Malaria prevention recommendations for risk groups visiting sub-Saharan Africa: A survey of European expert opinion and international recommendations

Mathematical modeling of malaria transmission dynamics in humans with mobility and control states

Malaria importation is one of the hypothetical drivers of malaria transmission dynamics across the globe. Several studies on malaria importation focused on the effect of the use of conventional malaria control strategies as approved by the World Health Organization (WHO) on malaria transmission dynamics but did not capture the effect of the use of traditional malaria control strategies by vigilant humans. In order to handle the aforementioned situation, a novel system of Ordinary Differential Equations (ODEs) was developed comprising the human and the malaria vector compartments. Analysis of the system was carried out to assess its quantitative properties. The novel computational algorithm used to solve the developed system of ODEs was implemented and benchmarked with the existing Runge-Kutta numerical solution method. Furthermore, simulations of different vigilant conditions useful to control malaria were carried out. The novel system of malaria models was well-posed and epidemiologically meaningful based on its quantitative properties. The novel algorithm performed relatively better in terms of model simulation accuracy than Runge-Kutta. At the best model-fit condition of 98% vigilance to the use of conventional and traditional malaria control strategies, this study revealed that malaria importation has a persistent impact on malaria transmission dynamics. In lieu of this, this study opined that total vigilance to the use of the WHO-approved and traditional malaria management tools would be the most effective control strategy against malaria importation.

Exploring public awareness of the current and future malaria risk zones in South Africa under climate change: a pilot study

Although only a small proportion of the landmass of South Africa is classified as high risk for malaria, the country experiences on-going challenges relating to malaria outbreaks. Climate change poses a growing threat to this already dire situation. While considerable effort has been placed in public health campaigns in the highest-risk regions, and national malaria maps are updated to account for changing climate, malaria cases have increased. This pilot study considers the sub-population of South Africans who reside outside of the malaria area, yet have the means to travel into this high-risk region for vacation. Through the lens of the governmental "ABC of malaria prevention", we explore this sub-population's awareness of the current boundaries to the malaria area, perceptions of the future boundary under climate change, and their risk-taking behaviours relating to malaria transmission. Findings reveal that although respondents self-report a high level of awareness regarding malaria, and their boundary maps reveal the broad pattern of risk distribution, their specifics on details are lacking. This includes over-estimating both the current and future boundaries, beyond the realms of climate-topographic possibility. Despite over-estimating the region of malaria risk, the respondents reveal an alarming lack of caution when travelling to malaria areas. Despite being indicated for high-risk malaria areas, the majority of respondents did not use chemoprophylaxis, and many relied on far less-effective measures. This may in part be due to respondents relying on information from friends and family, rather than medical or governmental advice.

Targeted deep amplicon sequencing of kelch 13 and cytochrome b in Plasmodium falciparum isolates from an endemic African country using the Malaria Resistance Surveillance (MaRS) protocol

Background

Routine molecular surveillance for imported drug-resistant malaria parasites to the USA and European Union is an important public health activity. The obtained molecular data are used to help keep chemoprophylaxis and treatment guidelines up to date for persons traveling to malaria endemic countries. Recent advances in next-generation sequencing (NGS) technologies provide a new and effective way of tracking malaria drug-resistant parasites.

Methods

As part of a technology transfer arrangement between the CDC Malaria Branch and the Istituto Superiore di Sanità (ISS), Rome, Italy, the recently described Malaria Resistance Surveillance (MaRS) protocol was used to genotype 148 Plasmodium falciparum isolates from Eritrea for kelch 13 (k13) and cytochrome b (cytb) genes, molecular markers associated with resistance to artemisinin (ART) and atovaquone/proguanil (AP), respectively.

Results

Spanning the full-length k13 gene, seven non-synonymous single nucleotide polymorphisms (SNPs) were found (K189N, K189T, E208K, D281V, E401Q, R622I and T535M), of which none have been associated with artemisinin resistance. No mutations were found in cytochrome b.

Conclusion

All patients successfully genotyped carried parasites susceptible to ART and AP treatment. Future studies between CDC Malaria Branch and ISS are planned to expand the MaRS system, including data sharing, in an effort to maintain up to date treatment guidelines for travelers to malaria endemic countries.

Imported Malaria in Countries where Malaria Is Not Endemic: a Comparison of Semi-immune and Nonimmune Travelers

The continuous increase in long-distance travel and recent large migratory movements have changed the epidemiological characteristics of imported malaria in countries where malaria is not endemic (here termed non-malaria-endemic countries). While malaria was primarily imported to nonendemic countries by returning travelers, the proportion of immigrants from malaria-endemic regions and travelers visiting friends and relatives (VFRs) in malaria-endemic countries has continued to increase. VFRs and immigrants from malaria-endemic countries now make up the majority of malaria patients in many nonendemic countries. Importantly, this group is characterized by various degrees of semi-immunity to malaria, resulting from repeated exposure to infection and a gradual decline of protection as a result of prolonged residence in non-malaria-endemic regions. Most studies indicate an effect of naturally acquired immunity in VFRs, leading to differences in the parasitological features, clinical manifestation, and odds for severe malaria and clinical complications between immune VFRs and nonimmune returning travelers. There are no valid data indicating evidence for differing algorithms for chemoprophylaxis or antimalarial treatment in semi-immune versus nonimmune malaria patients. So far, no robust biomarkers exist that properly reflect anti-parasite or clinical immunity. Until they are found, researchers should rigorously stratify their study results using surrogate markers, such as duration of time spent outside a malaria-endemic country.

Adherence to recommendations at a Canadian tertiary care Family Travel Clinic - A single centre analysis

BACKGROUND

Infectious and non-infectious risks associated with international travel can be reduced with adherence to pre-travel advice from practitioners trained in travel medicine.

METHODS

A prospective cohort study was conducted in a tertiary care children's hospital to assess adherence to malaria chemoprophylaxis, safe water and food consumption, mosquito bite protection, motor vehicle safety and travel vaccines using structured questionnaires. High risk groups assessed included child travelers and those visiting friends and relatives (VFRs).

RESULTS

In total, 290 participants (133 children and 157 adults) were enrolled and completed at least one study questionnaire. In general, with the exception of vaccines, adherence to recommendations was sub-optimal. Among children and adults, adherence to malaria prophylaxis recommendations was lower in VFRs than in non-VFRs. The proportion of children VFRs (cVFRs) and adult VFRs (aVFRs) who adhered to the following recommendations were malaria chemoprophylaxis (47%, 33%), safe water (71%, 74%) and food recommendations (18%, 6%), insect bite avoidance (21%, 12%), and motor vehicle safety (13%, 11%) respectively. Adherence to recommended vaccines uptake was greater than 90% in all groups.

CONCLUSION

With the exception of vaccine uptake, sub-optimal adherence levels to travel recommendations was identified in all groups, and in particular VFRs, highlighting the need for proactive discussions around barriers to adherence.

Association Between Recent Overnight Travel and Risk of Malaria: A Prospective Cohort Study at 3 Sites in Uganda

Background

Human movement can undermine malaria control efforts. However, understanding of the association between travel and malaria infection in Africa is limited. We evaluated the association between recent overnight travel and malaria incidence in Uganda.

Methods

All children aged 0.5-10 years and 1 adult living in 266 randomly selected households within 3 different regions of Uganda were followed up prospectively. Information on overnight travel was collected in 2015-2016. Malaria, defined as fever with parasites detected by microscopy, was measured using passive surveillance.

Results

At least 1 overnight trip was reported by 64 of 275 (23.3%) participants in Walukuba, 37 of 317 (11.7%) in Nagongera, and 19 of 314 (6.1%) in Kihihi. Among individuals who traveled, the incidence of malaria was higher in the first 60 days after traveling, compared with periods without recent travel at all 3 sites (overall, 1.15 vs 0.33 episodes per person-year; incidence rate ratio, 3.53; 95% confidence interval, 1.85-6.73; P < .001). Risk factors for malaria within 60 days after overnight travel included young age (19.5% in children vs 4.9% in adults; odds ratio, 5.29; 95% confidence interval, 1.34-21.0; P = .02) and not using an insecticide-treated net during travel (18.0% for no use vs 4.1% for any use; 5.10; 1.07-24.5; P = .04).

Conclusions

Recent overnight travel was associated with a higher incidence of malaria. Individuals who travel may represent a high-risk group that could be targeted for malaria control interventions, particularly use of insecticide-treated nets.

Malaria in Pregnancy: What the Obstetric Provider in Nonendemic Areas Needs to Know

IMPORTANCE

Globally, more than 125 million women each year are at risk of malaria during pregnancy. Endemic regions carry the greatest burden; however, with globalization, providers in nonendemic regions are encountering increasing numbers of women exposed to or infected with malaria.

OBJECTIVES

The aim of this article is to provide obstetric providers in nonendemic areas with updated information on malaria infection in pregnancy focusing on pregnancy management and malaria prevention and treatment.

EVIDENCE ACQUISITION

This article is based on review of the most recent peer-reviewed articles and guidelines from the Centers for Disease Control and Prevention and the World Health Organization.

FINDINGS

Malaria infection in pregnancy causes maternal anemia, low birth weight, preterm birth, stillbirth, and miscarriages through placental malaria and severe infections. Pregnant women traveling to malaria-endemic areas should be advised against travel. If travel must occur, they should be provided with region-specific chemoprophylaxis and given methods for preventing infection. In the event that a pregnant patient has an acute malarial infection, prompt evaluation is needed to determine whether there are severe features. Medications for uncomplicated or severe malaria infection should be started as soon as the diagnosis is made.

CONCLUSIONS AND RELEVANCE

Malaria in pregnancy causes significant perinatal complications. Obstetric providers should be aware of the impact and how to prevent and treat malaria infection during pregnancy. Malaria infection should be suspected in women with concerning symptoms and recent travel to endemic areas. Providers should know the management of uncomplicated and severe malarial infection in pregnancy.

Safety of atovaquone-proguanil during pregnancy

BACKGROUND

Malaria during pregnancy increases the risk of maternal and foetal complications. There are very limited options for prophylaxis in pregnant travellers. Atovaquone-Proguanil (AP or Malarone®) is an effective and well-tolerated antimalarial medication, but is not recommended for use in pregnancy due to limited data on safety. Passively reported adverse event data may provide additional information on the safety of AP during pregnancy.

METHODS

We analysed adverse event data on pregnancy and birth outcomes following accidental exposures to AP during pregnancy, which were passively reported to GlaxoSmithKline LLC (GSK) between 13 May 1997 and 15 August 2017. Birth outcomes of interest included live birth, miscarriage, and stillbirth. Adverse outcomes of interest were defined as any of the following: small for gestational age (SGA), low birth weight (LBW, <2500 gm), congenital anomalies, and a composite 'poor live birth outcome,' including preterm birth (PTB), LBW or SGA.

RESULTS

Among 198 women who received AP during pregnancy or breastfeeding, 96.5% occurred in women taking malaria prophylaxis, and 79.8% of exposures occurred in the first trimester. Among 195 with available birth outcome data, 18.5% resulted in miscarriage and 11.8% were elective terminations. Available adverse outcomes included SGA in 3.5% (3/85), LBW in 7.0% of infants (6/86), and the composite 'poor live birth outcome' in 13.7% (14/102). Congenital anomalies were reported in 30/124 (24.2%), with no specific pattern to suggest an effect related to AP.

CONCLUSIONS

These data provide a description of outcomes in the pregnancies reported to this dataset, and it should be noted that there is likely a bias towards reporting cases resulting in poor outcomes. While there was no specific signal to suggest a teratogenic effect of AP, AP data during pregnancy were too limited to determine AP's safety with confidence. As inadvertent exposures are not infrequent, better data are needed.

Recognition and Management of Malaria

Pretravel consultation is important and effective in preventing the spread of malaria. Travelers to high-risk malaria-endemic areas should receive antimalarial advice: a combination of mosquito avoidance measures and chemoprophylaxis. Malaria prevention can be complex owing to the individual characteristics of the traveler, travel destination, duration of stay, and type of travel. Health care providers need to obtain a complete travel history on all returned travelers with clinical infectious features and with a history of travel or migration from malaria-endemic areas. Considering the diagnosis of malaria in febrile travelers with risk factors increases the likelihood of a timely diagnosis and treatment.

Attrition-Enhanced Deracemization of the Antimalaria Drug Mefloquine

Mefloquine is an important drug for prevention and treatment of malaria. It is commercially available as a racemic mixture, wherein only one enantiomer is active against malaria, while the other one causes severe psychotropic effects. By converting the drug into a compound that crystallizes as a racemizable racemic conglomerate, the deracemization of mefloquine into the desired enantiomer was achieved.

Has doxycycline, in combination with anti-malarial drugs, a role to play in intermittent preventive treatment of Plasmodium falciparum malaria infection in pregnant women in Africa?

According to the World Health Organization (WHO), Plasmodium falciparum malaria during pregnancy is responsible for deleterious consequences for the mother and her child. The administration of intermittent preventive treatment (IPTp) with sulfadoxine–pyrimethamine (SP) at each antenatal care visit as early as 13 weeks of gestation until the time of delivery is a strategy that is currently recommended by WHO for the prevention of malaria in pregnancy. However, the emergence and the spread of the resistance to SP in Africa raise the question of the short-term effectiveness of the strategy. Dihydroartemisinin–piperaquine 120 mg/960 mg once a day for 3 consecutive days administered at least three times during the pregnancy might be an option for IPTp. The combination of 200 mg of doxycycline once a day for 3 consecutive days seems to be a good option to retard the emergence and the spread of resistance to artemisinin-based combination therapy (ACT) in Africa and improve the effectiveness of ACT in term of preterm births, neonatal morbidity and mortality. Contrary to preconceived ideas, scientific and medical data suggest that the risk of congenital malformations in the fetus or of tooth staining in infants whose mothers take doxycycline and hepatotoxicity during pregnancy is very low or non-existent. Additionally, the use of doxycycline during the first and second trimesters leads to an increase in gestational age at delivery, a decrease in the number of preterm births and a reduction in neonatal morbidity and mortality due to the beneficial antimicrobial activity of doxycycline against other infections during pregnancy. Furthermore, doxycycline has anti-malarial properties and is already recommended as prophylaxis for travellers and for treatment of falciparum malaria in combination with other anti-malarial drugs.