Human Dirofilariasis Caused by Dirofilaria repens in Sri Lanka from 1962 to 2020

Dirofilariasis Causing Pediatric Acute Scrotum: A Case Series and Review of the Literature

Introduction

Dirofilarial infestation has been reported as an extremely rare cause of pediatric acute scrotum. We aimed to evaluate clinical, radiological, and intraoperative findings of children who underwent surgical management for acute scrotum due to dirofilariasis in an endemic country.

Materials and Methods

A retrospective study of patient records of children who underwent surgery for acute scrotum due to dirofilariasis between 2018 and 2022.

Results

There were eight emergency presentations for acute scrotum due to dirofilariasis. Three presentations (37.5%) were not associated with scrotal pain. The median age at presentation was 59 (range: 19-100) months. Four patients (67.7%) underwent emergency scrotal exploration at the first presentation and another one during the second presentation. Recurrent episodes were seen in two patients who were initially managed nonsurgically with antibiotics alone. Ultrasonography was performed in all six patients and revealed a parasitic nodule in three (50%).

Conclusions

Dirofilariasis causing acute scrotum may cause significant diagnostic dilemma for clinicians. It may resemble idiopathic scrotal edema since it predominantly affects boys under 6 years of age and is painless in a significant proportion. However, left unoperated, it appears to have a high recurrence rate.

Zoonotic dirofilariases: one, no one, or more than one parasite

Dirofilaria spp. are vector-borne filarial nematodes that affect a variety of animal species, including humans. Dirofilaria immitis and Dirofilaria repens are the two main zoonotic species, but also other wildlife-associated Dirofilaria species are occasionally reported as causative agents of human dirofilariasis, including Dirofilaria striata, Dirofilaria tenuis, Dirofilaria ursi, Dirofilaria spectans, and Dirofilaria magnilarvata. Since the etiological identity of most of the species mentioned here is arguable, we summarized and critically discussed data concerning infections in humans, focusing on the reliability of Dirofilaria species identification. We advocate the importance of combined morphological and genomic approaches to provide unequivocal evidence for their zoonotic potential and pathogenicity.

The prevalence of canine dirofilariasis in China: a systematic review and meta-analysis

BACKGROUND

Dirofilariasis, the disease caused by Dirofilaria spp., and in particular by Dirofilaria immitis and Dirofilaria repens in canines, occurs frequently in canids and felids, and occasionally in humans, in temperate, sub-tropical and tropical regions globally. Although highly effective, safe and convenient preventive medicines have been available for the treatment of dirofilariasis for the past three decades, the disease remains a major veterinary and public health concern in endemic areas. The insect vectors, host-parasite relationships and interactions of Dirofilaria spp. have received little attention in China, and there is very little information in English regarding the prevalence of dirofilariasis in animals and humans in the country. The aim of this systematic review and meta-analysis is to evaluate the status of canine dirofilariasis in China based on the available literature in English and in Chinese.

METHODS

We systematically searched five databases for epidemiologic studies on the prevalence of canine dirofilariasis in China and finally selected 42 studies eligible for inclusion in the systematic review and meta-analysis. The meta-analysis was performed using the random effects model in the meta package in R v4.2.1.

RESULTS

The random effects model gave a pooled and weighted prevalence of Dirofilaria infection among dogs in China in the past 100 years of 13.8% (2896/51,313, 95% confidence interval 8.2-20.4%) with a high level of heterogeneity (I² =  99.5%).

CONCLUSIONS

Our analyses indicated that the prevalence of canine dirofilariasis in China has gradually declined, but that the range of Dirofilaria spp. has expanded. Older and outdoor dogs presented a higher rate of positive infection. The findings indicated that more attention should be paid to host factors for the effective control and management of this disease.

Dirofilarial nodule as a differential diagnosis for subcutaneous lumps in children

PURPOSE

Subcutaneous nodules in children are commonly caused by pilomatrixoma, dermoid cysts, soft tissue tumors, etc. Parasitic infections are reported to cause subcutaneous nodules and are infrequently described, mostly in the adult literature. We aim to describe the clinicopathological features of subcutaneous lumps caused by dirofilarial infestation in children in an endemic country.

METHODS

A retrospective analysis was performed of all patients presenting with the above condition to Lady Ridgeway Hospital from 2018 to 2022 and their relevant details were captured in a proforma.

RESULTS

There were 55 patients with a male to female ratio of 2:1. The mean age at presentation was 50 months (7-156 months). The mean duration was 97 days (1-820 days). The common sites involved were scrotum (30.9%), back (14.5%), abdominal wall (102.7%) and face (10.9%). The majority had a painless nodule (70.9%), while ten (18.2%) had features of acute inflammation. Thirty (55.5%) had preoperative ultrasonography which showed features of parasitic nodules in 26 (47.3%). Parasite was demonstrated in histopathological analysis only in 30 patients (54.5%).

CONCLUSION

Dirofilarial nodule should be considered in the differential diagnosis of subcutaneous lumps in children, especially in the endemic areas.