Epidemiology Of Imported Plasmodium Falciparum Infections In Returning Travelers To Calgary, 2007-2012
Bibliographic record
Abstract
INTRODUCTION Malaria, an infectious disease transmitted by the anopheles mosquitoes, contributes to the significant morbidity and mortality in the tropics - it is responsible for over three million annual deaths 1 . With the increase in intercontinental travelling and immigration, there has been a notable rise in the number of malaria cases in industrialized countries 2 . The most prevalent imported malaria cases are caused by Plasmodium falciparum species, which is also responsible for the most virulent and lethal malaria infections in humans 1 . Calgary is the fourth largest Canadian city to have the highest number of immigrants, who consisted 30% of the total city population in 2010 3 . On average, sixty to hundred malaria cases are reported annually in Calgary as determined by the local diagnostic laboratory 3 . However, little is known about the epidemiology of the patients, such as travel history, type of prophylaxis taken and the causative Plasmodium species. Therefore, the aim of this retrospective study was to determine whether returning travellers to Calgary are vectors of drug-resistant strains of malaria and thus a critical sentinel of emerging resistance in other parts of the world. METHODS The study group comprised of patients who were positive for P. falciparum malaria between 2007 and 2012 with travel history to endemic countries. The following information was collected: pre-travel advice, reason for travel, countries with malaria visited, types of prophylaxis taken and treatment. The data were entered and stored on the Microsoft Access database. From this, the following epidemiological data were collected: gender, age, geometric mean parasitemia and parasite clearance rate. The data were calculated using SPSS, Microsoft Excel and Parasite Clearance Estimator tool by WWARN. RESULTS Between 2007 and 2012, a total of 209 cases were laboratory-confirmed in Calgary. The 58.6% of the cases were caused by P. falciparum with 119 reported cases where 68.9% were seen in males. The mean age of P.falciparum infected males was 32.5±14.1 and females, 26.5±15.0. The parasite clearance rate of eligible patients ranged from 0.0269 to 0.578 (n=31). The highest GMP of 0.878 was observed in 2007. A majority of travellers received pre-travel advice (61.3%), but 38.7% of infected patients had not taken prophylaxis. Almost a half of the patients (47.5%) were VFR travellers. Most P. falciparum infected patients had travelled to at least one country in Africa. DISCUSSION AND CONCLUSIONS During the 2007 and 2012 period, there was a moderate increase in the number of P. falciparum cases, with alternating increases and decreases each year. A linear regression performed by SPSS showed that there is a non-significant (p=0.149) but a moderately increasing trend (r=0.514) in the number of P.falciparum cases over the six years. Based on the results, the majority of patients infected with P. falciparum were, therefore: males aged 30-39, travelled to Africa to VFR, did not seek pre-travel advice, did not take prophylaxis and had an average parasite clearance rate of 0.116±0.101. One limitation of this study is the estimation of parasite clearance rate, in which the tool developed by WWARN had very specific requirements and reducing the number of eligible patients to 31.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".