The synanthropic moth fly Clogmia albipunctata is commonly found in humid human-associated environments and has been reported in suspected human myiasis cases, including intestinal presentations. Larvae are frequently recovered from fecal samples, but direct experimental evidence that eggs or larvae can withstand gastrointestinal conditions and establish true intestinal colonization has been lacking. This study combined standardized in vitro digestion models and an in vivo murine oral gavage model to evaluate whether C. albipunctata eggs or early-instar larvae can survive, hatch, develop, or colonize the digestive tract under simulated human digestive conditions and in a mammalian host.
Field-caught C. albipunctata were collected from humid sites near Bengbu Medical University and used to establish a stable laboratory colony. The breeding system used semi-natural conditions with aquarium filter pads as oviposition and pupation substrates. Species identity of the laboratory colony was confirmed by morphological characterization and by molecular analysis using COI barcoding. The article reports successful colonization in the laboratory and confirmation of species identity; specific morphological and molecular details are provided in the source publication.
An in vitro simulated gastrointestinal digestion model, based on standardized INFOGEST protocols, was applied to assess egg hatchability and larval survival. Eggs and larvae were exposed to simulated gastric fluids and sequenced through simulated intestinal conditions to mimic human digestive processes. The experiments tested standard simulated gastric fluid as well as weaker postprandial acidic conditions (pH 2.0–5.0) followed by intestinal fluid exposure. Survival and development outcomes were monitored after these treatments. The source provides quantitative outcomes for hatchability and larval mortality under these conditions.
To complement the in vitro data, female BALB/c mice (7 weeks old, 18–22 g) were used for oral gavage experiments. Mice were housed under specific-pathogen-free conditions and acclimatized before experiments; animal welfare procedures and humane endpoints were described and followed according to institutional approval. Viable eggs and live first-instar larvae were administered by gavage. Feces were examined daily for seven consecutive days, and necropsies with histological examination of gastrointestinal tissues were performed at prespecified time points to assess for shedding, tissue injury, or evidence of colonization.
The study successfully reared C. albipunctata in laboratory conditions and confirmed species identity through morphology and COI barcoding. This provided a reproducible source of eggs and larvae for the experimental investigations described below.
The in vitro digestion experiments showed that standard simulated gastric fluid acted as a strong lethal barrier for both eggs and larvae. Reported outcomes include a decline in egg hatchability from 76.80% ± 3.57% in controls to 0% after exposure to simulated gastric digestion. Larval mortality increased from 19.17% ± 3.01% in controls to 99.17% ± 0.83% following simulated gastric exposure. Simulated postprandial weaker acidic conditions (pH 2.0–5.0) partially attenuated lethality, but sequential exposure to simulated intestinal fluid induced additional mortality. These results indicate that human-like digestive fluids and gastric acidity substantially reduce viability of C. albipunctata eggs and larvae in vitro.
In the murine oral gavage experiments, administration of viable eggs and live first-instar larvae produced no fecal shedding of larvae, no observable tissue injury, and no pathological colonization of the gastrointestinal tract by C. albipunctata. Mice were monitored for clinical signs and sampled by time-point necropsy with histological assessment; the study reports no evidence supporting survival or establishment of the ingested stages under the conditions tested.
Combining in vitro and in vivo data, the authors conclude that healthy gastrointestinal conditions—modeled both by simulated human digestive fluids and by the intact murine gut—are highly unfavorable for survival and colonization of C. albipunctata eggs and larvae. The findings support the interpretation that many reported clinical detections of C. albipunctata in fecal samples likely reflect sample contamination, accidental passage (pseudomyiasis), or environmental exposure rather than true intestinal myiasis with intraluminal development.
The results reinforce the need for cautious interpretation of larvae found in feces. Where possible, investigators and clinicians should consider contamination and pseudomyiasis in differential assessment before diagnosing true intestinal myiasis and initiating antiparasitic treatment. The study emphasizes the value of controlled experimental data to inform clinical judgment about the pathogenic potential of synanthropic insects encountered in human samples.
The article reports ethical approval, animal housing and monitoring conditions, and funding sources. The source states that all relevant data are within the paper and supporting information files. Specific experimental parameters and additional methodological details are provided in the original publication; if further granular details are required, readers should consult the full article and its supporting information.