A malaria elimination framework that includes high prevalence countries, too

When the Nigeria Malaria Control Program changes its name to Nigeria Malaria Elimination Program (NMEP) a few years ago, people wondered whether this was getting too far ahead of the situation in one of the highest burden malaria countries in the world. The recently released Framework for Malaria Elimination by the Global Malaria Program of WHO shows that all endemic countries can fit into the elimination process.

Recent Webinar by WHO’s Global Malaria Program stressed that all countries have a role in malaria elimination

The Framework stresses that, “Every country can accelerate progress towards elimination through evidence-based strategies, regardless of the current intensity of transmission and the malaria burden they may carry.” The Three pillars of the malaria elimination framework have room for high burden countries. Pillar 1 states that, “Ensure universal access to malaria prevention, diagnosis and treatment.”

First it is important to understand that the Framework defines malaria elimination as the cessation of indigenous mosquito-borne transmission of malaria throughout a country. The Framework also observes that even within countries there are diverse transmission areas. Some are not amenable to malaria transmission, while others may be amenable but do not experience transmission.

It is important to realize that malaria transmission in most countries is characterized by diversity and complexity. Areas where transmission is occurring range from very low transmission zones where hotspots erupt to high levels of ongoing transmission. Thus even high burden countries may have variation that require development of intervention packages tailored to the specific transmission setting.

This stratification and development of appropriate intervention packages requires, “Excellent surveillance and response are the keys to achieving and maintaining malaria elimination; information systems must become increasingly ‘granular’ to allow identification, tracking, classification and response for all malaria cases (e.g. imported, introduced, indigenous).” This should lead to “subnational elimination targets as internal milestones.”

For high burden countries key components of Pillar 1 is, “Vector control strategies, such as use of insecticide-treated mosquito nets (ITNs/LLINs) and indoor residual spraying (IRS), together with case management (prompt access to diagnosis and effective treatment) are critical for reducing malaria morbidity and mortality, and reducing malaria transmission.”

Recommendations like ensuring political commitment, private sector involvement and establishment of an independent advisory committee are valuable at all stages of elimination. A challenge for high burden countries will be maintaining political commitment over many years. Early involvement of the private sector will boost coverage of major interventions. An independent advisory/monitoring group will help track data and progress.

It is important to put in place good monitoring systems to ensure that program coverage is well targeted, achieved and maintained. “Systematic tracking of programme actions over time, including budget allocations and adherence to standard operating procedures.” This enables accountability and enhances political commitment.

Finally the Malaria Atlas Project has mapped most recent data, and as we can see Nigeria does have a variety of transmission settings. We know now that the decision of Nigeria’s malaria program to update its name was appropriate. Hopefully not only the NMEP but also the various state malaria programs will look at their malaria transmission strata and plan according toward elimination.

World Health Workers Week, a Time to Recognize Health Worker Contributions to Malaria Care

Since the beginning of the Roll Back malaria Partnership in 1998 there has been strong awareness that malaria control success is inextricably tied to the quality of health systems. Achieving coverage of malaria interventions involves all aspects of the health system but most particularly the human resources who plan, deliver and assess these services. World Health Worker Week is a good opportunity to recognize health worker contributions to ridding the world of malaria.

We can start with community health workers who may be informal but trained volunteers or front line formal health staff.  According to the Frontline Health Workers Coalition, “Frontline health workers provide immunizations and treat common infections. They are on the frontlines of battling deadly diseases like Ebola and HIV/AIDS, and many families rely on them as trusted sources of information for preventing, treating and managing a variety of leading killers including diarrhea, pneumonia, malaria and tuberculosis.”

The presence of CHWs exemplifies the ideal of a partnership between communities and the health system. With appropriate training and supervision CHWs ensure that malaria cases are diagnosed and treated promptly and appropriately, malaria prevention activities like long lasting insecticide-treated nets are implemented and pregnant women are protected from the dangers of the disease. CHWs save lives according to Nkonki and colleagues who “found evidence of cost-effectiveness of community health worker (CHW) interventions in reducing malaria and asthma, decreasing mortality of neonates and children, improving maternal health, increasing exclusive breastfeeding and improving malnutrition, and positively impacting physical health and psychomotor development amongst children.”

CHWs do not act in isolation but depend on health workers at the facility and district levels for training, supervision and maintenance of supplies and inventories. These health staff benefit from capacity building – when they are capable of performing malaria tasks, they can better help others learn and practice.

A good example of this capacity building is the Improving Malaria Care (IMC) project in Burkina Faso, implemented by Jhpiego and supported by USAID and the US President’s malaria Initiative. IMC builds capacity of health workers at facility and district level to improve malaria prevention service delivery and enhance accuracy in malaria diagnosis and treatment. Additionally capacity building is provided to health staff in the National Malaria Control Program to plan, design, manage and coordinate a comprehensive malaria control program. As a result of capacity building there has been a large increase in malaria cases diagnosed using parasitological techniques and in the number of women getting more doses of intermittent preventive treatment to prevent malaria during pregnancy.

Malaria care is much more than drugs, tests and nets. Health worker capacity is required to get the job done and move us forward on the pathway to eliminate malaria.

The Business Case for Malaria Prevention: Employer Perceptions of Workplace LLIN Distribution in Southern Ghana

Kate Klein as part of her Master of Science in Public Health program in Social and Behavioral Interventions at the Johns Hopkins Bloomberg School of Public Health undertook a study of the potential for private sector involvement in malaria prevention in Ghana. She shares a summary of her work here. During her practicum in Ghana she was hosted by JHU’s Center for Communications Programs and its USAID supported VectorWorks Program. Her practicum she was also supported by the JHU Center for Global Health, and she presented her findings in a poster at the CGH’s Global Health Day on 30th March 2017. Her essay readers/advisers were Dr. Elli Leontsini (Department of International Health) and Kathryn Bertram (Center for Communication Programs).

Malaria is endemic in all parts of Ghana and significantly burdens families, communities, and economies. Malaria remains a leading cause of morbidity and mortality in Ghana; it accounts for eight percent of deaths in the country (The Global Fund, Ghana). It was also responsible for about 38% of outpatient visits, 27.3% of admissions in health facilities, and 48.5% of under-five deaths in 2015 (Nonvignon et al., 2016). In Ghana, the estimated cost of malaria to businesses in 2014 alone was estimated to be US$6.58 million, and 90% of these were direct costs (Nonvignon et al., 2016). Malaria leads to reduced productivity due to increased worker absenteeism and increased health care spending, which negatively impact business returns and tax revenue to the state (Nabyonga et al., 2011).

Although long-lasting insecticidal treated nets (LLINs) are a well-documented strategy to prevent disease in developing countries, most governments, including Ghana, lack the resources needed to comprehensively control malaria. The Global Fund (GF), USAID/President’s Malaria Initiative (PMI Ghana), and the United Kingdom Department for International Development (DfID Ghana) are the main donors for the national malaria control strategy and have worked primarily with the public sector (World Malaria Report, 2015). As government funding remains unable to close the funding gap for malaria, there is an increasing need to revitalize the private sector in sales and distribution of this life-saving technology.

A “Journey mapping” exercise to consider the process of employers buying and distributing nets to employees, created during a PSMP advocacy workshop in December 2016

Ghana is looking to the private sector to encourage a departure from previous dependence on donor-funded free bed nets. The Private Sector Malaria Prevention (PSMP at JHU) project is being implemented in Southern Ghana to increase commercial sector distribution of LLINs. Three case studies served as a situation analysis and exemplified the potential for the PSMP: a rubber producing company, a mining company and a brewery.

All three had experience in malaria control and prevention but only one had specific experience with LLINs (which dovetailed well with its own corporate strengths in logistics management as exemplified by other bottling companies in Africa). Another supported the idea of adding LLINs to its existing indoor residual spraying and community health education efforts, but needed to consider how to develop the flexibility to engage in multiple malaria interventions.

The third had had the right climate and leadership to be able to partner with PSMP, but recently underwent a takeover by a large multinational brewing company and the resulting period of transition could potentially complicate their participation in LLIN distribution efforts from a budgetary standpoint. Generally these companies had the understanding of the potential benefits to the company of situating malaria control within their structure, and thus being early candidates for adoption of the PSMP.

While the three case study companies recognized the business case for malaria, this was not a unanimous opinion among other five companies interviewed. Their concerns ranged from a preference toward treatment interventions to concerns expressed by employees about the difficulty of achieving high levels of net usage due to an array of complaints surrounding sleeping under LLINs. Some of these others had financial constraints.

Through case studies and interviews PSMP was able to identify various challenges moving forward as well as areas where further clarity must be sought. PSMP learned that several companies are pouring their resources into strong treatment and case management programs, and one challenge will be determining how to push for preventative action, such as LLIN distribution, when treatment mechanisms are so established and bias exists.

For those companies who are making tremendous strides in malaria prevention, bringing recognition to these successes through advocacy will be necessary for encouraging future participation and convincing other similar employers of the benefits of starting their own LLIN distribution programs. Finally, PSMP needs to prioritize clarifying viewpoints on LLIN efficacy and use, with a focus on understanding why employers may hold unfavorable views and what it would take to overturn them.

In the future it will be necessary to move beyond the occupational considerations specific to mining and agro-industrial operations and consider how the work has changed the environment into a malaria habitat and the non-traditional work hours that may create more significant Anopheles mosquito exposures. PSMP should gather specific information on lifestyle, housing, and work environments during future visits with employers so that companies that have the most to gain through LLIN distribution are identified and targeted.

Myanmar – update on malaria indicators

Myanmar is one of the countries at the epicenter of the developing resistance of malaria parasites to artemisinin based drugs. This means there is a strong need for prompt, appropriate and thorough diagnosis and treatment of febrile illnesses and malaria as well as the regular use of effective malaria preventive technologies. The 2015-16 Demographic and Health Survey for the country is thus a timely source of information to improve malaria interventions. Highlights from the DHS follow.

The first major concern is both lack of insecticide treated nets as well as low use of those available as the pie chart from the DHS makes clear. Ironically 97% of households have some kind of net, but 73% do not have an insecticide treated one. Although the Global Fund has supported distribution of 4.3 million ITNs in the country, there are over 56 million people living there. The US President’s Malaria Initiative has procured nearly 900,000 ITNs for the country. Although low across all economic strata, the lowest wealth quintile have the highest ITN possession (35%).

The 2013 concept note submitted by Myanmar to Global Fund under the new funding mechanism identifies many of the challenges: “Factors that may cause inequity to services for treatment and prevention: There are several population groups, which are poorly served by the health system and malaria services such as those living in remote border areas, migrant populations, forest workers and miners where malaria transmission is intense. Many of them are internal and external migrants who usually have limited access to malaria prevention and control. Major factors include distance from health facilities and poor awareness of malaria and its prevention.”

Key strategies in the Global Fund Concept Note do address quality malaria diagnostics and appropriate treatment. Unfortunately DHS results do not yet show the impact of improved diagnosis and treatment. “Overall, 16% of children under age 5 had a fever in the 2 weeks before the survey. Advice or treatment was sought for 65% of these children with recent fever, and 3% had blood taken from a finger or heel, presumably for diagnostic testing.” A variety of public and private sources were used to seek fever treatment, but “Only 1% of children received antimalarial drugs for treatment of fever in the 2 weeks preceding the survey.”

In addition to formal donors, there are coalitions and consortia who provide encouragement, technical assistance, advocacy and capacity building for eliminating malaria in the Asia-Pacific region. While the country needs to take stronger leadership in malaria elimination, all groups need to come together and strengthen the malaria interventions in Myanmar as these have implications for eliminating the disease in the region as a whole.

World Tuberculosis Day: United We Can End TB and Tropical Diseases

The theme of World TB Day is to Unite to end TB: leave no one behind. The communities affected by TB are also ones where tropical diseases like onchocerciasis and malaria are endemic. A successful strategy to control one disease should ideally be “united” with all basic primary health care interventions, thereby truly leaving no one behind.

While the causative agents differ between TB and tropical diseases such as malaria, lymphatic filariasis and Dengue, control of these diseases shares a common goal – “an urgent need to develop new vaccines for HIV/AIDS, malaria, and tuberculosis, as well as for respiratory syncytial virus and those chronic and debilitating (mostly parasitic) infections known as neglected tropical diseases (NTDs).” In addition to prevention, there is also need for integrated “treatment pipelines directed at NTDs, Malaria, tuberculosis (TB), and human immunodeficiency virus (HIV)/AIDS,” according to Asada.

There is also a need for integrated primary health care (PHC) programming. In the Journal of Infectious Diseases. Simon reports on linkages showing that, “Recent research suggests that NTDs can affect HIV and AIDS, tuberculosis (TB), and malaria disease progression. A combination of immunological, epidemiological, and clinical factors can contribute to these interactions and add to a worsening prognosis for people affected by HIV/AIDS, TB, and malaria.”

The possibility of integrating directly observed treatment (DOT) for TB treatment into community health worker (CHW)/PHC programs that addressed malaria treatment and onchocerciasis control was tested by the Tropical Disease Research Program (TDR) some years ago. CHWs in a few of the study sites were able to successfully include DOT for TB in their community duties, but in other sites community and health worker fears about stigma inhibited action.

TB, malaria and NTDs are among the conditions referred to as the infectious diseases of poverty. We will not eliminate poverty by tackling these diseases one-by-one. A “United” and integrated approach from national to community level is needed.

World Water Day: Water and Neglected Tropical Diseases

The United Nations introduces us to the challenges of water. “Water is the essential  building block of life. But it is more than just essential to quench thirst or protect health; water is vital for creating jobs and supporting economic, social, and human development.” Unfortunately, “Today, there are over 663 million people living without a safe water supply close to home, spending countless hours queuing or trekking to distant sources, and coping with the health impacts of using contaminated water.”

Haiti: Importance of Water to prevent STH

Many of the infectious health challenges known as Neglected Tropical Diseases (NTDs) have issues of water associated with their transmission. This may relate to scarcity of water and subsequent hygiene problems. It may relate to water quality and contamination. It may also relate to water in the lifecycle of vectors that carry some of the diseases.

Even though water is crucial to the control of many NTDs, it is not often the feature of large scale interventions. The largest current activity against five NTDs is mass drug administration (MDA) on an annual or more frequent basis to break the transmission cycle.  Known as diseases that respond to preventive chemotherapy (PCT) through MDA, these include lymphatic filariasis (LF), trachoma, onchocerciasis, schistosomiasis and soil transmitted helminths (STH) has been undertaken for over 10 years.

We have recently passed the Fifth Anniversary of the London Declaration on NTDs, which calls for the control of ten of the many these scourges The Declaration calls for “the elimination “by 2020 lymphatic filariasis, leprosy, sleeping sickness (human African trypanosomiasis) and blinding trachoma.” Another water-borne NTD, guinea worm, should be eradicated soon. Two of the elimination targets are part of MDA efforts, LF and trachoma.

Cameroon: mapping the community to detect NTD transmission sites

Ministries of Health and their donor and NGO partners who deliver MDA against the 5 diseases in endemic countries express interest in coordinating with water and sanitation for health (WASH) programs. People do recognize the value of collaboration between NTD MDA efforts and WASH projects, but these may be located in other ministries and organizations.

The long term implementation of WASH efforts is seen as a way to prevent resurgence of trachoma, for example, and  strongly compliment efforts to control STH and schistosomiasis. Hopefully before the 10th Anniversary of the London Declaration the vision of “ensuring access to clean water and basic sanitation,” can also be achieved.

Finally as a reminder our present tools for the control of Zika and Dengue fevers relies almost entirely on safe and protected household and community sources of water to prevent breeding of disease carrying Aedes aegypti mosquitoes. If we neglect water, we will continue to experience neglected tropical diseases. Hopefully the topic of water and NTDs will feature prominently at next months global partners meeting hosted by the World Health Organization.


Zika and Access to Reproductive Health Services in Brazil

Twice a year students in the Johns Hopkins Bloomberg School of Public Health write blog postings as part of the course “Social and Behavioral Foundations of Primary Health Care.” We often share blog posts that relate to tropical health issues.  Below is a posting by class members Linda Cho, Linda Chyr, Rebecca Earnest, and Sarah Rosenberg on Zika, family planning, and reproductive health in Brazil.

In the 1960s, the Brazilian government adopted a laissez-faire attitude, which lead to the predominance of private organizations in the provision of family planning services. Since then, Brazil has witnessed one of the most dramatic reductions in family size in modern history in part due to increased access to family planning services. (Photo New York Times: Members of the Union of Mothers of Angels.)

However, in early 2015, the widespread epidemic of the Zika fever caused by the Zika virus in Brazil caused persisting gaps in access to contraception to resurface. Since it was first detected it has instilled fear and uncertainty in pregnant women whose fetuses could be at risk of Zika-related birth defects like microcephaly should the virus be contracted during pregnancy. This makes access to comprehensive reproductive health services and education a critical need for women who are pregnant or considering becoming pregnant.

While contraceptive use is fairly high in Brazil with 75.2% of women using modern forms of contraception, barriers to access remain. Some women face challenges, some of which include but are not limited to incomplete insurance coverage or lack of reimbursement for long-acting reversible contraceptives (LARCs), high up-front costs, low number of contraceptive service sites, and/or a lack of supply of the implants in the public sector . This may be one driver behind why LARCs only make up 0.5% of all contraceptive sales. Furthermore, 55% of all pregnancies in Brazil estimated to be unplanned and 20% of all lives births are attributed to teenage girls, indicating that there may be substantial reproductive knowledge gaps  in how to effectively prevent pregnancy.

Amid the spread of a virus that poses unique health risks to pregnant women and their fetuses, there is an urgent need to address these gaps in reproductive health access and education. First, the Brazilian National Health System, which laudably provides most contraceptives free of charge to about 74% of the population, needs to reevaluate existing policies that may be still limiting access to contraceptive services. Secondly, organizations like the Brazilian Society for Family Welfare (BENFAM), which provides reproductive health services and education to underserved Brazilian communities, need greater financial and political support from policymakers, civil society, and even organizations traditionally opposed to such services like the Catholic Archdiocese.

Despite Brazil’s great strides to improve access to contraception and reproductive health education in recent years, Zika’s arrival highlighted gaps in the existing system that must be addressed through policy reform and greater political and financial support. Especially in the time of Zika, Brazilian women deserve no less.

What are national governments willing to pay for malaria control?

In 2013 national/domestic funding accounted for 20.4% of the US$2.6 billion in global support used to control and eliminate malaria, although it is not clear whether this is governmental, private or a mix.[i] The 2016 World Malaria Report (WMR) reports that, “Total funding for malaria control and elimination in 2015 is estimated at US$ 2.9 billion.[ii] This total represents just 46% of the Global Technical Strategy for Malaria 2016–2030 (GTS) 2020 milestone of US$ 6.4 billion.”

If domestic funding at the previous rate were to meet this milestone, endemic countries would need to put forward $US1.3 billion themselves, not to mention the fact that domestic funding may be needed even more as uncertainties increase in bilateral and multi-lateral sources. Of the coming from governments, US$ 612 million was direct expenditures through national malaria control programmes (NMCPs) while US$ 332 million was expenditures on malaria patient care. While domestic funding for malaria in African countries has increased in absolute terms over the years, it still remains a smaller proportion of total funding.[iii]

Governments in endemic countries characterized by a large portion of the poor, may in fact not contribute a fair share of malaria expenditure. Households are often said to bear the brunt of malaria financing through out-of-pocket expenditure for both treatment and prevention. While we do not have specific figures for malaria, we note that the overall out-of-pocket (OPP) expenditure by households in Nigeria for health care averaged 69.3% between 2010 and 2014.[iv]

Ghana has a national health insurance scheme that may reach up to two-thirds of the population. Costs of fever/malaria episodes therefore should covered by membership, although one is required to pay annual premiums.[v] Still a large portion of the population still pays out-of-pocket.

Although malaria funding from all sources has been increasing over the years, it has recently stagnated at a level approximately 45% of that level targeted to eventually eliminate the disease.  In many countries households still bear the brunt of malaria costs, both for treatment and prevention.

Benefits of investments in interventions like community health workers do help bring malaria care closer to the community at a cost people can afford.[vi] More financial support is needed to scale these up, especially by mobilizing in-country governmental, corporate and non-governmental resources.

[i] Kates J and Wexler A. Global Financing for Malaria: TRENDS & FUTURE STATUS.

Kaiser Family Foundation, December 2014 http://kff.org/report-section/global-financing-for-malaria-introduction/

[ii] World Health Organization. World Malaria Report 2016. ISBN 978-92-4-151171-1. Geneva: World Health Organization, 2016

[iii] Korenromp EL, Hosseini M, Newman RD, Cibulskis RE. Progress towards malaria control targets in relation to national malaria programme funding. Malaria Journal 2013, 12:18 Page 2 of 9 http://www.malariajournal.com/content/12/1/18

[iv] World Health Organization. Global Health Expenditure Database: Nigeria. Accessed 6 February 2017. http://apps.who.int/nha/database/Key_Indicators_by_Country/Index/en?COUNTRYKEY=84700

[v] Tawiah T, Asante KP, Dwommoh RA, Kwarteng A, Gyaase S, Mahama E, Abokyi L, Amenga-Etego S, Hansen K, Akweongo P, Owusu-Agyei S. Economic costs of fever to households in the middle belt of Ghana. Malar J. 2016 Feb 6;15:68. doi: 10.1186/s12936-016-1116-x.

[vi] Sunguya BF, Mlunde LB, Ayer R, Jimba M.. Towards eliminating malaria in high endemic countries: the roles of community health workers and related cadres and their challenges in integrated community case management for malaria: a systematic review. Malar J. 2017 Jan 3;16(1):10. doi: 10.1186/s12936-016-1667-x.

Malaria in Pregnancy Progress in Nigeria – the 2015 Malaria Indicator Survey

With an eye toward the future Nigeria’s National Malaria Control Program also refers to itself as the National Malaria Elimination Program (NMEP). Given that Nigeria has the highest burden of malaria in Africa, along with around one-quarter of sub-Saharan Africa’s population, the elimination goal will take a lot of work.

Recently the 2015 Malaria Information Survey (MIS) for Nigeria was released and gives a perspective on how far we have some and how far we need to go. We will focus on malaria in pregnancy (MIP) interventions today.

Intermittent Preventive Treatment for pregnant women (IPTp) using sulfadoxine-pyrimethamine (SP) remains the key MIP intervention due to the high and stable malaria transmission that still persists. There is always a challenge in delivering health interventions that require multiple contacts, and IPTp is not exception. The difficulty in achieving two doses when that was policy was clear. Now that WHO recommends monthly dosing from the second trimester forward (giving the possibility of 3, 4 or more doses), the service delivery challenge is heightened.

We can see in the attached graph from the MIS report that while there is progress, it remains well below the 2010 Roll back malaria Target of 80%. Part of the problem resides in the fact that the 2013 DHS showed only 61% of pregnant women attended even one antenatal care visit while 51% attended four or more.

The second lesson of the graph is missed opportunities. There is a gap between IPTp1 coverage of 37% and at least one ANC visit of 61%. Granted, 18% of women made their first visit in the first trimester when SP is not given, but not all of those stopped ANC then. The next evidence of missed opportunities is the gap between IPTp1 and IPTp2, almost a quarter of women who started IPTp did not get a second dose. We cannot say that the women’s own attendance gaps account for all the missed opportunities; some are likely due to health systems weaknesses such as stock-outs and health staff attention.

Key demographic factors are linked to receiving two or more IPTp doses. Only 30% or rural women received two or more compared to 50% of urban. There was a steady progression from 21% of the poorest women to 55% of those in the highest wealth quintile. A second chart also shows variation by section of the country. These access gaps are why we have advocated for supplementary distribution of IPTp through trained community health workers.

Use of insecticide treated bed nets by pregnant women shows a similar increase over time. The dip in 2013 probably related to fact that mass campaigns had occurred between 2009 and 2011 and thus by the time of the survey some nets had become damaged and abandoned. A major challenge in achieving net coverage is NOT relying on periodic distribution campaigns only, but ensuring regular and reliable supplies during routine services such as antenatal care. This again is a health systems problem that must be solved.

Net access is not only a health systems issue, bit may be factor of internal household dynamics. Even when the household possesses nets, only 63% of pregnant women therein slept under one the night before the survey. Community education needs strengthening – more than just telling people what to do but involving them is solving the problems of net use.

So as mentioned earlier, progress is being made, but more effort is needed. We are especially concerned because of the precariousness of global financial support for disease control. Nigeria needs to strategize how it can meet its own needs in protecting pregnant women and their unborn children from malaria, disability and death.

Malaria, Dengue, Mosquitoes – evolving in the urban environment

As the world increasingly urbanizes, we need to address the role of urban ecosystems and the evolution of disease vectors and organisms.  Marina Alberti and colleagues explained that …

“Recent studies show that cities might play a major role in contemporary evolution by accelerating phenotypic changes in wildlife, including animals, plants, fungi, and other organisms. Many studies of ecoevolutionary change have focused on anthropogenic drivers, but none of these studies has specifically examined the role that urbanization plays in ecoevolution or explicitly examined its mechanisms.”

In their own study they looked at “five types of urban disturbances including habitat modifications, biotic interactions, habitat heterogeneity, novel disturbances, and social interactions.” The researchers learned that, “clear urban signal; rates of phenotypic change are greater in urbanizing systems compared with natural and nonurban anthropogenic systems.” They concluded that there is need to continually “uncover insights for maintaining key ecosystem functions upon which the sustainability of human well-being depends.”

Of particular concern in the area of tropical health are the unique urban manifestations of diseases like yellow fever, dengue and malaria. Although Zika virus, for example, was first discovered in forests, it has adapted to an urban cycle involving humans and domestic mosquito vectors in tropical areas where dengue is endemic. Musso and Gubler in their review further explain that although there may be sylvatic cycles of Dengue, “Arboviruses such as DENV have adapted completely to humans and can be maintained in large tropical urban centers in a mosquito-human-mosquito transmission cycle that does not depend on nonhuman reservoirs.”

Weaver et al. note that Zika in spreading to Asia, “emerged on multiple occasions into urban transmission cycles involving Aedes (Stegomyia) spp. Mosquitoes.” In addition it can be hypothesized that phenotypic changes in Asian lineage ZIKV strains made rare disease outcomes such as congenital microcephaly and Guillain-Barré more common and visible.

According to Estelle Martin and co-researchers, “Puerto Rico, a major metropolitan center in the Caribbean, has experienced increasingly larger and clinically more severe epidemics following the introduction of all four dengue serotypes.” They found that Dengue serotype 4 replaced earlier strains and that “this epidemic strain progressed rapidly, suggesting that the epidemic strain was more fit, and that natural selection may have acted on these mutations to drive them to fixation.”

In addition to virus evolution, mosquito changes have been documented by Caroline Louise and colleagues in “One of the world’s largest urban agglomerations infested by Ae. aegypti … the Brazilian megalopolis of Sao Paulo.”  They detected microevolution despite a short observational period and stress the implications of the “rapid evolution and high polymorphism of this mosquito vector on the efficacy of control methods.”

“The adaptation of malaria vectors to urban areas is becoming a serious challenge for malaria control,” is a major concern of Antonio-Nkondjio and co-workers. They found, “rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé,” Members of this team also learned that the M form of Anopheles gambiae predominated in the centre of urban agglomerates in Cameroon. Previously it was known that larval habitats polluted with decaying organic matter as found in densely populated urban agglomerates, were unsuitable for Anopheles gambiae. The recent study showed that the “M form showed greater tolerance to ammonia (arising from organic matter) compared to the S form. This trait may be part of the physiological machinery allowing forest populations of the M form to colonize polluted larval habitats.”

The evolutionary response of vectors and disease organisms to urban environments needs continued monitoring. Urban disease control and elimination efforts must adapt to such adaptations in the disease process.