Tropical Health Matters

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.

Professor Jane Carlton, PhD, Director of Johns Hopkins Malaria Research Institute was introduced by Dean Ellen MacKenzie to give a Dean’s Lecture entitled “Malaria: History, current status, and the promise of ‘omics and AI.”

Prof. Carlton first gave an overview of JHMRI, which was founded in 2001. She stepped into director role in 2023. She started with the encouraging premise that AI and ‘omics can supercharge our research and pointed out the power of comparative genomics on understanding parasites and disease. Her goal is to translate discovery into real world impact through collaborations.

The talk started with a brief malaria history. Malaria was described as an ancient disease and remains one of top infectious diseases worldwide. There were 2.63 million cases and more than half a million deaths in 83 endemic countries in 2023. Today 44 countries are malaria-free.

Up until now, Prof. Carlton noted, the malaria map has been shrinking. There was a precipitous decline in malaria in India from 23 million cases to 2 million. The disease is a true humanitarian issue with a large impact on people living in resource-limited settings where housing is basic and offers no protection from mosquitoes.

The JHMRI is supported by Bloomberg philanthropies, and from that base faculty research examines, among others, better methods for controlling mosquitoes (see slide), new diagnostic tests and therapeutics, and the next generation of vaccines. Key assets to support research include mosquito insectaries and a malaria parasite core. The insectaries produce 60,000 mosquitoes per week, and with these it is possible to complete the life cycle in the laboratory.

Continuing education is another important function of JHMRI which has three conferences per year including the upcoming World Malaria Day 2025 symposium. One can also learn from the Malaria Minute podcast. The upcoming “Vector Encounter” provides sharing and learning for researchers.

JHMRI studies malaria at field sites in Africa and Asia where country collaborators are partners. Emphasis is on local capacity building in countries like Zambia, Ethiopia, Kenya, and Uganda. Researchers and the national malaria control programs in these countries work hand-in-hand.

JHMRI is involved in developing the next generation of vaccines. One approach if a human monoclonal antibody that prevents malaria infections. Another develops a vaccine that transcends’ malaria parasite strains with structure guided mimicry of an essential P. falciparum receptor-ligand complex enhances cross neutralizing antibodies. A third example asks “How many parasites does it take to cause malaria?” and assesses infection likelihood through mosquito parasite burden.

To understand the theme of her talk, Prof. Carlton reviewed the promise of ‘omics and AI in the context of her work at a center of excellence in India. Pioneering work using Malaria camps in hard-to-reach villages in Odisha, India. The main activities mobilized villagers to gather for mass screening, treatment, education, and intensified vector control. From there, Indoor Residual Spraying was planned and insecticide treated bednets were distributed. Other maternal and child health activities were incorporated. After three rounds/visits in the remote villages a great drop of malaria cases was seen. WHO lauded the camps.

In addition to lessons about the importance of surveillance, mixed strategies, and community mobilization for controlling malaria, the team learned about the growing challenge of reduced effectiveness of Rapid Diagnostic Tests. The problem arose because tests were dependent on a protein that was no longer being expressed due to Pfhrp2 gene deletions, leading to false negative test results. The team was encouraged to identify more proteins to find a more stable and central one to use in testing. Through machine learning, this work is ongoing but promising.

While we are on the verge of several research and programmatic breakthroughs, Prof. Carlton reminded the audience that we are in calamitous times. She recalled that the United States has been the top donor government to malaria efforts through Presidents Malaria Initiative and Global Fund to Fight AIDS, Tuberculosis, and Malaria. PMI was founded in 2005, and has contributed to a decline in malaria death rates of close to 50%.

With suspension of funding, an estimated increase of 12.5-17.9 million malaria cases and 71,000-166,000 malaria deaths are expected this year. Already there are serious impacts on the supply chain for major malaria commodities as estimated by the Roll Back Malaria Partnership as seen on their RBM dashboard and supply chain gap estimates where six endemic countries have less than a 3-month supply of RDTs and eleven have less than a 6-month supply.

Prof Carlton ended by saying, “I think the hope is in science, right? The hope is in research. There are definitely new initiatives, new tools which are coming to the forefront, some of which I mentioned, and several of which we’re developing here at the malaria Research Institute. I do know the World Health Organization has got together with other countries to provide additional funding and support for those countries who have lost support through PMI.”

As part of the work for the Johns Hopkins University course on Social and Behavioral Foundations of Primary Health Care, Bea Manjon posted in the class blog about the threat of hypertension to people and the health system in the Philippines as seen below.

by smanjon

As part of the work for the Johns Hopkins University course on Social and Behavioral Foundations of Primary Health Care, Skylar Chapdelaine posted in the class blog about HIV/AIDS Treatment in South Africa.

South Africa has the highest global burden of HIV with over 7.7 million people living with the virus. While over 5 million people are on antiretroviral therapy (ART), the decline of international funding especially from the U.S. President’s Emergency Plan for AIDS Relief challenges the sustainability of this.

For years the United States has played an important role in financing South Africa’s HIV response; however, as this money is expected to be lost, South Africa must seek alternative funding mechanisms to sustain programming.

Initiatives and Challenges

Despite financial uncertainties, South Africa has announced a goal of putting an additional 1.1 million people on treatment by the end of 2025 as a step towards their ending AIDS as a threat by 2030.

However, challenges persist. The loss of funding has already affected healthcare personnel, drug supply chains, and monitoring systems. Community organizations such as the Treatment Action Campaign (TAC) have previously been instrumental in expanding ART access, but the financial constraints are limiting their availability to help advocate for patients.

Additionally, international pharmaceutical companies dominate the ART market. Intellectual property restrictions limit local production making ART expensive and difficult to scale up. Without affordable alternatives, millions with HIV could face interruptions in treatment.

Strategies for Engaging Stakeholders

To influence policymakers to secure a sustainable future for HIV treatment, stakeholders need to be strategically engaged.

One of the most crucial stakeholders in this, the South African National AIDS Council (SANAC), plays an important role in coordinating the national HIV response through uniting multiple sectors. SANAC can lead by organizing regular policy roundtables and cross sector forums that bring government officials, civil society leaders, and private sector representatives together. By facilitating these conversations, SANAC can guide the development of policy briefs that offer evidence based solutions, such as strategies to boost local ART production and sustainable financing models and engage policymakers.

Without urgent action from policymakers to begin securing sustainable funding, millions of South Africans are at risk of disruptions in their treatment.

As part of the work for the Johns Hopkins University course on Social and Behavioral Foundations of Primary Health Care, Simon Riek posted in the class blog about a community-based health initiative in South Sudan as seen below.

South Sudan continues to experience high maternal and child mortality rates, limited healthcare access, and a shortage of trained professionals. The Boma Health Initiative (BHI) is a community-based healthcare program that trains and deploys Community Health Workers (CHWs) to deliver maternal care, immunizations, and disease management in underserved areas. While promising, BHI faces funding instability, supply shortages, and a lack of standardized training and supervision. To ensure sustainable impact, I strongly advocate for increased financial investment in CHW’s training as a priority policy goal.

For this policy to succeed, we must engage key stakeholders strategically. World Health Organization (WHO) – Department of Health Systems Governance & Financing. WHO supports community-based health models and can provide technical and financial resources. Advocacy Approach: Partner with WHO to champion CHW training through reports, policy dialogues, and media engagement.

South Sudan’s Ministry of Health (MoH) – Directorate of Community Health Services. As the lead health agency, MoH oversees BHI implementation and CHW workforce management. The advocacy approach should push for MoH to allocate domestic funding for CHW training, ensuring sustainability beyond donor reliance.

The World Bank’s Human Development Practice Group funds health initiatives but has not directly committed to BHI. Advocacy approaches include presenting cost-effectiveness evidence to secure investment in CHW training programs.

Some physicians from the South Sudan Doctor’s Association (SSDA) fear CHWs will replace trained professionals, while others support task-sharing. Advocacy approaches include collaborating with SSDA to define CHW roles, ensuring they complement rather than replace professional healthcare providers.

In order to expand BHI and improve CHW training, I urge the South Sudanese government to commit long-term funding. Partners, including WHO and World Bank need to invest in capacity-building initiatives. Finally the SSDA must support CHWs as a critical part of the healthcare system.

The Demographic and Health Survey Program (DHS) has been a mainstay for tracking malaria indicators in endemic countries over the past three decades. When visiting the website now, one is met with the following message, “Due to the on-going review of US foreign assistance programs, The DHS Program is currently on pause. We are unable to respond to any data or other requests at this time. We ask for your patience.” Surveys completed and published before the end of 2024 are still available to view and download, but work that wan is progress has halted.

The example of Nigeria is instructive. One finds a table on the Nigeria Country page that summarizes 25 national level health and development indicators from 1990 to 2021 using either the DHS or the Malaria Indicator Survey (MIS). A 2024 DHS survey was undertaken and a preliminary report is available, but the final detailed report was not written before the transition in administrations.

The 1990-2021 summary table included one malaria variable, children under five years of age sleeping under an insecticide-treated net the night prior to the study. Out of interest the information is posted in a chart herein. Of note, no bednet data were available for 1990. fortunately the 2024 preliminary MIS includes this.

Of note is the coverage in the context of earlier targets of 80% in 2010 and subsequent efforts to cover all children as time passed. The chart shows a slow start reaching only 29% of children by 2010 and then dropping to 17% in 2013. over the next four surveys, the coverage rate hovered in the mid 40% range topping 50% only once.

The Nigeria  National Malaria Control Program changed its name some time ago to National Malaria Elimination Program in hopes that this new moniker might lead to improved efforts. Unfortunately this was not to be the case. The value of the DHS/MIS was that countries could easily see progress and challenges and plan accordingly.

The Federal Ministry of Health, Nigeria, in collaboration with the National Population Commission (NPC) have been the local implementers of these surveys over the years. In addition to USAID, other partners such as WHO, UNFPA, The Bill & Melinda Gates Foundation, and the Global Fund have provided assistance in conducting the surveys.

Hopefully Nigeria (and other countries) and various partners will continue to see value in obtaining national and sub-national health and development statistics that document progress and help plan the future efforts to rid endemic populations of malaria and other scourges.

In the lead up to World Malaria Day 2025, the Johns Hopkins Malaria Research Institute held an Expert Briefing for the Media to discuss  the Global State of Malaria: New Research, Evolving Risks, and Silver Linings. The session was moderated by Ellen Wilson.

The two experts included Jane M. Carlton, PhD, director of the Johns Hopkins Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health and a Bloomberg Distinguished Professor in the Department of Molecular Microbiology and Immunology at the School and George Dimopoulos, PhD, MBA, also a professor in the Department of Molecular Microbiology and Immunology.

The speakers discussed and responded to questions regarding the current state of malaria, the need for global commitment to malaria prevention, control, and research, advancing diagnostics and therapeutics, current mosquito vector control methods and their limitations, and the need for an integrated approach to malaria control. As an overview, attendees were told that malaria is a mosquito-borne disease that in 2023 took nearly 600,000 lives in 83 countries, the majority being children under age 5 years in the WHO African Region.  In the U.S., the risk of contracting malaria remains low; however, continued vigilance is needed to prevent increases in both domestic cases from foreign travel and as occurred in 2023 for the first time in 20 years, locally transmitted cases.

Jane Carlton expressed concern that malaria cases had increased from 2022 to 2023, but was hopeful because of innovations such as vaccines, and genetically modified mosquitoes. One could also draw hope from efforts to establish local manufacturing capabilities in endemic countries, including partnerships for African vaccine development and production. And in fact, she noted, in 2022, “one company in Kenya became the first African-based manufacturer to receive WHO pre-qualification for a malaria drug. There is a second Nigerian manufacturer that is making progress.” There are several research organizations and universities in African countries that are working towards new drug and intervention development. Studies are ongoing perhaps to use some local plants as anti-larval treatments.

Prof. Carlton explained that the burden of malaria in India has reduced dramatically. “There’s been about a 70% reduction in cases from just over 6 million in 2017 to 2 million in 2023,” although two million cases is still quite a large number.

Prof. Carlton was also asked about the effect climate change on malaria transmission and the potentially expanding the geographic range of malaria. How are researchers adapting? She observed that, “Yes, that’s a very interesting question. In fact, it goes against intuition in a way but increasing the temperature doesn’t always increase the number of malaria cases. The malaria parasite and the mosquito that carries operate within quite a tight temperature range.

In reality, it can get too hot, but as some areas get wetter and formerly cool areas become warmer due to climate change, malaria transmission can move to new locations. “So, there is an increasing shift and an increasing understanding that surveillance of this particular issue is important,” especially needing to monitor climate contexts. For example, scientists have looking at the invasive Anopheles stephensi, which is severely disrupting activities of National Malaria control programs.

There’s been an analysis from the Oxford Malaria Atlas Project, or MAP, and they have projected that with a freeze for one year of PMI activities, this would result in up to 18 million additional malaria cases and up to 107,000 additional malaria deaths. This represents an increase in morbidity of 13%. This would occur in PMI’s focus geographies across 27 African countries. This analysis doesn’t account for the additional impact of PMI supported diagnostics.

Prof. Carlton observed that “globally, total investments in malaria control reached an estimated $4 billion in 2023, but this already fell short of the $8 billion funding target” of the World Health Organization Roll Back Malaria Partnership.

George Dimopoulos stressed e importance of community engagement in vector control activities. He explained that malaria is one of the diseases of poverty where the poor are disproportionately at risk and impacted. He then responded to a question about gene-drive technology based on the

CRISPR-Cas9 system that can spread mosquito genes in natural populations. “This has advanced very significantly in mosquitoes over the past roughly 10 years.”

Prof. Dimopoulos explained that gene-drive “can also work in all malaria vector species. In this way it becomes a malaria control strategy that could work in all malaria endemic areas.” Prof. Dimopoulos’ team has also done research on the effects of sugars and micro-organisms on the mosquito gut and malaria transmission. “We have shown through our research that the health of the mosquito gut depends on a protein quality control system. With appropriate control interventions, “The mosquitoes become very sick and a large proportion of them will actually die.”

In conclusion, the “Silver Linings” mentioned in the session’s title include advances in both parasite and vector control. Deployment of two malaria vaccines offers one ray of hope. New vector control technologies such as gene-drive, offer another. The speakers encouraged people to attend the upcoming JHU-MRI Malaria Day conference to learn more.

The RBM Partnership to End Malaria has developed a communication kit to help plan for the upcoming World Malaria Day on April 25th. Below are some of the highlights and links they have shared.
To mark World Malaria Day 2025,  the RBM Partnership to End Malaria in collaboration with World Health Organization (WHO) have developed a Messaging Framework and Social Media Toolkit to support partners and individuals in raising awareness and advocating for a malaria-free world.

Objectives for this year include…

• Re-energize efforts at all levels, from global policy to community action, to accelerate progress towards malaria elimination
• Advocate for increased investment in malaria control and elimination programs, including through stepped-up domestic financing and successful replenishments for the Global Fund and Gavi in 2025.
• Promote innovative strategies and approaches to tackle evolving challenges in malaria
• Prioritize country ownership, actively engage communities, and implement data-driven strategies

The emphasis is on three pillars. First in REINVEST, which recognized that “Malaria control and elimination programs don’t just save lives – they’re also a smart economic investment for malaria-endemic countries and their international partners.”

The second pillar calls on us to REIMAGINE. We must Accelerate innovation by investing in the research and development of new and more effective antimalarial drugs, diagnostics, insecticides, vaccines and vector control methods” and turning that research into action.

The third pillar is a call to REIGNITE based on “a renewed sense of urgency and commitment is needed to accelerate the fight against malaria.” This is called the “Big Push against malaria (and) is a multistakeholder effort to drive progress.”

Follow the links to learn more and plan action.