Parasites or cohabitants: cruel omnipresent usurpers or creative "éminences grises"?

Ancylostoma ceylanicum Infection in a Miniature Schnauzer Dog Breed

PURPOSE

Canine hookworm disease is a global zoonotic parasitic disease caused by a variety of nematodes in families Ancylostomatidae, including Ancylostoma spp., Necator spp., and Uncinaria spp., in the small intestine (mainly the duodenum) of dogs. The disease is widely distributed in China. The purpose of this study is to systematically diagnose and treat canine hookworm disease through the case of miniaturization Schnauzer dog feed infected with A. ceylanicum, so as to provide experimental basis for subsequent prevention and control of canine hookworm disease.

METHODS

In the current study, we isolated hookworm eggs from a diseased miniature schnauzer, then the polymerase chain reaction (PCR) was used to amplify the ITS1-5.8S-ITS2 gene sequence from genomic DNA extracted from hookworms. Phylogenetic analysis based on ITS1-5.8S-ITS2 gene sequence sequences was inferred using MEGA-X. After phylogenetic analysis, etiologic and symptomatic therapies were used to treat the canine hookworm disease.

RESULTS

The sequencing results showed that the length of the ITS1-5.8S-ITS2 gene sequence was approximately 960 bp, and ITS1 and ITS2 were extracted to analyze similarity with other hookworms to build a phylogenetic tree. After phylogenetic analysis, the results showed that the diseased miniature schnauzer was infected by A. ceylanicum. Using etiologic and symptomatic therapies, the sick dog with an A. ceylanicum infection was also treated for 5 days.

CONCLUSIONS

To our knowledge, this is the first report of diagnosis and treatment for canine hookworm disease in Guangzhou city. In addition, with the improvement of economic level, the scale of pet dog breeding is also increasing. The diagnostic methods and treatment schemes adopted in this report will help to standardize the prevention and control of canine hookworm disease.

A Devil of a Transmissible Cancer

Devil facial tumor disease (DFTD) encompasses two independent transmissible cancers that have killed the majority of Tasmanian devils. The cancer cells are derived from Schwann cells and are spread between devils during biting, a common behavior during the mating season. The Centers for Disease Control and Prevention (CDC) defines a parasite as "An organism that lives on or in a host organism and gets its food from, or at, the expense of its host." Most cancers, including DFTD, live within a host organism and derive resources from its host, and consequently have parasitic-like features. Devil facial tumor disease is a transmissible cancer and, therefore, DFTD shares one additional feature common to most parasites. Through direct contact between devils, DFTD has spread throughout the devil population. However, unlike many parasites, the DFTD cancer cells have a simple lifecycle and do not have either independent, vector-borne, or quiescent phases. To facilitate a description of devil facial tumor disease, this review uses life cycles of parasites as an analogy.

Free-ranging dogs prefer petting over food in repeated interactions with unfamiliar humans

Dogs (Canis lupus familiaris) are the first species to have been domesticated and, unlike other domesticated species, they have developed a special bond with their owners. The ability to respond to human gestures and language, and the hypersocial behaviours of dogs are considered key factors that have led them to become man's best friend. Free-ranging dogs provide an excellent model system for understanding the dog-human relationship in various social contexts. In India, free-ranging dogs occur in all possible human habitations. They scavenge among garbage, beg for food from humans, give birth in dens close to human habitations, and establish social bonds with people. However, there is ample dog-human conflict on the streets, leading to morbidity and mortality of dogs. Hence, the ability to assess an unfamiliar human before establishing physical contact could be adaptive for dogs, especially in the urban environment. We tested a total of 103 adult dogs to investigate their response to immediate social and long-term food and social rewards. The dogs were provided a choice of obtaining food either from an experimenter's hand or the ground. The dogs avoided making physical contact with the unfamiliar human. While immediate social reward was not effective in changing this response, the long-term test showed a strong effect of social contact. Our results revealed that these dogs tend to build trust based on affection, not food. This study provides significant insights into the dynamics of dog-human interactions on the streets and subsequent changes in behaviour of dogs through the process of learning.

Can Mixed Parasite Infections Thwart Targeted Malaria Elimination Program in India?

India is highly endemic to malaria with prevalence of all five species of human malaria parasites of Plasmodium genus. India is set for malaria elimination by 2030. Since cases of mixed Plasmodium species infections remain usually undetected but cause huge disease burden, in order to understand the distributional prevalence of both monospecies infections and mixed species infections in India, we collated published data on the differential infection incidences of the five different malaria parasites based on PCR diagnostic assay. About 11% of total cases were due to mixed species infection. Among several interesting observations on both single and mixed parasitic infections, incidences of Plasmodium falciparum monoinfection were found to be significantly higher than P. vivax monoinfection. Also, P. malariae seems to be emerging as a potential malaria threat in India. Putting all the facts together, it appears that the dream of achieving malaria elimination in India will not be completely successful without dealing with mixed species infection.

Health and epidemiological approaches of Trypanosoma evansi and equine infectious anemia virus in naturally infected horses at southern Pantanal

Equine infectious anemia virus (EIAV) and Trypanossoma evansi are endemic in Brazilian Pantanal Biome, an important area for livestock production. In this sense, we evaluated the epidemiological single and co-infection effects of T. evansi and EIAV in naturally infected horses in the southern Pantanal wetland by serological tests and hematological assays. Both higher seroprevalence and heath poor condition of the sampled animals were associated with differences in horse management between farms. We found that the negative animals for both infectious agents (NN) represented the major group in F1 (37%), and the smallest group in F2 (19%). Furthermore, we recorded higher EIAV seroprevalence (56%) in F2, compared to F1 (38%). We observed that T. evansi infection was mostly related to young horses, as seen by their higher seroprevalence, ranging from 70.7% in the beginning of the rainy season to 81% in the end of flood period, in comparison with the values of 42% and 68%, respectively, in working animals. on the other hand, working animals showed a higher seroprevalence for EIAV (48%) in both seasons than young horses. We observed that the management of working horses could be a risk factor of EIAV infection. On the other hand, as T. evansi is maintained in the study region by many species of wild mammals, the mechanical transmission through blood-sucking vectors ensures the infection to horses since early. Our results showed that single or co-infection by EIAV and T. evansi caused different degree of anemia in the infected animals. Moreover, the health of horses in Brazilian Pantanal is also influenced by differences in horse management and environmental circumstances.

The importance of multiparasitism: examining the consequences of co-infections for human and animal health

Most parasites co-occur with other parasites, although the importance of such multiparasitism has only recently been recognised. Co-infections may result when hosts are independently infected by different parasites at the same time or when interactions among parasite species facilitate co-occurrence. Such interactions can have important repercussions on human or animal health because they can alter host susceptibility, infection duration, transmission risks, and clinical symptoms. These interactions may be synergistic or antagonistic and thus produce diverse effects in infected humans and animals. Interactions among parasites strongly influence parasite dynamics and therefore play a major role in structuring parasite populations (both within and among hosts) as well as host populations. However, several methodological challenges remain when it comes to detecting parasite interactions. The goal of this review is to summarise current knowledge on the causes and consequences of multiparasitism and to discuss the different methods and tools that researchers have developed to study the factors that lead to multiparasitism. It also identifies new research directions to pursue.

Parasite-Parasite Interactions in the Wild: How To Detect Them?

Inter-specific interactions between parasites impact on parasite intra-host dynamics, host health, and disease management. Identifying and understanding interaction mechanisms in the wild is crucial for wildlife disease management. It is however complex because several scales are interlaced. Parasite-parasite interactions are likely to occur via mechanisms at the within-host level, but also at upper levels (host population and community). Furthermore, interactions occurring at one level of organization spread to upper levels through cascade effects. Even if cascade effects are important confounding factors, we argue that we can also benefit from them because upper scales often provide a way to survey a wider range of parasites at lower cost. New protocols and theoretical studies (especially across scales) are necessary to take advantage of this opportunity.

Selfishness, warfare, and economics; or integration, cooperation, and biology

The acceptance of Darwin's theory of evolution by natural selection is not complete and it has been pointed out its limitation to explain the complex processes that constitute the transformation of species. It is necessary to discuss the explaining power of the dominant paradigm. It is common that new discoveries bring about contradictions that are intended to be overcome by adjusting results to the dominant reductionist paradigm using all sorts of gradations and combinations that are admitted for each case. In addition to the discussion on the validity of natural selection, modern findings represent a challenge to the interpretation of the observations with the Darwinian view of competition and struggle for life as theoretical basis. New holistic interpretations are emerging related to the Net of Life, in which the interconnection of ecosystems constitutes a dynamic and self-regulating biosphere: viruses are recognized as a macroorganism with a huge collection of genes, most unknown that constitute the major planet's gene pool. They play a fundamental role in evolution since their sequences are capable of integrating into the genomes in an “infective” way and become an essential part of multicellular organisms. They have content with “biological sense” i.e., they appear as part of normal life processes and have a serious role as carrier elements of complex genetic information. Antibiotics are cell signals with main effects on general metabolism and transcription on bacterial cells and communities. The hologenome theory considers an organism and all of its associated symbiotic microbes (parasites, mutualists, synergists, amensalists) as a result of symbiopoiesis. Microbes, helmints, that are normally understood as parasites are cohabitants and they have cohabited with their host and drive the evolution and existence of the partners. Each organism is the result of integration of complex systems. The eukaryotic organism is the result of combination of bacterial, virus, and eukaryotic DNA and it is the result of the interaction of its own genome with the genome of its microbiota, and their metabolism are intertwined (as a “superorganism”) along evolution. The darwinian paradigm had its origin in the free market theories and concepts of Malthus and Spencer. Then, nature was explained on the basis of market theories moving away from an accurate explanation of natural phenomena. It is necessary to acknowledge the limitations of the dominant dogma. These new interpretations about biological processes, molecules, roles of viruses in nature, and microbial interactions are remarkable points to be considered in order to construct a solid theory adjusted to the facts and with less speculations and tortuous semantic traps.