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Oral versus intra-vaginal imidazole and triazole anti-fungal treatment of uncomplicated vulvovaginal candidiasis (thrush).

BACKGROUND: Anti-fungals are available for oral and intra-vaginal treatment of vulvovaginal candidiasis (thrush). OBJECTIVES: The primary objective of this review was to assess the relative effectiveness of oral versus intra-vaginal anti-fungals for the treatment of uncomplicated vulvovaginal candidiasis. The secondary objectives of the review were to assess the cost-effectiveness, safety and patient preference of oral versus intra-vaginal anti-fungals. SEARCH STRATEGY: The following sources were searched: The Cochrane Library (Issue 4, 1999), MEDLINE (January 1985 to May 2000), EMBASE (January 1980 to January 2000) and the Cochrane Collaboration Sexually Transmitted Disease Group Specialised Register of Controlled Trials. The reference lists of retrieved articles were reviewed manually. The manufacturers of anti-fungals available in the UK were contacted. SELECTION CRITERIA: ~Bullet~Randomised controlled trials published in any language. ~Bullet~Trials had to compare at least one oral anti-fungal with one intra-vaginal anti-fungal. ~Bullet~Women (aged 16 years or over) with uncomplicated vulvovaginal candidiasis. ~Bullet~The diagnosis of vulvovaginal candidiasis to be made mycologically (i.e. a positive culture and / or microscopy for yeast). ~Bullet~Trials were excluded if they solely involved subjects who were HIV positive, immunocompromised, pregnant, breastfeeding or diabetic. ~Bullet~The primary outcome measure was clinical cure. DATA COLLECTION AND ANALYSIS: Duplicate scrutiny was performed of the titles and abstracts of the electronic search results. Full article formats of all selected abstracts were retrieved and independently assessed by two reviewers. Independent duplicate abstraction was performed by four reviewers. Disagreements regarding trial inclusion or data abstraction were resolved by discussion between the reviewers. Odds ratios were pooled using the random effects model. Chi-squared tests with a p-value of less than 0.1 indicated heterogeneity in the results. MAIN RESULTS: Seventeen trials are included in the review, reporting 19 oral versus intra-vaginal anti-fungal comparisons. No statistically significant differences were shown between oral and intra-vaginal anti-fungal treatment for clinical cure at short term (OR 1.00 (95% CI, 0.72 to 1.40)) and long term (OR 1.03 (95% CI, 0.72 to 1.49)) follow-up. No statistically significant differences for mycological cure were observed between oral and intra-vaginal treatment at short term (OR 1.20(95% CI, 0.87 to 1.65)) or long term follow-up (OR 1.30 (95% CI, 0.99 to 1.71)). Two trials each reported one withdrawal from treatment due to an adverse reaction. Treatment preference data were poorly reported. REVIEWER'S CONCLUSIONS: No differences exist in terms of the relative effectiveness (measured as clinical and mycological cure) of anti-fungals administered by the oral and intra-vaginal routes for the treatment of uncomplicated vaginal candidiasis. No definitive conclusion can be made regarding the relative safety of oral and intra-vaginal anti-fungals for uncomplicated vaginal candidiasis. The oral route of administration is the preferred route for anti-fungals for the treatment of vulvovaginal candidiasis. The decision to prescribe or recommend the purchase of an anti-fungal for oral or intra-vaginal administration should take into consideration: safety, cost and treatment preference. Unless there is a previous history of adverse reaction to one route of administration or contraindications: if women are purchasing their own treatment, they should be given full information about the characteristics and costs of treatment to make their own decision. If health services are paying the treatment cost, decision-makers should consider whether the higher cost of oral anti-fungal administration is worth the gain in convenience, if this is the patient's preference.

Administration, Intravaginal↗

The membrane-bound intestinal enzymes of waxwings and thrushes: adaptive and functional implications of patterns of enzyme activity.

Cedar waxwings (Bombycilla cedrorum) feed predominantly on fruits that are rich in simple sugars and low in nitrogen, supplementing this diet with arthropod prey during the summer months as well as flowers and tree sap in springtime. In contrast, thrushes feed extensively on fatty, protein-rich invertebrate prey, supplemented with sugary and lipid-rich fruits. Simple sugars and fats are digested and/or absorbed by distinctly different physiological mechanisms, which suggests the possibility of contrasting digestive strategies in animals specialized to diets containing one of these two energy sources. In this study, we quantified enzymatic activity of three membrane-bound intestinal enzymes of cedar waxwings and five species of thrushes to explore this aspect of their digestive physiology. These enzymes catalyze the final steps in the digestion of carbohydrates (sucrase-isomaltase and maltase-glucoamylase) and protein (aminopeptidase-N). The two carbohydrases are homologous enzymes with overlapping functions; both enzymes catalyze the hydrolysis of maltase and isomaltase. The membrane-bound digestive enzyme systems that we described for cedar waxwings and thrushes can be explained by the particular nutrients contained within their respective natural diets. Consistent with previous work, cedar waxwings displayed intestinal sucrase activity, whereas thrushes did not. Correspondingly, cedar waxwings eat some foods containing sucrose, whereas thrushes do not. Sucrase-isomaltase conferred all maltase and isomaltase activity in cedar waxwings. In contrast, all maltase and isomaltase activity in thrushes was necessarily sucrase independent, which indicated the presence of maltase-glucoamylase. The absence of sucrase-independent maltase activity in cedar waxwings suggests that sucrase-isomaltase obviates the need for maltase-glucoamylase. Indeed, total maltase and isomaltase activities were much higher in cedar waxwings than in thrushes. Neither waxwings nor thrushes eat starchy foods; sucrase-isomaltase in waxwings and maltaseglucoamylase in thrushes probably function in digesting glycogen in animal foods. We suggest that digestive traits associated with specialization to monosaccharide-rich fruits (lack of a grinding gizzard) by frugivorous waxwings and thrushes may prevent utilization of starchy seeds. Total aminopeptidase-N activity in cedar waxwings was indistinguishable from the allometric pattern among thrush species, but the distribution of this enzyme along the intestines of waxwings and thrushes was distinctly different, which demonstrates that total enzyme activity can be insufficient as a descriptor of the functional activity of brush border enzymes. Aminopeptidase-N activity peaked in the anterior part of the intestines of thrushes and in the terminal portion of the intestines of waxwings, which suggests contrasting strategies for protein digestion from fatty versus sugary diets, respectively.

Animals↗

Thrush can be prevented in patients with acquired immunodeficiency syndrome and the acquired immunodeficiency syndrome-related complex. Randomized, double-blind, placebo-controlled study of 100-mg oral fluconazole daily.

Recurrent oropharyngeal candidiasis is common in patients with acquired immunodeficiency syndrome and the acquired immunodeficiency syndrome-related complex. It causes local pain and discomfort, loss of taste, and aversion to food and may lead to secondary complications. We examined, in a double-blind study, whether recurrent thrush could be prevented by prophylaxis. Twenty-five patients with one to four previous thrush episodes who had no thrush at the outset of the study were randomized to receive 100 mg of fluconazole or placebo daily for 12 weeks. If thrush occurred, prophylaxis was stopped and patients were treated conventionally, after which prophylaxis was resumed. After the randomized study, some patients were given continuous fluconazole (open phase). In the randomized study, thrush occurred in eight of 13 placebo-treated patients and none of 12 fluconazole-treated patients. Possible side effects were not different between the groups. Dermatophytosis and onychomycosis and cryptococcuria also improved in the fluconazole-treated patients, and fungal colonization was significantly decreased. One episode of thrush occurred in the open phase in an intermittently compliant patient (group total, 71.5 patient-months of fluconazole treatment); in contrast, the 25 patients also had had two episodes of Candida esophagitis, three of cryptococcosis, and 13 of dermatophytosis before entry. Subsequent to entry in the randomized trial, in 92.3 patient-months without fluconazole, there were 35 episodes of thrush, one of esophagitis, one of cryptococcemia, and one of dermatophytosis, and preexisting dermatophytosis and onychomycosis were unchanged or worsened. Individual patients observed with and without fluconazole treatment also showed its efficacy. In conclusion, thrush can be prevented in patients with acquired immunodeficiency syndrome and the acquired immunodeficiency syndrome-related complex with negligible toxic effects. Larger trials to confirm prevention of all mycoses with prophylaxis should be considered.

AIDS-Related Complex↗

Vaginal thrush and its management in pregnancy.

The frequency of vaginal thrush was determined in an unselected group of patients attending the antenatal clinic. Diagnosis was based on phase-contrast microscopy and culture. One hundred and two patients were initially included but only 98 completed this study. Thrush infection was detected in 25 (25%) patients. All 25 patients underwent treatment with one vaginal ovule containing 400 mg ketoconazole on each of three successive evenings. Thrush attack was eliminated in 23 (92%) cases. In view of the virtual absence of clinical symptoms, the recommendation to undertake general screening for thrush in pregnancy is discussed. The efficacy of treatment with ketoconazole ovules was studied and the results of treatment were reviewed after 4 and 8 weeks. Recurrence or re-infection has to be considered in pregnancy so that thrush treatment should sensibly be undertaken in the third trimester unless subjective symptoms indicate the need for earlier therapy.

Candidiasis, Vulvovaginal↗

Thrush and fever as measures of immunocompetence in HIV-1-infected men.

The occurrence of Pneumocystis carinii pneumonia (PCP) in human immunodeficiency virus type 1 (HIV-1)-infected individuals with high CD4+ counts indicates poor immunologic function. Thrush and persistent fever, easily recognized clinically, are potential measures of immunocompetence. This analysis establishes the complex interactions of CD4+ count, thrush, and persistent fever to predict the occurrence of PCP. Analyses used 20,632 person visits from 2,568 HIV-1-seropositive homosexual or bisexual men participating in the Multicenter AIDS Cohort Study (MACS). Comprehensive examinations were conducted semiannually, while occurrences of PCP were assessed continuously. The occurrence of thrush and fever increase in frequency as CD4+ levels decrease. The relative hazard of PCP in the presence of thrush compared with the absence of thrush rises (p < 0.05) from 1 for the lowest CD4+ category to approximately 5 in the highest categories. The relative hazard of PCP in the presence of fever compared with the absence of fever is above one (p < 0.05) in all CD4+ categories. No cases of PCP occurred in individuals on PCP prophylaxis with CD4+ counts > 200/mm3. These results suggest that HIV-1-related symptoms provide a measure of failing immune function that is not reflected by enumeration of CD4+ lymphocytes alone and support the United States Public Health Service recommendation that symptomatic individuals with CD4+ counts > 200/mm3 should be considered for PCP prophylaxis.

Bisexuality↗

Community pharmacists' views and beliefs about the treatment of symptoms suggestive of vaginal thrush in community pharmacies.

OBJECTIVE: To investigate the views and beliefs of community pharmacists about the benefits and disadvantages to the customer, pharmacy and pharmacist of treating women with symptoms suggestive of vaginal thrush. DESIGN: Semi-structured interviews. SETTING: Community pharmacists from within Grampian Primary Care NHS Trust. OUTCOME MEASURES: Pharmacists' views and beliefs analysed using content analysis. RESULTS: Of the 26 pharmacists contacted, 19 (73%) pharmacists from 16 pharmacies completed interviews. The pharmacists were generally positive towards the treatment of women with vaginal symptoms and perceived few disadvantages. Immediate access to treatment and rapid symptom relief were perceived to be the greatest advantages to the customer. The main problems were customer embarrassment, cost and the risk of masking a serious condition. Customer embarrassment was perceived to be influenced by lack of privacy and the gender of the member of staff involved in the consultation. Five pharmacists perceived vaginal thrush to be an infection that could be spread by sexual transmission. DISCUSSION: There is a need to make pharmacists aware of the current evidence regarding the treatment of vaginal thrush, particularly the sexual partners of women with acute, uncomplicated thrush do not require treatment with an antifungal. The main difficulties that community pharmacists reported with the treatment of this condition were obtaining an accurate history and this was influenced by customer embarrassment. The gender of pharmacy staff and lack of private consultation facilities were suggested as factors that are associated with customer embarrassment and hence, the ability to obtain an accurate history.

Adult↗

Identification of Candida albicans genes induced during thrush offers insight into pathogenesis.

Candida albicans causes a wide spectrum of diseases, ranging from mucocutaneous infections like oral thrush to disseminated candidiasis. Screening for C. albicans genes expressed within infected hosts might advance understanding of candidal pathogenesis, but is impractical using existing techniques. In this study, we used an antibody-based strategy to identify C. albicans genes expressed during thrush. We adsorbed sera from HIV-infected patients with thrush against candidal cells grown in vitro and screened a C. albicans genomic expression library. We identified 10 genes encoding immunogenic antigens and used reverse transcription-polymerase chain reaction to verify that they were induced within thrush pseudomembranes recovered from a patient. The in vivo induced genes are involved in diverse functions, including regulation of yeast-hyphal morphogenesis, adhesion to host cells, nutrient uptake, phospholipid biosynthesis and amino acid catabolism. Four genes encode known virulence determinants (HWP1, CST20, CPP1 and RBF1). Another gene, LPD1, for which a role in candidal pathogenesis is unknown, encodes a protein homologous to a bacterial virulence determinant. Most importantly, disruption of CaNOT5, a newly identified gene, conferred defects in morphogenesis, decreased adherence to human buccal epithelial cells and attenuated mortality during murine disseminated candidiasis, proving that our strategy can identify genes encoding novel virulence determinants.

AIDS-Related Opportunistic Infections↗

Vaginal thrush: perceptions and experiences of women of south Asian descent.

It is estimated that 75% of all women will, at some time in their lives, experience at least one episode of vaginal thrush. This paper reports the perceptions and experiences of women of South Asian descent living in England, who were suffering or had suffered from thrush. The paper draws upon data collected during 20 semi-structured interviews. The women reported that thrush sometimes had a considerable impact on their lives, making some of them feel 'dirty', embarrassed, depressed and stigmatized. Some women delayed seeking professional help even if they had access to a female General Practitioner. Access to professional care was sometimes hampered by language barriers, but more often by structural factors of gender and social class. Although almost all the women came originally from Gujarat (or had parents who were born in Gujarat), they reported a wide range of experiences. Since vaginal thrush causes much distress and since it is often preventable, the findings presented here have implications for clinical practice. The paper concludes with suggestions for future developments.

Adult↗

A comparison between fluconazole tablets and clotrimazole troches for the treatment of thrush in HIV infection.

Fluconazole, a newly available triazole, has been evaluated extensively as a treatment for thrush. It has been effective in the treatment of this condition in patients with HIV infection. Clotrimazole troches have been a common treatment for thrush in patients with HIV infection for several years. This study compared the efficacy and safety of fluconazole 100 mg tablets once per day versus clotrimazole 10 mg troches five times per day in the treatment of thrush in patients with HIV infection. Patients were evaluated at baseline, day 7, 14, 28, and 42. The following parameters were evaluated: clinical cure, colonization at the end of treatment, relapse at day 28, and relapse at day 42. Side effects including liver enzyme values were also monitored. Clinical cure was superior with fluconazole tablets than with clotrimazole troches. Also, rates of colonization at the end of therapy and relapse at days 28 and 42 were less with fluconazole tablets than with clotrimazole troches. However, these differences were not statistically significant. Patient compliance with fluconazole was superior to that of clotrimazole. This difference was statistically significant. Both fluconazole tablets and clotrimazole troches are effective in treating thrush in patients with HIV infection. The avoidance of multiple-per-day dosing would appear to favor fluconazole.

AIDS-Related Opportunistic Infections↗

Topical treatment for vaginal candidiasis in pregnancy.

BACKGROUND: Vaginal candidiasis (moniliasis or thrush) is a common and frequently distressing infection for many women. It is even more common in pregnancy. OBJECTIVES: The objective of this review was to assess the effects of different methods of treating vaginal candidiasis in pregnancy. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register. In addition, the Cochrane Controlled Trials Register (CENTRAL/CCTR) was searched. Date of last search: April 1999. SELECTION CRITERIA: Randomised trials of any treatment for vaginal candidiasis in pregnancy. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and extracted data. MAIN RESULTS: Twelve trials were included. Based on five trials, imidazole drugs were more effective than nystatin when treating vaginal candidiasis in pregnancy (odds ratio 0.21, 95% confidence interval 0.16 to 0.29). Nystatin,in turn was more effective than hydrargaphen in one trial.A trial of clotrimazole was more effective than placebo (odds ratio 0.14, 95% confidence interval 0.06 to 0.31). Single dose treatment was less effective than three or four days treatment when assessed by culture and by symptoms in three different trials and treatment lasting for four days was less effective than treatment for seven days (odds ratio 10.6, 95% confidence interval 4.01 to 28.05). Based on two trials, treatment for seven days was no more or less effective than treatment for 14 days (odds ratio 0.41, 95% confidence interval 0.16 to 1.05). REVIEWER'S CONCLUSIONS: Topical imidazole appears to be more effective than nystatin for treating symptomatic vaginal candidiasis in pregnancy. Treatments for seven days may be necessary.

Administration, Topical↗

Using Shannon entropy on measuring the individual variability in the Rufous-bellied thrush Turdus rufiventris vocal communication.

We applied the information theory concepts to notes repertoire characteristics combined with temporal parameters of the Rufous-bellied thrush Turdus rufiventris song, using this particular case to test a new method of analysing quantitatively complex animal communication systems. Like most Turdus thrushes, Rufous-bellied thrushes are remarkable for their long, varied and melodious songs. For the analysis of the species repertoire, we used recordings of 44 individuals from 24 localities covering its full geographical range. We measured the repertoire size, note duration and rhythm (frequency of note utterance), and combined these parameters with the Shannon entropy values calculated for each individual. Although individuals maintain species-specific recognition capacity, we find a large variation between their song parameters and show that the information theory can be useful to analyse large and varied animal vocal repertoires. We are introducing two new parameters, temporal average entropy (E(t)) and utterance frequency average entropy (E(f)), for measuring such communication systems.

Animals↗

Effects of food shortage and oversupply on energy utilization, histology, and function of the gut in nestling song thrushes (Turdus philomelos).

We measured food intake, digestive efficiency, body mass increments, resting metabolic rate (RMR), carcass fat content, size and histological structure of the gut, and the rate of intestinal brush border uptake of l-proline in song thrush (Turdus philomelos) nestlings subjected to food shortage or food surplus under laboratory conditions. We assigned nestlings between 3 and 7 d of age to one of the following treatments: (1) food restriction, which resulted in a slowed growth at the rate found in undernourished, wild nestlings; (2) overfeeding, which totally suppressed begging; and (3) intermediate feeding. Threefold differences in energy consumption caused fivefold differences in body mass increments of the nestlings. Despite this, body mass-corrected RMR and intestinal mass were not affected by the feeding regime. The energy content of fecal output was highest in food-restricted birds, while their carcass fat content was lowest among treatment groups. Intestinal uptake rates of l-proline were low in the overfed and intermediate-fed young but significantly increased in the food-restricted birds, who attempted to maximize their rates of growth and development within the restrictive limits set by feeding regime. We noted a marked decrease of intestinal villi height in overfed birds as compared to intermediate-fed and food-restricted nestlings. We conclude that song thrush nestlings are characterized by a limited plasticity of their developmental program, which prohibits overfed nestlings from significantly up-regulating their gut function to accommodate increased food intake. This suggests that they already grew at a rate close to their physiological maximum. We suggest two interpretations: (1) under natural conditions, song thrush nestlings do not face frequent, unpredictable fluctuations in food abundance that could select for developmental plasticity, or (2) strong selection for uniform adult phenotypes prevents flexible developmental trajectories, which would result in a diversity of adult phenotypes.

Adipose Tissue↗

Thrush and fever as markers of immune competence in the era of highly active antiretroviral therapy.

The presence of clinical manifestations of HIV-1 infection is one measure of immune function failure. We examined the occurrence of clinical manifestations of HIV-1 infection, in particular fever and oral thrush, before and after the initiation of highly active antiretroviral therapy (HAART). Using data collected from 645 participants in the Multicenter AIDS Cohort Study (MACS) who used HAART, 7517 person-visits from January 1992 through March 2000 were stratified by time relative to HAART initiation (> or =1 year preinitiation, <1 year preinitiation, >1 year postinitiation, and > or =1 year postinitiation) and CD4+ T cell count (< or =100, 101-200, 201-350, and >350 cells/microl). Multivariate logistic regression was used to assess the relationship between HAART, CD4+ T cell count, and each self-reported symptom (oral hairy leukoplakia, diarrhea, fever, and oral thrush). After initiation of HAART, clinical manifestations of HIV-1 infection continued to occur and, similar to patterns seen before HAART, were more likely at lower CD4+ T cell counts than at higher (p < 0.001). Except for diarrhea, symptoms did not occur more frequently after HAART. Rather, beyond 1 year after initiation of HAART, there was less oral thrush even at the same CD4+ T cell count. These results provide evidence that increases in CD4+ T cell count due to HAART represent a reconstitution of immune function.

AIDS-Related Opportunistic Infections↗

Randomized comparison of two nystatin oral gels with miconazole oral gel for treatment of oral thrush in infants. Antimycotics Study Group.

Recently, two commercial oral nystatin gels have been marketed in Germany (Candio-Hermal, Hermal; Lederlind, Lederle). In a prospective open randomized multicentre study involving 12 paediatricians in private practice, Candio-Hermal and Lederlind were compared with miconazole oral gel (Daktar, Janssen) in 95 infants with oral thrush (candidosis). Oral and rectal swabs were taken on days 0 and 14. Treatment duration varied according to the amount of drug contained in one tube (Candio-Hermal 10 days; Lederlind 14 days; Daktar 8 days). On day 14, clinical cure was observed in 23 of 27 infants treated with Daktar (85.1%), in 15 of 35 infants treated with Candio-Hermal (42.8%; p < 0.0007); and in 16 of 33 infants treated with Lederlind (48.5%; p < 0.004). Clinical relapses were observed in 15 patients (Candio-Hermal: n = 9; Lederlind: n = 6). The overall oral mycologic cure rate was significantly higher with Daktar (29.6%) and Candio-Hermal (20.0%) than with Lederlind (3.0%; p < 0.005 and < 0.03, respectively). It can be concluded that Daktar oral gel is significantly more effective than Candio-Hermal and Lederlind in curing oral thrush in infants.

Candidiasis, Oral↗

A simple clinical staging system that predicts progression to AIDS using CD4 count, oral thrush, and night sweats.

OBJECTIVE: To develop a simple clinical staging system based on CD4 count and clinical variables that predicts progression to AIDS in HIV-infected non-AIDS patients. DESIGN: Retrospective cohort study. SETTING: A primary care outpatient clinic for HIV-infected patients at a VA Medical Center. PATIENTS: One hundred seventy-six HIV-infected non-AIDS patients seen at the Houston VA Special Medicine Clinic between January 1986 and December 1990 and followed for a mean of 22 months. Fifty-four patients (31%) progressed to AIDS during follow-up. MEASUREMENTS: The medical records were reviewed, and data corresponding to the initial (baseline) clinic visit and subsequent six-month visits were extracted. MAIN RESULTS: "Predictive" baseline variables (i.e., those associated with progression to AIDS) were first identified and then examined in Cox proportional hazards modeling. In the final model, CD4 category, oral thrush, and night sweats made significant independent contributions. A three-stage prognostic system was constructed by assigning points to the three variables: CD4 > 500 cells/mm3 = 0; 500 > or = CD4 > or = 200 = 1; CD4 < 200 = 2; presence of oral thrush = 1; presence of night sweats = 1. Stages were assigned as follows: stage I = 0 points, stage II = 1-2 points, and stage III = 3-4 points. The proportions of patients who progressed to AIDS were: stage I, 6/39 (15%); stage II, 31/106 (29%); and stage III, 17/31 (55%). CONCLUSIONS: These results demonstrate that simple, clinically sensible prognostic staging systems that predict progression to AIDS can be constructed using CD4 count and clinical variables.

AIDS-Related Opportunistic Infections↗

Efficacy of oral amphotericin B in AIDS patients with thrush clinically resistant to fluconazole.

Reports of thrush clinically refractory to azoles in AIDS patients are increasing with the more widespread use of these agents. We studied our own oral preparation of amphotericin B in the treatment of two AIDS patients who developed oral thrush due to Candida glabrata after prolonged fluconazole use. Improvement occurred in both in less than 1 week, with eventual clearing and absence of side effects. Oral amphotericin B may have advantages over alternatives for this increasing problem.

Acquired Immunodeficiency Syndrome↗

Not as the crow flies: a historical explanation for circuitous migration in Swainson's thrush (Catharus ustulatus).

Many migratory songbirds follow circuitous migratory routes instead of taking the shortest path between overwintering and breeding areas. Here, we study the migration patterns in Swainson's thrush (Catharus ustulatus), a neartic-neotropical migrant songbird, using molecular genetic approaches. This species is presently separated into genetically distinct coastal and continental populations that diverged during the Late Pleistocene (as indicated by molecular dating), yet appear to have retained ancestral patterns of migration. Low nucleotide diversity, a star-like haplotype phylogeny and unimodal mismatch distributions all support the hypothesis that both the coastal and the continental populations have undergone recent demographic expansions. Nearctic-neotropical banding and genetic data show nearly complete segregation of migratory routes and of overwintering locations: coastal populations migrate along the Pacific Coast to overwintering sites in Central America and Mexico, whereas continental populations migrate along an eastern route to overwintering sites in Panama and South America. Nearctic-neotropical banding data also show that continental birds north, northwest and east of this migratory divide fly thousands of miles east before turning south. We conclude that circuitous migration in the Swainson's thrush is an artefact of a Late Pleistocene range expansion.

Animal Migration↗