Exposure to vector-borne pathogens in privately owned dogs living in different socioeconomic settings in Brazil

Vector-borne pathogens in dogs in Egypt: Molecular and immunological insights

Canine vector-borne diseases (CVBD) constitute a significant global health challenge, impacting dogs and posing zoonotic risks to humans. These diseases are transmitted through blood-feeding vectors such as ticks, fleas, and mosquitoes. This study, conducted in Cairo and Giza, Egypt, aimed to assess the prevalence, diversity, and clinical impact of CVBD in both domestic and stray dogs. Using microscopic and molecular diagnostic techniques, several pathogens were identified, including two primary zoonotic blood pathogens, Anaplasma platys and Leishmania spp., as well as other blood pathogens with varying degrees of zoonotic potential, such as Ehrlichia canis (E. canis), Anaplasma phagocytophilum, Anaplasma marginale, Babesia canis vogeli (B. canis vogeli), Hepatozoon canis, and Trypanosoma evansi. Stray dogs exhibited a higher prevalence of infection than domestic dogs, frequently presenting with co-infections. Clinically, infected dogs displayed clinical signs including weight loss, pale mucous membranes, lethargy, and anorexia, with more severe manifestations observed in cases with co-infections, particularly involving B. canis vogeli and E. canis. The immune response in these dogs was marked by elevated levels of inflammatory cytokines, such as tumor necrosis factor-α, interferon-γ, and interleukin-1β, which were significantly higher in symptomatic dogs, indicating a robust immune defense against the pathogens. Furthermore, markers of oxidative stress, including glutathione, malondialdehyde, and nitric oxide, were elevated in infected dogs, suggesting increased cellular damage due to prolonged infection and inflammation. The findings underline the key significance of stray dogs in the transmission and maintenance of CVBD and emphasize the necessity for comprehensive diagnostic, preventive, and control strategies to mitigate the prevalence of these diseases in dog populations and their potential zoonotic impact on human health.

Lyme borreliosis in Brazil: a critical review on the Baggio-Yoshinari syndrome (Brazilian Lyme-like disease)

SUMMARYLyme borreliosis or Lyme disease is the most frequently reported tick-borne disease in the Northern Hemisphere. In countries of the Southern Hemisphere, such as Brazil, since the early 1990s, some researchers have argued for the existence of an autochthonous Lyme-like borreliosis, known locally as the Baggio-Yoshinari syndrome (BYS), an alleged "Brazilian borreliosis" supposedly caused by a different strain of Borrelia burgdorferi and transmitted by hard ticks. Currently, the existence of BYS in Brazil is still accepted by a large part of the human health care workers, scientists, medical societies, and patients. In fact, this alleged "Brazilian borreliosis" has been the tick-borne zoonotic disease with the greatest number of reported cases and published studies in Brazil during this century, second only to Brazilian spotted fever. In this manuscript, we reviewed all manuscripts directly related to BYS that have been published in Brazil during the last 35 years. This analysis included 199 individual human cases that have been reported in Brazil since 1989, plus multiple studies on ticks, domestic, and wild animals. Our revision aimed to provide a critical opinion on whether the current published works allow healthcare workers, public health agencies, and patients to accept the existence of Lyme disease, BYS, or other Lyme borreliosis-related disease in Brazil. For this purpose, we evaluated the strengths and weaknesses of each published study, considering the diagnostic methods used, such as serological, microbiological, and molecular analyses. Based on these evaluations, we conclude that there is not enough evidence to support the occurrence of Lyme borreliosis in Brazil or that BYS (Brazilian Lyme-like disease) is caused by a bacterium of the genus Borrelia. This assumption is based on the inaccuracy, unreliability, and misinterpretation of the different diagnostic methods that have been used in Brazil. Recognizing the lack of technical evidence for the occurrence of Lyme borreliosis in Brazil has highly relevant implications. For example, it becomes imperative to raise awareness among the country's medical profession, as they have adopted unnecessary and extreme therapies recommended for patients with a supposed borrelial infection, including BYS, in Brazil. Finally, the technical analyses carried out in this study could be applied to other countries in the Southern Hemisphere (e.g., Argentina, South Africa, Australia), where cases classified and alleged as Lyme disease have been reported.

Canine vector-borne infections of working dogs of the Sri Lanka Air Force, and free roaming, and privately owned dogs

Canine vector-borne infections (CVBIs) are a global health problem. The military working dogs of Sri Lanka die at an early age, and CVBIs have been a leading speculated cause. We examined CVBIs in the working dogs of the Sri Lanka air force (SLAF) and free-roaming dogs (FRDs) and privately owned dogs (PODs) country-wide. Giemsa-stained smears were prepared and conventional PCR-positive DNA was subjected to sequencing and phylogeny. Of the 668 dogs sampled, 212 (31.7%) had one or more CVBIs. The prevalence of infections among the FRDs (40.0%) was significantly higher than SLAF working dogs (30.0%; χ2 = 10.5216; p = 0.0012) and PODs (26.2%; χ2 = 5.3414, p = 0.0208) but not between SLAF dogs and PODs (χ2 = 1.7655, p = 0.1838). Many infected dogs were asymptomatic (57.4%), which was higher among the FRDs. Seven infectious agents were identified: Babesia gibsoni, B. canis, Ehrlichia canis, Anaplasma platys, Leishmania sp., Hepatozoon canis, and filaria worms. The most common infection was B. gibsoni (13.8%), followed by E. canis (9.9%). Three tick species: Rhipicephalus linneai, Rhipicephalus haemaphysaloides and Haemophysalis bispinosa were found infesting the dogs. The SLAF dogs were thoroughly quarantined upon arrival, but the infection prevalence was similar to PODs.

The Distribution, Diversity, and Control of Dirofilariosis in Brazil: A Comprehensive Review

Brazil's extensive coastline, tropical and subtropical climate, and well-preserved environment represent a conducive setting for dirofilariosis, a zoonotic mosquito-borne disease. Although this condition has long been recognised in the country, it has been relatively under-studied, and it is currently considered to be an emerging disease. Diagnosis, treatment, and control remain challenging due to the extensive gaps in knowledge. In order to help address this issue, this review aims to (i) summarise the available literature on the distribution of Dirofilaria spp. in Brazilian dogs over the last decade, (ii) review case reports of dirofilariosis in cats, wild animals, and humans over the last twenty years, and (iii) highlight the benefits of taking a One Health approach to managing this disease. While there have been several prevalence studies in dogs, disease distribution is poorly characterised in cats, and little is known about the occurrence of the parasite in wildlife. Human cases are sporadically reported, and no large-scale studies have been undertaken to date. Evidence indicates that Dirofilaria immitis is the main species circulating in Brazil, although Dirofilaria repens has also been detected. Molecular studies have also suggested the circulation of a highly virulent form of D. immitis, which may be genetically distinct from those of the Old World. A programme of epidemiological, ecological, genomic, and pathogenicity-based studies is required to quantify the impact of dirofilariosis in Brazil on both veterinary and public health and to inform others on its control.

Filarial Nematodes in Dogs from the Northeast Region of Brazil

PURPOSE

Medical and veterinary filarial nematodes are transmitted by blood-feeding vectors. In dogs, these parasites are mainly represented by nematodes in which microfilariae dwell in the blood (Dirofilaria spp. and Acanthocheilonema spp.) or skin (Cercopithifilaria spp. and Onchocerca lupi). The aim of this study was to determine the prevalence of these filarial infections in dogs residing in a touristic, heavily populated location in the northeastern region of Brazil.

METHODS

Blood samples (n = 245) were assessed by a modified Knott test, followed by a qualitative ELISA test (SNAP® 4Dx® Plus, IDEXX Laboratory, Westbrook, Maine, USA) for the detection of antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato, Ehrlichia spp. and antigens of Dirofilaria immitis. Skin samples (n = 71) were microscopically examined and molecularly assessed through a PCR targeting the 12 S rRNA gene.

RESULTS

Microfilariae and antigen of D. immitis were detected simultaneously in 15 (6.1%; 95% CI = 3.7-9.8) animals. Nine animals (3.6%; 95% CI = 1.9-6.8) were D. immitis antigen positive but microfilariae negative and nine other animals (3.6%; 95% CI = 1.9-6.8) were microfilariae positive but D. immitis antigen negative. D. immitis positive dogs were found in four different municipalities. No filarioids were detected in the skin after microscopical and molecular analyses.

CONCLUSION

Data from this study demonstrate that D. immitis is the main filarial nematode infecting dogs in coastal areas in northeastern Brazil. Based on the potential risk of infection in which animals are submitted, it is essential to perform tests to detect microfilariae and D. immitis antigen. Preventive measures must be adopted by using microfilaricidal compounds and anti-feeding insecticides to prevent canine infection.

Gastrointestinal Parasites in Owned Dogs in Serbia: Prevalence and Risk Factors

Dogs are the most popular pets worldwide. Close contact between dogs and people increases the risk of transmission of various zoonotic parasitic infections. Given the importance of veterinary medicine in preserving the One Health concept, the aim of this research was to identify intestinal parasites that may have zoonotic potential and to evaluate risk factors (individual and environmental). The research was conducted in Serbia in 2022 and 2023 on 382 owned dogs, using qualitative methods of coprological examination with a concentration on parasitic elements. The overall prevalence of intestinal parasites was 62.6%, with the following detected: protozoa: Cystoisospora spp. (9.2%), Sarcocystis spp. (4.5%), Neospora caninum/Hammondia spp. (3.7%), Giardia intestinalis (11.8%); nematoda: Toxocara canis (11.5%), Toxascaris leonina (4.2%), family Ancylostomatidae (38.0%), Trichuris vulpis (21.5%), Capillaria spp. (10.5%); trematoda: Alaria alata (1.6%) and cestodes from the Taeniidae family (1.3%). Factors like age, size and coat length, as well as the way of living, attitude and diet were linked to a significantly higher (p < 0.05) prevalence of intestinal parasites. Based on the results of coprological diagnostics, this research indicates the importance of educating dog owners, conducting routine parasitological tests on their pets and regular deworming strategies.

Prevention of heartworm infection in dogs using a combination of moxidectin, imidacloprid and praziquantel: evidence from a randomized clinical trial

The aim of this study was to evaluate the efficacy of a topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% for the prevention of Dirofilaria immitis (Leidy, 1856) infection in dogs. For this purpose, a randomized and controlled clinical trial was conducted between August 2021 and October 2022, in the municipality of Goiana, state of Pernambuco, north-eastern Brazil, where heartworm is highly prevalent. Of the 213 dogs initially sampled (baseline), 68 (31.9%) were positive for adult antigens (SNAP 4Dx Plus, Idexx) and/or microfilariae (modified Knott's test). On day 0, 140 negative dogs were randomly included in the treatment and control groups, 70 animals each. During the study, 60 dogs (34 treated and 26 untreated) were removed for different reasons. At the end of the study (day 360 ± 2), 36 treated and 44 untreated were sampled and included in the efficacy calculation. The efficacy against the development of adults and microfilariae was 84.7%, with only one treated dog being positive for adult antigens but negative for microfilariae. On the other hand, eight untreated dogs were positive for adult antigens and/or microfilariae, resulting in a significant difference in the number of positives between groups (Chi-square test = 4.706, df = 1, P = 0.0301). Remarkably, the efficacy against the appearance of D. immitis microfilariae was 100% (i.e., all treated dogs negative) and three untreated dogs were positive for microfilariae. The topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% significantly reduced the risk of D. immitis infection in treated dogs as compared with untreated dogs, in a highly endemic area in north-eastern Brazil.

Dirofilaria immitis in pet dogs from the metropolitan area of the Colombian Caribbean

A cross-sectional study was carried out to determine the frequency and factors associated with Dirofilaria immitis infection in pet dogs in the metropolitan area of the Colombian Caribbean (northern Colombia). A total of 173 dogs were analyzed by a commercial rapid immunochromatographic test (RIT) and a nested PCR of the cytochrome oxidase subunit I gene, in parallel. Ninety-two (53.2%) of the dogs showed positive results to the RIT, while 59 (34.1%) animals had D. immitis DNA by PCR. Positivity to one or both diagnostic techniques was detected in 104 (60.1%; CI95%: 53.8-67.4) of the sampled dogs. In PCR-positive dogs, phylogenetic analyses evidenced high nucleotide identity (100%) with sequences previously obtained from mosquitoes, dogs and other mammals in different countries. Exercise intolerance (p = 0.002; OR: 2.33; CI95%: 1.37-3.96) and thrombocytopenia (p = < 0.001; OR: 1.95; CI95%: 1.11-3.43) were the main factors associated with D. immitis infection in dogs. The high frequency of D. immitis in dogs indicates a wide distribution of this parasite in the metropolitan area of the Colombian Caribbean, which can be of animal and public health concern. Our results highlight the need to combine different methods to increase the diagnostic accuracy of D. immitis.

Heartworm adulticide treatment: a tropical perspective

Dirofilaria immitis (the canine heartworm) is widespread in the tropics, with prevalence surpassing 30% in high-risk areas. In addition to the suitable climatic conditions that favour mosquito abundance and filarial larva development, there is low compliance with the recommended year-round use of preventives in these transmission hotspots. This represents a major concern, considering that melarsomine (first-line heartworm adulticide) is unavailable in several tropical countries, resulting in the so-called slow-kill protocol being the only available adulticide treatment option. In this article, the members of TroCCAP (Tropical Council for Companion Animal Parasites) review the current distribution of heartworm in the tropics and the availability of melarsomine, and discuss alternatives for the management of heartworm infections in dogs.

Molecular detection of vector-borne pathogens in semen from dogs in southeastern Brazil

Vector-borne pathogens (VBPs) are primarily transmitted by arthropod vectors, but secondary ways of transmission have been described, including via venereal route. Nonetheless, there is still limited research on possible sexual transmission of VBPs in dogs. We molecularly investigated the presence of vector-borne pathogens in semen from dogs living in an area where these agents are endemic. Upon PCR testing, seven out of 22 (31.8%) semen samples tested positive for at least one VBP, whereas simultaneous positivity to two or more pathogens was detected in three (13.6%) dogs. Among pathogens detected in semen, Trypanosoma cruzi (n = 1) and Leishmania infantum (n = 3) were identified to species level by restriction fragment length polymorphism analysis. Attempts to sequence PCR products from other pathogens were unsuccessful, but coupled epidemiological and molecular data suggest the presence of Anaplasma platys (n = 5), Babesia vogeli (n = 1) and Ehrlichia canis (n = 1) in semen from dogs. Further experimental studies would be needed to confirm the sexual transmission hypothesis for these VBPs and also the possible implications of these findings for canine reproduction.

Vector-borne pathogens of zoonotic concern in dogs from a Quilombola community in northeastern Brazil

Canine vector-borne pathogens (CVBPs) comprise a group of disease agents mainly transmitted by ticks, fleas, mosquitoes and sand flies. In this study, we assessed the presence of CVBPs in an Afro-descendent community (Quilombola) of northeastern, Brazil. Dog blood samples (n = 201) were collected and analyzed by rapid test for the detection of antibodies against Leishmania spp., Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi sensu lato (s.l.), and antigens of Dirofilaria immitis. In addition, polymerase chain reactions were performed for Anaplasmataceae, Babesia spp., Hepatozoon spp., Rickettsia spp. and B. burgdorferi s.l. Overall, 66.7% of the dogs scored positive to at least one pathogen at serological and/or molecular methods. Antibodies against Ehrlichia spp. were the most frequently detected (57.2%; n = 115/201), followed by Anaplasma spp. (8.5%; n = 17/201), Leishmania spp. (8.5%; n = 17/201) and B. burgdorferi s.l. (0.5%; n = 1/201). For D. immitis, 11 out of 201 (5.5%) animals scored positive. At the molecular analysis, 10.4% (n = 21/201) of the samples scored positive for Babesia spp./Hepatozoon spp., followed by Anaplasmataceae (5.0%; n = 10/201) and Rickettsia spp. (3.0%; n = 6/201). All samples were negative for B. burgdorferi s.l. Our data demonstrated the presence of CVBPs in the studied population, with a high seropositivity for Ehrlichia spp. In addition, considering the detection of zoonotic pathogens in dogs and their relationship with people from Quilombola communities, effective control strategies are advocated for minimizing the risk of infection in this socially vulnerable human population and their pets.

Exploring IL-17 gene promoter polymorphisms in canine leishmaniasis

Proinflammatory cytokine secretion determines the infection course in leishmaniasis. The immunopathology of canine leishmaniasis (CanL) caused by Leishmania infantum is characterized by low Leishmania-specific IFN-γ and IL-17 production. Mutations in the human IL-17 gene promoter alter cytokine expression and may increase the susceptibility of humans to some infectious diseases. In this study, we correlated canine IL-17 single nucleotide polymorphisms (SNPs) with anti-Leishmania IgG levels, parasite load and external clinical signs in dogs naturally exposed to L. infantum in Brazil. A higher frequency (Chi-square test: X²= 5.378, df= 1, P= 0.020) of major alleles was observed among dogs showing no external clinical signs attributable to Leishmania infection. A high proportion of A allele carriers (mutant) were observed among dogs with high antibody levels, although differences were not statistically significant (Chi-square test: X²= 4.410, df= 4, P= 0.353), as compared to dogs with low antibody levels. In general, the association of canine IL-17 SNPs with disease expression or disease exasperation did not reach enough statistical power to allow the use of these mutations as prognostic markers. This knowledge may pave the way for further investigations on the genetic aspects of CanL and its immunotherapy.

Prevalence and risk factors for Dirofilaria immitis in dogs from Laguna, Santa Catarina, Brazil

Dirofilaria immitis is a nematode found worldwide and able to infect several species, such as dogs, cats and, under rare circumstances, humans. In Brazil, most of the infections are related to coastal areas. The present study aimed at determining Dirofilaria immitis prevalence and evaluating the possible risk factors for infection in dogs, in Laguna, Santa Catarina, Brazil. Blood samples from 238 dogs were collected and a questionnaire was applied to the owners in order to obtain general information about the animals (age, gender, breed, coat color, home location (region), the use of dewormer/ectoparasiticide drugs, habits and behavior, roaming, insect control and the owner's knowledge about the disease). Samples were processed by blood smear techniques, modified Knott's test, immunochromatographic assay and PCR. Data were statistically analyzed by χ2 and OR. 4.62% was the overall prevalence of canine dirofilariasis and the suburb of Bananal, in Laguna, showed the highest prevalence (18.8%) when comparing with other regions (p < 0.05). However, there was no other significant factor related to the prevalence of D. immitis infection. Thus, the research have confirmed the presence of D. immitis in Laguna region, with a high prevalence in Bananal suburb, a dense forested area.

Occurrence of tick-borne pathogens in dogs in a coastal region of the state of Ceará, northeastern Brazil

The aim of this study was to determine the occurrence of tick-borne pathogens (Ehrlichia canis, Babesia vogeli, Hepatozoon spp. and Rickettsia spp.) in dogs in Vila de Jericoacoara, coastal region of Ceará, Brazil. Blood samples were collected from 153 animals and analyzed using molecular and serological methods. Sixty animals were found to be infected or exposed to at least one of the pathogens studied. Babesia vogeli was the most prevalent pathogen (15%), followed by E. canis (13.7%) and Hepatozoon spp. (11.8%), which was identified as Hepatozoon canis through sequencing. Twenty dogs (13%) were seroreactive to Rickettsia spp. Rhipicephalus sanguineus sensu lato was observed on 11.8% of the animals. There were associations between age (< 3 years old) and positivity for B. vogeli, and between habitation (stray dogs) and positivity for H. canis. There were also associations between anemia and infection with H. canis, and between leukopenia and exposure to Rickettsia spp. No association was detected between clinical alterations and infection with or exposure to the pathogens studied. The results confirmed that pathogens of veterinary importance are circulating in northeastern Brazil and showed that dogs are exposed to Rickettsia species with zoonotic potential, thus indicating a need for vector control measures.

Molecular epidemiology and prevalence of babesial infections in dogs in two hyperendemic foci in Brazil

Babesial parasites are some of the most ubiquitous blood pathogens and consequently have considerable worldwide veterinary impact. Dogs living in the tropics are highly exposed to babesial parasites, particularly to Babesia vogeli. Limited data on the seroprevalence and molecular prevalence of Babesia spp. in dogs are available in Latin America. We conducted a cross-sectional study combining serological and molecular tests to estimate the seroprevalence and molecular epidemiology of Babesia spp. infections in dogs in two hyperendemic foci in Brazil. A total of 630 privately owned dogs (417 from Goiana municipality, Pernambuco state, north-eastern Brazil, and 213 from São Joaquim de Bicas municipality, Minas Gerais state, south-eastern Brazil) were sampled and molecularly and serologically tested for Babesia spp. Overall, 519 dogs (82.4%) presented detectable IgG antibodies against Babesia spp., and seropositivity was significantly higher in dogs older than 1 year. Molecularly, 34 dogs (5.4%) were positive for a ~ 200 bp fragment of the 18S rRNA gene of Babesia spp. and 88 (14.0%) for a longer fragment (~ 450 bp) of the same gene of Babesia spp. and other protozoa. The 18S rRNA gene sequences generated herein corresponded to B. vogeli (n = 52) or Hepatozoon canis (n = 20). This study confirms a high level of exposure to B. vogeli in two areas of Brazil and highlights that most of the dogs living in these areas are infected during the course of their life, reflected by increased seroprevalence in older dogs. Increased awareness and prevention of tick-borne protozoa infections in dogs from Brazil and Latin America are urgently needed.

Frequency of co-seropositivities for certain pathogens and their relationship with clinical and histopathological changes and parasite load in dogs infected with Leishmania infantum

In canine leishmaniosis caused by the protozoan Leishmania infantum, little is known about how co-infections with or co-seropositivities for other pathogens can influence aggravation of this disease. Therefore, the objectives of this study were to evaluate the frequency of co-infections with or co-seropositivities for certain pathogens in dogs seropositive for L. infantum and their relationship with clinical signs, histological changes and L. infantum load. Sixty-six L. infantum-seropositive dogs were submitted to clinical examination, collection of blood and bone marrow, culling, and necropsy. Antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato, Ehrlichia spp. and Toxoplasma gondii and Dirofilaria immitis antigens were investigated in serum. Samples from different tissues were submitted to histopathology and immunohistochemistry for the detection of Leishmania spp. and T. gondii. Quantitative real-time PCR was used to assess the L. infantum load in spleen samples. For detection of Coxiella burnetii, conventional PCR and nested PCR were performed using bone marrow samples. All 66 dogs tested positive for L. infantum by qPCR and/or culture. Fifty dogs (76%) were co-seropositive for at least one pathogen: T. gondii (59%), Ehrlichia spp., (41%), and Anaplasma spp. (18%). Clinical signs were observed in 15 (94%) dogs monoinfected with L. infantum and in 45 (90%) dogs co-seropositive for certain pathogens. The L. infantum load in spleen and skin did not differ significantly between monoinfected and co-seropositive dogs. The number of inflammatory cells was higher in the spleen, lung and mammary gland of co-seropositive dogs and in the mitral valve of monoinfected dogs. These results suggest that dogs infected with L. infantum and co-seropositive for certain pathogens are common in the region studied. However, co-seropositivities for certain pathogens did not aggravate clinical signs or L. infantum load, although they were associated with a more intense inflammatory reaction in some organs.

Prevalence of Dirofilaria immitis in shelter dogs in Bucaramanga metropolitan area, Colombia

The heartworm Dirofilaria immitis is the causative agent of cardiopulmonary dirofilariosis in dogs and cats and also infects humans. The current knowledge about this parasite in South America is scarce compared to North America and Europe. Nevertheless, this parasite has been reported in some regions of Colombia. The objective of this study was to determine the prevalence and risk factors associated with D. immitis infection in shelter dogs from Bucaramanga metropolitan area. We performed a cross-sectional study using blood samples from shelter dogs. Microfilariae testing of whole blood included a blood smear and modified Knott's test. Antigen testing of serum was performed using the Anigen Rapid HW Ag Test Kit 2.0 ®. A descriptive analysis and univariable logistic regression analysis were applied. A total of 207 whole blood samples, from 7 shelters dogs in the Bucaramanga metropolitan area, were utilized. The overall prevalence of D. immitis observed in shelter dogs in the Bucaramanga metropolitan area by blood smears and modified Knott's test was 6.3% (13/ 207) and 0.5% (1/207) by immunochromatography test kit. Regarding the prevalence by municipalities, there was a statistical association (P < .05), indicating that the prevalence was higher in dogs in Girón municipality. Likewise, there was a statistical association (P < .05) between the prevalence with respect to heartworm knowledge and mosquito control. For prevalence by gender, age group, dog breed, and hair length, there was no statistical association (P > .05). For Girón municipality there was a 7.1 times (OR = 7.1; CI95% 0.8-59.2; P < .05) increased infection risk. This study provides current data and the first known report of the prevalence of D. immitis microfilaremia and antigenemia in shelter dogs in the Bucaramanga metropolitan area, and these results could be useful for designing new control measures for this infection. We observed that the prevalence of both microfilaremia and antigenemia was significantly lower in these sampled dogs compared to previous reports.

Vector-borne pathogens in dogs from Guatemala, Central America

Vector-borne pathogens (VBPs) of dogs have been extensively studied worldwide, though scientific information for some countries, as is the case for Guatemala, is almost nonexistent. From 2012 to 2015, 975 dogs residing in different departments of Guatemala were sampled and screened using a rapid ELISA for detecting antigen of Dirofilaria immitis and antibodies against Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi. Out of 975 samples analyzed, 46.4% (n = 452) scored positive for at least one pathogen, with D. immitis being the most prevalent (29.7%), followed by Ehrlichia spp. (11.5%) and Anaplasma spp. (5.1%). None of the dogs were positive to B. burgdorferi. Co-infections were observed in 18.1% (n = 176) of dogs, with the simultaneous detection of D. immitis and Ehrlichia spp. being most common. The frequency of VBPs was higher in the department of Santa Rosa (southeast coast of Guatemala), which has a tropical savanna climate. In this region, 59.7% of the dogs surveyed were infected with D. immitis. Our results suggest that the prevalence of VBPs in dogs in Guatemala may be affected by the climate, with dogs living in the southeast coast being at higher risk, as compared to other regions studied. Increased awareness regarding the risk of VBPs in dogs in Guatemala is advocated and the adoption of preventive strategies should be encouraged.

TroCCAP recommendations for the diagnosis, prevention and treatment of parasitic infections in dogs and cats in the tropics

The Tropical Council for Companion Animal Parasites Ltd. (TroCCAP) is a not-for-profit organisation whose mission is to independently inform, guide and make best-practice recommendations for the diagnosis, treatment and control of companion animal parasites in the tropics and sub-tropics, with the aim of protecting animal and human health. In line with this primary mission, TroCCAP recently developed guidelines for the diagnosis, treatment and control of feline and canine parasites in the tropics. The development of these guidelines required unique and complex considerations to be addressed, often inapplicable to developed nations. Much of the tropics encompass middle-to-low income countries in which poor standards of environmental hygiene and large populations of stray dogs and cats coexist. In these regions, a range of parasites pose a high risk to companion animals, which ultimately may place their owners at risk of acquiring parasitic zoonoses. These considerations led to the development of unique recommendations with regard, for example, to deworming and endoparasite testing intervals for the control of both global and 'region-specific' parasites in the tropics. Moreover, the 'off-' or 'extra'-label use of drugs for the treatment and control of parasitic infections is common practice in many tropical countries and many generic products lack manufacturers' information on efficacy, safety, and quality control. Recommendations and advice concerning the use of such drugs and protocols are also addressed in these guidelines. The formation of these guidelines is an important first step towards improving the education of veterinarians specifically regarding best-practice for the diagnosis, treatment and control of canine and feline parasites in the tropics.

Overview on Dirofilaria immitis in the Americas, with notes on other filarial worms infecting dogs

Canine dirofilariosis in the Americas is primarily caused by Dirofilaria immitis, a mosquito-borne filarial worm infecting dogs, which may also infect and cause disease in other mammalian hosts, including humans. Morphological and molecular evidence gathered in the past decades suggest that other Dirofilaria spp. may infect dogs in the American continent, though the actual taxonomic identity of them still needs to be elucidated. In addition, filarial worms belonging to distinct genera have also been reported in dogs in this part of the world, including Acanthocheilonema reconditum, Cercopithifilaria bainae, and Onchocerca lupi. Among these, O. lupi is a species of major clinical significance, which has been reported not only in dogs, but also in cats and humans in North America. The present article provides a current overview on canine dirofilariosis in the Americas, with notes on other filarial worms infecting dogs. It also provides some insights into outstanding research questions that should be responded to fill some of the several knowledge gaps related to this group of parasites in this continent.

Prevalence and incidence of vector-borne pathogens in unprotected dogs in two Brazilian regions

Background

Various vector-borne pathogens (VBPs) affect dogs worldwide, with their diversity and force of infection being usually higher in the tropics. Cross-sectional studies have been conducted to investigate the prevalence of VBPs in dogs, but data from longitudinal studies are scarce. Herein, we assessed the prevalence and the year-crude incidence (YCI) of Leishmania spp. and other VBPs in privately-owned dogs from two geographical regions of Brazil.

Methods

A total of 823 dogs were initially screened for Leishmania spp. by both serology and polymerase chain reaction (PCR). From the negatives, 307 (103 from São Joaquim de Bicas, Minas Gerais, and 204 from Goiana, Pernambuco) were randomly selected for the longitudinal study. These dogs were tested for various VBPs at baseline, after 8 and 12 months.

Results

Out of 823 dogs initially screened, 131 (15.9%) were positive for Leishmania spp. Out of the 307 dogs enrolled in the longitudinal study, 120 (39.1%) were lost for different reasons (e.g. animal death, owner decision, and lost to follow-up). In São Joaquim de Bicas, the baseline prevalence and YCI were as follows: 16.5% and 7.1% for Anaplasma spp.; 81.6% and 100% for Babesia spp.; 0% and 1.3% (only one faint positive) for Dirofilaria immitis; 37.9% and 22.9% for Ehrlichia spp.; 19.5% and 43.8% for Leishmania spp. In Goiana, the baseline prevalence and YCI were as follows: 45.1% and 38.3% for Anaplasma spp.; 79.9% and 96.0% for Babesia spp.; 36.3% and 39.8% for D. immitis; 64.7% and 58.5% for Ehrlichia spp.; 14.7% and 19.6% for Leishmania spp. Anti-Borrelia burgdorferi antibodies were not detected in any of the samples tested herein. The prevalence and YCI of Anaplasma spp., D. immitis and Ehrlichia spp. were significantly higher in Goiana. In contrast, the YCI of Leishmania spp. infection was significantly higher in São Joaquim de Bicas.

Conclusions

We confirmed a high prevalence and YCI of various VBPs among privately-owned dogs in two geographical regions of Brazil. Our data also indicate that the risk of infection varies significantly for individual VBPs and between the regions, which may be related to several factors that are still poorly understood.

The global status of Dirofilaria immitis in dogs: a systematic review and meta-analysis based on published articles

Dirofilaria immitis is a parasitic filarial nematode responsible for heartworm disease in domestic as well as wild canines and felines and pulmonary or cutaneous infections in humans. This systematic review and meta-analysis aimed to evaluate the status of D. immitis in dogs based on available literature. Four English language databases (ISI Web of Science, Scopus, PubMed and Science Direct) containing data on D. immitis prevalence in dogs were thoroughly searched resulting in the inclusion of 193 studies. The findings revealed that the pooled and weighted prevalence of D. immitis infection in dog population based on published papers throughout the world was 10.91% (95% CI=10.18-11.65). In addition, subgroup analysis based on meta-regression revealed that a significant difference between the pooled and weighted prevalence of D. immitis in dogs and country (β =0.14, P=0.049). Given the relatively high prevalence of D. immitis infection in dogs and its adverse effects, it is suggested that to perform more research on the prevention and control of dirofilariasis infection in dogs worldwide.

Mosquito diversity and dog heartworm prevalence in suburban areas

Background

Urbanization is occurring rapidly on a global scale and is altering mosquito communities, creating assemblages that are characteristically less diverse. Despite high rates of urbanization and ample examples of vector-borne diseases transmitted by multiple species, the effects of urbanization-driven mosquito diversity losses on disease transmission has not been well explored. We investigated this question using the dog heartworm, a filarial parasite vectored by numerous mosquito species.

Methods

We trapped host-seeking mosquitoes in undeveloped areas and neighborhoods of different ages in Wake County, North Carolina, USA, analyzing captured mosquitoes for heartworm DNA. We compared within-mosquito heartworm infection across land-use types by Kruskal–Wallis and likelihood ratio tests. Using zip code level data acquired from dogs in a local shelter, we performed linear regressions of within-host heartworm prevalence by within-mosquito heartworm prevalence as well as by three mosquito diversity measures. We also determined the best predictor of host-level prevalence among models including within-mosquito infection, mosquito diversity and abundance, and socioeconomic status as variables.

Results

Suburban areas had lower within-mosquito heartworm prevalence and lower likelihood of heartworm-positive mosquitoes than did undeveloped field sites, although no differences were seen between suburban and undeveloped wooded sites. No relationships were noted between within-mosquito and within-host heartworm prevalence. However, mosquito diversity metrics were positively correlated with host heartworm prevalence. Model selection revealed within-host prevalence was best predicted by a positive relationship with mosquito Shannon–Wiener diversity and a negative relationship with household income.

Conclusions

Our results demonstrate that decreases in mosquito diversity due to urbanization alter vector-borne disease risk. With regard to dog heartworm disease, this loss of mosquito diversity is associated with decreased heartworm prevalence within both the vector and the host. Although the response is likely different for diseases transmitted by one or few species, mosquito diversity losses leading to decreased transmission could be generalizable to other pathogens with multiple vectors. This study contributes to better understanding of the effects of urbanization and the role of vector diversity in multi-vectored pathosystems.

Performance of recombinant chimeric proteins in the serological diagnosis of Trypanosoma cruzi infection in dogs

BACKGROUND

Dogs are considered sentinels in areas of Trypanosoma cruzi transmission risk to humans. ELISA is generally the method of choice for diagnosing T. cruzi exposure in dogs, but its performance substantially depends on the antigenic matrix employed. In previous studies, our group has developed four chimeric antigens (IBMP-8.1, 8.2, 8.3, and 8.4) and evaluated their potential for diagnosing T. cruzi exposure in humans. For human sera, these chimeric antigens presented superior diagnostic performances as compared to commercial tests available in Brazil, Spain, and Argentina. Therefore, in this study we have evaluated the potential of these antigenic proteins for detection of anti-T. cruzi IgG antibodies in dog sera.

METHODOLOGY/PRINCIPAL FINDINGS

The IBMP-ELISA assays were optimized by checkerboard titration. Subsequently, the diagnostic potential was validated through analysis of ROC curves and the performance of the tests was determined using double entry tables. Cross-reactivity was also evaluated for babesiosis, ehrlichiosis, dirofilariosis, anaplasmosis, and visceral leishmaniasis. Best performance was shown by IBMP-8.3 and IBMP-8.4, although all four antigens demonstrated a high diagnostic performance with 46 positive and 149 negative samples tested. IBMP-8.3 demonstrated 100% sensitivity, followed by IBMP-8.4 (96.7-100%), IBMP-8.2 (73.3-87.5%), and IBMP-8.1 (50-100%). The highest specificities were achieved with IBMP-8.2 (100%) and IBMP-8.4 (100%), followed by IBMP-8.3 (96.7-97.5%) and IBMP 8.1 (89.1-100%).

CONCLUSIONS/SIGNIFICANCE

The use of chimeric antigenic matrices in immunoassays for anti-T. cruzi IgG antibody detection in sera of infected dogs was shown to be a promising tool for veterinary diagnosis and epidemiological studies. The chimeric antigens used in this work allowed also to overcome the common hurdles related to serodiagnosis of T. cruzi infection, especially regarding variation of efficiency parameters according to different strains and cross-reactivity with other infectious diseases.

Home sweet home: sand flies find a refuge in remote indigenous villages in north-eastern Brazil, where leishmaniasis is endemic

BACKGROUND

From 2012 to 2013, an outbreak of cutaneous leishmaniasis by Leishmania braziliensis was detected in indigenous villages located in a remote rural area of Pernambuco state, north-eastern Brazil. Considering that the principal activities of this indigenous community are farming and crop plantation, and also that the outbreak involved many children, we investigated the presence of sand fly vectors inside human houses and also the exposure of dogs to leishmanial parasites. Our general objective was to gather epidemiological data that could indicate the occurrence of a peri-domestic/domestic transmission cycle of L. braziliensis in these indigenous villages.

METHODS

From March 2015 to March 2016, sand flies were collected using light traps in the indoor and immediate outdoor environments in the three indigenous villages that reported the most cutaneous leishmaniasis cases during the 2012-2013 outbreak. Moreover, samples obtained from 300 dogs living in the outbreak villages and two nearby villages were tested by a rapid immunochromatographic test and by a real-time PCR for detecting anti-Leishmania antibodies and Leishmania DNA, respectively.

RESULTS

In total, 5640 sand flies belonging to 11 species were identified. Males (n = 3540) predominated over females (n = 2100). Migonemyia migonei (84.3%) was the most abundant species, followed by Evandromyia lenti (5.5%), Lutzomyia longipalpis (4.1%), Nyssomyia intermedia (1.6%) and Micropygomyia capixaba (1.4%), representing together ~97% of the sand flies collected. Nine out of the 11 species identified in this study were found indoors, including M. migonei, L. longipalpis and N. intermedia, which are proven vectors of Leishmania spp. Out of 300 dogs tested, 26 (8.7%) presented anti-Leishmania antibodies and six (2%) were Leishmania DNA-positive. The level of exposure in dogs living in the indigenous villages where the 2012-2013 outbreak of human CL was detected was almost 2-fold higher than in the two nearby villages (11.0 vs 6.2% for serology and 2.6 vs 1.4% for real-time PCR).

CONCLUSIONS

The results suggest that different sand fly vectors may be adapted to human dwellings, thus increasing the risk of transmission in the indoor and immediate outdoor environments. The adaptation of sand flies to the indoor environment in the studied indigenous villages may be partly explained by the poor housing conditions and the proximity of the houses to crop plantations and forest fragments.

Prevalence of ectoparasite infestations in owned dogs in Kwara State, Nigeria

In Nigeria, dogs are the common companions in many households and, harbor wide range of ectoparasites of severe zoonotic potentials. A cross sectional survey was conducted to examine the prevalence, intensity and risk factors of ectoparasite infestation among the owned dogs in Kwara state, Nigeria. A total of 333 dogs were screened for ectoparasites, and questionnaires were applied to obtain information regarding; age, sex, breeds, coat colour and management practices by dog owners. Two hundred and seventy one (81.4%) dogs were infested with at least one species of ectoparasite and multiple infestations recorded mostly among the female dogs. Six species of ectoparasites of three taxa were identified: ticks (Rhipicephalus sanguineus sensu lato, Haemaphysalis leachii and Amblyomma variegatum), fleas (Ctenocephalides canis and C. felis) and louse (Heterodoxus spiniger). R. sanguineus s.l. was the most prevalent (70.3%) followed by C. felis (42.1%) and H. spiniger (30.0%). Intensities of C. felis, H. spiniger and R. sanguineus s.l infestations were significantly higher in female and younger dogs (p < 0.001). Ectoparasites occurrence varied with breed and coat colour of host. A high prevalence of ectoparasite infestation recorded is at variance with the knowledge of dogs' owners in this study area. Therefore, intervention based on provision of veterinary clinics and prevention and management of parasite infestation in endemic area would mitigate the possible health hazard associated with the ectoparasitic infestation of dogs.

Ehrlichia spp. infection in rural dogs from remote indigenous villages in north-eastern Brazil

Background

Ehrlichia canis is a tick-borne bacterium that causes severe, life-threatening disease in dogs, being more prevalent in tropical and subtropical countries. Randomized studies conducted in Brazil indicate that the prevalence of E. canis infection in dogs ranges from 0.7% to over 50.0%. In a study conducted in northern Brazil, the prevalence was higher in dogs from urban areas, as compared to dogs from rural areas. In the present study, we investigated the exposure to Ehrlichia spp. infection in dogs from remote indigenous villages located in a rural area in north-eastern Brazil.

Methods

From March to June 2015, 300 privately owned dogs were blood sampled and tested by a rapid ELISA and by a conventional PCR in order to detect anti-Ehrlichia spp. antibodies and E. canis DNA, respectively. Additionally, dogs were also tested for anti-Anaplasma spp. antibodies and Anaplasma platys DNA, using the same diagnostic approaches. Positivity was correlated with tick infestation and dogs’ data (gender, age and level of restriction).

Results

Overall, 212 (70.7%) dogs were positive for at least one test targeting Ehrlichia spp. In particular, 173 (57.7%) dogs were positive only by rapid ELISA, 5 (1.7%) only by PCR and 34 (11.4%) were simultaneously positive by both tests. In the same way, 39 (13.0%) dogs presented detectable E. canis DNA in their blood, whereas 18 (6.0%) dogs were A. platys DNA-positive. Coupling serological and PCR data, 63 (21.0%) dogs were simultaneously positive to Ehrlichia spp. and Anaplasma spp. Positivity rates for both Ehrlichia spp. and Anaplasma spp. were higher among dogs more than 1 year of age. Sick dogs were more positive to Ehrlichia spp. as compared to healthy dogs.

Conclusions

Dogs from rural areas in north-eastern Brazil are highly exposed to Ehrlichia spp. infection and positivity rates do not necessarily correlate with current tick infestation load, since only one infected tick bite is needed to get the infection. This reinforces the importance of keeping dogs free of ticks, in order to reduce as much as possible the risk of infection by E. canis and other tick-borne pathogens such as Babesia vogeli, which are usually co-endemic.

Spatial and simultaneous seroepidemiology of anti-Leishmania spp. antibodies in dog owners and their dogs from randomly selected households in a major city of southern Brazil

Although leishmaniasis has been described as a classic example of a zoonosis requiring a comprehensive approach for control, to date, no study has been conducted on the spatial distribution of simultaneous Leishmania spp. seroprevalence in dog owners and dogs from randomly selected households in urban settings. Accordingly, the present study aimed to simultaneously identify the seroprevalence, spatial distribution and associated factors of infection with Leishmania spp. in dog owners and their dogs in the city of Londrina, a county seat in southern Brazil with a population of half a million people and ranked 18th in population and 145th in the human development index (HDI) out of 5570 Brazilian cities. Overall, 564 households were surveyed and included 597 homeowners and their 729 dogs. Anti-Leishmania spp. antibodies were detected by ELISA in 9/597 (1.50%) dog owners and in 32/729 (4.38%) dogs, with significantly higher prevalence (p = 0.0042) in dogs. Spatial analysis revealed associations between seropositive dogs and households located up to 500 m from the local railway. No clusters were found for either owner or dog case distributions. In summary, the seroepidemiological and spatial results collectively show a lack of association of the factors for infection, and the results demonstrated higher exposure for dogs than their owners. However, railway areas may provide favorable conditions for the maintenance of infected phlebotomines, thereby causing infection in nearby domiciled dogs. In such an urban scenario, local sanitary barriers should be focused on the terrestrial routes of people and surrounding areas, particularly railways, via continuous vector surveillance and identification of phlebotomines infected by Leishmania spp.

Level of agreement between two commercially available rapid serological tests and the official screening test used to detect Leishmania seropositive dogs in Brazil

This study compared the level of agreement between two commercially available rapid serological tests and the official screening test used to detect Leishmania seropositive dogs in Brazil. Ninety-five canine sera from a visceral leishmaniasis endemic area were tested by using the official immunochromatographic test (T1; rK28 antigen) based on dual path platform technology, a rapid ELISA (T2; purified Leishmania antigens) and an immunochromatographic test (T3; rK28 antigen) based on lateral flow. There was substantial agreement (Kappa 0.77; 95% confidence interval, CI, 0.62-0.91; P<0.001; observed agreement 90.5%) between T1 and T2, and a fair agreement (Kappa 0.26; 95% CI 0.08-0.43; P<0.001; observed agreement 74.7%) between T1 and T3. Sixteen dogs positive at T1 and T2 were negative at T3. T2 may be a reliable alternative to T1, while T3 could lead to an underestimation of the actual number of seropositive dogs.