By Linda on Jun 27, 2010 in Infections | comments(0)
Excerpt:
In this study, we evaluated Amblyomma americanum (lone star tick)
in Mississippi for the presence of Ehrlichia chaffeensis,
causative agent of human monocytic ehrlichiosis; Ehrlichia
ewingii, causative agent of human and canine granulocytic
ehrlichiosis; Borrelia lonestari, putative agent of southern
tick-associated rash illness; Francisella tularensis, the agent
of tularemia; and Rickettsia spp., particularly R. amblyommii, a
suspected pathogen. We collected adult A. americanum from four
regions of Mississippi: Northeast, Northwest, Southeast, and
East. Of the ticks collected, 192 were dissected and DNA was
extracted for nested polymerase chain reaction (PCR) assays to
detect the above bacteria. In all, 3% of tick extracts had
evidence of Borrelia sp., 4% for E. chaffeensis, 6% for E.
ewingii, and 44% for a Rickettsia species. As determined by
sequencing, most Rickettsia spp. were R. amblyommii. In addition,
extracts from 42 pools (total of 950) of larval A. americanum
collected in Southwest Mississippi were tested for the presence
of E. chaffeensis and Rickettsia species. Of these extracts from
pools, nine of 37 (24%) were PCR positive for a Rickettsia sp.,
most often, R. amblyommii; none had evidence of E. chaffeensis,
supporting the ability of lone star ticks to transovarially
transmit R. amblyommii, but not E. chaffeensis. This study
demonstrates E.
By Linda on Feb 24, 2010 in Infections | comments(0)
Full article: http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=20052776&retmode=ref&cmd=prlinks
PMID: 20052776
Excerpt:
Ehrlichiosis, a tickborne illness transmitted by tick vectors Amblyomma
americanum and Ixodes scapularis, can be acquired in endemic areas. Clinical
manifestations range from asymptomatic to fulminant in nature. We report three
cases of ehrlichiosis in pediatric oncology patients, one of whom was a stem
cell transplant recipient. Early symptoms included fever, malaise, and vague
gastrointestinal symptoms. Laboratory abnormalities were initially attributed to
chemotherapy toxicity. Illness was severe in all three patients and one patient
died even after initiation of doxycycline.
By Linda on Dec 19, 2009 in Infections | comments(0)
Rates of infection of Amblyomma americanum (L.) by Ehrlichia chaffeensis were
compared in 100 ticks collected from sites in each of four states: Indiana,
North Carolina, Kentucky, and Mississippi. The overall infection rates were
similar among sites, ranging from 1 to 4%. Because pathogenic differences may
exist between E. chaffeensis strains, nested polymerase chain reaction (PCR)
amplification of the variable-length PCR target (VLPT), and sequencing of the
amplicons were performed to differentiate between strains. The most common
infecting strains at all sites exhibited a repeat profile of 1,2,3,4
(corresponding to the Arkansas/Jax/Osceola and Liberty strains). To determine
whether the minimum infection rates (MIRs) or the most common infecting strain
were changing over time in southern Indiana sites, 2765 ticks from six counties
in 2000 and 837 ticks from seven counties in 2004 also were examined in pools of
five ticks per pool. The MIRs for 2000 and 2004 were 3.5 and 4.2% respectively,
suggesting that the overall MIRs remained low. At two sites, in Pike and
Harrison counties, however, infection rates more than doubled from 2000 to 2004
(7 to 16% and 0.3 to 2.7% respectively). Across all sites, the most common
infecting strains (Arkansas/Jax/Osceola and Liberty) did not significantly
change (68% in 2000; 79% in 2004). Continued
