What are the alternatives to chloroform for the treatment of maggots?

Comment by InpharmD Researcher

Management of myiasis (maggot/larval infestation) has traditionally relied upon mechanical removal, including physical and surgical extraction and irrigation/debridement supplemented with chloroform or ether/turpentine oil. However, much of the literature supporting first-line and alternative strategies for myiasis is based on case reviews/series and veterinary data, and there is limited robust clinical trial data. Alternatives to chloroform include standard wound-cleansing solutions (e.g., Dakin’s, povidone/iodine, isopropyl alcohol, and hydrogen peroxide) and topical or oral ivermectin. Ivermectin has shown effectiveness across multiple contexts, including as monotherapy and in combination/triple therapy with albendazole and clindamycin. Ivermectin has additionally shown superior maggot clearance rates vs chloroform, suggesting a possible role for earlier initiation of ivermectin-based regimens; however, this remains to be supported by large, prospective clinical studies in humans.
Background

A 2012 narrative review comprehensively examines myiasis, including its evaluation and management strategies. Myiasis is defined as the infestation of live vertebrates (humans and/or animals) with dipterous larvae from flies. Anatomical classification of myiasis includes sanguinivorous (bloodsucking), dermal-subdermal (cutaneous tissue-destroying), nasopharyngeal (infestation of the head passages), intestinal, and urogenital. First-line management centers on mechanical removal of larvae. Recommended strategies for mechanical removal include: (1) occlusion of the respiratory punctum via application of petrolatum, liquid paraffin, or similar substances to induce hypoxia and force larval emergence, after which the larvae can be physically removed using forceps; (2) surgical excision of deeply embedded/anchored larvae; and (3) irrigation and debridement of wound-based myiasis supplemented by chloroform oil, ether, or turpentine to immobilize the larvae. Alternatives to mechanical removal include pharmacologic treatment with anti-helminthic agents (using 1% topical or oral ivermectin dosed at 150-200 mcg/kg, predominantly reserved for malignant wounds or otherwise inaccessible larvae). Species-specific alternative strategies and adjunctive antibiotics for secondary infectious prophylaxis can also be considered. The author notes that much of the literature in this area is derived from case reports and also extrapolation from veterinary data, and that robust, randomized clinical trial data in humans is largely lacking. [1]

Background References: [1] Francesconi F, Lupi O. Myiasis. Clin Microbiol Rev. 2012;25(1):79-105. doi:10.1128/CMR.00010-11
Literature Review

A search of the published medical literature revealed 4 studies investigating the researchable question:

What are the alternatives to chloroform for the treatment of maggots?

Level of evidence

C - Multiple studies with limitations or conflicting results  Read more→


Please see Tables 1-4 for your response.

Effectiveness of wound cleansing treatments on maggot (Diptera, Calliphoridae) mortality
Design

Experimental study

N= 25 (5 replicates for each of the 5 treatments)
Objective To determine the effectiveness of common wound cleansers on maggot mortality
Study Groups

Dakin’s solution (n= 5)

Isopropyl alcohol (n= 5)

Betadine (n= 5)

Hydrogen peroxide (n= 5)

Control, as deionized water (n= 5)
Inclusion Criteria Lucilia sericata (Diptera: Calliphoridae) larvae from a reared population at Michigan State University
Exclusion Criteria None specified
Methods Five treatments were applied: 0.50% sodium hypochlorite (Dakin’s solution), 70% isopropyl alcohol, 10% povodine–iodine (Betadine), 3% hydrogen peroxide, and deionized water as control. Each treatment was applied to groups of 50 larvae in jars with beef liver as food starting after 24 hours upon assignmnet to individual jars. Treatments were sprayed daily for 14 days, and mortality was assessed every 24 hours.
Duration 14 days
Outcome Measures

Primary: Total mean mortality of maggots at 14 days

Secondary: Differences in mortality among treatments over time
Baseline Characteristics   All treatments (N= 25)
Initial larvae per jar 50
Temperature 18°C
Light-dark cycle 3:21 h
Results   Mean Total Mortality (%)
Dakin’s solution 46
Isopropyl alcohol 42
Betadine 37
Hydrogen peroxide 33
Control 25
Adverse Events None reported
Study Author Conclusions Traditional wound cleansing solutions may not be sufficient for maggot infestations of pre-existing wounds, and supplemental treatments may be necessary to effectively treat cases of wound myiasis.
Critique The study provides valuable insights into the effectiveness of common wound cleansing solutions on maggot mortality, but it is limited by the small sample size and lack of significant differences among treatments. The study's findings suggest that none of the tested solutions were completely effective, indicating a need for additional or alternative treatments for wound myiasis.
Table 1 References:
[2] McIntosh MD, Merritt RW, Kolar RE, Kimbirauskas RK. Effectiveness of wound cleansing treatments on maggot (Diptera, Calliphoridae) mortality. Forensic Sci Int. 2011;210(1-3):12-15. doi:10.1016/j.forsciint.2011.01.028

Management of Malignant Wound Myiasis with Ivermectin, Albendazole, and Clindamycin (Triple Therapy) in Advanced Head-and-Neck Cancer Patients: A Prospective Observational Study
Design

Single-center, prospective observational study

N= 25
Objective To study the effectiveness of systemic ivermectin, albendazole, and clindamycin (Triple Therapy) in reducing signs and symptoms associated with maggots in malignant head and neck wounds
Study Groups All patients (N= 25)
Inclusion Criteria Adult, advanced head and neck cancer patients with maggots from wound, oral cavity, or nostril; Eastern Cooperative Oncology Group (ECOG) score 3 or less; able to take at least liquids with or without nasogastric tube (NGT)
Exclusion Criteria Not explicitly stated
Methods Patients received oral ivermectin 12 mg per day for 3 days, albendazole 400 mg twice per day for 3 days, and clindamycin 300 mg three times per day for 5 days. Wounds were treated with turpentine oil dressing and maggots were manually removed. Oral morphine 10 mg immediate release was administered as needed for pain management.
Duration 7 days
Outcome Measures

Primary: Reduction in number of maggots

Secondary: Improvement in wound-related symptoms and overall symptom profile
Baseline Characteristics  

All patients

(N= 25)
Age (years), mean±SD 42.15±8.23
Weight (kg), mean±SD 52.31±5.18
Sex ratio (male:female) 21:4
Patients with NGT 8
Patients with tracheostomy 4
Maggots in wound only 16
Maggots from wound and nasal cavity 2
Maggots from wound and oral cavity 7
Daily oral morphine requirement (mg), mean±SD 100.38±42.38
Results   Day 0 Day 1 Day 3 Day 5 Day 7
Pain on dressing 8.36±1.036 7.56±0.651* 5.16±0.746* 3.48±0.510* 1.96±0.841*
Pain in between dressing 8.36±1.036 7.04±0.611* 4.36±0.490* 3.40±0.500* 2.36±0.490*
Odor 9.56±0.507 7.16±0.624* 4.28±0.458* 1.72±0.980* 0.76±0.779*
Exudation 9.04±0.790 8.52±0.510* 7.48±0.510* 4.76±0.723* 2.76±1.234*
Itching 8.60±1.000 8.28±0.614* 6.00±0.707* 3.60±1.190* 3.16±0.987*
Bleeding 3.76±2.107 4.32±2.212** 3.12±1.536* 2.44±1.083* 1.72±1.275*
Edema 8.80±0.913 8.52±0.510** 7.20±0.500* 5.24±0.723* 3.64±0.995*
Distress score on distress thermometer (DT) 9.60±0.500 8.88±0.666* 7.24±0.723* 5.96±0.676* 3.92±0.759*
Number of maggots 77.28±13.465 20.60±7.263* 1.52±2.104* Not present Not present
*p< 0.05; **p> 0.05.
Adverse Events Diarrhea in 7 patients (28%), headache in 10 patients (40%), giddiness in 5 patients (20%).
Study Author Conclusions Systemic treatment with ivermectin, albendazole, and clindamycin (Triple Therapy) enhances the removal of maggots, early recovery, and relief from distress and associated symptoms.
Critique The study provides evidence for the effectiveness of triple therapy in treating myiasis in cancer patients, with significant symptom improvement. However, the small sample size and single-center design may limit the generalizability of the findings. Additionally, the lack of a control group makes it difficult to attribute improvements solely to the treatment regimen vs other potential confounders that were not accounted for in the study design/methodology.
Table 2 References:
[3] Patel BC, Ostwal S, Sanghavi PR, Joshi G, Singh R. Management of Malignant Wound Myiasis with Ivermectin, Albendazole, and Clindamycin (Triple Therapy) in Advanced Head-and-Neck Cancer Patients: A Prospective Observational Study. Indian J Palliat Care. 2018 Oct-Dec;24(4):459-464. doi:10.4103/IJPC.IJPC_112_18

Ivermectin: A Novel Method of Treatment of Nasal and Nasopharyngeal Myiasis
Design

Prospective, single-center study in India

N= 80
Objective To evaluate the efficacy of oral ivermectin in patients suffering from nasal and nasopharyngeal myiasis
Study Groups

Group I: Manual extraction with chloroform and turpentine oil (n= 40)

Group II: Manual extraction with oral ivermectin (n= 40)
Inclusion Criteria All patients with nasal and nasopharyngeal myiasis
Exclusion Criteria Children <5 years old; active pregnancy
Methods Patients were randomly divided into two groups. Group I underwent manual extraction of maggots after instillation of chloroform and turpentine oil mixture. Group II underwent manual extraction with administration of two doses (24 h apart) of oral ivermectin (6 mg per dose). Endoscopic evaluation was performed at 24, 48 hours, and 7 days after initial examination. All patients were given oral analgesics, antibiotics and systemic decongestants. They were advised alkaline nasal douching, to maintain good personal hygiene and to sleep in mosquito nets.
Duration August 2015 to November 2017
Outcome Measures

Primary: Mean maggot shedding time

Secondary: Endoscopic clearance of maggots at 24 and 48 hours
Baseline Characteristics  

Group I

(n= 40)

Group II

(n= 40)
Male 18 (45%) 16 (40%)
Mean age, years 54.3
Rural background 74 (92.5%)
Diabetes mellitus 53 (66.25%)
Atrophic rhinitis 39 (48.75%)
Maggots in nose 69 (86.25%)
Results  

Group I

(n= 40)

Group II

(n= 40)

 p-value
Mean maggot shedding time, hours 41.2±4.26 24.6±3.15 0.0001
Complete clearance at 24 h 18 (45%) 32 (80%) 0.002
Complete clearance at 48 h 28 (70%) 38 (95%) 0.006
Adverse Events No systemic or local side effects reported with oral ivermectin.
Study Author Conclusions Oral ivermectin is an effective and better alternative to conventional treatments for nasal and nasopharyngeal myiasis, offering early maggot clearance, reduced morbidity, and shorter hospital stays.
Critique The study's prospective design and randomization are strengths, providing robust data on the efficacy of oral Ivermectin. However, the study is limited by its relatively small sample size and lack of long-term follow-up to assess recurrence rates. Additionally, the study was conducted in a single center, which may limit the generalizability of the findings to other settings.
Table 3 References:
[4] Sayeed A, Ahmed A, Sharma SC, Hasan SA. Ivermectin: A Novel Method of Treatment of Nasal and Nasopharyngeal Myiasis. Indian J Otolaryngol Head Neck Surg. 2019;71(Suppl 3):2019-2024. doi:10.1007/s12070-018-1444-y

 

Combination ivermectin therapy to treat nasal myiasis: A case series

Design

Case series

(N= 5)

Case presentation

 This case series described five consecutive patients with nasal myiasis treated at a single U.S. institution between 2020 and 2021. All cases occurred during summer months in sedated or comatose, intubated patients (average age 46.4 years, 60% male), with 60% having a nasogastric tube in place; average time from hospitalization to myiasis onset was 4.2 days, supporting a nosocomial source of infestation. Each patient underwent nasal cavity debridement combined with systemic ivermectin (12 mg orally daily) and topical ivermectin suspension irrigations (6 mg twice daily) for seven days. All five patients were completely cleared of larvae by day seven, with no adverse events attributed to treatment; one patient was later declared brain-dead from an unrelated subdural hematoma.

Study Author Conclusions

This serves as the only known case series of nasal myiasis in western literature and provides a treatment regimen that has been both safe and effective in practice thus far.

The findings emphasize that despite advanced hospital care standards, opportunistic infestations such as nasal myiasis can occur in vulnerable, critically ill patients, necessitating prompt recognition and a structured management protocol to prevent morbidity.
Table 4 References:
[5] Davies C, Naylor T, Rangarajan S, Yawn R. Combination ivermectin therapy to treat nasal myiasis: A case series. Otolaryngology Case Reports. 2023;27:100535. doi:10.1016/j.xocr.2023.100535