons where the parasite can survive, even in states where the general environment is unfavourable. The models also include wild animal distribution and migratory habits of various species that may function as reservoir populations [8].

International collaboration and cooperation between the Local Governments, the international Food and Agriculture Organisations, and the many other worldwide agencies and donor countries are vital to understanding the effects of screwworms and to plan and effect meaningful change [33].

4.15 Clinical implications

Although malignant wounds are known risk factors for wound myiasis, they have recently begun to be recorded. Myiasis of body parts, particularly in terminally ill cancer patients, may evoke thoughts of the impending decomposition and prostration of the entire body, resulting in long-lasting psychological effects that compromise the patients’ treatment outcome and quality of life. Myiasis is usually associated with squamous and basal cell carcinoma, considered “open skin” cancers. Myiasis is associated with angiosarcoma, eccrine adnexal neoplasia, breast cancer, laryngeal carcinoma, melanoblastoma, Kaposi’s sarcoma, Non-lymphoma, Hodgkin’s, and cervical cancer. The symptoms resemble wound myiasis, and foul-smelling fluids may indicate maggot infestation. In none of the known cases has the infected person suffered permanent health impairment [19].

When possible, the surgical removal of a tumour is considered optimal treatment. But, in certain circumstances, particularly cancers of the head and neck, extensive disease is possible without treatment. For the prevention of myiasis, the care of any wound is paramount. The best therapy for these patients is the removal of larvae from the wound, which may include or exclude wound irrigation. Oral ivermectin treatment is an option when mechanical removal is not recommended [19].

4.16 Limitations

Lack of comparison group: The case report does not include a comparison group or control group for evaluating the efficacy or outcomes of the interventions, making it difficult to determine the specific impact of the treatment options, such as ivermectin, on the patient’s condition.

Limited generalizability: The case report focuses on a single patient with unique characteristics, such as age, medical history, and exposure history. The findings may not apply to all patients with basal cell carcinoma or screwworm infestations.

Subjective nature: Case reports can be influenced by the authors’ observations and interpretations. The information provided may be biased or limited by the individual perspectives and experiences of the authors.

Incomplete follow-up: The report does not provide information about the long-term outcomes or potential complications after the surgical intervention and treatment. Long-term follow-up is essential to assess the complete treatment trajectory and evaluate the overall success of interventions.

These limitations should be considered when interpreting findings from a single case report and recognising the need for further research, such as case series or controlled studies, to provide more robust evidence on the topic.

4.17 Future directions

Future research possibilities in the study of screwworms include [34]:

Further investigation into differences in cuticular hydrocarbons among mass-reared strains and field populations of screwworms.

A high-quality reference genome for blow flies will facilitate further investigations and study efforts, enhancing the making of transgenic sexing strains. Developing genetic sexing strain for Blow flies reduces the costs associated with fly production and release [35].

Expanding the distribution of OWS fly into fresh regions of the Middle East may lead to the development of an AW-IPM (area-wide integrated pest management) program in that region.

Integrating genetic data of the screwworm population with various biological data in a GIS (geographic information system) provides a unique insight that correlates genetic variations with environmental variations and other parameters.

Utilise biomolecule analyses to determine the nutrient needs of screwworms for enhancing their diet and mass rearing.

To continue the exploration of the various genetic differences in screwworms utilising molecular genetic techniques and analyses.

Improve sterile fly release strategies by applying landscape analysis and geographic information systems, allowing an understanding of the landscape genetics of screwworms.