La Enfermedad Research Articles

First indigenous transmission of Japanese Encephalitis in urban areas of National Capital Territory of Delhi, India

Until 2010, no Japanese encephalitis (JE) had been reported from Delhi. Upon report of four confirmed cases of JE in September 2011, detailed investigations were carried out to determine whether the cases were imported or indigenous. Entomological surveys were carried out and all mosquito pools were tested for the detection of JE virus by ELISA method using specific monoclonal antibody. Human blood samples from contacts of the patients were tested by IgM-captured ELISA method. Pig's blood samples were also tested for the detection of JE virus. Culex tritaeniorhynchus, Culex vishnui and Culex pseudovishnui mosquitoes were found. In contrast to rural areas, their breeding habitats were different in the city. 19 pools were tested. JE virus was detected in two pools of Cx.tritaeniorhynchus females reared from field-collected larvae, indicating vertical transmission. One pool of Cx.vishnui was also positive. This is the first report for the detection of JE virus in mosquitoes from Delhi. JE IgM antibodies in five contacts/residents indicate recent infection. JE virus was also detected in pigs. Present analysis shows that of four reported JE cases, three were confirmed indigenous, indicating that the virus is multiplying in the city. Mapping of infected JE vector mosquitoes in the cities is required for preventive measures to contain further spread of the disease.

Imported malaria: a possible threat to the elimination of malaria from Sri Lanka?

To discuss epidemiological aspects of imported malaria and the potential impact of imported malaria cases reported in Sri Lanka 2008-2011 in terms of a possible resurgence of the disease. The national malaria database was used to assess details regarding country where the infection was possibly acquired, species of Plasmodium, number of days lapsed between disembarkation in Sri Lanka and diagnosis, compliance with national treatment guidelines including percentage of patients followed up as per the national guidelines. After the strengthening of malaria surveillance, during the 4-year period, 152 imported malaria cases were recorded: an increase of 176% in the number of cases. Most of the imported malaria infections were acquired by Sri Lankan Nationals mainly from South Asia, especially India. Plasmodium vivax accounted for 64% of the infections. Approximately 50% of the cases were diagnosed in the Western Province. The average period from disembarkation in Sri Lanka to malaria diagnosis was 3.6days. Patients were managed and treated according to the national guidelines. 82% of the patients were followed up for 28days to ensure parasite clearance. There is a possible increasing risk of re-introduction of malaria to the country from imported cases. Enhanced surveillance activities and the increase in international travel have contributed to an increase in recorded case numbers. There is a need to further strengthen surveillance, especially for monitoring and timely addressing of imported malaria, if the country is to prevent the re-establishment of transmission within. The importance of having an efficient response mechanism to deal with imported malaria is also highlighted.

Low-molecular-weight or Unfractionated Heparin in Venous Thromboembolism: The Influence of Renal Function

BackgroundIn patients with acute venous thromboembolism and renal insufficiency, initial therapy with unfractionated heparin may have some advantages over low-molecular-weight heparin. MethodsWe used the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) Registry data to evaluate the 15-day outcome in 38,531 recruited patients. We used propensity score matching to compare patients treated with unfractionated heparin with those treated with low-molecular-weight heparin in 3 groups stratified by creatinine clearance levels at baseline: >60 mL/min, 30 to 60 mL/min, or <30 mL/min. ResultsPatients initially receiving unfractionated heparin therapy (n = 2167) more likely had underlying diseases than those receiving low-molecular-weight heparin (n = 34,665). Propensity score-matched groups of patients with creatinine clearance levels >60 mL/min (n = 1598 matched pairs), 30 to 60 mL/min (n = 277 matched pairs), and <30 mL/min (n = 210 matched pairs) showed an increased 15-day mortality for unfractionated heparin compared with low-molecular-weight heparin (4.5% vs 2.4% [P = .001], 5.4% vs 5.8% [P = not significant], and 15% vs 8.1% [P = .02], respectively), an increased rate of fatal pulmonary embolism (2.8% vs 1.2% [P = .001], 3.2% vs 2.5% [P = not significant], and 5.7% vs 2.4% [P = .02], respectively), and a similar rate of fatal bleeding (0.3% vs 0.3%, 0.7% vs 0.7%, and 0.5% vs 0.0%, respectively). Multivariate analysis confirmed that patients treated with unfractionated heparin were at increased risk for all-cause death (odds ratio, 1.8; 95% confidence interval, 1.3-2.4) and fatal pulmonary embolism (odds ratio, 2.3; 95% confidence interval, 1.5-3.6). ConclusionsIn comparison with low-molecular-weight heparin, initial therapy with unfractionated heparin was associated with a higher mortality and higher rate of fatal pulmonary embolism in patients with creatinine clearance levels >60 mL/min or <30 mL/min, but not in those with levels between 30 and 60 mL/min.

A LiTat 1.5 variant surface glycoprotein‐derived peptide with diagnostic potential for Trypanosoma brucei gambiense

To evaluate the accuracy of a peptide, corresponding to the variant surface glycoprotein (VSG) LiTat 1.5 amino acid (AA) sequence 268-281 and identified through alignment of monoclonal antibody selected mimotopes, for diagnosis of Trypanosoma brucei gambiense sleeping sickness. A synthetic biotinylated peptide (peptide 1.5/268-281), native VSG LiTat 1.3 and VSG LiTat 1.5 were tested in an indirect ELISA with 102 sera from patients with HAT and 102 endemic HAT-negative controls. The area under the curve (AUC) of peptide 1.5/268-281 was 0.954 (95% confidence interval 0.918-0.980), indicating diagnostic potential. The areas under the curve of VSG LiTat 1.3 and LiTat 1.5 were 1.000 (0.982-1.000) and 0.997 (0.973-1.000), respectively, and significantly higher than the AUC of peptide 1.5/268-281. On a model of VSG LiTat 1.5, peptide 1.5/268-281 was mapped near the top of the VSG. A biotinylated peptide corresponding to AA 268-281 of VSG LiTat 1.5 may replace the native VSG in serodiagnostic tests, but the diagnostic accuracy is lower than for the full-length native VSG LiTat 1.3 and VSG LiTat 1.5.

A Clinical Prognostic Model for the Identification of Low-Risk Patients With Acute Symptomatic Pulmonary Embolism and Active Cancer

Physicians need a specific risk-stratification tool to facilitate safe and cost-effective approaches to the management of patients with cancer and acute pulmonary embolism (PE). The objective of this study was to develop a simple risk score for predicting 30-day mortality in patients with PE and cancer by using measures readily obtained at the time of PE diagnosis. Investigators randomly allocated 1,556 consecutive patients with cancer and acute PE from the international multicenter Registro Informatizado de la Enfermedad TromboEmbólica to derivation (67%) and internal validation (33%) samples. The external validation cohort for this study consisted of 261 patients with cancer and acute PE. Investigators compared 30-day all-cause mortality and nonfatal adverse medical outcomes across the derivation and two validation samples. In the derivation sample, multivariable analyses produced the risk score, which contained six variables: age > 80 years, heart rate ≥ 110/min, systolic BP < 100 mm Hg, body weight < 60 kg, recent immobility, and presence of metastases. In the internal validation cohort (n = 508), the 22.2% of patients (113 of 508) classified as low risk by the prognostic model had a 30-day mortality of 4.4% (95% CI, 0.6%-8.2%) compared with 29.9% (95% CI, 25.4%-34.4%) in the high-risk group. In the external validation cohort, the 18% of patients (47 of 261) classified as low risk by the prognostic model had a 30-day mortality of 0%, compared with 19.6% (95% CI, 14.3%-25.0%) in the high-risk group. The developed clinical prediction rule accurately identifies low-risk patients with cancer and acute PE.

The place of the unknown in the Medical Humanities

In the birth and development of the Medical Humanities, literature has played a crucial role, both as an educational resource and as an analytical device. This article proposes an appraisal of this approach by focussing on a model literary situation. Taking the move from Alberto Barrera Tyszka's novel La enfermedad [The illness], the authors identify and explore some of the “places of ignorance” that can emerge in the doctor–patient relationship, as potentially in any form of intersubjective encounter. The analysis aims at highlighting the constructive potential of such spaces of not knowing as a positive element to deal with, rather than a mere limitation of our power of intervention.

Thirty-day mortality rate in women with cancer and venous thromboembolism. Findings from the Registro Informatizado de la Enfermedad Trombo Embólica Registry

Cancer patients with venous thromboembolism (VTE) are at increased risk of mortality. Estimating the risks for specific causes of death may help to weigh the risks and benefits of different therapeutic strategies in an individual patient. In the Registro Informatizado de la Enfermedad Trombo Embólica Registry of 15 520 consecutive patients with VTE, cancer was present in 20% and was associated with a two-fold increase in the risk of fatal pulmonary embolism. In a subsequent study including 2474 women with cancer, 329 (13%) died during the first month. The incidence of fatal pulmonary embolism (n = 71) exceeded that of fatal bleeding (n = 22), except in women with cancer of the bladder or vulva. Then, we compared the mortality rate according to initial presentation in 3978 women with cancer and VTE, of whom 438 (11%) died during the first month. The risk of fatal bleeding was twice as high as the risk of fatal pulmonary embolism (12 vs. 5 deaths) in those with deep-vein thrombosis alone. The higher risk of dying from bleeding than from pulmonary embolism in some women with cancer and VTE suggests that a less aggressive anticoagulant strategy might reduce fatal bleeding more than it would increase fatal pulmonary embolism during this period.

Screening of patients with tuberculosis for diabetes mellitus in China

There is a high burden of both diabetes (DM) and tuberculosis (TB) in China, and this study aimed to assess feasibility and results of screening patients with TB for DM within the routine healthcare setting of six health facilities. Agreement on how to screen, monitor and record was reached in May 2011 at a stakeholders' meeting, and training was carried out for staff in the six facilities in July 2011. Implementation started in September 2011, and we report on 7 months of activities up to 31 March 2012. There were 8886 registered patients with TB. They were first asked whether they had DM. If the answer was no, they were screened with a random blood glucose (RBG) followed by fasting blood glucose (FBG) in those with RBG ≥ 6.1 mm (one facility) or with an initial FBG (five facilities). Those with FBG ≥ 7.0 mm were referred to DM clinics for diagnostic confirmation with a second FBG. Altogether, 1090 (12.4%) patients with DM were identified, of whom 863 (9.7%) had a known diagnosis of DM. Of 8023 patients who needed screening for DM, 7947 (99%) were screened. This resulted in a new diagnosis of DM in 227 patients (2.9% of screened patients), and of these, 226 were enrolled to DM care. In addition, 575 (7.8%) persons had impaired fasting glucose (FBG 6.1 to <7.0 mm). Prevalence of DM was significantly higher in patients in health facilities serving urban populations (14.0%) than rural populations (10.6%) and higher in hospital patients (13.5%) than those attending TB clinics (8.5%). This pilot project shows that it is feasible to screen patients with TB for DM in the routine setting, resulting in a high yield of patients with known and newly diagnosed disease. Free blood tests for glucose measurement and integration of TB and DM services may improve the diagnosis and management of dually affected patients.

Thrombolytic therapy and outcome of patients with an acute symptomatic pulmonary embolism

While the primary therapy for most patients with a pulmonary embolism (PE) consists of anticoagulation, the efficacy of thrombolysis relative to standard therapy remains unclear. In this retrospective cohort study of 15,944 patients with an objectively confirmed symptomatic acute PE, identified from the multicenter, international, prospective, Registro Informatizado de la Enfermedad TromboEmbólica (RIETE registry), we aimed to assess the association between thrombolytic therapy and all-cause mortality during the first 3 months after the diagnosis of a PE. After creating two subgroups, stratified by systolic blood pressure (SBP) (< 100 mm Hg vs. other), we used propensity score-matching for a comparison of patients who received thrombolysis to those who did not in each subgroup. Patients who received thrombolysis were younger, had fewer comorbid diseases and more signs of clinical severity compared with those who did not receive it. In the subgroup with systolic hypotension, analysis of propensity score-matched pairs (n = 94 pairs) showed a non-statistically significant but clinically relevant lower risk of death for thrombolysis compared with no thrombolysis (odds ratio [OR] 0.72; 95% confidence interval [CI], 0.36-1.46; P = 0.37). In the normotensive subgroup, analysis of propensity score-matched pairs (n = 217 pairs) showed a statistically significant and clinically meaningful increased risk of death for thrombolysis compared with no thrombolysis (OR 2.32; 95% CI, 1.15-4.68; P = 0.018). When we imputed data for missing values for echocardiography and troponin tests in the group of normotensive patients, we no longer detected the increased risk of death associated with thrombolytic therapy. In normotensive patients with acute symptomatic PE, thrombolytic therapy is associated with a higher risk of death than no thrombolytic therapy. In hemodynamically unstable patients, thrombolytic therapy is possibly associated with a lower risk of death than no thrombolytic therapy. However, study design limitations do not imply a causal relationship between thrombolytics and outcome.

Treatment of demodicosis in dogs: 2011 clinical practice guidelines

These guidelines were written by an international group of specialists with the aim to provide veterinarians with current recommendations for the diagnosis and treatment of canine demodicosis. Published studies of the various treatment options were reviewed and summarized. Where evidence in form of published studies was not available, expert consensus formed the base of the recommendations. Demodicosis can usually be diagnosed by deep skin scrapings or trichograms; in rare cases a skin biopsy may be needed for diagnosis. Immune suppression due to endoparasitism or malnutrition in young dogs and endocrine diseases, neoplasia and chemotherapy in older dogs are considered predisposing factors and should be diagnosed and treated to optimize the therapeutic outcome. Dogs with disease severity requiring parasiticidal therapy should not be bred. Secondary bacterial skin infections frequently complicate the disease and require topical and/or systemic antimicrobial therapy. There is good evidence for the efficacy of weekly amitraz rinses and daily oral macrocyclic lactones such as milbemycin oxime, ivermectin and moxidectin for the treatment of canine demodicosis. Weekly application of topical moxidectin can be useful in dogs with milder forms of the disease. There is some evidence for the efficacy of weekly or twice weekly subcutaneous or oral doramectin. Systemic macrocyclic lactones may cause neurological adverse effects in sensitive dogs, thus a gradual increase to the final therapeutic dose may be prudent (particularly in herding breeds). Treatment should be monitored with monthly skin scrapings and extended beyond clinical and microscopic cure to minimize recurrences.

Clusters of leprosy transmission and of late diagnosis in a highly endemic area in Brazil: focus on different spatial analysis approaches

The Brazilian National Hansen's Disease Control Program recently identified clusters with high disease transmission. Herein, we present different spatial analytical approaches to define highly vulnerable areas in one of these clusters. The study area included 373 municipalities in the four Brazilian states Maranhão, Pará, Tocantins and Piauí. Spatial analysis was based on municipalities as the observation unit, considering the following disease indicators: (i) rate of new cases/100,000 population, (ii) rate of cases <15 years/100,000 population, (iii) new cases with grade-2 disability/100,000 population and (iv) proportion of new cases with grade-2 disabilities. We performed descriptive spatial analysis, local empirical Bayesian analysis and spatial scan statistic. A total of 254 (68.0%) municipalities were classified as hyperendemic (mean annual detection rates >40 cases/100,000 inhabitants). There was a concentration of municipalities with higher detection rates in Pará and in the center of Maranhão. Spatial scan statistic identified 23 likely clusters of new leprosy case detection rates, most of them localized in these two states. These clusters included only 32% of the total population, but 55.4% of new leprosy cases. We also identified 16 significant clusters for the detection rate <15 years and 11 likely clusters of new cases with grade-2. Several clusters of new cases with grade-2/population overlap with those of new cases detection and detection of children <15 years of age. The proportion of new cases with grade-2 did not reveal any significant clusters. Several municipality clusters for high leprosy transmission and late diagnosis were identified in an endemic area using different statistical approaches. Spatial scan statistic is adequate to validate and confirm high-risk leprosy areas for transmission and late diagnosis, identified using descriptive spatial analysis and using local empirical Bayesian method. National and State leprosy control programs urgently need to intensify control actions in these highly vulnerable municipalities.

Clinical characteristics of italian patients with venous thromboembolism enrolled in the RIETE Registry

Introduction: The clinical characteristics, treatment strategies and outcome of patients with venous thromboembolism (VTE) may vary from country to country. Materials and methods: The RIETE (Registro Informatizado su la Enfermedad TromboEmbolica) is an ongoing, prospective registry of consecutive patients with acute, objectively confirmed, symptomatic VTE. Our aim was to assess the influence of surgery and immobility for non-surgical reasons on 3-month outcomes of all Italian patients registered in the RIETE. Results: Through July 2008, 21,397 patients with acute VTE were registered in the RIETE. Of these, 896 (4.2%) were Italian, and 360 (40%) presented with pulmonary embolism (PE). Overall, 137 (15%) developed VTE after surgery; 156 (17%) developed VTE after &gt;4 days of immobility, and 603 (67%) developed VTE in the absence of surgery or immobility. Most patients (83%) received initial therapy with low-molecular-weight heparin; 15% received unfractionated heparin. For long-term therapy, 63% of patients received vitamin K antagonists. The incidence of fatal PE during the first 3 months of therapy was 1.5% for patients with postoperative VTE, 7.7% for who developed VTE after immobility, and 1.2% for the remaining patients. The incidence of fatal bleeding among these patients was 1.5%, 1.9% and 0.3%, respectively. Of the 137 patients with postoperative VTE, 61% had received VTE prophylaxis. Of the 156 patients with recent immobility, 24% had received VTE prophylaxis. Conclusions: VTE arising after a period of immobility was associated with the highest rates of fatal PE and fatal bleeding during the first 3 months of therapy. The use of thromboprophylaxis in this population should be improved.

Effects of age on the risk of dying from pulmonary embolism or bleeding during treatment of deep vein thrombosis

The risk of patients dying of pulmonary embolism (PE) or bleeding during the treatment of deep vein thrombosis (DVT), and whether these risks are influenced by patient age, has not been thoroughly studied. We used data from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) to assess the risk of fatal PE and fatal bleeding in 16,199 patients with lower limb DVT (without symptomatic PE at the time of inclusion) during the 3 months after diagnosis, with patients categorized according to age. During the 3 months of anticoagulant treatment, there were 31 fatal PEs (0.19%) and 83 fatal hemorrhages (0.51%). During the first 7 days of therapy, the frequency of fatal PEs was similar to that of fatal bleeding (12 vs 14 deaths, respectively; odds ratio [OR], 0.86; 95% confidence interval [CI], 0.39-1.87). However, from days 8 to 90, the frequency of fatal bleeding was greater than that of fatal PE (69 vs 19 deaths; OR, 3.64; 95% CI, 2.22-6.20). The higher frequency of fatal bleeding compared with fatal PE from days 8 to 90 appeared to be confined to patients who were aged ≥ 60 years. Multivariate analysis showed that patient age was independently associated with an increased risk of death from bleeding during the first 3 months: every 10 years the OR increased by 1.37 (95% CI, 1.12-1.67). During the first week of treatment, the risk of fatal bleeding and fatal PE were similar. Then, particularly in patients who were aged ≥ 60 years, the risk of dying from bleeding exceeded the risk of dying from PE.

Clinical characteristics of italian patients with venous thromboembolism enrolled in the RIETE Registry

The clinical characteristics, treatment strategies and outcome of patients with venous thromboembolism (VTE) may vary from country to country. The RIETE (Registro Informatizado su la Enfermedad TromboEmbolica) is an ongoing, prospective registry of consecutive patients with acute, objectively confirmed, symptomatic VTE. Our aim was to assess the influence of surgery and immobility for non-surgical reasons on 3-month outcomes of all Italian patients registered in the RIETE. Through July 2008, 21,397 patients with acute VTE were registered in the RIETE. Of these, 896 (4.2%) were Italian, and 360 (40%) presented with pulmonary embolism (PE). Overall, 137 (15%) developed VTE after surgery; 156 (17%) developed VTE after ≥4 days of immobility, and 603 (67%) developed VTE in the absence of surgery or immobility. Most patients (83%) received initial therapy with low-molecular-weight heparin; 15% received unfractionated heparin. For long-term therapy, 63% of patients received vitamin K antagonists. The incidence of fatal PE during the first 3 months of therapy was 1.5% for patients with postoperative VTE, 7.7% for who developed VTE after immobility, and 1.2% for the remaining patients. The incidence of fatal bleeding among these patients was 1.5%, 1.9% and 0.3%, respectively. Of the 137 patients with postoperative VTE, 61% had received VTE prophylaxis. Of the 156 patients with recent immobility, 24% had received VTE prophylaxis. VTE arising after a period of immobility was associated with the highest rates of fatal PE and fatal bleeding during the first 3 months of therapy. The use of thromboprophylaxis in this population should be improved.

Clinical presentation and outcome of venous thromboembolism in COPD

Chronic obstructive pulmonary disease (COPD) is a moderate risk factor for venous thromboembolism (VTE), but neither the clinical presentation nor the outcome of VTE in COPD patients is well known. The clinical presentation of VTE, namely pulmonary embolism (PE) or deep venous thrombosis (DVT), and the outcome at 3 months (death, recurrent VTE or bleeding) were compared between 2,984 COPD patients and 25,936 non-COPD patients included in the RIETE (Registro Informatizado de la Enfermedad TromboEmbólica) registry. This ongoing international, multi-centre registry includes patients with proven symptomatic PE or DVT. PE was the more frequent VTE presentation in COPD patients (n = 1,761, 59%). PE presentation was more significantly associated with COPD patients than non-COPD patients (OR 1.64, 95% CI 1.49-1.80). During the 3-month follow-up, mortality (10.8% versus 7.6%), minor bleeding (4.5% versus 2.3%) or first VTE recurrences as PE (1.5% versus 1.1%) were significantly higher in COPD patients than in non-COPD patients. PE was the most common cause of death. COPD patients presented more frequently with PE than DVT. It may explain the worse prognosis of COPD patients, with a higher risk of death, bleeding or VTE recurrences as PE compared with non-COPD patients. Further therapeutic options are needed.

Heparin‐associated thrombocytopenia in 24 401 patients with venous thromboembolism: findings from the RIETE Registry

Whether the treatment of venous thromboembolism (VTE) with unfractionated heparin (UFH) confers a higher risk of thrombocytopenia than does treatment with low molecular weight heparin (LMWH) remains controversial, and very few data are available from routine clinical practice. We assessed the incidence, risk factors and prognosis of heparin-associated thrombocytopenia (HAT) according to the type of heparin therapy, UFH or LMWH. Data were obtained from the international prospective Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE), which included 25,369 patients with confirmed VTE until February 2009. Among them, 24,401 patients were treated either with UFH or with LMWH, and had available information about the 6-month occurrence of confirmed thrombocytopenia, defined as a platelet count ≤ 150,000 mm(-3) . One hundred and forty-one patients receiving UFH and/or LMWH developed thrombocytopenia within a 6-month period. The incidence of HAT was significantly higher in the UFH group (1.36%, 95% confidence interval [CI] 0.79-2.17) than in the LMWH group (0.54%, 95% CI 0.44-0.64). As compared with LMWH, UFH significantly increased the risk of HAT in female patients (adjusted hazard ratio [HR] 4.90%, 95% CI 2.58-9.31, P = 0.001) but not in male patients (adjusted HR 1.60%, 95% CI 0.64-3.97, P = 0.31); P = 0.027 for comparison. In each gender, the UFH-associated excess risk was confined to patients with VTE unrelated to cancer. The poor prognosis of patients with thrombocytopenia was not influenced by the type of heparin therapy. In routine clinical practice, treatment of VTE with UFH seems to confer a higher risk of thrombocytopenia than does treatment with LMWH, especially in women and non-cancerous patients.

Three Criteria for Ecological Fallacy

In a large cohort study published in Environmental Health Perspectives, Brenner et al. (2011) confirmed previous results on I-131 exposure and thyroid cancer among a Ukranian population. According to the authors, one motivation to study this association was based on evidence from ecological studies (Jacob et al. 1999) with two methodological limitations: use of grouped doses and poor control of confounding. With these new findings, evidence from ecological, case–control, and cohort studies are consistent; thus, an interesting question is whether there was an ecological fallacy. Although ecological studies are important to epidemiology (especially in environmental and social epidemiology), public health practitioners seem afraid of ecological studies. It is a common practice to assume the presence of ecological fallacy (Robinson 1950) and low-level validity when analyzing an ecological study. Most epidemiologists prefer an exclusive individualistic approach, although the importance of a multilevel causal approach is widely recognized (Diez-Roux 2002). In this sense, some authors suggest that it is as important to recognize the presence of ecological fallacy as to recognize psychologistic or individualistic fallacy (Subramanian et al. 2009) (Figure 1). Figure 1 Levels of analysys in epidemiologic studies and potential fallacies during casual inference. Thus, it is necessary to have clear guidelines on when there is or not an ecological fallacy. In this sense, I propose three criteria for the identification of ecological fallacy; all three of these should be present to confirm its existence: Results must be obtained with ecological (population) data. Data must be inferred to individuals. One use of ecological studies is to explore individual-level association when individual data are not available. When the focus of the study was contextual or based on population effects and there is no inference to individuals, ecological fallacy is not possible. When only the first two criteria are present—which is insufficient to affirm ecological fallacy—it is appropriate to acknowledge that there is a possible relationship and that further study is required. Results obtained with individual data are contradictory. Only when empirical data are available is it possible to confirm that an ecological fallacy is present.

Randomised, placebo-controlled trial to evaluate co-trimoxazole to reduce mortality and morbidity in HIV-infected post-natal women in Zambia (TOPAZ)

To evaluate the role of prophylactic trimethoprim-sulfamethoxazole (co-trimoxazole) antibacterial prophylaxis in reducing morbidity and mortality in HIV-infected post-natal women in southern Africa. Double-blind placebo-controlled trial. HIV-infected women with WHO stage 2 or 3 HIV disease who had recently delivered in the Department of Obstetrics and Gynaecology at the University Teaching Hospital, Lusaka, Zambia were randomised to receive daily co-trimoxazole (cotox) or matched placebo daily for the duration of the trial. Participants were followed up for a minimum of 1 year. Primary outcome measures were mortality from any cause or hospital admission and serious adverse events. Of 600 women randomised, follow-up information was available from 355 (180 cotox, 175 placebo) participants. Thirty-six (17 cotox, 19 placebo) women died during the trial, and another 11 (5 cotox, 6 placebo) were admitted to hospital. There was no significant difference in the combined event rates between the two treatment arms: HR = 0.82, 95% CI (0.46, 1.45), P = 0.49; morbidity was reduced over a range of symptoms. Secondary analyses of the outcome in babies indicated some evidence of reduced mortality in those whose mothers were allocated cotox. Follow-up rates were poor; there was no evidence that co-trimoxazole prophylaxis reduced mortality or hospital admission rates, although fewer symptoms were reported in the cotox arm. Cotox was safe and well tolerated.

Subtype prevalence, plasmid profiles and growing fluoroquinolone resistance in Shigella from Kolkata, India (2001-2007): a hospital-based study

Shigellosis is a major public health problem, and increasing antimicrobial resistance has complicated its treatment. We report isolation frequency, plasmid profiles and antimicrobial resistance of Shigella subtypes in Kolkata, India, from a prospective hospital-based study. Fresh stool or rectal swabs were collected from children (<5 years) attending the Diarrhea Treatment Unit of a governmental paediatric referral hospital in Kolkata. Samples were processed following standard methods over a 7-year period from January 2001 to December 2007. Of 4478 samples collected, 516 (11.5%) were positive for Shigella spp. S. flexneri (312; 6.9%) was the most frequently isolated serogroup, ranking before S. sonnei (123, 2.7%), S. dysenteriae (48, 1.1%) and S. boydii (33, 0.7%). Although 10 subtypes of S. flexneri were identified, the common ones circulating locally were S. flexneri 2a (179), S. flexneri 6 (38) and S. flexneri 3a (36). Knowledge of Shigella subtypes is important for vaccine development. The majority of Shigella isolates (81.0%) were multidrug (two or more antimicrobial classes) resistant and showed high minimum inhibitory concentration (MIC) with commonly used drugs like ampicillin, tetracycline, co-trimoxazole and nalidixic acid. Emergence of fluoroquinolone (FQ)-resistant S. dysenteriae type 1 (100.0%) in 2002-2003 was followed by frequent isolation (>25.0%) of FQ-resistant S. flexneri 2a, and S. flexneri 3a in 2004, which restricted use of fluoroquinolones for treatment. A number of smaller plasmids (<20 kb) with distinct patterns have been observed for several years in predominant subtypes. Long-term surveillance of Shigellae and their antimicrobial resistance are mandatory in endemic areas to formulate treatment policy until any suitable candidate vaccine is available to control the disease.

Pulmonary embolism in patients over 90 years of age

There is some uncertainty about the management of pulmonary embolism in nonagenarians. Immobility plays an important role in the pathogenesis of venous thromboembolism in the elderly. Of 858 nonagenarians with acute venous thromboembolism enrolled in Registro Informatizado de la Enfermedad TromboEmbolica venosa registry, 41% had recent immobility and only 7.7% had recent surgery. Comorbidity is common: 19% of patients had chronic heart failure, 9.8% chronic lung disease, 14% cancer, and 63% had abnormal creatinine levels. Most (92%) of the patients were initially treated with low-molecular-weight heparin and then 46% switched to antivitamin K drugs. During follow-up, the proportion of patients who developed recurrent venous thromboembolism (4.9%) or major bleeding complications (6.2%) was similar, but the 5.9% of fatal pulmonary embolisms by far exceeded the 2.2% of fatal bleeding events. The most common clinical symptoms are isolated dyspnea and syncope, and presentation as pulmonary infarction (with hemoptysis and pleuritic chest pain) is rare. In patients aged at least 90 years presenting with acute pulmonary embolism, the incidence of fatal pulmonary embolism by far outweighs the incidence of fatal bleeding, and pulmonary embolism is the most common cause of death. Thus, there seems to be more reason to be concerned about fatal pulmonary embolism than about bleeding in elderly patients presenting with pulmonary embolism.