Category Archives: Dengue

Malaria News Today 2020-09-11

Today’s news and abstracts look at a variety of issues ranging from overall malaria funding funding needs to the effect of climate change on different types of mosquitoes and the diseases they carry (e.g. malaria vs dengue). We also examine the need for surveillance among nomadic groups and the use of cell phones in a saliva based malaria testing system. Please click the links below to read more on each subject.

Rwanda: Government Needs U.S.$70 Million to Fill Malaria Financing Gap

By Nasra Bishumba: The Government needs $73 million to bridge the funding in the funds needed to fight malaria between 2020 and 2024, The New Times can reveal. The Rwanda National Strategic Plan 2020-2024 to fight malaria drawn up in June this year indicates that although the implementation requires Rwf295bn ($280 million), the government already has funding commitment to the tune of $206.8m (equivalent to 74 per cent).

According to the strategic plan, a copy of which The New Times has seen, this leaves a gap of $73m which it hopes to mobilize from different sources. With these funds, the government is seeking to protect at least 85 per cent of the population with preventive interventions and to work towards promptly testing and treating suspected malaria cases by 2024. To achieve this, the biggest chunk of the funds will be invested in malaria prevention to a tune of $186m, an equivalent of 66 per cent of the entire budget.

Climate Change May Shift Risks of Mosquito-borne Diseases

By Asher Jones: More dengue, less malaria. That may be the future in parts of Africa on a warming planet, depending on where you live. New research says it’s all about which mosquitoes will thrive. And the methods to control one don’t necessarily work on the other.

The mosquito that spreads malaria prefers relatively cool temperatures of 25 degrees Celsius (77 degrees Fahrenheit). The dengue mosquito does best at 29 degrees Celsius (84.2 degrees Fahrenheit). Because of this difference in optimal temperatures, “We would actually predict that climate change might have opposing effects [on disease transmission],” said Erin Mordecai, assistant professor of biology at Stanford University and lead author on the study. “Climate change might make it less suitable for malaria to be transmitted but more suitable for dengue to be transmitted.”

Africa’s Nomadic Pastoralists and Their Animals Are an Invisible Frontier in Pandemic Surveillance

@ASTMH The effects of COVID-19 have gone undocumented in nomadic pastoralist communities across Africa, which are largely invisible to health surveillance systems despite the fact that they are of key significance in the setting of emerging infectious disease. We expose these landscapes as a “blind spot” in global health surveillance, elaborate on the ways in which current health surveillance infrastructure is ill-equipped to capture pastoralist populations and the animals with which they coexist, and highlight the consequential risks of inadequate surveillance among pastoralists and their livestock to global health. As a platform for further dialogue, we present concrete solutions to address this gap.

Mobile phone-based saliva test wins NIH prize

Cornell researchers’ concept for a quick, non-invasive, mobile phone-based system to detect infectious diseases, inflammation and nutritional deficiencies in saliva was awarded a $100,000 National Institutes of Health Technology Accelerator Challenge prize. The NIH’s prize challenge encourages the development of new, non-invasive diagnostic technologies important for global health. For the group’s saliva-based test, a small 3D-printed adapter is clipped to a mobile phone and synced with a mobile app. The app uses the phone’s camera to image test strips to detect malaria, iron deficiency and inflammation, with results in under 15 minutes.

The proposal builds on the FeverPhone and NutriPhone platforms developed by the team at Cornell’s Institute for Nutritional Sciences, Global Health and Technology (INSiGHT). The technologies, funded by the NIH and the National Science Foundation, evaluate infections and nutritional status using blood. According to Mehta, technologies using salivary biomarkers could revolutionize how conditions such as malaria and iron deficiency are identified and addressed, especially in settings where access to primary health care and traditional, laboratory-based tests is limited.

Monsoon infections: How to tell the difference between dengue and malaria? Watch out for these symptoms

While both diseases are mosquito-borne and cause similar symptoms such as fever, joint/muscle pain, headaches, and fatigue, some differences between their symptoms can help you identify the specific infections. Unique symptoms of Malaria: Stomach problems such as vomiting, Diarrhoea, Dry cough, Shivering, Spleen enlargement Unique symptoms of Dengue: Pain behind the eyes, Swollen glands, Rashes

Malaria News Weekend 2020-09-05/6

We are sharing more updates from newsletters and journal abstracts found online. Issues include mapping malaria in connection with climate change, COVID-19 possibly inhibiting reporting o malaria cases, co-infection with coronavirus and malaria or dengue, Plasmodium knowlesi in northern India, and the effect of sanitation campaigns on infectious diseases. Click on links to read details.

Malaria kills 400,000 people a year, A new map shows where climate change will make it worse

A new study examines the impact of climate change on malaria in Africa. The maps reveal which areas will become more – or less – climatically suitable. Of an estimated 228 million cases of malaria worldwide each year, around 93% are in Africa. This proportion is more or less the same for the 405,000 malaria deaths globally.

That’s why there are huge efforts underway to provide detailed maps of current malaria cases in Africa, and to predict which areas will become more susceptible in future, since such maps are vital to control and treat transmission. Mosquito populations can respond quickly to climate change, so it is also important to understand what global warming means for malaria risk across the continent.

If it is too warm or too cold, then either the malaria parasite or the mosquito that transmits the parasite between humans will not survive. This suitable temperature range is relatively well established by field and laboratory studies and forms the basis for current projections of the impact of climate change on malaria. Yet, surface water is equally crucial as it provides habitat for the mosquitoes to lay their eggs. See original article in Nature Communications.

Malaria Situation in the Peruvian Amazon during the COVID-19 Pandemic

Malaria Situation in the Peruvian Amazon during the COVID-19 Pandemic. This article was originally published in Am J Trop Med Hyg. (2020 Sep 3. doi: 10.4269/ajtmh.20-0889). Online ahead of print. The Peruvian Ministry of Health reports a near absence of malaria cases in the Amazon region during the COVID-19 pandemic.

However, the rapid increase in SARS-CoV-2 infections has overwhelmed the Peruvian health system, leading to national panic and closure of public medical facilities, casting doubt on how accurately malaria cases’ numbers reflect reality. In the Amazon region of Loreto, where malaria cases are concentrated, COVID-19 has led to near-complete closure of the primary healthcare system, and diagnosis and treatment of acute febrile illnesses, including malaria, has plummeted. Here, we describe the potential association of COVID-19 with a markedly reduced number of reported malaria cases due to the reduced control activities carried out by the Peruvian Malaria Zero Program, which could lead to malaria resurgence and an excess of morbidity and mortality.

Dengue, malaria a new threat for Covid patients

Doctors in at least two Delhi hospitals have reported patients with twin infections of Covid-19 and dengue or malaria, a trend that could become worrying since the double disease may be deadlier, and the region is entering its most critical season for mosquito-transmitted diseases. The anecdotal reports tie in with latest findings that suggest a high prevalence of co-infections of diseases such as malaria, dengue and leptospirosis, which together have several symptoms that overlap with a symptomatic Covid-19 illness. Andhra villages see big drop in dengue, malaria, typhoid cases after pilot sanitation drive. Andhra govt data shows cases of seasonal diseases like dengue, typhoid, acute diarrhoea & malaria fell 97.4%, 96%, 81.7% and 50.4%, respectively, after the sanitation drive.

Now, months after the launch of the drive called ‘Manam Mana Parishubhratha’ (Our Cleanliness and Us), these villages have recorded a massive drop in the numbers of patients reporting with seasonal diseases like dengue, typhoid, malaria and acute diarrhoea. a 50.4% decrease in malaria cases (601), said the data.

AIIMS study finds zoonotic malarial parasite in acute febrile illnesses patients.

A zoonotic disease is a disease that can be spread/jump from animals to humans and vice versa. AIIMS researchers have sounded a note of caution after finding the presence of monkey malarial parasite ‘Plasmodium knowlesi’ in the north Indian population while doing a study on patients with acute febrile illnesses (AFI) and pathogens causing them.

The presence of the zoonotically transmitted malaria parasite was found during the study of acute febrile illnesses and causative pathogens in certain patients admitted in AIIMS from July 2017 to September 2018. The All Indian Institute of Medical Sciences (AIIMS) researchers from the Department of Biochemistry, along with clinicians from the Department of Medicine, were involved in the study on the pathogens causing severe fever.



Malaria News Today 2020-09-03

Various updates were found in newsletters and journal abstracts online today. These looked at mosquitoes – what attracts them to people, how ookinetes move in the midgut, and how perlite from volcanic rock may be a barrier repellent. Nigeria reports that there is no ACT resistance – so far.  And malaria partners join to coordinate actions in Uganda.  Click on links to read details.

Nigeria yet to detect resistance of malaria parasite to ACTs, says ministe

Contrary to reports that Africa has for the first time identified resistance strain of the malaria parasite to the drug of choice, Artemisinin Combination Therapy (ACT), the Minister of Health, Dr. Osagie Emmanuel Ehanire, on Monday said a study conducted in three states of the country showed there is no such phenomenon in Nigeria.  “However, we are still monitoring the situation. We insist that people should conduct a malaria test before using the drug of choice. This we hope will help prevent any kind of resistance of the malaria parasite to ACTs.”

Ministry of Health launches the Malaria Free Uganda Fund

Health Minister Dr Jane Ruth Aceng told journalists in Kampala today that the idea of having this new board was reached after realizing that different entities have been conducting the same malaria control related work. She said that the ministry resolved that mainstreaming responsibility will remove financial and operational bottlenecks that deter them from achieving set targets for elimination of the disease. The fund with a board of 11 members is chaired by Kenneth Wycliffe Mugisha of the Rotarian Malaria Partners-Uganda.

Volcanic Rock Yields a New Kind of Insecticide for Mosquitoes

Insecticide resistance to pesticides has become widespread in mosquito populations, making insecticides less effective over time. Therefore, there is an urgent need for insecticides with alternative modes of action. tested a material derived from volcanic rock, perlite, as a potential non-chemical insecticide against Anopheles gambiae, one of the primary mosquitoes that spreads malaria in Africa. In their new report published in August in the Journal of Medical Entomology, they show that perlite has encouraging potential as a mechanical insecticide. Perlite is believed to act by causing dehydration in the mosquitoes. read more…

Mosquitoes love pregnant, beer-drinking exercisers with Type O blood

Mosquitoes spread Zika, West Nile, Chikungunya, Dengue, and Malaria, resulting in 700 million illnesses a year and a million deaths. Even if you don’t get sick from a mosquito bite, the blood thinner they pump into your flesh before draining your blood causes swelling and itching. This article in Smithsonian Magazine lists the factors that make some people more tempting targets than others to mosquito bites. They include:

  • Blood type: “One study found that in a controlled setting, mosquitoes landed on people with Type O blood nearly twice as often as those with Type A.”
  • Carbon Dioxide: “people who simply exhale more of the gas over time—generally, larger people—have been shown to attract more mosquitoes than others.”
  • Exercise: “mosquitoes find victims at closer range by smelling the lactic acid, uric acid, ammonia and other substances expelled via their sweat”
  • Skin bacteria: “scientists found that having large amounts of a few types of bacteria made skin more appealing to mosquitoes”
  • Beer: “Just a single 12-ounce bottle of beer can make you more attractive to the insects”
  • Pregnancy: “pregnant people exhale about 21 percent more carbon dioxide and are on average about 1.26 degrees Fahrenheit warmer than others”
  • Clothing color: “wearing colors that stand out (black, dark blue or red) may make you easier to find”
  • Genetics: “underlying genetic factors are estimated to account for 85 percent of the variability between people in their attractiveness to mosquitoes”

Live In Vivo Imaging of Plasmodium Invasion of the Mosquito Midgut

Malaria is one of the most devastating parasitic diseases in humans and is transmitted by anopheline mosquitoes. The mosquito midgut is a critical barrier that Plasmodium parasites must overcome to complete their developmental cycle and be transmitted to a new host. Here, we developed a new strategy to visualize Plasmodium ookinetes as they traverse the mosquito midgut and to follow the response of damaged epithelial cells by imaging live mosquitoes. Understanding the spatial and temporal aspects of these interactions is critical when developing novel strategies to disrupt disease transmission.

Malaria News Today 2020-09-02

Updates from newsletters and journal abstracts found online today. Issues include health and malaria service disruptions from COVID-19, increased mosquito-borne diseases, including malaria, in India and mosquitoes and attractant odors. Click on links to read details.

Continuing vital health services in Guinea-Bissau during COVID-19

ReliefWeb explains that as lockdowns, curfews and transport disruptions prevent many vulnerable people from getting healthcare, communities are stepping into the breach. Community health workers and volunteers are ensuring their peers, friends, and neighbours are protected from disease. “In previous bednet distribution campaigns, we used to identify the families before setting up the distribution points,” said Ivannildo Vieira, a community health worker, “but this year, because of COVID-19 restrictions, it was decided to do door-to-door distributions in order not to gather people in a single distribution area.”

Helping communities protect themselves from diseases like malaria in Guinea-Bissau is no simple task. Located on West Africa’s coast, Guinea-Bissau is one of the world’s poorest and most fragile countries. Malaria is the leading cause of death among pregnant women and children under five. Malaria prevention measures have been complicated by a rapid increase in the number of COVID-19 cases.

Delhi records 24% rise in Dengue, Malaria in 7 days

While Delhi’s healthcare is overwhelmed with tackling the COVID-19 pandemic, another epidemic of vector-borne diseases are knocking at its door. A whopping rise of 24 per cent in Dengue, Malaria, and Chikungunya cases were recorded in the last one week.  The cities/corporations stated that they reported incidents of mosquito-breeding at 44,259 households and served 35,103 legal notices to the violators. Meanwhile, 1,512 prosecutions were launched against the violations.

Is Anopheles gambiae attraction to floral and human skin-based odours and their combination modulated by previous blood meal experience?

Malaria Journal notes that Mosquitoes use odours to find energy resources, blood hosts and oviposition sites. While these odour sources are normally spatio-temporally segregated in a mosquito’s life history, here this study explored to what extent a combination of flower- and human-mimicking synthetic volatiles would attract the malaria vector Anopheles gambiae sensu stricto (s.s.).

Nulliparous and parous A. gambiae s.s. are attracted to combinations of odours derived from spatio-temporally segregated resources in mosquito life-history (floral and human volatiles). This is favourable as mosquito populations are comprised of individuals whose nutritional and developmental state steer them to diverging odours sources, baits that attract irrespective of mosquito status could enhance overall effectiveness and use in monitoring and control. However, combinations of floral and skin odours did not augment attraction in semi-field settings, in spite of the fact that these blends activate distinct sets of sensory neurons. Instead, mosquito preference appeared to be modulated by blood meal experience from floral to a more generic attraction to odour blends. Results are discussed both from an odour coding, as well as from an application perspective.

Malaria Leaves 100 Dead in South Sudan

The East African reports that South Sudan’s Ministry of Health and the World Health Organization (WHO) say at least 100 people died of malaria in the  In a joint report released on Sunday, the two institutions said morbidity and mortality trends in the Protection of Civilians Sites across the country, as of July, indicated rampant deaths due to malaria infections.

The Weekly Tropical Health News 2019-06-29

Below we highlight some of the news we have shared on our Facebook Tropical Health Group page during the past week.

Polio Persists

If all it took to eradicate a disease was a well proven drug, vaccine or technology, we would not be still reporting on polio, measles and guinea worm, to name a few. In the past week Afghanistan reported 2 wild poliovirus type 1 (WPV1) cases, and Pakistan had 3 WPV1 cases. Circulating vaccine-derived poliovirus type 2 (cVDPV2) was reported in Nigeria (1), DRC (4) and Ethiopia (3) from healthy community contacts.

Continued Ebola Challenges

In the seven days from Saturday to Friday (June 28) there were 71 newly confirmed Ebola Cases and 56 deaths reported by the Democratic Republic of Congo’s Ministry of Health. As Ebola cases continue to pile up in the Democratic Republic of the Congo (DRC), with 12 more confirmed Thursday and 7 more Friday, a USAID official said four major donors have jump-started a new strategic plan for coordinating response efforts. To underscore the heavy toll the outbreak has caused, among its 2,284 cases, as noted on the World Health Organization Ebola dashboard today, are 125 infected healthcare workers, including 2 new ones, DRC officials said.

Pacific Standard explained the differences in Ebola outbreaks between DRC today and the West Africa outbreak of 2014-16. On the positive side are new drugs used in organized trials for the current outbreak. The most important factor is safe, effective vaccine that has been tested in 2014-16, but is now a standard intervention in the DRC. While both Liberia and Sierra Leone had health systems and political weaknesses as post-conflict countries, DRC’s North Kivu and Ituri provinces are currently a war zone, effectively so for the past generation. Ebola treatment centers and response teams are being attacked. There are even cultural complications, a refusal to believe that Ebola exists. So even with widespread availability of improved technologies, teams may not be able to reach those in need.

To further complicate matters in the DRC, Doctors Without Borders (MSF) “highlighted ‘unprecedented’ multiple crises in the outbreak region in northeastern DRC. Ebola is coursing through a region that is also seeing the forced migration of thousands of people fleeing regional violence and is dealing with another epidemic. Moussa Ousman, MSF head of mission in the DRC, said, ‘This time we are seeing not only mass displacement due to violence but also a rapidly spreading measles outbreak and an Ebola epidemic that shows no signs of slowing down, all at the same time.’”

NIPAH and Bats

Like Ebola, NIPAH is zoonotic, and also involves bats, but the viruses differ. CDC explains that, “Nipah virus (NiV) is a member of the family Paramyxoviridae, genus Henipavirus. NiV was initially isolated and identified in 1999 during an outbreak of encephalitis and respiratory illness among pig farmers and people with close contact with pigs in Malaysia and Singapore. Its name originated from Sungai Nipah, a village in the Malaysian Peninsula where pig farmers became ill with encephalitis.

A recent human outbreak in southern India has been followed up with a study of local bats. In a report shared by ProMED, out of 36 Pteropus species bats tested for Nipah, 12 (33%) were found to be positive for anti-Nipah bat IgG antibodies. Unlike Ebola there are currently no experimental drugs or vaccines.

Climate Change and Dengue

Climate change is expected to heighten the threat of many neglected tropical diseases, especially arboviral infections. For example, the New York Times reports that increases in the geographical spread of dengue fever. Annually “there are 100 million cases of dengue infections severe enough to cause symptoms, which may include fever, debilitating joint pain and internal bleeding,” and an estimated 10,000 deaths. Dengue is transmitted by Aedes mosquitoes that also spread Zika and chikungunya. A study, published Monday in the journal Nature Microbiology, found that in a warming world there is a strong likelihood for significant expansion of dengue in the southeastern United States, coastal areas of China and Japan, as well as to inland regions of Australia. “Globally, the study estimated that more than two billion additional people could be at risk for dengue in 2080 compared with 2015 under a warming scenario.”

Schistosomiasis – MDA Is Not Enough, and Neither Are Supplementary Interventions

Schistosomiasis is one of the five neglected tropical diseases (NTDs) that are being controlled and potentially eliminated through mass drug administration (MDA) of preventive chemotherapy (PCT), in this case praziquantel. In The Lancet Knopp et al. reported that biannual MDA substantially reduced Schistosomiasis haematobium prevalence and infection intensity but was insufficient to interrupt transmission in Zanzibar. In addition, neither supplementary snail control or behaviour change activities did not significantly boost the effect of MDA. Most MDA programs focus on school aged children, and so other groups in the community who have regular water contact would not be reached. Water and sanitation activities also have limitations. This raises the question about whether control is acceptable for public health, or if there needs to be a broader intervention to reach elimination?

Trachoma on the Way to Elimination

Speaking of elimination, WHO has announced major “sustained progress” on trachoma efforts. “The number of people at risk of trachoma – the world’s leading infectious cause of blindness – has fallen from 1.5 billion in 2002 to just over 142 million in 2019, a reduction of 91%.” Trachoma is another NTD that uses the MDA strategy.

The news about NTDs from Dengue to Schistosomiasis to Trachoma is complicated and demonstrates that putting diseases together in a category does not result in an easy choice of strategies. Do we control or eliminate or simply manage illness? Can our health systems handle the needs for disease elimination? Is the public ready to get on board?

Malaria Updates

And concerning being complicated, malaria this week again shows many facets of challenges ranging from how to recognize and deal with asymptomatic infection to preventing reintroduction of the disease once elimination has been achieved. Several reports this week showed the particular needs for malaria intervention ranging from high burden areas to low transmission verging on elimination to preventing re-introduction in areas declared free from the disease.

In South West, Nigeria Dokunmu et al. studied 535 individuals aged from 6 months were screened during the epidemiological survey evaluating asymptomatic transmission. Parasite prevalence was determined by histidine-rich protein II rapid detection kit (RDT) in healthy individuals. They found that, “malaria parasites were detected by RDT in 204 (38.1%) individuals. Asymptomatic infection was detected in 117 (57.3%) and symptomatic malaria confirmed in 87 individuals (42.6%).

Overall, detectable malaria by RDT was significantly higher in individuals with symptoms (87 of 197/44.2%), than asymptomatic persons (117 of 338/34.6%)., p = 0.02. In a sub-set of 75 isolates, 18(24%) and 14 (18.6%) individuals had Pfmdr1 86Y and 1246Y mutations. Presence of mutations on Pfmdr1 did not differ by group. It would be useful for future study to look at the effect of interventions such as bednet coverage. While Southwest Nigeria is a high burden area, the problem of asymptomatic malaria will become an even bigger challenge as prevalence reduces and elimination is in sight.

Sri Lanka provides a completely different challenge from high burden areas. There has been no local transmission of malaria in Sri Lanka for 6 years following elimination of the disease in 2012. Karunasena et al. report the first case of introduced vivax malaria in the country by diagnosing malaria based on microscopy and rapid diagnostic tests. “The imported vivax malaria case was detected in a foreign migrant followed by a Plasmodium vivax infection in a Sri Lankan national who visited the residence of the former. The link between the two cases was established by tracing the occurrence of events and by demonstrating genetic identity between the parasite isolates. Effective surveillance was conducted, and a prompt response was mounted by the Anti Malaria Campaign. No further transmission occurred as a result.”

Bangladesh has few but focused areas of malaria transmission and hopes to achieve elimination of local transmission by 2030. A particular group for targeting interventions is the population of slash and burn cultivators in the Rangamati District. Respondents in this area had general knowledge about malaria transmission and modes of prevention and treatment was good according to Saha and the other authors. “However, there were some gaps regarding knowledge about specific aspects of malaria transmission and in particular about the increased risk associated with their occupation. Despite a much-reduced incidence of malaria in the study area, the respondents perceived the disease as life-threatening and knew that it needs rapid attention from a health worker. Moreover, the specific services offered by the local community health workers for malaria diagnosis and treatment were highly appreciated. Finally, the use of insecticide-treated mosquito nets (ITN) was considered as important and this intervention was uniformly stated as the main malaria prevention method.”

Kenya offers some lessons about low transmission areas but also areas where transmission may increase due to climate change. A matched case–control study undertaken in the Western Kenya highlands. Essendi et al. recruited clinical malaria cases from health facilities and matched to asymptomatic individuals from the community who served as controls in order to identify epidemiological risk factors for clinical malaria infection in the highlands of Western Kenya.

“A greater percentage of people in the control group without malaria (64.6%) used insecticide-treated bed nets (ITNs) compared to the families of malaria cases (48.3%). Low income was the most important factor associated with higher malaria infections (adj. OR 4.70). Houses with open eaves was an important malaria risk factor (adj OR 1.72).” Other socio-demographic factors were examined. The authors stress the need to use local malaria epidemiology to more effectively targeted use of malaria control measures.

The key lesson arising from the forgoing studies and news is that disease control needs strong global partnerships but also local community investment and adaptation of strategies to community characteristics and culture.

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.

Decreasing Household Costs of Dengue Prevention at Low-Altitudes in Colombia …

… Redirecting Resources into the Hands of People Who Slap Mosquitoes Everyday.

Class members from the course “Social and Behavioral Foundations of Primary Health Care” at the Johns Hopkins Bloomberg School of Public Health write a policy advocacy blog as part of their assignments. Here we are sharing the blog posted by . read more on this and other SBFPHC blog posts by clicking here

Squito(Photo by James Gathany)

Colombia bears high burdens associated with dengue.  During the 2010 epidemic, disability-adjusted-life-years lost were 1178.93 (per 1 million inhabitants) versus just 88.38 averaged for 2011-2012.  Rodriguez et. al (2016) estimated economic burdens higher than $129.9 million USD each year, with most of the burden at the individual household level (46%, 62%, and 64%) for preventing/controlling mosquitos.

The Colombian Ministry of Health and Social Protection uses the 1,800m elevation mark when allocating money to low-altitude departments for dengue-related expenditures.  This suggests that only half of Colombia’s 47 million residents are at risk for dengue.  However, many people vacation at low altitudes where they risk becoming infected and bringing dengue back home.  If low-altitude residents were better equipped to control mosquitos, then both residents and visitors would be better protected.  Unfortunately, low-altitude residents shoulder a greater financial burden for mosquito prevention than the government.  Rodriquez et al. (2016) reported that almost $85 million USD was the highest household burden (for prevention alone) between 2010 and 2012, while the highest government burden was only $35 million USD (for prevention, awareness campaigns, and control combined).

If the Ministry of Health and Social Protection’s vision of equity-based protection and healthcare resources for all is to come to fruition, more money must flow into prevention and control.  Residents should not have to buy expensive sprays when they already live in poverty.  If Ministry-controlled finances were earmarked for inexpensive yet effective household supplies, such as curtains and water container covers, then less money would be required for treatment.  I advocate for reshuffling some of the dengue-related funds to reflect the prevention priority; increase amounts for household prevention and decrease treatment allocations.

Let’s not make low-altitude residents choose between buying expensive sprays or food to eat.  It’s hard enough already just to slap together supper.