Observations of the third instar larva and puparium of Chrysomya bezziana (Diptera: Calliphoridae)

Severe Orbital Myiasis Caused by Chrysomya bezziana: A Case Report

An 88-year-old woman was brought to the hospital immediately after her neighbours noticed that she was bleeding from her right eye. On examination, her right eye was phthisic with maggot infestation of her right orbit. Over a hundred live maggots were extracted using forceps. Computed tomography scan revealed the infestation was confined to the right orbit. The patient underwent exenteration of the right orbit under general anaesthesia. The species was identified by an entomologist as Chrysomya bezziana, which has aggressive larvae that eat living tissue. This case report demonstrates that orbital myiasis caused by C. bezziana poses a very real risk of intracranial invasion as they feed on living tissues. Adjacent tissue destruction can be very rapid and definitive treatment involves urgent removal of its larvae via surgical debridement. To our knowledge, we are reporting the first case of orbital myiasis from a patient in Malaysia. Therefore, our case report may be helpful in the management of similar case of orbital myiasis.

Human Chrysomya bezziana myiasis: A systematic review

Background

Myiasis due to Old World screw-worm fly, Chrysomya bezziana, is an important obligate zoonotic disease in the OIE-list of diseases and is found throughout much of Africa, the Indian subcontinent, southeast and east Asia. C. bezziana myiasis causes not only morbidity and death to animals and humans, but also economic losses in the livestock industries. Because of the aggressive and destructive nature of this disease in hosts, we initiated this study to provide a comprehensive understanding of human myiasis caused by C. bezziana.

Methods

We searched the databases in English (PubMed, Embase and African Index Medicus) and Chinese (CNKI, Wanfang, and Duxiu), and international government online reports to 6^th February, 2019, to identify studies concerning C. bezziana. Another ten human cases in China and Papua New Guinea that our team had recorded were also included.

Results

We retrieved 1,048 reports from which 202 studies were ultimately eligible for inclusion in the present descriptive analyses. Since the first human case due to C. bezziana was reported in 1909, we have summarized 291 cases and found that these cases often occurred in patients with poor hygiene, low socio-economic conditions, old age, and underlying diseases including infections, age-related diseases, and noninfectious chronic diseases. But C. bezziana myiasis appears largely neglected as a serious medical or veterinary condition, with human and animal cases only reported in 16 and 24 countries respectively, despite this fly species being recorded in 44 countries worldwide.

Conclusion

Our findings indicate that cryptic myiasis cases due to the obligate parasite, C. bezziana, are under-recognized. Through this study on C. bezziana etiology, clinical features, diagnosis, treatment, epidemiology, prevention and control, we call for more vigilance and awareness of the disease from governments, health authorities, clinicians, veterinary workers, nursing homes, and also the general public.

Chrysomya bezziana larvae are characterized by feeding aggressively on the living tissues and body fluids of the host. The dreadful feelings of patients suffering from myiases with severe tissue and bone destruction, even death, and the enormous economic losses in the livestock industries have been described previously. But our findings indicate that C. bezziana myiases still appear to be under-recognized as a serious medical or veterinary condition throughout the world. Both in China and the world at large, it is probable that C. bezziana distribution could well be greater than currently reported. Our study provides an opportunity for clinicians and health authorities to gain a comprehensive understanding of this disease from its etiology, clinical features, diagnosis, treatment, epidemiology, prevention and control. In addition, our findings will engage governments, health staff, veterinary workers, aged-care facilities, and also the general public, in efforts to recognize, prevent, and control such infestations.

Connecting the Dots: From an Easy Method to Computerized Species Determination

Differences in growth rate of forensically important dipteran larvae make species determination an essential requisite for an accurate estimation of time since colonization of the body. Interspecific morphological similarities, however, complicate species determination. Muscle attachment site (MAS) patterns on the inside of the cuticula of fly larvae are species specific and grow proportionally with the animal. The patterns can therefore be used for species identification, as well as age estimation in forensically important dipteran larvae. Additionally, in species where determination has proven to be difficult—even when employing genetic methods—this easy and cheap method can be successfully applied. The method was validated for a number of Calliphoridae, as well as Sarcophagidae; for Piophilidae species, however, the method proved to be inapt. The aim of this article is to assess the utility of the MAS method for applications in forensic entomology. Furthermore, the authors are currently engineering automation for pattern acquisition in order to expand the scope of the method. Automation is also required for the fast and reasonable application of MAS for species determination. Using filters on digital microscope pictures and cross-correlating them within their frequency range allows for a calculation of the correlation coefficients. Such pattern recognition permits an automatic comparison of one larva with a database of MAS reference patterns in order to find the correct, or at least the most likely, species. This facilitates species determination in immature stages of forensically important flies and economizes time investment, as rearing to adult flies will no longer be required.

Scanning Electron Microscopy Investigations of Third-Instar Larva of Cordylobia rodhaini (Diptera: Calliphoridae), an Agent of Furuncular Myiasis

A scanning electron microscopy study of the third larval instar of Cordylobia rodhaini Gedoelst (Diptera: Calliphoridae), causing obligatory furuncular myiasis, is presented here for the first time. The larvae were collected from a patient exposed to them in the tropical rainforest of Kibale National Park (Uganda). Distinctive features are described in sequence from the anterior region to the posterior region, highlighting the morphological features of antennae, maxillary palps, structures related to mouth opening, sensory structures, thoracic and abdominal spines, and anterior and posterior spiracles. The results are compared with those of other Calyptrata flies, mainly from the family Calliphoridae and, when possible, with Cordylobia anthropophaga Blanchard (Diptera: Calliphoridae), the only other species of genus Cordylobia investigated by scanning electron microscopy.

Occurrence of Chrysomya bezziana in a buffalo in Jammu

Cutaneous myiasis caused by the Old World screw-worm fly, Chrysomya bezziana, is a commonly occurring infestation of livestock and man in Southeast Asian and African countries. A buffalo, aged five years was presented with traumatic wound in the abnormal growth at the base of tail, housing maggots in it. Based on morphological features, the collected larvae were identified as C. bezziana larvae. The first ever occurrence of C. bezziana in a buffalo from this part of country and its public health significance have been discussed.

Marked for life: muscle attachment site patterns in blowfly larvae are constant throughout development

The muscular attachment sites (MAS) of blowfly larvae can be visualised as "dots" by removing and staining the cuticle. Each segment bears several rows of MAS. The silhouettes of a subset of those rows in the second, third, and fourth segments were previously shown to be specific for four species of L3 blowfly larvae. In this investigation, the MAS patterns are described for a fifth species (Protophormia terraenovae) and throughout larval development of Calliphora vicina and Calliphora vomitoria. The patterns of P. terraenovae show considerable differences to those of the Calliphora species (larger MAS, characteristic "M" shape in row 4A), thus providing further evidence for the viability of the method as tool for species determination. Larvae with a body length of only 3 mm already show a complete set of MAS expressing identical pattern characteristics as L3 larvae with maximal body length. These characteristics are largely unchanged throughout development. Plotting the row length as a function of the body length throughout development reveals a linear correlation. Therefore, in case of requirement (e.g. fragmentation), not only the species but also the approximate larval age can be calculated with this method.

Observations on morphology of immature Lucilia porphyrina (Diptera: Calliphoridae), a fly species of forensic importance

Lucilia porphyrina (Walker) is a blow fly of forensic importance, and shares its geographical distribution with a related forensically important species, Lucilia cuprina (Wiedemann). The immature stages of both species are similar in general appearance; therefore, correct identification should be given special consideration. This study highlighted the main features of L. porphyrina larvae, as observed under light microscopy and scanning electron microscopy. Particular attention is given to the anterior and posterior spiracles, cephalopharyngeal skeleton, and characteristics of the dorsal spines between the prothorax and mesothorax. In the third instar specifically, morphological information on L. porphyrina showed several features that are shared by L. cuprina, and therefore need certain identification to distinguish between them. Such key features are (1) greater posterior spiracle, (2) apparent inner projection between the middle and lower slits of the posterior spiracle, and (3) strongly sclerotized peritreme. The number of papillae on the anterior spiracle may be a supplement, five to nine and three to six in L. porphyrina and L. cuprina, respectively. The key for identifying third instar of forensically important flies in Thailand has been updated to include L. porphyrina.