Intestinal parasites of dogs on the Galapagos Islands

Survey of Gastrointestinal Parasites and Lungworms in Cats and Dogs from Terceira and São Miguel Islands, Azores

Parasitic diseases can affect animal health and welfare, and they may also constitute a danger to public health, particularly in island ecosystems. Fecal samples were collected from 205 dogs and 115 cats on the islands of São Miguel and Terceira, Azores archipelago (Portugal), using the Willis flotation technique and modified Baermann method, for further analysis. The overall prevalence of gastrointestinal parasitism in dogs was 53%, with the following results: Ancylostomatidae (hookworms) (42.44%), Trichuris vulpis (17.56%), Toxocara canis (12.68%) and Cystoisospora spp. (4.39%). In cats, the overall prevalence was also 53%, with the following results: Toxocara cati (31.3%), Ancylostomatidae (30.43%), Cystoisospora spp. (14.78%) and Trichuris sp. (0.87%). The prevalence of lungworms was 0.49% in canines and 20.87% in felines, with Angiostrongylus vasorum and Aelurostrongylus abstrusus species being detected in dogs and cats, respectively. The present survey detected a high prevalence of gastrointestinal infection, in both dogs and cats, probably because the samples came mainly from kennels and catteries and due to the peculiar climatic conditions in this insular territory, with mild temperature and high relative humidity. A considerable prevalence of aelurostrongylosis was also detected (20.87%), so it should be included in the list of differential diagnoses of diseases concerning the respiratory tract in cats of the archipelago.

Diversity and prevalence of gastrointestinal helminths of free-roaming dogs on coastal beaches in Ecuador: Potential for zoonotic transmission

Free-roaming dogs are highly exposed to a range of zoonotic parasites, including helminths, which can be transmitted to humans, particularly in rural tropical settings of developing countries. To evidence the diversity and prevalence of gastrointestinal helminths in the stools of free-roaming dogs on the public Pacific coastal beaches of Ecuador, a cross-sectional study was conducted from August 2021 to August 2022. The sampling beaches are located along the tropical Pacific coastal region. Stools were collected from the ground in containers with 10% formalin and processed using the Ritchie method; eggs were identified under a microscope. A total of 573 stools were examined from 20 beaches; the overall prevalence was 157 (27.4%) for one or more helminths. Ten parasites were identified, nine of which are potentially zoonotic. Ancylostoma spp. was the most prevalent (19.4%), followed by Toxocara spp. (7.2%). Trichuris spp., Dipylidium caninum, Diphyllobothrium spp., Capillaria spp., Dicrocoelium spp., Heterobilharzia americana, Hymenolepis spp. and Spirocerca spp. were also observed. Five of them are reported for the first-time infecting dogs in Ecuador. Hence, we evidenced that Ecuadorian beaches are highly contaminated with the dogs' zoonotic gastrointestinal helminths, posing a great risk to public health. Differences in the presence and prevalence were found in samples of tropical humid and dry climate zones. Therefore, based on our findings, we encourage the implementation of broad antiparasitic treatment and prevention strategies to reduce the zoonotic risk.

The Presence of Dirofilaria immitis in Domestic Dogs on San Cristobal Island, Galapagos

This study's concept was outlined around the principle of conservation medicine in a biodiversity hotspot from the Neotropical realm: the Galapagos Islands. The wildlife balance has been modified by multi-host parasites introduced with some domestic animals (dogs and cats). The endemic and endangered species, the Galapagos sea lion (GSL, Zalophus wollebaeki), has been exposed to pathogens of canine and feline origin that could become a significant conservation problem for this species. One of these potential cases is the filarial heartworm infection, Dirofilaria immitis, which has been reported on other pinnipeds, with fatalities and clinical symptoms. Therefore, this study evaluated the presence of the microfilaria of D. immitis in dogs from Puerto Baquerizo Moreno, San Cristobal Island, where the largest rookery of GSLs lives and where the proximity to domestic dogs is the most intimate compared to other rookeries of the archipelago. Between July and September 2021, 587 blood samples were collected from owned dogs of Puerto Baquerizo Moreno. Overall, 10 dogs (1.7%) were positive for the presence of the microfilaria of D. immitis with a confidence interval of 0.7%-2.8%. No other filarial species were identified. Significant differences in prevalence between different dog categories were observed only for the age (p = 0.001). This study represents the first report of D. immitis, the agent of canine heartworm disease, in dogs from San Cristobal Island. Hence, the presence of the microfilaria of D. immitis in the blood of dogs could increase the risk of infection to which the GSL is exposed in the region.

Intestinal parasites and risk factors in dogs and cats from Rio de Janeiro, Brazil

The urban populations of pets, mainly dogs and cats, have been growing in recent years and, consequently, human-animal relationships have become increasingly closer. However, pets are vulnerable to infection by various parasites, as well are their owners due to the zoonotic potential of these agents. This study aimed to assess the frequency and risk factors of intestinal parasites in dogs and cats attended at the Municipal Institute of Veterinary Medicine Jorge Vaitsman, Rio de Janeiro, Brazil, as well as georeferencing the parasitized animals. A total of 608 animals (400 dogs and 208 cats) were enrolled from August 2017 to November 2018. Fecal samples were obtained from the animal's rectum during clinical examination. In addition, the owners of the enrolled dogs and cats were asked to complete an epidemiological questionnaire with questions about the animals' general information, lifestyle, and handling. Fecal samples were subjected to sedimentation and centrifugal-flotation in sucrose solution techniques. The frequencies of intestinal parasites total in dogs and cats were 11.3% and 24.5%, respectively, with hookworms being the most detected parasites in dogs (8.3%) and Dipylidium caninum in cats (12.5%). Sex was the only variable that showed statistical differences in the canine population males being more often infected than female (p < 0.05), while street access was associated with parasitic infections in cats (p < 0.05). The results obtained in this study demonstrate the need to control parasitic infections in domiciled dogs and cats in different municipalities in the metropolitan region of the state of Rio de Janeiro, including residents in the northern, western and central areas.

Immunogenicity and protection induced by recombinant Toxocara canis proteins in a murine model of toxocariasis

Toxocariasis, a natural helminth infection of dogs and cats caused by Toxocara canis and T. cati, respectively, that are transmitted to mammals, including humans. Infection control is based currently on periodic antihelmintic treatment and there is a need for the development of vaccines to prevent this infection.

MATERIALS AND METHODS

Eight potential vaccine candidate T. canis recombinant proteins were identified by in silico (rTcGPRs, rTcCad, rTcVcan, rTcCyst) and larval proteomics (rTES26, rTES32, rMUC-3 and rCTL-4) analyses. Immunogenicity and protection against infectious challenge for seven of these antigens were determined in a murine model of toxocariasis. C57BL/6 female mice were immunized with each of or combinations of recombinant antigens prior to challenge with 500 T. canis embryonated eggs. Levels of specific antibodies (IgG, IgG1, IgG2a and IgE) in sera and cytokines (IL-5, INF-ɣ and IL-10) produced by antigens-stimulated splenocytes, were measured. Presence of specific antibodies to the molecules was measured in sera of T. canis-seropositive dogs and humans.

RESULTS

All seven molecules were immunogenic in immunized mice; all stimulated significantly elevated levels of specific IgG, IgG1 or IgG2a and six were associated with elevated levels of specific IgE; all induced elevated production of IFN- ɣ and IL-10 by splenocytes, but only the in silico-identified membrane-associated recombinants (rTcCad, rTcVcan, and rTcCyst) induced significantly increased IL-5 production. Vaccination with two of the latter (rTcCad and rTcVcan) reduced larval loads in the T. canis challenged mice by 54.3% and 53.9% (P < 0.0001), respectively, compared to unimmunized controls. All seven recombinants were recognized by T. canis-seropositive dog and human sera.

CONCLUSION

The identification of vaccine targets by in silico analysis was an effective strategy to identify immunogenic T. canis proteins capable of reducing larval burdens following challenge with the parasite. Two recombinant proteins, rTcCad and rTcVcan, were identified as promising vaccine candidates for canine toxocariasis.

Canine vector-borne disease in domestic dogs on Isla Santa Cruz, Galápagos

Vector-borne diseases result in significant morbidity and mortality in domestic dogs in tropical and subtropical regions and also pose a potential threat to wildlife species and humans. Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis (CME), has a high reported seroprevalence in dogs on Santa Cruz in the Galápagos Islands, Ecuador. Veterinary diagnostic and treatment resources are often scarce and clinical follow-up is lacking in the Galápagos. This study evaluated 58 dogs presenting to the Darwin Animal Doctors clinic in the city of Puerto Ayora on Santa Cruz Island during August of 2018. The seroprevalence of E. canis/Ehrlichia ewingii (48.3%), Anaplasma phagocytophilum/Anaplasma platys (12.1%), and Borrelia burgdorferi (0%), as well as the proportion of dogs actively infected with E. canis (12.1%) and E. ewingii (0%), are reported. Active infection was defined as the identification of antigen by PCR. Dogs with a packed cell volume (PCV) ≤ 30% had a 10-fold risk of active infection with E. canis compared to dogs with a PCV ≥ 31% (p = .0124). A PCV cutoff of 30% may be a useful screening tool for active E. canis infection in regions with high Ehrlichia seroprevalence, in the absence of other apparent causes of anemia. Dirofilaria immitis antigen was present in 6.9% of examined dogs, with the highest prevalence in the barrio Las Ninfas. PCR and Sanger sequencing were used to provide the first molecular identification of D. immitis in the Galápagos. This study updates the seropositivity and prevalence data of these canine vector-borne pathogens and highlights the need for continued surveillance in the region.

Gastrointestinal helminths in dog feces surrounding suburban areas of Lower Dir district, Pakistan: A public health threat

Data on environmental contamination of the parasites of zoonotic importance is scarce in Pakistan. Soil contamination with feces of dogs hide infective stages of the parasite represents a health-risk to humans. This study was aimed to assess the eggs of gastrointestinal parasites of stray dogs and household dogs in lower Dir district, Pakistan with special consideration to those that can be spread to humans. One hundred and fifty two stool specimens from (stray dogs=90 and household dogs=62) were collected. The helminth eggs were processed by direct smear method and centrifugation techniques and identified by microscopic examination. Of the total examined dogs 26.8% (n=41 /152) were found to be infected with one or more intestinal parasites. The intestinal helminths detected were Dipylidium caninum (n =18, 11.8%), followed by Toxocara canis (n =16, 10.5%), Taenia spp., (n=10, 6.57%) Ancylostoma caninum (n=6, 3.94), Toxascaris spp., Capillaria spp., and Trichuris vulpis (n=2, 1.31% each) in order of their prevalence. Pattern of infection revealed that 27 (65.8%) dogs have single, 13(31.7%) double and 1(2.43%) triple infection. The stray dogs were highly infected 34.4% (n=31) than house hold dogs 16.1% (n=10). The prevalence of infection with intestinal parasites was significantly different among these two groups (p = 0.0097). This study highlight a severe environmental contamination by frequent parasitic stages infectious to humans. There is a higher risk of zoonotic transmission from dogs which indicate an immediate need for the controlling of these parasites and educating the public to take wise action relating to the parasites and pets.

A Case of Cutaneous Larva Migrans in a Child from Vinces, Ecuador

BACKGROUND Cutaneous larva migrans (CLM) is caused by nematode parasites of the hookworm family of Ancylostomatidae. Ancylostomiasis is a zoonosis found in cats and dogs, and humans are an accidental host. This report presents a case of CLM in an 8-year-old boy, which was due to the zoonotic transmission of Ancylostoma caninum from domestic dogs in an urban area of Vinces, Ecuador, and demonstrates how awareness and early diagnosis contributed to the timely treatment of CLM. CASE REPORT An 8-year-old boy from the urban area of Vinces city in the Los Ríos province of Ecuador presented with a serpiginous palpable lesion on the sole of the right foot, consistent with a diagnosis of cutaneous larva migrans (CLM). He was infected through contact with the soil where canine Ancylostoma larvae were found. Twenty samples of feces were analyzed from the soil, and Ancylostoma larvae were found in 100% of these samples. Also, 120 dog stool samples were examined, and 75 (62.5%) contained Ancylostoma larvae, which were identified using the modified Willis and Baermann method. CONCLUSIONS CLM is a zoonotic disease that can affect the population in endemic areas. In this case, CLM was identified in the sole of the foot of a child. The presence of Ancylostoma larvae were identified in the soil and in the feces of dogs, indicating that the community was exposed to a significant environmental risk from this zoonotic disease.

Molecular phylodiagnosis of Echinococcus granulosus sensu lato and Taenia hydatigena determined by mitochondrial Cox1 and SSU-rDNA markers in Iranian dogs: Indicating the first record of pig strain (G7) in definitive host in the Middle East

Unawareness of canine parasitic diseases among at-risk hosts and an uncontrolled program of stray dog population have caused that zoonotic parasites received great attention in endemic regions of the Middle East. A total of 552 faecal samples were collected between December 2016 to January 2018 from stray (n = 408) and domestic (n = 144) dogs of Iran. All specimens were coproscopically observed following concentration and flotation techniques. Subsequently, the DNAs of taeniid eggs were extracted, amplified, and sequenced by targeting of mitochondrial cytochrome oxidase subunit 1 and small-subunit ribosomal DNA markers. The overall prevalence of canine intestinal parasites found 53.6%. The following parasites and their total frequencies were identified: taeniid (10.5%), Dicrocoelium dendriticum (0.7%), Trichuris vulpis (1.2%), Capillaria spp. (2.3%), Blastocystis spp. (5.2%), Ancylostoma spp. (2%), Eimeria spp. (13.2%), Dipylidium caninum (2.3%), Toxocara canis (3.8%), Giardia spp. (8.5%), and Toxascaris leonina (3.6%). Stray dogs were characterized more likely to be poliparasitized and indicated a higher prevalence of taeniid (10.9%), T. canis (4.4%) Giardia spp. (10.1%) than domestic dogs (P > 0.05). Phylogenetic and sequence analysis of Cox1 and SSU-rDNA indicated a low genetic diversity (Haplotype diversity; 0 to 0.495) in E. granulosus sensu lato G1, G3, G7 genotypes, and Taenia hydatigena. The pairwise sequence distances between G7 isolates showed an intra-diversity of 0.7%-1.5% and identity of 98.5%-100%. The first occurrence of pig strain (G7) from Iranian dogs might have substantial implications in the drug treatment of infected dogs due to the shorter maturation time of G7 compared with G1 genotype. Thus, the preventive strategies should be noticed to determine the risk factors, the importance of applying the hygienic practices, and well adjusting deworming programs for the Iranian dogs and at-risk individuals.

Molecular identification of Ancylostoma species from dogs and an assessment of zoonotic risk in low-income households, São Paulo State, Brazil

Hookworm infection stands out for its worldwide distribution and for its veterinary and public health relevance. Based on copromicroscopic examinations and polymerase chain reaction (PCR) amplification of the ITS1-5.8S-ITS2 region, we assessed, respectively, the prevalence of intestinal parasites and the identification of canine hookworm species in faeces recovered from 278 dogs living in households of an inland municipality of São Paulo State, Brazil. Intestinal parasites were found in 67.3% of dogs and hookworm infection was found at the highest prevalence rate (56.6%), followed by Toxocara canis (11.9%), Isospora spp. (11.9%), Giardia spp. (5.8%), Sarcocystis spp. (4.0%), 'Hammondia-like' (1.4%), Dipylidium caninum (1.1%) and Trichuris vulpis (0.7%). Of 158 samples positive for hookworm eggs, 106 (67.1%) were amplified by PCR and, of those, 88 (55.7%) were successfully sequenced for species identification. Single infections with Ancylostoma caninum and Ancylostoma braziliense were recorded in 61.4% and 12.5%, respectively, and mixed infections were found in 26.1%. The nucleotide sequences of both species showed high identity rates (98-100%) when compared with reference sequences. Although A. caninum was the most prevalent hookworm in the dogs assessed, the occurrence of both A. caninum and A. braziliense in single and/or mixed infections poses a potential risk for the local population in a low-income area, especially children, to acquire cutaneous larva migrans (CLM).

Dog overpopulation and burden of exposure to canine distemper virus and other pathogens on Santa Cruz Island, Galapagos

Dog overpopulation and diseases are hazards to native island species and humans on the Galapagos. Vaccination and importation of dogs are prohibited on the Galapagos. Risk management of these hazards requires the use of science-based risk assessment and risk communication. The objectives of the study reported here were (i) to estimate the human:dog ratio and (ii) the prevalence of and identify exposure factors associated with positive antibody titers to canine distemper virus (CDV) and other pathogens, as well as infection with intestinal parasites in owned dogs on Santa Cruz Island, Galapagos in September 2014. The observed human:dog ratio was 6.148:1 which extrapolates to 2503 dogs (two times more than a recent dog count conducted by Galapagos Biosecurity Agency in March 2014). The proportion of spayed female dogs (50%) was higher, compared to neutered male dogs (30%) (p=0.04). Prevalence of dogs with positive antibody titers to CDV was 36% (95% CI=26, 46%), to canine parvovirus was 89% (95% CI=82, 95%), and to canine adenovirus was 40% (95% CI=30, 51%). The frequency of seropositive dogs to CDV was lower in urban dogs (26%), compared to rural dogs (53%) (p<0.05). A positive interaction effect between rural residence and spay/neuter status on seropositivity to CDV was observed, which we discuss in this report. Because vaccination is prohibited, the dog population on Santa Cruz is susceptible to an outbreak of CDV (particularly among urban dogs) with potential spill over to marine mammals. Dog's age (1-2 or 3-14 years old, compared to younger dogs), and residence (rural, urban) were associated with positive antibody titers to parvovirus, adenovirus, Ehrlichia spp., or Anaplasma spp., as well as infection with Ancylostoma spp., an intestinal parasite in dogs that can be transmitted to humans, particularly children. These results provide the most comprehensive assessment of dog overpopulation and exposure to CDV and other pathogens on the Galapagos to date.

The prevalence of Giardia infection in dogs and cats, a systematic review and meta-analysis of prevalence studies from stool samples

Giardia has a wide range of host species and is a common cause of diarrhoeal disease in humans and animals. Companion animals are able to transmit a range of zoonotic diseases to their owners including giardiasis, but the size of this risk is not well known. The aim of this study was to analyse giardiasis prevalence rates in dogs and cats worldwide using a systematic search approach. Meta-analysis enabled to describe associations between Giardia prevalence and various confounding factors. Pooled prevalence rates were 15.2% (95% CI 13.8-16.7%) for dogs and 12% (95% CI 9.2-15.3%) for cats. However, there was very high heterogeneity between studies. Meta-regression showed that the diagnostic method used had a major impact on reported prevalence with studies using ELISA, IFA and PCR reporting prevalence rates between 2.6 and 3.7 times greater than studies using microscopy. Conditional negative binomial regression found that symptomatic animals had higher prevalence rates ratios (PRR) than asymptomatic animals 1.61 (95% CI 1.33-1.94) in dogs and 1.94 (95% CI 1.47-2.56) in cats. Giardia was much more prevalent in young animals. For cats >6 months, PRR=0.47 (0.42-0.53) and in dogs of the same age group PRR=0.36 (0.32-0.41). Additionally, dogs kept as pets were less likely to be positive (PRR=0.56 (0.41-0.77)) but any difference in cats was not significant. Faecal excretion of Giardia is common in dogs and slightly less so in cats. However, the exact rates depend on the diagnostic method used, the age and origin of the animal. What risk such endemic colonisation poses to human health is still unclear as it will depend not only on prevalence rates but also on what assemblages are excreted and how people interact with their pets.

Multiple zoonotic parasites identified in dog feces collected in Ponte de Lima, Portugal-a potential threat to human health

Dogs play many roles and their presence within people’s houses has increased. In rural settings dog faeces are not removed from the streets, representing an environmental pollution factor. Our aim was to evaluate the occurrence of environmental contamination with zoonotic intestinal parasites of three groups of dogs in Ponte de Lima, Portugal, with a particular emphasis on Echinococcus granulosus. We collected 592 dog faecal samples from the environment, farm and hunting dogs. Qualitative flotation coprological analysis was performed and the frequency in the positive samples ranged between 57.44% and 81.19% in different groups. We isolated up to four different parasites in one sample and detected seven intestinal parasitic species, genera or families overall. Ancylostomatidae was the most prevalent parasite, followed by Trichuris spp., Toxocara spp., Isospora spp., Dipylidium caninum, Taeniidae and Toxascaris leonina. Taeniidae eggs were analyzed with the PCR technique and revealed not to be from Echinococcus. The parasite prevalence and the diversity of zoonotic parasites found were high, which calls for a greater awareness of the problem among the population, especially hunters. Promoting research at the local level is important to plan control strategies. Health education should be developed with regard to farmers and hunters, and a closer collaboration between researchers, practitioners and public health authorities is needed.

Genetic and morphometric evidence on a Galápagos Island exposes founder effects and diversification in the first-known (truly) feral western dog population

Domesticated animals that revert to a wild state can become invasive and significantly impact native biodiversity. Although dogs can be problematic locally, only the Australasian dingo is known to occur in isolation from humans. Western dogs have experienced more intense artificial selection, which potentially limits their invasiveness. However, feral dogs eradicated from Isabela Island, Galápagos in the 1980s could be the first-known exception. We used DNA and morphometric data from 92 of these dogs to test the hypotheses that (i) these dogs persisted independently of humans for up to a century and a half since descending from a handful of dogs introduced in the early 1800s, vs. (ii) similarly to other western feral dog populations, they reflected continuous recruitment of strays from human settlements on a portion of the Island. We detected one dominant maternal lineage and one dominant paternal lineage shared by the three subpopulations, along with low autosomal genetic diversity, consistent with the hypothesized common origins from a small founder population. Genetic diversity patterns among the three island subpopulations were consistent with stepping-stone founder effects, while morphometric differentiation suggested rapid phenotypic divergence, possibly due to drift and reinforced by selection corresponding to distinct microclimates and habitats on Isabela. Despite the continued presence of free-ranging dogs in the vicinity of settlements on Isabela and other Galápagos Islands, feral populations have not reestablished in remote areas since the 1980s, emphasizing the rarity of conditions necessary for feralization of modern western dogs.

An epidemiological survey on intestinal helminths of stray dogs in Mashhad, North-east of Iran

This research was conducted to determine the prevalence of gastrointestinal helminths in stray dogs in the northeast of Iran, with special attention to those parasites that can be transmitted to human. In this experiment, a total of 72 adult and 18 juvenile stray dogs were collected and necropsied for the presence of helminth parasites from October 2011 to August 2012. The overall prevalence of gastrointestinal helminths was 86 % (95 % CI: 79.2-92.8 %). The observed helminths of the gastrointestinal tract were listed as follows: Toxocara canis (29 %), Toxascaris leonina (7 %), Ancylostoma caninum (2 %), Taenia hydatigena (43 %), Dipylidium caninum (39 %), Echinococcus granulosus (38 %), Mesocestoides lineatus (16 %), Taenia multiceps (11 %), Taenia ovis (3 %). There were no significant differences for the prevalence of gastrointestinal helminths between female (83.6 %) and male (89.7 %) and between young (89 %) and adult (72.2 %) animals. However, the prevalence of E. granulosus, T. hydatigena and D. caninum showed an increasing trend with increasing host age, significantly. Based on our data, it is important to point out the presence of zoonotic agents, namely E. granulosus and T. canis in stray dogs in the investigated area. Due to its impact on public health, appropriate control measures should be taken and it is recommended to determine the most appropriate preventive methods.

Larval development of Toxocara canis in dogs

The parasitic roundworm Toxocara canis is present in dog populations all over the world. Due to its zoonotic potential, this roundworm is of special interest not only for veterinarians, but also for medical practitioners. In the present review, current knowledge of infection routes and the subsequent development of larvae within the canine host is summarised. Furthermore, information about the clinical, pathological, enzymatic, haematological and histopathological changes was collected, giving a broad overview of current knowledge of the infection. Although the data collected over the years give an idea of what happens during the larval development of T. canis, many questions remain open. Nevertheless, it is important that we continue our efforts to further understand the biology of this versatile and compelling parasite and try to improve and optimise strategies to prevent the infection in dogs and thereby to protect humans from this infection.