Tropical Health Matters

Being curious about AI and ChatGPT, I asked this question: How is climate change affecting malaria transmission. This is how it responded:

Climate change is significantly affecting malaria transmission by altering the environmental conditions that influence the life cycles of both Anopheles mosquitoes (the vectors) and the Plasmodium parasites they carry. Here’s how:

1. Temperature Rise: Faster parasite development: Warmer temperatures speed up the development of Plasmodium parasites inside mosquitoes (known as the extrinsic incubation period), increasing the chances of transmission. Mosquito lifespan: While extreme heat can be lethal, moderate warming may extend the geographical and seasonal range where mosquitoes can survive and transmit malaria. Altitude shifts: Warmer temperatures allow mosquitoes to survive at higher altitudes, leading to malaria transmission in previously malaria-free highland areas (e.g., parts of East Africa and South America).
2. Changes in Rainfall and Humidity: More breeding sites: Increased rainfall can create more standing water, ideal for mosquito breeding. However, excessive rain can also wash away larvae, so the impact depends on local conditions. Humidity: High humidity levels favor mosquito survival. Dry conditions reduce their lifespan and the chance of parasite development and transmission.
3. Changing Seasons: Longer transmission seasons: In some areas, the malaria transmission season is becoming longer due to prolonged warm and wet periods. Shifting malaria zones: Some regions may experience reduced risk (due to drought or high temperatures), while others become more suitable for transmission.
4. Extreme Weather Events: Floods and droughts: Climate variability increases the frequency of floods (which can boost mosquito breeding) and droughts (which can displace populations and lead to outbreaks in refugee camps or urban areas with poor sanitation).
5. Human Migration and Land Use: Climate-driven displacement can increase malaria risk by moving non-immune populations into endemic areas or overwhelming healthcare infrastructure.

The app also provided a summary table as attached. I next asked for reference articles on the topic and eight were provided. All checked out as coming from real journals/publications. Links are provided below. Without verifiable references the information could be suspect. This may be a useful tool to begin exploration on health and tropical disease topics if care is taken to verify information obtained.

1. **Influence of Future Climate Scenarios on Malaria Transmission in India.** This study utilized the VECTRI model to estimate malaria’s Entomological Inoculation Rate (EIR) under various climate scenarios (RCP 2.6, 4.5, and 8.5) for the period 2020–2029. The findings indicated a significant decline in malaria risk across all scenarios, with a decrease in EIR ranging from 0.3 to 2.6 EIR/person/day, attributed to reduced rainfall and moderate temperature increases. ([malariajournal.biomedcentral.com][1])
2. **Impact of Climate Change on Temperature Variations and Parasite Development in Chennai, India.** Research in Chennai revealed that global warming has increased atmospheric temperatures, leading to a decrease in the extrinsic incubation period (EIP) of *Plasmodium* parasites. Shorter EIP means faster parasite development, potentially enhancing transmission rates. However, extreme temperatures may still pose a risk to parasite development. [parasitesandvectors.biomedcentral.com][2])
3. **Predicting Malaria Risk Considering Vector Control Interventions Under Climate Change Scenarios.** This study modeled malaria risk in Uganda by integrating environmental variables (rainfall, humidity, temperature, vegetation) and vector control interventions (indoor residual spraying and long-lasting insecticidal nets). The results projected a 25% to 30% increase in annual malaria cases by the 2050s in the absence of interventions, underscoring the importance of maintaining control measures in the face of climate change. ([pmc.ncbi.nlm.nih.gov][3])
4. **Projected Impacts of Climate Change on Environmental Suitability for Malaria Transmission in West Africa.** This research assessed how climate change affects the environmental suitability for malaria transmission in West Africa. The findings suggest that increased rainfall and temperature could expand mosquito habitats, thereby increasing malaria transmission potential in certain regions. ([ehp.niehs.nih.gov][4])
5. **Climate Change Could Shift Disease Burden from Malaria to Arboviruses in Africa.** This study discusses how rising temperatures may reduce the suitability for malaria transmission while enhancing conditions for arboviruses like dengue and chikungunya. Such shifts could lead to a re-emergence of diseases in regions previously affected by malaria. ([pmc.ncbi.nlm.nih.gov][5])
6. **How climate change will affect malaria transmission | ScienceDaily**
7. **Malaria Transmission in Africa Shifts with the Climate—and Hydrology.** This article highlights how climate-induced changes in hydrology, such as altered river flows and evaporation rates, can impact malaria transmission patterns in Africa. The study emphasizes the need to consider hydrological factors in predicting and managing malaria risks. ([sciencedaily.com][6], [eos.org][7])
8. **Mapping Current and Future Thermal Limits to Suitability for Malaria Transmission by the Invasive Mosquito *Anopheles stephensi.*** This research mapped the thermal limits for malaria transmission by *Anopheles stephensi*, an invasive mosquito species. The findings indicate that climate change could expand the transmission season for *Plasmodium falciparum* in northern latitudes, including parts of North America and Europe. ([ncbi.nlm.nih.gov][8])

Lance Rombro shared his concerns about dengue fever in our discussion forum for the course Urban Health in Developing Countries. He was addressing urban equity issues wherein slum dwellers are disproportionately affected.

Although I have not experienced this urban health equity problem personally, in the past, I closely interrogated and proposed interventions to target the increased rates of dengue transmission in the Heliópolis favela of São Paulo, Brazil. In 2024, Brazil had the most dengue cases (3, 040,736 laboratory confirmed cases and 6,296,795 suspected cases) of any country in the world. Moreover, São Paulo is the sixth most populated city in the world, and the high population density has led to an increased likelihood of infected individuals and a higher prevalence of dengue. Within São Paulo, the highest prevalences of dengue are found in favelas (similar to slums), which are communities with lower socioeconomic status that have worse infrastructure and resilience to combat dengue transmission.

In Heliópolis, it is common for homeowners to have tires, flower pots, and basins lying near the home, which create an ideal breeding ground for the Aedes aegypti mosquito, which is the vector for dengue fever. A. aegypti prefer to breed in still, clean water, which can accumulate in many sources (i.e., water barrels) throughout Heliópolis.

Combatting this issue requires several intervention streams focusing on different aspects, from education to product access and epidemiology. For example, educating the community could involve handing out dengue info-pamphlets at farmers markers or hoisting banners at soccer games, two environments that are heavily frequented by community members. Product access interventions could manifest as town hall events where supplies like mosquito repellent or bed nets are widely distributed to the community. There could also be a focus on insecticide spraying in homes (although this may cause hesitancy in the community) and repair of leaky water barrels that can promote the likelihood of mosquito breeding.

Finally, tracking and recording epidemiological statistics on dengue prevalence and incidence could inform both public health professionals and the community about the current risk of dengue and inform the need for future interventions to further limit dengue exposure and transmission.

The issue of dengue in Heliópolis presents itself in many ways. Community buy-in can realize tangible interventions that could help reduce the risk of dengue in the favela. In many ways, this form of primary prevention is necessary, given that later forms of prevention and treatment may be financially infeasible for members of the favela who have limited economic resources. However, achieving effective strategies also requires stakeholder engagement with community members, government entities (such as the Ministry of Health), and SINAN (the main system for collecting dengue statistics in São Paulo).

Ultimately, with most urban equity concerns, the main ethical issues involve failures to uphold justice and beneficence. However, focusing on this specific population would be an essential opportunity to support, uplift, and build the resilience of a community that consistently faces social and economic marginalization. It is also worth noting that Heliópolis faces a risk from other mosquito-borne diseases like Zika virus, so proposed solutions and interventions could cover a broad spectrum of public health concerns.

The World Health Organization has prepared an important document entitled “Health is the Argument for Climate Action: COP29Health is the Argument for Climate Action: COP29 Special Report on Climate Change and Health”. Malaria and other vector borne diseases are highlighted.

The report addresses diseases carried by mosquitoes by stating that, “Climate change increases the transmission of deadly infectious diseases such as dengue, malaria, West Nile virus” and others which are temperature and rainfall dependent. In particular, malaria transmission is intricately connected with temperature and rainfall patterns, and extreme weather events have been shown to cause rapid spikes in cases.”

Climate change not only effects environmentsClimate change not only effects environments where these diseases thrive, but impacts the livelihoods of populations, reducing their ability to pay for prevention and treatment. Migration and displacement also may result increasing vulnerability to disease.

Two of the report’s recommendations have special bearing on malaria. One is the need to “develop and implement innovative financing mechanisms, such as a global health insurance scheme for climate-vulnerable nations” and communities. A second is the importance of “Strengthen(ing) health surveillance systems, particularly in low-income countries, to better track and respond to climate-related health impacts.”

Recognizing the climate dependence of malaria will be a crucial step in eliminating the disease.

The 2024 World Malaria Day Theme of “Gender, Health Equity, and Human Rights” cannot be divorced from the inequities of climate change wherein the countries that contribute the least to the problem suffer the most, including the deleterious effects of changing malaria geographics. The current severe drought in Zambia, Zimbabwe, and Malawi is a case in point.

As a recent headline in VOA news states, “UN officials in Zambia to assess worst drought in 20 years.” The government has declared a drought officially where it “has affected a total of 8 provinces across the country with highest impacts in Southern, Central, Eastern, North-western, Western, and Lusaka Provinces.”

Drought should not be confused with a “normal” dry season. What we are seeing in Southern Africa now is an extended dry period in what should have been the rainy season. A study in Mali suggests that adult malaria-carrying mosquitoes “have endured the dry season by aestivating—the hot-weather equivalent of hibernating.” Unfortunately, an extended dry period of a drought may be more difficult to endure for the adults, but possibly the eggs are more resistant. Additional studies paint a more complicated picture.

Weather cycles intensify with climate change. El Niño, which can lead to droughts also produces warming in higher elevations so there tends to be an increase in malaria transmission in areas in the highlands.

Research in Zambia published just two years ago reported increasing trends of malaria in areas covering over 47% of all health facilities, while a declining trend was seen in areas covering 27% of health facilities. The decreasing trend was noticeable in the south, where malaria risk is lowest, and current drought conditions higher. The authors stress the need for continued geographic surveillance and implementation of control strategies geared to the conditions in each area.

A systematic review of the effects of climate change identified “vector borne disease (including malaria, dengue and West Nile Virus)” as a major concern as well as “nutrition-related effects (including general malnutrition and mortality, micronutrient malnutrition, and anti-nutrient consumption),” which compromises the ability of children to fight disease. The review found different impacts of drought ranging from increase mortality a year after a drought, to the disappearance of some vector species. The lesson is that each country needs to monitor their situation carefully. For Zambia, UNICEF reports that, “significant number are children, at risk of food insecurity, acute malnutrition, and disease.”

Research on drought effects on malaria arose from a study that examined the effects of drought on malaria infection (genetic) complexity and transmission in lizards (Plasmodium mexicanum and Sceloporus occidentalis). The authors noted that, “relationship between rainfall and parasite prevalence is somewhat more ambiguous.” Thus, the authors recommended that more information is needed about human malaria parasites and drought since “drought may cause shifts in human disease outcomes independent of any changes to prevalence.”

The United Nations challenges us by observing that, “Due to the complex relationship between malaria and climate change, gaps in knowledge still exist in the mechanisms of the linkage.” Changes in temperature, rainfall, and humidity need to be monitored for effects on vectors, parasites, and human movement. The current situation requires a more nuanced and complex approach to interventions if malaria elimination can be achieved while also preventing gender discrimination, promoting health equity and preserving human rights.

A new study from Kenya addresses one of the major challenges to malaria elimination. The authors note changing vector behaviour towards early morning biting has been established. Children are observed to come to school early, as do mosquitoes that have “peak landing between 06:00 and 07:00.” They also found that mosquitoes continue their activity until 11:00. The An. funestus mosquitoes they collected “were either fed or gravid, potentially indicative of multiple bloodmeals within each gonotrophic cycle, and had a sporozoite rate of 2.05%.” this is of particular concern because school aged children are not always prioritized in various malaria control interventions.

In Cambodia researchers found that “20% of collected Anopheles were active during the day, with increased day biting during the dry season.” Ellie Sherrard-Smith and colleagues explain that bednets and indoor residual spray are intended to work best when people are indoors and sleeping. They caution that, “Mosquito bites taken outside of these times contribute to residual transmission which determines the maximum effectiveness of current malaria prevention.” Their review documented that on average 21% of mosquito bites in Africa take place outside bedtime.

A study in Tanzania by Nicodem J Govella et al. noted that the use of insecticide-treated nets for malaria control has been associated with shifts in mosquito vector feeding behaviour including earlier and outdoor biting on humans. They concluded that efforts highlighting the need for control methods that target early and outdoor biting mosquitoes are now required.

In short, various changing factors ranging from climate and mosquito genetics to even the existing interventions like bednets that we use to control the biting of malaria carrying mosquitoes, threaten our ability to eliminate malaria. New vector control measures are urgently needed as is expansion of other interventions like malaria vaccines.

On Earth Day (and hopefully throughout the year) we contemplate what humans have done to ecosystems and climate. Should mosquitoes actually think about us at all, they might be grateful for the changes that increase their breeding sites.

Deforestation and modern agricultural practices favor the Anopheles group. Expanding urbanization makes life easier for the Aedes family.

Overall warming may open up new parts of the world for mosquitoes, though hotter and drier areas left behind make mosquito propagation more difficult. These highly mobile creatures may have few complaints for now, though proposed efforts to disperse particles in the atmosphere for cooling effect and current efforts to release sterile male mosquitoes into the environment might worry people as well as mosquitoes.

Human activity has modified the environment, and mosquitoes have taken advantage where they can. Environmental efforts to beat back mosquitoes need to be thought through very carefully to avoid more unintended consequences.

Save the Children addresses various ways to protect children and families from malaria. Here we learn about Mosquito net knowledge, ownership, use, acceptability and preferences among primary caregivers of children under 5 years of age, pregnant women and household heads in Cote d’Ivoire. This information is being presented at the 2021 American Society of Tropical Medicine and Hygiene Annual Meeting. See Author List below.

Strengthening vector control measures among populations at higher risk of malaria, such as pregnant women and children under 5 years of age (U5s), is crucial to malaria control. Cote d’Ivoire has set itself a number of targets for malaria control by 2025. These include: at least 90% of the population are aware of national malaria prevention measures and at least 80% of the general population, pregnant women and children U5 sleep under an LLIN. One of the specific aims of this study was to assess mosquito net knowledge, ownership, use, acceptability and preferences of primary caregivers of children U5, pregnant women and household heads.

A mixed-methods study was conducted in rural and urban areas in 20 health districts of Cote d’Ivoire. A total of 1,812 households composed of 8,813 members were surveyed using a structured questionnaire. Only households who had one or more children under five years of age and/or a pregnant woman were included in the study. Qualitative data were gathered through twenty focus group discussions. Data triangulation of the qualitative and quantitative data was used during analysis.

Sixty percent of participants cited mosquito nets as the main malaria preventive measure. The majority of participants (95.6%) received information on the use of mosquito nets and over half of them received it from mass distribution campaign agents (51.1%). Although 79.5% of households owned at least one mosquito net, less than half (46.47%) owned one mosquito net for two people. The majority (98.2%) of participants received a free mosquito net. Nets were reportedly received mainly through mass distribution campaigns (54.99%) and ANC visits (39.0%). Self-reported mosquito net use by the head of households was 53.5%. This was higher for pregnant women and children U5, 76.2% and 83.2% respectively. However, only 53.0% of mosquito nets were suspended over a bed. Reasons for not using a mosquito nets were feeling of suffocation, heat, side effects, and poor condition of the mosquito net.

While mosquito net was reported as the main malaria preventive measure, mosquito net coverage and use remains below national targets. In addition, there was a noted gap between coverage and net use, potentially undermining the effectiveness of net-related interventions that could impact malaria control efforts in Cote d’Ivoire. The design, material, and condition of nets are important factors for user preferences that appear to drive net use.

AUTHOR LIST:

Edouard C. Balogoun1, Manasse N. Kassi1, Philomène A. Beda1, Serge B. Assi2, Jacob Y. Agniman1, Florence Kadjo-Kouadio3, Michel N’da-Ezoa4, Aristide E. Kouadio1, Joel Koffi1, Apollinaire N. Kouadio1, Paul Bouey5, Sara Canavati5, Eric Swedberg5 — 1Save the Children, Abidjan, Côte D’Ivoire, 2Le Programme Nationale de Lutte contre le Paludisme (PNLP), Abidjan, Côte D’Ivoire, 3Médecin spécialiste de Santé, Abidjan, Côte D’Ivoire, 4Socio-Anthropologue de la Santé, Abidjan, Côte D’Ivoire, 5Save the Children, Washington, DC, United States

The search for adjunctive therapy to aid in recovery from cerebral malaria is explored in Malaria Journal. A faster acting crystalline form of an insecticide is studied. In Nigeria the National Malaria Elimination Program advocates for equal footing with COVID-19 action. Links to full stories and abstracts are found below.

Dimethyl fumarate reduces TNF and Plasmodium falciparum induced brain endothelium activation in vitro

Neida K. Mita-Mendoza, and colleagues studied Cerebral malaria (CM) which is associated with morbidity and mortality despite the use of potent anti-malarial agents. Brain endothelial cell activation and dysfunction from oxidative and inflammatory host responses and products released by Plasmodium falciparum-infected erythrocytes (IE), are likely the major contributors to the encephalopathy, seizures, and brain swelling that are associated with CM. The development of adjunctive therapy to reduce the pathological consequences of host response pathways could improve outcomes.

To accurately reflect clinically relevant parasite biology a unique panel of parasite isolates derived from patients with stringently defined CM was developed. The effect of TNF and these parasite lines on primary human brain microvascular endothelial cell (HBMVEC) activation in an in vitro co-culture model was tested. HBMVEC activation was measured by cellular release of IL6 and nuclear translocation of NF?B. The transcriptional and functional effects of dimethyl fumarate (DMF), an FDA approved drug which induces the NRF2 pathway, on host and parasite induced HBMVEC activation was characterized. In addition, the effect of DMF on parasite binding to TNF stimulated HBMVEC in a semi-static binding assay was examined.

The findings provide evidence that targeting the nuclear factor E2-related factor 2 ( NRF2) pathway in tumour necrosis factor (TNF) and parasite activated human brain microvascular endothelial cell (HBMVEC) mediates multiple protective pathways and may represent a novel adjunctive therapy to improve infection outcomes in CM.

Fast-acting insecticide polymorph could boost malaria-control efforts

Chemistry World reports on a faster-acting version of a common insecticide could boost malaria control efforts. The new crystalline form of deltamethrin is absorbed by mosquitoes 12 times faster than commercial forms and could help to limit malaria transmission despite growing rates of insecticide resistance.

Microcystals of contact insecticides like deltamethrin are crucial ingredients in indoor sprays and treated bed nets used to combat malaria-spreading mosquitoes. But many mosquito populations are developing resistance to these compounds, which is harming efforts to control the disease.

Treat Malaria as National Health Emergency, NEMP tells Federal Government

The Coordinator of National Malaria Elimination Programme (NEMP), has asked the federal government to tackle malaria as a national health emergency in the same manner COVID-19 pandemic is being handled. Against the background of increasing poverty in the country, Civil Society in Malaria Control, Immunisation and Nutrition (ACOMIN) has said there is a direct linkage between malaria scourge and the level of poverty in communities.

Speaking at a meeting with the civil society group involved in anti malaria advocacy, Coordinator of NEMP, said the current level of funding of the health sector by government is unacceptably low.

The American Journal of Tropical Medicine and Hygiene has several new articles on malaria. Abstracts are shared. Two articles examine the role of travel in malaria transmission, both cross-border and rural-urban. Another considers the effect on pharmacokinetics of lumefantrine due to gut bacteria. In Uganda indoor spraying has reduced transmission, but asymptomatic cases remain among children. The challenges of asymptomatic malaria to elimination efforts is also examined in India. Links to the articles are found below.

Evidence of Microbiome–Drug Interaction between the Antimalarial Lumefantrine and Gut Microbiota in Mice

The antimalarial drug lumefantrine exhibits erratic pharmacokinetics. Intersubject variability might be attributed, in part, to differences in gut microbiome–mediated drug metabolism. We assessed lumefantrine disposition in healthy mice stratified by enterotype to explore associations between the gut microbiota and lumefantrine pharmacokinetics. Gut microbiota enterotypes were classified according to abundance and diversity indices from 16S rRNA sequencing. Pharmacokinetic parameters were computed using noncompartmental analysis. Two distinct enterotypes were identified.

Maximal concentration (C max) and total drug exposure measured as the area under the drug concentration–time curve (AUC0–24) differed significantly between the groups. The mean and standard deviation of C max were 660 ± 220 ng/mL versus 390 ± 59 ng/mL (P = 0.02), and AUC0–24 was 9,600 ± 2,800 versus 5,800 ± 810 ng × h/mL (P = 0.01). In healthy mice intragastrically dosed with the antimalarial drug lumefantrine in combination with artemether, lumefantrine exposure was associated with gut bacterial community structure. Studies of xenobiotic–microbiota interactions can inform drug posology and elucidate mechanisms of drug disposition.

Malaria Transmission, Infection, and Disease following Sustained Indoor Residual Spraying of Insecticide in Tororo, Uganda

Tororo, a district in Uganda with historically high malaria transmission intensity, has recently scaled up control interventions, including universal long-lasting insecticidal net distribution in 2013 and 2017, and sustained indoor residual spraying (IRS) of insecticide since December 2014. We describe the burden of malaria in Tororo 5 years following the initiation of IRS. We followed a cohort of 531 participants from 80 randomly selected households in Nagongera subcounty, Tororo district, from October 2017 to October 2019. Mosquitoes were collected every 2 weeks using CDC light traps in all rooms where participants slept, symptomatic malaria was identified by passive surveillance, and microscopic and submicroscopic parasitemia were measured every 4 weeks using active surveillance. Over the 2 years of follow-up, 15,780 female anopheline mosquitos were collected, the majority (98.0%) of which were Anopheles arabiensis.

The daily human biting rate was 2.07, and the annual entomological inoculation rate was 0.43 infective bites/person/year. Only 38 episodes of malaria were diagnosed (incidence 0.04 episodes/person/year), and there were no cases of severe malaria or malarial deaths. The prevalence of microscopic parasitemia was 1.9%, and the combined prevalence of microscopic and submicroscopic parasitemia was 10.4%, each highest in children aged 5–15 years (3.3% and 14.0%, respectively). After 5 years of intensive vector control measures in Tororo, the burden of malaria was reduced to very low transmission levels. However, a significant proportion of the population remained parasitemic, primarily school-aged children with submicroscopic parasitemia, providing a potential reservoir for malaria transmission.

Malaria Diagnosed in an Urban Setting Strongly Associated with Recent Overnight Travel: A Case–Control Study from Kampala, Uganda

Malaria is frequently diagnosed in urban Kampala, despite low transmission intensity. To evaluate the association between recent travel out of Kampala and malaria, we conducted a matched case–control study. Cases were febrile outpatients with a positive malaria test; controls were febrile outpatients with a negative test. For every two cases, five controls were selected, matching on age. Data were collected on recent overnight travel out of Kampala (past 60 days), destination and duration of travel, and behavioral factors, including sleeping under an insecticide-treated net (ITN) during travel. From July to August 2019, 162 cases and 405 controls were enrolled. The locations of residence of cases and controls were similar. More controls were female (62.7% versus 46.3%, P < 0.001). Overall, 158 (27.9%) participants reported recent overnight travel.

Travelers were far more likely to be diagnosed with malaria than those who did not travel (80.4% versus 8.6%, OR 58.9, 95% CI: 23.1–150.1, P < 0.001). Among travelers, traveling to a district not receiving indoor residual spraying of insecticide (OR 35.0, 95% CI: 4.80–254.9, P < 0.001), no ITN use (OR 30.1, 95% CI: 6.37–142.7, P < 0.001), engaging in outdoor activities (OR 22.0, 95% CI: 3.42–141.8, P = 0.001), and age < 16 years (OR 8.36, 95% CI: 2.22–56.2, P = 0.03) were associated with increased odds of malaria. Kampala residents who traveled overnight out of the city were at substantially higher risk of malaria than those who did not travel. For these travelers, personal protection measures, including sleeping under an ITN when traveling, should be advocated.

Prevalence of Asymptomatic Malaria Parasitemia in Odisha, India: A Challenge to Malaria Elimination

The prevalence of malaria in India is decreasing, but it remains a major concern for public health administration. The role of submicroscopic malaria and asymptomatic malaria parasitemia and their persistence is being explored. A cross-sectional survey was conducted in the Kandhamal district of Odisha (India) during May–June 2017. Blood samples were collected from 1897 individuals for screening of asymptomatic parasitemia. Samples were screened using rapid diagnostic tests (RDTs) and examined microscopically for Plasmodium species. Approximately 30% of randomly selected samples (n = 586) were analyzed using real-time PCR (qPCR), and the genetic diversity of Plasmodium falciparum was analyzed.

The prevalence of Plasmodium species among asymptomatic individuals detected using qPCR was 18%, which was significantly higher than that detected by microscopy examination (5.5%) or RDT (7.3%). Of these, 37% had submicroscopic malaria. The species-specific prevalence among asymptomatic malaria-positive cases for P. falciparum, Plasmodium vivax, and mixed infection (P. falciparum and P. vivax) by qPCR was 57%, 29%, and 14%, respectively. The multiplicity of infection was 1.6 and 1.2 for the merozoite surface protein-1 gene (msp1) and (msp2), respectively. Expected heterozygosity was 0.64 and 0.47 for msp1 and msp2, respectively. A significant proportion of the study population, 105/586 (18%), was found to be a reservoir for malaria infection, and identification of this group will help in the development of elimination strategies.

Travel Is a Key Risk Factor for Malaria Transmission in Pre-Elimination Settings in Sub-Saharan Africa: A Review of the Literature and Meta-Analysis

By sustaining transmission or causing malaria outbreaks, imported malaria undermines malaria elimination efforts. Few studies have examined the impact of travel on malaria epidemiology. We conducted a literature review and meta-analysis of studies investigating travel as a risk factor for malaria infection in sub-Saharan Africa using PubMed. We identified 22 studies and calculated a random-effects meta-analysis pooled odds ratio (OR) of 3.77 (95% CI: 2.49–5.70), indicating that travel is a significant risk factor for malaria infection.

Odds ratios were particularly high in urban locations when travel was to rural areas, to more endemic/high transmission areas, and in young children. Although there was substantial heterogeneity in the magnitude of association across the studies, the pooled estimate and directional consistency support travel as an important risk factor for malaria infection.

News and abstracts provide more on the surge of malaria in Mali. COVID-19 complicates malaria elimination in Southeast Asia. Peace Corps health care for volunteers in Comoros is questioned. Malaria risk in Ecuador is investigated. Risk maps are used/not used in three Sub-Saharan countries. The potential of microbiological control is considered. More information on each topic is available in the links provided.

Health workers raise alarm over surge in malaria cases, deaths in Mali

More details emerge on malaria in northern Mali. Medical workers in Mali raised an alarm over a surge in malaria cases which has seen at least 23 people killed by the disease in just the past one week. About 13,000 malaria cases were reported in the north by medical workers between September 21 and 27, representing an 88 percent increase in cases from the previous week. 59 people have died of malaria in the nation’s northern region since the beginning of the year, according to the ministry, which confirmed the deaths of the 23 people over the aforementioned September period.

Will COVID-19 hamper ASEAN’s fight to eliminate malaria?

Although progress elsewhere in the world has been slow, in the Asia-Pacific, deaths due to the mosquito-borne disease have dropped by 70% and cases have dropped by 22%. Within ASEAN, those figures—according to the Asia Pacific Leaders Malaria Alliance (APLMA)—are 92% and 67% respectively. The battle to eliminate malaria is continually evolving with different species of disease-carrying mosquitoes and parasites presenting new challenges. In 2008, a new strain of malaria that proved resistant to the anti-malarial drug artemisinin, nicknamed “super malaria”, emerged in Cambodia. It spread through the Greater Mekong region into Laos, Thailand and Vietnam and by 2017, it had developed resistance to another drug, piperaquine.

In response, scientists and researchers focused their resources on areas where the new strain was present and were making headway towards eliminating it. COVID-19 could threaten that progress. “We have enough evidence from the Ebola epidemic to suggest how progress on malaria elimination could be derailed and we are seeing some clear warnings now,” APLMA/APMEN commented. Historically, malaria cases have risen in countries where healthcare is interrupted due to conflict, disaster and war.

Peace Corps faces questions over death of volunteer from Inverness

By Sheryl Gay Stolberg of the New York Times reported that the Peace Corps, which suspended all operations for the first time in its history as the novel coronavirus raced around the globe, is facing renewed questions about the quality of its medical care — in particular, after the death of a 24-year-old volunteer from undiagnosed malaria — as it prepares to send volunteers back into the field.

An investigation by the Peace Corps inspector general documented a string of problems with Heiderman’s care. Her doctor had “limited training in tropical medicine,” the investigation found, and failed to test for malaria, which would have revealed that Heiderman had been infected by the deadliest malaria parasite. The Peace Corps was also using outdated 2006 guidelines for malaria, which did not reflect the current standard of care.

Anopheline and human drivers of malaria risk in northern coastal Ecuador

Understanding local anopheline vector species and their bionomic traits, as well as related human factors, can help combat gaps in protection. In San José de Chamanga, Esmeraldas, at the Ecuadorian Pacific coast, anopheline mosquitoes were sampled by both human landing collections (HLCs) and indoor-resting aspirations (IAs) and identified using both morphological and molecular methods.

Among 222 anopheline specimens captured, based on molecular analysis. The exophagic feeding of anopheline vectors in San Jose de Chamanga, when analysed in conjunction with human behaviour, indicates a clear gap in protection even with high LLIN coverage. The lack of indoor-resting anophelines suggests that indoor residual spraying (IRS) may have limited effect. The presence of asymptomatic infections implies the presence of a human reservoir that may maintain transmission.

How useful are malaria risk maps at the country level?

This study examined the perceptions of decision-makers in Kenya, Malawi and the Democratic Republic of Congo. Declining malaria prevalence and pressure on external funding have increased the need for efficiency in malaria control in sub-Saharan Africa (SSA). Modelled Plasmodium falciparum parasite rate (PfPR) maps are increasingly becoming available and provide information on the epidemiological situation of countries. However, how these maps are understood or used for national malaria planning is rarely explored. In this study, the practices and perceptions of national decision-makers on the utility of malaria risk maps, showing prevalence of parasitaemia or incidence of illness, was investigated.

Three different types of maps were used to show malaria epidemiological strata: malaria prevalence using a PfPR modelled map (Kenya); malaria incidence using routine health system data (Malawi); and malaria prevalence using data from the most recent Demographic and Health Survey (DRC). In Kenya the map was used to target preventative interventions, including long-lasting insecticide-treated nets (LLINs) and intermittent preventive treatment in pregnancy (IPTp), whilst in Malawi and DRC the maps were used to target in-door residual spraying (IRS) and LLINs distributions in schools. Maps were also used for operational planning, supply quantification, financial justification and advocacy. Findings from the interviews suggested that decision-makers lacked trust in the modelled PfPR maps when based on only a few empirical data points (Malawi and DRC). Despite the availability of national level modelled PfPR maps in all three countries, they were only used in one country.

Infection of highly insecticide-resistant malaria vector Anopheles coluzzii with entomopathogenic bacteria

This study found that Chromobacterium violaceum reduces its survival, blood feeding propensity and fecundity of mosquitoes in Burkina Faso. The study was motivated by the concern that malaria eradication will not be achieved without the introduction of novel control tools. Microbiological control might be able to make a greater contribution to vector control in the future. The interactions between bacteria and mosquito make mosquito microbiota really promising from a disease control perspective.
Methods

To assess entomopathogenic effects of C. violaceum infection on mosquitoes, three different types of bioassays were performed in laboratory. These bioassays aimed to evaluate the impact of C. violaceum infection on mosquito survival, blood feeding and fecundity, respectively. During bioassays mosquitoes were infected through the well-established system of cotton ball soaked with 6% glucose containing C. violaceum.

The data showed important properties of Burkina Faso C. violaceum strains, which are highly virulent against insecticide-resistant An. coluzzii, and reduce both mosquito blood feeding and fecundity propensities. However, additional studies as the sequencing of C. violaceum genome and the potential toxins secreted will provide useful information render it a potential candidate for the biological control strategies of malaria and other disease vectors.