Characteristics of Hard Tick Relapsing Fever Caused by Borrelia miyamotoi, United States, 2013-2019.

Borrelia miyamotoi, transmitted by Ixodes spp. ticks, was recognized as an agent of hard tick relapsing fever in the United States in 2013. Nine state health departments in the Northeast and Midwest have conducted public health surveillance for this emerging condition by using a shared, working surveillance case definition. During 2013-2019, a total of 300 cases were identified through surveillance; 166 (55%) were classified as confirmed and 134 (45%) as possible. Median age of case-patients was 52 years (range 1-86 years); 52% were male. Most cases (70%) occurred during June-September, with a peak in August. Fever and headache were common symptoms; 28% of case-patients reported recurring fevers, 55% had arthralgia, and 16% had a rash. Thirteen percent of patients were hospitalized, and no deaths were reported. Ongoing surveillance will improve understanding of the incidence and clinical severity of this emerging disease.

Jamestown Canyon virus (Bunyavirales: Peribunyaviridae) vector ecology in a focus of human transmission in New Hampshire, USA.

Jamestown Canyon virus disease (JCVD) is a potentially neuroinvasive condition caused by the arbovirus Jamestown Canyon virus (JCV). Human cases of JCVD have increased in New Hampshire (NH) over the past decade, but vector surveillance is limited by funding and person power. We conducted mosquito surveillance with a focus on human JCVD cases south central NH during 2021. Routine surveillance with CDC miniature traps baited with CO2 (lights removed) was supplemented by a paired trapping design to test the collection efficiency of octenol, and New Jersey light traps. We performed virus testing, blood meal analysis, and compared morphological identification with DNA barcoding. Over 50,000 mosquitoes were collected representing 28 species. Twelve JCV-positive pools were derived from 6 species of more than 1,600 pools tested. Of those, Aedes excrucians/stimulans (MLE 4.95, Diptera: Culicidae, Walker, 1856, 1848), and Aedes sticticus (MLE 2.02, Meigen, 1838) had the highest JCV infection rates, and Aedes canadensis (MLE 0.13, Theobold, 1901) and Coquillettidia perturbans (0.10, Diptera: Culicidae, Walker, 1856) had the lowest infection rates. One hundred and fifty-one blood meals were matched to a vertebrate host. All putative vectors fed on the amplifying host of JCV, white-tailed deer (36-100% of bloodmeals). Putative vectors that fed on human hosts included Aedes excrucians (8%), Anopheles punctipennis (25%, Diptera: Culicidae, Say, 1823), and Coquillettidia perturbans (51%). CDC traps baited with CO2 were effective for collecting putative vectors. DNA barcoding enhanced morphological identifications of damaged specimens. We present the first ecological overview of JCV vectors in NH.

Biological control of Aedes mosquito larvae with carnivorous aquatic plant, Utricularia macrorhiza.

BACKGROUND: Biological controls with predators of larval mosquito vectors have historically focused almost exclusively on insectivorous animals, with few studies examining predatory plants as potential larvacidal agents. In this study, we experimentally evaluate a generalist plant predator of North America, Utricularia macrorhiza, the common bladderwort, and evaluate its larvacidal efficiency for the mosquito vectors Aedes aegypti and Aedes albopictus in no-choice, laboratory experiments. We sought to determine first, whether U. macrorhiza is a competent predator of container-breeding mosquitoes, and secondly, its predation efficiency for early and late instar larvae of each mosquito species. METHODS: Newly hatched, first-instar Ae. albopictus and Ae. aegypti larvae were separately exposed in cohorts of 10 to field-collected U. macrorhiza cuttings. Data on development time and larval survival were collected on a daily basis to ascertain the effectiveness of U. macrorhiza as a larval predator. Survival models were used to assess differences in larval survival between cohorts that were exposed to U. macrorhiza and those that were not. A permutation analysis was used to investigate whether storing U. macrorhiza in laboratory conditions for extended periods of time (1 month vs 6 months) affected its predation efficiency. RESULTS: Our results indicated a 100% and 95% reduction of survival of Ae. aegypti and Ae. albopictus larvae, respectively, in the presence of U. macrorhiza relative to controls within five days, with peak larvacidal efficiency in plant cuttings from ponds collected in August. Utricularia macrorhiza cuttings, which were prey-deprived, and maintained in laboratory conditions for 6 months were more effective larval predators than cuttings, which were maintained prey-free for 1 month. CONCLUSIONS: Due to the combination of high predation efficiency and the unique biological feature of facultative predation, we suggest that U. macrorhiza warrants further development as a method for larval mosquito control.