Seroprevalence and Current Infections of Canine Vector-Borne Diseases in Costa Rica.

Domestic dogs may carry several vector-borne pathogens, including zoonotic agents, especially in tropical regions like Central America. The epidemiology of these pathogens is prone to change due to urbanization, trade and travel as well as climate change, necessitating repeated monitoring. This study aims to present a comprehensive picture of canine vector-borne diseases in Costa Rica, combining data on seroprevalence with molecular species identification of the causative pathogens. In this survey, 294 dogs from all seven provinces of Costa Rica were included. After a clinical examination, diagnostic blood samples were analyzed with regard to packed cell volume (PCV) and presence of microfilaria. Serum samples were tested for antibodies against Ehrlichia spp., Anaplasma spp., Babesia spp., Borrelia burgdorferi sensu lato (s.l.) as well as antigen of Dirofilaria immitis. Seropositive and microfilaremic blood samples were analyzed by PCR to detect current infections and identify the pathogen species. Overall, 45.24% (133/294, 95% CI: 39.45-51.11%) of dogs were seropositive for at least one of the tested pathogens. Seroprevalence was highest for Ehrlichia spp. (39.46%, 116/294, 95% CI: 33.83-45.29%), followed by Babesia spp. (23.13%, 68/294, 95% CI: 18.43-28.38%), Anaplasma spp. (13.27%, 39/294, 95% CI: 9.61-17.69%), and B. burgdorferi s.l. (0.34%, 1/294, 95% CI: 0.01-1.88%). Generalized linear mixed models indicated a significant association of Ehrlichia-, Anaplasma- and Babesia-seropositivity, as well as a significant effect of age and breed on Ehrlichia-seropositivity. Furthermore, a statistically significant negative effect of Ehrlichia-, Anaplasma-, and Babesia-seropositivity on PCV was found. Regarding current infections, Ehrlichia canis DNA was detected in 51.72% (60/116, 95% CI: 42.26-61.10%) of Ehrlichia-seropositive dogs, while Ehrlichia ewingii and Ehrlichia chaffeensis were not detected. Furthermore, 10.26% (4/39, 95% CI: 2.87-24.22%) of Anaplasma-seropositive dogs were coinfected with Anaplasma phagocytophilum and Anaplasma platys, while one animal (2.56%, 95% CI: 0.65-13.48%) was infected with A. phagocytophilum only. Among Babesia-seropositive dogs, Babesia vogeli and Hepatozoon canis were detected in one animal each (1.47%, 1/68, 95% CI: 0.04-7.92%). Dirofilaria immitis antigen was detected in 4.42% (13/294, 95% CI: 2.38-7.44%) of dogs. In microfilaremic animals, D. immitis as well as Acanthocheilonema reconditum infections were identified. This survey demonstrates that canine vector-borne pathogens, including zoonotic agents like A. phagocytophilum and D. immitis, are widespread in Costa Rica. Thus, protection of dogs from disease-transmitting vectors is recommended from an animal welfare as well as public health perspective.

Seroprevalence and current infections of canine vector-borne diseases in Nicaragua.

BACKGROUND: Vector-borne diseases constitute a major problem for veterinary and public health, especially in tropical regions like Central America. Domestic dogs may be infected with several vector-borne pathogens of zoonotic relevance, which may also severely compromise canine health. METHODS: To assess the prevalence of canine vector-borne diseases in Nicaragua, 329 dogs from seven cities, which were presented to the veterinarian for various reasons, were included in this study. Dogs were examined clinically and diagnostic blood samples were taken for analysis of packed cell volume (PCV) and presence of microfilariae as well as antigen of Dirofilaria immitis and antibodies to Ehrlichia spp., Anaplasma spp. and Borrelia burgdorferi (sensu lato) by use of a commercially available rapid ELISA. To detect current infections, specific PCRs for the detection of E. canis, A. platys and A. phagocytophilum were carried out on blood samples of the respective seropositive dogs. Microfilaremic blood samples, as well as D. immitis antigen positive samples were further subjected to PCR and subsequent sequencing for filarial species identification. RESULTS: Antibodies against Ehrlichia spp. were present in 62.9% of dogs, while Anaplasma spp. seroprevalence was 28.6%. Antibodies against species of both genera were detected in 24.9% of dogs. Borrelia burgdorferi (s.l.) antibodies were not detected. Dirofilaria immitis antigen was present in six animals (1.8%), two of which also showed D. immitis microfilariae in buffy coat. In addition to D. immitis, Acanthocheilonema reconditum was identified by PCR and sequencing in two of four additional microfilaremic blood samples, which were tested negative for D. immitis antigen. Current E. canis infections as defined by DNA detection were present in 58.5% of Ehrlichia-seropositive dogs, while 5.3% of Anaplasma-seropositive dogs were PCR-positive for A. platys, 2.2% for A. phagocytophilum and 16.0% for both Anaplasma species. Current E. canis infection had a statistically significant negative impact on PCV, whereas no relationship between infection status and clinical signs of disease could be observed. CONCLUSIONS: These results indicate that canine vector-borne diseases are widespread in Nicaragua and that dogs may constitute a reservoir for human infection with E. canis, A. phagocytophilum and D. immitis. Thus, the use of repellents or acaricides to protect dogs from vector-borne diseases is strongly recommended.

Detection of Rickettsia monacensis and Rickettsia amblyommatis in ticks collected from dogs in Costa Rica and Nicaragua.

The neotropical climate of Central America provides ideal conditions for ticks, which may transmit several human pathogens, including spotted-fever group Rickettsia. Dogs may act as sentinels or reservoirs for human tick-borne diseases due to shared tick species. Here, ticks were collected from 680 client-owned dogs in Nicaragua and Costa Rica, and a total of 316 tick pools were investigated for Rickettsia infection by quantitative real-time PCR (qPCR) targeting the gltA gene. Subsequently, up to six further genomic targets (16S rDNA, gltA, sca4, ompA, ompB and the 23S-5S intergenic spacer) were investigated for Rickettsia species determination. The predominant tick species was Rhipicephalus sanguineus sensu lato (s.l.) (19.9% of dogs infested in Costa Rica, 48.0% in Nicaragua), followed by Ixodes boliviensis (3.1% in Costa Rica / none in Nicaragua) and Amblyomma ovale (4.8% in Costa Rica, 0.9% in Nicaragua). In total, 22 of 316 tick pools containing 60 of 1023 individual ticks were Rickettsia-positive as determined by qPCR, resulting in a minimum infection rate (MIR) of 2.2%. In detail, MIR in Rh. sanguineus s.l. was 0.7% (7/281 pools), in I. boliviensis 33.3% (12/13 pools) and in A. ovale 9.7% (3/22 pools). For 11 of 12 positive I. boliviensis pools and one of six positive Rh. sanguineus s.l. pools, the species could be determined as R. monacensis. R. amblyommatis was identified in one Rh. sanguineus s.l. pool from Costa Rica and one A. ovale pool from Nicaragua. Nine of 12 R. monacensis-positive tick pools were collected in San Rafael de Heredia, Costa Rica, indicating a high local occurrence in this area. This study supports recent evidence that R. monacensis is present on the American continent. Its high local occurrence among dog-associated I. boliviensis, which may also parasitize humans, in Costa Rica gives cause for concern, as R. monacensis is also pathogenic to humans.