The prevalence and distribution of gastrointestinal parasites of stray and refuge dogs in four locations in India

Prevalence of intestinal parasites in street dogs (Canis lupus familiaris) with highlights on zoonosis in Lalitpur, Nepal

BACKGROUND

The presence of intestinal parasites influences the growth and well-being of canids. Additionally, infected dogs and their faeces with considerably higher eggs/oocysts released per gram (epg/opg) of zoonotic parasites contribute to parasitic spillover to humans, domestic animals and sympatric wildlife.

OBJECTIVES

The current study aimed to reveal the prevalence of intestinal parasites (protozoa and helminths) and to list the zoonotically significant parasites in free-roaming street dogs in Lalitpur Metropolitan City, Nepal.

METHODS

Fresh faecal samples (n = 332) were collected from feral dogs of varying ages and sexes and transported to the research laboratory. The copro microscopic examination was carried out via direct wet mount, formalin ethyl acetate sedimentation, saturated salt flotation, acid-fast staining and sporulation techniques.

RESULTS

Coproscopy revealed an overall 95.7% (318/332) prevalence rate with 23 diverse species of intestinal parasites (10 protozoa and 13 helminths). Among them, 5 protozoa and 11 helminths possessed zoonotic potential, and their overall prevalence was 92.5%. Helminth's overall prevalence was double that of the protozoa (87.7% vs. 43%). Polyparasitism was dominant over mono parasitism (79.5% vs. 16.3%), and co-infection of up to seven species of parasites at a time was recorded.

CONCLUSIONS

Urban street dogs harboured a higher prevalence of intestinal parasites that varied with age and sex. Since most of the reported parasites are zoonotic, dog density and parasitic richness indicate a greater spillover risk to humans and domestic animals. Furthermore, this study also provides appropriate 'baseline' data for assessing effective control measures against parasitic infestations among street dogs and controlling their transmission to humans.

General knowledge and practice of household dog owners regarding gastrointestinal parasites in Cebu, Philippines

Background and Aim

Canine gastrointestinal tract (GIT) parasites are of public health and veterinary concern and are harmful to both humans and animals. The risk of transmitting GIT parasites can be minimized depending on dog owners' knowledge and management practices. Therefore, this study aimed to assess dog owners' general knowledge and practices regarding GIT parasites.

Materials and Methods

A structured questionnaire containing 10-point Likert statements was administered to 130 respondents in Cebu, Philippines, to obtain information about their profile (age, sex, civil status, and educational attainment) and data regarding their home environment, number of dogs and other pets owned, and their knowledge and practices regarding canine GIT parasites. These respondents had previously provided canine stool samples for fecalysis.

Results

Most respondents were female (65.4%), 18-24 years old (55.4%), single (71.5%), and educated to college level (49.2%). Housing styles were mostly gated (76.9%), and >50% had a garden. The majority owned 1-3 dogs (56.9%) and did not own any other pets (73.8%). All knew about canine GIT parasites. There was a significant association between GIT parasite positivity in dogs and the owner's sex (p = 0.005). Gastrointestinal parasite positivity was also associated with the owner's knowledge about the transmission of parasites from the mother's milk to her puppies (p = 0.001), canine intestinal parasites potentially causing weight loss, diarrhea, and vomiting (p = 0.001), and dogs potentially becoming infected with parasites from licking or sniffing the soil or grass where other animals have been (p = 0.005). Moreover, there was a significant association between GIT parasite positivity and the owner's practice of daily cleaning of the areas where the dog defecated (p = 0.001), deworming every 6-12 months (p = 0.001), and unfailingly following the vaccination and deworming schedule (p = 0.006). Finally, the summative knowledge and practice level of the owners were significantly associated with GIT parasite positivity (p = 0.001).

Conclusion

This study highlights the need for continuous education of dog owners to maintain good knowledge and practices to prevent GIT parasite infection. Frequent deworming (once a month) of adult dogs is recommended.

Dogs as a source for the spreading of enteric parasites including zoonotic ones in Giza Province, Egypt

To investigate the impact of domestic and stray dogs on the transmission of zoonotic and other parasites to humans in contact with them, fecal samples were collected from 80 domestic dogs that presented at a clinic with health disturbances and 220 randomly selected stray dogs housed in shelters. The parasitological examination of these samples revealed infection by six zoonotic and four non-zoonotic parasites in varying percentages. The zoonotic parasites included Ancylostoma caninum, Toxocara canis, Dipylidium caninum, Echinococcus granulosus, Cryptosporidium species, and Giardia cysts and trophozoites. The other parasites included Toxascaris leonina, Trichuris vulpis, Taenia species eggs, and Isospora canis oocysts. The infection rate was higher in stray dogs (60%) than in domestic dogs (40%). Infected dogs in both groups were generally unhealthy, with poor body condition recorded in 13.8% of domestic dogs and 63.6% of stray dogs. The infection rate was higher (92%) among shelter workers than among domestic dog owners (66.7%). Giardia assemblages A and D from dogs and assemblage A from humans, as well as two isolates of Cryptosporidium canis (C. canis), one from dogs and the other from humans, were submitted in the GenBank with the accession numbers OQ870443, OQ870444, and OQ919265 for Giardia and OQ917532 & OQ915519 for C. canis of dogs & human, respectively. In conclusion, domestic and stray dogs play an essential role in transmitting zoonotic parasites to humans in contact with them, and regular deworming and strict hygienic measures are recommended to minimize their impact on human health.

Prevalence of Gastrointestinal Helminths of Dogs and Associated Factors in Hawassa City of Sidama Region, Ethiopia

A cross-sectional study was carried out in the Sidama region's Hawassa town from March 2021 to July 2021 with the aim of estimating the prevalence and associated factors of dog gastrointestinal helminths. A total of 384 dogs were randomly selected, and their feces were examined using a flotation technique. For data analysis, descriptive statistics and chi-square analyses were employed, and a P-value of less than 0.05 was considered as significant. Accordingly, 56% (n = 215; 95% CI, 49.26-62.66) of dogs had gastrointestinal helminth parasite infection, of which 42.2% (n = 162) had a single infection and 13.8% (n = 53) had a mixed infection. In this study, Strongyloides sp. was the most detected helminth (24.2%), followed by Ancylostoma sp. (15.37%), Trichuris vulpis (14.6%), Toxocara canis (5.73%), Echinococcus sp. (5.47%), and Dipylidium caninum (4.43%). Out of the total sampled dogs tested positive for one or more gastrointestinal helminths, 37.5% (n = 144) were males and 18.5% (n = 71) were females. The total prevalence of helminth infections did not change significantly (P > 0.05) by the gender, age, and breed of dogs. The present study's high prevalence of dog helminthiasis reflects a high occurrence of infection and a concern to the public's health. In light of this conclusion, it is advised that dog owners improve their standards of hygiene. In addition, they should regularly take their animals to veterinary care and frequently administer the appropriate anthelmintics available to their dogs.

Advanced approaches for the diagnosis and chemoprevention of canine vector-borne pathogens and parasites-Implications for the Asia-Pacific region and beyond

Vector-borne pathogens (VBPs) of canines are a diverse range of infectious agents, including viruses, bacteria, protozoa and multicellular parasites, that are pernicious and potentially lethal to their hosts. Dogs across the globe are afflicted by canine VBPs, but the range of different ectoparasites and the VBPs that they transmit predominate in tropical regions. Countries within the Asia-Pacific have had limited prior research dedicated to exploring the epidemiology of canine VBPs, whilst the few studies that have been conducted show VBP prevalence to be high, with significant impacts on dog health. Moreover, such impacts are not restricted to dogs, as some canine VBPs are zoonotic. We reviewed the status of canine VBPs in the Asia-Pacific, with particular focus on nations in the tropics, whilst also investigating the history of VBP diagnosis and examining recent progress in the field, including advanced molecular methods, such as next-generation sequencing (NGS). These tools are rapidly changing the way parasites are detected and discovered, demonstrating a sensitivity equal to, or exceeding that of, conventional molecular diagnostics. We also provide a background to the armoury of chemopreventive products available for protecting dogs from VBP. Here, field-based research within high VBP pressure environments has underscored the importance of ectoparasiticide mode of action on their overall efficacy. The future of canine VBP diagnosis and prevention at a global level is also explored, highlighting how evolving portable sequencing technologies may permit diagnosis at point-of-care, whilst further research into chemopreventives will be essential if VBP transmission is to be effectively controlled.

Prevalence of hookworm infections among stray dogs and molecular identification of hookworm species for the first time in Bangladesh

Hookworms are the most common and voracious blood-sucking parasites of the small intestines of mammalian hosts such as dogs, cats, ruminants and humans. Canine hookworms are endemic in the Southeast Asian countries including Bangladesh. There is scarcity of information on the prevalence of hookworms of stray dogs in Bangladesh. The present study determined the prevalence of canine hookworms using fecal examination followed by morphometric and molecular identification. Fecal samples were collected from 320 stray dogs living in rural areas of Mymensingh district (Gauripur upazila, Mymensingh sadar upazila and Tarakanda upazila) and hookworm eggs were identified using the flotation techniques. The overall prevalence of hookworm was 79.1% through microscopic examination. Estimated fecal prevalence was higher in Gauripur upazila (89.7%) followed by Mymensingh sadar upazila (84.8%) and Tarakanda upazila (53.2%). Five hookworm species were identified based on the morphometric examination, namely, Ancylostoma caninum, Ancylostoma ceylanicum, Ancylostoma tubaeforme, Ancylostoma braziliense and Ancylostoma duodenale, respectively. Polymerase Chain Reaction (PCR) was performed with the genomic DNA by targeting the 5.8S rRNA (~ 404 bp) and Cytochrome oxidase-1 (Cox 1, ~ 450 bp) and confirmed the identification for the first time in Bangladesh. This study reveals that stray dogs may act as reservoir hosts of human hookworm infection. Further detail molecular study is warranted to explore the genetic diversity of hookworms that infect both dogs and human in Bangladesh.

Zoonotic hookworms of dogs and cats - lessons from the past to inform current knowledge and future directions of research

The early-to-mid 1900s was an era that marked the first published reports of clinical cases and experimental human infections that provided valuable evidence to inform our current knowledge on the zoonotic nature of the canid and felid hookworms. To this day, descriptions of the pathognomonic syndromes produced in humans by these early pioneers provide vital information on the putative geographical distribution of these hookworm species, even before their discovery in dogs and cats. Cases of hookworm-related cutaneous larvae migrans and Ancylostoma caninum-induced eosinophilic enteritis continue to be reported in the medical literature, most commonly in recent migrants or returned travellers who have spent time in regions in which these canine and feline hookworms remain highly endemic. Ancylostoma ceylanicum, now recognised as the second most common hookworm infecting humans in the Asia Pacific region, is also being reported in regions of Africa and South America previously assumed free of this parasite. Despite the substantial technological progress made in the field of parasite diagnostics, our knowledge on the epidemiology and population-level morbidity impacts of these zoonotic hookworms in humans has remained relatively stagnant over the last few decades, with 'covert' infections continuing to remain undetected by currently available forms of routine diagnostics. Improved diagnostic tools that enable accurate and rapid species-specific diagnosis of zoonotic hookworm infections in humans are required to provide the necessary evidence to advocate for future investments in One Health-based intervention strategies.

Prevalence and risk factors of Taenia hydatigena in dogs, pigs, and cattle in the Central Highlands of Vietnam

Taenia hydatigena is a globally distributed canine tapeworm. The canine tapeworm results in economic impacts for farmers owing to organ condemnation. T. hydatigena utilizes dogs and other carnivores as definitive hosts while swine and ruminants serve as intermediate hosts. T. hydatigena is endemic in Vietnam; however, information on the prevalence and risk factors associated with infection is scarce. This cross-sectional study aims to identify the prevalence of T. hydatigena taeniasis in dogs and T. hydatigena cysticercosis in pigs and cattle. The risk factors associated with taeniasis in dogs were identified using a fixed effects logistic regression model and quantified using population attributable fractions. The prevalence of T. hydatigena taeniasis in dogs and T. hydatigena cysticercosis in pigs and cattle was 10.31% (95% CI 8.21 to 12.84%), 7.60% (95% CI 6.34 to 9.08%), and 11.11% (95% CI 7.63 to 11.81%), respectively; these levels were lower than those reported in other regions of Vietnam. The population attributable fraction of risk factors associated with T. hydatigena taeniasis in dogs for dogs living in proximity of an abattoir, those having access to raw pork or beef viscera, and those living in multi-dog households were 80%, 19%, and 7%, respectively. This current study identified and quantified the risk factors for taeniasis in dogs thus advocating for targeted community intervention programs to break the lifecycle of T. hydatigena in Dak Lak province.

Molecular characterization of Cysticercus tenuicollis isolates from sheep in the Nile Delta, Egypt and a review on Taenia hydatigena infections worldwide

The predator–prey-transmitted cestode Taenia hydatigena infects a wide range of definitive and intermediate hosts all over the world. Domestic and sylvatic cycles of transmission are considered as well. The parasite has considerable economic importance, particularly in sheep. Here, the molecular characters of T. hydatigena cysticerci in sheep from the Nile Delta, Egypt were investigated for the first time. For this purpose, 200 sheep carcasses and their offal were inspected at the municipal abattoir, Dakahlia governorate, Egypt. Cysticerci of T. hydatigena were collected and molecularly characterized employing the mitochondrial 12S rRNA gene. Cysticerci were found in 42 (21%) sheep, mostly attached to the omenti, mesenteries and livers. After molecular confirmation, nine isolates were sequenced displaying six different haplotypes. Analysis of the T. hydatigena 12S rRNA nucleotide sequences deposited in GenBank revealed 55 haplotypes out of 69 isolates, displaying high haplotype (0.797) and low nucleotide (0.00739) diversities. For the Tajima D neutrality index, a negative value (−2.702) was determined, indicating the population expansion of the parasite. Additionally, global data summarized in this study should be useful to set up effective control strategies against this ubiquitous parasite.

Dipylidium caninum Infection in Dogs and Humans in Bishoftu Town, Ethiopia

Dogs are reservoirs of many zoonotic diseases. In Ethiopia, the majority of owned dogs are semi-stray, freely roaming in the community. Studies reporting dog borne zoonotic diseases are scarce in Ethiopia. This study was conducted to assess Dipylidium caninum infection in dogs and in children with gastrointestinal complaints in Bishoftu Town, Oromia. We collected 384 fecal samples from dogs presented to veterinary teaching hospital and 259 stool samples from children presented to Bishoftu Hospital for clinical examination. Samples were first macroscopically examined for the presence of proglotids, followed by microscopic examination for the presence of eggs with the direct smear following flotation technique. The prevalence of D. caninum was 21% (95% CI: 16.6-24.9) in dogs. Although not statistically significant (p > 0.05), higher prevalence was detected in adult (11.9%), local breed (17.7%), and male (12.6%) dogs compared to young (8.59%), exotic breed (2.86%), and females (7.81%), respectively. Dipylidium caninum was detected in a stool sample obtained from a three year-old child (0.4%, 1/259). This study showed that the prevalence of D. caninum in the dogs is high while it is rare in children. Although the prevalence in children is negligible in this study, the high proportion of infected dogs can pose a significant risk of infection in the general human population. Public health risk can be reduced by eliminating the semi-roaming of owned dogs and proper management of dogs with regular deworming and prevention of environmental contamination with dog feces. Similarly, raising public awareness about dog borne zoonoses and avoiding contact with dog feces are important.

Evolutionary ecology of Lyme Borrelia

The bacterial genus, Borrelia, is comprised of vector-borne spirochete species that infect and are transmitted from multiple host species. Some Borrelia species cause highly-prevalent diseases in humans and domestic animals. Evolutionary, ecological, and molecular research on many Borrelia species have resulted in tremendous progress toward understanding the biology and natural history of these species. Yet, many outstanding questions, such as how Borrelia populations will be impacted by climate and land-use change, will require an interdisciplinary approach. The evolutionary ecology research framework incorporates theory and data from evolutionary, ecological, and molecular studies while overcoming common assumptions within each field that can hinder integration across these disciplines. Evolutionary ecology offers a framework to evaluate the ecological consequences of evolved traits and to predict how present-day ecological processes may result in further evolutionary change. Studies of microbes with complex transmission cycles, like Borrelia, which interact with multiple vertebrate hosts and arthropod vectors, are poised to leverage the power of the evolutionary ecology framework to identify the molecular interactions involved in ecological processes that result in evolutionary change. Using existing data, we outline how evolutionary ecology theory can delineate how interactions with other species and the physical environment create selective forces or impact migration of Borrelia populations and result in micro-evolutionary changes. We further discuss the ecological and molecular consequences of those micro-evolutionary changes. While many of the currently outstanding questions will necessitate new experimental designs and additional empirical data, many others can be addressed immediately by integrating existing molecular and ecological data within an evolutionary ecology framework.

Assessing risk factors associated with prevalence of canine gastrointestinal parasitic zoonoses in Andhra Pradesh, India

Prevalence and risk factors associated with gastrointestinal parasites in dogs from central coastal districts of Andhra Pradesh, India was estimated by coprological examination. On examination of faecal samples of 1,907 dogs by saturated zinc sulphate floatation, sedimentation technique and modified Ziehl-Nielsen staining, an overall prevalence of 52.2% was observed. Single species infections were more common (49.7%) than mixed infections (2.5%). A total of 11 different species were detected. The most prevalent species was Ancylostoma canis followed by Toxocara canis, Cystoisospora ohioensis, Dipylidium caninum, Toxascaris leonina, Capillaria aerophila, Diphyllobothrium latum, Cystoisospora canis, Entamoeba spp., Trichuris vulpis and Cryptosporidium spp. The overall prevalence was high in stray dogs (65.9%). The prevalence of A. caninum (31.6%) was significant in pet dogs. Significant relationship between the season and prevalence of parasites was observed, the infection being more prevalent during rainy season. Binary logistic regression analysis identified age, season and the living condition of dogs and lack of zoonotic awareness of owners as risk factors for different parasitic infection.

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.

Canine vector-borne pathogens from dogs and ticks from Tamil Nadu, India

Canine vector-borne diseases (CVBDs) pose a major health problem in dogs globally, with the potential to cause zoonoses, in particular in developing countries where scientific knowledge on the topic is minimal. Blood samples and ticks were collected from stray dogs in Tamil Nadu, South India to assess the prevalence of CVBD-causing pathogens (Anaplasma spp., Babesia spp., Ehrlichia spp., Hepatozoon spp., filarioids and Leishmania spp.). Of the 230 dogs examined, 229 (99.6%) were infested by ticks (mean intensity, 5.65) with Rhipicephalus sanguineus sensu lato and Rhipicephalus haemaphysaloides being morphologically identified in the 98.3% and 1.7% of the infested dogs, respectively. Overall, the 67.8% (n = 156) of dogs was positive for at least one pathogen with Hepatozoon canis being the most prevalent (37.8%) followed by Anaplasma platys (22.6%), Ehrlichia canis (16.1%) Babesia vogeli (10%), Anaplasma phagocytophilum (0.4%) and Babesia gibsoni (0.4%). Two filarioids (Dirofilaria sp. "hongkongensis" and Brugia malayi, 0.4%) were diagnosed in sampled animals. Co-infection with H. canis and A. platys was the most prevalent (8.3%, P = 0.00001), whilst all animals scored negative for Leishmania spp.. Out of 295 ticks analysed, 215 R. sanguineus s.l. (75.4%) and 8 R. haemaphysaloides (88.9%) were positive for at least one pathogen with H. canis as the predominant species (42.5%), followed by A. platys (33.8%), E. canis (16.9%), B. vogeli (3.8%) and A. phagocytophilum (0.3%). Fifty-six dogs (35.9%) harboured the same pathogen as the respective tick specimens, while 29 dogs (18.6%) had a different pathogen. Thirteen sequence types (STs) were identified for H. canis, with ST2 (49.4%) as the most representative in dogs and ST1 (73.5%) in ticks. Similarly, seven STs were found for Anaplasma spp. (i.e., five for A. platys, one for A. phagocytophilum and one for Anaplasma sp.), with ST2 as the most representative in dogs (70.6%) and ST3 (52.5%) in ticks for A. platys. Only one ST was identified for B. vogeli, B. gibsoni, E. canis, D. sp. "hongkongensis" and B. malayi. Regular surveillance and adoption of adequate treatment and control measures are needed to reduce the risk of disease-causing pathogens in stray dogs and of pathogens with zoonotic potential.

Canine Toxocariosis: Its prevalence, incidence and occurrence in the Indian subcontinent

Toxocariosis is an important neglected tropical helminth disease of zoonotic significance for which canids are the definitive hosts. Dogs are also considered the sentinel host for the occurrence of T. canis infections in humans. Therefore, understanding its prevalence in canine population is imperative for any effective disease control in humans. A comprehensive review of literature on the prevalence of T. canis in canids was lacking from the Indian subcontinent which necessitated our efforts to compile available data published on this topic. Data on prevalence, incidence and occurrence of this helminths in canids were presented in this review as tabular format for easy comprehension. Moreover, the data were categorized based on the region where the studies were conducted with an aim to understand the spatial distribution of this parasite in the subcontinent. Factors influencing the regional prevalence/occurrence of T. canis such as type of canids (stray or pet), age, sex, breed, season and the choice of analytical methods were also discussed. In addition, data on the prevalence of T. canis in environmental samples and in zoo canids were also compiled and presented. We anticipate such an exhaustive review of literature available mostly in the journals published from the subcontinent would become a point source of information necessary for prioritizing future surveillance efforts in this region and for making informed policy decision to control this zoonotic helminth infection.

Not just a walk in the park: Occurrence of intestinal parasites in dogs roaming recreational parks in Chandigarh, Northern India

Chandigarh, a city in North-west India, has numerous parks and recreational areas where stray dogs roam freely and pet dogs are exercised. This allows for extensive human-dog interaction, which may pose a public health threat. The aim of this study was to determine the occurrence of gastrointestinal parasites of public health importance, and their seasonal variation, in canine faecal samples obtained from recreational parks in Chandigarh. A total of 212 samples were collected from 10 parks during the winter (January 2015; N = 107) and monsoon season (September 2015; N = 105), to assess the prevalence of intestinal zoonotic parasites and any seasonal variations. The samples were analysed for helminth eggs using McMaster counting chambers. Immunofluorescent antibody testing was used to analyse samples for Cryptosporidium oocysts and Giardia cysts. The Giardia-positive samples were genotyped by conventional multi-locus PCR to determine their assemblage and zoonotic potential. Among the 212 samples, strongyle-type eggs were found in 34 (16.0%), Toxocara spp. eggs were found in 6 (2.8%), taeniid eggs in 1 (0.5%), Cryptosporidium spp. oocysts in 4 (1.9%) and Giardia duodenalis cysts in 49 (23.1%). Trichuris eggs were not detected. The majority of the successfully amplified Giardia isolates belonged to canid-specific assemblages. The prevalence of Giardia cysts in faecal samples was significantly higher during winter than in the monsoon season, whereas helminth-egg prevalence unaffected by season. The prevalence of strongyle-type eggs and Giardia cysts in dog faeces was lower in more affluent areas of the city than those of less affluence. There was no significant difference in the intensity of infection between the seasons. The results indicate that faeces from dogs contaminating parks in Chandigarh do not usually contain parasite transmission stages that pose a significant risk to human health. However, the importance of minimising contamination of public parks with dog faeces is highlighted.

Ancylostoma ceylanicum, novel etiological agent for traveler's diarrhea-report of four Japanese patients who returned from Southeast Asia and Papua New Guinea

Background

Countries in the Southeast Asia region have a high prevalence of soil-transmitted helminth, such as roundworm, whipworm, and hookworms [Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum]. Recent molecular-based surveys have revealed that A. ceylanicum, a zoonotic hookworm, is likely the second most prevalent hookworm species infecting humans in that part of the world, while others have noted that this infection is an emerging public health risk not only for indigenous people but also for visitors from other countries.

Case presentation

We recently encountered four cases of A. ceylanicum infection in Japanese individuals who returned from Southeast Asia and Papua New Guinea. Case 1 was a 25-year-old male who stayed in a rainforest in Malaysia for 4 weeks, where he developed abdominal pain and diarrhea in the third week. Eleven adult worms (five males, six females) were expelled after treatment with pyrantel pamoate and identified as A. ceylanicum based on morphological characteristics and DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Case 2 was a 26-year-old male who spent 2 years as an overseas cooperation volunteer for agriculture in Papua New Guinea. He did not note any symptoms at that time, though eggs were detected in feces samples at a medical check-up examination after returning. Although collection of adult worms was unsuccessful, DNA analysis of the eggs for cox1 and the ribosomal internal transcribed spacer (ITS)-1 and ITS-2 genes demonstrated that they were A. ceylanicum. Case 3 was a 47-year-old male who spent 1 month in a rural village in Lao People's Democratic Republic and began suffering from watery diarrhea from the third week. A total of nine adult worms (three males, six females) were collected by endoscopic procedures and following treatment with pyrantel pamoate. Morphological examination and molecular analyses of the cox1 gene showed that they were A. ceylanicum. Case 4 was a 27-year-old male who participated in group travel to India for 5 days. Three weeks after returning, he developed abdominal pain and diarrhea. Hookworm eggs were found in feces samples and developed into larvae in culture, which were identified as A. ceylanicum based on molecular analysis of the cox1 gene. Eosinophilia was observed in all of the cases prior to treatment.

Conclusions

A. ceylanicum should be recognized as an important etiologic pathogen of hookworm diseases in travelers to countries in the Southeast Asia and West Pacific Ocean regions.

Probiotics for the Control of Helminth Zoonosis

This paper is a comprehensive, concise, and an up to date review about probiotics effect and mechanisms against helminth infections of zoonotic importance. Zoonoses are diseases that can be transmitted from animals to humans in a reversible way. Despite zoonotic helminth diseases being still a challenge to the public health and the agriculture industries globally, they were still neglected in both human and veterinary medicine. Moreover, the increasing emergence of anthelmintic drug resistance constitutes failures of most disease control strategies, alarming for a quest to new alternative control approaches. Consequently, the use of beneficial microorganisms, probiotics, is becoming interesting for its prophylactic or therapeutic application against several diseases including helminths. Recent studies on probiotics against parasites and the interactions between bacteria, parasites, and the immune system in the gut draw much attention. However, the effects of these beneficial microorganisms in helminth infections remain largely unexplored. Therefore, the aim of the present review is to raise attention and to summarize recent findings on probiotics research against helminth parasites of zoonotic significance. State-of-the-art research on beneficial effects of bacteria on helminth infections and their proposed mechanisms of action is thoroughly discussed.

Soil-Transmitted Helminths in Tropical Australia and Asia

Soil-transmitted helminths (STH) infect 2 billion people worldwide including significant numbers in South-East Asia (SEA). In Australia, STH are of less concern; however, indigenous communities are endemic for STH, including Strongyloides stercoralis, as well as for serious clinical infections due to other helminths such as Toxocara spp. The zoonotic hookworm Ancylostoma ceylanicum is also present in Australia and SEA, and may contribute to human infections particularly among pet owners. High human immigration rates to Australia from SEA, which is highly endemic for STH Strongyloides and Toxocara, has resulted in a high prevalence of these helminthic infections in immigrant communities, particularly since such individuals are not screened for worm infections upon entry. In this review, we consider the current state of STH infections in Australia and SEA.

Dogs' Gastrointestinal Parasites and their Association with Public Health in Iran

INTRODUCTION

Dogs harbour zoonotic parasites that cause serious infections in humans, such as visceral larva migrans, ocular larva migrans, cystic echinococcosis, and alveolar echinococcosis. Studies on dogs' gastrointestinal parasites in different geographical locations are required to increase knowledge of the risk of canine zoonoses in human populations.

MATERIAL AND METHODS

The presence of parasites was examined in 450 faecal samples collected from eight zones of Zanjan province, northwest Iran from June to November 2015. The samples were examined using the sedimentation concentration method and modified Ziehl-Neelsen staining.

RESULTS

Gastrointestinal parasites were found in 86 (19.1%) faecal samples. Sarcocystis spp. (7.3%), Taenia/Echinococcus spp. (5.6%), Toxocara spp. (1.8%), and Cystoisospora spp. (1.6%) were the most common parasites observed. The other detected parasites consisted of Dicrocoelium dendriticum (0.7%), Eimeria spp. (0.7%), Cryptosporidium spp. (0.4%), Physaloptera spp. (0.4%), Giardia spp. (1.3%), and Spirocerca lupi (1.3%). The lowest parasite infection rates belonged to Trichuris vulpis and Acanthocephalans (0.2% each).

CONCLUSION

This study provides current information on the infection rates in dog populations in Zanjan Province. Furthermore, the study shows a high prevalence of gastrointestinal parasitic infections, including zoonotic ones and particularly Taenia/Echinococcus spp., potentially transmissible to humans and thus relevant to public health.

Molecular identification of Sarcocystis species in raw hamburgers using PCR-RFLP method in Kashan, central Iran

The prevalence of bovine Sarcocystosis is high in the most regions of the world. It can be a human health problem due to consumption of raw or under cooked hamburgers or other bovine meat products. This study was carried out to investigate the prevalence and species identification of Sarcocystis among of hamburgers, using PCR-RFLP methods in Kashan, central Iran. Overall 200 raw industrial hamburgers samples with at least 60% meat were randomly collected from nine different brands in Kashan, central Iran. The genomic DNA was extracted and a PCR-RFLP method was used to amplify an approximately 900 bp fragment at the 18S rRNA(SSU) gene, restriction enzyme BclI was used for species identification. The results showed that 58 (29%) of 200 tested hamburger samples were infected to Sarcocystis spp. The prevalence rate was 31.25 and 26.9% in the hamburgers with 90 and 60-75% meat, respectively. According to PCR-RFLP analysis, 43 (74.1%) of the 58 isolates were Sarcocystis cruzi, 12 (20.7%) showed co-infection to S. cruzi and Sarcocystis hirsuta, 2 (3.5%) was mixed infected to S. cruzi and Sarcocystis hominis, 1 (1.7%) showed the pattern of mix infection to three species. This study revealed one-third of industrial hamburger were infected to S. cruzi or mixed infection of S. cruzi with other bovine sarcocytosis. To prevent cattle infection, the possible ingestion of the disposal sporocyst stage from dogs must be eliminated. Although in this study, the prevalence of S. hominis was low and cannot be considered as a major zoonosis, it should be recommended avoiding eating under cooked hamburger and other bovine meat products to prevent human infection.

Prevalence of gastrointestinal helminth parasites of zoonotic significance in dogs and cats in lower Northern Thailand

Gastrointestinal zoonotic helminths of dogs and cats have a public health concern worldwide. We investigated the prevalence of gastrointestinal helminths of zoonotic significance in dogs and cats in lower Northern Thailand and utilized molecular tools for species identification of hookworms and Opisthorchis viverrini. Fecal samples of 197 dogs and 180 cats were collected. Overall prevalence of infection using microscopy was 40.1% in dogs and 33.9% in cats. Helminth infection found in both dogs and cats included hookworms, Spirometra spp., Taenia spp., Toxocara spp., O. viverrini, Strongyloides spp. and Trichuris spp. Hookworms were the most common helminth in dogs, while Spirometra spp. were the most prevalent in cats. Among hookworm infection in dogs and cats, Ancylostoma ceylanicum was the most prevalent hookworm, being 82.1% in hookworm infected dogs and 95.8% in hookworm infected cats. Mixed-infection due to hookworms and Spirometra spp. was the most dominant in both dogs and cats. Our finding showed that zoonotic helminth infection is highly prevalent in dogs and cats in the lower Northern area of Thailand.

Molecular Identification of Hookworm Isolates in Humans, Dogs and Soil in a Tribal Area in Tamil Nadu, India

Background

Hookworms (Necator americanus and Ancylostoma duodenale) remain a major public health problem worldwide. Infections with hookworms (e.g., A. caninum, A. ceylanicum and A. braziliense) are also prevalent in dogs, but the role of dogs as a reservoir for zoonotic hookworm infections in humans needs to be further explored.

Methodology/Principal Findings

As part of an open-label community based cluster-randomized trial in a tribal area in Tamil Nadu (India; 2013–2015), a total of 143 isolates of hookworm eggs from human stool were speciated based on a previously described PCR-RFLP methodology. The presence of hookworm DNA was confirmed in 119 of 143 human samples. N. americanus (100%) was the most prevalent species, followed by A. caninum (16.8%) and A. duodenale (8.4%). Because of the high prevalence of A. caninum in humans, dog samples were also collected to assess the prevalence of A. caninum in dogs. In 68 out of 77 canine stool samples the presence of hookworms was confirmed using PCR-RFLP. In dogs, both A. caninum (76.4%) and A. ceylanicum (27.9%) were identified. Additionally, to determine the contamination of soil with zoonotic hookworm larvae, topsoil was collected from defecating areas. Hookworm DNA was detected in 72 out of 78 soil samples that revealed presence of hookworm-like nematode larvae. In soil, different hookworm species were identified, with animal hookworms being more prevalent (A. ceylanicum: 60.2%, A. caninum: 29.4%, A. duodenale: 16.6%, N. americanus: 1.4%, A. braziliense: 1.4%).

Conclusions/Significance

In our study we regularly detected the presence of A. caninum DNA in the stool of humans. Whether this is the result of infection is currently unknown but it does warrant a closer look at dogs as a potential reservoir.

Hookworm infections remain a major public health problem in both tropical and subtropical parts of the world. To control the disease burden attributable to hookworms, large-scale deworming programs, in which drugs are administered to schoolchildren regardless of their infection status, are currently being implemented in endemic regions. However, these programs face some difficulties. One of them is the uncertainty about the role of animals in the transmission of hookworm infections. It is commonly believed that human-specific hookworms cause these infections, but there is growing evidence that the role of some animal-specific hookworms as cause of infection in humans should not be underestimated. We determined the different hookworms in humans, dogs and soil (eggs excreted by adult hookworms in stool are non-infectious, and need to develop and hatch on the soil before larvae can transmit disease by penetrating the skin) in a tribal area in India. In this area, the transmission of hookworms between humans and dogs is possible. Our results highlight the presence of DNA from animal-specific hookworms in both soil and human stool. Although these findings suggest that these animals could act as reservoir for zoonotic hookworm infections in humans, they should be interpreted with caution. This is because we lack the evidence to confirm A. caninum infections in our study population. Other potential reasons for the presence of DNA in stool are contamination of stool with environmental eggs or larvae during sample collection and passive passage in which eggs or larvae are ingested but did result in any infection.

A field survey on parasites and antibodies against selected pathogens in owned dogs in Lilongwe, Malawi

The aim of this study was to screen for selected parasites and antibody levels against vectorborne pathogens in owned dogs in Lilongwe, Malawi. The study population consisted of 100 dogs; 80 participating in vaccination-spaying campaigns and 20 visiting a veterinary clinic as paying clients. All dogs went through a general physical examination including visual examination for signs of ectoparasites. A total of 100 blood samples were analysed using commercial snap tests and 40 faecal samples by egg flotation in saturated sodium chloride. The sampled dogs had a seroprevalence of 12% for Anaplasma spp., 22% for Ehrlichia spp., 4% for Dirofilaria immitis and 1% for Leishmania spp. Eggs from Ancylostoma spp. were found in 80% of the faecal samples, whereas eggs of Trichuris vulpis, Toxocara canis and Toxascaris leonina were only present in 3%, 8% and 13% of the samples, respectively. Ectoparasites such as Ctenocephalides sp., Trichodectes sp. and ticks were present on 98%, 25% and 11%, respectively, of the campaign dogs. Among client dogs, 35% had Ctenocephalides fleas, 10% had Trichodectes lice and none had ticks. Public education and prophylactic treatment could be used to improve the animal welfare of dogs; this would most likely also have positive impact on public health.

Efficacy of afoxolaner plus milbemycin oxime chewable tablets against naturally acquired intestinal nematodes in dogs

The efficacy of oral afoxolaner plus milbemycin oxime combination chewable tablets (NexGard Spectra, Merial) against naturally acquired intestinal nematode infections in dogs was evaluated in six negative control, blinded studies including a total of 114 dogs. Dogs were selected based on a pre-treatment fecal examination indicating patent infections with hookworms (two studies), Toxocara or Toxascaris ascarids (one study each) or Trichuris whipworms (two studies). In each study, dogs were assigned to blocks of two animals each, based on decreasing pre-treatment body weight and were randomly allocated to one of two groups consisting of eight, nine or 10 dogs: untreated (control) or treated with the combination chewable tablet formulation. Chewable tablets were combined to provide doses of actives as close as possible to the minimum effective dose of afoxolaner and milbemycin oxime, i.e., 2.5 mg/kg body weight and 0.5 mg/kg body weight, respectively, once on Day 0. For parasite recovery and count, dogs were euthanized humanely and necropsied seven or eight days after treatment. A single treatment with afoxolaner plus milbemycin oxime chewable tablets provided 94.8% and 90.9% efficacy against adult Ancylostoma braziliense and A. caninum, respectively, 97.8% and 99.4% efficacy against adult Toxocara canis and Toxascaris leonina, respectively, and ≥98.3% efficacy against adult Trichuris vulpis. Compared to untreated controls, nematode counts of the treated dogs were significantly reduced (F-test; p<0.002). In addition, analysis of the pooled data across studies revealed that treatment with afoxolaner plus milbemycin oxime chewable tablets reduced adult Uncinaria stenocephala burdens by 74.9% (p=0.002). All dogs tolerated the treatment well based on clinical observations post-treatment and daily clinical observations. No adverse experiences or other clinical problems related to the treatment were observed throughout the studies. The results of this series of controlled studies demonstrated high efficacy and excellent acceptability and safety of the afoxolaner plus milbemycin oxime chewable tablets when administered for treatment of a broad range of canine intestinal nematode infections.

Detection of Helminth Eggs and Identification of Hookworm Species in Stray Cats, Dogs and Soil from Klang Valley, Malaysia

The present study was conducted to determine the prevalence of helminth eggs excreted in the faeces of stray cats, dogs and in soil samples. A total of 505 fresh samples of faeces (from 227 dogs and 152 cats) and soil were collected. The egg stage was detected via microscopy after the application of formalin–ether concentration technique. Genomic DNA was extracted from the samples containing hookworm eggs and used for further identification to the species level using real-time polymerase chain reaction coupled with high resolution melting analysis. Microscopic observation showed that the overall prevalence of helminth eggs among stray cats and dogs was 75.7% (95% CI = 71.2%–79.9%), in which 87.7% of dogs and 57.9% of cats were infected with at least one parasite genus. Five genera of heliminth eggs were detected in the faecal samples, including hookworms (46.4%), Toxocara (11.1%), Trichuris (8.4%), Spirometra (7.4%) and Ascaris (2.4%). The prevalence of helminth infections among stray dogs was significantly higher than that among stray cats (p < 0.001). Only three genera of helminths were detected in soil samples with the prevalence of 23% (95% CI = 15.1%–31%), consisting of hookworms (16.6%), Ascaris (4%) and Toxocara (2.4%). The molecular identification of hookworm species revealed that Ancylostoma ceylanicum was dominant in both faecal and soil samples. The dog hookworm, Ancylostoma caninum, was also detected among cats, which is the first such occurrence reported in Malaysia till date. This finding indicated that there was a cross-infection of A. caninum between stray cats and dogs because of their coexistent within human communities. Taken together, these data suggest the potential role of stray cats and dogs as being the main sources of environmental contamination as well as for human infections.

Path analyses of cross-sectional and longitudinal data suggest that variability in natural communities of blood-associated parasites is derived from host characteristics and not interspecific interactions

BACKGROUND

The parasite composition of wild host individuals often impacts their behavior and physiology, and the transmission dynamics of pathogenic species thereby determines disease risk in natural communities. Yet, the determinants of parasite composition in natural communities are still obscure. In particular, three fundamental questions remain open: (1) what are the relative roles of host and environmental characteristics compared with direct interactions between parasites in determining the community composition of parasites? (2) do these determinants affect parasites belonging to the same guild and those belonging to different guilds in similar manners? and (3) can cross-sectional and longitudinal analyses work interchangeably in detecting community determinants? Our study was designed to answer these three questions in a natural community of rodents and their fleas, ticks, and two vector-borne bacteria.

METHODS

We sampled a natural population of Gerbillus andersoni rodents and their blood-associated parasites on two occasions. By combining path analysis and model selection approaches, we then explored multiple direct and indirect paths that connect (i) the environmental and host-related characteristics to the infection probability of a host by each of the four parasite species, and (ii) the infection probabilities of the four species by each other.

RESULTS

Our results suggest that the majority of paths shaping the blood-associated communities are indirect, mostly determined by host characteristics and not by interspecific interactions or environmental conditions. The exact effects of host characteristics on infection probability by a given parasite depend on its life history and on the method of sampling, in which the cross-sectional and longitudinal methods are complementary.

CONCLUSIONS

Despite the awareness of the need of ecological investigations into natural host-vector-parasite communities in light of the emergence and re-emergence of vector-borne diseases, we lack sampling methods that are both practical and reliable. Here we illustrated how comprehensive patterns can be revealed from observational data by applying path analysis and model selection approaches and combining cross-sectional and longitudinal analyses. By employing this combined approach on blood-associated parasites, we were able to distinguish between direct and indirect effects and to predict the causal relationships between host-related characteristics and the parasite composition over time and space. We concluded that direct interactions within the community play only a minor role in determining community composition relative to host characteristics and the life history of the community members.

Toward the formation of a Companion Animal Parasite Council for the Tropics (CAPCT)

This letter advises the imminent formation of the Companion Animal Parasites Council for the Tropics (CAPCT). The CAPCT consists of region-specific (e.g., Asia-Pacific, Latin America and Caribbean, Africa) experts comprising academics, veterinarians, parasitologists, physicians and allied industry partners that will work together to inform, guide and develop best-practice recommendations for the optimal diagnosis, treatment and control of companion animal parasites in the tropics, with the aim of protecting the health of pets and that of the public.