Comparison of two surgical approaches for the treatment of primary spontaneous pneumothorax*.

AIM: The authors report a retrospective study on surgical treatment of primary spontaneous pneumothorax (PSP). Surgical approaches by Videoassisted axillary mini-thoracothomy (VAMT) and three-port VATS (t-VATS) are compared. Mean post-operative stay (MPS) and ipsilateral recurrence rate (IRR) are assessed. Secondary endpoints were about complications, early post-operative pain and long term neurologic symptoms. PATIENTS AND METHODS: From January 2009 to December 2011 we consecutively observed 85 cases of PSP. Treatment was represented by surgery in 52 patients: the approach was by VAMT in 39 instances and t-VATS in 13. Median follow up was 30 months. RESULTS: Patients submitted to surgery had a MPS of 6.62 ± 1.5 days for VAMT and 6.69 ± 3.4 days for t-VATS (p=0,94). The IRR was 0% in both surgical approaches, comparing to 7,2% for the group of patients treated by simple drainage. Complications were observed in VAMT group: 2 conversions to thoracothomy for technical difficulties (extensive pleural adherences) and one case of re-thoracothomy for hemothorax. Mean Visual Analogic Scale (VAS) score for early post-operative pain was: 2.10±0.71 for VAMT and 1.92±0.64 for t-VATS, p=0.42 at t-student test. Paresthesia complain rate was 33.3% (VAMT) vs 30.7% (t-VATS) for moderate symptoms (p=0.72 at chi square test). The remaining patients complained only slight symptoms or no symptoms at all. CONCLUSIONS: Our experience suggested that both surgical approaches to PSP are safe and effective. No differences were found for early post-operative pain and long term paresthesia rate, between the two approaches. No recurrence occurred during follow up.

Presence of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) in southern Kettle Moraine State Forest, Wisconsin, and characterization of strain W97F51.

Lyme disease, caused by Borrelia burgdorferi Johnson, Schmidt, Hyde, Steigerwalt & Brenner; babesiosis, caused by Babesia microti Franca; and human granulocytic ehrlichiosis, caused by Anaplasma phagocytophilum Bakken & Dumler have been reported in Wisconsin, mainly in the endemic areas of the northwestern part of the state. People exposed to blacklegged ticks, Ixodes scapularis Say, from this region can potentially contract one or all of these diseases concurrently. Within the past several years, there have been cases of Lyme disease reported from southeastern Wisconsin, an area that contains deer, mice, and similar vegetation found at regions with high endemicity. However, past white-tailed deer surveys suggested no existence of I. scapularis in southeastern Wisconsin. However, in 1996, we identified questing adult I. scapularis in the southernmost part of the Southern Kettle Moraine State Forest, Walworth County. To determine whether an established population of I. scapularis exists in this region, we performed a detailed survey of the abundance of host-seeking I. scapularis adults and the presence and abundance of subadults feeding on white-footed mice, Peromyscus leucopus Rafinesque. We also tested for possible infections of B. burgdorferi, Ba. microti, and A. phagocytophilum in ticks and B. burgdorferi harbored by mice. In 1997 and 1998, a total of 249 P. leucopus mice and 118 questing adult I. scapularis ticks, in addition to 157 larvae and seven nymphs feeding on mice, were collected and their locations were recorded from the Nordic trails of the Southern Kettle Moraine State Forest. Only one P. leucopus and its attached engorged I. scapularis nymph were infected with B. burgdorferi, whereas none of the engorged larvae attached to mice were infected. However, 4.2% of questing adult I. scapularis were infected with B. burgdorferi. The abundance of questing adult I. scapularis was 1.6 ticks per hour. The prevalence of subadult ticks on mice was 27%, with a mean intensity on infested mice of 2.0. I. scapularis adults were not infected with either Ba. microti or A. phagocytophilum. A unique strain of B. burgdorferi s.l. (W97F51) was discovered, showing 33 nucleotide substitutions and one codon insertion in a 567-bp fragment of the OspB gene, compared with Borrelia bissettii (strain Ca389). The sequences of ospA, ospB, ospC,fla, and rrs genes and the rrf-rrl intergenic spacer region were compared between W97F51 and other B. burgdorferi s.l. species. Although W97F51 was most genetically related to B. bissettii, the genetic identity of W97F51 was less than that of B. bissettii conspecifics. This study documents the existence of an established population of I. scapularis and the presence of B. burgdorferi with a novel strain in southeastern Wisconsin.

Phylogenetic relationships of aquatic birnaviruses based on deduced amino acid sequences of genome segment A cDNA.

Aquatic birnaviruses, such as infectious pancreatic necrosis virus (IPNV), cause serious diseases in a variety of fish species used worldwide in aquaculture and have also been isolated from a variety of healthy fish and shellfish species. These viruses exhibit a high degree of antigenic heterogeneity and variation in biological properties such as pathogenicity, host range, and temperature of replication. To better understand genetic and biological diversity among these viruses, the nucleotide and deduced amino acid sequences were determined from cDNA of the large open reading frame (ORF) of genome segment A of the 9 type strains of Serogroup A and 4 other representative strains of Serotype A1, the predominant serotype in the United States. In addition, nucleotide and deduced amino acid sequences were determined for the VP2 coding region of a variety of isolates representing 5 of the 9 serotypes. VP2 is the major outer capsid protein of aquatic birnaviruses. RT-PCR was used to amplify a 2904 bp cDNA fragment including all but a few bp of the large ORF of genome segment A or a 1611 bp fragment representing the entire VP2 coding region. Nucleotide and deduced amino acid sequences were determined from the PCR products. Pairwise comparisons were made among our data and 2 other aquatic birnavirus sequences previously published. Several hypervariable regions were identified within the large ORF. The most divergent pair of viruses exhibited a similarity of 80.1% in the deduced amino acid sequence encoded by the large ORF. Genomic relationships revealed in a phylogenetic tree constructed from comparison of the deduced amino acid sequences of the large ORF demonstrated that these viruses were clustered into several genogroups. Phylogenetic comparison of the deduced amino acid sequences of the VP2 coding region of 28 aquatic birnavirus isolates, including the type strains of all 9 serotypes, demonstrated 6 genogroups, some of which were comprised of several genotypes. The most divergent pair of viruses exhibited a similarity of 81.2% in the deduced amino acid sequence from the VP2 coding region. In contrast to previous studies of much shorter genomic sequences within the C-terminus-pVP2/NS junction coding region, these genogroups based on the entire large ORF or the VP2 coding region generally correlated with geographical origin and serological classification. Isolates from the major Canadian serotypes were more closely related to the European isolates than to isolates from the United States.

Diversity of Babesia infecting deer ticks (Ixodes dammini).

To determine whether the presence of nonpathogenic piroplasms may confound field estimates of risk of Babesia microti infection, we identified sporozoites infecting the salivary glands of deer ticks (Ixodes dammini) by parallel microscopy and polymerase chain reaction assays. Piroplasms were evident in 14.4% of adult ticks from sites in the northcentral and northeastern United States. Of these, 83.3% contained DNA characteristic of Ba. odocoilei. This cervid piroplasm was detected in all of the sites examined and generally was more prevalent than was Ba. microti. Because deer ticks transmit both Ba. odocoilei and Ba. microti, estimates of pathogen prevalence based solely on microscopy may overestimate the risk of human babesiosis.

Population structure of Mya arenaria along the New England coastline.

Sequences of the internal transcribed spacer (ITS-1) ribosomal DNA region were compared among 88 soft-shell clams (Mya arenaria) from 12 sites (within three general areas) along the New England coast to determine whether populations were genetically heterogeneous. Two sequence variants were observed, with type 1 having a 3-nucleotide insertion and one point mutation relative to type 2. Allele-specific polymerase chain reaction (PCR); using primers specific to each sequence type, was performed to determine the distribution of individuals who had both allelic forms. DNA from soft-shell clams collected from three areas (Cobscook Bay, Maine; Gulf of Maine; and southern New England) were compared chi 2 analyses of allele-specific PCR results revealed no significant heterogeneity among the three population distributions.

Role of bird migration in the long-distance dispersal of Ixodes dammini, the vector of Lyme disease.

To evaluate the role of migratory birds in the long-distance dispersal of Ixodes dammini ticks and in the spread of Lyme disease, a 6-year study of migrating birds to an offshore New England island was conducted during 1989-1994. I. dammini are not endemic on this island, therefore allowing assessment of long-distance tick dispersal rather than local infestation. Of 11,324 spring migrants examined, 1.2% were infested with I. dammini. Of 8607 fall migrants examined, 0.2% were infested. Of nymphal ticks examined, 20% were infected with Borrelia burgdorferi. OspB DNA sequencing of 6 B. burgdorferi isolates was identical to sequences of 2 strains common in coastal Maine. It is evident that bird migration allows for long-distance dispersal of I. dammini from areas where they are endemic to areas where they are not and that a few bird species account for the majority of tick dispersal. The likelihood of establishment of enzootic Lyme disease by this mechanism is discussed.

Discriminating between Ixodes ticks by means of mitochondrial DNA sequences.

Ticks of the genus Ixodes have recently assumed prominence because they frequently serve as vectors of important zoonoses, including Lyme disease and babesiosis. The morphological characteristics that have been used in their identification often are ambiguous and are useful solely at a particular stage of development. Here we report the DNA sequence of the mitochondrially encoded 16S rRNA gene of nine different Ixodes ticks and an outgroup from another genus, Dermacentor. The sequences readily discriminate between these ticks. Samples of I. dammini from the northeastern and upper midwestern United States differ from southeastern I. scapularis at about 2% of the nucleotides. This difference is about half that separating other members of the I. ricinus group of species, but exceeds typical levels of intraspecific variation. Two major clades exist within the I. ricinus complex. One includes I. cookei, I. hexagonus, and I. angustus. The other includes I. persulcatus, I. pacificus, I. muris, I. ricinus, I. scapularis, and I. dammini. We conclude that mtDNA sequences are useful for unravelling the systematics of these important vectors of human disease.

Distribution of the Ixodes ricinus-like ticks of eastern North America.

We analyzed the geographic distribution of the Ixodes ricinus-like ticks in eastern North America by comparing the mitochondrial 16S rDNA sequences of specimens sampled directly from the field during the 1990s. Two distinct lineages are evident. The southern clade includes ticks from the southeastern and middle-eastern regions of the United States. The range of the northern clade, which appears to have been restricted to the northeastern region until the mid-1900s, now extends throughout the northeastern and middle-eastern regions. These phyletic units correspond to northern and southern taxa that have previously been assigned specific status as Ixodes dammini and Ixodes scapularis, respectively. The expanding range of I. dammini appears to drive the present outbreaks of zoonotic disease in eastern North America that include Lyme disease and human babesiosis.

Sequence variation in the outer-surface-protein genes of Borrelia burgdorferi.

Borrelia burgdorferi is a spirochete pathogen transmitted among warm-blooded hosts by ixodid ticks. Frequency-dependent selection for variant outer-surface proteins might be expected to arise in this species, since rare variants are more likely to avoid immune surveillance in previously infected hosts. We sequenced the OspA and OspB genes of nine North American strains and compared them with nine strains previously described. For each gene, the mean number of synonymous substitutions per synonymous site and the mean number of nonsynonymous substitutions per nonsynonymous site show only a twofold excess of silent mutations. Synonymous rates vary widely along the OspB protein. Some regions show a significant excess of silent substitutions, while divergence in other regions is constrained by biased base composition or selection. The presence, in antigenically important regions of the protein, of significant variation among strains, as well as evidence for recombination among strains, should be considered in attempts to develop vaccines against this disease.

Competence of Peromyscus maniculatus (Rodentia: Cricetidae) as a reservoir host for Borrelia burgdorferi (Spirochaetares: Spirochaetaceae) in the wild.

Although capable of maintaining and transmitting Borrelia burgdorferi Johnson, Schmidt, Hyde, Steigerwalt & Brenner, the causative spirochete of Lyme disease, in the laboratory, the specific ability of deer mice, Peromyscus maniculatus Le Conte, to support this zoonosis has not been established. Demonstration that P. maniculatus is a competent reservoir host in the wild would indicate that the spread of Lyme disease is not limited to the range of the primary reservoir host, P. leucopus Rafinesque. Isle au Haut, an offshore Maine island upon which the vector tick Ixodes dammini Spielman, Clifford, Piesman & Corwin has become established, supports an isolated population of mice that are exclusively P. maniculatus. We examined the reservoir competence of this species by comparing infection rates of B. burgdorferi among juvenile ticks removed from livetrapped mice on this island with those removed from P. leucopus obtained at a mainland site endemic for Lyme disease. Equivalent rates of infection among engorged larval ticks, survival of infection through the larval-nymphal molt, and the isolation of B. burgdorferi from mice at both sites attest to the reservoir competence of P. maniculatus.