Prevalence of the endosymbiont Wolbachia in heartworms (Dirofilaria immitis)

Detection of Wolbachia in Dirofilaria infected dogs in Portugal

Wolbachia pipiens, an intracellular endosymbiont bacteria of filarial nematodes, has been implicated in the pathogenesis of filarial diseases, in particular in heavy Dirofilaria spp. infections. Antibiotic therapy (doxycycline) against Wolbachia has been proven to be suitable adjunct therapy, prior to adulticide treatment of canine dirofilariosis. Despite its importance, investigation on the Wolbachia/Dirofilaria complex in Portugal had not been undertaken so far. This study reports the first detection of Wolbachia in Dirofilaria spp. infected dogs in the context of an ongoing epidemiological survey in central-south regions in the country. Wolbachia DNA was detected by PCR in 52.6% (20/38) of canine blood samples positive for Dirofilaria immitis based on parasitological (Knott's and Acid Phosphatase) and serological (Witness(®)Dirofilaria) methods. No Wolbachia DNA could be detected in samples from dogs with occult infections (parasite negative but antigen positive). The lack of Wolbachia detection in some microfilaremic dogs was somewhat unexpected and needs to be elucidated in further studies, as the presence or absence of these bacteria in association with microfilaria is of importance for veterinarians in the management and control of canine dirofilariosis.

Wolbachia, filariae and Leishmania coinfection in dogs from a Mediterranean area

OBJECTIVES

In an endemic area for leishmaniosis and filariasis, coinfection can occur and the immunomodulation triggered by Wolbachia infection might influence the clinical signs and progression of both diseases. The aims of this study were to determine the prevalence of Wolbachia in dogs infected with Dirofilaria immitis and other filarial nematodes, to evaluate the prevalence of coinfection of Leishmania infantum, filariae and Wolbachia and their association with clinical presentation.

METHODS

Polymerase chain reaction assays were performed to detect filarial species, Wolbachia species and Leishmania in 118 samples of dogs from southeastern Spain with leishmaniosis and/or filariasis.

RESULTS

Ninety-eight dogs were infected with Leishmania and 49 had filarial infection (29 were coinfected with both). Wolbachia DNA was detected in 30·6% of filariae-positive dogs (15/49). Dogs coinfected with Leishmania and filaria had more severe clinical signs. Wolbachia infection was significantly (P=0·026) more frequent in dogs that were not infected with Leishmania. There was no correlation between outcome and coinfection with these pathogens.

CLINICAL SIGNIFICANCE

This study highlights the increased sensitivity of polymerase chain reaction in the diagnosis of filariasis, confirms the presence of Wolbachia in dogs from the Mediterranean basin, shows the increased severity of clinical signs when Leishmania-filarial coinfection is present and suggests a protective role of Wolbachia in leishmaniosis.

Detection of Wolbachia DNA in blood for diagnosing filaria-associated syndromes in cats

A fundamental role for the endosymbiotic bacteria Wolbachia pipientis in the pathogenesis of Dirofilaria immitis infections has emerged in recent years. Diagnostic opportunities arising from this breakthrough have not yet been fully exploited. This study was aimed at developing conventional and real-time PCR assays to carry out a molecular survey in a convenience sample of cats living in an area where D. immitis is endemic and to evaluate the detection of bacterial DNA in blood as a surrogate assay for diagnosing filaria-associated syndromes in cats. COI and FtsZ loci were used as targets for D. immitis and Wolbachia PCR assays, respectively, and real-time TaqMan PCR assays were used only for Wolbachia. A convenience sample of 307 disease-affected or healthy cats examined at a University facility were PCR tested, and their medical records were investigated. Conventional nested PCR for Wolbachia amplified the endosymbionts of both D. immitis and D. repens, while real-time PCR was highly specific only for the former. Observed prevalences of 0.3 and 10.4% were found using conventional nested PCR assays for D. immitis and real-time PCR for Wolbachia, respectively. Similar prevalences were established using the Wolbachia nested PCR (98% concordance with real-time PCR). The group of Wolbachia-positive samples had a significantly higher proportion of subjects with respiratory signs (29.0% versus 9.7%; P = 0.002). The findings of this study indicate that a highly sensitive PCR assay can be used to detect the Wolbachia organism in the peripheral blood of cats with respiratory signs.