Pregnancy of Unknown Location: A Survey-Based Evaluation of When and Why Physicians Intervene?

INTRODUCTION: Management of pregnancies of unknown location (PUL) is a complex challenging clinical situation with possibilities for pitfalls. Obstetricians and gynaecologists of varied levels of training and experience from Canada and the Nordic countries were questioned about their approach when faced with PUL. METHOD: A 13-item web-based questionnaire was used to evaluate physicians' behaviors by surveying their management of a PUL encountered at different levels of human chorionic gonadotropin (hCG). They were queried regarding the level of hCG at which they would take management action in an asymptomatic PUL, in a given scenario. RESULTS: Three hundred fifty three questionnaires were completed resulting in a response rate, representing completeness of the survey, of 78.6%. Three distinct hCG thresholds, at which intervention to interrupt a PUL would be considered, dominated the responses. Thirty seven percent of physicians would intervene at hCG levels between 1000-3000 IU, 22% selected the 4000-6000 IU range, and 13% would only intervene if the hCG level exceeded 10 000 IU. These ranges were similar across different levels of clinical experience. In addition to hCG values, a patient's desire to keep the pregnancy, the development of new symptoms, and the expected gestational age were the other principal factors influencing the decision to intervene. CONCLUSION: There appears to be little consensus regarding the hCG threshold at which medical intervention should be initiated in an asymptomatic pregnancy of unknown location and further studies to justify earlier or later intervention are needed to determine the appropriate time for intervention.

Diabetes in Pregnancy.

OBJECTIVE: This guideline reviews the evidence relating to the diagnosis and obstetrical management of diabetes in pregnancy. OUTCOMES: The outcomes evaluated were short- and long-term maternal outcomes, including preeclampsia, Caesarean section, future diabetes, and other cardiovascular complications, and fetal outcomes, including congenital anomalies, stillbirth, macrosomia, birth trauma, hypoglycemia, and long-term effects. EVIDENCE: Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary (MeSH terms "diabetes" and "pregnancy"). Where appropriate, results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials. VALUES: The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). SUMMARY STATEMENTS: Recommendations It is recognized that the use of different diagnostic thresholds for the "preferred" and "alternative" strategies could cause confusion in certain settings. Despite this, the committee has identified the importance of remaining aligned with the current Canadian Diabetes Association 2013 guidelines as being a priority. It is thus recommended that each care centre strategically align with 1 of the 2 strategies and implement protocols to ensure consistent and uniform reporting of test results.

Le diabète pendant la grossesse.

OBJECTIF: La présente Directive passe en revue les données probantes liées au diagnostic et à la prise en charge obstétricale du diabète durant la grossesse. ISSUES: Les issues évaluées étaient les issues maternelles à court et à long terme, dont la prééclampsie, la césarienne, le diabète éventuel et d'autres complications cardiovasculaires et les issues fœtales, dont les anomalies congénitales, la mortinaissance, la macrosomie, le traumatisme de la naissance, l'hypoglycémie et les effets à long terme. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans PubMed et The Cochrane Library au moyen d'un vocabulaire contrôlé (termes MeSH « diabète ¼ et « grossesse ¼) appropriés. Le cas échéant, les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Aucune limite n'a été imposée en matière de date, mais les résultats ont été limités aux articles publiés en anglais ou en français. VALEURS: La qualité des résultats a été évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Joint SOGC-CCMG Opinion for Reproductive Genetic Carrier Screening: An Update for All Canadian Providers of Maternity and Reproductive Healthcare in the Era of Direct-to-Consumer Testing.

OBJECTIVE: This guideline was written to update Canadian maternity care and reproductive healthcare providers on pre- and postconceptional reproductive carrier screening for women or couples who may be at risk of being carriers for autosomal recessive (AR), autosomal dominant (AD), or X-linked (XL) conditions, with risk of transmission to the fetus. Four previous SOGC- Canadian College of Medical Geneticists (CCMG) guidelines are updated and merged into the current document. INTENDED USERS: All maternity care (most responsible health provider [MRHP]) and paediatric providers; maternity nursing; nurse practitioner; provincial maternity care administrator; medical student; and postgraduate resident year 1-7. TARGET POPULATION: Fertile, sexually active females and their fertile, sexually active male partners who are either planning a pregnancy or are pregnant (preferably in the first trimester of pregnancy, but any gestational age is acceptable). OPTIONS: Women and their partners will be able to obtain appropriate genetic carrier screening information and possible diagnosis of AR, AD, or XL disorders (preferably pre-conception), thereby allowing an informed choice regarding genetic carrier screening and reproductive options (e.g., prenatal diagnosis, preimplantation genetic diagnosis, egg or sperm donation, or adoption). OUTCOMES: Informed reproductive decisions related to genetic carrier screening and reproductive outcomes based on family history, ethnic background, past obstetrical history, known carrier status, or genetic diagnosis. SOGC REPRODUCTIVE CARRIER SCREENING SUMMARY STATEMENT (2016): Pre-conception or prenatal education and counselling for reproductive carrier screening requires a discussion about testing within the three perinatal genetic carrier screening/diagnosis time periods, which include pre-conception, prenatal, and neonatal for conditions currently being screened for and diagnosed. This new information should be added to the standard reproductive carrier screening protocols that are already being utilized by the most responsible maternity provider through the informed consent process with the patient. (III-A; GRADE low/moderate) SOGC OVERVIEW OF RECOMMENDATIONS QUALITY AND GRADE: There was a strong observational/expert opinion (quality and grade) for the genetic carrier literature with randomized controlled trial evidence being available only for the invasive testing. Both the Canadian Task Force on Preventive Health Care quality and classification and the GRADE evidence quality and grade are provided. EVIDENCE: MEDLINE; PubMed; government neonatal screening websites; key words/common reproductive genetic carrier screened diseases/previous SOGC Guidelines/medical academic societies (Society of Maternal-Fetal Medicine [SMFM]; American College of Medical Genetics and Genomics; American College of Obstetricians and Gynecologists [ACOG]; CCMG; Royal College Obstetrics and Gynaecology [RCOG] [UK]; American Society of Human Genetics [ASHG]; International Society of Prenatal Diagnosis [ISPD])/provincial neonatal screening policies and programs; search terms (carrier screening, prenatal screening, neonatal genetic/metabolic screening, cystic fibrosis (CF), thalassemia, hemoglobinopathy, hemophilia, Fragile X syndrome (FXS), spinal muscular atrophy, Ashkenazi Jewish carrier screening, genetic carrier screening protocols, AR, AD, XL). SEARCH PERIOD: 10 years (June 2005-September 2015); initial search dates June 30, 2015 and September 15, 2015; completed final search January 4, 2016. Validation of articles was completed by primary authors RD Wilson and I De Bie. BENEFITS, HARMS, AND COST: Benefits are to provide an evidenced based reproductive genetic carrier screening update consensus based on international opinions and publications for the use of Canadian women, who are planning a pregnancy or who are pregnant and have been identified to be at risk (personal or male partner family or reproductive history) for the transmission of a clinically significant genetic condition to their offspring with associated morbidity and/or mortality. Harm may arise from having counselling and informed testing of the carrier status of the mother, their partner, or their fetus, as well as from declining to have this counselling and informed testing or from not having the opportunity for counselling and informed testing. Costs will ensue both from the provision of opportunities for counselling and testing, as well as when no such opportunities are offered or are declined and the birth of a child with a significant inherited condition and resulting morbidity/mortality occurs; these comprise not only the health care costs to the system but also the social/financial/psychological/emotional costs to the family. These recommendations are based on expert opinion and have not been subjected to a health economics assessment and local or provincial implementation will be required. GUIDELINE UPDATE: This guideline is an update of four previous joint SOGC-CCMG Genetic Screening Guidelines dated 2002, 2006, 2008, and 2008 developed by the SOGC Genetic Committee in collaboration with the CCMG Prenatal Diagnosis Committee (now Clinical Practice Committee). 2016 CARRIER SCREENING RECOMMENDATIONS.

Prolonged second stage of labour and the risk for subsequent preterm birth.

OBJECTIVE: To assess whether prolonged second stage of labour influences the gestational age at the subsequent delivery. METHODS: We performed a retrospective cohort study. Clinical information was retrieved from the McGill Obstetrical and Neonatal Database for the period of January 2001 to February 2008. We evaluated primiparous women with term singleton pregnancies who reached the second stage of labour. Women were divided into two groups, according to the duration of the second stage: delivery after more than three hours of full cervical dilatation, or delivery within three hours. The primary outcome measured was the incidence of spontaneous preterm births at the subsequent delivery. RESULTS: Among 1818 women whose records were available for analysis, 416 women (22.9%) had a prolonged second stage of labour in their first delivery. Women with a prolonged second stage in their first delivery did not deliver prematurely more often in the successive delivery than those women whose second stage was not prolonged (rate of preterm birth 4.3% in the prolonged second stage group and 5.5% in the normal second stage group; P = 0.3). CONCLUSION: In our population of primiparous women with a singleton term delivery, a prolonged second stage of labour lasting more than three hours was not associated with preterm birth at their subsequent delivery.

Objectif : Déterminer si la prolongation du deuxième stade du travail exerce une influence sur l'âge gestationnel dans le cadre de l'accouchement subséquent. Méthodes : Nous avons mené une étude de cohorte rétrospective. Les renseignements cliniques ont été récupérés à partir de la McGill Obstetrical and Neonatal Database pour la période allant de janvier 2001 à février 2008. Nous nous sommes penchés sur les femmes primipares présentant une grossesse monofœtale à terme qui ont atteint le deuxième stade du travail. Ces femmes ont été réparties en deux groupes, en fonction de la durée du deuxième stade : « accouchement après plus de trois heures en présence d'une dilatation cervicale totale ¼ ou « accouchement dans un délai de trois heures ¼. L'incidence de l'accouchement préterme spontané dans le cadre de la grossesse subséquente constituait le critère d'évaluation principal. Résultats : Chez les 1 818 femmes dont les dossiers étaient disponibles aux fins de l'analyse, 416 femmes (22,9 %) avaient connu une prolongation du deuxième stade du travail au cours de leur premier accouchement. Les femmes ayant connu une prolongation du deuxième stade du travail au cours de leur première grossesse n'ont pas accouché de façon prématurée plus fréquemment dans le cadre de leur grossesse subséquente que les femmes n'ayant pas connu une prolongation du deuxième stade du travail (taux d'accouchement préterme : 4,3 % au sein du groupe « prolongation du deuxième stade du travail ¼ et 5,5 % au sein du groupe « deuxième stade normal ¼; P = 0,3). Conclusion : Au sein de notre population de femmes primipares ayant connu un accouchement à terme à la suite d'une grossesse monofœtale, une prolongation du deuxième stade du travail au-delà de trois heures n'a pas été associée à la survenue d'un accouchement préterme dans le cadre de la grossesse subséquente.

Itraconazole treatment reduces Batrachochytrium dendrobatidis prevalence and increases overwinter field survival in juvenile Cascades frogs.

The global spread of the fungal pathogen Batrachochytrium dendrobatidis (Bd) has led to widespread extirpation of amphibian populations. During an intervention aimed at stabilizing at-risk populations, we treated wild-caught Cascades frogs Rana cascadae with the antifungal drug itraconazole. In fall 2012, we collected 60 recently metamorphosed R. cascadae from 1 of the 11 remnant populations in the Cascades Mountains (CA, USA). Of these, 30 randomly selected frogs were treated with itraconazole and the other 30 frogs served as experimental controls; all were released at the capture site. Bd prevalence was low at the time of treatment and did not differ between treated frogs and controls immediately following treatment. Following release, Bd prevalence gradually increased in controls but not in treated frogs, with noticeable (but still non-significant) differences 3 wk after treatment (27% [4/15] vs. 0% [0/13]) and strong differences 5 wk after treatment (67% [8/12] vs. 13% [1/8]). We did not detect any differences in Bd prevalence and load between experimental controls and untreated wild frogs during this time period. In spring 2013, we recaptured 7 treated frogs but none of the experimental control frogs, suggesting that over-winter survival was higher for treated frogs. The itraconazole treatment did appear to reduce growth rates: treated frogs weighed 22% less than control frogs 3 wk after treatment (0.7 vs. 0.9 g) and were 9% shorter than control frogs 5 wk after treatment (18.4 vs. 20.2 mm). However, for critically small populations, increased survival of the most at-risk life stage could prevent or delay extinction. Our results show that itraconazole treatment can be effective against Bd infection in wild amphibians, and therefore the beneficial effects on survivorship may outweigh the detrimental effects on growth.

Reassessment of the normal fetal cisterna magna during gestation and an alternative approach to the definition of cisterna magna dilatation.

INTRODUCTION: Cisterna magna (CM) measurement constitutes part of the sonographic assessment of the posterior fossa. CM enlargement (ECM) is defined as a measurement exceeding 10 mm, although it has previously been noted that the CM varies in size with gestation. Existing data do not appear to reflect observations regarding CM biometry within our population and this study was therefore undertaken in order to re-evaluate CM biometry. MATERIALS AND METHODS: Data from 4,750 normal pregnancies between 15 and 32 weeks of gestation were collected and used to construct a reference range for the CM. RESULTS: Regression analysis was used to model CM across gestational age and thereby define the upper limits for normal CM measurements across gestation. The CM increases with gestation. These data suggest that a 10-mm cut-off underestimates ECM, notably in the gestational age period below 24 weeks, whilst overestimating isolated ECM beyond this. Differences in CM measurements between genders were confirmed (p < 0.0001). CONCLUSIONS: Defining ECM based upon a cut-off of 10 mm across all gestations may be inappropriate given the variation observed with gestational age. More accurate identification of fetuses with, in particular, isolated ECM may facilitate more precise evaluation of the clinical significance of this finding.

Left Ventricular Outflow Occlusion: An Alternative Approach to Late Selective Fetal Termination in Monochorionic Twin Gestations.

We report the case of a monochorionic twin gestation discordant for a mutation in the chromodomain-helicase-DNA-binding protein 7 (CHD7) gene and cerebral abnormalities consequent to an early devastating cerebrovascular event. The parents elected for selective termination given the poor prognosis for this fetus, but given socio-economic considerations wished to defer this procedure as late in gestation as possible, despite awareness of the risks and limitations of existing techniques at the end of pregnancy.  A novel technique was used to achieve selective feticide in the late-preterm period. An endovascular balloon catheter was used to occlude the left ventricular outflow and coronary circulations resulting in fetal asystole while also arresting fetoplacental flow in this fetus, immediately prior to the delivery of the healthy fetus.

The impact of in utero transfusions on perinatal outcomes in patients with alpha thalassemia major: the UCSF registry.

Alpha thalassemia major (ATM) is a hemoglobinopathy that usually results in perinatal demise if in utero transfusions (IUTs) are not performed. We established an international registry (NCT04872179) to evaluate the impact of IUTs on survival to discharge (primary outcome) as well as perinatal and neurodevelopmental secondary outcomes. Forty-nine patients were diagnosed prenatally, 11 were diagnosed postnatally, and all 11 spontaneous survivor genotypes had preserved embryonic zeta-globin levels. We compared 3 groups of patients; group 1, prenatally diagnosed and alive at hospital discharge (n = 14), group 2, prenatally diagnosed and deceased perinatally (n = 5), and group 3, postnatally diagnosed and alive at hospital discharge (n = 11). Group 1 had better outcomes than groups 2 and 3 in terms of the resolution of hydrops, delivery closer to term, shorter hospitalizations, and more frequent average or greater neurodevelopmental outcomes. Earlier IUT initiation was correlated with higher neurodevelopmental (Vineland-3) scores (r = -0.72, P = .02). Preterm delivery after IUT was seen in 3/16 (19%) patients who continued their pregnancy. When we combined our data with those from 2 published series, patients who received ≥2 IUTs had better outcomes than those with 0 to 1 IUT, including resolution of hydrops, delivery at ≥34 weeks gestation, and 5-minute appearance, pulse, grimace, activity, and respiration scores ≥7. Neurodevelopmental assessments were normal in 17/18 of the ≥2 IUT vs 5/13 of the 0 to 1 IUT group (OR 2.74; P = .01). Thus, fetal transfusions enable the survival of patients with ATM and normal neurodevelopment, even in those patients presenting with hydrops. Nondirective prenatal counseling for expectant parents should include the option of IUTs.

KNEMIDOKOPTES MITES AND THEIR EFFECTS ON THE GRIPPING POSITION OF THE FEET OF STELLER'S JAYS (CYANOCITTA STELLERI).

Steller's Jays (Cyanocitta stelleri) with swollen legs and feet resembling the signs of scaly leg have been commonly seen around Arcata, California, US. The clinical signs are thought to be caused by knemidokoptic mites, a group of parasites specialized on avian hosts. Between February 2019 and March 2020, we analyzed the long-term database of Steller's Jays collected by Humboldt State University for trends in the prevalence of signs of scaly leg, compared the gripping position in the feet of Steller's Jays with variable signs of this condition as an index of their ability to perch, identified the mites using a partial sequence of the cytochrome oxidase subunit I gene, and examined genetic distances between mites collected from different host species both sequenced in this study and from GenBank. Overall, 27% of jays recorded in the long-term database had shown signs of scaly leg. Jays with signs captured in this study had greater variability in and a reduced degree of contraction in the gripping position of their feet compared to jays without signs, suggesting that infestation may have an impact on the host's ability to perch. The cytochrome oxidase subunit I sequence (578 base pairs) from mites collected from Steller's Jays was compared to sequences from Knemidokoptes jamaicensis, Knemidokoptes derooi, and to unidentified Knemidokoptes spp. collected from different hosts. The mites from Steller's Jays were most closely related to Knemidokoptes jamaicensis but had a relatively high sequence divergence, 7.8%, supporting the possibility that the form infesting these jays may be an undescribed species.

Perinatal asphyxia from the obstetric standpoint.

Perinatal asphyxia remains one of the major causes of morbidity and mortality for term newborns. Though access to health care and birth attendants have decreased the rate, Neonatal encephalopathy (NE) has not been eliminated. Worldwide, women at socioeconomic disadvantage have the highest risk of delivering a neonate with NE. Neonates that will experience perinatal asphyxia cannot be easily identified prospectively and the intrapartum testing available is not specific enough to clearly indicate the best course of action in most cases. Despite this, training programs that aim to decrease morbidity and mortality from all causes appear to be associated with fewer cases of perinatal asphyxia. The current best approach is to support education and communication for all people involved in the care of birthing women. Ideally, new technology will address identification of the fetus likely to be affected or the fetus who is beginning to experience injury in advance of delivery.

Infective endocarditis in a dog and the phylogenetic relationship of the associated "Bartonella rochalimae" strain with isolates from dogs, gray foxes, and a human.

The first case of canine endocarditis caused by "Bartonella rochalimae" is reported. By PCR-restriction fragment length polymorphism, sequence, and phylogenetic analyses, Bartonella isolates from a dog with endocarditis, 22 gray foxes, and three dogs, described as B. clarridgeiae like, were confirmed to belong to the new species "B. rochalimae," suggesting canids as the natural reservoir.

Ecology of Anaplasma phagocytophilum infection in gray foxes (Urocyon cinereoargenteus) in northwestern California.

Although granulocytic anaplasmosis, caused by infection of Anaplasma phagocytophilum, is an emerging human and domestic animal disease, the ecology and natural history of the parasite is not well understood. Gray foxes (Urocyon cinereoargenteus) are relatively common, occasionally peri-urban mesocarnivores whose geographic distribution overlaps the reported distribution of granulocytic anaplasmosis in humans and domestic animals in North America. We evaluated the potential of foxes as hosts and reservoirs of A. phagocytophilum in both urban and backcountry habitats of the Hoopa Valley Indian Reservation, Humboldt County, California, USA. We trapped 54 individual foxes and had 16 recaptures for a total of 70 fox samples between June 2003 and October 2004 in delineated urban and backcountry zones. We collected 296 adult and 145 nymphal ticks from the 70 captured foxes including 193 Ixodes pacificus, 149 Ixodes texanus, 98 Dermacentor variabilis, and one Dermacentor occidentalis. There were seasonal differences in tick intensities, with most I. pacificus adults occurring in winter and spring (P < 0.001), most I. texanus nymphs in spring (P = 0.03), and most D. variabilis adults in spring and summer (P = 0.01). Thirty-six (51%) of the 70 fox sera had antibodies against A. phagocytophilum, with a higher (P = 0.24) prevalence in backcountry foxes (16 of 23) than in urban-zone foxes (12 of 31). Six (9%) of 70 fox samples were polymerase chain reaction-positive for A. phagocytophilum. Twenty-eight (31%) of 90 domestic dogs sampled from vaccine clinics within the study area were seropositive for A. phagocytophilum. There was a significant difference in prevalence between dogs and backcountry foxes (70%), but no differences were found between dogs and urban foxes (39%). We propose that gray foxes are a good sentinel species for A. phagocytophilum infections in northwestern California.

Recent advances in the antepartum management of diabetes.

Gestational and pre-gestational diabetes are frequent problems encountered in obstetrical practice and their complications may influence both the mother (such as hypertension, pre-eclampsia, increased caesarean rates) and the foetus (such as macrosomia, shoulder dystocia, respiratory distress, hypoglycaemia, or childhood obesity and diabetes). Given the important implications for mothers and their offspring, screening and appropriate management of diabetes during pregnancy are essential. This is a review of articles published between 2015 and 2018 on Medline via Ovid that focus on advances in the management of diabetes in pregnancy. Recent data have concentrated predominantly on optimising glycaemic control, which is key for minimising the burden of maternal and foetal complications. Lifestyle changes, notably physical exercise and diet adjustments, appear to have beneficial effects. However, data are inconclusive with respect to which diet and form of exercise provide optimal benefits. Oral glycaemic agents-in particular, metformin-are gaining acceptance as more data indicating their long-term safety for the foetus and newborn emerge. Recent reviews present inconclusive data on the efficacy and safety of insulin analogues. New technologies such as continuous insulin pumps for type 1 diabetes and telemedicine-guided management of diabetes are significantly appreciated by patients and represent promising clinical tools. There are few new data addressing the areas of antenatal foetal surveillance, the timing and need for induction of delivery, and the indications for planned caesarean section birth.

Anaplasma phagocytophilum infection in small mammal hosts of Ixodes ticks, western United States.

A total of 2,121 small mammals in California were assessed for Anaplasma phagocytophilum from 2006 through 2008. Odds ratios were >1 for 4 sciurids species and dusky-footed woodrats. High seroprevalence was observed in northern sites. Ten tick species were identified. Heavily infested rodent species included meadow voles, woodrats, deer mice, and redwood chipmunks.

Differential exposure to Anaplasma phagocytophilum in rodent species in northern California.

Anaplasma phagocytophilum is a zoonotic tick-borne rickettsial pathogen that causes granulocytic anaplasmosis (GA) in humans, horses, and dogs. In California, dusky-footed woodrats (Neotoma fuscipes) are a putative reservoir host, and Ixodes pacificus is a vector for transmission from rodents to humans, dogs, and horses. Cases are clustered in coastal and Sierra Nevada foothill regions, but not necessarily in proximity to infected woodrats. This study was designed to compare exposures and active infections of A. phagocytophilum in multiple rodents at a fine spatial scale in a hyperenzootic area and to evaluate the spatial clustering of infections. Of 331 rodents, the seroprevalence was 14.5%, with 60% in tree squirrels (Sciurus griseus and Tamiasciurus douglasii), 29% in woodrats, 14% in flying squirrels (Glaucomys sabrinus), and 5% in chipmunks (Tamias senex). No seropositive ground squirrels (Spermophilus beecheyi) were detected. The seroprevalence was significantly higher west of the Trinity River (23.1%) than east (11.8%) of the river. One Douglas squirrel and one western gray squirrel were polymerase chain reaction (PCR) positive. There was more spatial clustering among seropositive animals compared with all animals tested across the spatial scales evaluated, and this clustering was significantly greater than expected by chance alone. A significant cluster of 24 seropositive animals was found west of the Trinity River, with a population of 56 animals considered within the 50% population-at-risk, and a radius of 362.8 meters. The diversity of cricetine and sciurid rodents infected suggests that squirrels and chipmunks may be underappreciated contributors to A. phagocytophilum ecology in the western United States. The spatial clustering of exposed animals suggests interesting underlying spatially heterogeneous environmental variables that could facilitate the persistence of A. phagocytophilum in nature.