Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southwestern Michigan.

Amblyomma americanum (Linnaeus) (Acari: Ixodidae) (lone star tick) is an aggressive, generalist parasite that vectors numerous important human and animal pathogens. In recent decades its geographic range has expanded northwards from endemic regions in the southeastern and southcentral United States. In 2019 five questing A. americanum ticks, comprising two life stages were detected at one site in southwestern Michigan, satisfying one CDC criterium for an established population for the first time in recent history in the state. To better characterize the extent of emerging A. americanum, we conducted active surveillance (i.e., drag sampling) in summer 2020 throughout Michigan's southern counties and detected one adult A. americanum from each of six widespread sites, including where they had been detected in 2019. A larger established population was identified at another site in Berrien County, which yielded 691 A. americanum comprising three life stages, and questing phenologies here were similar to that reported for other endemic regions. Statewide surveillance in 2021 revealed no A. americanum outside of Berrien County, but establishment criteria were met again at the two sites where established populations were first detected respectively in 2019 and 2020. These observations may represent the successful invasion of A. americanum into Michigan. Data from passive (1999-2020) and active surveillance (2004-2021) efforts, including a domestic animal sentinel program (2015-2018), are reported to provide context for this nascent invasion. Continued active surveillance is needed to help inform the public, medical professionals, and public health officials of the health risks associated with this vector.

Acquisition of Borrelia burgdorferi Infection by Larval Ixodes scapularis (Acari: Ixodidae) Associated With Engorgement Measures.

Measuring rates of acquisition of the Lyme disease pathogen, Borrelia burgdorferi sensu lato Johnson, Schmid, Hyde, Steigerwalt & Brenner, by the larval stage of Ixodes scapularis Say is a useful tool for xenodiagnoses of B. burgdorferi in vertebrate hosts. In the nymphal and adult stages of I. scapularis, the duration of attachment to hosts has been shown to predict both body engorgement during blood feeding and the timing of infection with B. burgdorferi. However, these relationships have not been established for the larval stage of I. scapularis. We sought to establish the relationship between body size during engorgement of larval I. scapularis placed on B. burgdorferi-infected, white-footed mice (Peromyscus leucopus Rafinesque) and the presence or absence of infection in larvae sampled from hosts over time. Body size, time, and their interaction were the best predictors of larval infection with B. burgdorferi. We found that infected larvae showed significantly greater engorgement than uninfected larvae as early as 24 h after placement on a host. These findings may suggest that infection with B. burgdorferi affects the larval feeding process. Alternatively, larvae that engorge more rapidly on hosts may acquire infections faster. Knowledge of these relationships can be applied to improve effective xenodiagnosis of B. burgdorferi in white-footed mice. Further, these findings shed light on vector-pathogen-host interactions during an understudied part of the Lyme disease transmission cycle.

Reverse line blot probe design and polymerase chain reaction optimization for bloodmeal analysis of ticks from the eastern United States.

Determining the host preference of vector ticks is vital to elucidating the eco-epidemiology of the diseases they spread. Detachment of ticks from captured hosts can provide evidence of feeding on those host species, but only for those species that are feasible to capture. Recently developed, highly sensitive molecular assays show great promise in allowing host selection to be determined from minute traces of host DNA that persist in recently molted ticks. Using methods developed in Europe as a starting-point, we designed 12S rDNA mitochondrial gene probes suitable for use in a reverse line blot (RLB) assay of ticks feeding on common host species in the eastern United States. This is the first study to use the 12S mitochondrial gene in a RLB bloodmeal assay in North America. The assay combines conventional PCR with a biotin-labeled primer and reverse line blots that can be stripped and rehybridized up to 20 times, making the method less expensive and more straightforward to interpret than previous methods of tick bloodmeal identification. Probes were designed that target the species, genus, genus group, family, order, or class of eight reptile, 13 birds, and 32 mammal hosts. After optimization, the RLB assay correctly identified the current hostspecies for 99% of ticks [Amblyomma americanum (L.) and eight other ixodid tick species] collected directly from known hosts. The method identified previous-host DNA for approximately half of all questing ticks assayed. Multiple bloodmeal determinations were obtained in some instances from feeding and questing ticks; this pattern is consistent with previous RLB studies but requires further investigation. Development of this probe library, suitable for eastern U.S. ecosystems, opens new avenues for eco-epidemiological investigations of this region's tick-host systems.

High-prevalence Borrelia miyamotoi infection among [corrected] wild turkeys (Meleagris gallopavo) in Tennessee.

During spring and fall 2009, 60 wild turkeys (Meleagris gallopavo) harvested by Tennessee hunters were surveyed for Borrelia spp. by sampling their blood, tissue, and attached ticks. In both seasons, 70% of turkeys were infested with juvenile Amblyomma americanum; one spring turkey hosted an adult female Ixodes brunneus. Polymerase chain reaction assays followed by DNA sequencing indicated that 58% of the turkeys were positive for the spirochete Borrelia miyamotoi, with tissue testing positive more frequently than blood (P = 0.015). Sequencing of the 16S-23S rRNA intergenic spacer indicated > or = 99% similarity to previously published sequences of the North American strain of this spirochete. Positive turkeys were present in both seasons and from all seven middle Tennessee counties sampled. No ticks from the turkeys tested positive for any Borrelia spp. This is the first report of B. miyamotoi in birds; the transmission pathways and epidemiological significance of this high-prevalence spirochetal infection remain uncertain.

Biodiversity and Lyme disease: dilution or amplification?

Reduced Lyme disease risk by the 'dilution effect' is often cited as an example of biodiversity providing 'ecosystem services' to public health. Using a mechanistic model we investigated how transmission of the Lyme disease agent, Borrelia burgdorferi, by Ixodes scapularis ticks amongst highly efficient reservoir mice is affected by varying the abundance of a less efficient reservoir host. Simulations indicated either amplification or dilution may occur, with the outcome depending precisely on mechanisms of competition, host contact rates with ticks, and acquired host resistance to ticks. Quantifying these mechanisms will be crucial to predicting how biodiversity affects Lyme disease risk.

Management of hilar cholangiocarcinoma: comparison of an American and a Japanese experience.

OBJECTIVE: To compare the experience and outcome in the management of hilar cholangiocarcinoma at one American and one Japanese medical center. SUMMARY BACKGROUND DATA: Controversies surround the issues of extent of resection for hilar cholangiocarcinoma and whether the histopathology of such cancers are similar between patients treated in America and in Japan. METHODS: Records were reviewed of 100 patients treated between 1980 and 1995 at the Lahey Clinic in the United States, and of 155 patients treated between 1977 and 1995 at Nagoya University Hospital in Japan. Selected pathologic slides of resected cancers were exchanged between the two institutions and reviewed for diagnostic concordance. RESULTS: In the Lahey cohort, there were 25 resections, 53 cases of surgical exploration with biliary bypass or intubation, and 22 cases of percutaneous transhepatic biliary drainage or endoscopic biliary drainage without surgery. In the Nagoya cohort, the respective figures were 122, 10, and 23. The overall 5-year survival rate of all patients treated (surgical and nonsurgical) during the study periods was 7% in the Lahey cohort and 16% in the Nagoya cohort. The overall 10-year survival rates were 0% and 12%, respectively. In patients who underwent resection with negative margins, the 5- and 10-year survival rates were 43% and 0% for the Lahey cohort and 25% and 18% for the Nagoya cohort. The surgical death rate for patients undergoing resection was 4% for Lahey patients and 8% for Nagoya patients. Of the patients who underwent resection, en bloc caudate lobectomy was performed in 8% of the Lahey patients and 89% of the Nagoya patients. Histopathologic examination of resected cancers showed that the Nagoya patients had a higher stage of disease than the Lahey patients. CONCLUSIONS: In both Lahey and Nagoya patients, survival was most favorable when resection of hilar cholangiocarcinoma was accomplished with margin-negative resections. Combined bile duct and liver resection with caudate lobectomy contributed to a higher margin-negative resection rate in the Nagoya cohort.

Hepatic malignancies.

The battle against malignancies of the liver is far from over, although tremendous strides have been made in the past decade, such as improved diagnostic capabilities, safe surgical resection, availability of safe nonsurgical ablative modalities, multimodality therapy, and aggressive approach to recurrent disease. Even after the best attempts at curative treatment, recurrence of primary and secondary malignancies of the liver continues to be the cause of demise for more than 70% of treated patients. The battle continues in the laboratories, where investigations are focused on delineating the pathophysiology of cancer on the molecular and genetic levels and mapping the patterns of cancer emergence and spread. The new millennium holds promise for formulating therapies that may improve disease-free survival for patients with malignancies of the liver.

Patterns of p53 mutations in squamous cell carcinoma of the lung. Acquisition at a relatively early age.

Squamous cell carcinoma (SQCC) of the lung is thought to arise after the accumulation of multiple mutations, including p53. To better characterize when p53 mutations are acquired, 37 SQCC of the lung were examined by polymerase chain reaction and single-strand conformation polymorphism analysis. Somatic p53 mutations were detected in nine tumors (24.3%). There were no significant differences in the stage, sex, or race between patients with or without p53 mutations. However, the patients with SQCC and p53 mutations were significantly (P = 0.0006) younger (mean age, 54.3 years) compared with patients without p53 mutations (mean age, 65). The topographical tissue distributions of the p53 mutations were examined by selective ultraviolet radiation fractionation. In all nine cases, the specific p53 mutant alleles were homogeneously present throughout the primary tumors, in all three examples with in situ carcinoma, and in all four cases with metastases. In one case, squamous metaplasia contiguous with the primary tumor also contained the same p53 mutation. Normal or hyperplastic and metaplastic or dysplastic epithelium not contiguous with the primary tumors lacked the specific p53 mutations. These findings suggest that p53 mutations are commonly acquired at a relatively early age, before the bulk of clonal expansion, and usually persist throughout the progression of SQCC of the lung.

Biliary reconstruction.

The success of the initial repair after bile duct injury is critical to the long-term patency and function of the biliary tract. Dissection of the hilar plate, obtaining adequate width of the hepatic duct opening, and accurate mucosa-to-mucosa anastomosis are essential to achieving satisfactory reconstruction of the biliary tract. The plan of treatment for bile duct injuries should be tailored to the individual patient based on the type, level, and extent of the injury, the timing of diagnosis, the overall status of the patient, and the available expertise. The goal of therapy is not necessarily to avoid surgery but to achieve the best long-term results in the most cost-effective manner and with the least morbidity and mortality. A coordinated multidisciplinary approach to the diagnosis and treatment of patients with biliary injuries is now the standard.

Trends in morbidity and mortality of hepatic resection for malignancy. A matched comparative analysis.

OBJECTIVE: The authors define more clearly the trends in morbidity and mortality after hepatic resection for malignant disease in matched patient groups during two discrete time periods. SUMMARY BACKGROUND DATA: Recent reports have shown improvement in operative morbidity and mortality associated with hepatic resection; however, results often included resections for benign disease and trauma. Furthermore, specific factors contributing to the improvement in operative risks between the last two decades have not been defined. METHODS: A retrospective matched comparative analysis was conducted of patients with primary and metastatic hepatic malignancy resected with curative intent between two periods (1976 to 1980 and 1986 to 1990). Eighty-one patients met our inclusion criteria in the early period; this group was matched with 81 patients from the latter period by the following four parameters: age, gender, type of malignant disease, and extent of resection. Records of these two patient groups were abstracted for clinical presentation, co-morbid factors, operative techniques, and perioperative morbidity and mortality. RESULTS: The authors found a significant decrease in operative morbidity, median perioperative transfusion, and length of hospital stay in the latter period (1986 to 1990). The incidence of postoperative subphrenic abscess and intra-abdominal hemorrhage was significantly lower during this period. Operative mortality rate was similar for both periods, 4.9% and 1.2%, respectively (p > 0.05). CONCLUSION: Hepatic resection for malignant disease currently can be performed with a low morbidity and mortality in the hands of trained and experienced hepatic surgeons; operative risks of hepatic resection should not deter its application in the treatment of primary and metastatic malignant disease of the liver.

Pylorus-preserving pancreatoduodenectomy. Is it an adequate cancer operation.

OBJECTIVE: To assess the adequacy of pylorus-preserving pancreatoduodenectomy (PPPD) as a definitive surgical treatment for primary malignant diseases of the periampullary region. DESIGN: Retrospective review of the clinical records of patients undergoing PPPD for malignant diseases of the periampullary region. Median and 5-year actuarial survival by type and stage of cancer were determined. Survival data from this study were compared with those of patients undergoing a conventional Whipple operation. SETTING: Lahey Clinic, Burlington, Mass. STUDY PARTICIPANTS: One hundred six patients undergoing PPPD for primary malignant disease of the periampullary region between November 1979 and June 1992. INTERVENTION: Pylorus-preserving pancreatoduodenectomy was performed with curative intent in the 106 patients. Ninety-five patients underwent proximal pancreatectomy; 11 patients, total pancreatectomy. Resection of the portal vein was performed in 10 patients. MAIN OUTCOME MEASURE: Long-term survival following PPPD was analyzed with respect to the type and stage of cancer. Median follow-up was 30 months (range, 6 to 156 months). RESULTS: Five-year actuarial survival rates were 45.4% for patients with ampullary adenocarcinoma; 6.6%, with pancreatic ductal adenocarcinoma; 33.3%, with distal bile duct adenocarcinoma; 75%, with pancreatic islet cell adenocarcinoma; and 0%, with pancreatic cystadenocarcinoma. An early cancer stage was associated with more favorable survival for ampullary and distal bile duct adenocarcinomas. For pancreatic ductal adenocarcinoma only, tumors less than 2 cm were associated with better survival. Duodenal resection margins were free of disease in all patients, while peripancreatic and retroperitoneal extension of the tumor was found in 20%. CONCLUSION: For patients with periampullary malignant disease, long-term survival following PPPD is similar to that following a conventional Whipple operation. The potential benefits of hemigastrectomy with perigastric lymphadenectomy are frequently obviated by the presence of positive margins and lymph nodes elsewhere, ie, in the retroperitoneum. We advocate PPPD as the procedure of choice for locally resectable malignant disease of the periampullary region, provided the duodenal margin is viable and tumor free.

Hepatoma registry of the Western world. Repeat Hepatic Resection Registry.

The western HCC registry comprised data from 322 patients who underwent hepatic resection for HCC over a 50-year period. The majority of patients had lesions > 4 cm and were symptomatic at presentation. Lesions were mostly unicentric. Cirrhosis was not a prevalent problem, unlike the East. In the most recent decade, 1980-1989, we noted a significant decrease in operative mortality from 19% to 10% overall, and 15% to 4% in the noncirrhotic group. We identified four variables that resulted in poorer postresectional outcome: cirrhosis, regional nodal disease, multicentric disease, and tumor-free resectional margin < 1 cm. Although these factors are associated with a poorer outcome after resection, whether they should serve as contraindications to surgery should be determined by individual surgeons, taking into account the patient's overall status, concomitant risk factors, and treatment objectives.

Resection of hepatic metastases from colorectal carcinoma. The registry data.

When liver metastases from colorectal carcinoma are detected, the surgeon must decide whether or not the patient is a candidate for resection. Even though long-term survival after resection is far from optimal, the relegation of patients to nonresective treatment means denying them the only chance for cure currently available. Better understanding of liver anatomy and improvement in resection techniques have decreased the morbidity and mortality. The RHM and the GITSG reports have better defined the prognostic factors for resections of colorectal liver metastases and allowed for a better understanding of the indications for resection. During the last decades, liver resection has been extended to older patients, patients with multiple liver lesions, and patients with larger solitary metastases. At the same time, anatomic rather than wedge resections are more common, and it is preferable to perform the colon and liver resection at different stages. The end result has been a marked increase in the number of hepatic resections performed for colorectal liver metastases during the last two decades.

Pouchogram: predictor of clinical outcome following ileal pouch-anal anastomosis.

UNLABELLED: Among 914 patients undergoing ileal pouch-anal anastomosis (IPAA) between January 1981 and June 1989, 463 (51 percent) had a pouchogram (meglumine diatrizoate [Gastrografin; E.R. Squibb & Sons, Inc., Princeton, NJ] enema) to assess anastomosis and ileal pouch integrity before closure of the ileostomy. The aim was to determine whether a pouchogram was useful in predicting clinical outcome. RESULTS: Abnormal findings were present in 74 patients (16 percent). These included anastomotic and pouch leaks and anstomotic strictures. Pouchograms were normal in the remaining 389 patients (84 percent). The incidence of significant anastomotic stricturing requiring dilatation under anesthesia was much higher in the abnormal than in the normal pouchogram group (33 percent vs. 4 percent, respectively; P less than 0.001). More significantly, an abnormal pouchogram was associated with an overall long-term failure rate of 23 percent, compared with 6 percent for a normal pouchogram (P less than 0.001). CONCLUSION: Abnormal findings in a pouchogram prior to ileostomy closure indicated those patients at high risk of long-term complications following IPAA.