Introduction
Furuncular myiasis is caused by taxonomically and geographically diverse dipteran flies whose larvae infest the skin of vertebrate hosts (Baird et al. Reference Baird, Baird and Sabrosky1989; Solomon et al. Reference Solomon, Lachish and Schwartz2016; Mathison et al. Reference Mathison, Cramner, Cox, Jerris and Couturier2022). As larvae develop, they create painful boils (‘furuncles’) that can ooze serosanguineous fluid, which also contains larval faeces and can become secondarily infected with bacteria (Günther, Reference Günther1971; Geary et al. Reference Geary, Russell, Hudson and Hardy1999). Furuncular myiasis is usually mild and self-limiting (if unpleasant), but it can be severe in some cases (Pampiglione et al. Reference Pampiglione, Schiavon and Fioravanti1992; Wade et al. Reference Wade, Shahi, Mawer and Brown2019; Muñoz et al. Reference Muñoz, Galvis, Patiño and Moneriz2021; Jesuyajolu and Jesuyajolu, Reference Jesuyajolu and Jesuyajolu2022). In the tropics, the most commonly reported taxa are the human botfly Dermatobia hominis Linnaeus Jr. 1781 (Oestridae) in South and Central America (Villalobos et al. Reference Villalobos, Vega-Memije, Maravilla and Martinez-Hernandez2016; Ragi et al. Reference Ragi, Kapila and Schwartz2021) and blowflies of the genus Cordylobia Grünberg 1903 (Calliphoridae) in Africa (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024).
Furuncular myiasis in Africa has been described in the medical literature since the 1800s (Zumpt, Reference Zumpt1965). In the early 1900s, scientists in endemic countries made detailed morphological descriptions of the flies, surveyed domestic animals and wildlife to identify reservoirs, and conducted experimental infestations (Zumpt, Reference Zumpt1965). Since then, most publications have been case reports involving travellers returning from Sub-Saharan Africa (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). Such patients typically present with symptoms initially misdiagnosed as insect bites, pyoderma, inflamed epidermoid cysts or similar conditions, and patients often receive antibiotics before the actual cause is identified (Grassi et al. Reference Grassi, Butterworth and Latiffi2016; Solomon et al. Reference Solomon, Lachish and Schwartz2016; Muñoz et al. Reference Muñoz, Galvis, Patiño and Moneriz2021; Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). The number of cases of furuncular myiasis exported from Africa is almost certainly higher than the number reported in the literature (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). Case reports may be biased towards ‘dramatic’ infestations involving, for example, extraordinary intensities (in some cases over 100 larvae) or disquieting anatomic locations (Brodin and Rodhain, Reference Brodin and Rodhain1910; Pampiglione et al. Reference Pampiglione, Schiavon and Fioravanti1992; Grassi et al. Reference Grassi, Butterworth and Latiffi2016; Wade et al. Reference Wade, Shahi, Mawer and Brown2019; Jesuyajolu and Jesuyajolu, Reference Jesuyajolu and Jesuyajolu2022). Studies of the ecology of these flies have been all but absent since initial investigations in the early 1900s, which shaped prevailing paradigms about their natural history (Zumpt, Reference Zumpt1965).
Here, I describe a study of fly larvae causing furuncular myiasis in Kibale National Park, Uganda (‘Kibale’, hereafter). Kibale is a tropical forest in the biodiverse Albertine Rift of East Africa, and its diversity and density of non-human primates (‘primates’ hereafter) is exceptional (Oates et al. Reference Oates, Whitesides, Davies, Waterman, Green, Dasilva and Mole1990; Plumptre et al. Reference Plumptre, Davenport, Behangana, Kityo, Eilu, Ssegawa, Ewango, Meirte, Kahindo, Herremans, Peterhans, Pilgrimg, Wilson, Languy and Moyer2007). Kibale is also a ‘hotspot’ for furuncular myiasis, as evidenced by the high risk of contracting the condition for visitors to the park (personal observation) and by its representation in case reports involving international travellers returning with the condition (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). Among the community of research personnel at Kibale and among residents of communities adjacent to the park, ‘ebimonde’ (singular ‘ekimonde’) or ‘mango flies’ (the local colloquial terms for the causative larvae in Rutooro and English, respectively) are a well-known and common nuisance. However, to my knowledge, no formal studies of these flies have previously been performed in Kibale.
Using field observations and fly larvae collected over a decade from people and primates in Kibale, this study sheds new light on the ecology of a lesser-known cause of furuncular myiasis, Lund’s fly (Cordylobia rodhaini Gedœlst 1909). Female flies of this species and other members of the genus Cordylobia lay eggs on soil contaminated with urine or faeces, on fruit, or on wet surfaces. The eggs hatch, and first instar larvae undergo questing behaviour in response to movement or warmth (Günther, Reference Günther1971). After attaching to a host, larvae burrow into the skin, where they develop to the third instar stage over approximately 1 to 2 weeks (Rodhain and Bequaert, Reference Rodhain and Bequaert1916; Geary et al. Reference Geary, Russell, Hudson and Hardy1999). Mature larvae excyst, fall to the ground, burrow approximately 4–8 cm into the soil, pupate and emerge as adults approximately 25 days later (Rodhain and Bequaert, Reference Rodhain and Bequaert1916; Günther, Reference Günther1971; Geary et al. Reference Geary, Russell, Hudson and Hardy1999). Relevant to human infestation, females have a vexing predilection for ovipositing on wet clothing hung to dry (Zumpt, Reference Zumpt1965; Pampiglione et al. Reference Pampiglione, Schiavon and Fioravanti1992; Hall and Smith, Reference Hall, Smith, Lane and Crosskey1993). Data presented herein suggest that aspects of this lifecycle may have evolved in response to specialization on primates. In general, host preference may be a decisive factor in the evolutionary divergence of species within the genus Cordylobia, providing an informative example of how myiasis-causing flies can adapt to different ecological settings and be regionally rare but locally abundant.
Materials and methods
Field studies
Larvae were collected from primates that had been anesthetized and released back to their social groups as part of separate studies of health and conservation (Goldberg et al. Reference Goldberg, Paige, Chapman, Aguirre, Daszak and Ostfeld2012; Paige et al. Reference Paige, Malave, Mbabazi, Mayer and Goldberg2015); details of animal capture and sampling have been described previously (Lauck et al. Reference Lauck, Hyeroba, Tumukunde, Weny, Lank, Chapman, O’Connor, Friedrich and Goldberg2011). When a furuncle was found during physical examination, steady digital pressure was applied to its base until the larva was expelled. Larvae were immediately placed in RNAlater nucleic acid stabilization solution (Thermo Fisher, Waltham, MA, USA) to facilitate future studies of both DNA and RNA and were stored at −20°C. Only 1 larva per primate infestation was used for molecular analysis, to avoid pseudoreplication (i.e. analysing multiple larvae from the same oviposition event).
Larvae from humans (Homo sapiens Linnaeus 1758) were obtained through unsolicited donations from individuals who had heard of this author’s peculiar interest in these parasites. When larvae were received, they were immediately placed in RNAlater and stored as above. As with primates, only 1 larva per human infestation was used for molecular analysis.
Laboratory studies
Larvae were photographed using methods previously described for other parasitic fly larvae (Friant et al. Reference Friant, Young and Goldberg2022). Briefly, a JVC KY-F75U digital camera attached to a Leica Z16 APO dissecting microscope with apochromatic zoom objective and motor focus drive was used to capture images of larvae from each host species sampled. Larvae were illuminated by a LED ring light and dual gooseneck fibre optic illuminators. A Syncroscopy Auto-Montage system (Synoptics, Cambridge, UK) and associated software was then used to create image stacks from white-balance-corrected individual images. Photoshop v. 25.4.0 (Adobe, San Jose, CA, USA) was used to crop stacked (montaged) images and to normalize exposure and colour balance. Larvae were identified morphologically using a dichotomous key (Zumpt, Reference Zumpt1965).
DNA was extracted from larvae using the DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany) according to the manufacturer’s protocol. DNA barcoding was performed by amplifying and sequencing a 657 base pair region of the cytochrome oxidase subunit 1 (cox1) gene, as previously described (Ramírez-Martínez et al. Reference Ramírez-Martínez, Bennett, Dunn, Yuill and Goldberg2021). Resulting cox1 sequences were aligned with MUSCLE (Edgar, Reference Edgar2004) to homologous calliphorid cox1 sequences in GenBank as of October 6 2025. Where more than 1 published sequence was available for a species, the 2 maximally divergent sequences (measured as percent nucleotide difference) were included to capture the range of known intraspecific variation. A phylogenetic tree was inferred using the maximum likelihood method implemented in PhyML 3.3 (Guindon et al. Reference Guindon, Dufayard, Lefort, Anisimova, Hordijk and Gascuel2010) with smart model selection (Lefort et al. Reference Lefort, Longueville and Gascuel2017) and 1000 bootstrap replicates to assess statistical support for clades.
Results
Field studies
From 2010 to 2014, larvae were collected from 11 primates of out of 114 primates sampled, for a period prevalence of 9·6% (95% confidence interval 5·3%–16·6%). The 11 infested primates included 9 red colobus monkeys (Piliocolobus tephrosceles Elliot 1907), 1 red-tailed guenon (Cercopithecus ascanius Audebert 1799) and 1 black-and-white colobus monkey (Colobus guereza Rüppell 1835). These 11 primates had between 1 and 9 larvae, with an average of 1·9 larvae per infestation (standard error of the mean = 1·7), although this is likely an underestimate due to the difficulty of finding lesions on parts of the body covered with hair. All larvae collected were removed from separate furuncles and appeared morphologically identical. Several primates had empty/healing furuncles, indicating prior infestations and natural emergence of mature third instar larvae. Primates not sampled but observed as part of other research projects also showed visual evidence of furuncular myiasis on hairless regions of the body (face, hands, feet and anogenital region), including olive baboons (Papio anubis Lesson 1827), grey-cheeked mangabeys (Lophocebus albigena J. E. Gray 1850) and eastern chimpanzees (P. t. schweinfurthii Giglioli 1872). Remarkably, eastern chimpanzees were photographed removing larvae from each other’s furuncles during mutual grooming sessions (Figure 1C and D).
Figure 1. Myiasis-causing fly larvae in humans and chimpanzees, Kibale National Park, Uganda. (A) Furuncle on the arm of a human; note oozing fluid. (B) Larva in the process of being expressed from human furuncle using manual pressure. (C) Chimpanzee with large furuncle on left cheek. (D) Chimpanzee removing larva from furuncle on the arm of grooming partner. Photo credits: Jessica Rothman (A and B); Nicholas Brazeau/Kibale Chimpanzee Project (C and D).
From 2011 to 2020, 10 larvae were collected and analysed from humans (including 1 from the left axillary region of this author). Donors were all adults and were an approximately equal mix of local and international research personnel. Donors did not generally specify the anatomic locations of their infestations, although accounts suggested that arms, armpits, torso, legs, face, neck, head and genitals are all possible. Within those anatomic locations, infestations tended to occur in places where clothing comes into firm contact with skin (e.g. the elastic straps of undergarments). All larvae were expressed manually from furuncles when they were still relatively small (Figure 1A and B). Unlike primates, humans had no evidence of past infestations that had matured, nor did anyone report successful attempts to allow larvae to mature (although some tried, in the pursuit of knowledge).
Laboratory studies
Larvae had morphological characteristics consistent with third instar members of the genus Cordylobia, including large, backwardly directed curved spines densely arranged along the exterior (Figure 2A–D) and 2 prominent pseudo cephalic lobes (Figure 2E; Hall and Smith, Reference Hall, Smith, Lane and Crosskey1993; Zumpt, Reference Zumpt1965). All larvae were identified as C. rodhaini based on the presence of tortuous slits of the posterior peritremes (Figure 2F), which is a morphological feature that distinguishes C. rodhaini from Cordylobia ruandae Fain 1953 and the tumbu fly, C. anthropophaga Blanchard & Bérenger-Feraud 1872 (Gedœlst, Reference Gedœlst1910; Zumpt, Reference Zumpt1965). Larvae from primates were 4·5 times larger than larvae from humans (16·2 ± 2·3 mm vs. 3·6 ± 1·1 mm, respectively), consistent with size variation documented in third instar larvae of this genus (Zumpt, Reference Zumpt1965), and this difference was statistically significant (Student’s t = 15·69, 19 degrees of freedom; P < 0·001).
Figure 2. Montaged images of Cordylobia rodhaini third instar larvae from Kibale National Park, Uganda. (A) Larva in toto from this author (a human), ventral aspect. (B) Larva in toto from a black-and-white colobus monkey, ventral aspect. (C) Larva in toto from a red colobus monkey, ventral aspect. (D) Larva in toto from a red-tailed guenon, ventral aspect. (E) Anterior aspect showing pseudo cephalic lobes (PL) and mouth hooks (MH) and (F) posterior aspect showing tortuous slits of the posterior peritremes (TS) and respiratory buttons (RB), of larva from a red colobus monkey.
Sequencing of cox1 was successful for all larvae. Sequences represented 4 haplotypes (sequences differing by at least 1 nucleotide). Haplotype 1 (GenBank PV185638–PV185654) was present in larvae from 8 humans, 7 red colobus monkeys, 1 red-tailed guenon and 1 black-and-white colobus monkey. Haplotype 2 (GenBank PV185655) was present in a larva from a human. Haplotype 3 (GenBank PV185656–PV185657) was present in larvae from 1 human and 1 red colobus monkey. Haplotype 4 (GenBank PV185658) was present in a larva from a red colobus monkey. A phylogenetic tree (Figure 3) shows these haplotypes to form a clade with a sequence of C. rodhaini from a morphologically confirmed third instar larva recovered from a traveller returning to Poland from Uganda in 2018 (Biernat et al. Reference Biernat, Gładysz, Kuna, Sulima, Bykowska-Tumasz and Sontag2025). Haplotype 3 is, in fact, identical to this sequence. Haplotypes 1, 2 and 4 differ from the Polish sequence by 0·523%, 0·697% and 1·22%, respectively. All haplotypes differ from an unidentified Cordylobia sp. from Côte d’Ivoire (GenBank OQ024673) by 1·92% to 2·61%. The clade containing the 4 haplotypes from this study and the unidentified Cordylobia sp. from Côte d’Ivoire is sister to the clade representing C. anthropophaga. Sequences representing the genus Cordylobia cluster separately from those of other myiasis-causing calliphorids (Figure 3). The maximum nucleotide sequence difference within C. rodhaini collected in Kibale (1·52%) falls within the range of maximum nucleotide sequence differences calculated for other species in the analysis (from 0·35% for Lucilia cuprina Wiedemann 1830 to 2·96% for C. anthropophaga; Figure 3).
Figure 3. Maximum likelihood phylogenetic tree of flies in the family Calliphoridae. The tree is based on a 574-position trimmed nucleotide sequence alignment of the mitochondrial cytochrome oxidase subunit 1 gene containing 111 variable positions and a GTR + I model of molecular evolution. Sequences were chosen to represent the maximum degree of variation within each species. Taxon names are followed (in parentheses) by country of origin and GenBank accession number. For the clade representing the genus Cordylobia, silhouettes indicate the host(s) from which specimens were obtained. The 4 haplotypes identified in this study (H1-H4) are highlighted in bold. The tree is midpoint rooted. Numbers beside branches indicate bootstrap values (percent) based on 1000 replicates; only values ≥ 50% are shown. The scale bar indicates nucleotide substitutions per site.
Discussion
Gedœlst first described C. rodhaini in 1905 based on a third instar larva collected in August 1902 from the arm of a ‘commandant Lund’ (Gedœlst, Reference Gedœlst1905). Gedœlst made detailed morphological descriptions but was unable to assign the larva to species, instead coining the provisional designation ‘larve de Lund’ (Gedœlst, Reference Gedœlst1905); thus, ‘Lund’s fly’. Gedœlst further described the species in 1909 from specimens of first, second and third instar larvae and pupae provided by Rodhain and Bequaert in Léopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo; Gedœlst, Reference Gedœlst1910; Rodhain and Bequaert, Reference Rodhain and Bequaert1916). Surcouf (Reference Surcouf1914) and Rodhain and Bequaert (Reference Rodhain and Bequaert1916) provided morphological descriptions of female and male adult specimens, respectively, placing the species in a separate genus, Stasisia, which was subsequently synonymized with the genus Cordylobia (Zumpt, Reference Zumpt1965). Brodin and Rodhain (Reference Brodin and Rodhain1910) first described furuncular myiasis caused by C. rodhaini.
Rodhain and Bequaert conducted the only prior investigation of the lifecycle and natural history of C. rodhaini (Rodhain and Bequaert, Reference Rodhain and Bequaert1916; Zumpt, Reference Zumpt1965), to this author’s knowledge. They documented that adults are crepuscular, remaining mostly immobile from 8 am to 5 pm (Rodhain, Reference Rodhain1915). They successfully established a breeding colony and conducted experimental infestations of guinea pigs (Cavia porcellus Linnaeus 1758), which proved to be suboptimal hosts (Rodhain and Bequaert, Reference Rodhain and Bequaert1916). Similarly, they achieved only limited success with self-infestation experiments (Rodhain and Bequaert, Reference Rodhain and Bequaert1916). However, they observed normal maturation of 5 of 7 larvae in 12–15 days in a naturally infested African pouched rat (Cricetomys gambianus Waterhouse 1840; Rodhain and Bequaert, Reference Rodhain and Bequaert1916). They also reported local knowledge of high infestation rates in C. gambianus and various duikers (forest antelopes of the genus Cephalophus Smith, 1827; Rodhain and Bequaert, Reference Rodhain and Bequaert1916). These observations account for the still-pervasive view that pouched rats and duikers are important reservoir hosts. Later, Zumpt (Reference Zumpt1965) listed various shrews, duikers, squirrels, rats, a gerbil and the mona monkey (Cercopithecus mona Schreber 1774) as hosts of second and/or third instar larvae, but the source of this information is unclear. Although this list of hosts has appeared repeatedly in the subsequent literature, the identity of the true natural reservoir(s) of C. rodhaini should be considered an open question.
Currently, C. rodhaini, is considered an uncommon cause of furuncular myiasis in people, given that it accounts for only 10% of reports of human African cutaneous myiases in the literature, versus 66% of reports attributable to C. anthropophaga (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). Therefore, it was surprising that all 21 larvae analysed from people and primates in Kibale were identified as C. rodhaini. This result was also surprising because the local English term for the parasite, ‘mango fly’, refers to C. anthropophaga, also known as the ‘tumbu fly’ (Blacklock and Thompson, Reference Blacklock and Thompson1923). Inquisitive visitors to Kibale have long assumed C. anthropophaga to be the cause of their unpleasant experiences, based primarily on published reports and internet searching, which reveal this species to be the most common regionally. The origin of the term ‘mango fly’ is unclear, but it may refer to the attraction of C. anthropophaga to fruit (Zumpt, Reference Zumpt1965), such as would be found underneath mango trees (Mangifera indica Linnaeus 1753). Despite the rarity of mango trees within the forests of Kibale, C. rodhaini is abundant there. Rodhain and Bequaert (Reference Rodhain and Bequaert1916) successfully attracted C. rodhaini adults using various fruit juices, making it likely that C. rodhaini forages on the variety of wild fruits that Kibale wildlife (including primates, duiker and African pouched rats) consume, as well as excretions of these animals beneath fruiting trees.
Of case reports of C. rodhaini infestations in the literature as of October 6 2025, 3 of 13 involved visitors to Uganda, with other reports spanning Sub-Saharan Africa, from Ethiopia to Cameroon (Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). Of these 3 reports, 2 identify Kibale as the location where the infestation was acquired (Pezzi et al. Reference Pezzi, Cultrera, Chicca and Leis2015; Wade et al. Reference Wade, Shahi, Mawer and Brown2019), and the 3rd report does not specify a location within Uganda (Veraldi et al. Reference Veraldi, Serini and Suss2014). Uganda has 10 national parks, 5 of which feature tropical forests (Plumptre et al. Reference Plumptre, Ayebare, Behangana, Forrest, Hatanga, Kabuye, Kirunda, Kityo, Mugabe, Namaganda, Nampindo, Nangendo, Nkuutu, Pomeroy, Tushabe and Prinsloo2019; Gessa et al. Reference Gessa, Tayeebwa, Tumwesigye and Rothman2024), but individuals who frequent Uganda’s other forested parks rarely report furuncular myiasis. A confluence of host availability, spatial overlap between people and primates and favourable environmental conditions may account for why Kibale appears to be a ‘hotspot’ for C. rodhaini and furuncular myiasis. Of note, humans are dead-end hosts for C. rodhaini and C. anthropophaga, in that people do not generally tolerate larval maturation (Zumpt, Reference Zumpt1965 and personal observation, although anecdotal reports suggest that a few past visitors to Kibale have succeeded in hosting larvae until spontaneous emergence). Chimpanzees, our closest living relatives, apparently share this intolerance (as they do many other traits), as evidenced by their behaviour of removing larvae from each other’s furuncles (Figure 1D). In addition to ironing one’s clothes thoroughly, measures to control human infestation might include alternatives to open pit latrines and open rubbish pits. The predilection of C. rodhaini for faeces, urine and fruit might attract adult flies to these peridomestic features, thus increasing human infestation risk.
Primates appear to play a more important role in the lifecycle of C. rodhaini than previously suspected. Kibale is known for its diversity and density of primates (Oates et al. Reference Oates, Whitesides, Davies, Waterman, Green, Dasilva and Mole1990; Plumptre et al. Reference Plumptre, Davenport, Behangana, Kityo, Eilu, Ssegawa, Ewango, Meirte, Kahindo, Herremans, Peterhans, Pilgrimg, Wilson, Languy and Moyer2007). Larvae were recovered from 9·6% of primates sampled, and furuncular lesions were observed in other primates. Primates also had empty furuncles, indicating successful maturation of third instar larvae (Rodhain and Bequaert, Reference Rodhain and Bequaert1916). Human and primate activity spaces overlap in Kibale, creating ample opportunities for transmission (Paige et al. Reference Paige, Bleecker, Mayer and Goldberg2017). Pouched rats and duiker do occur in Kibale (Kingdon et al. Reference Kingdon, Happold, Butynski, Hoffman, Happold and Kalina2013a, Reference Kingdon, Happold, Butynski, Hoffman, Happold and Kalinab), so these species may also contribute to the local abundance of C. rodhaini, but Kibale is not known for a high density and biomass of these species, as it is for primates (Oates et al. Reference Oates, Whitesides, Davies, Waterman, Green, Dasilva and Mole1990; Plumptre et al. Reference Plumptre, Davenport, Behangana, Kityo, Eilu, Ssegawa, Ewango, Meirte, Kahindo, Herremans, Peterhans, Pilgrimg, Wilson, Languy and Moyer2007). Specialization of myiasis-causing flies on primates is not without precedent, as evidenced by Cuterebra baeri (Shannon and Greene, Reference Shannon and Greene1926), which preferentially infests primates in the Neotropics and occasionally humans (Shannon and Greene, Reference Shannon and Greene1926; Rondón et al. Reference Rondón, Cavallero, Link, De Meo, González and D’Amelio2023).
C. rodhaini differs from C. anthropophaga in ways that suggest ecological niche differentiation. C. anthropophaga typically infests domestic dogs (Canis familiaris Linnaeus 1758) and other domestic species, having a lifecycle adapted to human peridomestic spaces (Günther, Reference Günther1971; Jallow et al. Reference Jallow, Gassara, Bajinka, Luo, Liu, Cai, Huang and Meng2024). By contrast, C. rodhaini infests wild forest animals but is not known to infest dogs or other domestic animals, having a sylvatic lifecycle (Zumpt, Reference Zumpt1965). As mentioned above, both species have a predilection for ovipositing on wet clothing hung to dry (Zumpt, Reference Zumpt1965; Pampiglione et al. Reference Pampiglione, Schiavon and Fioravanti1992; Hall and Smith, Reference Hall, Smith, Lane and Crosskey1993). This behaviour would seem an inefficient way to infest giant rats, duiker or other hosts implicated as C. rodhaini reservoirs. However, it might reflect a misdirected strategy to deposit eggs on the (often wet) vertical trunks and leaves of trees, such as occur in tropical forests like Kibale, and with which primates come into extensive contact.
A total of 4 haplotypes were found in larvae from humans and primates in Kibale, 1 of which was identical to a previously published sequence from a morphologically confirmed C. rodhaini larva (Biernat et al. Reference Biernat, Gładysz, Kuna, Sulima, Bykowska-Tumasz and Sontag2025). Of these four haplotypes, 2 (H1 and H3) were shared between primates and humans, and the other 2 were closely related. These data suggest that some human infestations likely originate from larvae maturing in primates, in which case furuncular myiasis caused by C. rodhaini can be considered a primate zoonosis. The 4 haplotypes identified in this study were sampled from a single geographically defined population. Nevertheless, these haplotypes were as genetically variable as those from other calliphorid species. Additional characterization of C. rodhaini across its entire range would probably reveal even greater genetic variation. These results support the suspicion of Biernat et al. (Reference Biernat, Gładysz, Kuna, Sulima, Bykowska-Tumasz and Sontag2025) that intraspecific genetic variation in C. rodhaini exists, but they do not resolve whether the divergent sequence from Côte d’Ivoire lies within or outside the degree of variation demarcating the species (Figure 3). The Côte d’Ivoire sequence could represent a geographically and genetically divergent population of C. rodhaini, or it could represent another related taxon.
Studies of the ecology of myiasis-causing flies are difficult because they require a sustained field presence, facilities for rearing and experimentation and extensive sampling of putative hosts in biodiverse ecosystems. In this light, it is important to note that the current study was opportunistic, and sampling was not systematic. Nevertheless, the results point to a significant role of primates in the maintenance of C. rodhaini. More generally, this study sheds light on how parasitic flies can adapt to specific ecological conditions and be regionally rare but locally abundant. It remains unclear what health and fitness effects, if any, C. rodhaini has on wild primates. A study of C. baeri infestation in mantled howler monkeys (Alouatta palliata Gray 1849) in Panama showed that increasing parasite burden was associated with decreased serum albumin levels and increased mortality, with the overall effect of limiting population growth (Milton, Reference Milton1996). Given the painful nature of the clinical condition, the risk of secondary bacterial infection, and the intensities of infestation that can sometimes occur, it is reasonable to posit that the negative effects of C. rodhaini on African primates may be consequential.
Data availability statement
All cox1 sequences were deposited in the NIH National Center for Biotechnology Information GenBank database, accession numbers PV185638–PV185658.
Acknowledgements
Many thanks to the individuals who had the foresight (and fortitude) to donate their larvae in the furtherance of science. I am grateful to David Hyeroba, Geoffrey Weny, Colin Chapman and the staff of the Kibale EcoHealth Project and the Kibale Fish and Monkey Project for assisting with field sampling. Many thanks to John Rusoke for providing Rutooro translations, Dan Young and the University of Wisconsin-Madison Department of Entomology for use of their Auto-Montage system, and Jessica Rothman and Nicholas Brazeau/Kibale Chimpanzee Project for granting permission to use photographs. The Uganda Wildlife Authority and the Uganda National Council for Science and Technology kindly granted permission to conduct this research.
Author contributions
TLG conceived and designed the study. TLG conducted field sampling. TLG performed laboratory work and statistical analyses. TLG wrote the article. TLG read, edited and approved the manuscript.
Financial support
This research was partly supported by the University of Wisconsin-Madison John D. MacArthur Chair Research Professorship (to TLG) and through the use of reagents that would otherwise have expired.
Competing interests
The author declares there are no conflicts of interest.
Ethical standards
Field sampling of non-human primates was approved by the Uganda Wildlife Authority, the Uganda National Council for Science and Technology, and the Institutional Animal Care and Use Committee (IACUC) of the University of Wisconsin-Madison (protocol number V005039). All procedures complied with the American Society of Primatologists Ethical Principles for the Treatment of Non‐Human Primates.
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