Spatial analysis on the occurrence of Pneumocystis carinii in the shrew Notiosorex crawfordi in fragmented landscape in southern California.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
J Laakkonen
Publications and source records attributed to J Laakkonen.
Haemogregarines of the genus Hepatozoon (Apicomplexa: Adeleina) in rodents from northern Europe.
We studied the prevalence and distribution of Hepatozoon infections in small rodents from Finland and other areas in northern Europe. Hepatozoon infections were more common in voles (Arvicolinae) than mice (Murinae) and more prevalent in voles of the genus Clethrionomys than in voles of the genus Microtus. Transmission electron microscopical examination of Hepatozoon erhardovae Krampitz, 1964 from bank voles Clethrionomys glareolus (Schreber) showed that intracellular lung meronts were located in alveolar septa. Meronts consisted of varying numbers of merozoites packed with amylopectin vacuoles inside electron-lucent parasitophorous vacuole. The size of the meronts was approximately 19 x 14 microm. Monozoic or dizoic cysts were frequent findings in the lung alveoles; the size of cysts was approximately 10 x 6 microm. Gametocytes were found inside eosinophilic granulocytes in the capillaries of lung tissue. Ultrastructurally, micronemes, microtubules, mitochondria, nuclei and lipid droplets were visible.
Animals↗
Pneumocystosis in wild small mammals from California.
Cyst forms of the opportunistic fungal parasite Pneumocystis carinii were found in the lungs of 34% of the desert shrew, Notiosorex crawfordi (n = 59), 13% of the ornate shrew, Sorex ornatus (n = 55), 6% of the dusky-footed wood rat, Neotoma fuscipes (n = 16), 2.5% of the California meadow vole, Microtus californicus (n = 40), and 50% of the California pocket mouse, Chaetodipus californicus (n = 2) caught from southern California between February 1998 and February 2000. Cysts were not found in any of the harvest mouse, Reithrodontomys megalotis (n = 21), California mouse, Peromyscus californicus (n = 20), brush mouse, Peromyscus boylii (n = 7) or deer mouse, Peromyscus maniculatus (n = 4) examined. All infections were mild; extrapulmonary infections were not observed. Other lung parasites detected were Hepatozoon sp./spp. from M. californicus and Notiosorex crawfordi, Chrysosporium sp. (Emmonsia) from M. californicus, and a nematode from S. ornatus.
Animal Diseases↗
Disease patterns in field and bank vole populations during a cyclic decline in central Finland.
Declining field vole (Microtus agrestis) and bank vole (Clethrionomys glareolus) populations were sampled (117 field voles and 34 bank voles) in south-central Finland during the winter of 1988-89. The last surviving field voles were caught in April and bank voles in February. A subsample (16) of the April field voles were taken live to the laboratory for immunosuppression. The histopathology of the main internal organs and the presence of aerobic bacteria and certain parasites were studied. In the lungs, an increase in lymphoid tissue, probably caused by infections, was the most common finding (52% of all individuals). The prevalences in the voles, in the whole material, of Chrysosporium sp. and Pneumocystis carinii in lungs were 13 and 10% in field voles, and 9 and 0% in bank voles, respectively. Cysts of Taenia mustelae (9 and 27%) were the most common pathological changes in the liver. Enteritis was also rather common (14 and 34%). In field voles the prevalences of Frenkelia sp. in the brain and Sarcocystis sp. in leg muscles were low (both 6%). Bordetella bronchiseptica was commonly (31%) isolated from field vole lungs and Listeria monocytogenes from the intestines (34%). Salmonella spp. could not be found. The dynamics and abundance of inflammations in the lungs and intestines, as well as B. bronchiseptica isolations from the lungs, indicate that obvious epidemics took place in declining vole populations. Of the Luhanka subsample of 16 field voles brought to the laboratory in April, one died of listeriosis, two of Bordetella, and five died for unknown reasons. Even if small mustelids are the driving force in microtine cycles, it is possible that diseases also contribute to the decline.
Animals↗
Molecular evolution of puumala hantavirus in Fennoscandia: phylogenetic analysis of strains from two recolonization routes, Karelia and Denmark.
Like other members of the genus HANTAVIRUS: in the family BUNYAVIRIDAE:, Puumala virus (PUUV) is thought to be co-evolving with its natural host, the bank vole Clethrionomys glareolus. To gain insight into the evolutionary history of PUUV in northern Europe during the last post-glacial period, we have studied wild-type PUUV strains originating from areas along two postulated immigration routes of bank voles to Fennoscandia. Full-length sequences of the S RNA segment and partial sequences (nt 2168-2569) of the M segment were recovered by RT-PCR directly from bank vole tissues collected at three locations in Russian Karelia and one location in Denmark. Phylogenetic analysis showed that strains from Karelia and Finland belong to the same genetic lineage, supporting the hypothesis that PUUV spread to present Finland via a Karelian land-bridge. The Danish PUUV strains showed no particularly close relatedness to any of the known PUUV strains and formed a distinct phylogenetic lineage on trees calculated for both S and M segment sequences. Although no direct link between the Danish PUUV strains and those of the southern Scandinavian lineage was found, within the S segment of Danish PUUV strains, two regions with higher similarity to either northern Scandinavian or - to a less extent - southern Scandinavian genetic lineages were revealed, suggesting evolutionary connections of their precursors.
Amino Acid Sequence↗
Ultrastructure of Frenkelia sp. from a Norwegian lemming in Finland.
An apparently healthy Norwegian lemming (Lemmus lemmus) caught in northern Finland was observed to have a whitish body 0.5 to 1.0 mm in diameter in the external layer of the cerebral cortex. By light microscopy a highly lobulated cyst of Frenkelia sp. was observed. By transmission electron microscopy lemmus) collected in the cyst wall was seen consisting of a parasitophorous vacuolar membrane, an underlying electron-dense layer and a granular layer. The membrane was only slightly convoluted. The protrusions of the cyst wall appeared round but were often not distinctive. A very thin septum divided the interior of the cyst into compartments packed with bradyzoites and maturing zoites. The bradyzoites were elongate measuring 5-8 x 1.5-2 microm. This is the first electron microscopical study of Frenkelia sp. from L. lemmus.
Animals↗
The ecological impact of fungal infections on wildlife populations.
Explore the source record for details and available documents.
Animals↗
Seasonal dynamics of Pneumocystis carinii in the field vole, Microtus agrestis, and in the common shrew, Sorex araneus, in Finland.
Seasonal dynamics of Pneumocystis carinii in the field vole, Microtus agrestis, and in the common shrew, Sorex araneus, were investigated in southern and central Finland by microscopical examination of methenamine silver-stained tissue sections. In both host species at both localities the number of P. carinii cyst forms was highest in late autumn (November). In S. araneus, prevalence was higher than in M. agrestis during all seasons. None of the animals was heavily infected or apparently ill, and neither species showed any extrapulmonary dissemination. In this study covering an increase phase and 4 peak host-density phases of the vole cycle, the occurrence of P. carinii seemed to be related to the population density of M. agrestis.
Animals↗
Isolation and characterization of Dobrava hantavirus carried by the striped field mouse (Apodemus agrarius) in Estonia.
Dobrava hantavirus (DOB) was isolated from the striped field mouse (Apodemus agrarius) trapped on Saaremaa Island, Estonia, and its genetic and antigenic characteristics were subsequently analysed. Phylogenetic analysis showed that the Estonian DOB strain, together with several wild strains carried by Apodemus agrarius, forms a well-supported lineage within the DOB clade. The topography of the trees calculated for the S, M and L nucleotide sequences of the Estonian DOB suggests a similar evolutionary history for all three genes of this virus and, therefore, the absence of heterologous reassortment in its evolution. A cross-neutralization comparison of the Estonian virus with the prototype DOB, isolated from a yellow-necked mouse (A. flavicollis) in Slovenia, revealed 2- to 4-fold differences in the end-point titres of rabbit and human antisera. When studied with a panel of 25 monoclonal antibodies (MAbs), the Estonian and Slovenian DOB isolates showed similar antigenic patterns that could be distinguished by two MAbs. Genetic comparison showed sequence differences in all three genome segments of the two DOB isolates, including an additional N-glycosylation site in the deduced sequence of the G2 protein from the Estonian virus. Whether any of these mutations relates to the different rodent hosts rather than to the distant geographical origin of the two isolates remains to be resolved. Taken together, our observations suggest that A. agrarius, which is known to harbour Hantaan virus in Asia, carries another hantavirus, DOB, in north-east Europe.
Animals↗
Pneumocystis carinii in wildlife.
Pneumocystis carinii is a eukaryotic organism capable of causing life-threatening pneumonia (PCP) in immunocompromised hosts. Despite intensive investigation in human and laboratory animal hosts, information on the occurrence and nature of infections in wild animals is scarce, although characterisation of infections in wild-animal populations may help to elucidate the life-cycle and transmission of this elusive organism. Due to the interspecific differences in prevalence and intensity of P. carinii infection, and to the antigenic and genetic diversity of P. carinii organisms originating from various host species, which may affect the infectivity and pathogenicity of these organisms, we should be cautious when making generalisations about the nature of P. carinii infection. This review summarises the present state of knowledge on the occurrence of P. carinii in wild mammals in their natural habitats, and briefly discusses various characteristics of P. carinii infection important for understanding the distribution and abundance of this organism. Some aspects of P. carinii infection in wild hosts of particular interest for future research in this field will also be discussed.
Animals↗
Lung parasites of least weasels in Finland.
Because of their constant exposure to normal rodent definitive hosts, least weasels (Mustela nivalis) were trapped in southern Finland in late fall 1994 and examined for lung parasites. Histological examination showed that 46% of the weasels (n = 46) were infected with adiaspores identified as Chrysosporium sp. Granulomas surrounding the adiaspores consisted of mostly unorganized layers of mononuclear cells. The adiaspores from least weasels were much smaller than those reported from their prey animals. Infection with Pneumocystis carinii also was found in two weasels.
Animals↗
Blood parasites of shrews from Pennsylvania.
We examined 30 Sorex cinereus, 5 Sorex fumeus, and 21 Blarina brevicauda collected from Pennsylvania in 1995 for blood parasites. Trypomastigotes of Trypanosoma sp. were visible in 13% of the S. cinereus. Ten percent of S. cinereus, 20% of S. fumeus, and 14% of B. brevicauda were infected with Bartonella sp. (or spp.). In S. cinereus, we detected no concurrent Trypanosoma and Bartonella infections.
Animals↗
Lung parasites of shrews from Pennsylvania.
We examined lung parasites of three species of soricids, Sorex cinereus (n = 58), Sorex fumeus (n = 23) and Blarina brevicauda (n = 45) collected from Pennsylvania (USA), from 1990 to 1995. Yeast-like cells of Hisfoplasma capsulatum var. capsulatum were found in lung sections stained with Grocott's modification of Gomori's methenamine silver, periodic acid-Schiff, Giemsa, and hematoxylin-eosin in two (3%) S. cinereus, eight (35%) S. fumeus and two (4%) B. brevicauda. The number of spores of H. capsulatum in the lungs was low and no inflammatory reaction was evident. The infection was not disseminated to other organs. This is the first report of H. capsulatum infection in any species of shrews of the genus Sorex and the prevalence in S. fumeus was remarkably high compared to those reported for other wild mammals. A nematode, possibly Angiostrongylus michiganensis, was found in the lungs of one S. fumeus on necropsy and in a stained lung section of one S. cinereus. In both cases the host was also infected with the fungus. Pneumocystis carinii, which is the most common lung parasite in Sorex araneus (the numerically dominant Eurasian species of shrew), was not found in any of the North American species of shrew examined in this study.
Angiostrongylus↗
Occurrence of Pneumocystis carinii in canine distemper.
Explore the source record for details and available documents.
Animals↗
Genetic variation of wild Puumala viruses within the serotype, local rodent populations and individual animal.
Reverse transcriptase polymerase chain reaction cloning and sequencing were used to determine the range of S gene/N protein variability in wild Puumala virus (PUU) strains and to study phylogenetic relationships between two groups of strains which originated from Finland and from European Russia. Analyses of the nucleotide and predicted amino acid sequences showed: (1) all PUU strains shared a common ancient ancestor; and (2) the more recent ancestors were different for the Finnish branch and the Russian branch of PUU strains. A cluster of amino acid substitutions in the N protein of Finnish strains was found; this cluster was located within a highly variable region of the molecule carrying B-cell epitopes (Vapalahti et al., J. Med. Virol., 1995, in press). Different levels of S gene/N protein diversity of PUU were revealed supporting the view of geographical clustering of genetic variants. Puumala virus from individual voles was found to be a complex mixture of closely related variants-quasispecies. The ratio of non-silent to silent nucleotide mutations registered in the S genes/N proteins of PUU quasispecies was 4- to 16-fold higher than that in Puumala virus strains, resulting in a more wide range of quasispecies N protein sequence diversity.
Amino Acid Sequence↗
Characterization of Pneumocystis carinii infection in Sorex araneus from southern Finland.
Histologic and quantitative techniques were compared in an evaluation of the intensity of Pneumocystis carinii infection in common shrews (Sorex araneus) at Espoo, southern Finland, from September 1992 to May 1993. The histological scores were comparable to the results of the cyst count technique. The number of P. carinii cysts found in common shrews was low compared to those reported by others in clinically ill laboratory rats. The inflammatory changes detected in the lung sections had no significant relation to the presence of P. carinii infection.
Age Distribution↗
Prevalence of Cryptosporidium sp. in peak density Microtus agrestis, Microtus oeconomus and Clethrionomys glareolus populations.
The prevalence of cryptosporidia was determined in high density populations of Microtus agrestis, Microtus oeconomus, and Clethrionomys glareolus in Finland. One of 131 M. Agrestis and one of 41 C. glareolus each were found to be infected with Cryptosporidium sp.; none were found in 43 Microtus oeconomus. These apparently healthy voles had neither signs of clinical disease nor histopathological changes in intestines.
Animals↗