Transmission of Hepatitis A Virus through Combined Liver-Small Intestine-Pancreas Transplantation.

Although transmission of hepatitis A virus (HAV) through blood transfusion has been documented, transmission through organ transplantation has not been reported. In August 2015, state health officials in Texas, USA, were notified of 2 home health nurses with HAV infection whose only common exposure was a child who had undergone multi-visceral organ transplantation 9 months earlier. Specimens from the nurses, organ donor, and all organ recipients were tested and medical records reviewed to determine a possible infection source. Identical HAV RNA sequences were detected from the serum of both nurses and the organ donor, as well as from the multi-visceral organ recipient's serum and feces; this recipient's posttransplant liver and intestine biopsy specimens also had detectable virus. The other organ recipients tested negative for HAV RNA. Vaccination of the donor might have prevented infection in the recipient and subsequent transmission to the healthcare workers.

Geographic distribution and genetic diversity of the Ehrlichia sp. from Panola Mountain in Amblyomma americanum.

BACKGROUND: A novel Ehrlichia, closely related to Ehrlichia ruminantium, was recently discovered from Panola Mountain State Park, GA, USA. We conducted a study to determine if this agent was recently introduced into the United States. METHODS: We developed a sensitive PCR assay based on the conserved gltA (citrate synthase) gene and tested DNA samples extracted from 1964 field-collected and 1835 human-biting Amblyomma americanum from 23 eastern states of the USA. RESULTS: The novel agent was detected in 36 ticks collected from 10 states between 1998 and 2006. Infected ticks were collected both from vegetation (n = 14, 0.7%) and from humans (n = 22, 1.2%). Fragments of the conserved gltA gene and the variable map1 gene were sequenced from positive samples. Two distinct clades, with 10.5% nucleic acid divergence over the 730 bp map1 sequence, were identified. CONCLUSION: These data suggest that the Panola Mountain Ehrlichia was not recently introduced to the United States; this agent has an extensive distribution throughout the range of its tick vector, has been present in some locations for several years, and displays genetic variability. Furthermore, people in several states were exposed to this agent through the bite of infected ticks, underscoring the potential public health risk of this emerging ehrlichiosis.

Prevalence of Ehrlichia, Borrelia, and Rickettsial agents in Amblyomma americanum (Acari: Ixodidae) collected from nine states.

Ambyomma americanum (L.) (Acari: Ixodidae) is an aggressive tick that feeds on humans during all postembryonic life stages. In many regions of the United States, it is the tick most commonly found attached to humans. Public health interest has grown recently, due to the recognition of new human pathogens transmitted by A. americanum and the expanding distribution of the tick. A. americanum is a vector of several bacteria pathogenic to humans. Ehrlichia chaffeensis and Ehrlichia ewingii cause moderate-to-severe febrile illness. "Rickettsia amblyommii," a member of the spotted fever group Rickettsia, also has recently been implicated as a possible human pathogen based on serologic evidence from persons recovering from illness after a tick bite. We have determined the prevalence of infection of Ehrlichia chaffeensis, E. ewingii, "Borrelia lonestari", and R. amblyommii within A. americanum ticks from 29 sites in nine states. Overall infection prevalences were 4.7% for E. chaffeensis (range, 0-27%), 3.5% for E. ewingii (range, 0-18.6%), 2.5% for B. lonestari (range, 0-12.2%), and 41.2% for R. amblyommii (range, 0-84.0%). In addition, 87 ticks (4.3%) were infected with two or more bacteria. This report documents new distribution records for E. ewingii, B. lonestari, and R. amblyommii and underscores the nonhomogeneous distribution of pathogen foci of infection. Additional surveillance throughout the range ofA. americanum is warranted to increase physician and public awareness of the risk of disease to humans from exposure to the agents transmitted by this tick.

Inferring the population structure and demographic history of the tick, Amblyomma americanum Linnaeus.

A hierarchial population genetic study was conducted on 703 individual Amblyomma americanum from nine populations in Georgia, U.S.A. Populations were sampled from the Coastal Plain, midland Piedmont region, and the upper Piedmont region. Twenty-nine distinct haplotypes were found. A minimum spanning tree was constructed that indicated these haplotypes comprised two lineages, the root of which was distinctly star-like. The majority of the variation found was among ticks within each population, indicating high amounts of gene flow and little genetic differentiation between the three regions. An overall F(ST) value of 0.006 supported the lack of genetic structuring between collection sites in Georgia. Mantel regression analysis revealed no isolation by distance. Signatures of population expansion were detected in the shapes of the mismatch distribution and tests of neutrality. The absence of genetic differentiation combined with the rejection of the null model of isolation by distance may indicate recent range expansion in Georgia or insufficient time to reach an equilibrium where genetic drift may have affected allele frequencies. Alternatively, the high degree of panmixia found within A. americanum in Georgia may be due to bird-mediated dispersal of ticks increasing the genetic similarity between geographically separated populations.

Relative encounter frequencies and prevalence of selected Borrelia, Ehrlichia, and Anaplasma infections in Amblyomma americanum and Ixodes scapularis (Acari: Ixodidae) ticks from central New Jersey.

To evaluate their relative importance in tick-borne disease transmission in New Jersey, host-seeking Amblyomma americanum (L.) and Ixodes scapularis Say adults and nymphs were collected during spring activity periods in 2003 and 2004 to determine relative frequencies at which these ticks were encountered from an area known to be hyperendemic for Lyme disease. Although similar numbers of the two species were encountered during early spring of both years, A. americanum were encountered more often later in the season and exhibited a longer activity period than I. scapularis. A. americanum nymphs were collected at frequencies between 2.6 and 7.3 times higher than I. scapularis nymphs. Polymerase chain reaction (PCR) analysis of 121 A. americanum adults yielded infection prevalences of 9.1% for Borrelia lonestari, 12.3% for Ehrlichia chaffeenensis, and 8.2% for E. ewingii, and coinfection prevalences of 4.1% for E. chaffeensis/E. ewingii and 0.8% for E. chaffeensis/B. lonestari. Infection prevalences in 147 I. scapularis adults were 50.3% for B. burgdorferi, 6.1% for Anaplasma (Ehrlichia) phagocytophilum, and 1.4% for a recently described novel Borrelia species, whereas the coinfection prevalences were 2.7% for B. burgdorferi/A. phagocytophilum, 0.7% for B. burgdorferi/novel Borrelia, and 0.7% for A. phagocytophilum/novel Borrelia. The B. burgdorferi infection prevalence in I. scapularis was considerably higher than that in A. americanum. However, the higher A. americanum encounter frequencies compared with I. scapularis may result in increased risk of acquiring exposure to A. americanum-transmitted pathogens. The potential public health implications of these results are discussed.

Prevalence of the agent of human granulocytic ehrlichiosis in Ixodes scapularis (Acari: Ixodidae) in the coastal southeastern United States.

Human granulocytic ehrlichiosis (HGE) is an emerging tick-borne disease recently recognized in the United States. The blacklegged tick, Ixodes scapularis Say, is the principle vector in the eastern United States. The disease has been commonly reported in the northeastern and upper midwestern states; however, suitable vectors and reservoir hosts exist in the southeast. To assay the prevalence of the HGE agent in vector ticks, we screened 818 individual I. scapularis from 15 locations in South Carolina, Georgia, and Florida using nested polymerase chain reaction, which targets the HGE agent 16S rRNA gene. Prevalence among locations ranged from 0 to 20%. The overall average prevalence of 15 sites was 1.6% (n = 818). Verification by sequencing the 16S rDNA from the positive samples showed 99.8-100% nucleotide identities with the sequences of the HGE agent in GenBank. These results were supported by the phylogenetic analysis using 16S rDNA sequences.

Detection of Ehrlichia chaffeensis in adult and nymphal Amblyomma americanum (Acari: Ixodidae) ticks from Long Island, New York.

The lone star tick, Amblyomma americanum (L.), has increased in abundance in several regions of the northeastern United States, including areas of Long Island, NY. Adult and nymphal stage A. americanum collected from several sites on Long Island were evaluated for infection with Ehrlichia chaffeensis, the causative agent of human monocytic ehrlichiosis (HME), by using a nested polymerase chain reaction assay. Fifty-nine (12.5%) of 473 adults and eight of 113 pools of five nymphs each (estimated minimum prevalence of infection 1.4%) contained DNA of E. chaffeensis. These data, coupled with the documented expansion of lone star tick populations in the northeastern United States, confirm that E. chaffeensis is endemic to many areas of Long Island and that HME should be considered among the differential diagnoses of the many distinct tick-borne diseases that occur in this region.

The use of the nuclear protein-encoding gene, RNA polymerase II, for tick molecular systematics.

Phylogenetic studies of ticks have been increasing in recent years, particularly in the use of molecular data. However, all of the studies to date are either limited to the mitochondrial genome or to a few nuclear ribosomal genes. There is a need to explore the use of nuclear protein-encoding genes because these genes direct most aspects of the phenotypic traits in the development of an organism. We report here the test of a nuclear protein-encoding gene, RNA polymerase II, for the phylogenetic study of ticks. Thirty-eight ticks representing 26 species of hard and soft ticks were chosen for the study. The pairwise divergences among sampled species are ranged from 0.3 to 15.2% and most of the substitutions are transitions. In addition, the nucleotide composition is not obviously biased in POL II gene. The trees inferred from the POL II sequences using maximum parsimony (MP), neighbor joining (NJ), and maximum likelihood (ML) by PAUP* and MrBayes are largely concordant with the existing phylogenies. Our study demonstrated that POL II gene sequences contain strong phylogenetic signals in ticks at the generic and higher levels. POL II has proven to be a useful gene for resolving tick phylogeny.