Risk factors associated with malaria deaths in travellers: A literature review

[Gastrointestinal symptoms may reflect complicated falciparum malaria]

HISTORY

 A 42-year-old female presented with a two-day history of vomiting, diarrhea, fever and chills. Two weeks before she had returned to Germany from a Safari in Tanzania. She had disregarded the recommendation to take antimalarial chemoprophylaxis.

CLINICAL FINDINGS AND DIAGNOSIS

 The thin blood film showed Plasmodium falciparum-parasitized erythrocytes, and Plasmodium falciparum malaria was diagnosed. The full blood count showed thrombocytopenia and ultrasound imaging revealed splenomegaly. Initially the criteria for complicated malaria were not fulfilled.

THERAPY AND COURSE

 We started oral therapy with atovaquone/proguanil. The patient vomited the tablets twice. Therefore therapy was switched to intravenous artesunate. Subsequently, parasitemia dropped from 2.8 to 1.0 % within 22 hours. After 3 days of artesunate i. v., treatment could then be completed with oral atovaquone/proguanil, and the symptoms resolved.

CONCLUSIONS

 Patients with malaria and persistent vomiting should be treated intravenously and monitored closely, as severe gastrointestinal symptoms may reflect impending organ failure. We therefore propose including persistent vomiting in the list of criteria for complicated malaria.

Perspectives of primary care physicians in Spain on malaria: a cross-sectional survey and retrospective review of cases

BACKGROUND

In Spain, the risk of imported malaria has increased in recent years due to the rise in international travel and migration. Little is known about the knowledge, information sources, clinical practice, and specific needs of primary care physicians (PCPs) concerning malaria despite the pivotal role played by these professionals in managing the health of tourists. The objective of this study was to assess the knowledge, attitudes, and practices of PCPs in Spain regarding malaria.

METHODS

This research analyses data from (1) a cross-sectional nationwide survey assessing the knowledge and attitudes of PCPs regarding malaria, and (2) a retrospective review of 373 malaria cases appearing in primary care medical records (PCMRs) in the Madrid area over the past 15 years to determine how cases were documented, managed, or characterized in the primary care setting.

RESULTS

The survey findings reveal a modest level of self-perceived familiarity with malaria (221/360, 57.6%), even though 32.8% of the practitioners reported having delivered care for confirmed or suspected cases of the disease, these practitioners had greater knowledge of malaria (80.4%) compared to physicians who reported not having delivered care for malaria (19.6%, p < 0.001). Ten percent of the survey participants did not know the name of the mosquito that transmits malaria, and only 40.7% would promptly request malaria testing for a traveller with symptoms after a trip to an endemic area. Responses provided by younger PCPs varied to a greater extent than those of their more experienced colleagues regarding prevention practices and patient management. A review of PCMRs showed that only 65% of all patients were recorded as such. Among those registered, only 40.3% had a documented malaria episode, and of those, only 16.6% received proper follow-up. Only 23.7% of the patients with a PCMR had a record that specifically indicated travel to an endemic country or travel classified as visiting friends and relatives (VFR).

CONCLUSIONS

The findings of this study underscore the critical role of PCPs in the field of travel medicine, particularly given the increase in imported malaria cases. These results highlight the need for targeted training in travel medicine and the need to ensure optimal patient education in care settings.

Imported diseases in travellers presenting to the emergency department after a stay in a malaria-endemic country: a retrospective observational study

BACKGROUND

We aimed to investigate the aetiology and outcomes of illnesses in patients presenting to an emergency department after travelling to a malaria-endemic country, in order to raise awareness of both tropical and cosmopolitan diseases.

METHODS

A retrospective chart review was performed for all patients who underwent blood smear testing for malaria at the Emergency Department of the University Hospitals Leuven from 2017 to 2020. Patient characteristics, results of laboratory and radiological examinations, diagnoses, disease course and outcome were collected and analysed.

RESULTS

A total of 253 patients were included in the study. The majority of ill travellers returned from Sub-Saharan Africa (68.4%) and Southeast Asia (19.4%). Their diagnoses fell into three major syndrome categories: systemic febrile illness (30.8%), inflammatory syndrome of unknown origin (23.3%) and acute diarrhoea (18.2%). Malaria (15.8%) was the most common specific diagnosis in patients with systemic febrile illness, followed by influenza (5.1%), rickettsiosis (3.2%), dengue (1.6%), enteric fever (0.8%), chikungunya (0.8%) and leptospirosis (0.8%). The presence of hyperbilirubinemia and thrombocytopenia increased the probability of malaria, with a likelihood ratio of 4.01 and 6.03, respectively. Seven patients (2.8%) were treated in the intensive care unit, and none died.

CONCLUSION

Systemic febrile illness, inflammatory syndrome of unknown origin and acute diarrhoea were the three major syndromic categories in returning travellers presenting to our emergency department after a stay in a malaria-endemic country. Malaria was the most common specific diagnosis in patients with systemic febrile illness. None of the patients died.

Epidemiology and clinical features of imported malaria: a 14-year retrospective single-centre descriptive study in Prague, Czech Republic

Background

Malaria represents one of the most important imported tropical infectious diseases in European travellers. The objective of the study was to identify changes in the epidemiological features of imported malaria and to analyse the clinical findings and outcomes of imported malaria.

Methods

This single-centre descriptive study retrospectively analysed the medical records of all imported malaria cases in travellers treated at the Department of Infectious Diseases of University Hospital Bulovka in Prague from 2006 to 2019.

Results

The study included 203 patients with a median age of 37 years (IQR 30–48) and a male to female ratio of 3.72:1. Plasmodium falciparum was the predominant species (149/203), and its proportion significantly increased from 35/60 cases (58.3%) in 2006–2011 to 69/80 (86.3%) in 2016–2019 (p < 0.001). In contrast, the incidence of Plasmodium vivax malaria decreased from 19/60 cases (31.7%) in 2006–2011 to 5/80 (6.3%) in 2016–2019 (p < 0.001). Malaria was imported from sub-Saharan Africa in 161/203 cases (79.3%). The proportion of travellers from Southeast and South Asia decreased from 16/60 (26.7%) and 6/60 (10.0%) in 2006–2011 to 2/80 (2.5%) and no cases (0.0%) in 2016–2019, respectively (p < 0.001 and p = 0.006). Tourism was the most common reason for travel (82/203), however, the proportion of non-tourists significantly increased over time from 29/60 (48.3%) in 2006–2011 to 55/80 (68.8%) in 2016–2019, p = 0.015. Severe malaria developed in 32/203 (15.8%) patients who were significantly older (p = 0.013) and whose treatment was delayed (p < 0.001). Two lethal outcomes were observed during the study period.

Conclusions

This study demonstrated a significant increase in P. falciparum malaria, which frequently resulted in severe disease, especially in older patients and those with delayed treatment initiation. The rising proportion of imported malaria in non-tourists, including business travellers and those visiting friends and relatives, is another characteristic finding analogous to the trends observed in Western European and North American centres. The described changes in the aetiology and epidemiology of imported malaria may serve to optimize pre-travel consultation practices and improve post-travel diagnostics and medical care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04282-8.

Malaria time series in the extra-Amazon region of Brazil: epidemiological scenario and a two-year prediction model

BACKGROUND

In Brazil, malaria is caused mainly by the Plasmodium vivax and Plasmodium falciparum species. Its transmission occurs in endemic and non-endemic areas. Malaria geography in Brazil has retracted and is now concentrated in the North region. The Brazilian Amazon region accounts for 99% of Brazil's cases. Brazil's extra-Amazon region has a high frequency of imported cases and in 2019 presented a mortality rate 123 times higher than the Amazon region. Extra-Amazon cases present risks of reintroduction. This study aims to characterize the epidemiological scenario for malaria in the extra-Amazon region of Brazil from 2011 to 2020 with a two-year forecast.

METHODS

Time-series study with description of malaria cases and deaths registered in Brazilian extra-Amazon region from 2011 to 2020. Public data from the Notifiable Diseases Information System (Sinan) and the Mortality Information System (SIM) were used. Descriptive analysis, incidence, and notification rates were calculated. Flow charts analysed the flux between Places of Probable Infection (PI) and places of notification. The prediction model utilized a multiplicative Holt-winters model for trend and seasonality components.

RESULTS

A total of 6849 cases were registered. Cases were predominantly white males with 9 to 11 years of education, mostly between 30 and 39 years old. Imported cases accounted for 78.9% of cases. Most frequent occupations for imported cases are related to travelling and tourism activities. Among autochthonous cases, there is a higher frequency of agriculture and domestic economic activities. In the period there were 118 deaths due to malaria, of which 34.7% were caused by P. falciparum infections and 48.3% were not specified. The most intense flows of imported cases are from Amazonas and Rondônia to São Paulo, Rio de Janeiro, and Paraná. The prediction estimates around 611 cases for each of the following two years.

CONCLUSION

The time series allows a vast epidemiological visualization with a short-term prediction analysis that supports public health planning. Government actions need to be better directed in the extra-Amazon region so the objective of eliminating malaria in Brazil is achieved. Carrying out quality assessments for information systems and qualifying personnel is advisable. Malaria outside the Amazon region is mainly due to imported cases and delay in diagnosis is associated with a higher fatality rate. Better strategies to diagnose and treat suspected cases can lead to lower risk of deaths and local outbreaks that will be important for achieving malaria elimination in Brazil.

High prevalence of malaria in a non-endemic setting among febrile episodes in travellers and migrants coming from endemic areas: a retrospective analysis of a 2013-2018 cohort

Background

The study aimed to analyse the likelihood of imported malaria in people with a suggestive clinical picture and its distinctive characteristics in a hospital in the south of Madrid, Spain.

Methods

Observational retrospective study that consisted of a review of all medical files of patients with any malaria test registered at Móstoles University Hospital between April 2013 and April 2018. All suspected malaria cases were confirmed by Plasmodium spp. polymerase chain reaction (PCR).

Results

Of the 328 patients with suspected malaria (53.7% migrant-travellers; 38.7% visitors; 7.6% travellers), 108 cases were confirmed (101 by Plasmodium falciparum), accounting for a 33% positive sample rate. Sixteen cases were diagnosed only by PCR. Patients with malaria, compared to those without, presented predominantly with fever (84% vs. 65%), were older (34 vs. 24 years), sought medical attention earlier (17d vs. 32d), had a greater number of previous malaria episodes (74% vs. 60%), lower levels of platelets (110,500µL vs. 250,000µL), and higher of bilirubin (0.6 mg/dL vs. 0.5 mg/dL). Severe malaria was present in 13 cases; no deaths were recorded. Malaria diagnosis showed a bimodal distribution with two peaks: June to September and November to January.

Conclusions

Malaria is still a common diagnosis among febrile patients coming from the tropics specially among migrant travellers. Fever, thrombocytopenia, and/or high bilirubin levels should raise suspicion for this parasitic infection. Prompt diagnosis is crucial to avoid severe cases and deaths.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03984-9.

Factors Associated with Prolonged Hospital Length of Stay in Adults with Imported Falciparum Malaria-An Observational Study from a Tertiary Care University Hospital in Berlin, Germany

Outcome of falciparum malaria is largely influenced by the standard of care provided, which in turn depends on the available medical resources. Worldwide, the COVID-19 pandemic has had a major impact on the availability of these resources, even in resource-rich healthcare systems such as Germany's. The present study aimed to determine the under-explored factors associated with hospital length of stay (LOS) in imported falciparum malaria to identify potential targets for improving management. This retrospective observational study used multivariate Cox proportional hazard regression with time to discharge as an endpoint for adults hospitalized between 2001 and 2015 with imported falciparum malaria in the Charité University Hospital, Berlin. The median LOS of the 535 cases enrolled was 3 days (inter-quartile range, IQR, 3-4 days). The likelihood of being discharged by day 3 strongly decreased with severe malaria (hazard ratio, HR, 0.274; 95% Confidence interval, 95%CI: 0.190-0.396) and by 40% with each additional presenting complication (HR, 0.595; 95%CI: 0.510-0.694). The 55 (10.3%) severe cases required a median LOS of 7 days (IQR, 5-12 days). In multivariate analysis, occurrence of shock (adjusted HR, aHR, 0.438; 95%CI 0.220-0.873), acute pulmonary oedema or acute respiratory distress syndrome (aHR, 0.450; 95%CI: 0.223-0.874), and the need for renal replacement therapy (aHR, 0.170; 95%CI: 0.063-0.461) were independently associated with LOS. All patients survived to discharge. This study illustrates that favourable outcomes can be achieved with high-standard care in imported falciparum malaria. Early recognition of disease severity together with targeted supportive care can lead to avoidance of manifest organ failure, thereby potentially decreasing LOS and alleviating pressure on bed capacities.

Efficacy of a 3-day pretravel schedule of tafenoquine for malaria chemoprophylaxis: a network meta-analysis

BACKGROUND

Chemoprophylaxis with weekly doses of tafenoquine (200 mg/day for 3 days before departure [loading dose], 200 mg/week during travel and 1-week post-travel [maintenance doses]) is effective in preventing malaria. Effectiveness of malaria chemoprophylaxis drugs in travellers is often compromised by poor compliance. Shorter schedules that can be completed before travel, allowing 'drug-free holidays', could increase compliance and thus reduce travel-related malaria. In this meta-analysis, we examined if a loading dose of tafenoquine alone is effective in preventing malaria in short-term travellers.

METHODS

Four databases were searched in November 2020 for randomized controlled trials (RCTs) that assessed efficacy and/or safety of tafenoquine for chemoprophylaxis. Network meta-analysis using the generalized pair-wise modelling framework was utilized to estimate the odds ratio (OR) of malaria infection in long-term (>28 days) and short-term (≤28 days) travellers, as well as adverse events (AEs) associated with receiving loading dose of tafenoquine alone, loading dose of tafenoquine followed by maintenance doses, loading dose of mefloquine followed by maintenance doses, or placebo.

RESULTS

Nine RCTs (1714 participants) were included. In long-term travellers, compared to mefloquine, tafenoquine with maintenance doses (OR = 1.05; 95% confidence interval [CI]: 0.44-2.46) was equally effective in preventing malaria, while there was an increased risk of infection with the loading dose of tafenoquine alone (OR = 2.89; 95% CI: 0.78-10.68) and placebo (OR = 62.91; 95% CI: 8.53-463.88). In short-term travellers, loading dose of tafenoquine alone (OR = 0.98; 95% CI: 0.04-22.42) and tafenoquine with maintenance doses (OR = 1.00; 95% CI: 0.06-16.10) were as effective as mefloquine. The risk of AEs with tafenoquine with maintenance doses (OR = 1.03; 95% CI: 0.67-1.60) was similar to mefloquine, while loading dose of tafenoquine alone (OR = 0.58; 95% CI: 0.20-1.66) was associated with lower risk of AEs, although the difference was not statistically significant.

CONCLUSIONS

For short-term travellers, loading dose of tafenoquine alone was equally effective, had possibly lower rate of AEs, and likely better compliance than standard tafenoquine or mefloquine chemoprophylaxis schedules with maintenance doses. Studies are needed to confirm if short-term travellers remain free of infection after long-term follow-up.

REGISTRATION

The meta-analysis was registered in PROSPERO (CRD42021223756).

HIGHLIGHT

Tafenoquine is the latest approved drug for malaria chemoprophylaxis. A loading dose of tafenoquine (200 mg/day for 3 days before departure) is as effective in preventing malaria in short-term (≤28 days) travellers as chemoprophylaxis schedules of tafenoquine or mefloquine with maintenance doses, allowing travellers to have a 'drug-free holiday'.

Mortality from malaria in France, 2005 to 2014

Introduction

Malaria is a notifiable disease in all European Union and European Economic Area countries except Belgium and France, where only autochthonous malaria is notifiable. Although morbidity caused by malaria has been assessed, little is known about mortality incidence.

Objective

Our aim was to estimate the number of imported malaria-related deaths in hospital in metropolitan France.

Methods

We matched individual deaths reported between 1 January 2005 and 31 December 2014 to the French National Reference Centre for malaria (FNRCm) with malaria-related deaths from two other sources: the French National Registry on medical causes of death and the French national hospital discharge database. A capture–recapture method with log-linear modelling was used. Age, sex and place of death stratification were applied to remove heterogeneity.

Results

The estimated malaria-related deaths in metropolitan France during the study period were 205 (95% confidence interval (CI): 191–219). The annual mean number of malaria-related deaths was estimated at 21 (95% CI: 19–22). The FNRCm malaria-related deaths surveillance had a 38% sensitivity (95% CI: 32–44). Among 161 in-hospital individual malaria-related deaths reported from three data sources, the sex ratio (male to female) was 2.6. Median age of the patients was 57 years, ranging from 1 to 89 years.

Conclusion

The pertinent finding of this report is that malaria-related death records were significantly more complete than case records. Therefore, data comparison of imported malaria morbidity and mortality between countries should imperatively be assessed using standard indicators weighted according to the completeness of health surveillance systems.

Defining malaria risks among forest workers in Aceh, Indonesia: a formative assessment

Background

Following a dramatic decline of malaria cases in Aceh province, geographically-based reactive case detection (RACD) was recently evaluated as a tool to improve surveillance with the goal of malaria elimination. While RACD detected few cases in households surrounding index cases, engaging in forest work was identified as a risk factor for malaria and infections from Plasmodium knowlesi—a non-human primate malaria parasite—were more common than expected. This qualitative formative assessment was conducted to improve understanding of malaria risk from forest work and identify strategies for targeted surveillance among forest workers, including adapting reactive case detection.

Methods

Between June and August, 2016, five focus groups and 18 in-depth interviews with forest workers and key informants were conducted in each of four subdistricts in Aceh Besar and Aceh Jaya districts. Themes included: types of forest activities, mobility of workers, interactions with non-human primates, malaria prevention and treatment-seeking behaviours, and willingness to participate in malaria surveys at forest work sites and using peer-referral.

Results

Reported forest activities included mining, logging, and agriculture in the deep forest and along the forest fringe. Forest workers, particularly miners and loggers, described often spending weeks to months at work sites in makeshift housing, rarely utilizing mosquito prevention and, upon fever, self-medicating and seeking care from traditional healers or pharmacies rather than health facilities. Non-human primates are frequently observed near work sites, and most forest work locations are within a day’s journey of health clinics. Employers and workers expressed interest in undertaking malaria testing and in participating in survey recruitment by peer-referral and at work sites.

Conclusions

Diverse groups of forest workers in Aceh are potentially exposed to malaria through forest work. Passive surveillance and household-based screening may under-estimate malaria burden due to extended stays in the forest and health-seeking behaviours. Adapting active surveillance to specifically target forest workers through work-site screening and/or peer-referral appears promising for addressing currently undetected infections.

Self-diagnosis and self-treatment of Plasmodium spp. infection by travellers (1989-2019): A systematic review and meta-analysis

BACKGROUND

Standby emergency self-treatment (SBET) is often recommended as an anti-malaria strategy for travellers to low-risk endemic areas. This self-treatment enables competent malaria therapy, if medical assistance is unavailable. The World Health Organization (WHO) recommends performing reliable diagnostic tests before starting antimalarial treatment. For the self-diagnosis of malaria in travellers, rapid diagnostic tests (RDT) can be used to confirm the infection before SBET is used. The aim of this research is to assess the use of RDT and/or SBET in travellers.

METHODS

We searched the databases (PubMed, Scopus, Embase, CINAHL) using terms and synonyms for 'self-diagnosis' and 'self-treatment' combined with 'malaria' and 'travel'. Articles in English, French and German were included. Potential articles were screened and extracted by two authors (KU and PS). Only original articles and case reports documenting the self-use of RDT and/or SBET in travellers were included. Data were extracted using a standardised approach. We defined 'correct use' of RDT and SBET. Data on number and performance of RDT and SBET use, as well as malaria verification were collected in an Excel table. Five meta-analyses were performed using a random effects model and calculating pooled proportions. This systematic review was conducted according to the PRISMA guidelines and registered in PROSPERO (CRD42018108874).

RESULTS

The research resulted in 867 articles of possible relevance on RDT and 955 articles on SBET. After screening, a total of 4 articles on RDT use and 17 articles for SBET use in travellers were included in the systematic review. Most of the RDT were performed and interpreted properly by the travellers (pooled proportion 88%, 95% confidence interval (CI) from 64% to 97%), whereby the proportion of correct performance was increased after a pre-travel test run (97%). Major problems in the implementation such as pricking finger, placing blood drop, identifying lines and interpreting results could be discovered. We found data on 1025 SBET uses in studies of travellers to high-risk African countries. In these studies, the pooled proportion of SBET uses was 6% (95% CI from 2% to 13%). We found 545 SBET uses in studies of travellers to countries of mixed malaria risk. In these studies, the pooled proportion of SBET uses was 2% (95% CI from 1% to 7%). Furthermore, the evaluation showed a high proportion of correct SBET use (pooled proportion 69%, 95% CI from 35% to 90%). As a cause for incorrect use, errors in dosage (under- or overdose), disregard of minimal incubation period (< 7 days since first possible malaria exposure) and absence of fever were identified. Four cases of post-SBET severe adverse events were documented. In a third of travellers who used SBET, a Plasmodium spp. infection could be detected (pooled proportion 31%, 95% CI from 16% to 51%).

CONCLUSIONS

This systematic review and meta-analysis showed that the majority of travellers were able to use RDT and SBET correctly. Standardised pre-travel instructions and specific training are indicated to increase the proportions of correct RDT and SBET use. With improved and user-friendly technology, RDT may become an integral part of SBET malaria recommendations for travellers. Combined use of RDT and SBET could be an appropriate strategy for selected subgroups of travellers to low-risk, remote malaria areas. Future research should focus on combined RDT and SBET strategies.

Evaluation of the Combination of Azithromycin and Naphthoquine in Animal Malaria Models

Combination therapy using drugs with different mechanisms of action is the current state of the art in antimalarial treatment. However, except for artemisinin-based combination therapies, only a few other combinations are now available. Increasing concern regarding the emergence and spread of artemisinin resistance in Plasmodium falciparum has led to a need for the development of new antimalarials. Moreover, the efficacy of current available chemoprophylaxis is compromised by drug resistance and noncompliance due to intolerable adverse effects or complicated dosing regimens.

The risk of malaria infection for travelers visiting the Brazilian Amazonian region: A mathematical modeling approach

BACKGROUND

Human mobility between malaria endemic and malaria-free areas can hinder control and elimination efforts in the Amazon basin, maintaining Plasmodium circulation and introduction to new areas.

METHODS

The analysis begins by estimating the incidence of malaria in areas of interest. Then, the risk of infection as a function of the duration of stay after t₀ was calculated as the number of infected travelers over the number of arrived travelers. Differential equations were employed to estimate the risk of nonimmune travelers acquiring malaria in Amazonian municipalities. Risk was calculated as a result of the force of the infection in terms of local dynamics per time of arrival and duration of visit.

RESULTS

Maximum risk occurred at the peak or at the end of the rainy season and it was nonlinearly (exponentially) correlated with the fraction of infected mosquitoes. Relationship between the risk of malaria and duration of visit was linear and positively correlated. Relationship between the risk of malaria and the time of arrival in the municipality was dependent on local effects of seasonality.

CONCLUSIONS

The risk of nonimmune travelers acquiring malaria is not negligible and can maintain regional circulation of parasites, propagating introductions in areas where malaria has been eliminated.

Severity of Plasmodium falciparum and Non-falciparum Malaria in Travelers and Migrants: A Nationwide Observational Study Over 2 Decades in Sweden

Background

The aim was to assess factors affecting disease severity in imported P. falciparum and non-falciparum malaria.

Methods

We reviewed medical records from 2793/3260 (85.7%) of all episodes notified in Sweden between 1995 and 2015 and performed multivariable logistic regression.

Results

Severe malaria according to WHO 2015 criteria was found in P. falciparum (9.4%), P. vivax (7.7%), P. ovale (5.3%), P. malariae (3.3%), and mixed P. falciparum episodes (21.1%). Factors associated with severe P. falciparum malaria were age <5 years and >40 years, origin in nonendemic country, pregnancy, HIV, region of diagnosis, and health care delay. Moreover, oral treatment of P. falciparum episodes with parasitemia ≥2% without severe signs at presentation was associated with progress to severe malaria with selected criteria. In non-falciparum, age >60 years, health care delay and endemic origin were identified as risk factors for severe disease. Among patients originating in endemic countries, a higher risk for severe malaria, both P. falciparum and non-falciparum, was observed among newly arrived migrants.

Conclusions

Severe malaria was observed in P. falciparum and non-falciparum episodes. Current WHO criteria for severe malaria may need optimization to better guide the management of malaria of different species in travelers and migrants in nonendemic areas.

Hypertension is associated with an increased risk for severe imported falciparum malaria: a tertiary care hospital based observational study from Berlin, Germany

Background

Increasing numbers of aging individuals with chronic co-morbidities travel to regions where falciparum malaria is endemic. Non-communicable diseases are now leading risk factors for death in such countries. Thus, the influence of chronic diseases on the outcome of falciparum malaria is an issue of major importance. Aim of the present study was to assess whether non-communicable diseases increase the risk for severe imported falciparum malaria.

Methods

A retrospective observational study of all adult cases with imported falciparum malaria hospitalized between 2001 and 2015 in the tertiary care Charité University Hospital, Berlin, was performed.

Results

A total of 536 adult patients (median age 37 years; 31.3% female) were enrolled. Of these, 329 (61.4%) originated from endemic countries, 207 patients (38.6%) from non-endemic regions. Criteria for severe malaria were fulfilled in 68 (12.7%) cases. With older age, lack of previous malaria episodes, being a tourist, and delayed presentation, well-characterized risk factors were associated with severe malaria in univariate analysis. After adjustment for these potential confounders hypertension (adjusted odds ratio aOR, 3.06 95% confidence interval, CI 1.34–7.02), cardiovascular diseases (aOR, 8.20 95% CI 2.30–29.22), and dyslipidaemia (aOR, 6.08 95% CI 1.13–32.88) were individual diseases associated with severe disease in multivariable logistic regression. Hypertension proved an independent risk factor among individuals of endemic (aOR, 4.83, 95% CI 1.44–16.22) as well as of non-endemic origin (aOR, 3.60 95% CI 1.05–12.35).

Conclusions

In imported falciparum malaria hypertension and its related diseases are risk factors for severe disease.

Imported malaria cases: the connection with the European ex-colonies

Background

Imported malaria is increasing in non-endemic areas due to the increment of international travels, migration and, probably, other unknown factors. The objective of this study was to describe the epidemiological and clinical characteristics of malaria cases in a region of Spain; analyse the possible association between the variables of interest; compare this series with others; and evaluate the characteristics of imported malaria cases according to the country of origin, particularly cases from Equatorial Guinea (Spanish ex-colony) and from the rest of sub-Saharan Africa.

Methods

A descriptive observational study was carried out with a retrospective data collection of cases of malaria reported in Aragon from 1996 to 2017. Univariate and bivariate analysis of clinical–epidemiological variables was performed. In addition, an analysis of cases from sub-Saharan Africa was carried out using logistic regression, calculating odds ratio with its 95% confidence interval.

Results

609 cases of malaria were recorded in Aragon from 1996 to 2017. An autochthonous case in 2010. 50.33% were between 15 and 39 years old. 45.65% of the cases were notified of the 4-weeks 9 to 12. 82.6% reside in the main province, urban area, of which 65.4% were VFR (Visiting Friends and Relatives), 23.8% new immigrants and 10.9% travellers. The infectious Plasmodium species par excellence was Plasmodium falciparum (88%). Analysing the cases from sub-Saharan Africa (95.2% of the total), 48.1% were from Equatorial Guinea. Comparing these with the cases from the rest of sub-Saharan Africa, it was observed that the cases from the Spanish ex-colony have association with the female gender, being under 5 years old, residing in the main province (urban area) and being a new immigrant.

Conclusions

The epidemiological profile of imported malaria cases can be defined as VFR between 15 and 39 years old, coming from sub-Saharan Africa, particularly from Equatorial Guinea. Immigrants education about the importance of chemoprophylaxis when travelling to visit friends and relatives, emphasizing on those who are originally from the ex-colonies of destination country, is necessary; as well as to raise awareness among health professionals to make advice in consultations, specially before summer vacations.

Malaria standby emergency treatment (SBET) for travellers visiting malaria endemic areas: a systematic review and meta-analysis

BACKGROUND

Malaria prevention methods for travellers to low or moderate malaria risk areas vary and remain controversial. Standby emergency treatment (SBET) for malaria is one possible strategy increasingly recommended since 1988 with little evidence on its effectiveness or how it is truly being used.

METHODS

A systematic review and meta-analysis were performed based on a structured search in Embase, Medline, PubMed, Cochrane and Web of Science on 7 September 2018. The primary outcome was the overall prevalence of SBET use in travellers, and secondary outcomes were the proportion carrying SBET, the response to fever [use of SBET, health facility attendance and use of malaria rapid diagnostic test (mRDT)], adverse events to SBET and the proportion using SBET incorrectly (incorrect dosage/duration). The pooled SBET use prevalence was analysed using a random effects model. A descriptive summary was done to present secondary outcomes. The study protocol was registered with PROSPERO CRD42018103703.

RESULTS

A total of 11 studies were eligible for inclusion among the 1027 titles identified by our search. The studies included 7/11 prospective cohort studies that recruited pre-travel clinic attendees in Europe and 4/11 cross-sectional studies, of which 3 recruited travellers at airports before their return home from Southeast Asia and Africa and 1 from an employee registry including long-term travellers. The overall pooled prevalence of SBET use among the 26 403 travellers was 2.5% (95% confidence interval, 1.1-4.3%; range, 0.4-10.8%). There was significant variation in the proportion of travellers carrying SBET medication (40-100%), the proportion of travellers with appropriate response to fever (23-100%), adverse events (0-33%) and incorrect dosage/duration of SBET (0-100%).

CONCLUSION

Adherence to the proposed recommendations for SBET use, notably the response to fever, was poor. If the use of SBET is to be pursued, modifications to the current SBET strategy should be considered, such as better selection of travellers at higher risk for malaria and the potential addition of mRDTs.

Severe vivax malaria in the Republic of Korea during the period 2000 to 2016

BACKGROUND

There has been a marked increase in the reporting of confirmed vivax malaria cases in certain geographical areas. This study investigated cases of severe vivax malaria in the Republic of Korea.

METHODS

We retrospectively reviewed the medical records of adult patients diagnosed with vivax malaria in the Republic of Korea during the period 2000 to 2016. Diagnosis was made using the World Health Organization criteria, with the exception of parasite density.

RESULTS

Among 1366 malaria cases, 255 (18.7%) were classified as severe vivax malaria, and 46 (3.4%) required intensive care. None of patients died of malaria. Patients with severe vivax malaria were older and had more comorbidity. The enrollment periods were classified into three groups, 2000 to 2005 (506 cases), 2006 to 2010 (696 cases), and 2011 to 2016 (304 cases). Malaria cases decreased from 2011 to 2016, but severe malaria cases increased significantly over time (14.3%, 20.1%, and 22.8%, p = 0.003). Common severe manifestations were shock (45.6%) and jaundice (43.1%).

CONCLUSIONS

Cases of severe malaria increased, and shock and jaundice were the predominant findings of severe vivax malaria in the Republic of Korea.

New hybrid trifluoromethylquinolines as antiplasmodium agents

Malaria remains a major public health problem worldwide, and it is responsible for high rates of morbidity and mortality. Resistance to current antimalarial drugs has been identified, and new drugs are urgently needed. In this study, we designed and synthesized seventeen novel quinolines based on the structures of mefloquine ((2,8-bis(trifluoromethyl)quinolin-4-yl)(piperidin-2-yl)methanol) and amodiaquine (4-((7-chloroquinolin-4-yl)amino)-2-((diethylamino)methyl)phenol) using ring bioisosteric replacement and molecular hybridization of the functional groups. The compounds were evaluated in vitro against Plasmodium falciparum and in vivo in mice infected with P. berghei. All derivatives presented anti-P. falciparum activity with IC₅₀ values ranging from 0.083 to 33.0 µM. The compound with the best anti-P. falciparum activity was N-(5-methyl-4H-1,2,4-triazol-3-yl)-2,8-bis(trifluoromethyl)quinolin-4-amine (12) which showed an IC₅₀ of 0.083 µM. The three most active compounds were selected for antimalarial activity tests against P. berghei-infected mice. Compound 12 was the most active on the 5th day after infection, reducing parasitemia by 66%, which is consistent with its in vitro activity. This is an important result as 12, a simpler molecule than mefloquine, does not contain the stereogenic center, and consequently, its synthesis in the laboratory is easier and less expensive. This system proved promising for the design of potential antimalarial compounds.

A challenging entanglement: health care providers' perspectives on caring for ill and injured tourists on Cozumel Island, Mexico

Purpose: Despite established knowledge that tourists often fall ill or are injured abroad, little is known about their treatment. The intent of this study was to explore health care professionals’ treatment provision experiences on Cozumel Island, Mexico. Methods: 13 semi-structured interviews were undertaken with professionals across a number of health care vocations on Cozumel Island. Interviews were transcribed and thematically analysed to determine common challenges faced in the provision of treatment for transnational tourists. Results: Three thematic challenges emerged from the data: human and physical resource deficiencies, medical (mis)perceptions held by patients and complexities surrounding remuneration of care. Health care providers employ unique strategies to mitigate these challenges. Conclusion: Although many of these challenges exist within other touristic and peripheral spaces, we suggest that the challenges experienced by Cozumel Island’s health care professionals, and their mitigation strategies, exist as part of a complex entanglement between the island’s health care sector and its dominant tourism landscape. We call on tangential tourism services to take a larger role in ensuring the ease of access to, and provision of quality health care services for tourists on Cozumel Island.

Obesity and Diabetes as Risk Factors for Severe Plasmodium falciparum Malaria: Results From a Swedish Nationwide Study

BACKGROUND

Noncommunicable diseases and obesity are increasing in prevalence globally, also in populations at risk of malaria. We sought to investigate if comorbidity, in terms of chronic diseases and obesity, is associated with severe Plasmodium falciparum malaria.

METHODS

We performed a retrospective observational study in adults (≥18 years of age) diagnosed with malaria in Sweden between January 1995 and May 2015. We identified cases through the surveillance database at the Public Health Agency of Sweden and reviewed clinical data from 18 hospitals. Multivariable logistic regression was used to assess associations between comorbidities and severe malaria.

RESULTS

Among 937 adults (median age, 37 years; 66.5% were male), patients with severe malaria had higher prevalence of chronic diseases (28/92 [30.4%]) compared with nonsevere cases (151/845 [17.9%]) (P = .004). Charlson comorbidity score ≥1 was associated with severe malaria (adjusted odds ratio [aOR], 2.63 [95% confidence interval {CI}, 1.45-4.77), as was diabetes among individual diagnoses (aOR, 2.98 [95% CI, 1.25-7.09]). Median body mass index was higher among severe (29.3 kg/m2) than nonsevere cases (24.7 kg/m2) (P < .001). Obesity was strongly associated with severe malaria, both independently (aOR, 5.58 [95% CI, 2.03-15.36]) and in combination with an additional metabolic risk factor (hypertension, dyslipidemia, or diabetes) (aOR, 6.54 [95% CI, 1.87-22.88]). The associations were observed among nonimmune travelers as well as immigrants from endemic areas.

CONCLUSIONS

Comorbidities, specifically obesity and diabetes, are previously unidentified risk factors for severe malaria in adults diagnosed with P. falciparum. Noncommunicable diseases should be considered in the acute management and prevention of malaria.

A study on the epidemiological characteristics and infectious forecast model of malaria at Guangzhou Airport among Chinese returnees from Africa

BACKGROUND

Cross-border malaria transmission in China is a major component of Chinese imported malaria cases. Such cases mostly are travellers returning from malaria endemic countries in Africa. By investigating malaria infectious status among Chinese worker in Africa, this study analysed the malaria risk factors, in order to establish infectious forecast model.

METHODS

Chinese returnees data from Africa were collected at Guangzhou Baiyun International Airport, Guangzhou, China between August 2015 and March 2016 and were included in the cross-sectional and retrospective survey.

RESULTS

A total of 1492 respondents were included in the study with the majority consisting of junior middle school educated male. Most of them are manual and technical workers hired by companies, with average of 37.04 years of age. Overall malaria incidence rate of the population was 8.98% (134/1492), and there were no significant differences regarding age, gender, occupation, or team. Forecast model was developed on the basis of malaria risk factors including working country, local ecological environment type, work duration and intensity of mosquito bite prevention.

CONCLUSIONS

The survey suggested that malaria incidence was high among Chinese travellers who had worked in Africa countries of heavy malaria burden. Further research on the frequency and severity of clinical episodes among Chinese travellers having worked in Africa is needed.

A cross-sectional analysis of traditional medicine use for malaria alongside free antimalarial drugs treatment amongst adults in high-risk malaria endemic provinces of Indonesia

Background

The level of traditional medicine use, particularly Jamu use, in Indonesia is substantial. Indonesians do not always seek timely treatment for malaria and may seek self-medication via traditional medicine. This paper reports findings from the first focused analyses of traditional medicine use for malaria in Indonesia and the first such analyses worldwide to draw upon a large sample of respondents across high-risk malaria endemic areas.

Methods

A sub-study of the Indonesia Basic Health Research/Riskesdas Study 2010 focused on 12,226 adults aged 15 years and above residing in high-risk malaria-endemic provinces. Logistic regression was undertaken to determine the significant associations for traditional medicine use for malaria symptoms.

Findings

Approximately one in five respondents use traditional medicine for malaria symptoms and the vast majority experiencing multiple episodes of malaria use traditional medicine alongside free antimalarial drug treatments. Respondents consuming traditional medicine for general health/common illness purposes every day (odds ratio: 3.75, 95% Confidence Interval: 2.93 4.79), those without a hospital in local vicinity (odds ratio: 1.31, 95% Confidence Interval: 1.10 1.57), and those living in poorer quality housing, were more likely to use traditional medicine for malaria symptoms.

Conclusion

A substantial percentage of those with malaria symptoms utilize traditional medicine for treating their malaria symptoms. In order to promote safe and effective malaria treatment, all providing malaria care in Indonesia need to enquire with their patients about possible traditional medicine use.

Malaria in travellers returning or migrating to Canada: surveillance report from CanTravNet surveillance data, 2004-2014

BACKGROUND

Malaria remains the most common specific cause of fever in returned travellers and can be life-threatening. We examined demographic and travel correlates of malaria among Canadian travellers and immigrants to identify groups for targeted pretravel intervention.

METHODS

Descriptive data on ill returned Canadian travellers and immigrants presenting to a CanTravNet site between 2004 and 2014 with a diagnosis of malaria were analyzed. Data were collected using the GeoSentinel data platform. This network comprises 63 specialized travel and tropical medicine clinics, including 7 Canadian sites (Vancouver, Calgary, Toronto, Ottawa, Winnipeg and Montréal), that contribute anonymous, delinked, clinician- and questionnaire-based travel surveillance data on all ill travellers examined to a centralized Structure Query Language database.

RESULTS

During the study period, 20 345 travellers and immigrants were evaluated, and 93% had a travel-related diagnosis. Of these, 437 (2.1%) patients received 456 malaria diagnoses, the most common species being Plasmodium falciparum (n = 282, 61.8%). People travelling to visit friends and relatives were most well-represented (n = 169, 38.7%), followed by business travellers (n = 71, 16.2%). Sub-Saharan Africa was the most common source region, accounting for 341 (74.8%) malaria diagnoses, followed by South Central Asia (n = 55, 12%). Nigeria was the most well-represented source country, accounting for 41 cases (9.0%). India, a high-volume destination for Canadians, accounted for 40 cases (8.8%), 36 of which were caused by Plasmodium vivax. Of 456 malaria diagnoses, 26 (5.7%) were severe. Of 377 nonimmigrant travellers with malaria, 19.9% (n = 75) travelled for less than 2 weeks, and 7.2% (n = 27) travelled for less than 1 week.

INTERPRETATION

This analysis provides an epidemiologic framework for Canadian practitioners encountering prospective and returned travellers. It confirms the importance of preventive measures and surveillance associated with travel to sub-Saharan Africa and India, particularly by travellers visiting friends or relatives. Short-duration travel confers important malaria risk.

Hospitalization and ambulatory care in imported-malaria: evaluation of trends and impact on mortality. A prospective multicentric 14-year observational study

BACKGROUND

Hospitalization is usually recommended for imported malaria. The goal of the present study is to evaluate the evolution in clinical pathways while measuring their impact on mortality.

METHODS

This is a 14-year prospective observational study divided into three periods. We evaluated for adult (≥15 years) and paediatric (<15 years) case trends in severity, clinical pathways (hospitalization in medical ward (MW) or intensive care unit (ICU), ambulatory care) and mortality.

RESULTS

In total, 21,386 imported malaria cases were included, 4269 of them were paediatrics (20 %). Rises in severe forms for adults [from 8 % in period 1-14 % in period 3 (p = 0.0001)] and paediatrics [from 12 to 18 % (p < 0.0001)] were found. For adults, MW admission rates decreased [-15 % (CI 95 % -17; -13)] while ambulatory care [+7 % (CI 95 % 5-9)] and ICU admission rates [+4 % (CI 95 % 3-5)] increased. For paediatrics, increase in ICU admissions (+3 %) was shown. We did not observe any change in overall mortality during the study periods, whether among adults or children, regardless of care pathway.

CONCLUSIONS

The present study indicates a changing management of imported malaria in adults, with an increasing trend for ambulatory care. The absence of change in mortality for adults indicates that ambulatory care can be proposed for adults presenting non-severe imported malaria.

Altitude training for elite endurance athletes: A review for the travel medicine practitioner

High altitude training is regarded as an integral component of modern athletic preparation, especially for endurance sports such as middle and long distance running. It has rapidly achieved popularity among elite endurance athletes and their coaches. Increased hypoxic stress at altitude facilitates key physiological adaptations within the athlete, which in turn may lead to improvements in sea-level athletic performance. Despite much research in this area to date, the exact mechanisms which underlie such improvements remain to be fully elucidated. This review describes the current understanding of physiological adaptation to high altitude training and its implications for athletic performance. It also discusses the rationale and main effects of different training models currently employed to maximise performance. Athletes who travel to altitude for training purposes are at risk of suffering the detrimental effects of altitude. Altitude illness, weight loss, immune suppression and sleep disturbance may serve to limit athletic performance. This review provides an overview of potential problems which an athlete may experience at altitude, and offers specific training recommendations so that these detrimental effects are minimised.

International Air Travel to Ohio, USA, and the Impact on Malaria, Influenza, and Hepatitis A

The State of Ohio led the United States in measles in 2014, ostensibly related to international air travel (IAT), and ranked lower than 43 other states in infectious disease outbreak preparedness. We conducted a retrospective cohort study using surveillance data of the total Ohio population of 11 million from 2010 through 2014 with a nested case control of air travelers to determine the risk of malaria, seasonal influenza hospitalizations (IH), and hepatitis A (HA) disease related to international travel and to estimate the association with domestic enplanement. IAT appeared protective for HA and IH with a risk of 0.031 (.02-.04) but for malaria was 2.7 (2.07-3.62). Enplanement increased the risk for nonendemic M 3.5 (2.5-4.9) and for HA and IH 1.39 (1.34-1.44). IAT's ratio of relative risk (RRR) of malaria to HA and IH was 87.1 (55.8-136) greater than 219 times versus domestic enplanement which was protective for malaria at 0.397 (0.282-0.559). Malaria is correlated with IAT with cases increasing by 6.9 for every 10,000 passports issued.

Malaria in the returning older traveler

BACKGROUND

Increased co-morbidities and physiological changes mean older patients may be at higher risk of adverse outcomes from certain imported illnesses. One of the most commonly diagnosed imported infections in returning travelers is malaria. Increasing age is strongly and independently associated with increasing morbidity and mortality from malaria. Delayed diagnosis leads to higher risks of poor clinical outcomes in older patients presenting with malaria. The objective of this study was to quantify malaria presentations in older patients as a percentage of total malaria presentations, compare length of hospital stay (LOS) between the older and younger cohort, and to describe medical co-morbidities, length of time to diagnosis and factors contributing to delayed diagnosis and increased LOS in the older cohort.

METHODS

A retrospective cohort study was undertaken in two university hospitals of all patients aged 65 years or older presenting with malaria from 2002-2012. A national hospital inpatient database was used to identify patients of all ages with a discharge diagnosis of malaria over this ten year period, and quantify LOS in those aged <65 and those aged 65 years or older. The case-notes for all of the older cohort were reviewed.

RESULTS

There were a total of 203 cases, 12 of whom were aged ≥65 years (5.9 %- total). Median time to diagnosis in this older group was two days (range 0-35), median LOS was eight days (range 1-77), compared to a median LOS of three days in those aged <65 years. All patients aged ≥65 years presented with fever. Travel history was documented in only 6/12 charts, and 11/12 had two or more co-morbid illnesses. Six of the 12 patients were not diagnosed or treated within 48 h of presentation.

CONCLUSIONS

This case series highlights the need for appropriate history-taking and timely diagnosis of the older traveler returning with fever, as delayed diagnosis and treatment can contribute to prolonged hospital stay and increased morbidity. With increasing numbers of older travelers, physicians must remain vigilant to the presence of imported illnesses, particularly malaria, in older patients with unexplained fever.

Clustering symptoms of non-severe malaria in semi-immune Amazonian patients

Malaria is a disease that generates a broad spectrum of clinical features. The purpose of this study was to evaluate the clinical spectrum of malaria in semi-immune populations. Patients were recruited in Mâncio Lima, a city situated in the Brazilian Amazon region. The study included 171 malaria cases, which were diagnosed via the use of a thick blood smear and confirmed by molecular methods. A questionnaire addressing 19 common symptoms was administered to all patients. Multiple correspondence analysis and hierarchical cluster analysis were performed to identify clusters of symptoms, and logistic regression was used to identify factors associated with the occurrence of symptoms. The cluster analysis revealed five groups of symptoms: the first cluster, which included algic- and fever-related symptoms, occurred in up to 95.3% of the cases. The second cluster, which comprised gastric symptoms (nausea, abdominal pain, inappetence, and bitter mouth), occurred in frequencies that ranged between 35.1% and 42.7%, and at least one of these symptoms was observed in 71.9% of the subjects. All respiratory symptoms were clustered and occurred in 42.7% of the malaria cases, and diarrhea occurred in 9.9% of the cases. Symptoms constituting the fifth cluster were vomiting and pallor, with a 14.6% and 11.7% of prevalence, respectively. A higher parasitemia count (more than 300 parasites/mm(3)) was associated with the presence of fever, vomiting, dizziness, and weakness (P < 0.05). Arthralgia and myalgia were associated with patients over the age of 14 years (P < 0.001). Having experienced at least eight malaria episodes prior to the study was associated with a decreased risk of chills and fever and an increased risk of sore throat (P < 0.05). None of the symptoms showed an association with gender or with species of Plasmodium. The clinical spectrum of malaria in semi-immune individuals can have a broad range of symptoms, the frequency and intensity of which are associated with age, past exposure to malaria, and parasitemia. Understanding the full spectrum of nonsevere malaria is important in endemic areas to guide both passive and active case detection, for the diagnosis of malaria in travelers returning to non-endemic areas, and for the development of vaccines aimed to decrease symptom severity.

Studies on Immunogenicity and Antigenicity of Baculovirus-Expressed Binding Region of Plasmodium falciparum EBA-140 Merozoite Ligand

The erythrocyte binding ligand 140 (EBA-140) is a member of the Plasmodium falciparum erythrocyte binding antigens (EBA) family, which are considered as prospective candidates for malaria vaccine development. EBA proteins were identified as important targets for naturally acquired inhibitory antibodies. Natural antibody response against EBA-140 ligand was found in individuals living in malaria-endemic areas. The EBA-140 ligand is a paralogue of the well-characterized P. falciparum EBA-175 protein. They both share homology of domain structure, including the binding region (Region II), which consists of two homologous F1 and F2 domains and is responsible for ligand-erythrocyte receptor interaction during merozoite invasion. It was shown that the erythrocyte receptor for EBA-140 ligand is glycophorin C-a minor human erythrocyte sialoglycoprotein. In studies on the immunogenicity of P. falciparum EBA ligands, the recombinant proteins are of great importance. In this report, we have demonstrated that the recombinant baculovirus-obtained EBA-140 Region II is immunogenic and antigenic. It can raise specific antibodies in rabbits, and it is recognized by natural antibodies present in sera of patients with malaria, and thus, it may be considered for inclusion in multicomponent blood-stage vaccines.

An imported case of severe falciparum malaria with prolonged hemolytic anemia clinically mimicking a coinfection with babesiosis

While imported falciparum malaria has been increasingly reported in recent years in Korea, clinicians have difficulties in making a clinical diagnosis as well as in having accessibility to effective anti-malarial agents. Here we describe an unusual case of imported falciparum malaria with severe hemolytic anemia lasting over 2 weeks, clinically mimicking a coinfection with babesiosis. A 48-year old Korean man was diagnosed with severe falciparum malaria in France after traveling to the Republic of Benin, West Africa. He received a 1-day course of intravenous artesunate and a 7-day course of Malarone (atovaquone/proguanil) with supportive hemodialysis. Coming back to Korea 5 days after discharge, he was readmitted due to recurrent fever, and further treated with Malarone for 3 days. Both the peripheral blood smears and PCR test were positive for Plasmodium falciparum. However, he had prolonged severe hemolytic anemia (Hb 5.6 g/dl). Therefore, 10 days after the hospitalization, Babesia was considered to be potentially coinfected. A 7-day course of Malarone and azithromycin was empirically started. He became afebrile within 3 days of this babesiosis treatment, and hemolytic anemia profiles began to improve at the completion of the treatment. He has remained stable since his discharge. Unexpectedly, the PCR assays failed to detect DNA of Babesia spp. from blood. In addition, during the retrospective review of the case, the artesunate-induced delayed hemolytic anemia was considered as an alternative cause of the unexplained hemolytic anemia.

In vitro and in vivo anti-malarial activity of tigecycline, a glycylcycline antibiotic, in combination with chloroquine

BACKGROUND

Several antibiotics have shown promising anti-malarial effects and have been useful for malarial chemotherapy, particularly in combination with standard anti-malarial drugs. Tigecycline, a semi-synthetic derivative of minocycline with a unique and novel mechanism of action, is the first clinically available drug in a new class of glycylcycline antibiotics.

METHODS

Tigecycline was tested in vitro against chloroquine (CQ)-sensitive (D6) and resistant strains (W2) of Plasmodium falciparum alone and in combination with CQ. Tigecycline was also tested in vivo in combination with CQ in Plasmodium berghei-mouse malaria model for parasitaemia suppression, survival and cure of the malaria infection.

RESULTS

Tigecycline was significantly more active against CQ-resistant (W2) than CQ-susceptible (D6) strain of P. falciparum. Tigecycline potentiated the anti-malarial action of CQ against the CQ-resistant strain of P. falciparum by more than seven-fold. Further, treatment of mice infected with P. berghei with tigecycline (ip) produced significant suppression in parasitaemia development and also prolonged the mean survival time. Treatment with as low as 3.7 mg/kg dose of tigecycline, once daily for four days, produced 77-91% suppression in parasitaemia. In vivo treatment with tigecycline in combination with subcurative doses of CQ produced complete cure in P. berghei-infected mice.

CONCLUSION

Results indicate prominent anti-malarial action of tigecycline in vitro and in vivo in combination with CQ and support further evaluation of tigecycline as a potential combination candidate for treatment of drug-resistant cases of malaria.