A longitudinal study of Angiostrongylus cantonensis in an urban population of Rattus norvegicus in Brazil: the influences of seasonality and host features on the pattern of infection

Older urban rats are infected with the zoonotic nematode Angiostrongylus cantonensis

Rats, being synanthropic, are hosts to agents of zoonotic diseases that pose a threat to human and domestic animal health. The nematode parasite Angiostrongylus cantonensis, commonly known as the rat lungworm, is no exception; it can cause potentially fatal neural disease in humans, dogs and other species. The distribution of A. cantonensis (haplotypes SYD.1 and Ac13) and its close relative, Angiostrongylus mackerrasae is not well understood in Australia. We investigated the prevalence of Angiostrongylus in rats in Sydney, Australia, primarily via faecal qPCR, and identified the species and haplotypes using partial cox1 sequencing. We found a moderate prevalence of infection (29%; 95% CI: 16.1-46.6%) in black (Rattus rattus) and brown (Rattus norvegicus) rats around public parks and residential areas. This study demonstrates that Sydney's urban rat population is a reservoir for A. cantonensis. Modelling infection status as a function of rat species, sex, tibia length (as a proxy for age), and health index (a measure of weight by size) revealed that older rats are statistically more likely to be infected (χ 2 1 = 5.331, P = 0.021). We observed a dominant presence of the A. cantonensis SYD.1 haplotype, for which the implications are not yet known. No A. mackerassae was detected, leading us to suspect it may have a more restricted host- and geographical range. Overall, this study illustrates the presence and potential risk of A. cantonensis infection in Sydney. Public education regarding transmission routes and preventative measures is crucial to safeguard human and animal health.

Parasite Fauna and Coinfections in Urban Rats Naturally Infected by the Zoonotic Parasite Angiostrongylus cantonensis

When the zoonotic parasite of rodents that can cause human neuroangiostrongyliasis, i.e., Angiostrongylus cantonensis, is found in its natural definitive hosts, it is usually reported in isolation, as if the rat lungworm were the only component of its parasite community. In this study, we report the coinfections found in rats naturally infected by A. cantonensis in urban populations of Rattus norvegicus and Rattus rattus in Valencia, Spain. In addition to the rat lungworms, which were found in 14 of the 125 rats studied (a prevalence of 11.20%), 18 other parasite species (intestinal and tissular protists, microsporidia and helminths) were found, some of them with high burdens. Fourteen of these nineteen species found are potential zoonotic parasites, namely Blastocystis, Giardia duodenalis, Cryptosporidium spp., Enterocytozoon bieneusi, Encephalitozoon hellem, Toxoplasma gondii, Brachylaima spp., Hydatigera taeniaeformis s.l. larvae, Hymenolepis nana, Hymenolepis diminuta, Angiostrongylus cantonensis, Calodium hepaticum, Gongylonema neoplasticum and Moniliformis moniliformis. The total predominance of coinfected rats as well as their high parasite loads seem to indicate a trend towards parasite tolerance.

Fatal neural angiostrongyliasis in the Bolivian squirrel monkey (Saimiri boliviensis boliviensis) leading to defining Angiostrongylus cantonensis risk map at a zoo in Australia

Neural angiostrongyliasis (NA) is a parasitic disease caused by Angiostrongylus cantonensis (rat lungworm). This study presents a case of NA in a captive Bolivian squirrel monkey from a zoo in western Sydney, Australia. The objective was to identify the A. cantonensis cox1 haplotype responsible for the infection and compare its mitochondrial DNA (mtDNA) to known Australian mtDNA. An epidemiological investigation was conducted to assess the risk of infection, focusing on the resident rat population in the zoo. Methods involved trapping rats and collecting rat faeces for Angiostrongylus detection, speciation, and cox1 haplotype confirmation. Various techniques were employed, including necropsy, morphological examination, and molecular methods such as ITS-2 qPCR, cox1 sequencing, and ITS-2 metabarcoding. Cluster analysis of rat faeces distribution and Angiostrongylus detection utilised an equal sampling effort (ESE) approach. Gastropods were collected throughout the study for Angiostrongylus surveillance using a hypersensitive qPCR assay. Results revealed significant clustering of rat faeces near exhibits with fresh food provision and absence of predators. Angiostrongylus-positive faeces were uniformly distributed across the zoo property. Mitochondrial DNA analysis confirmed the presence of the Ac13 haplotype of A. cantonensis in the monkey. Morphology, ITS-2 metabarcoding and partial cox1 sequencing detected only A. cantonensis, with the Ac13 cox1 haplotype predominating. A high prevalence of infection (64%, 9/14) was found in brown rats, with quantification of larvae indicating high shedding rates. Co-infections with both Ac13 and local SYD.1 A. cantonensis cox1 haplotypes were observed. Only three gastropods (all of which were Angiostrongylus-negative) were found in the survey. To minimise the risk of exposure for susceptible species, targeted rodent control was implemented in areas with higher exposure risk. A potential strategy (which requires further exploration) to consider for future zoo design was suggested. This study provides insights into the epidemiology and genetic diversity of A. cantonensis in Australia, emphasising the importance of control measures to prevent future outbreaks.

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.

Helminth community structure of Didelphis marsupialis (Didelphimorphia, Didelphidae) in a transition area between the Brazilian Amazon and the Cerrado

Although the common opossum, Didelphis marsupialis (Didelphimorphia: Didelphidae) is a species widely distributed in South America, knowledge about their helminth parasites and helminth community structure is scarce. The aims of this study were to describe the species composition and analyze the structure of the helminth community of the common opossum in an area of the Amazonian Arc in northern Mato Grosso. The helminths were recovered, counted, and identified in 32 individuals. Overall, 10,198 specimens were categorized into 9 helminths taxa (seven nematodes, one cestode, and one acanthocephalan). The most abundant species were Aspidodera raillieti, Viannaia hamata, and Travassostrongylus orloffi. No statistically significant differences in helminth abundance and prevalence were observed between host sexes. However, young hosts had higher abundance and prevalence of Didelphonema longispiculata, whereas Oligacanthorhynchus microcephalus had higher abundance and prevalence in adult hosts. This was the first study to analyze the helminth fauna and helminth community structure of D. marsupialis in the Amazonian Arc. This is the first report of the presence of A. raillieti, D. longispiculata, T. orloffi, T. minuta, V. hamata, and O. microcephalus in the state of Mato Grosso, Brazil.

Gleasonian structure in the helminth metacommunity of the opossum Didelphis albiventris in two extremes of the Atlantic Forest

Didelphis albiventris is the opossum with the largest geographic distribution in Brazil and has a wide spectrum of helminth parasites. This study aimed to describe the species composition and analyse the structure of helminth communities of D. albiventris in two extremes of the Atlantic Forest in Brazil. The influence of host sex, body mass, age, helminth species richness and locality on the abundance and prevalence of the most prevalent helminth species was investigated. Ninety-five per cent of the animals were infected with at least one species. Nine helminth species were found: the nematodes Aspidodera raillieti, Cruzia tentaculata, Trichuris didelphis and Trichuris minuta in the large intestine; Turgida turgida in the stomach; Travassostrongylus orloffi and Viannaia hamata; and the trematodes Brachylaima advena and Rhopalias coronatus in the small intestine. Three helminth morphospecies were also recovered: the nematodes Hoineffia sp. and Viannaia sp. and a cestode in the small intestine. Cruzia tentaculata and V. hamata were the species with the highest mean abundances and intensities, while the most prevalent species were A. raillieti, C. tentaculata, T. turgida and V. hamata, forming the central nucleus of the helminth component community. The analysis of the helminth metacommunity structure indicated a Gleasonian pattern for the total set of infracommunities, corroborating the beta diversity indices, which indicated more species replacement than loss between localities and infracommunities, although at a low level. The results indicated a stronger influence of host attributes than geographical distance on the community structure.

Composition and structure of the helminth community of rodents in matrix habitat areas of the Atlantic forest of southeastern Brazil

The predominant landscape of the Atlantic Forest of the Brazilian state of Rio de Janeiro is made up of forest fragments surrounded by a matrix of modified habitat, which may influence the occurrence and distribution of host species and their parasites in comparison with the original continuous forest. The present study describes the structure, composition, and diversity of the helminth community found in rodents in two areas of an open matrix of different status of conservation. The abundance, intensity, and prevalence were calculated for each helminth species in rodent species. The influence of biotic and abiotic factors on the abundance and prevalence of the helminth species was also investigated. Community structure was analyzed based on the beta diversity and a bipartite network. Nine helminth species were recovered from Akodon cursor, Necromys lasiurus and Mus musculus, with the greatest helminth species richness being recorded in A. cursor (S = 8), followed by N. lasiurus (S = 6), and M. musculus (S = 3). Only three of the helminths recorded in A. cursor had been recorded previously in this rodent in the Atlantic Forest, where 12 different helminths have been recorded, so that the other five are new occurrences for this rodent. All the helminth species of N. lasiurus had been reported previously in this rodent in the Cerrado and Caatinga regions. Mus musculus was infected with the same helminths as the local fauna. Host species and locality were the most important factors influencing helminth abundance and prevalence. Beta-diversity was high for infracommunities indicating more substitutions of helminth species than losses among individuals. Three helminths species were shared by the three host species. The reduced beta-diversity observed in the component communities was consistent with the overlap observed in the helminth fauna of the host species.

Angiostrongylus cantonensis in urban populations of terrestrial gastropods and rats in an impoverished region of Brazil

The nematode Angiostrongylus cantonensis is the most common cause of neuroangiostrongyliasis (manifested as eosinophilic meningitis) in humans. Gastropod molluscs are used as intermediate hosts and rats of various species are definitive hosts of this parasite. In this study, we identified several environmental factors associated with the presence and abundance of terrestrial gastropods in an impoverished urban region in Brazil. We also found that body condition, age and presence of co-infection with other parasite species in urban Rattus norvegicus, as well as environmental factors were associated with the probability and intensity of A. cantonensis infection. The study area was also found to have a moderate prevalence of the nematode in rodents (33% of 168 individuals). Eight species of molluscs (577 individuals) were identified, four of which were positive for A. cantonensis. Our study indicates that the environmental conditions of poor urban areas (presence of running and standing water, sewage, humidity and accumulated rain and accumulation of construction materials) influenced both the distribution and abundance of terrestrial gastropods, as well as infected rats, contributing to the maintenance of the A. cantonensis transmission cycle in the area. Besides neuroangiostrongyliasis, the presence of these hosts may also contribute to susceptibility to other zoonoses.

Variation in Angiostrongylus cantonensis infection in definitive and intermediate hosts in Hawaii, a global hotspot of rat lungworm disease

Angiostrongylus cantonensis (rat lungworm) is a tropical and subtropical parasitic nematode, with infections in humans causing angiostrongyliasis (rat lungworm disease), characterized by eosinophilic meningitis. Hawaii has been identified as a global hotspot of infection, with recent reports of high infection rates in humans, as well as rat definitive and snail intermediate hosts. This study investigated variation in A. cantonensis infection, both prevalence and intensity, in wild populations of two species of rats (Rattus exulans and R. rattus) and one species of snail (Parmarion martensi). An overall infection prevalence of 86.2% was observed in P. martensi and 63.8% in rats, with R. exulans (77.4%) greater than R. rattus (47.6%). We found infections to vary with environmental and host-related factors. Body mass was a strong predictor of infection in all three species, with different patterns seen between sexes and species of rats. Infection prevalence and intensity for R. exulans were high in May 2018 and again in February 2019, but generally lower and more variable during the intervening months. Information on sources of variability of infection in wild host populations will be a crucial component in predicting the effectiveness of future disease surveillance or targeted management strategies.

First record of natural infection by Angiostrongylus cantonensis (Nematoda: Metastrongyloidea) in Belocaulus willibaldoi and Rattus norvegicus in an urban area of São Paulo city, SP, Brazil

Angiostrongylus cantonensis, a rat lungworm, is one of the leading causes of eosinophilic meningitis in humans. Infection in humans occurs by the ingestion of intermediate hosts, undercooked paratenic hosts or contaminated vegetables and fruits by mucus from infected molluscs. This zoonosis is widespread in tropical and subtropical areas of Southeast Asia, it has also been reported in the Pacific Islands as well as in other regions of Americas. In Brazil, human cases of angiostrongyliasis have been reported since 2007 in Southeast, Northeast, and South regions. In January 2011, we collected a batch of 30 Belocaulus willibaldoi slides in a neighborhood of São Paulo city (Parque Fernanda). Six of them were used for identifying species, and the others (24) were used in parasitological tests through digestion in peptic solution and then larvae isolation by the Rugai method. A total of 250 larvae were obtained and they had morphological traits of Angiostrongylus spp. Later, four Golden hamsters (Mesocricetus auratus) were infected with 38 larvae that allowed the recovery of young worms from the brain and lungs of rodents on the 21^st and 30^th day of infection. In this same neighborhood we captured rodents (Rattus norvegicus) that, after necropsy led us to recovery of 22 adult worms in the pulmonary arteries (14 males and 8 females) in May 2011. The larvae and worms obtained from natural infection were evaluated by morphological and morphometric parameters, as well as biological behavior patterns and molecular profile. All methodologies identified the parasite as Angiostrongylus cantonensis. In this way, we report for the first time, the natural infection by A. cantonensis in intermediate (B. willibaldoi) and definitive (R. norvegicus) hosts in a new urban region of Brazil.

Survey of Angiostrongylus cantonensis Infection Status in Host Animals and Populations in Shenzhen, 2016-2017

The study was to understand Angiostrongylus cantonensis infection status in host animals and populations in Shenzhen. In 2016-2017, 10 different ecological environments were selected, and intermediate and definitive hosts collected at the sites were examined using the enzyme digestion and dissection method to determine their infection status. Meanwhile, serum was collected from outpatients and healthy people. The enzyme-linked immunosorbent assay test was performed to detect serum IgG-specific antibodies to A. cantonensis, and serological characteristics of the populations were analyzed. A total of 300 Achatina fulica samples had an A. cantonensis infection rate of 10.67% (32/300) and an average infection intensity of 68.7 per snail, whereas 302 Pomacea canaliculata samples had an infection rate of 6.29% (19/302) and an average infection intensity of 31.4 per snail. Although both infection rate and infection intensity were lower in P. canaliculata than in A. fulica, infection intensity was significantly different (p < 0.001). Among 238 definitive-host rodents, 22 were infected with A. cantonensis. The infection rate in Rattus norvegicus was 14.68% (16/109), significantly higher than that in Rattus flavipectus (p < 0.05). The seroprevalence of A. cantonensis in the 900 outpatients and 1500 healthy people was 7.11% (64/900) and 1.87% (28/1500), respectively. Thus, the infection rate was significantly higher in outpatients than in healthy people in Shenzhen (p < 0.001). This study revealed a wide distribution and the prevalence of A. cantonensis in host animals and populations in Shenzhen, therefore, it is necessary to strengthen the current monitoring of the disease to prevent a potential outbreak.

Angiostrongylus (Parastrongylus) cantonensis on intermediate and definitive hosts in Ecuador, 2014-2017

Introduction: Angiostrongylus cantonensis is a serious public health problem and is widely distributed in the country. When the parasite infects the snails, it becomes deeply embedded in their interior and accidentally, it can infect people and other mammals. Objective: To establish the geographical distribution of A. cantonensis intermediate hosts (Achatina fulica) and definitive hosts (Rattus spp.) in Ecuador from 2014 to 2017. Materials and methods: We collected 2,908 A. fulica specimens in 16 provinces using the capture method per unit of effort for 30 minutes. We captured 211 hosts of which 20 were Rattus rattus and 191 R. norvegicus. The specimens were transported to the Instituto Nacional de Salud Pública e Investigación in Guayaquil where the larvae L3 were identified and counted in the tissues of the snail, which were then inoculated in laboratory rats to reproduce the life cycle. In the rodents, the brains, hearts, lung arteries and lungs were dissected, and the parasites were identified by taxonomic morphology. Results: Of the snails harvested, 441 were positive for A. cantonensis (15.2%) and a total of 6,166 L3 larvae were found; 77 (36.5%) specimens of Rattus spp., were infected with A. cantonensis and a total of 220 parasites (L4-L5 larvae and adult worms) were collected. Conclusions: We confirmed the presence of A. cantonensis in several provinces, which ratifies the endemic nature of this zoonosis in the national territory. Rattus spp. specimens constitute the definitive hosts of the parasite, which together with the presence of intermediate hosts, indicates the zoonotic potential of this parasitic infection.

Variation in the prevalence and abundance of acanthocephalans in brown-nosed coatis Nasua nasua and crab-eating foxes Cerdocyon thous in the Brazilian Pantanal

Host infection by parasites is influenced by an array of factors, including host and environmental features. We investigated the relationship between host sex, body size and age, as well as seasonality on infection patterns by acanthocephalan in coatis (Procyonidae: Nasua nasua) and in crab-eating foxes (Canidae: Cerdocyon thous ) from the Brazilian Pantanal wetlands. Between 2006 and 2009, we collected faecal samples from these hosts and analyzed for the presence of acanthocephalan eggs. Prevalence, abundance and intensity of eggs of acanthocephalans were calculated. Egg abundance was analyzed using generalized linear models (GLM) with a negative binomial distribution and models were compared by Akaike criteria to verify the effect of biotic and abiotic factors. Prevalence of acanthocephalans was higher in the wet season in both host species but did not differ between host sexes; however, adult crab-eating foxes showed higher prevalence of acanthocephalan eggs than juveniles. In contrast, prevalence of acanthocephalan eggs found in coatis was higher in coati juveniles than in adults. Host age, season and maximum temperature were the top predictors of abundance of acanthocephalan eggs in crab-eating foxes whereas season and host sex were predictors of egg abundance in coatis. The importance of seasonality for abundance of acanthocephalan was clear for both host species. The influence of host-related attributes, however, varied by host species, with host gender and host age being important factors associated with prevalence and parasite loads.

Small-scale spatial analysis of intermediate and definitive hosts of Angiostrongylus cantonensis

BACKGROUND

Angiostrongyliasis is a food-borne parasitic zoonosis. Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis. The life cycle of A. cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts. This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts, which are key components in the strategy for the prevention and control of angiostrongyliasis.

METHODS

Three villages from Nanao Island, Guangdong Province, China, were chosen as study area by stratified random sampling. The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016, with spatial correlations of the positive P. canaliculata and the infection rates analysed by ArcGIS, scan statistics, ordinary least squares (OLS) and geographically weighted regression (GWR) models.

RESULTS

A total of 2192 P. canaliculata specimens were collected from the field, of which 1190 were randomly chosen to be examined for third-stage larvae of A. cantonensis. Seventy-two Angiostrongylus-infected snails were found, which represents a larval infection rate of 6.1% (72/1190). In total, 110 rats including 85 Rattus norvegicus, 10 R. flavipectus, one R. losea and 14 Suncus murinus were captured, and 32 individuals were positive (for adult worms), representing an infection rate of 29.1% of the definitive hosts (32/110). Worms were only found in R. norvegicus and R. flavipectus, representing a prevalence of 36.5% (31/85) and 10% (1/10), respectively in these species, but none in R. losea and S. murinus, despite testing as many as 32 of the latter species. Statistically, spatial correlation and spatial clusters in the spatial distribution of positive P. canaliculata and positive rats existed. Most of the spatial variability of the host infection rates came from spatial autocorrelation. Nine spatial clusters with respect to positive P. canaliculata were identified, but only two correlated to infection rates. The results show that corrected Akaike information criterion, R², R² adjusted and σ² in the GWR model were superior to those in the OLS model.

CONCLUSIONS

P. canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts, demonstrating that there was a risk of angiostrongyliasis in this region of China. The distribution of positive P. canaliculata and rats exhibited spatial correlation, and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A. cantonensis.

Metacommunity structure of the helminths of the black-eared opossum Didelphis aurita in peri-urban, sylvatic and rural environments in south-eastern Brazil

Among the Brazilian marsupials, the species of the genus Didelphis are the most parasitized by helminths. This study aimed to describe the species composition and to analyse the helminth communities of the Atlantic Forest common opossum Didelphis aurita at infracommunity and component community levels using the Elements of Metacommunity Structure Analysis, considering peri-urban, sylvatic and rural environments in the state of Rio de Janeiro, Brazil. Seventy-three specimens of D. aurita were captured during the study. Fourteen species of helminths were collected: nine of the phylum Nematoda (Trichuris minuta, Trichuris didelphis, Globocephalus marsupialis, Heterostrongylus heterostrongylus, Travassostrongylus orloffi, Viannaia hamata, Aspidodera raillieti, Cruzia tentaculata and Turgida turgida); four of the phylum Platyhelminthes (three species of Trematoda, Duboisiella proloba, Brachylaima advena and Rhopalias coronatus, and one species of the class Cestoda); and one species of the phylum Acanthocephala (Oligacanthorhynchus microcephalus). More than 95% of the animals were infected with parasites. The most abundant parasite species were V. hamata, T. turgida, C. tentaculata and T. orloffi. The nematodes T. turgida, C. tentaculata and A. raillieti were the most dominant species in the three environments. The analysis of the metacommunity structure indicated a structured pattern as a function of the environmental gradient, but only when all localities were considered together. At the infracommunity and component community levels, quasi-nested and nested structures with stochastic species loss were observed, respectively. The results indicate that the settlement of helminth species in the opossums can be attributed to the heterogeneity among individual hosts in relation to their exposure to parasites and to extrinsic factors, which vary among habitats, considering a regional scale. On a local scale, the characteristics of this host species may promote homogenization among individual hosts in terms of their exposure to the helminths. This study constitutes a new host record for the species G. marsupialis and T. didelphis and represents a pioneering investigation of the helminth metacommunity of a Neotropical marsupial.

Achatina fulica infected by Angiostrongylus cantonensis on beaches, in the west zone of Rio de Janeiro, Brazil

Angiostrongylus cantonensis is considered the main etiological agent of eosinophilic meningitis in humans. At present, this zoonosis is considered an emerging disease mainly in the Americas. The aim of this study was to determine the prevalence of Achatina fulica infected by Angiostrongylus cantonensis in restinga areas along beaches in the west zone of Rio de Janeiro city, Brazil. The study areas included the following beaches: Barra da Tijuca, Recreio dos Bandeirantes, Reserva, Prainha and Grumari. Ninety specimens of Achatina fulica were collected. Positive molluscs were found only in Barra da Tijuca. Infection prevalence was 5.5%. The presence of this parasite in the beachfront areas, in the west zone of Rio de Janeiro city demonstrates the potential risk of infection for visitors and the expansion of this helminth in the State of Rio de Janeiro.

High prevalence of Angiostrongylus cantonensis (rat lungworm) on eastern Hawai'i Island: A closer look at life cycle traits and patterns of infection in wild rats (Rattus spp.)

The nematode Angiostrongylus cantonensis is a zoonotic pathogen and the etiological agent of human angiostrongyliasis or rat lungworm disease. Hawai'i, particularly east Hawai'i Island, is the epicenter for angiostrongyliasis in the USA. Rats (Rattus spp.) are the definitive hosts while gastropods are intermediate hosts. The main objective of this study was to collect adult A. cantonensis from wild rats to isolate protein for the development of a blood-based diagnostic, in the process we evaluated the prevalence of infection in wild rats. A total of 545 wild rats were sampled from multiple sites in the South Hilo District of east Hawai'i Island. Adult male and female A. cantonensis (3,148) were collected from the hearts and lungs of humanely euthanized Rattus rattus, and R. exulans. Photomicrography and documentation of multiple stages of this parasitic nematode in situ were recorded. A total of 45.5% (197/433) of rats inspected had lung lobe(s) (mostly upper right) which appeared granular indicating this lobe may serve as a filter for worm passage to the rest of the lung. Across Rattus spp., 72.7% (396/545) were infected with adult worms, but 93.9% (512/545) of the rats were positive for A. cantonensis infection based on presence of live adult worms, encysted adult worms, L3 larvae and/or by PCR analysis of brain tissue. In R. rattus we observed an inverse correlation with increased body mass and infection level of adult worms, and a direct correlation between body mass and encysted adult worms in the lung tissue, indicating that larger (older) rats may have developed a means of clearing infections or regulating the worm burden upon reinfection. The exceptionally high prevalence of A. cantonensis infection in Rattus spp. in east Hawai'i Island is cause for concern and indicates the potential for human infection with this emerging zoonosis is greater than previously thought.

Parasites as bioindicators of environmental degradation in Latin America: A meta-analysis

Unregulated economic growth in Latin America has resulted in environmental degradation, including the release of toxic compounds into the environment. One strategy to understand and prevent the outcomes of this harmful environmental degradation is the use of bioindicators. These are free-living or parasite species that respond to habitat alterations with changes in their numbers, physiology or chemical composition. The aim of this review was to determine whether there is evidence of a significant parasite response to environmental damage in Latin America. We collected 26 papers published between 2003 and 2015 and conducted a meta-analysis to test the null hypothesis that there is no significant overall effect of environmental insults on parasites. The meta-analysis showed a low but still significant negative mean overall effect (Hedges' g = -0.221; 95% CI: -0.241 to -0.200; P < 0.0001). However, the magnitudes and directions of the significant effects varied widely. These results suggest that different groups of parasites have distinct responses to various environmental insults and that the groups should be separately analysed after the accumulation of a sufficient number of studies. For future studies on this topic in Latin America, we suggest: (1) using field and experimental approaches to determine the response of parasites to environmental degradation; (2) using an interdisciplinary approach, including different types of biomarkers in both parasites and individual hosts to generate long-term datasets in polluted and reference areas; (3) conducting studies on parasites as accumulation bioindicators.

Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen

Angiostrongylus cantonensis is a metastrongyloid nematode found widely in the Asia-Pacific region, and the aetiological agent of angiostrongyliasis; a disease characterized by eosinophilic meningitis. Rattus rats are definitive hosts of A. cantonensis, while intermediate hosts include terrestrial and aquatic molluscs. Humans are dead-end hosts that usually become infected upon ingestion of infected molluscs. A presumptive diagnosis is often made based on clinical features, a history of mollusc consumption, eosinophilic pleocytosis in cerebral spinal fluid, and advanced imaging such as computed tomography. Serological tests are available for angiostrongyliasis, though many tests are still under development. While there is no treatment consensus, therapy often includes a combination of anthelmintics and corticosteroids. Angiostrongyliasis is relatively rare, but is often associated with morbidity and sometimes mortality. Recent reports suggest the parasites' range is increasing, leading to fatalities in regions previously considered Angiostrongylus-free, and sometimes, delayed diagnosis in newly invaded regions. Increased awareness of angiostrongyliasis would facilitate rapid diagnosis and improved clinical outcomes. This paper summarizes knowledge on the parasites' life cycle, clinical aspects and epidemiology. The molecular biology of Angiostrongylus spp. is also discussed. Attention is paid to the significance of angiostrongyliasis in Australia, given the recent severe cases reported from the Sydney region.

The Increase of Exotic Zoonotic Helminth Infections: The Impact of Urbanization, Climate Change and Globalization

Zoonotic parasitic diseases are increasingly impacting human populations due to the effects of globalization, urbanization and climate change. Here we review the recent literature on the most important helminth zoonoses, including reports of incidence and prevalence. We discuss those helminth diseases which are increasing in endemic areas and consider their geographical spread into new regions within the framework of globalization, urbanization and climate change to determine the effect these variables are having on disease incidence, transmission and the associated challenges presented for public health initiatives, including control and elimination.

Angiostrongylus cantonensis infection in molluscs in the municipality of São Gonçalo, a metropolitan area of Rio de Janeiro, Brazil: role of the invasive species Achatina fulica in parasite transmission dynamics

The aim of this study was to analyse the infection dynamics of Angiostrongylus cantonensisin its possible intermediate hosts over two years in an urban area in the state of Rio de Janeiro where the presence ofA. cantonensis had been previously recorded in molluscs. Four of the seven mollusc species found in the study were exotic.Bradybaena similaris was the most abundant, followed by Achatina fulica, Streptaxis sp., Subulina octona, Bulimulus tenuissimus, Sarasinula linguaeformis and Leptinaria unilamellata. Only A. fulica and B. similaris were parasitised by A. cantonensis and both presented co-infection with other helminths. The prevalence of A. cantonensis in A. fulica was more than 50% throughout the study. There was an inverse correlation between the population size ofA. fulica and the prevalence of A. cantonensis and abundance of the latter was negatively related to rainfall. The overall prevalence of A. cantonensis in B. similaris was 24.6%. A. fulica was the most important intermediary host of A. cantonensis in the studied area and B. similaris was secondary in importance for A. cantonensis transmission dynamics.

The Prevalence of Angiostrongylus cantonensis/mackerrasae Complex in Molluscs from the Sydney Region

Angiostrongylus cantonensis and Angiostrongylus mackerrasae are metastrongyloid nematodes that infect various rat species. Terrestrial and aquatic molluscs are intermediate hosts of these worms while humans and dogs are accidental hosts. Angiostrongylus cantonensis is the major cause of angiostrongyliasis, a disease characterised by eosinophilic meningitis. Although both A. cantonensis and A. mackerrasae are found in Australia, A. cantonensis appears to account for most infections in humans and animals. Due to the occurrence of several severe clinical cases in Sydney and Brisbane, the need for epidemiological studies on angiostrongyliasis in this region has become apparent. In the present study, a conventional PCR and a TaqMan assay were compared for their ability to amplify Angiostrongylus DNA from DNA extracted from molluscs. The TaqMan assay was more sensitive, capable of detecting the DNA equivalent to one hundredth of a nematode larva. Therefore, the TaqMan assay was used to screen molluscs (n=500) of 14 species collected from the Sydney region. Angiostrongylus DNA was detected in 2 of the 14 mollusc species; Cornu aspersum [14/312 (4.5%)], and Bradybaenia similaris [1/10 (10%)], which are non-native terrestrial snails commonly found in urban habitats. The prevalence of Angiostrongylus spp. was 3.0% ± 0.8% (CI 95%). Additionally, experimentally infected Austropeplea lessoni snails shed A. cantonensis larvae in their mucus, implicating mucus as a source of infection. This is the first Australian study to survey molluscs using real-time PCR and confirms that the garden snail, C. aspersum, is a common intermediate host for Angiostrongylus spp. in Sydney.

Detection of Angiostrongylus cantonensis in the Blood and Peripheral Tissues of Wild Hawaiian Rats (Rattus rattus) by a Quantitative PCR (qPCR) Assay

The nematode Angiostrongylus cantonensis is a rat lungworm, a zoonotic pathogen that causes human eosinophilic meningitis and ocular angiostrongyliasis characteristic of rat lungworm (RLW) disease. Definitive diagnosis is made by finding and identifying A. cantonensis larvae in the cerebral spinal fluid or by using a custom immunological or molecular test. This study was conducted to determine if genomic DNA from A. cantonensis is detectable by qPCR in the blood or tissues of experimentally infected rats. F1 offspring from wild rats were subjected to experimental infection with RLW larvae isolated from slugs, then blood or tissue samples were collected over multiple time points. Blood samples were collected from 21 rats throughout the course of two trials (15 rats in Trial I, and 6 rats in Trial II). In addition to a control group, each trial had two treatment groups: the rats in the low dose (LD) group were infected by approximately 10 larvae and the rats in the high dose (HD) group were infected with approximately 50 larvae. In Trial I, parasite DNA was detected in cardiac bleed samples from five of five LD rats and five of five HD rats at six weeks post-infection (PI), and three of five LD rats and five of five HD rats from tail tissue. In Trial II, parasite DNA was detected in peripheral blood samples from one of two HD rats at 53 minutes PI, one of two LD rats at 1.5 hours PI, one of two HD rats at 18 hours PI, one of two LD rats at five weeks PI and two of two at six weeks PI, and two of two HD rats at weeks five and six PI. These data demonstrate that parasite DNA can be detected in peripheral blood at various time points throughout RLW infection in rats.

Biotic and abiotic effects on the intestinal helminth community of the brown rat Rattus norvegicus from Rio de Janeiro, Brazil

Rattus norvegicus has attracted much attention because of its role as a reservoir of zoonotic pathogens. This work aimed to identify the intestinal helminth species in R. norvegicus and to analyse the effects of temperature, rainfall, host age and sex on the helminth community structure. Moreover, this study investigated the possible associations among helminth species in an urban population of R. norvegicus in São Gonçalo, Rio de Janeiro, sampled during the rainy and dry seasons over a span of 2 years. A total of 112 rats were infected by six species of helminths. The nematode Nippostrongylus brasiliensis was the most prevalent and abundant species, with high mean intensity in both seasons, followed by Strongyloides venezuelensis, Heterakis spumosa, Raillietina sp., Hymenolepis nana and Moniliformis moniliformis. Co-occurrence was found between N. brasiliensis and S. venezuelensis and between N. brasiliensis and H. spumosa. The occurrence of S. venezuelensis was related to rainfall. The understanding of the helminth community structure in this synanthropic rat provides basic information on parasites of public health importance, as two helminth species (H. nana and M. moniliformis) recovered from rats in the urban area studied can infect humans.