Increasing Babesiosis in Southeastern Pennsylvania, 2008-2017

EVIDENCE OF PROTOZOAN AND BACTERIAL INFECTION AND CO-INFECTION AND PARTIAL BLOOD FEEDING IN THE INVASIVE TICK HAEMAPHYSALIS LONGICORNIS IN PENNSYLVANIA

The Asian longhorned tick, Haemaphysalis longicornis, an invasive tick species in the United States, has been found actively host-seeking while infected with several human pathogens. Recent work has recovered large numbers of partially engorged, host-seeking H. longicornis, which together with infection findings raises the question of whether such ticks can reattach to a host and transmit pathogens while taking additional bloodmeals. Here we conducted molecular blood meal analysis in tandem with pathogen screening of partially engorged, host-seeking H. longicornis to identify feeding sources and more inclusively characterize acarological risk. Active, statewide surveillance in Pennsylvania from 2020 to 2021 resulted in the recovery of 22/1,425 (1.5%) partially engorged, host-seeking nymphal and 5/163 (3.1%) female H. longicornis. Pathogen testing of engorged nymphs detected 2 specimens positive for Borrelia burgdorferi sensu lato, 2 for Babesia microti, and 1 co-infected with Bo. burgdorferi s.l. and Ba. microti. No female specimens tested positive for pathogens. Conventional PCR blood meal analysis of H. longicornis nymphs detected avian and mammalian hosts in 3 and 18 specimens, respectively. Mammalian blood was detected in all H. longicornis female specimens. Only 2 H. longicornis nymphs produced viable sequencing results and were determined to have fed on black-crowned night heron, Nycticorax nycticorax. These data are the first to molecularly confirm H. longicornis partial blood meals from vertebrate hosts and Ba. microti infection and co-infection with Bo. burgdorferi s.l. in host-seeking specimens in the United States, and the data help characterize important determinants indirectly affecting vectorial capacity. Repeated blood meals within a life stage by pathogen-infected ticks suggest that an understanding of the vector potential of invasive H. longicornis populations may be incomplete without data on their natural host-seeking behaviors and blood-feeding patterns in nature.

Prevalence and phylogenetic analysis of Babesia parasites in reservoir host species in Fujian province, Southeast China

Babesiosis is a tick-borne disease that mainly affects small mammals and has been reported in at least five provinces in China. However, the host range and geographical distribution of the parasite in Fujian province are unclear. Therefore, we investigated the prevalence and genetic characteristics of Babesia in Fujian province, Southeast China, between 2015 and 2020. Rodent blood samples were collected from 26 different surveillance sites across Fujian province. Genomic DNA was extracted to screen for Babesia infection using polymerase chain reaction based on 18S rRNA. DNA samples from 316 domestic goats, 85 water buffalo, 56 domestic dogs and 18 domestic pigs were examined. The prevalence of Babesia was statistically analysed using the Chi-square test or Fisher's exact test. Babesia infections were detected in 3.96% (43/1,087; 95%CI: 2.80%, 5.12%) of rodents and 1.26% (6/475; 95%CI: 0.26%, 2.26%) of other mammals. Multivariate logistic regression analysis revealed that irrigated cropland, shrubs and forests were risk factors for Babesia microti infections. The infection rates among domestic pigs, dogs and goats were 5.56%, 1.79% and 1.27%, respectively, with no infection found in water buffalo. The 18S rRNA gene sequencing revealed that rodents were infected with Babesia (sensu lato), whereas other mammals were infected with Babesia (sensu stricto). The geographical distribution and phylogenetic relationship of Babesia was determined in Southeast China. Mammals, particularly wild rodents, maybe the main natural hosts of Babesia in Fujian. Our findings provide a foundation for public health officials to develop prevention and control measures for Babesia.

High Asymptomatic Cases of Babesiosis in Dogs and Comparison of Diagnostic Performance of Conventional PCR vs Blood Smears

PURPOSE

Babesiosis is one of the most important globally extended and quickly spreading tick-borne infections of dogs. Diagnosis of babesiosis in Sri Lanka is based on clinical signs followed by thin blood smears which could be error-prone due to undetected early infections, absence of clinical signs or low parasitemia. The present study investigated the prevalence of babesiosis in dogs presented to the Veterinary Teaching Hospital (VTH) at the Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, for treatments, vaccinations, and regular check-ups, and compared the diagnosis methods of microscopy and molecular analysis.

METHODS

Blood samples from dogs were collected from January to June 2019. First, Giemsa stained blood smears were prepared, and then the blood samples were subjected to PCR using genus-specific primers to amplify a 411-450 bp region in the 18S rRNA gene. Twenty samples from PCR amplified products were sequenced for species identification and phylogenetic analysis. Clinical signs of the dogs were noted down, and ticks were also collected from dogs if any.

RESULTS

Results show a very high prevalence of canine babesiosis (78.6%) among the dogs brought to the VTH. The parasite was identified microscopically and genetically as Babesia gibsoni. A large percentage (66.7%) of infections was asymptomatic. Out of 42 blood samples, 19 (45.2%) were microscopically positive for babesiosis while 33 (78.6%) were PCR positive, showing a significant difference in the two methods of diagnosis (chi-square test, χ² = 9.462, p = 0.002). Three tick species: Rhipicephalus haemaphysaloides, Haemaphysalis bispinosa, and Rhipicephalus sanguineus were found attached to the dogs.

CONCLUSION

This study shows a very high prevalence of canine babesiosis among dogs in the Kandy area. Most of these infections might go undetected if only microscopy was used to diagnose. An improved, rapid diagnostic method such as the novel, PCR-based point-of-care diagnostic method that detects very low parasitemia within 30 min is needed. Moreover, as most infected dogs did not show clinical signs, they may act as reservoirs of infection. The ability of asymptomatic dogs to spread babesiosis should be investigated.

Impact of a Severe Rocky Mountain Spotted Fever Case on Treatment Practices at an Academic Institution Within a Nonendemic Area

INTRODUCTION

Rocky Mountain spotted fever (RMSF) is a bacterial disease associated with morbidity and mortality when untreated. The primary study objectives are to describe clinician diagnostic and treatment practices in a nonendemic area after the occurrence of an unrecognized severe pediatric presumed RMSF case (index case). We hypothesized that inpatient diagnostic testing frequency and initiation of empiric treatment will increase after the index case.

METHODS

We performed a retrospective chart review of patients aged less than 18 y evaluated for RMSF at Penn State Hershey Children's Hospital between 2010 and 2019. We divided the study population into 2 groups (preindex and postindex) and evaluated patient characteristics, RMSF testing completion, and timing of doxycycline administration.

RESULTS

Fifty-four patients (14 [26%] preindex and 40 [74%] postindex) were included. Age (median [25^th percentile, 75^th percentile]) decreased from 14.5 y (8.6, 16) preindex to 8.3 y (3.6, 14) postindex. Twelve (86%) preindex and 31 (78%) postindex patients received empiric doxycycline (P=0.70). Four years after the index case, a decrease in empiric and urgent initiation of doxycycline administration was noted. One case of severe RMSF was diagnosed 4 y after the index case.

CONCLUSIONS

Our study found that inpatient RMSF testing increased after the index case, but not all patients received empiric treatment. This may represent an underappreciation of RMSF severity even after a recent devastating case. We suggest that when severe rare but possibly reversible diseases, such as RMSF occur, all clinicians are educated on the diagnostic and treatment approach to reduce the morbidity and mortality risk.

Rise in Babesiosis Cases, Pennsylvania, USA, 2005-2018

Babesiosis is an emerging infection in the state of Pennsylvania, and clinicians need to be made aware of its clinical manifestations as well as the risk factors associated with severe disease. Before 2010, our tertiary academic center in central Pennsylvania previously saw zero cases of babesiosis. We saw our first confirmed case of Babesia infection acquired in Pennsylvania in 2011; we recorded 2 confirmed cases in 2017 and 4 confirmed cases in 2018. All 4 cases from 2018 were thought to be acquired in southcentral Pennsylvania counties, whereas prior reports of cases were predominately in the southeast and northeast counties of the state.

Babesiosis Occurrence Among United States Medicare Beneficiaries, Ages 65 and Older, During 2006-2017: Overall and by State and County of Residence

Background

Human babesiosis is a mild-to-severe parasitic infection that poses health concerns especially in older and other at-risk populations. The study objective was to assess babesiosis occurrence among US Medicare beneficiaries, ages 65 and older, during 2006-2017.

Methods

Our retrospective claims-based study used Medicare databases. Babesiosis cases were identified using recorded diagnosis codes. The study estimated rates (per 100 000 beneficiary-years) overall, by year, diagnosis month, demographics, and state and county of residence.

Results

Nationwide, 19 469 beneficiaries had babesiosis recorded, at a rate of 6 per 100 000 person-years, ranging from 4 in 2006 to 9 in 2017 (P < .05). The highest babesiosis rates by state were in the following: Massachusetts (62), Rhode Island (61), Connecticut (51), New York (30), and New Jersey (19). The highest rates by county were in the following: Nantucket, Massachusetts (1089); Dukes, Massachusetts (236); Barnstable, Massachusetts (213); and Dutchess, New York (205). Increasing rates, from 2006 through 2017 (P < .05), were identified in multiple states, including states previously considered nonendemic. New Hampshire, Maine, Vermont, Pennsylvania, and Delaware saw rates increase by several times.

Conclusions

Our 12-year study shows substantially increasing babesiosis diagnosis trends, with highest rates in well established endemic states. It also suggests expansion of babesiosis infections in other states and highlights the utility of real-world evidence.