What to Observe on October 12th? Malaria’s Arrival in the Americas

Controversy exists about what historical event should be observed in the USA on 12th October. Ernest Faust explained many years ago that, “there is neither direct nor indirect evidence that the malaria parasites existed on this continent prior to the advent of the European conquerors,” while at the same time in the 16th through 18th Centuries, malaria was common in England, Spain, France, Portugal and other European nations that arrived in the “New World.” Initially, with the first voyage of Columbus the European explorers and settlers brought the disease, primarily Plasmodium vivax, while the slave trade brought P. falciparum.

National Geographic in its May 2007 issue provided the story “Jamestown, The Real Story.” This article reported that, “Colonists carried the plasmodium parasite to Virginia in their blood. Mosquitoes along the Chesapeake were ‘infected’ by the settlers and spread the parasite to other humans.” Thus malaria became one of many imported diseases that decimated the indigenous population. The spread of P. vivax in Jamestown was not surprising since the settlement was “located on marshy ground where mosquitoes flourished during the summer.”

Recent research has shown that the “Analysis of genetic material extracted showed that the American P. falciparum parasite is a close cousin of its African counterpart.” This research has documented two genetic groups in Latin America, related to two distinct slave routes run by the Spanish empire in the North, West Indies, Mexico and Colombia and the Portuguese empire to Brazil. Indigenous and remote rural populations of Bolivia, Colombia, Ecuador, Peru, Venezuela and Brazil remain at risk today.

In the South American continent the  native American population might have brought Melanesian strains of P. vivax before the Europeans arrived, but colonizers brought new strains from both Europe and Africa, as well as P. falciparum. Clearly, human migration has played an important role in malaria parasite dissemination through the Americas.

But back to the North American Continent where the USA is observing the historical implications of 12th October, Mark Blackmore reminds us that, “Anthropological and archeological data provide no indication of mosquito-borne diseases among the indigenous people of North America prior to contact with Europeans and Africans beginning in the fifteenth century” (Wing Beats Volume 25 Winter 2015). The spread of malaria by European colonizers is certainly not something to celebrate today.

Biology and Malaria Eradication: Are there Barriers?

During a press conference prior to the release of the executive summary of 3-year study of trends and future projections for the factors and determinants that underpin malaria by its Strategic Advisory Group on Malaria Eradication (SAGme), WHO outlined some hopeful signs emanating from the SAGme including

  1. Lack of biological barriers to malaria eradication
  2. Recognition of the massive social and economic benefits that would provide a return on investment in eradication, and
  3. Megatrends in the areas of factors such as land use, climate, migration, urbanization that could inhibit malaria transmission

Concerning the first point, the executive summary notes that, “We did not identify biological or environmental barriers to malaria eradication. In addition, our review of models accounting for a variety of global trends in the human and biophysical environment over the next three decades suggest that the world of the future will have much less malaria to contend with.”

The group did agree that, “using current tools, we will still have 11 million cases of malaria in Africa in 2050.” So one wonders whether there are biological barriers or not.

Interestingly the group did identify, “Potential biological threats to malaria eradication include development of insecticide and antimalarial drug resistance, vector population dynamics and altered vector behaviour. For example, Anopheles vectors might adapt to breeding in polluted water, and mosquito vector species newly introduced to Africa, such as Anopheles stephensi, could spread more widely into urban settings.”

This discussion harkens back to an important conceptual article by Bruce Aylward and colleagues that raised the question in the American Journal of Public Health, “When Is a Disease Eradicable?” They outlined three important criteria that had been proposed at two international conferences in 1997 and 1998.

  1. biological and technical feasibility
  2. costs and benefits, and
  3. societal and political considerations

Their further expansion on the biological issues using smallpox as an example is instructive. They noted that not only are humans essential for the life cycle of the organism, but that there was no other reservoir for the causative virus, and the virus could not amplify in the environment. In short, there were no vectors, as in the case of malaria. The relatively recent documentation of transmission of malaria between humans and other primates of different plasmodium species is another biological concern. At this point, Malaysia, for example, is reporting more cases of Plasmodium knowlesi in humans that either P vivax or P falciparum.

Another biological issue identified by Aylward and colleagues was the fact that smallpox had one effective and proven intervention, the vaccine. Application of the vaccine could be targeted using photograph disease recognition cards as the signs were quite specific to the disease. Malaria has several effective interventions, but most strategies emphasize the importance of using a combination of these, and implementation is met with a number of management and logistical challenges. The signs and symptoms of malaria are confused with a number of febrile illnesses.

Finally, two other issues raised concern. Insecticide resistance was recognized in the first malaria eradication effort, and is raising its head again, as pointed out by SAGme. Comparing smallpox and yaws, the challenge of latent or sub-clinical/asymptomatic infection was mentioned. Malaria too, is beleaguered with this problem.

Clearly, we must not lose momentum in the marathon (not a race) to eliminate malaria, but we must, as WHO stressed at the press conference, increase our research and development efforts to strengthen existing tools and develop new once to address the biological and logistical challenges.

Doubling a Cholera Response: Applying a single-dose OCV strategy to outbreak control in South Sudan

As part of the course on Social and Behavioral Foundations in Primary Health Care, Rebecca Huebsch posted in the class blog. We have shared these thoughts below.

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91,000 people die from cholera every year. Cholera is a burden which is carried by some of the poorest and most vulnerable people in the world. This disease, which puts about 1.4 billion people at risk annually, is most predominant in low-income nations. One of these nations is South Sudan. Since its independence in 2011, South Sudan has been plagued by ongoing conflict, displacements, poverty, and disease outbreaks. In South Sudan’s most recent cholera outbreak, there were already 20,000 cases before the outbreak could be brought under control.download

Controlling a cholera outbreak requires a combination of approaches; water and sanitation, hygiene promotion, case management, and reactive vaccination campaigns. The oral cholera vaccine (OCV) revolutionized cholera responses and made it possible protect people from this dangerous disease. OCV campaigns are still incredibly resource intense and traditionally target each person with 2-doses of the vaccine. In places like South Sudan, even reaching these people once is difficult, finding them a second time requires a great deal of motivation, resources, and creativity. In the rainy season, large swaths of South Sudan are flooded and become swamps. This is also the time of year that people are most at risk of cholera. A vaccination campaign requires vaccination teams to literally walk through the swamps for hours, or even days, to reach the affected areas.

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Fortunately, a more streamlined approach is possible, and has even been tested in emergency cholera responses in South Sudan. There is a growing body of evidence that supports a single-dose strategy for OCV campaigns. In settings where cholera is endemic, like South Sudan, a single dose of OCV can be as effective as 2 doses for controlling an outbreak. Adopting this strategy would allow the same amount of vaccine to protect double the amount of people. It would also save on the logistical costs of trying to reach each person twice. While a second dose of cholera vaccine makes sense for routine immunization programs because it provides prolonged coverage, it is costly and limiting to an emergency response. In a cholera outbreak, the State Ministries of Health may look to a single-dose strategy to more efficiently control the outbreak and protect their people.

Recent Surge in Polio Cases in Pakistan Necessitates Urgent Review of Strategy

As part of the course on Social and Behavioral Foundations in Primary Health Care, Muhammad N Asghar posted in the class blog. We have shared these thoughts below.

polio 2Pakistan is one of the three polio endemic countries and recent surge in cases shows that eradication of the disease demands an urgent change in strategy. A look at previous five year cases in Pakistan shows a positive progress in reduction of new polio cases; from 307(2014) to 12(2018), but new cases still appeared in almost every province. The reasons behind this country wide presence of disease can be attributed to internal displacement due to conflicts, weak health systems and operational and resource risks. But the alarming increase in number of new polio cases during 2019 has reversed the whole progress made so far as the number of new cases as of today stands at 53. 32 out of 53 cases are reported from KPK region, which had observed massive internal displacement during last decade but the number of IDPs has decreased from last two years due to stability in the region.

screen-shot-2019-08-18-at-9.26.13-amThis recent surge in polio cases in the the province is mainly due to increase in vaccine refusals due to rumors regarding side effects caused by the vaccine on social media. Official sources reported that after rumors refusals to vaccinate increased by 85% in the province. But high number of cases in other provinces when compared with last year cases indicate that multiple factors are hindering the progress towards containment and eradication of the polio virus disease from the country, which can be attributed to homelessness and poor sanitation, operational issues for vaccine delivery, conflicts, cross border movement etc.

This situation demands urgent review of existing strategy for polio eradication as number of new cases are increasing rapidly. There is a need to work on multiple aspects to make the anti-polio drive successful; some key aspects include detailed geo-mapping of the population at basic level and identification of missed areas to ensure every child is vaccinated, involving community and religious leaders, NGOs, CSOs for confidence building and education of the community, expansion of partnership with nutrition, hygiene, water sectors, and robust rebuttal of rumors and strict action against those involved in such heinous activities etc. There is a new political government of helm, which is sensitive to the social sector issues and taking measures to provide homes, health facilities and education to the disadvantaged sections. International agencies (GPEI, WHO) shall coordinate with the political government to review the existing strategy for revamping it, so that not only the current surge can be contained but the disease can be eradicated from the country to achieve the target of polio free world.

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Ebola Crisis Takes a Turn: Increased US Intervention Necessary

As part of the course on Social and Behavioral Foundations in Primary Health Care, Allan Ciciriello posted in the class blog. We have shared his thoughts below.

Confirmed and probable Ebola virus disease cases by week of illness onset by Kivu region health zone. Data as of 13 August 2019

Historically, the 2018 – 2019 Ebola outbreak is the biggest the Democratic Republic of the Congo has ever seen. As a whole, it is also the second largest documented epidemic of the disease on record. The epicenter of the eruption is located in the Kivu region, which has also been in the midst of a conflict between the Congolese military and rebel groups, which has prevented necessary assistance from making its way into the country. Due to the decline of the situation over the past year, culminating with a confirmed case of Ebola in the capital city of Goma, the World Health Organization officially announced it as a Public Health Emergency of International Concern in July 2019.

The spread of the virus to bordering countries is a matter of great importance in the global health community. This includes the nations of Burundi, Rwanda, South Sudan, and Uganda. Given that Goma is a major transportation hub connecting these territories together, it is imperative that the transmission of Ebola be stopped quickly in the Kivu region.

Ebola virus disease in the Democratic Republic of the Congo – Operational readiness and preparedness in neighbouring countries
Recently, the World Health Organization has claimed the current funding is not enough to sustain response activities on a multi-national scale. The United States, who played a large role in the 2014 – 2015 outbreak of Ebola, has had limited participation this time around. This is largely due to the ability of the global health community to respond more adequately to the disease through large improvements in technical capabilities. Security factors with the military conflict have also prevented the United States from getting on the ground in the Democratic Republic of the Congo. However, due to recent changes in the situation, the Congolese government and the World Health Organization cannot efficiently resolve the epidemic without additional help from UN partners, most notably the United States.
‘We won’t get to zero cases of Ebola without a big scale-up in funding,’ UN relief chief warns

The United States must change its current policies on intervening in the Democratic Republic of the Congo Ebola outbreak. Most important is contributing additional funding to sustain the World Health Organization’s role in halting the spread of the virus within the current borders, while also supporting the surrounding nations’ prevention efforts. USAID is a critical source of backing in this ongoing battle, and without them it is likely to falter. I would also reconsider the hesitancy of placing United States government personnel on the frontlines, because as the problem gets more dire the harder it will be to act from within the country. The CDC is another key player in this game, and I would advise the US take advantage of the United Nations Organization Stabilization Mission in the Democratic Republic of the Condo’s (also known as MONUSCO) peacekeeping forces to get public health workers back on the frontline with guaranteed protection from rebel militias.

Tropical Health Update 2019-08-04: Ebola, Malaria Vectors, Snakebite and Trachoma

In the past week urban transmission in Goma, a city of at least 2 million inhabitants in eastern Democratic republic of Congo, was documented as a gold miner came home and infected his wife and child. To get a grip on the spread of the disease, DRC is considering another vaccine, not without some controversy. WHO provides detailed guidance on all aspects of response. On the malaria front we have learned more about malaria vectors, natural immunity and reactive case detection.

Ebola Challenges: Vaccines, Urban Transmission

The current Ebola vaccine being deployed to over 150,000 people in North Kivu and Ituri Provinces was itself an experimental intervention during 2016 when it was first used in the largest ever outbreak located in West Africa. BBC reports that, “World Health Organization (WHO) data show the Merck vaccine has a 97.5% efficacy rate for those who are immunised, compared to those who are not.”

The proposed addition of a Johnson and Johnson vaccine would be in that same experimental phase if introduced in DRC now. It has been proven safe as well as effective in other primates. The challenge is that even though the Merck vaccine supplies are near 500,000, this is not enough to cover the potential needs in an area with over 10 million people, although Merck is still producing more. At present, BBC says, “Those pushing for the use of the new Johnson & Johnson vaccine, had proposed using it to create a protective wall, vaccinating people outside the outbreak zone.” In addition, the new national response team is concerned that “Only about 50% of cases of Ebola in the Democratic Republic of Congo are being identified.”

Finally, there is the issue of community mistrust of government workers and challenging logistics. “There are also concerns that the new vaccine – which requires two injections 56 days apart – may be difficult to administer in a region where the population is highly mobile, and insecurity is rife.”

If efforts at vaccination are needed soon in Goma, up to 2 million doses might be needed. Reuters reports that, “Congolese authorities were racing to contain an Ebola epidemic on Thursday, after a gold miner with a large family contaminated several people in the east’s main city of Goma before dying of the hemorrhagic fever.” Readers may recall that the West Africa outbreak of 2014-16 in Guinea, Sierra Leone and Liberia accelerated greatly after infected people went to major cities in search of help.

The miner is the second ‘imported case into Goma, which borders Rwanda, but because his family lives there, he has already infected his wife and one of his 10 children. Contacts are being traced and monitored, but this urban and border threat is one of the factors that led WHO to finally declare the current outbreak a public health emergency.

Malaria

As we move toward malaria elimination Reactive Case Detection (RCD) has been proposed as an integral part of these efforts with the hopes that is can be conceived of as a way of gradually decreasing transmission, according to an article in Malaria Journal. In fact, the value of RCD may be limited as follows:

  • RCD alone can eliminate malaria in only a very limited range of settings, where transmission potential is very low
  • In other settings, it is likely to reduce disease burden and help maintain the disease-free state in the face of imported infections

Another article looks at “natural exposure to gametocytes that can result in the development of immunity against the gametocyte by the host as well as genetic diversity in the gametocyte.” The researchers learned that there can be variations in immune response depending on season and geography. This information is helpful in planning malaria elimination interventions.

On the vector front a baseline susceptibility testing was conducted in 16 countries in sub-Saharan Africa for neonicotinoids. “The target site of neonicotinoids represents a novel mode of action for vector control, meaning that cross-resistance through existing mechanisms is less likely.” The findings will help in the preparation for rollout of clothianidin formulations as part of national IRS rotation strategies by PMI and other partners.

Researchers also called on us to learn more about malaria vectors in other parts of the world. In order to eliminate Plasmodium falciparum from the Caribbean and Central America program planners should consider local vector characteristics such as An. albimanus. They found that, “House-screening and repellent IRS are potentially highly effective against An. albimanus if people are indoors during the evening.”

Vectors are also of concern on the edges of malaria transmission, particularly in South Africa, one of the ‘elimination eight’ countries of the Southern Africa Development Community. Researchers examined the, “potential role of Anopheles parensis and other Anopheles species in residual malaria transmission, using sentinel surveillance sites in the uMkhanyakude District of northern KwaZulu-Natal Province.” They found Anopheles parensis is a potential but minimal vector of malaria in South Africa “owing to its strong zoophilic tendency.” On the other hand, An. arabiensis was found to be the major vector responsible for residual malaria transmission in South Africa. Since these mosquitoes were found in outdoor-placed resting traps, interventions are needed to control outdoor-resting of vector populations.

NTDs of Concern

During the week, the member states of the African Union renewed their commitment to fight and permanently eliminate Neglected Tropical Diseases. Africa.com reported that, “Achievements to date include 1 billion people treated against at least one NTD and 37 countries have completed the removal of at least one NTD.”

Although some reports have discounted the idea of trachoma in Namibia, there may be reason to re-examine the situation. On Twitter Anthony Solomon notes that Namibia needs #trachoma prevalence surveys. A just-completed joint Ministry of Health & Social Services/@WHO mission found active trachoma & trichiasis in Zambezi & Kunene Regions.

The Times of India draws attention to snakebite. It says that “Under-reported and inadequately treated, fatalities in India are estimated at close to 50,000 a year, the world’s highest.”

Overall we can see that the concept of ‘neglect’ has several uses. There is neglect if half of Ebola cases are undetected. There is neglect if we do not understand malaria vectors in low transmission areas. Finally, there is neglect if we do not conduct up-to-date disease surveys to determine whether a disease is present or not. Elimination of tropical diseases is challenging when key processes are neglected.

Tropical Health Update 2019-07-28: Ebola and Malaria Crises

This posting focuses on Malaria and Ebola, both of which have been the recent focus of some disturbing news. The malaria community has been disturbed by the clear documentation of resistance to drugs in Southeast Asia. Those working to contain Ebola in the northeast of the Democratic Republic of Congo saw a change in political leadership even in light of continued violence and potential cross-border spread.

Malaria Drug Resistance

Several sources reported on studies in the Lancet Infectious Diseases concerning the spread of Multidrug-Resistant Malaria in Southeast Asia. Reuters explained that by sing genomic surveillance, researchers concurred that “strains of malaria resistant to two key anti-malarial medicines are becoming more dominant” and “spread aggressively, replacing local malaria parasites,” becoming the dominant strains in Vietnam, Laos and northeastern Thailand.”

The focus was on “the first-line treatment for malaria in many parts of Asia in the last decade has been a combination of dihydroartemisinin and piperaquine, also known as DHA-PPQ,” and resistance had begun to spread in Cambodia between 2007 and 2013. Authors of the study noted that while, “”Other drugs may be effective at the moment, but the situation is extremely fragile, and this study highlights that urgent action is needed.” They further warned of an 9impending Global Health Emergency.

NPR notes that “Malaria drugs are failing at an “alarming” rate in Southeast Asia” and provided some historical context about malaria drug resistance arising in this region since the middle of the 20th century. “Somehow antimalarial drug resistance always starts in that part of the world,” says Arjen Dondorp, who leads malaria research at the Mahidol Oxford Tropical Medicine Research Unit in Bangkok and who was a lead author of the report about the randomized trial. Ironically, “one reason could have something to do with the relatively low levels of malaria there. When resistant parasites emerge, they are not competing against a dominant nonresistant strain of malaria and are possibly able to spread easier.

When we are talking about monitoring resistance in low resource and logistically and politically challenging areas, we need to think of appropriate diagnostic tools at the molecular level. Researchers in Guinea-Bissau conducted a proof of concept study and used malaria rapid diagnostic tests applied for parallel sequencing for surveillance of molecular markers. While they noted that, “Factors such as RDT storage prior to DNA extraction and parasitaemia of the infection are likely to have an effect on whether or not parasite DNA can be successfully analysed … obtaining the necessary data from used RDTs, despite suboptimal output, becomes a feasible, affordable and hence a justifiable method.”

A Look at Insecticide Treated Nets

On a positive note, Voice of America provides more details on the insecticide treated net (ITN) monitoring tool developed called “SmartNet” by Dr Krezanoski in collaboration with the Consortium for Affordable Medical Technologies in Uganda. The net uses strips of conductive fabric to detect when it’s in use. Dr. Krezanoski was happy to find that people given the net used it no differently that if they were not being observed. The test nets made it clear who what using and not using this valuable health investment and when it was in use. Such fine tuning will be deployed to design interventions to educate net users based on their real-life use patterns.

Another important net issue is local beliefs that may influence use. We can find out when people use nets, but we also need to determine why. In Tanzania, researchers found that people think mosquitoes that bite in the early evening when people are outside relaxing are harmless. As one community member said, “I only fear those that bite after midnight. We’ve always been told that malaria is spread by mosquitoes that bite after midnight.”

Even if people do use their ITNs correctly, we still need to worry about insecticide resistance. A study in Afghanistan reported that, “Resistance to different groups of insecticides in the field populations of An. stephensi from Kunar, Laghman and Nangarhar Provinces of Afghanistan is caused by a range of metabolic and site insensitivity mechanisms.” The authors conclude that vector control programs need to be better prepared to implement insecticide resistance management strategies.

Ebola Crisis Becomes (More) Political

Headlines such as “Congo health minister resigns over response to Ebola crisis” confronted the global health community this week. this happened after the DRC’s relatively new president took control of the response. The President set up a new government office to oversee the response to an outbreak outside of the Ministry of Health which was managing the current outbreak and the previous ones. The new board was set up without the knowledge of the Minister who was traveling to the effected provinces at the time.

The former Minister, Dr Oly Ilunga stated on Twitter that, “Suite à la décision de la @Presidence_RDC.  de gérer à son niveau l’épidémie d’#Ebola, j’ai remis ma démission en tant que Ministre de la Santé ce lundi. Ce fut un honneur de pouvoir mettre mon expertise au service de notre Nation pendant ces 2 années importantes de notre Histoire. (Following the decision of the @Presidence_RDC to manage the # Ebola outbreak, I resigned as Minister of Health on Monday. It was an honor to be able to put my expertise at the service of our Nation during these two important years of our History.)

The former Minister also warned that the “Multisectoral Ebola Response Committee would interfere with the ongoing activities of national and international health workers on the ground in North Kivu and Ituri provinces.” Part of the issue may likely have been “pressure to approve a new vaccine in addition to one that has already been used to protect more than 171,000 people.” People had warned about the potential confusion to the public as well as ethical issues if a second vaccine was used, especially one that did not have the strong accumulated evidence from both the current outbreak as well as the previous one in West Africa.

One might have thought that this would be a time when stability was needed since “The WHO earlier this month declared the outbreak a Public Health Emergency of International Concern, a rare step meant to highlight the urgency of the moment that has been used only four times before.” In addition, “the World Bank said it would release $300 million from a special fund set aside for crises like viral outbreaks to help cover the cost of the response.”

Unfortunately one of the msain impediments to successful Ebola control, violence in the region, continues. CIDRAP stated that. “the Allied Democratic Forces (ADF), a rebel group, attacked two villages near Beni, killing 12 people who live in the heart of the Democratic Republic of the Congo’s (DRC’s) ongoing Ebola outbreak. The terrorists killed nine in Eringeti and three in Oicha, according to Reuters. ADF has not publicly pledged allegiance to the Islamic state (ISIL), but that hasn’t stopped ISIL from claiming responsibility for the attacks.” It will take more than a change of structure in Kinshasa to deal with the realities on the ground.

CIDRAP also observed that since the resignation of the Health Minister, “DRC officials have provided no update on the outbreak, including statistics on the number of deaths, health workers infected, or suspected cases.” The last was seen on 21 July 2019.

ReliefWeb reports that, “Adding to the peril, the Ebola-affected provinces share borders with Rwanda and Uganda, with frequent cross-border movement for personal travel and trade, increasing the chance that the virus could spread beyond the DRC. There have already been isolated cases of Ebola reported outside of the outbreak zone.”

These are troubling times when parasites and mosquitoes are becoming more resistant to our interventions and when governments and communities are resistant to a clear and stable path to disease containment and control.

The Weekly Tropical Health News 2019-07-13

In the past week more attention was drawn to the apparently never-ending year-long Ebola outbreak in the northeast of the Democratic Republic of the Congo. Regarding other diseases, there is new information on the RTS,S malaria vaccine, river prawns have been found to play a biological control role in schistosomiasis, and an update from the World Health Organization on essential medicines and diagnostics. New malaria vector control technologies are discussed.

Second Largest Ebola Outbreak One Year On

Ronald A. Klain and Daniel Lucey in the Washington Post observed raised concern that, “the disease has since crossed one border (into Uganda) and continues to spread. In the absence of a trajectory toward extinguishing the outbreak, the opposite path — severe escalation — remains possible. The risk of the disease moving into nearby Goma, Congo — a city of 1 million residents with an international airport.”

They added their voices to a growing number of experts who are watching this second biggest Ebola outbreak in history and note that, “As the case count approaches 2,500 with no end in sight, it is time for the WHO to declare the outbreak a public health emergency of international concern — a ‘PHEIC’ — to raise the level of global alarm and signal to nations, particularly the United States, that they must ramp up their response.” They call for three actions: 1) improved security for health workers in the region, 2) stepped up community engagement and 3) extended health care beyond Ebola treatment. The inability to adequately respond to malaria, diarrheal diseases and maternal health not only threated life directly, but also threated community trust, putting health workers’ lives at risk.

Olivia Acland, a freelance journalist based in DRC, reporting for the New Humanitarian describes the insecurity and the recent “wave of militia attacks in the Democratic Republic of Congo’s northeastern Ituri province has left hundreds dead and roughly 300,000 displaced in recent weeks, triggering a new humanitarian crisis in a region.” Specifically, “Ituri, a fertile region rich in gold deposits, has been an epicentre of conflict in Congo for decades. Between 1999 and 2003, around 60,000 people were killed here, as a power struggle between rebel groups escalated into ethnic violence,” related to traditional tensions between Hema cattle herders and Lendu farmers with roots in Belgian colonization.

Updates from the DRC Ministry of Health report on average 11 new Ebola cases per day in the past week. So far over 160,000 people have been vaccinated, and yet the spread continues. The Ministry also describes new protocol contains three vaccinations strategies that can be used depending on the environment in which confirmed cases are found including:

  • Classic Ring: The classic strategy of vaccinating contacts of confirmed cases and contact contacts.
  • Enlarged ring: It is also possible to vaccinate all inhabitants of houses within 5 meters around the outbreak of a confirmed case.
  • Geographical Ring: In an area where team safety can not be guaranteed, they can vaccinate an entire village or neighborhood.

Malaria Vaccines, Essential Drugs and New Vector Control Technologies

Halidou Tinto and colleagues enrolled two age groups of children in a 3-year extension of the RTS,S/AS01 vaccine efficacy trial: 1739 older children (aged 5–7 years) and 1345 younger children (aged 3–5 years). During extension, they reported 66 severe malaria cases. Overall they found that, “severe malaria incidence was low in all groups, with no evidence of rebound in RTS,S/AS01 recipients, despite an increased incidence of clinical malaria in older children who received RTS,S/AS01 compared with the comparator group in Nanoro. No safety signal was identified,” as seen in The Lancet.

WHO has updated the global guidance on medicines and diagnostic tests to address health challenges, prioritize highly effective therapeutics, and improve affordable access. Section 6.5.3 presents antimalarial medicines including curative treatment (14 medicines) for both vivax and falciparum and including tablets and injectables. Prophylaxis includes 6 medicines including those for IPTp and SMC. The latest guidance can be downloaded at WHO.

Paul Krezanoski reports on a new technology to monitor bednet use and tried it out in Ugandan households. As a result. “Remote bednet use monitors can provide novel insights into how bednets are used in practice, helping identify both households at risk of malaria due to poor adherence and also potentially novel targets for improving malaria prevention.

In another novel technological approach to vector control, Humphrey Mazigo and co-researchers tested malaria mosquito control in rice paddy farms using biolarvicide mixed with fertilizer in Tanzanian semi-field experiments. The intervention sections (with biolarvicide) had lowest mean mosquito larvae abundance compared to control block and did not affect the rice production/harvest.

Prawns to the Rescue in Senegal Fighting Schistosomiasis and Poverty

Anne Gulland reported how Christopher M. Hoover et al. discovered how prawns could be the key to fighting poverty and schistosomiasis, a debilitating tropical disease. They found that farming the African river prawn could fight the disease and improve the lives of local people, because the African river prawn is a ‘voracious’ predator of the freshwater snail, which is a carrier of schistosomiasis.

The researchers in Senegal said that, “market analysis in Senegal had shown there was significant interest among restaurant owners and farmers in introducing prawns to the diet.” The prawn could also for the basis of aquaculture in rice paddies and remove the threat of schistosomiasis from the rice workers.

—- Thank you for reading this week’s summary. These weekly abstractings have replaced our occasional mailings on tropical health issues due to fees introduced by those maintaining the listserve website. Also continue to check the Tropical Health Twitter feed, which you can see running on this page.

The Weekly Tropical Health News 2019-07-06: Eliminating Malaria in Low Transmission Settings

This week started with articles that drew attention to the challenges of malaria in low transmission areas and with low density infections. Malaria Journal has provided several insightful articles toward this end.

Being an island has certainly helped Zanzibar make progress toward malaria elimination as witness the fact that malaria prevalence has remained below 1% for the past decade. Not only does Zanzibar still face threats of infection from the mainland, it may also experience an upsurge locally if residual transmission and the role of human behavior and community actions are not well understood. April Monroe et al. conducted in-depth interviews with community members and local leaders across six sites on Unguja, Zanzibar as well as semi-structured community observations of night-time activities and special events to learn more.

While there was high reported ITN use, there were also times when people were exposed t mosquitoes while being outdoors during biting times. This could be around the house, or at special night events like such as weddings, funerals, and religious ceremonies. Men spent more time outdoors than women. Clearly appropriate interventions and needed and should be promoted in culturally appropriate ways in order to further reduce and eventually eliminate transmission.

Angela Early and colleagues presented findings on a diagnostic process of deep sequencing for understanding the dynamics and complexity of Plasmodium infections, but stress that knowing the lower limit of detection is challenging. They present “a new amplicon analysis tool, the Parallel Amplicon Sequencing Error Correction (PASEC) pipeline, is used to evaluate the performance of amplicon sequencing on low-density Plasmodium DNA samples.”

The authors learned that, “four state-of-the-art tools resolved known haplotype mixtures with similar sensitivity and precision.” They also cautioned that, “Samples with very low parasitemia and very low read count have higher false positive rates and call for read count thresholds that are higher than current default recommendations.” Better understanding of the genetic mix of plasmodium infections as countries move toward low transmission and elimination is crucial for selecting appropriate interventions and evaluating their outcomes.

Hannah Edwards and co-researchers examined conditions for malaria transmission along the Thailand-Myanmar border in areas approaching malaria elimination. While prevalence may be less than 1%, residual transmission still occurs. Transmission occurs not only around residences but in the forests where people work. The researchers therefore looked at the behavior of both humans and insects. Overall, they found that, “Community members frequently stayed overnight at subsistence farm huts or in the forest. Entomological collections showed higher biting rates of primary vectors in forested farm hut sites and in a more forested village setting compared to a village with clustered housing and better infrastructure.”

While mosquitoes preferred to bite inside huts, their threat was magnified by those who did not use long lasting insecticide-treated nets (LLINs). While out in the farms and forests, people tended to wake early and increase their likelihood of being bitten. The authors discuss the challenges of dual residences in terms of LLIN ownership and even concerning the potential access to indoor residual spraying. The definition for universal net coverage needs to expand from one net per two people to include adequate nets wherever people are located.

The Amazonian area of Brazil is another area working toward malaria elimination, in particular, Plasmodium vivax. Felipe Leão Gomes Murta et al. also looked at the human side of the equation and identified misperceptions by both community members and health workers that could inhibit elimination efforts. They found, “many myths regarding malaria transmission and treatment that may hinder the sensitization of the population of this region in relation to the use of current control tools and elimination strategies, such as mass drug administration (MDA),” and LLINs.

Problematic perceptions included mention by both groups that the use of insecticide-treated nets, may cause skin irritations and allergies. Both community members and health professionals said malaria is “an impossible disease to eliminate because it is intrinsically associated with forest landscapes.” They concluded that such perceptions can be a barrier to control and elimination.

Efforts to eliminate malaria from low transmission settings are an essential to the overall global goals. These four articles tell us that close attention to and better understanding of humans, parasites and mosquitoes is still needed to achieve these goals.

Nigeria’s 2018 Demographic and Health Survey: Malaria Situation

The Demographic and Health Survey for 2018 in Nigeria has released preliminary findings. These cover insecticide Treated Nets (ITNs), Intermittent Preventive Treatment of malaria in pregnancy (IPTp), and treatment of children with Artemisinin-Based Combination Therapy (ACT).

The key findings have been converted into graphs.  We can see that ITN ownership by a household (HH) is greater in rural areas, but overall reaches only a national average of 60% of households having at least one net. People may recall that the 2010 target by the Roll Back malaria Partnership was 80% for all key indicators with the hope that by attaining and then maintaining 80% coverage or more, malaria incidence would drop and elimination would be on the horizon.

Nigeria is not among WHO’s Elimination by 2020 (E2020) countries, and it is not clear when transmission will move in that direction when key interventions are still not reaching targets. This is due also to the fact that 60% of households covered does not mean that residents are protected. In fact only 30% meet the goal of universal net coverage with at least one net for every two household members.

On the positive side, comparison of household net ownership and wealth status appears to favor the poorer households. 72% of the poorest households have at least one net compared to 48% of the highest income quintile.  Unfortunately the gap between rich and poor narrows when it comes to the target of 1 net for 2 people.

Although these days we stress universal coverage of all household members, DHS still collects data on what are often termed ‘vulnerable’ groups, children below the age of 5 years and pregnant women.  Just over half of each group slept under an ITN the night before the survey. It is obvious that access plays a role, so in those households that actually own at least one net 74% of children and 82% of pregnant women slept under an ITN. These figures might even be higher if the target of 1 net per two people were met.

Nigeria is a huge and diverse country in terms of geography, epidemiology and ethncity. The country has 6 regions that are used for planning and analysis purposes. The map attached shows that there are major regional variations in households owning at least one net and households having at least one net for every 2 people residing there.

There is better coverage of at least one net per household in the northern zones than the southern, with the Northwest achieving 86% and then 42% for covering two people with one net.  When it comes to that latter measure, the remaining 5 regions are all in the 20% level, meaning that for most of the country, there is a long way to go to achieve universal net coverage.

Intermittent preventive treatment of pregnant women  with sulphadoxine-pyrimethamine (SP) has been a long standing intervention to protect women and their unborn children from the devastating effects of malaria. For at least six years now, WHO has recommended that pregnant women take three or more monthly doses of IPTp from the 13th week of pregnancy, onward.

A challenge to getting IPTp is contact with antenatal care services, and only 67% of women who delivered a child in the 5 year preceding the survey attended ANC even once.  Not surprisingly, only 40% of those pregnant women received two doses of IPTp and only 17% got three doses.

Finally, only 28% of children with fever in the two weeks prior to the survey took ACT, although we are not certain about the proportion who had been tested. It is difficult to interpret this finding since we do not know what proportion of those with fever might have been tested and found to harbor malaria parasites. ACTs should only be given to those with positive parasitological tests.

DHS and its sister survey, the Malaria Indicator Survey are performed at approximately three-year intervals. These data sources are valuable for evaluating past interventions and planning new. Clearly some serious planning is needed to address the shortfalls in malaria intervention coverage and save more lives.