Cutaneous Myiasis Caused by Chrysomya megacephala in an Infant with Psoriasis Vulgaris

Age determination of Chrysomya megacephala (Diptera: Calliphoridae) using lifespan patterns, gene expression, and pteridine concentration under constant and variable temperatures

Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae), is a blowfly species widely studied in medical, veterinary, and entomological research. Our study examined the impact of constant (15, 20, 25, 30, and 35 °C) and variable (ranging from 21.0 to 25.4 °C, with an average of 23.31 °C) temperatures on the development and larval body length of C. megacephala. Additionally, we analyzed the age of the adult C. megacephala through pteridine content and related metabolic genes analysis. Our findings revealed three distinct growth patterns: isomorphen diagram, isomegalen diagram, and thermal accumulated models. At constant temperatures of 15, 20, 25, 30, and 35 °C, egg-hatching times were 44.5 ± 8.9, 26.7 ± 4.6, 12.6 ± 1.1, 11.0 ± 1.0, and 9.9 ± 1.9 h, respectively, while it was 15.3 ± 5.9 h at variable temperatures. The total development times from oviposition to adult eclosion in C. megacephala required 858.1 ± 69.2, 362.3 ± 5.9, 289.6 ± 17.8, 207.3 ± 9.3, and 184.7 ± 12.1 h at constant temperatures of 15, 20, 25, 30, and 35 °C, respectively. This duration was extended to 282.0 ± 64.1 h under variable temperatures. However, no significant differences were found in hatching times and the total developmental durations between 25 °C and variable temperatures. A developmental threshold temperature (D0) of 9.90 ± 0.77 °C and a thermal summation constant (K) of 4244.0 ± 347.0° hours were ascertained. Pteridine content patterns varied significantly across constant temperatures, but not between 25 °C and variable temperatures. Sex and temperature were identified as the primary factors influencing pteridine levels in the head of C. megacephala. Gene expression associated with pteridine metabolism decreased following adult eclosion, matching with increased pteridine concentration. Further investigations are needed to explore the use of pteridine cofactors for age-grading adult necrophagous flies. These findings provide valuable insights into the lifespan of C. megacephala, thereby offering valuable groundwork for forthcoming investigations and PMImin determination.

Atrophie blanche complicated with lower limb infection and maggot growth: A case report

Background

Atrophie blanche (AB) is a thrombotic vascular disease, also known as venous vasculitis or segmental hyaline vasculitis, characterized by chronic recurring painful ulcers on the lower legs, especially the ankles. AB is a clinically rare condition, affecting 1%–5% of the population, specifically middle-aged women with an average age of 45 years, and cases of AB in children are rare. Following recovery, ivory-white atrophy spots accompanied by pigmentation and telangiectasia remain in patients. One of the complications of AB is the parasitic growth of microorganisms infecting the ischemic soft tissue undergoing necrosis in the lower limbs. Furthermore, although infection combined with microbial parasitism is a type of surgical site infection, myiasis is particularly rare, which may warrant limb amputation or may even be life-threatening. Understanding the complications of AB may help in early and timely surgical debridement as well as wound repair. Summarizing the knowledge and treatment strategies of AB and formulating clinical strategies and guidelines for AB management with insights from relevant cases are important.

Case summary

A 59-year-old woman was hospitalized due to repeated ulceration of the skin of the right lower leg for 3 years, aggravation, and maggot growth for 3 days. In the previous 3 years, the skin and soft tissue of the right calf had become ischemic, necrotic, and infected, but the patient did not seek any medical treatment. Subsequently, 2 years ago, she was diagnosed with AB at the dermatology department of our hospital. After hormone treatment, her right leg improved. However, 1 year ago, the skin and soft tissue of the right leg again became ischemic, necrotic, and infected. This time, the patient did not seek medical treatment and applied musk on her wound. The wound deepened, resulting in the exposure of the tendon and some bones. In addition, a large number of maggots and microorganisms grew in and infested the wound for 3 days before the patient came to our department for treatment. Debridement of the necrotizing infected site on the right lower leg combined with negative pressure vacuum sealing drainage were performed twice within 16 days after admission. Simultaneously, antibiotics were given systemically. On the 17th day after admission, the wound appeared clean, myiasis had resolved, and the growth and coverage of the granulation tissue on the wound were satisfactory. Subsequently, debridement of the infected site on the right leg, removal of skin of the right thigh, and autologous free skin grafting were performed. After 10 days, the wound was clean, all skin grafts had survived, and wound repair was satisfactory. Finally, the patient was discharged after 38 days of hospitalization.

Conclusion

Although AB is rare, leukodystrophy requires specialized treatment and regular follow-up. If lower limb infection and maggot growth occur simultaneously, self-treatment should be avoided and medical attention must be sought immediately. Early implementation of wound debridement and anti-infective treatment combined with wound repair, which should be performed after cleaning the wound, is advised.