Can risk area designation help increase vaccination coverage for Tick-Borne Encephalitis? Evidence from German claims data.

BACKGROUND AND OBJECTIVES: Although vaccine preventable, the incidence of tick-borne encephalitis (TBE) increased in Germany from 2001 to 2021 by on average 2% each year, with a peak of more than 700 TBE infections documented in 2020. TBE-risk areas, as designated by district based on incidence of human cases, expanded north- and northeastward, present in 11 of the 16 Federal States as of 2022. Using claims data from a German statutory health insurance in the Federal States of Saxony and Thuringia (AOK PLUS), we aimed to assess whether official assignment of a district to a risk area had an impact on vaccination rates in Germany. METHODS: The data covered the period from 01/01/2010 to 31/12/2018 and included information on vaccine administrations from outpatient physicians. Yearly incident vaccination rates were reported overall and by district. To investigate the association between a new designation of an incident TBE-risk area and vaccination rates, a difference-in-difference analysis was conducted. RESULTS: Overall, the incident vaccination rates increased from 6.2 to 9.5 per 1,000 person-years between 2012 and 2018, with a peak of 12.2 in 2015. While districts that had been risk-areas for the whole study period had always a higher vaccination rate compared to districts that were never categorized as risk areas, the increase between 2012 and 2018 was comparable in the two groups (3.0 and 3.2 per 1,000 person-years, respectively). In contrast, districts that were newly designated risk districts during the study period experienced a significantly larger increase in vaccination rates, going from 5.8 to 14.7 per 1,000 person-years between 2012 and 2018, with a peak of 19.6 in 2015. CONCLUSION: The results suggest that the new designation of a district as risk area has a significant positive impact on vaccination rates, which is strongest immediately after designation of risk area.

Long-term cost and complications of surgery in patients with ulcerative colitis: a claims data analysis.

OBJECTIVES: Use claims data to assess healthcare resource utilization (HCRU) and cost for patients with ulcerative colitis (UC) who had surgery and patients who did not. METHODS: UC patients from a German health insurance were included between 01/01/2010-31/12/2017. Patients with proctocolectomy or colectomy between 01/07/2010 and 31/12/2014 were identified, and surgery date was set as index. For patients with IPAA, the last surgery in the 6 months was taken as index. Non-surgery patients received random index. After propensity score matching, UC-related HCRU and cost were observed for three years post-index. RESULTS: Of 21,392 UC patients, 85 underwent surgery and 2655 did not. After matching, 76 were included in the surgery group and 114 in the non-surgery group. Matched cohorts did not differ in baseline characteristics and mortality rates where high in both groups (21.1% and 29.0%, respectively). The percentage of patients with at least one hospitalization in the follow-up period was higher in the surgery (53.9%) compared to the non-surgery group (25.4%, p<0.001). In contrast, the number of outpatient prescriptions of UC-related drugs in the non-surgery group (11.2) was almost twice as large as in the surgery group (5.8, p<0.001). Hospitalization cost was 4.6 times higher in the surgery (1955.5€) than in the non-surgery group (419.6€, p<0.001). Medication cost was three times higher in the non-surgery group (6519€) compared to the surgery group (2151.7€, p<0.001). CONCLUSIONS: Based on hospitalizations, outpatient visits, and medical treatment, results show a considerable patient burden in UC from surgery complications or disease exacerbation in case of colectomy.

Indicators of active disease and steroid dependency in patients with inflammatory bowel diseases not treated with biologics in a German real-world-setting.

BACKGROUND AND AIMS: While a minority of inflammatory bowel disease (IBD) patients receives biologics in Germany, little is known about therapeutic needs of patients receiving non-biologic therapies. This study aimed to identify indicators of active disease/steroid dependency in patients with moderate to severe Crohn's disease (CD) and ulcerative colitis (UC) treated with conventional therapies and to describe health care resource use (HCRU)/cost. METHODS: CD/UC patients treated with immunosuppressants (IS) and/or systemic or locally acting oral corticosteroids (CS) were identified in German claims data (2013-2017) and followed for 12 months post-therapy start. Indicators of active disease/steroid dependency during follow-up period were (i) ≥ 2 prescriptions of CS (sensitivity ≥ 4) or (ii) ≥ 1 IBD-related surgery or (iii) > 7 days IBD-related hospitalization(s). RESULTS: Of 9871 included IBD patients (5170 CD, 4701 UC), 25.7%/19.9% (CD/UC) received ≥ 2 prescriptions of CS (sensitivity, 17.4%/15.7%) (i), 3.2% experienced IBD-related surgeries (ii), and 2.5% > 7 days of hospitalizations (iii). Altogether, 44.4% had indicators of active disease/steroid dependency (sensitivity, 23.9%). Among patients with active disease/steroid dependency, 78.0% received CS monotherapy at baseline. Of these, 89.6% received a CS monotherapy in the follow-up period, too. Proportionally, fewer patients with CS monotherapy (57.4%) than IS therapy (91.0%) visited a specialist. HCRU/cost per patient year was significantly higher in patients with than without active disease/steroid dependency. CONCLUSIONS: A substantial percentage of biologic-naïve IBD patients suffers from active disease/steroid dependency. The majority receives a monotherapy with systemic CS. Referral to gastroenterologists for treatment optimization is recommended, also because active disease/steroid dependency is associated with increased HCRU/cost.

Treatment of age-related neovascular macular degeneration: the patient's perspective.

OBJECTIVES: The aim of this study was to assess patients' views and expectations with regard to neovascular age-related macular degeneration (nAMD) and intravitreal anti-VEGF therapy (IVT). METHODS: We conducted a multicenter, non-interventional, prospective cohort study including nAMD patients treated with IVT in Germany. Patients with at least one IVT before study enrollment and aged ≥50 years were included. Three telephone interviews were conducted during a 12-month observational period. Here, patient's beliefs/expectations with regard to the nAMD disease and the IVT treatment were discussed. Only patients who completed all three phone interviews were included in the analyses. We used a two-step cluster analysis to identify patient clusters regarding specific patient attitudes towards nAMD and its treatment. RESULTS: Three hundred and thirty-two patients completed all interviews (mean age of 76.4 ± 7.2 years, 59.0% women). Out of these, 57.8% acknowledged that they needed general assistance in daily life, while 77.4% stated being able to attend general medical appointments on their own. However, 64.7% needed a driver or an accompanying person to attend their IVT appointments. In addition, 3.9% of the patients were afraid of IVT side effects. Also, 87.3% and 43.1% of the patients could name their disease or the anti-VEGF drug administered, respectively. More than three-quarters of the patients (83.1%) were aware of possible consequences of nAMD by stating vision loss or blindness, but only 16.6% knew that nAMD is a chronic disease. Generally, patients were optimistic: 70.2%, 5.1% and 13.0% of them expected stable visual acuity (VA), a significant improvement or expected worsening of VA in the next year, respectively. Almost two thirds of patients who provided their therapy expectations (47.0%) anticipated fewer injections/discontinuation of IVT. We identified five patient clusters differing significantly from each other with regard to four variables: being afraid of IVT, nAMD disease awareness, optimism with regard to effectiveness of IVT, and nAMD disease and treatment knowledge. CONCLUSIONS: Only a minority of patients is aware of the chronic nature of nAMD. To motivate patients to accept a life-long IVT treatment, physicians and caregivers must know that there exist different patient types with significant differences in communication needs.

Evolutionary bottlenecks in brackish water habitats drive the colonization of fresh water by stingrays.

Species richness in freshwater bony fishes depends on two main processes: the transition into and the diversification within freshwater habitats. In contrast to bony fishes, only few cartilaginous fishes, mostly stingrays (Myliobatoidei), were able to colonize fresh water. Respective transition processes have been mainly assessed from a physiological and morphological perspective, indicating that the freshwater lifestyle is strongly limited by the ability to perform osmoregulatory adaptations. However, the transition history and the effect of physiological constraints on the diversification in stingrays remain poorly understood. Herein, we estimated the geographic pathways of freshwater colonization and inferred the mode of habitat transitions. Further, we assessed habitat-related speciation rates in a time-calibrated phylogenetic framework to understand factors driving the transition of stingrays into and the diversification within fresh water. Using South American and Southeast Asian freshwater taxa as model organisms, we found one independent freshwater colonization event by stingrays in South America and at least three in Southeast Asia. We revealed that vicariant processes most likely caused freshwater transition during the time of major marine incursions. The habitat transition rates indicate that brackish water species switch preferably back into marine than forth into freshwater habitats. Moreover, our results showed significantly lower diversification rates in brackish water lineages, whereas freshwater and marine lineages exhibit similar rates. Thus, brackish water habitats may have functioned as evolutionary bottlenecks for the colonization of fresh water by stingrays, probably because of the higher variability of environmental conditions in brackish water.

[Incidence and prevalence of type 2 diabetes mellitus in Germany: an analysis based on 5.43 million patients]. / Inzidenz und Prävalenz von Diabetes mellitus Typ 2 in Deutschland.

BACKGROUND AND OBJECTIVE: Based on claims-data of 5.43 million members of a large German statutory health insurance fund in 2008 (Techniker Krankenkasse), the aim of this contribution is to update and more precisely quantify age- and gender-specific prevalence and incidence of type 2 diabetes mellitus (T2DM) in a German setting. METHODS: A patient was classified as T2DM prevalent if he or she had received at least two outpatient diagnoses of T2DM in two different quarters of the year and/or had received at least one T2DM diagnosis during inpatient treatment between 01/01/2006 and 12/31/2008. A patient was considered to have had new onset T2DM in 2008 under one of three conditions: 1. no diagnosis of T2DM in 2006 and 2007, 2. no presripction of oral antidiabetics in 2006 and 2007, 3. either one inpatient or two outpatient diagnoses of T2DM conducted in two different quarters of 2008 or one outpatient T2DM diagnosis in 2006/07 when the second diagnosis was made in 2008. RESULTS: A total of 254,524 patients had T2DM. Compared to the total membership of the medical insurance fund, the prevalence of T2DM was 4.69 %. The average age was 64.8 years, and 66.37 % were male. The incidence of T2DM in our sample was 2.814 cases per 1,000 person-years in men and 1.690 cases in 1,000 person-years in women. Based on our sample and on official population data, 4,704,585 patients (5.75 %) in Germany would be T2DM prevalent in 2009. The number of incident T2DM cases would amount to 215,746 patients (0.264 %). CONCLUSIONS: T2DM is one of the most common chronic diseases in Germany. The expected demographic changes in Germany will increase the burden on the German health system caused by T2DM.

[Sledge versus bicondylar surface treatment in the endoprosthetic therapy for unicompartmental knee arthrtitis--a comparative cost analysis]. / Kostenvergleichskalkulation der Schlitten- vs. bikondylären Oberflächenversorgung am Kniegelenk.

BACKGROUND: The G-DRG system reimburses sledge endoprosthetic implantations (UKA) at a much lower rate than surface replacements (TKA), at significantly different cost weights (CW). Therefore, when only G-DRG payments are considered, the complete endoprosthesis implantation produces higher gains. An orientation on these revenues alone, however, does not provide the basis for an economically sound decision-making process. The aim of this study is to present a comparison of the variable costs of the two procedures. MATERIAL AND METHODS: The mean cost and performance data of 28 Endo-Model UKA implantations and of 85 NexGen CR TKA replacements were compared with each other in 2007. RESULTS: From the perspective of the hospital, when the correct medical indication is present, UKA treatment is of greater economic advantage. In this way the total unit contribution margin can be improved, and although the relative weighting is comparatively low, the costs are significantly lower than in a comparative analysis of the TKA. CONCLUSION: For the desired maximisation of the unit contribution margin, assuming that it is the proper medical indication, the recommendation for the hospital would be implantation of the UKA. Considered from the economic perspective of gains and costs, the assumption that a TKA would be advantageous could not be confirmed in the present study.

[Patient pathways in thrombosis prophylaxis after hip and knee replacement surgery : results of a survey]. / Patientenpfade in der Thromboseprophylaxe nach Hüft- und Kniegelenkersatz : Ergebnisse eines Surveys.

A key element of patient care after hip and knee replacement is medication-based thrombosis prophylaxis. Due to decreasing lengths of acute hospital stays the question arises to what extent outpatients are taking responsibility thrombosis prophylaxis (patient pathway analysis).To analyze patient pathways a telephone survey of 668 patients was conducted. On average patients were interviewed 38 days following surgery with a focus on low molecular weight heparins. The analysis showed that nearly 90% of patients need to carry out thrombosis prophylaxis in an outpatient or home environment for at least 1 day and for 47.2% of patients a linking period between acute and rehabilitation stay is relevant. The obviously existing quantitative importance of outpatient thrombosis prophylaxis is also reflected by its duration and 45.7% of interviewed patients needed at least 5 days of outpatient prophylaxis.Outpatient thrombosis prophylaxis clearly makes high demands on the patients, in particular when combined with the task of administering complex forms of injections. Those involved in inpatient and outpatient provision of care should not assume that all patients carry out the necessary prophylaxis at the required level of reliability. On the contrary initial evidence shows that the non-adherence of patients during ambulatory thrombosis prophylaxis presents a genuine challenge to care providers.

Pleistocene phylogeography and phylogenetic concordance in cold-adapted spring snails (Bythinella spp.).

Previous studies on Pleistocene phylogeography of European taxa are biased towards (i) vertebrates, (ii) terrestrial taxa, (iii) single species, and (iv) taxa that survived the Pleistocene in southern refugia. Relatively little is known about whether evolutionary patterns of vertebrate and terrestrial taxa are also applicable to freshwater invertebrates, whether cold-adapted freshwater species could survive in extensive permafrost areas without retreating into refugia, and whether Pleistocene phylogeographical patterns are influenced by phylogeny. Here, the widespread and species-rich European spring snail genus Bythinella Moquin-Tandon, 1856 is utilized in an attempt to mitigate this bias. These strongly cold-adapted freshwater animals mostly occur in springs--highly isolated habitats that are relatively unaffected by anthropogenic influences. Phylogenetic and phylogeographical analyses based on mitochondrial DNA and nuclear DNA sequence data were conducted in 458 specimens from 142 populations occurring throughout Europe. The study provides evidence that most Bythinella spp. survived the Pleistocene in restricted northern glacial refugia that largely correspond to refugia previously recognized for other European biota. However, survival of Bythinella spp. in extensive permafrost areas outside of refugia can likely be rejected. Low dispersal ability and the isolation and fragmentation of spring habitats, as well as the distribution of perennial springs within permafrost regions, may account for this result. Tests involving a total of 29 nominal species showed that phylogenetically closely related Bythinella species did not occupy similar refugia. This lack of phylogenetic concordance could possibly be explained by the stochasticity of survival and dispersal in spring snails.

The costs of heparin-induced thrombocytopenia: a patient-based cost of illness analysis.

UNLABELLED: SUMMARY BACKGROUND AND OBJECTIVES: Due to the complexity of heparin-induced thrombocytopenia (HIT), currently available cost analyses are rough estimates. The objectives of this study were quantification of costs involved in HIT and identification of main cost drivers based on a patient-oriented approach. METHODS: Patients diagnosed with HIT (1995-2004, University-hospital Greifswald, Germany) based on a positive functional assay (HIPA test) were retrieved from the laboratory records and scored (4T-score) by two medical experts using the patient file. For cost of illness analysis, predefined HIT-relevant cost parameters (medication costs, prolonged in-hospital stay, diagnostic and therapeutic interventions, laboratory tests, blood transfusions) were retrieved from the patient files. The data were analysed by linear regression estimates with the log of costs and a gamma regression model. Mean length of stay data of non-HIT patients were obtained from the German Federal Statistical Office, adjusted for patient characteristics, comorbidities and year of treatment. Hospital costs were provided by the controlling department. RESULTS AND CONCLUSIONS: One hundred and thirty HIT cases with a 4T-score >or=4 and a positive HIPA test were analyzed. Mean additional costs of a HIT case were 9008 euro. The main cost drivers were prolonged in-hospital stay (70.3%) and costs of alternative anticoagulants (19.7%). HIT was more costly in surgical patients compared with medical patients and in patients with thrombosis. Early start of alternative anticoagulation did not increase HIT costs despite the high medication costs indicating prevention of costly complications. An HIT cost calculator is provided, allowing online calculation of HIT costs based on local cost structures and different currencies.

[Oral anticoagulation after major hip or knee replacement surgery: a process-driven managerial pharmacoeconomic analysis in German hospitals]. / Orale Antikoagulation bei Hüft- und Kniegelenkersatzpatienten: Prozessanalyse in Akut- und Rehabilitationskliniken.

BACKGROUND: The thrombin inhibitor dabigatranetexilat is used for prophylaxis of venous thromboembolism after total hip or knee replacement surgery (THR/TKR). Patients can take it orally in hospitals. METHOD: In a managerial pharmacoeconomic analysis of six German acute-care hospitals and six German rehabilitation hospitals, the use of dabigatranetexilat was compared with the use of low-molecular-weight heparins. RESULTS: The analysis showed that the new drug led to an economic advantage for an acute-care hospital of 2.43 euro per patient per day. In a rehabilitation hospital, the use of dabigatranetexilat led to an economic advantage of 1.40 euro per patient per day. CONCLUSION: These results have direct implications for drug decisions in hospitals. To demonstrate that fact, the price difference between dabigatranetexilat and low-molecular-weight heparins was derived to lead exactly to their"economic neutrality" from the hospital's point of view.

The solute carrier family SLC10: more than a family of bile acid transporters regarding function and phylogenetic relationships.

The solute carrier family 10 (SLC10) comprises two sodium-dependent bile acid transporters, i.e. the Na(+)/taurocholate cotransporting polypeptide (NTCP; SLC10A1) and the apical sodium-dependent bile acid transporter (ASBT; SLC10A2). These carriers are essentially involved in the maintenance of the enterohepatic circulation of bile acids mediating the first step of active bile acid transport through the membrane barriers in the liver (NTCP) and intestine (ASBT). Recently, four new members of the SLC10 family were described and referred to as P3 (SLC10A3), P4 (SLC10A4), P5 (SLC10A5) and sodium-dependent organic anion transporter (SOAT; SLC10A6). Experimental data supporting carrier function of P3, P4, and P5 is currently not available. However, as demonstrated for SOAT, not all members of the SLC10 family are bile acid transporters. SOAT specifically transports steroid sulfates such as oestrone-3-sulfate and dehydroepiandrosterone sulfate in a sodium-dependent manner, and is considered to play an important role for the cellular delivery of these prohormones in testes, placenta, adrenal gland and probably other peripheral tissues. ASBT and SOAT are the most homologous members of the SLC10 family, with high sequence similarity ( approximately 70%) and almost identical gene structures. Phylogenetic analyses of the SLC10 family revealed that ASBT and SOAT genes emerged from a common ancestor gene. Structure-activity relationships of NTCP, ASBT and SOAT are discussed at the amino acid sequence level. Based on the high structural homology between ASBT and SOAT, pharmacological inhibitors of the ASBT, which are currently being tested in clinical trials for cholesterol-lowering therapy, should be evaluated for their cross-reactivity with SOAT.

Phylogeographical patterns in the American Pacific Northwest: lessons from the arionid slug Prophysaon coeruleum.

Some of the earliest studies of phylogenetic concordance involve native plants from the Pacific Northwest where many taxa showed clear genetic breaks between southern and northern populations. To test whether similar breaks also occur in invertebrate species with low dispersal capacities, genetic data from two mitochondrial genes are assembled for individuals of the arionid slug Prophysaon coeruleum throughout the species' range. Bayesian inference revealed three major clades and a total of eight subclades. It is argued that the demographic and genealogical past of P. coeruleum has resulted in a deep and shallow phylogeographical structure. The deep structure is at least 2.6-5.9 million years old and therefore clearly predates the Pleistocene period. Superimposed on this structure is a shallow structure that is most likely less than 2 million years old and probably the result of Pleistocene perturbations. Molecular analyses revealed that the three known colour traits in P. coeruleum do not represent monophyletic groups and that they do not match the patterns of genetic structure found. It is argued that the colour traits are perhaps a response to different levels of UV-radiation. The study adds to the increasing evidence that the phylogeographical structure of some taxa is more complex than previously thought. Moreover, it shows that genealogical concordance should not be deduced from phylogeographical patterns alone but should be based on an understanding of timing and causes of historical processes that lead to those patterns.

Separating historic events from recurrent processes in cryptic species: phylogeography of mud snails (Hydrobia spp.).

The present study combines methods that were designed to infer intraspecific relationships (e.g. nested-clade analysis (NCA), mismatch distributions and maximum likelihood gene flow analysis) to analyse historic events and recurrent processes in the cryptic mud snail species Hydrobia acuta and H. glyca. Specifically, we test the proposed allopatry of cryptic species and whether the peculiar range-subdivision of the putative subspecies H. a. acuta and H. a. neglecta is a result of long-distance dispersal or continuous range expansion. The NCA indicates a past fragmentation of the two H. acuta subspecies as well as past fragmentations within H. glyca. Gene-flow analyses show extensive gene flow in an E-W direction (towards the Atlantic) in the Mediterranean H. a. acuta, generally low gene flow in a W-E direction in the Atlantic H. a. neglecta and complex gene-flow pattern in a N-S but also in a S-N direction (against the Gulf Stream) in H. glyca. Based on these data and supportive ecological and oceanographical data, we hypothesize that the separation of the two H. acuta subspecies was not caused by long-distance dispersal but by a range shift and/or range expansion of the closely related competitor H. glyca as a result of an interglacial warming with a subsequent range shift in H. acuta. Moreover, our data do not show evidence for a long-term, stable sympatry of Hydrobia species, supporting the concept of allopatric relationships within cryptic radiations. NCA and gene-flow analyses indicate that the only sympatric population found in our study is the result of a recent dispersal event from the nearby Mediterranean. It is assumed that allopatric relationships in ephemeral Hydrobia populations constitute an evolutionary advantage relative to competition, recruitment and re-establishment of habitats. Mechanisms that could be of relevance for maintaining allopatry are discussed.

Reconciling genetic expectations from host specificity with historical population dynamics in an avian brood parasite, Horsfield's Bronze-Cuckoo Chalcites basalis of Australia.

Mitochondrial DNA (mtDNA) is being used increasingly to explore the evolution of host specificity in avian brood parasites. A stable coevolutionary equilibrium between multiple phylogenetically unrelated hosts and a brood parasitic species predicts that mtDNA diversity in the parasite should be relatively deep and phylogenetically structured. Also, the different intraspecific clades resulting from parasitism to multiple sympatric hosts should themselves occur sympatrically. However, mtDNA diversity in brood parasites is as susceptible to effects of historical population dynamics as in any species. We demonstrate the relevance of these dynamics to the use of mtDNA in understanding coevolution between an Australian brood-parasite, Horsfield's Bronze-Cuckoo Chalcites basalis and its hosts, Malurus fairy-wrens and Acanthiza thornbills. Previous ecological and behavioural analyses argue that Malurus- and Acanthiza-specific host races exist in C. basalis. Yet mtDNA diversity in C. basalis is low and phylogenetically unstructured (mean sequence divergence 0.15 +/- 0.07%, range 0.00%-0.31%) and tests of mtDNA neutrality and range expansion vs. population stability (Tajima's D, Fu & Li's F* and D*, Fu's F(S), mismatch analyses) all indicate that C. basalis has expanded its range very recently, probably within the last few tens of thousands of years following climatic amelioration after a peak of aridity in the late Pleistocene. The low mtDNA diversity and its lack of phylogenetic structure in C. basalis deny the existence of evolutionarily long-term stable host races in C. basalis but not the possibility of recently evolved ones. They highlight the need for renewed behavioural and ecological study of the relationship between C. basalis and its hosts. Our findings illustrate the need to understand the evolutionary context in which a brood parasite and its hosts have evolved if mtDNA data are to be used in testing hypotheses concerning the origin and maintenance of host specificity. They also add to the growing body of work illustrating the use of mismatch analyses and Fu's F(S) in detecting range expansions.

Oncomelania hupensis (Gastropoda: rissooidea) in eastern China: molecular phylogeny, population structure, and ecology.

The rissooidean snail genus Oncomelania is of medical interest as various taxa are hosts for the human blood fluke Schistosoma and the lung fluke Paragonimus; because of close co-evolved host-parasite-relationships, snail diversity may reflect parasite diversity. There is a considerable amount of confusion regarding the identity of smooth- and ribbed-shelled populations of Oncomelania hupensis in eastern China. We therefore studied the genetic variation, population structure, phylogenetic relationships and ecology of five smooth- and five ribbed-shelled populations in Hubei, Hunan, Anhui, Zhejiang, and Jiangsu provinces. Based on sequencing data of a fragment of the mitochondrial gene for cytochrome oxidase I from 80 individuals, we found little genetic variability within the ingroup-individuals studied here (average pi=0.01922). Moreover, within the ingroup, smooth-shelled individuals cluster together with ribbed-shelled individuals. We therefore consider all smooth- and ribbed-shelled populations of Oncomelania throughout the lower Yangtze River basin to belong to the subspecies O. hupensis hupensis. Our data indicate that ribbing in O. h. hupensis is associated with the annual floods of the Yangtze River. The greatest haplotype (d(H)) and nucleotide diversities (pi) are found in aggregates of ribbed-shelled snails along areas of the Yangtze River drainage subject to flooding. In areas not affected by flooding, the shells are smooth and genetic diversity decreases significantly.