New approaches to studying morphological details of intramolluscan stages of Angiostrongylus vasorum

Comparative biology of parasitic nematodes in the genus Angiostrongylus and related genera

The rise to prominence of some Angiostrongylus species through associated emerging disease in humans and dogs has stimulated calls for a renewed focus on the biology of this genus and three related genera. Although significant research efforts have been made in recent years these have tended to focus on individual species and specific aspects such as diagnosis and treatment of disease or new records of occurrence and hosts. This comprehensive review takes a comparative approach, seeking commonalities and differences among species and asking such questions as: Which species belong to this and to closely related genera and how are they related? Why do only some species appear to be spreading geographically and what factors might underlie range expansion? Which animal species are involved in the life cycles as definitive, intermediate, paratenic and accidental hosts? How do parasite larvae find, infect and develop within these hosts? What are the consequences of infection for host health? How will climate change affect future spread and global health? Appreciating how species resemble and differ from each other shines a spotlight on knowledge gaps and provides provisional guidance on key species characteristics warranting detailed study. Similarities exist among species, including the basic life cycle and transmission processes, but important details such as host range, climatic requirements, migration patterns within hosts and disease mechanisms differ, with much more information available for A. cantonensis and A. vasorum than for other species. Nonetheless, comparison across Angiostrongylus reveals some common patterns. Historically narrow definitive host ranges are expanding with new knowledge, combining with very broad ranges of intermediate gastropod hosts and vertebrate and invertebrate paratenic and accidental hosts to provide the backdrop to complex interactions among climate, ecology and transmission that remain only partly understood, even for the species of dominant concern. Key outstanding questions concern larval dynamics and the potential for transmission outside trophic relations, relations between infection and disease severity in different hosts, and how global change is altering transmission beyond immediate impacts on development rate in gastropods. The concept of encounter and compatibility filters could help to explain differences in the relative importance of different gastropod species as intermediate hosts and determine the importance of host community composition and related environmental factors to transmission and range. Across the group, it remains unclear what, physiologically, immunologically or taxonomically, delimits definitive, accidental and paratenic hosts. Impacts of infection on definitive host fitness and consequences for population dynamics and transmission remain mostly unexplored across the genus. Continual updating and cross-referencing across species of Angiostrongylus and related genera is important to synthesise rapid advances in understanding of key traits and behaviours, especially in important Angiostrongylus species that are emerging causative agents of disease in humans and other animals.

Nationwide Seroprevalence Survey of Angiostrongylus vasorum-Derived Antigens and Specific Antibodies in Dogs from Colombia

Angiostrongylus vasorum is a cardiopulmonary nematode, causing several clinical manifestations in dogs, e.g., severe respiratory signs, coagulopathy, and gastrointestinal or neurological signs. In the last decades, this parasite has been described to spread and emerge in Europe and North America. Scant studies on A. vasorum occurrence in South America exist. Recently, A. vasorum was detected in gastropod intermediate hosts in Colombia, where data on definitive host prevalence, e.g., dogs and wild canids, are still limited. Therefore, the sera of 955 dogs, varying in age and breed from seven different departments all over Colombia, were collected and analysed for A. vasorum antigens and parasite-specific antibodies by ELISA. In total, 1.05 % (n = 10; 95 % CI 0.40–1.69) of the samples were antigen-positive and 2.62 % (n = 25; 95 % CI 1.61–3.63) were antibody-positive. These results confirm the presence of A. vasorum in Colombia, although positive results in antigen and antibody reactions in the same dog were not detected. This study is the first large-scale survey on A. vasorum seroprevalences in dogs from Colombia.

The invasive giant African land snail, Achatina fulica (Gastropoda: Pulmonata): global geographical distribution of this species as host of nematodes of medical and veterinary importance

The giant African land snail, Achatina fulica, is an important invasive species in many countries, where it causes losses in biodiversity and agriculture, as well as impacting the health of both humans and animals, as the intermediate host of medically important nematodes. The present study is based on a comprehensive review of the literature on the nematodes that have been found in association with A. fulica, worldwide. We searched a number of different databases and used the findings to investigate the methods used to extract and identify the nematodes, their larval stages, and environment and collecting procedures of the infected molluscs. Between 1965 and 2021, 11 nematode species were recorded in association with A. fulica in 21 countries. Most of the studies recorded associations between A. fulica and Angiostrongylus cantonensis, which causes cerebral angiostrongyliasis in humans and Aelurostrongylus abstrusus, which provokes pneumonia in felines. The nematodes were extracted primarily by artificial digestion with hydrochloric acid or pepsin, and identified based on their morphology or through experimental infection to obtain the adult. In most cases, the nematodes were at larval stage L3, and the infected A. fulica were collected from anthropogenic environments. The results demonstrate the importance of A. fulica as a host of nematodes of medical and veterinary importance, as well the contribution of anthropogenic environments to the occurrence of the parasites, and give information about the different methods used to collect and identify the nematodes found associated with this species.