Detection of Trypanosoma lewisi DNA from Rattus norvegicus and Rattus rattus in Hanoi, Vietnam.

Trypanosoma lewisi is a worldwide nonpathogenic parasite that is exclusively found in rats. In general, T. lewisi infection in humans is an opportunistic infection from rats to humans through fleas. However, recently, infection with T. lewisi in humans, including a fatal case, has been reported. Notably, rats living close to a human settlement showed a higher prevalence of infection with T. lewisi than those living in other places. It is possible that the urbanization is associated with the prevalence of T. lewisi in rats and enhances the risk of T. lewisi transmission to humans through fleas. In this study, a total of 88 rats were captured from hospitals, markets, and a cargo station, of which 81 were identified as Rattus norvegicus and 7 as Rattus rattus in Hanoi, the urbanizing city of Vietnam. Of these, 55 rats (62.5%) harbored T. lewisi, of which 52 were R. norvegicus and 3 were R. rattus.

Assessing rodents as carriers of pathogenic Leptospira species in the U.S. Virgin Islands and their risk to animal and public health.

Leptospirosis is a global zoonotic disease caused by pathogenic bacteria of the genus Leptospira. We sought to determine if rodents in U.S. Virgin Islands (USVI) are carriers of Leptospira. In total, 140 rodents were sampled, including 112 Mus musculus and 28 Rattus rattus. A positive carrier status was identified for 64/140 (45.7%); 49 (35.0%) were positive by dark-field microscopy, 60 (42.9%) by culture, 63 (45.0%) by fluorescent antibody testing, and 61 (43.6%) by real-time polymerase chain reaction (rtPCR). Molecular typing indicated that 48 isolates were L. borgpetersenii and 3 were L. kirschneri; the remaining nine comprised mixed species. In the single culture-negative sample that was rtPCR positive, genotyping directly from the kidney identified L. interrogans. Serotyping of L. borgpetersenii isolates identified serogroup Ballum and L. kirschneri isolates as serogroup Icterohaemorrhagiae. These results demonstrate that rodents are significant Leptospira carriers and adds to understanding the ecoepidemiology of leptospirosis in USVI.

Inoculation route-dependent Lassa virus dissemination and shedding dynamics in the natural reservoir - Mastomys natalensis.

Lassa virus (LASV), a Risk Group-4 zoonotic haemorrhagic fever virus, affects sub-Saharan African countries. Lassa fever, caused by LASV, results in thousands of annual deaths. Although decades have elapsed since the identification of the Natal multimammate mouse (Mastomys natalensis) as a natural reservoir of LASV, little effort has been made to characterize LASV infection in its reservoir. The natural route of infection and transmission of LASV within M. natalensis remains unknown, and the clinical impact of LASV in M. natalensis is mostly undescribed. Herein, using an outbred colony of M. natalensis, we investigate the replication and dissemination dynamics of LASV in this reservoir following various inoculation routes. Inoculation with LASV, regardless of route, resulted in a systemic infection and accumulation of abundant LASV-RNA in many tissues. LASV infection in the Natal multimammate mice was subclinical, however, clinical chemistry values were transiently altered and immune infiltrates were observed histologically in lungs, spleens and livers, indicating a minor disease with coordinated immune responses are elicited, controlling infection. Intranasal infection resulted in unique virus tissue dissemination dynamics and heightened LASV shedding, compared to subcutaneous inoculation. Our study provides important insights into LASV infection in its natural reservoir using a contemporary infection system, demonstrating that specific inoculation routes result in disparate dissemination outcomes, suggesting intranasal inoculation is important in the maintenance of LASV in the natural reservoir, and emphasizes that selection of the appropriate inoculation route is necessary to examine aspects of viral replication, transmission and responses to zoonotic viruses in their natural reservoirs.

Modeling SARS-CoV-2 propagation using rat coronavirus-associated shedding and transmission.

At present, global immunity to SARS-CoV-2 resides within a heterogeneous combination of susceptible, naturally infected and vaccinated individuals. The extent to which viral shedding and transmission occurs on re-exposure to SARS-CoV-2 is an important determinant of the rate at which COVID-19 achieves endemic stability. We used Sialodacryoadenitis Virus (SDAV) in rats to model the extent to which immune protection afforded by prior natural infection via high risk (inoculation; direct contact) or low risk (fomite) exposure, or by vaccination, influenced viral shedding and transmission on re-exposure. On initial infection, we confirmed that amount, duration and consistency of viral shedding, and seroconversion rates were correlated with exposure risk. Animals were reinfected after 3.7-5.5 months using the same exposure paradigm. 59% of seropositive animals shed virus, although at lower amounts. Previously exposed seropositive reinfected animals were able to transmit virus to 25% of naive recipient rats after 24-hour exposure by direct contact. Rats vaccinated intranasally with a related virus (Parker's Rat Coronavirus) were able to transmit SDAV to only 4.7% of naive animals after a 7-day direct contact exposure, despite comparable viral shedding. Cycle threshold values associated with transmission in both groups ranged from 29-36 cycles. Observed shedding was not a prerequisite for transmission. Results indicate that low-level shedding in both naturally infected and vaccinated seropositive animals can propagate infection in susceptible individuals. Extrapolated to COVID-19, our results suggest that continued propagation of SARS-CoV-2 by seropositive previously infected or vaccinated individuals is possible.

Tracing Transmission of Sin Nombre Virus and Discovery of Infection in Multiple Rodent Species.

Sin Nombre orthohantavirus (SNV), a negative-sense, single-stranded RNA virus that is carried and transmitted by the North American deer mouse Peromyscus maniculatus, can cause infection in humans through inhalation of aerosolized excreta from infected rodents. This infection can lead to hantavirus cardiopulmonary syndrome (HCPS), which has an ∼36% case-fatality rate. We used reverse transcriptase quantitative PCR (RT-qPCR) to confirm SNV infection in a patient and identified SNV in lung tissues in wild-caught rodents from potential sites of exposure. Using viral whole-genome sequencing (WGS), we identified the likely site of transmission and discovered SNV in multiple rodent species not previously known to carry the virus. Here, we report, for the first time, the use of SNV WGS to pinpoint a likely site of human infection and identify SNV simultaneously in multiple rodent species in an area of known host-to-human transmission. These results will impact epidemiology and infection control for hantaviruses by tracing zoonotic transmission and investigating possible novel host reservoirs. IMPORTANCE Orthohantaviruses cause severe disease in humans and can be lethal in up to 40% of cases. Sin Nombre orthohantavirus (SNV) is the main cause of hantavirus disease in North America. In this study, we sequenced SNV from an infected patient and wild-caught rodents to trace the location of infection. We also discovered SNV in rodent species not previously known to carry SNV. These studies demonstrate for the first time the use of virus sequencing to trace the transmission of SNV and describe infection in novel rodent species.

Hantavirus Research in Finland: Highlights and Perspectives.

Finland has the highest incidence of hantavirus infections globally, with a significant impact on public health. The large coverage of boreal forests and the cyclic dynamics of the dominant forest rodent species, the bank vole Myodes glareolus, explain most of this. We review the relationships between Puumala hantavirus (PUUV), its host rodent, and the hantavirus disease, nephropathia epidemica (NE), in Finland. We describe the history of NE and its diagnostic research in Finland, the seasonal and multiannual cyclic dynamics of PUUV in bank voles impacting human epidemiology, and we compare our northern epidemiological patterns with those in temperate Europe. The long survival of PUUV outside the host and the life-long shedding of PUUV by the bank voles are highlighted. In humans, the infection has unique features in pathobiology but rarely long-term consequences. NE is affected by specific host genetics and risk behavior (smoking), and certain biomarkers can predict the outcome. Unlike many other hantaviruses, PUUV causes a relatively mild disease and is rarely fatal. Reinfections do not exist. Antiviral therapy is complicated by the fact that when symptoms appear, the patient already has a generalized infection. Blocking vascular leakage measures counteracting pathobiology, offer a real therapeutic approach.

Transmission of 'Candidatus Anaplasma camelii' to mice and rabbits by camel-specific keds, Hippobosca camelina.

Anaplasmosis, caused by infection with bacteria of the genus Anaplasma, is an important veterinary and zoonotic disease. Transmission by ticks has been characterized but little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence of Anaplasma spp. in camels in northern Kenya and whether the hematophagous camel ked, Hippobosca camelina, acts as a vector. Camels (n = 976) and > 10,000 keds were sampled over a three-year study period and the presence of Anaplasma species was determined by PCR-based assays targeting the Anaplasmataceae 16S rRNA gene. Camels were infected by a single species of Anaplasma, 'Candidatus Anaplasma camelii', with infection rates ranging from 63-78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10-29% of camel keds harbored 'Ca. Anaplasma camelii' acquired from infected camels during blood feeding. We determined that Anaplasma-positive camel keds could transmit 'Ca. Anaplasma camelii' to mice and rabbits via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by microscopic observation in blood smears and by PCR. Transmission of 'Ca. Anaplasma camelii' to mice (8-47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential of H. camelina as a vector of anaplasmosis. This key finding provides the rationale for establishing ked control programmes for improvement of livestock and human health.

Prevalence of Orthohantavirus-Reactive Antibodies in Humans and Peri-Domestic Rodents in Northern Ethiopia.

In 2012, Tigray orthohantavirus was discovered in Ethiopia, but its seasonal infection in small mammals, and whether it poses a risk to humans was unknown. The occurrence of small mammals, rodents and shrews, in human inhabitations in northern Ethiopia is affected by season and presence of stone bunds. We sampled small mammals in two seasons from low- and high-density stone bund fields adjacent to houses and community-protected semi-natural habitats in Atsbi and Hagere Selam, where Tigray orthohantavirus was first discovered. We collected blood samples from both small mammals and residents using filter paper. The presence of orthohantavirus-reactive antibodies in blood was then analyzed using immunofluorescence assay (human samples) and enzyme linked immunosorbent assays (small mammal samples) with Puumala orthohantavirus as antigen. Viral RNA was detected by RT-PCR using small mammal blood samples. Total orthohantavirus prevalence (antibodies or virus RNA) in the small mammals was 3.37%. The positive animals were three Stenocephalemys albipes rats (prevalence in this species = 13.04%). The low prevalence made it impossible to determine whether season and stone bunds were associated with orthohantavirus prevalence in the small mammals. In humans, we report the first detection of orthohantavirus-reactive IgG antibodies in Ethiopia (seroprevalence = 5.26%). S. albipes lives in close proximity to humans, likely increasing the risk of zoonotic transmission.

Revisiting the Pneumocystis host specificity paradigm and transmission ecology in wild Southeast Asian rodents.

Pneumocystis fungi are opportunistic parasites of mammalian lungs whose evolution, ecology and host specificity in natural host populations remain poorly understood and controversial. Using an extensive collection of 731 lung samples from 27 rodent species sampled in five Southeast Asian countries, and nested PCR amplification of mitochondrial and nuclear genes, we investigated the host specificity and genetic structure of Pneumocystis lineages infecting wild rodents. We also identified the rodent species playing a central role in the transmission of these parasites using network analysis and centrality measurement and we characterized the environmental conditions allowing Pneumocystis infection in Southeast Asia using generalized linear mixed models. Building upon an unprecedented Pneumocystis sampling from numerous rodent species belonging to closely related genera, our findings provide compelling evidence that the host specificity of Pneumocystis lineages infecting rodents is not restricted to a single host species or genus as often presented in the literature but it encompasses much higher taxonomic levels and more distantly related rodent host species. The phylogenetic species status at both mitochondrial and nuclear genetic markers of at least three new Pneumocystis lineages, highly divergent from Pneumocystis species currently described, is also suggested by our data. Our models show that the probability of Pneumocystis infection in rodent hosts is positively correlated to environmental variables reflecting habitat fragmentation and landscape patchiness. Synanthropic and habitat-generalist rodents belonging to the Rattus, Sundamys and Bandicota genera played a role of bridge host species for Pneumocystis spreading in these heterogeneous habitats, where they can reach high population densities. These are critical findings improving our understanding of the ecology of these enigmatic parasites and the role played by cospeciation and host switches in their evolution. Our results also confirmed the role of land-use change and habitat fragmentation in parasite amplification and spillover in rodents.

Central Nervous System and Ocular Manifestations in Puumala Hantavirus Infection.

Puumala hantavirus (PUUV), carried and spread by the bank vole (Myodes glareolus), causes a mild form of hemorrhagic fever with renal syndrome (HFRS) called nephropathia epidemica (NE). Acute high fever, acute kidney injury (AKI), thrombocytopenia, and hematuria are typical features of this syndrome. In addition, headache, blurred vision, insomnia, vertigo, and nausea are commonly associated with the disease. This review explores the mechanisms and presentations of ocular and central nervous system involvement in acute NE.

A scoping review of rodent-borne pathogen presence, exposure, and transmission at zoological institutions.

BACKGROUND: Rodents are one of the major taxa most likely to carry zoonotic diseases, harboring more than 85 unique zoonotic pathogens. While the significance of rodents' capacity to carry and transmit disease has been characterized in urban settings, the zoo environment is particularly unique given the overlap of collection, free-living, and feeder rodents as well as non-rodent collection animals, staff, and visitors. ELIGIBILITY CRITERIA: This scoping review examines reports of rodent-borne pathogen detection or transmission in zoo settings extracted from the literature. Papers were included in the final analysis if there was evidence of presence or exposure to a pathogen in a rodent at a zoological institution. SOURCES OF EVIDENCE: Publications were included from PubMed, CAB Abstracts and Biological Abstracts searched in August 2019. CHARTING METHODS: Data extracted from publications on pathogen presence/exposure included publication identifiers, study identifiers, infectious agent identifiers, rodent identifiers, and non-rodent collection animal identifiers. Extraction from papers with evidence of disease transmission included number of rodents involved in transmission, non-rodent collection animal species and numbers, and job title of humans involved, diagnostic tests performed, and clinical outcomes. RESULTS: Aggregate literature examined included 207 publications presenting evidence of pathogen presence and/or exposure in rodents across 43 countries in over 140 zoological institutions. A total of 143 infectious agent genera were identified, comprising 14 viral genera, 31 bacterial genera, 83 parasitic genera, and 15 fungal genera. Of these infectious agents, over 75 % were potentially zoonotic. The most common disease-causing agent genera identified were Leptospira, Toxoplasma, Salmonella, and Yersinia. Additional screening for evidence of pathogen transmission across species yielded 30 publications, indicating an area for future investigation to better inform surveillance and management priorities in order to reduce exposure, infection, and transmission. CONCLUSIONS: Analyzing the breadth of rodent species and pathogens identified at zoos highlights the unique opportunity zoos have to be at the forefront of the early detection and identification of novel hosts and geographic ranges of rodent-borne pathogens with high impact on both endangered species and people. The overlap of these populations at zoos exemplifies the importance of considering One Health when prioritizing surveillance and risk mitigation of rodent reservoirs at zoos.

SARS-CoV-2 infection, neuropathogenesis and transmission among deer mice: Implications for spillback to New World rodents.

Coronavirus disease-19 (COVID-19) emerged in late 2019 in China and rapidly became pandemic. As with other coronaviruses, a preponderance of evidence suggests the virus originated in horseshoe bats (Rhinolophus spp.) and may have infected an intermediate host prior to spillover into humans. A significant concern is that SARS-CoV-2 could become established in secondary reservoir hosts outside of Asia. To assess this potential, we challenged deer mice (Peromyscus maniculatus) with SARS-CoV-2 and found robust virus replication in the upper respiratory tract, lungs and intestines, with detectable viral RNA for up to 21 days in oral swabs and 6 days in lungs. Virus entry into the brain also occurred, likely via gustatory-olfactory-trigeminal pathway with eventual compromise to the blood-brain barrier. Despite this, no conspicuous signs of disease were observed, and no deer mice succumbed to infection. Expression of several innate immune response genes were elevated in the lungs, including IFNα, IFNß, Cxcl10, Oas2, Tbk1 and Pycard. Elevated CD4 and CD8ß expression in the lungs was concomitant with Tbx21, IFNγ and IL-21 expression, suggesting a type I inflammatory immune response. Contact transmission occurred from infected to naive deer mice through two passages, showing sustained natural transmission and localization into the olfactory bulb, recapitulating human neuropathology. In the second deer mouse passage, an insertion of 4 amino acids occurred to fixation in the N-terminal domain of the spike protein that is predicted to form a solvent-accessible loop. Subsequent examination of the source virus from BEI Resources determined the mutation was present at very low levels, demonstrating potent purifying selection for the insert during in vivo passage. Collectively, this work has determined that deer mice are a suitable animal model for the study of SARS-CoV-2 respiratory disease and neuropathogenesis, and that they have the potential to serve as secondary reservoir hosts in North America.

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.

Vector Specificity of the Relapsing Fever Spirochete Borrelia hermsii (Spirochaetales: Borreliaceae) for the Tick Ornithodoros hermsi (Acari: Argasidae) Involves Persistent Infection of the Salivary Glands.

The relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae are each maintained and transmitted in nature by their specific tick vectors, Ornithodoros hermsi Wheeler (Acari: Argasidae) and Ornithodoros turicata (Duges), respectively. The basis for this spirochete and vector specificity is not known, but persistent colonization of spirochetes in the tick's salivary glands is presumed to be essential for transmission by these long-lived ticks that feed in only minutes on their warm-blooded hosts. To examine this hypothesis further, cohorts of O. hermsi and O. turicata were infected with B. hermsii and examined 7-260 d later for infection in their midgut, salivary glands, and synganglion. While the midgut from all ticks of both species at all time points examined were infected with spirochetes, the salivary glands of only O. hermsi remained persistently infected. The salivary glands of O. turicata were susceptible to an early transient infection. However, no spirochetes were observed in these tissues beyond the first 32 d after acquisition. Ticks of both species were fed on mice 112 d after they acquired spirochetes and only those mice fed upon by O. hermsi became infected. Thus, the vector competency for B. hermsii displayed by O. hermsi but not O. turicata lies, in part, in the persistent infection of the salivary glands of the former but not the latter species of tick. The genetic and biochemical mechanisms supporting this spirochete and vector specificity remain to be identified.

HOST-SWITCHING EVENTS IN LITOMOSOIDES CHANDLER, 1931 (FILARIOIDEA: ONCHOCERCIDAE) ARE NOT RAMPANT BUT CLADE DEPENDENT.

The genus Litomosoides Chandler, 1931, includes species that as adults occur in the thoracic and abdominal cavity of mammalian hosts and are presumably vectored by mites. The vertebrate hosts include a variety of Neotropical mammals such as phyllostomid and mormoopid bats; cricetid, sciurid, and hystricognath rodents; and didelphid marsupials. It has been suggested that Litomosoides is not a monophyletic group and that rampant horizontal transfer explains their presence in disparate groups of mammals. Herein we present a phylogenetic reconstruction including mitochondrial genes of 13 vouchered species. This phylogeny is used to reconstruct the evolutionary history of these parasites and the ancestral states of key characters used in species classification, namely, the configuration of the spicules. The historical association of these filarioids with 6 groups of mammals, as well as their ancestral geographic distributions, were reconstructed using Bayesian statistical approaches comparing alternative models of biogeography and evolution and fossil states in selected nodes of the phylogeny. The optimal reconstruction suggests a model of dispersal, extinction, and cladogenesis (DEC) driving the evolution of Litomosoides; the results suggest an origin of Litomosoides in South America and association of ancestors with phyllostomids, and strong evidence of at least 2 host-switching events: 1 of these involving cricetid rodents and the other mormoopid bats. The latter event included a simultaneous geographic expansion of the parasite lineage across South and North America. The host-switching event from phyllostomid bats into cricetid rodents occurred once these rodents diversified across South America; subsequent diversification of the latter clade resulted in 2 branches, each showing expansion of the parasites back into North America. This result suggests that both parasites and cricetid rodents established an association in South America, underwent diversification, and then dispersed into North America. Further, this clade of cricetid-dwelling species includes parasites featuring the "sigmodontis" spicule type. The identification of a single host-switching event involving the disparate lineages of Chiroptera and Rodentia offers a framework to reconstruct the gene evolution and diversification of this lineage after the host-switching event. This will help in predicting the ability of these parasites to infect sympatric mammals.

Experimental SARS-CoV-2 Infection of Bank Voles.

After experimental inoculation, severe acute respiratory syndrome coronavirus 2 infection was confirmed in bank voles by seroconversion within 8 days and detection of viral RNA in nasal tissue for up to 21 days. However, transmission to contact animals was not detected. Thus, bank voles are unlikely to establish effective transmission cycles in nature.

Evaluation of In-cage Filter Paper as a Replacement for Sentinel Mice in the Detection of Murine Pathogens.

Recent studies have evaluated alternatives to the use of live animals in colony health monitoring. Currently, an alternative method that is suitable for all rack types and that has been verified to detect the infectious agents most commonly excluded from mouse colonies is unavailable. We compared the use of filter paper placed on the inside floor of mouse cages to the traditional use of sentinel mice in the detection of several prevalent murine pathogens including mouse hepatitis virus (MHV), murine norovirus (MNV), minute virus of mice (MVM), mouse parvovirus (MPV), Theiler murine encephalomyelitis virus (TMEV), Helicobacter spp., Syphacia obvelata, and Aspiculuris tetraptera. Experimental groups comprised 7 cages containing either 2 pieces of filter paper on the cage floor or 2 ICR sentinel mice. Soiled bedding from pet-store mice was transferred to the experimental cages weekly for 8 wk. At 1 and 2 mo after bedding transfer, the filter papers were evaluated by PCR and sentinel mice were tested by serology and fecal PCR. Filter papers detected all pathogens as effectively (MHV, MNV, MPV, MVM, TMEV S. obvelata, and A. tetraptera) or more effectively (Helicobacter spp.) than sentinel mice at both time points. Filter papers more readily detected pathogens with a high copy number per RT-PCR analysis than a low copy number. Helicobacter spp. were not detected by sentinel mice at either time point. These results indicate that the use of filter paper placed on the interior floor of empty mouse cages and exposed to soiled bedding is efficient in detecting bacteria, endoparasites, and most of the common mouse viruses included in an animal health monitoring program.

Ectoparasitic community of the Mahali mole-rat, Cryptomys hottentotus mahali: potential host for vectors of medical importance in South Africa.

BACKGROUND: The endemic rodent family of Bathyergidae in Africa, particularly South Africa, are understudied as reservoirs of diseases of significant medical importance. Considering the diversity and wide distribution of African mole-rats in South Africa, many of these bathyergids could act as carriers of zoonoses. METHODS: The present study assessed the ectoparasite community of the Mahali mole-rat (Cryptomys hottentotus mahali). We aimed to identify possible parasitic arthropods that may infest this mole-rat species and explore host preference, contributions of seasonality, host sex and body mass as well as social class and colony size on ectoparasite assemblage prevalence and abundance. RESULTS: A limited number of ectoparasite species were found on C. h. mahali belonging to two significant taxa: mites (Acari) and fleas, with mites being the most prevalent and abundant. We recorded the presence of X. philoxera, a flea well known as the principal reservoir of plague in the southern African region on the Mahali mole-rats. Only three mite species were collected: Androlaelaps scapularis, Androlaelaps capensis and Laelaps liberiensis. Seasonal peaks in prevalence and abundance of X. philoxera and A. scapularis were observed during summer. Xenopsylla philoxera abundance and A. scapularis loads significantly increased on reproductive mole-rat individuals in comparison to non-reproductive individuals. CONCLUSION: Despite the wide distribution of the subterranean African mole-rats, studies investigating their parasitic fauna remain limited and scarce. This dearth in knowledge raises the concern regarding their potential role as an endemic reservoir for zoonotic diseases. Consequently, additional sampling of their ectoparasitic community throughout their distributional range and research addressing their role as a reservoir for zoonotic diseases in southern Africa are urgently needed.

Alternative pathways in Angiostrongylus cantonensis (Metastrongyloidea: Angiostrongylidae) transmission.

In order to elucidate the infection pathways of third stage larvae (L3) of Angiostrongylus cantonensis, we performed experiments to assess: (i) the shedding of L3 from two species of experimental veronicellid slugs drowned in water and the ratio of emerged larvae, (ii) the transmission of viable L3 from drowned terrestrial gastropods to aquatic snails, and (iii) the transmission of viable L3 between terrestrial snails. Molluscs were experimentally infected by first stage larvae (L1) of A. cantonensis. Significantly more L3 larvae were released from Veronicella cubensis than from Veronicella sloanei. Numerous L3 were observed in the muscular foot, and also in the connective tissue between internal organs. Experimental exposure of P. maculata to L3 of A. cantonensis liberated from other gastropod species led to their infection and the infectivity of larvae after intermediesis was demonstrated by infection of laboratory rats (Rattus norvegicus). The transmission of L3 was observed in three out of four experiment replications and L3 were retrieved from 6 out of 24 Subulina octona snails. The infected synanthropic molluscs represent a key component in the epidemiology of human infections by A. cantonensis. Escape of L3 larvae from bodies of dead snails or slugs and their ability to infect further gastropod hosts (intermediesis) represents a public health risk. Thus, control of molluscs living in peri-domestic environment is an essential part of prevention of human infections.

Transmission networks and ectoparasite mite burdens in Oecomys paricola (Rodentia: Cricetidae).

The host contact network structure results from the movement and behaviour of hosts (e.g. degree of sociability; vagility and greater or lesser fidelity of shelters), which can generate heterogeneity in the transmission of parasites and influence the parasitic burden of individual hosts. In the current study, we tested the hypothesis that the burdens of Gigantolaelaps oudemansi mites are related to the characteristics of the transmission networks of individuals of Oecomys paricola, a solitary rodent. The study was carried out in a savannah habitat in north-eastern Brazil. In the dry season, the rodent network presented sub-groups of rodent individuals interacting with each other, whereas in the wet season, no modules were formed in the network. Mite burden was positively related to the number of connections that an individual host had with other host individuals in the dry season. The pairwise absolute difference between the mean mite burdens among individual rodents was negatively correlated with the similarities of node interactions. No relationships were observed during the wet season. There was a higher heterogeneity of mite burden among hosts in the dry season compare to that in the wet season. In solitary species, spatial organization may show seasonal variation, causing a change in the opportunities of host contacts, thereby influencing the transmission and dispersion of their ectoparasite burdens.