Cross-species transmission of Cryptosporidium in wild rodents from the southern region of Zhejiang Province of China and its possible impact on public health.

Wild rodents serve as reservoirs for Cryptosporidium and are overpopulated globally. However, genetic data regarding Cryptosporidium in these animals from China are limited. Here, we have determined the prevalence and genetic characteristics of Cryptosporidium among 370 wild rodents captured from three distinct locations in the southern region of Zhejiang Province, China. Fresh feces were collected from the rectum of each rodent, and DNA was extracted from them. The rodent species was identified by PCR amplifying the vertebrate cytochrome b gene. Cryptosporidium was detected by PCR amplification and amplicon sequencing the small subunit of ribosomal RNA gene. Positive samples of C. viatorum and C. parvum were further subtyped by analyzing the 60-kDa glycoprotein gene. A positive Cryptosporidium result was found in 7% (26/370) of samples, involving five rodent species: Apodemus agrarius (36), Niviventer niviventer (75), Rattus losea (18), R. norvegicus (155), and R. tanezumi (86). Their respective Cryptosporidium positive rates were 8.3%, 5.3%, 11.1%, 7.1%, and 7.0%. Sequence analysis confirmed the presence of three Cryptosporidium species: C. parvum (4), C. viatorum (1), and C. muris (1), and two genotypes: Cryptosporidium rat genotype IV (16) and C. mortiferum-like (4). Additionally, two subtypes of C. parvum (IIdA15G1 and IIpA19) and one subtype of C. viatorum (XVdA3) were detected. These results demonstrate that various wild rodent species in Zhejiang were concurrently infected with rodent-adapted and zoonotic species/genotypes of Cryptosporidium, indicating that these rodents can play a role in maintaining and dispersing this parasite into the environment and other hosts, including humans.

Title: Transmission interspécifique de Cryptosporidium chez les rongeurs sauvages de la région sud de la province chinoise du Zhejiang et son impact possible sur la santé publique. Abstract: Les rongeurs sauvages servent de réservoirs à Cryptosporidium et ont des grandes populations à l'échelle mondiale. Cependant, les données génétiques concernant Cryptosporidium chez ces animaux en Chine sont limitées. Ici, nous avons déterminé la prévalence et les caractéristiques génétiques de Cryptosporidium parmi 370 rongeurs sauvages capturés dans trois endroits distincts de la région sud de la province du Zhejiang, en Chine. Des excréments frais ont été collectés dans le rectum de chaque rongeur et l'ADN en a été extrait. L'espèce de rongeur a été identifiée par amplification par PCR du gène du cytochrome b des vertébrés. Cryptosporidium a été détecté par amplification PCR et séquençage d'amplicons de la petite sous-unité du gène de l'ARN ribosomal. Les échantillons positifs de C. viatorum et C. parvum ont ensuite été sous-typés en analysant le gène de la glycoprotéine de 60 kDa. Un résultat positif pour Cryptosporidium a été trouvé dans 7 % (26/370) des échantillons, impliquant cinq espèces de rongeurs : Apodemus agrarius (36), Niviventer niviventer (75), Rattus losea (18), R. norvegicus (155) et R. tanezumi (86). Leurs taux respectifs de positivité pour Cryptosporidium étaient de 8,3 %, 5,3 %, 11,1 %, 7,1 % et 7,0 %. L'analyse des séquences a confirmé la présence de trois espèces de Cryptosporidium : C. parvum (4), C. viatorum (1) et C. muris (1), et de deux génotypes : Cryptosporidium génotype IV de rat (16) et C. mortiferum-like (4). De plus, deux sous-types de C. parvum (IIdA15G1 et IIpA19) et un sous-type de C. viatorum (XVdA3) ont été détectés. Ces résultats démontrent que diverses espèces de rongeurs sauvages du Zhejiang sont simultanément infectées par des espèces/génotypes de Cryptosporidium zoonotiques et adaptés aux rongeurs, ce qui indique que ces rongeurs peuvent jouer un rôle dans le maintien et la dispersion de ce parasite dans l'environnement et d'autres hôtes, y compris les humains.

Reservoir displacement by an invasive rodent reduces Lassa virus zoonotic spillover risk.

The black rat (Rattus rattus) is a globally invasive species that has been widely introduced across Africa. Within its invasive range in West Africa, R. rattus may compete with the native rodent Mastomys natalensis, the primary reservoir host of Lassa virus, a zoonotic pathogen that kills thousands annually. Here, we use rodent trapping data from Sierra Leone and Guinea to show that R. rattus presence reduces M. natalensis density within the human dwellings where Lassa virus exposure is most likely to occur. Further, we integrate infection data from M. natalensis to demonstrate that Lassa virus zoonotic spillover risk is lower at sites with R. rattus. While non-native species can have numerous negative effects on ecosystems, our results suggest that R. rattus invasion has the indirect benefit of decreasing zoonotic spillover of an endemic pathogen, with important implications for invasive species control across West Africa.

Immune interactions and heterogeneity in transmission drives the pathogen-mediated invasion of grey squirrels in the UK.

Mathematical models highlighted the importance of pathogen-mediated invasion, with the replacement of red squirrels by squirrelpox virus (SQPV) carrying grey squirrels in the UK, a well-known example. In this study, we combine new epidemiological models, with a range of infection characteristics, with recent longitudinal field and experimental studies on the SQPV dynamics in red and grey squirrel populations to better infer the mechanistic basis of the disease interaction. A key finding is that a model with either partial immunity or waning immunity and reinfection, where individuals become seropositive on the second exposure to infection, that up to now has been shown in experimental data only, can capture the key aspects of the field study observations. By fitting to SQPV epidemic observations in isolated red squirrel populations, we can infer that SQPV transmission between red squirrels is significantly (4×) higher than the transmission between grey squirrels and as a result our model shows that disease-mediated replacement of red squirrels by greys is considerably more rapid than replacement in the absence of SQPV. Our findings recover the key results of the previous model studies, which highlights the value of simple strategic models that are appropriate when there are limited data, but also emphasise the likely complexity of immune interactions in wildlife disease and how models can help infer disease processes from field data.

Serological survey of hantavirus in rodents in Uberlândia, Minas Gerais, Brazil / Inquérito sorológico de hantavírus em roedores, Uberlândia, Minas Gerais, Brasil

We conducted a serological survey to determine the presence of hantavirus infection in rodents in Uberlândia, Minas Gerais as well as to identify and characterize associated factors. Rodents were captured using Sherman live-capture traps set in rural and peri-urban environments. A total of 611 rodents were captured. There was a higher trap success in peri-urban areas (26.3%) and a higher prevalence of antibodies among rodents captured in rural areas (2.9%). Necromys lasiurus was the most common species (42.2%) and the more frequently infected (4.6%). One Calomys tener (1/141; 0.7%) and one Calomys sp. (1/14; 7.1%) were also positive for the hantavirus infection. In N. lasiurus, antibody prevalence correlated with population density (p < 0.01), age class (p = 0.003) and presence of scars (p = 0.02). The data confirm that horizontal transmission is the main mechanism that maintains the virus in nature. The higher seropositivity in N. lasiurus is consistent with genetic studies that associate this species with an Araraquara virus reservoir; the seropositivity of C. tener and Calomys sp. may indicate the occurrence of spillover infection or the presence of other circulating hantaviruses.

Realizamos um estudo transversal para identificar a presença de infecção por hantavírus em roedores em Uberlândia, Minas Gerais, e também para identificar e caracterizar fatores associados. Roedores foram capturados usando armadilhas do tipo Sherman em ambientes rural e periurbano. Um total de 611 roedores foi capturado. Houve maior sucesso de captura na área periurbana (26,3%) e maior prevalência de anticorpos entre os roedores capturados na área rural (2,9%). Necromys lasiurus foi a espécie mais encontrada (42,2%) e a mais frequentemente infectada (4,6%). Um Calomys tener (1/141; 0.7%) e um Calomys sp. (1/14; 7.1%) foram também positivos. Os dados obtidos mostram que em N. lasiurus, a prevalência de anticorpos está relacionada à densidade populacional (p < 0.01), a classe de idade (p = 0.003) e a presença de cicatrizes (p = 0.02), confirmando que a transmissão horizontal é o principal mecanismo que mantém o vírus na natureza. A maior positividade em N. lasiurus é consistente com estudos genéticos que permitem associar esta espécie como reservatório do vírus Araraquara; a soropositividade de C. tener e Calomys sp. pode indicar a ocorrência de "spillover infection" ou a presença de outros hantavírus circulantes.

Aspectos serológicos, clínicos y epidemiológicos de un brote de triquinosis en Azul, Provincia de Buenos Aires / Serological, clinical and epidemiological aspects of an outbreak of trichinosis in Azul, province of Buenos Aires

Se estudió un brote de triquinosis ocurrido en el sur de la provincia de Buenos Aires, zona endémica para esta zoonosis. Dieciocho personas fueron afectadas por la ingesta de productos elaborados con carne de cerdo (chacinados sin el correspondiente control veterinario. Se describen síntomas y signos de los apcientes, como así también estudios serológicos relacionados con la formación de anticuerpos y la capacidad citotóxica de los sueros. Se analizaron los producto elaborados (chacinados), así como ocho cerdos interdictos de la granja donde se originó el brote. Con el fin de estudiar la cadena de transmisión se capturaron y analizaron ratas de los alrededores del hábitar de los porcinos. Este trabajo demuestra que los principales síntomas y signos fueron: mialgia, edema palpebral, fiebre y cefalea, que el 61// de los pacientes presentó anticuerpos contra el estadio de larva muscular entre los 15-30 días posteriores a la ingesta, que sólo presentaron anticuerpos contra la larva recien nacida a los 40-60 días postinfección cinco de los dieciocho pacientes, que la carga parasitaria en los chacinados fue de 5,3 larvas/g, que dos de los ocho cerdos se diagnosticaron por técnicas serológicas, mientras que por técnicas parasitológicas se detectó sólo uno y que la rata es uno de los principales reservorios en la cadena epidemiológica

Rabies in the State of Säo Paulo: the rodents question

Compulsaram-se dados epidemiológicos a respeito de agressäo por roedores no período de 1976 a 1985, nos registros do Instituto Pasteur de Säo Paulo (Brasil). Observou-se que de 367 379 pessoas agredidas, 22 250 foram vítimas de roedores. Os roedores mais implicados nesses acidentes foram os urbanos, sendo que a captura foi um fator limitante para o envio de amostras ao laboratório. O diagnóstico laboratorial realizado em 1083 amostras de roedores näo revelou nenhum caso positivo no período, embora a raiva estivesse presente em outras espécies animais. Conclui-se que, sendo a raiva rara entre os roedores, é necessário que se realizem provas de identificaçäo do vírus quando houver suspeita de caso positivo; e que, näo existindo casos relatados de óbitos humanos por raiva relacionados a roedores, existe a possibilidade de reduçäo dos tratamentos anti-rábico pós-exposiçäo a estes animais