Traumatic myiasis in free-ranging eland, reported from Kenya

Human myiasis in Sub-Saharan Africa: A systematic review

BACKGROUND

Human myiasis is a parasitic dipteran fly infestation that infects humans and vertebrates worldwide. However, the disease is endemic in Sub-Saharan Africa and Latin America. In Sub-Saharan Africa, it is under-reported and therefore its prevalence is unknown. This systematic review aims to elucidate the prevalence of human myiasis, factors that influence the infection, and myiasis-causing fly species in SSA. The review also dwelled on the common myiasis types and treatment methods of human myiasis.

METHODS

Here, we collect cases of human myiasis in Sub-Saharan Africa based on literature retrieved from PubMed, Google Scholar and Science Direct from 1959 to 2022. A total of 75 articles and 157 cases were included in the study. The recommendations of PRISMA 2020 were used for the realization of this systematic review.

RESULTS

In total, 157 cases of human myiasis in SSA were reviewed. Eleven fly species (Cordylobia anthropophaga, Cordylobia rodhaini, Dermatobia hominis, Lucilia cuprina, Lucilia sericata, Oestrus ovis, Sarcophaga spp., Sarcophaga nodosa, Chrysomya megacephala, Chrysomya chloropyga and Clogmia albipuntum) were found to cause human myiasis in SSA. Cordylobia anthropophaga was the most prevalent myiasis-causing species of the reported cases (n = 104, 66.2%). More than half of the reported cases were from travelers returning from SSA (n = 122, 77.7%). Cutaneous myiasis was the most common clinical presentation of the disease (n = 86, 54.7%). Females were more infected (n = 78, 49.6%) than males, and there was a higher infestation in adults than young children.

CONCLUSION

The findings of this study reveals that international travelers to Sub-Saharan Africa were mostly infested therefore, we recommend that both international travelers and natives of SSA be enlightened by public health officers about the disease and its risk factors at entry points in SSA and the community level respectively. Clinicians in Sub-Saharan Africa often misdiagnose the disease and most of them lack the expertise to properly identify larvae, so we recommend the extensive use of molecular identification methods instead.

Pedicle myiasis by Lucilia caesar (Diptera, Calliphoridae): An emerging disease in roe deer from north-western Spain

A total of 35 male roe deer (Capreolus capreolus) from Lugo province (north-western Spain) were examined for pedicle myiasis between 2020 and 2022. All these animals had died by different causes and were examined or preserved just after their death to avoid post-mortem infestations. After external and internal head inspection, five animals were diagnosed with severe myiasis at the basis of the antlers (14.29%; 95% confidence interval = 5.38-31.04). All the affected bucks presented a cutaneous wound (1.5-15 cm in diameter) around the pedicles with extensive tissue destruction, exposition of frontal and parietal bones, and massive infestation by dipteran larvae (2-12 mm long). Four of five roe deer showed whitish egg clusters adhered to the basis of the antlers. Moreover, in one animal, six larvae had penetrated the cranial cavity, and in two of them larvae were also found in the nasopharyngeal cavity. All the cases were recorded in summer (May-August). Morphological identification and subsequent molecular confirmation revealed that all animals were infested by different larval stages of Lucilia caesar (Diptera: Calliphoridae). This study represents the first report of pedicle myiasis in Spain. Since this disease is reported sporadically, the detection of five cases in a short period of time suggests an increase in the incidence of this myiasis.

Prevalence, Etiology, and Risk Factors Associated with Occurrence of Canine Cutaneous Myiasis in Kitui County, Kenya

Myiasis is the infestation of living tissues of animals with dipterous larvae. In Africa, Cordylobia species (C. anthropophaga, C. rodhaini, and C. ruandae) and Dermatobia hominis are reported as the principal cause of nonmigratory cutaneous myiasis of domestic animals. None of these have been reported in dogs in Kenya. A cross-sectional study was conducted in eight subcounties of Kitui County, Kenya, from March to August 2021 to estimate the prevalence, risk factors, and etiological agents associated with canine cutaneous myiasis (CCM). A questionnaire was administered to dog owners to collect information on CCM risk factors. A total of 400 dogs were physically examined and larvae collected from myiasis skin lesions and preserved in 70% ethanol, taken to the laboratory, processed and identified using parasitological morphological features. Live larvae were incubated and emerging adults were captured and identified. The overall prevalence of CCM was 45% (180/400) (95% confidence interval: 40.0–50.0%). A total of 434 larvae were collected from 180 dogs infested with cutaneous myiasis. All larvae (100%) were identified as C. anthropophaga and hatched adults were “tumbu” flies. There were no significant differences in the prevalence of CCM at 95% confidence interval among different age and sex groups ( $p>0.05$ ), although puppies (<6 months) appeared more affected. The highest prevalence of myiasis was in Kitui Central at 65% (95% confidence interval: 51.6–76.9%), Mwingi North at 52.5% (95% confidence interval: 36.1–68.4%), Kitui South at 48.5% (95% confidence interval: 31.5–63.9%), Kitui Rural at 40% (95% confidence interval: 27.6–53.5%), Mwingi Central at 40% (95% confidence interval: 24.9–56.7%), Mwingi West at 40% (95% confidence interval: 24.9–56.7%), Kitui West at 38.3% (95% confidence interval: 26.1–51.8%), and Kitui East subcounty at 36.7% (95% confidence interval: 24.6–50.1%). Lack of housing, housing structures, and dog living area environmental hygiene were the main risk factors associated with the occurrence of CCM ( $p<0.05$ ). The CCM occurrence was significantly different among breeds ( $p<0.05$ ). Cordylobia anthropophaga larvae were the etiological agent of CCM in Kitui County. There is a need for improved dog housing and hygiene measures to prevent the occurrence of CCM, and affected dogs should be treated to prevent the spread of CCM among the dogs.

Wound myiasis in a wild boar by Lucilia caesar (Diptera: Calliphoridae): First case and current status of animal myiasis by this species

The first case of myiasis caused by Lucilia caesar (L.) (Diptera: Calliphoridae) in a wild boar, Sus scrofa L. (Artiodactyla: Suidae) is described. The myiasis occurred in October 2019 in Southern Italy and the identification of the agent was based on adult male morphology. The wild boar had a wound on its right side, near the neck, which was largely infested by larvae. The ecology, distribution and current literature status about cases of animal myiasis by this species is also included.

RETROSPECTIVE EVALUATION OF A NOVEL SUSTAINED-RELEASE IVERMECTIN VARNISH FOR TREATMENT OF WOUND MYIASIS IN ZOO-HOUSED ANIMALS

Myiasis is a major disease condition in human and veterinary medicine. Domestic, free-ranging, and zoo-housed animals can be severely affected by myiasis. Depending on case severity, multiple treatment episodes may be indicated and can lead to recurrent capturing, handling stress, and anesthetics, all of which increase the risk of adverse responses (including death) individually and also in the herd. As an insecticide, ivermectin is often used for larval control. A total of 28 individual myiasis cases were retrospectively evaluated, out of which 11 cases were also treated using an ivermectin sustained-release varnish (SRV). The clinical outcome of all cases was assessed and the results suggest that the use of a topical ivermectin SRV (with or without concurrent injectable ivermectin) can reduce handling and treatments, has no adverse effects, and has minimal recurrence of the disease when compared with cases treated without it.

Traumatic Myiasis: A Neglected Disease in a Changing World

Traumatic myiasis, the parasitic infestation by fly larvae in traumatic lesions of the tissues of living vertebrates, is a serious medical condition in humans and a welfare and economic issue in domestic animals. New molecular studies are providing insights into its evolution and epidemiology. Nevertheless, its incidence in humans is generally underreported, particularly in tropical and subtropical regions. Myiasis in domestic animals has been studied more extensively, but continuous management is difficult and expensive. A key concern is the inadvertent introduction and global spread of agents of myiasis into nonendemic areas, facilitated by climate change and global transport. The incursion of the New World screwworm fly (Cochliomyia hominivorax) into Libya is the most notable of many such range shifts and demonstrates the potential risks of these parasites and the costs of removing them once established in a geographic area. Nevertheless, the insect agents of myiasis can be of societal benefit to forensic science and in medicine as an aid to wound treatment (larval therapy).

Reference gene stability of a synanthropic fly, Chrysomya megacephala

Background

Stable reference genes are essential for accurate normalization in gene expression studies with reverse transcription quantitative polymerase chain reaction (qPCR). A synanthropic fly, Chrysomya megacephala, is a well known medical vector and forensic indicator. Unfortunately, previous studies did not look at the stability of reference genes used in C. megacephala.

Results

In this study, the expression level of Actin, ribosomal protein L8 (Rpl8), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), elongation factor 1α (EF1), α-tubulin (α-TUB), β-tubulin (β-TUB), TATA binding box (TBP), 18S rRNA (18S) and ribosomal protein S7 (Rps7) were evaluated for their stability using online software RefFinder, which combines the normal software of the ΔCt method, BestKeeper, Normfinder, and geNorm. Moreover the number of suitable reference gene pairs was also suggested by Excel-based geNorm. The expression levels of these reference genes were evaluated under different experimental conditions with special perspectives of forensic applications: developmental stages (eggs, first, second and third instar larvae, pupae and adults); food sources of larvae (pork, fish and chicken); feeding larvae with drugs (untreated control, Estazolam and Marvelon); feeding larvae with heavy metals (untreated control, cadmium and zinc); tissues of adults (head, thorax, abdomen, legs and wings). According to RefFinder, EF1 was the most suitable reference gene of developmental stages, food and tissues; 18S and GAPDH were the most suitable reference genes for drugs and heavy metals, respectively, which could be widely used for quantification of target gene expression with qPCR in C. megacephala. Suitable reference gene pairs were also suggested by geNorm.

Conclusion

This fundamental but vital work should facilitate the gene studies of related biological processes and deepen the understanding in physiology, toxicology, and especially medical and forensic entomology of C. megacephala.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1175-9) contains supplementary material, which is available to authorized users.

Traumatic Myiasis Caused by an Association of Sarcophaga tibialis (Diptera: Sarcophagidae) and Lucilia sericata (Diptera: Calliphoridae) in a Domestic Cat in Italy

We describe here a rare case of traumatic myiasis occurred in August 2014, caused by an association of 2 Diptera species, Sarcophaga tibialis Macquart (Diptera: Sarcophagidae) and Lucilia sericata (Meigen) (Diptera: Calliphoridae), in a domestic cat in northern Italy. Species identification was based on adult male morphology. The present case is the first report of S. tibialis as an agent of myiasis in Italy, and also the first ever report of myiasis caused by an association of S. tibialis and L. sericata. The cat developed an extensive traumatic myiasis in a large wound on the rump, which was treated pharmacologically and surgically. The biology, ecology, and distribution of S. tibialis and L. sericata are also discussed. A literature review is provided on cases of myiasis caused by S. tibialis, and cases of myiasis by L. sericata involving cats worldwide and humans and animals in Italy.