Tropical Health Matters

Originally published on 21 March 2026 by Nosheen Khan for the JHU/BSPH course “Social and Behavioral Foundations of Primary Health Care.”

Pakistan remains one of only two countries where wild poliovirus still circulates. In southern Khyber Pakhtunkhwa—districts like Bannu, North and South Waziristan, Tank, Lakki Marwat, and Dera Ismail Khan—vaccine refusals and low routine immunization coverage continue to fuel transmission. In some areas, routine coverage is critically low, leaving large numbers of “zero-dose” children.

For years, the response has relied on repeated mass campaigns. While these efforts have saved millions of children globally, in southern KP they are no longer enough. Communities face fatigue, misinformation, and deep-rooted distrust. Many families ask a simple question: “Why only polio drops, but no other health services?”

Evidence from the Global Polio Eradication Initiative and World Health Organization shows that access, trust, and behavior change are as critical as vaccines themselves. Similarly, UNICEF Pakistan highlights the importance of community engagement and social mobilization in addressing refusals.

A Needed Shift: From Campaigns to Communities

Southern KP needs a programmatic shift, not a new law. The provincial government—through the Khyber Pakhtunkhwa Department of Health and the Pakistan Polio Eradication Programme—should transition toward a community-centered, integrated service model:

• Combine polio vaccination with routine immunization, nutrition, and maternal-child health services
• Engage Jirga councils and religious networks to counter misinformation
• Invest in female frontline workers to improve access in conservative areas
• Strengthen routine immunization systems to rebuild trust

This approach addresses the root causes of refusal, not just the symptoms.

Why This Matters Now

With ongoing transmission and persistent immunity gaps, the cost of inaction is high—not just for Pakistan, but globally. A child missed today is a risk tomorrow.

Call to Action

The Khyber Pakhtunkhwa Department of Health and Pakistan Polio Eradication Programme must revise implementation guidelines within the next 6–12 months to integrate polio efforts with broader health services in southern KP. Development partners should align funding and technical support to accelerate this shift.

Ending polio in Pakistan will not come from more campaigns alone—it will come from building trust, delivering services, and putting communities at the center.

Bright Orji, PhD, FAIPH, FAPH, President, Health Promotion and Education Alumni Association, Ibadan College of Medicine (HPEAAICM) has written a brief obituary for our colleague, Sakiru Otusanya.

Dear Colleagues,

It is with a heavy heart that I announce the passing of our friend and colleague, Mr. Sikiru Otusanya, fondly known as “Otu.”

Otu was a member of the 1998/1999 MPH set and worked with UNICEF during his career. He will be fondly remembered for his contributions to public health, particularly his work on Guinea worm eradication, as part of the broader global efforts in which Nigeria played a significant role.

In addition, Otu applied his MPH skills as an essential Front-line staff of the Carter Center supported successful Nigeria Guinea Worm Eradication Programme NIGEP through community organizing and health education. He continued his   NIGEP water and  sanitation  work after guinea worm was eliminated in Nigeria as a nation consultant for UNICEF, traveling throughout the country.

Organizing community water supply to prevent Guinea Worm

Otu was an active and financially committed member of our Alumni Association and contributed immensely to laying a strong foundation for the Association.

He passed away yesterday, Saturday, 20 December 2025, and was buried today in Ijebu Ode, in accordance with Muslim rights

Our prayers are with his wife Dupe and their children and his many friends and family in Igbo-Ora, Ijebu Ode, across the continent and global community.

He will be greatly missed.

Asymptomatic malaria poses a major challenge for the elimination of malaria especially in low transmission settings and places where the move toward elimination looks most promising. When communities and front-line health staff do not “see” malaria, the disease will persist. This holds true for falciparum as well as vivax and on all continents where malaria is prevalent. Some examples of the problem from recent publications are shared here.

Saavedra-Samillán and colleagues describe the challenge in Peru as well as the broader Amazon Region. They tested and found Plasmodium vivax most frequently using both microscopy and qPCR. Submicroscopic malaria infections were highly prevalent and most were asymptomatic. The conclusion was the need for more accurate diagnostic as well as broader surveillance methods and “better detect and control hidden malaria transmission.”

Muhye and co-researchers address the “significant challenge to malaria control and elimination efforts due to its role in sustaining silent transmission within communities” in Ethiopia. Their study revealed that “asymptomatic schoolchildren serve as significant reservoirs for malaria, challenging elimination efforts.” Also of note, these older school-aged children seem less likely to benefit from insecticide treated bed nets that their pre-school aged counterparts. Thus their findings go a step beyond identifying the problem but point to weaknesses in interventions that could prevent it.

In Tanzania, Lin et al. raised the concern that “asymptomatic malaria carriers often harbor low parasite densities missed by rapid diagnostic tests.” Using colony-reared Anopheles gambiae, they demonstrated that “parasites circulating at the limit of PCR detection commonly infect mosquitoes,” and furthermore “a small proportion of highly infectious carriers contribute disproportionately to transmission” opening opportunities for targeted intervention.

Jiram and colleagues examined “Persistent low-density infection in areas at risk of malaria reintroduction in Malaysia.” Malaysia is where Plasmodium knowlesi (zoonotic malaria) and low-density infections pose reintroduction risks in previously malaria-free areas. They note that “Asymptomatic low-density malaria infections persist in purportedly malaria-free communities, remaining undetectable by routine microscopy. These hidden parasite reservoirs pose a risk for malaria reintroduction,” and recommend more sensitive diagnostic tools for malaria surveillance programs as well as focusing interventions on the hot-spots thereby identified.

While most of the recent articles focus on Africa, we can see that asymptomatic malaria poses a global problem that threatens elimination efforts. Not only do diagnostic and surveillance efforts need to account for infections that are more difficult to detect, but intervention tools such as bed nets and immunization need to be better targeted in order to save more lives leading up to 2030 and beyond.

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])

Malaria is one of the more than 30 diseases and conditions included in the Elimination Initiative and targeted for elimination in the Region of the Americas by 2030. Colombia provides a useful example of the progress and challenges. Of the over 72,000 reported malaria cases in 2022, About 61% were caused by P. vivax, 38% by P. falciparum, and 1% were mixed. The Ministry of Health explains that unlike other South American countries, the most malaria endemic regions are not in the Amazonian forest but lie in the northwest of the country in the Pacific coastal forests, populated by Afro-Colombian and indigenous communities.

The Ministry also notes that malaria transmission is characterized by the presence of epidemic cycles that occur every 2 to 7 years, related to the occurrence of the Niño-Southern Oscillation phenomenon. Malaria control is particularly challenging in provinces where illegal mining, logging and the growing of illicit crops are conducted. The World Malaria Report of 2023 traced annual malaria trends in Colombia and showed a peak in 2018-19 with a reduction in subsequent years that points toward efforts at elimination

The International Rescue Committee identifies a particular challenge for Colombia. At least 4 million Venezuelans have crossed the border to seek refuge, and that number continues to rise. Venezuela continues to be plagued by malnutrition, lack of medical supplies, high homicide rates and the spread of diseases such as malaria and measles. Since outbreaks of measles, diphtheria and malaria have been reported across Venezuela, it would be surprising that refugees would enter Colombia with malaria infections.

A study of malaria among migrants in a university hospital in Colombia during 2018 found that imported malaria has increased in Colombia since 2015 and has been attributed to migrants coming from Venezuela. To address the challenge, we need to know where are the refugees? Regular migration is usually located in the main cities and in places where tourism or the mining industry are active. Many of the destinations are in areas where malaria is not endemic, onward transmission would be less likely. Unfortunately, the following migration destinations overlap with malaria transmission: Nariño, Antioquia, Cundinamarca, Cauca, and Chocó, such that those migrants can acquire new infections.

The challenge is that as Colombia makes progress toward eliminating malaria, it still must maintain high capacity to tackle imported cases as well as new cases among a particularly vulnerable refugee population.

Bradley Blankenship contributed a blog posting on the continued challenges of Dengue in Brazil for the course, “Social & Cultural Basis for Community and Primary Health Programs,” at the Johns Hopkins Bloomberg School of Public health. Below are his concerns and observations.

A child receiving the dengue vaccine in Brazil, courtesy Nature.com

Brazil is currently facing a record-breaking number of dengue cases. In 2024, the country reported 5.1 million cases, with over 2,800 deaths associated with dengue. This is an all-time high for the country and surpasses projections. As a response, the government attempted changes to its national immunization program with the implementation of the Qdenga vaccine (Takeda’s new dengue vaccine). In fact, Brazil secured the entire global supply of Qdenga in 2024 to address rising numbers of cases and complications. This campaign is a crucial step for Brazil, but it is not without its challenges.

Safety and trust are major issues with new Dengue vaccine rollouts, as Qdenga follows a controversy in the Philippines after a previous vaccine, Dengvaxia, was withdrawn when it was found to increase the risk of severe Dengue in dengue-naïve children. This controversial rollout eroded public confidence in dengue vaccines. In contrast, Qdenga has been proven safe, even for those who have never been infected, and does not require pre-vaccination testing. This is a critical advantage of Qdenga and a crucial point to consider when rebuilding trust.

The global supply of Qdenga is limited, though, and Takeda is only able to produce about 6 million doses each year. This means that only 3 million people may receive the two-dose series recommended by the developers. The initial campaign, therefore, only covers a fraction of Brazil’s population. Furthermore, two-dose uptake by the population is also a concern, with only 714,000 reported second doses administered vs 2.16 million first doses reported, underlining the need for better follow-up and public education.

Moving forward, we need the Brazilian Ministry of Health to act on multiple fronts to address the dengue outbreak in Brazil. We need expanded access to Qdenga vaccines by securing more doses and broadening eligibility, rebuilding vaccine trust and compliance through education and community partnerships, and further support for the development of single-dose vaccine being developed by the Butantan Institute that would allow for improved compliance and domestic production, ultimately securing the ability to produce more vaccines as needed.

With millions of Brazilians vulnerable to dengue fever, decisive leadership from Brazil’s Ministry of Health is essential to adequately address the outbreak.

This brief posting is an abstract from a Capstone Project for the Master of Public Health Degree at the Johns Hopkins Bloomberg School of Public Health by Lauren Akua Koranteng.

Based on evidence globally, cancer is a leading cause of death, with significant disparities in low- and middle-income countries like Ghana, West Africa, where breast, liver, and cervical cancers are common. According to the Global Cancer Observatory, in 2022, the three leading causes of cancer in Ghana for both sexes were cancers of the breast, liver and cervix. Out of a population of over thirty-two million, there were 27,385 new cases, and the number of deaths was 17, 944.

This study assesses the readiness of Ghanaian health facilities to deliver cancer services using 2022 data from the WHO Harmonized Health Facility Assessment (HHFA). The analysis included 1,421 facilities across all sixteen regions in the nation, evaluating service availability, staff training, and resource allocation for cervical, breast, prostate, and colorectal cancers.

The results found that cancer services were discovered to be the lowest service availability among the noncommunicable disease (NCDs) with 17% of facilities offering cancer services. Cervical cancer services were very minimal, with 5% of facilities providing pap smears and 1% offering colposcopy procedures. Breast cancer services were slightly higher (15%). However, mammography was mostly unavailable in the various regions. Prostate and colorectal cancer were extremely low at 5% and 1%, respectively.

Greater Accra had the highest service availability (38% for any cancer), while regions like the Savannah region fell behind (14%). The government and regional hospitals have better resources and infrastructure in comparison to the community-based CHPS compounds.

In conclusion, several gaps exist in the nation with inadequate staff training and low drug availability (e.g., 3% tamoxifen) and a lack of national cancer registries. Based on these gaps in service availability, staff training, and resources, it would be best to recommend the prioritization of regional hospitals as cancer care centers, and a drive to expand the workforce in those areas to better manage cancer care in the nation.

Another recommendation would be to introduce HPV vaccinations and implement national screening programs. This will help to assist with meeting Ghana’s Universal Health Coverage goals and reduce cancer deaths.

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