Post-Hurricane Rita mosquito surveillance was carried out in 4 east Texas counties to determine mosquito abundance, species composition, and need for mosquito control. Subsequently, aerial applications of naled (Dibrom) for mosquito control were made by the Air Force Aerial Spray Flight, while continued surveillance documented the efficacy of the applications. Psorophora columbiae was the predominant species in landing counts. Twenty-two mosquito species were represented in light trap collections with Aedes atlanitcus/tormentor, Culex nigripalpus, Ae. vexans, and Ps. columbiae making up 91% of the total. A total of 102,001 ha (252,052 acres) were aerially treated based on high mosquito abundance, exposure of first responders and residents to nuisance biting, and local interruption of electric utilities. A significant 90% decline in mosquito abundance was observed posttreatment.
ABSTRACT. The geographical distribution of Bacillus anthracis strains and isolates bearing some of the same genetic markers as the Amerithrax Ames isolate was examined and evaluated. At least one mechanism for the horizontal movement of genetic markers was shown amongst isolates and closely related species and the effect of such mixing was demonstrated on phenotype. The results provided potential mechanisms by which attempts to attribute isolates of Bacillus anthracis to certain geographical and isolate sources may be disrupted.Bacillus anthracis appears to be a bacterium that has unique qualities that might allow using the genotype alone to determine the geographical distribution of genetic markers. It is extremely genetically homogeneous across its worldwide distributed strains (Keim et al. 1997(Keim et al. , 2000(Keim et al. , 2002. However, there are enough single-nucleotide polymorphisms (SNPs) and variable tandem repeat sequence number differences among various isolates to appear to distinguish B. anthracis from various locales. This lack of substantial variability may be attributed to the low-passage number of natural anthrax bacteria and their relative isolation to very limited areas because they are purported to reside in soil as spores for decades before infecting a host and completing another cycle of replication (Keim et al. 1997). The laboratory mutation rate of B. anthracis is ≈2 × 10 -5 (Keim et al. 2001) and the natural mutation rate is ≈2 × 10 -10 (Van Ert et al. 2007), assuming little or no recombination, which may not be the case (Ko et al. 2004); however, we have previously shown that nitration conditions in vitro easily generate profound mutations . Such conditions mimic the inflammatory activity of nitric-oxide synthase, NADPH oxidase and peroxidase in leukocytes against microbes in vivo. The sheer number of organisms produced in the terminal infection of a large animal host, such as a cow, should easily produce mutations well represented in the final spore yield based on the number of spores produced alone. A 550-kg cow could yield 60 mL/kg blood containing ≈10 8 spores per mL (Swartz 2001), totaling 3.3 × 10 12 spores per carcass. This yield could contain from 3.3 × 10 2 to 3.3 × 10 7 mutants. MATERIALS AND METHODSMicrobiological methods. β-Hemolysis was observed on tryptic soy agar plates with 5 % sheep blood (BAP; Remel) after 18 h of growth at 37 °C. Cherry γ phage spot tests were performed on host lawns derived from tryptic soy broth (TSB) cultures, incubated for 18 h at 37 °C with shaking (150 rpm). Plates were swabbed bidirectionally with host lawn, incubated for 2 h at 37 °C, spot-inoculated with 20 μL of undiluted Cherry γ phage, and incubated for 18 h at 37 °C. Antibiotic disk sensitivities were performed with disks placed directly on lawns omitting the 2-h incubation step used for the phage tests. Cherry γ phage rescue used 500-μL aliquots of host culture (host-inoculated TSB incubated for 18 h at 37 °C with shaking) seeded with 20 μL of serially diluted Cherry γ phage (10 0 , 1...
We are reporting the first known isolation of the Q-fever agent Coxiella burnetii from field-collected cayenne ticks Amblyomma cajennense in North America. Q-fever affects a number of domestic ungulates where it can lead to abortion in sheep and goats. There is far less known about the disease's effects on wild species, primarily because of the tendency of the disease to self resolve and to provide long-term immunity to subsequent infections. The first recovery of C. burnetii in North America was from the tick species Dermacentor andersoni. Since the original isolation C. burnetii has been recovered from five other North American tick species. The currently accepted mode for the majority of human infections is inhalation. The Centers for Disease Control and Prevention, Division of Viral and Rickettsial Diseases, Rickettsial Zoonoses Branch asserts the Q-fever agent as requiring as few as one organism to cause disease via inhalation in susceptible humans. However, with more and more isolations from ticks, evidence linking C. burnetii and ticks is mounting. The true role of tick species as competent vectors is still unconfirmed. Preemptive field collections of possible vector arthropods, hosts, and reservoirs can provide invaluable baseline environmental data that will prove supportive in follow-up studies and abatement efforts.
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