Category Archives: Integrated Vector Management

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.

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.

Agriculture and Promotion of Food Security Can Affect Malaria Transmission

The link between malaria and food security in a global context has been made. The influence of malaria on food security was examined. Now the connection between agriculture practices/food security and malaria is pursued below.

A common complaint with programs that distribute insecticide-treated bednets to prevent malaria is that the nets may be used for other purposes that the intended effort to prevent infected mosquitoes from biting people. All informants interviewed for a study in Western Zambia reported that ITNs are regularly used for fishing and the misuse is widespread. Unsustainable fishing practices, drought and population pressure were mentioned as reasons for fishery decline. The implication was that the use of free ITNs for fishing at least saved the population money in a time of declining fortunes.

A broader review of the ITNs for fishing issue was done through contacting expert witnesses across Africa. Mosquito net fishing (MNF) was found to be a broadly pan-tropical activity, particularly prevalent in sub-Saharan Africa. The authors found that, “Perceived drivers of MNF were closely related to poverty, revealing potentially complex and arguably detrimental livelihood and food security implications.”

The mosquito breeding potential of dams cuts across Africa with the number of dams located in malarious areas projected to increase according to Kibret and colleagues. This is because “The population at risk of malaria around existing dams and associated reservoirs, is estimated to increase from 15 million in 2010 to 21-23 million in the 2020s, 25-26 million in the 2050s and 28-29 million in the 2080s.” In addition, areas with dams but without malaria transmission at present, will likely transition to regions of unstable transmission due to climate change.

Likewise, a study in Ethiopia starts with the assertion that, “Dams are important to ensure food security and promote economic development in sub-Saharan Africa,” and then stresses the importance of understanding the consequences of these projects. The researchers found that “the mean monthly malaria incidence and anopheline larval density was generally higher in the dam villages than in the non-dam villages” in all the three dam settings studied. So while dams can increase agricultural production, the authors concluded that, “the presence of dams intensifies malaria transmission in lowland and midland ecological settings.”

Hydro-agricultural projects include dams and irrigation. Human bait mosquito captures volunteers in hydro-agricultural and river bank sites in Cameroon Akono et al. found that mosquito biting rates were higher in hydro-agricultural sites of less urbanized and urban settings than in natural river banks sites. An additional implication is that urban farming, an important component of food security, may influence mosquito and malaria prevalence.

Stoler and colleagues pursued this question of urban agriculture. The odds of self-reported malaria are significantly higher for women in Accra, Ghana who are living within 1 km of urban agriculture compared with all women living near an irrigation source, the association disappearing beyond this critical distance. Likewise in Kumasi, Afrane et al. learned that “adult and larval mosquito abundance and larval survival were high in the irrigated fields in the irrigated (urban) vegetable farm. This therefore, contributed significantly to adult mosquito populations and hence malaria transmission in the city.”

Even agricultural practices in smaller subsistence farms can foster malaria mosquito breeding. Practices found in southwest Nigeria include collection of pools of water in the farms for soaking cassava tubers, digging of trenches, irrigation of farms, and the presence of fish ponds.

Communities can perceive how agricultural practices may contribute to malaria. In Tanzania a fair number of rural respondents associated growing of rice with malaria. They also noted that the need to sleep on their farms at times meant they could not benefit from the mosquito nets hanging back in their house, some hours walk away. The idea of rice cultivation and malaria was tested in central Kenya. Mwangangi and co-researchers found that, “Rice fields and associated canals were the most productive habitat types,” for malaria mosquito breeding. Overall, Mboera et al. found, “evidence that malaria transmission risk varies even between neighbouring villages and is influenced by agro-ecosystems.”

Although we can establish the two-way link or intersection between malaria and food security, we can see that recommended joint or integrated programming may not always be optimal at various levels from the nation to the community. Greater collaboration between health and agricultural ministries and agencies is needed, supported by national policies that see malaria and food production as part of overall national development goals.

Malaria, Lymphatic Filariasis and Insecticide-treated Nets

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Throughout Africa one of the main vectors that carry Lymphatic Filariasis (LF) is the Anopheles mosquito, which also carries the malaria parasite. The Carter Center has been promoting use of insecticide treated nets (ITNs) for many years as part of its LF control efforts, but others may not have gotten the message.

The global community is targeting LF for elimination in 2020. The primary strategy is mass drug administration annually with ivermectin and albendazole. The plan is that up to seven annual rounds of drug distribution in endemic communities where 90% of population coverage is achieved is necessary to stop LF transmission. The Carter Center explains that distribution of long-lasting insecticidal bed nets (LLINs) protects pregnant women and children who cannot take drug treatment.

The LF strategy often builds on and integrates with onchocerciasis control efforts where these diseases overlap. The community directed treatment with ivermectin (CDTI) model pioneered by the African Program for Onchocerciasis Control  (APOC), wherein communities or villages plan together the distribution process including selecting their own community directed distributors (CDDs). This model has also been used to distribute ITNs.

20160818_100110-1A second component of the LF strategy is morbidity management which focuses on enhanced personal hygiene or cleaning of the parts of the body that experience lymphedema. Another aspect uses surgery to address some of the worst effects, hydrocele.  While this component does not ‘control’ LF, it is a necessary effort to reduce suffering and the negative stigma from the disease.

To judge whether transmission has stopped and elimination has been achieved Transmission Assessment Surveys (TAS) are conducted with rapid diagnostic tests on young children after at least 5 years of MDA in a community.  Specifically WHO recommends an implementation unit must have completed five effective rounds of annual MDA defined as achieving rates of drug coverage exceeding 65% in the total population.

For example the Carter Center in Support of the Nigerian Federal Ministry of Health worked in Plateau and Nasarawa States through community health education, delivery of long lasting insecticide-treated nets (LLINs) and 33 million drug treatments for lymphatic filariasis and river blindness between 2000 and 2011. “In 2012, it was confirmed (through TAS) that lymphatic filariasis transmission had stopped. Post-treatment surveillance is currently underway to assure that the parasite is not reintroduced into the area.”

Another component of the assessment process is yet to be fully realized. That is the testing of mosquitoes for the presence of microfilariae. This indirectly implies an important role in preventing human-vector contact as would be achieved through the use of ITNs as well as indoor residual spray (IRS).

Vector control can benefit more than one disease. Integrated vector management is seen as a key tool to prevent reintroduction of LF in areas where anopheles mosquitoes carry the disease and where ITN campaigns are successful.

Ultimately the key to benefiting from the disease control synergies provided by insecticide-treated nets is an understanding what if any effect nets have on transmission. This poses a challenge in terms of separating it from the effect of MDAs as well as the fact that MDAs are time-limited. As MDAs are still underway in many places it is incumbent on program managers to monitor and evaluate the impact of all activities, treatment and vector control, over the next decade to determine the success of eliminating LF and hopefully malaria, too.

Initial Evidence Of A Reduction In Malaria Incidence Following Indoor Residual Spraying With Actellic 300 Cs In A Setting With Pyrethroid Resistance: Mutasa District, Zimbabwe

Mufaro Kanyangarara and her PhD thesis adviser, Luke Mullany of the Johns Hopkins Bloomberg School of Public Health Department of International Health, have been looking into the challenges of controlling and eventually eliminating malaria in a multi-country context in southern Africa. We are sharing abstracts from her pioneering work including the following which explores indoor residual spraying in Zimbabwe in a District near the Mozambique border.

sprayed and unsprayed wardsIn order to reduce the vector population and interrupt disease transmission, IRS with appropriate insecticides is essential. In response to local vector resistance, the Zimbabwe NMCP with support from PMI began a large-scale IRS campaign with organophosphates in four high transmission districts in Manicaland province – Chimanimani, Mutare, Mutasa and Nyanga. Using HMIS data, the present study reports on the effect of switching from pyretheroids to OP on malaria morbidity in one of the four high transmission districts selected. In the subsequent high transmission season following the switch from pyretheroids to organophosphates, there was evidence of a 43% decline in malaria incidence reported by health facilities from wards in Mutasa District treated with organophosphates, after accounting for possible confounding by environmental variables. Previous research shows that switching to organophospates effectively reduced biting rates and vector densities in areas with pyretheroid resistant strains in Ghana, Benin and Tanzania. Although previous research focused on using entomological data to show the reduction in the vector population following application of Actellic, organophosphates, this study adds to the literature by showing a decline in malaria transmission using health facility surveillance data.

In the present study, there were variations in rainfall and temperature over the study period, and these changes were associated with changes in malaria incidence. The study results also indicated malaria transmission in Mutasa District was driven by rainfall, proximity to second order streams, elevation and temperature. These results concur with previous research, which found that elevation, temperature, and rainfall are positively associated with malaria incidence. After adjustment for climatic variables and seasonality, malaria incidence rates a downward trend following the 2014 IRS campaign and thus supporting the plausible conclusion that switching to organophosphates in this setting contributed to the observed public health benefits. No major political, socio-economic, or health-care changes with the potential to reduce malaria morbidity by almost half occurred in Mutasa District during the study period.

Observed and predicted weekly malaria counts in MutasaTypically data from health facilities only includes data on the number of suspected cases. The HMIS in Zimbabwe is more sophisticated in that it allows reports of confirmed malaria cases. In calculating of incidence rates, the denominator used was the catchment area population size. The reliability of this value has been questioned as this assumes that people will visit the closest health facility/health facility in their catchment area. It is noteworthy to mention that in the present study the main results did not chance after including an offset for catchment area population size. This indicates that in the Zimbabwean context, the reported catchment area population size may be a reliable estimate. The study also underscores the utility of HMIS data in the evaluation of population level interventions. The HMIS has the advantage of providing quality data quickly and easily, with minimal additional investment. Additionally, HMIS reflects the burden of disease on the health system. Results from this study further suggest that passive surveillance data from the HMIS in Zimbabwe was sufficiently sensitive to detect IRS related reduction in malaria morbidity among residents of Mutasa District.

There are several important limitations of this study that should be highlighted. Causal inferences between spraying and improvements in malaria incidence should be made with caution as spraying was not implemented as an intervention in a randomized control trial. However, data from 14 health facilities located in unsprayed wards were included in the analysis to serve as a comparison and help understand any possible changes in malaria morbidity unassociated with the 2014 IRS campaign. Although the univariate model indicated that health facilities in unsprayed wards carried a lower burden of malaria, the multivariable model showed no significant differences between health facilities in sprayed and unsprayed wards prior to the IRS pilot, suggesting that climatic variables included in the model adequately adjusted for differences. However, it should be noted that although the study adjusted for environmental factors, it did not account for other factors like population movement, changes in treatment seeking behaviors, changes in the coverage of ITNs during the study period. The model developed in this analysis assumed that these factors remained constant over the study period. This seems reasonable given that the rural population of Mutasa is relatively stable, with access to health facilities providing malaria diagnosis and treatment. Additionally, although the number of suspected malaria cases was not explicitly model, a descriptive analysis does not indicate changes in diagnostic practice over the study period (data not shown). The HMIS in Zimbabwe has been in place for decades and has previously been used to evaluate the impact of changes in malaria morbidity, construct empirical seasonality maps and describe the spatial and temporal distribution of malaria.

Despite these potential limitations, health surveillance systems provide a feasible and efficient means of collecting longitudinal data on measures of malaria morbidity. The pronounced decline in malaria morbidity observed in this study is evidence supporting the benefit of switching to an insecticide class with a different mode of action in response to pyretheroid resistance. Although the IRS strategy implemented by ZNMCP and PMI was successful, continued entomological monitoring will be necessary. Additionally, with emerging resistance to multiple insecticides, this approach may not be sustainable over time. There is need for the development of novel strategies to manage insecticide resistance.

World Mosquito Day Is Not Just About Malaria

World Mosquito Day Block the BiteOur colleagues at Roll Back Malaria remind is that 20 August is marked annually as World Mosquito Day since doctor Sir Ronald Ross first identified female Anopheles mosquitoes as the vector that transmits malaria between humans. This year, 2015 is the 118th annual observance.

It may seem obvious to state, but while malaria is carried by mosquitoes, not all types of mosquitoes carry malaria. And more specifically our control measures for combating the anopheles mosquitoes that carry malaria are not specifically aimed at aedes or culex. This has not stopped public health workers in the field, and health worker trainees in the classroom from broadcasting messages to the public implying that the control and destruction of any mosquito will prevent malaria.

In terms of health communication, if we convince people that any mosquito carries malaria, but institute measures like long lasting insecticide-treated nets and indoor residual spraying aimed at anopheles mosquitoes, we may lose some credibility as people will still see other types of mosquitoes flying about. And then when people develop another febrile illness from bites of those other mosquitoes, they may not differentiate illness types, but say our interventions do not work.

Old poster on malaria-mosquito presentionThe conflation of all mosquitoes with malaria is seen clearly in the image at the right from a common malaria poster. The dirty gutters may contain culex larvae; the cans and bottles may contain aedes larvae. Obviously none of these mosquito species is good for human health, so can we achieve clarity in health communication about mosquito-borne disease on World Mosquito Day and thereafter?

We often forget that people in the community are quite observant of their environment; sometimes more so the the public health inspectors who try to teach them about ways of preventing malaria by reducing mosquito breeding. Villagers deal with mosquitoes on a daily basis and can distinguish the coloring and posture of the different species.

Instead of telling people what to do, it would be more helpful for public health workers to engage in dialogue with people to learn what they know about different types of mosquitoes and different forms of febrile illness. Maybe by learning first from the people, health workers can then become better teachers about integrated vector management.

PS – maybe we can also educate the mass media to stop putting pictures of Aedes aegypti on their malaria stories!

Moving toward Malaria Elimination through Integrated Vector Control

As malaria control efforts are scaled up and sustained, we expect a drop in prevalence to the point where Ministries of Health may no longer devote a whole operational unit – a National Malaria Control Program – to the disease. This does not mean that malaria programming stops, otherwise countries would experience a resurgence.

Pf_mean_2010_NAMWe can learn from countries like Namibia and Rwanda that are on the frontline of malaria elimination efforts. In Namibia, “The National Vector-borne Disease Control Program (NVDCP) at the Namibia Ministry of Health and Social Services effectively controls the spread of malaria with interventions such as spraying dwellings with insecticides, distributing mosquito nets treated with insecticides, using malaria tests that can give accurate results within 15 minutes, and distributing medicines that kill the parasite.”

The NVDCP falls under the Primary Health Care Services Directorate with its five divisions: Epidemiology; Public and Environmental Health Services; Family Planning; Information, Education and Communication (IEC); Disability Prevention and Rehabilitation. Contrary to what one might think, malaria activities are not lost, but are teaming up with international partners like UCSF Global Health Group’s Malaria Elimination Initiative, the Novartis Foundation for Sustainable Development, the London School of Hygiene and Tropical Medicine, the Clinton Health Access Initiative and the Bill & Melinda Gates Foundation.

In Rwanda we now have the Malaria and Other Parasitic Diseases Division (MOPDD) within the Rwanda Biomedical Center within the Ministry of Health. Major donors like the US Presidents Malaria Initiative are supporting the MOPDD to achieve Rwanda’s national strategic plan of reaching the pre-elimination stage by 2018.

PAMCA logo smEven if a country is still highly malaria endemic, it is important to ensure that integrated vector management is taking place so that in the future the country’s malaria efforts will have a strong ‘home base’ to approach elimination. This is why the opportunity presented by upcoming the Second Pan-African Mosquito Control Association is important.  According to the organizers …

The 2nd Pan African Mosquito Control Association (PAMCA) Conference themed, “Emerging mosquito-borne diseases in sub-Saharan Africa” will be held in Dar-es- Salaam, Tanzania, from 6-8th October 2015. The 2nd Annual PAMCA conference will build on the momentum generated following the successful hosting of the 1st PAMCA Annual Conference in Nairobi, Kenya. The main objective is to bring professionals, students, research institutions and other stakeholders working in mosquito control and mosquito-borne diseases research together under common agenda to discuss the challenges of emerging and re-emerging mosquito-borne diseases across the African continent. The conference will seek to illuminate this subject of emerging mosquito-borne diseases and develop progressive resolutions that will serve as guidelines to tackling this challenge going forward. The conference will also offer a platform for participants to exchange knowledge and ideas on mosquito control, forge new collaborations and strengthen existing ones.

We hope that colleagues will submit abstracts soonest focusing on the various conference themes:

  • Emerging mosquito-borne diseases: new Public Health challenges
  • Mosquito resistance to insecticides and population genetics
  • Translating research into practice: Linking interventions to mosquito behavior
  • Multidisciplinary approaches to tackling mosquito-borne disease
  • Mosquito biology & ecology
  • Impact of climate change on mosquito control

 

Indoor Residual Spraying – not a one-trick pony

Jasson Urbach and Donald Roberts claim that the malaria fight is hurt by flimsy anti-DDT research as they opine in Business Day (South Africa) on 9th May 2014. They are particularly exercised by an article on possible DDT effects on bird egg shells. Despite the controversy sparked by the article, there is no evidence that any individual country nor WHO itself is recommending removal of DDT from the arsenal of chemicals used in indoor residual spraying (IRS) to control malaria.

PMI: http://www.pmi.gov/how-we-work/technical-areas/indoor-residual-spraying

PMI: http://www.pmi.gov/how-we-work/technical-areas/indoor-residual-spraying

There is something about DDT that raises hackles among proponents and detractors. But malaria vector control planners do have choices. WHO recommends 14 insecticides for indoor residual spraying against malaria vectors as seen below in an list updated on 25 October 2013:

  1. DDT
  2. Malathion
  3. Fenitrothion
  4. Pirimiphos-methyl
  5. Pirimiphos-methyl
  6. Bendiocarb
  7. Propoxur
  8. Alpha-cypermethrin
  9. Bifenthrin
  10. Cyfluthrin
  11. Deltamethrin
  12. Deltamethrin
  13. Etofenprox
  14. Lambda-cyhalothrin

Ironically DDT tops the list.  No chemical is 100% safe, so the caveat with any of these chemicals is that, “WHO recommendations on the use of pesticides in public health are valid ONLY if linked to WHO specifications for their quality control. WHO specifications for public health pesticides are available on the Internet.

Interestingly, a bigger concern should be the potential for mosquitoes to develop resistance to any of the above mentioned insecticides.  This is why it is important to avoid putting all our eggs – soft or hard shelled – in one basket. Ideally insecticides should be rotated often to prevent resistance from developing.

Decisions to embark on IRS and choice of insecticides should be based on national and sub-national environmental and epidemiological characteristics, not emotional attachment to any particular product.

Malaria Control and Earth Day: are they compatible?

Clearly no one wants to argue against efforts to curb a deadly disease. The question is whether the approaches to doing so have any negative consequences that can be easily ameliorated.

dscn7103-sm.jpgVector control gets the most attention. One concern is the plastic bagging in which long-lasting insecticide treated nets are packaged. Rwanda, which has outlawed commercial use of plastic bags for shopping, is taking the LLIN packaging seriously.  The photo shows net packaging that has been removed at a health center and stored for later incineration. Clients take their nets home in paper bags and are encouraged to hang them immediately.

Another net concern is disposal of old, used, damaged nets. LLINs do not have under ‘normal’ conditions the 5-year lifespan originally hoped. Plans for proper disposal are not fully developed in most settings, but the massive distribution of nets to achieve universal coverage from about 2009-12 are about to need replacement. It is possible that some of the net misuse reported in the media is actually repurposing of old nets. More information from communities and local health authorities is needed.

Insecticides for indoor residual spraying usually are the first thought that comes to mind concerning environmental impact of malaria control. While arguments primarily focus on DDT, it is important to note that WHO has approved over a dozen different insecticides for IRS.  The problem is not so much the use of chemicals for actual IRS, but the misuse outside approved spraying programs for farms and fish kills. At present IRS is a highly geographically focused activity in most countries, and control of the activities seems to be working for the large part, but even the process of preparing for and cleaning up after a spraying exercise can results in spills and contamination. Guidelines exist, but are they followed?

dscn3829sm.jpgThen we get to the issue of medical waste from rapid diagnostic tests.  Some health centers sharps and waste boxes for short term disposal and as pictured here in Burkina Faso, have incinerators tor final disposal.  Community health worker use of RDTs is usually accompanied by sharps and disposal boxes that can be returned to health centers.  All of this needs careful monitoring.

One must even think about packaging of artemisinin-based combination therapy medicines which are prepackaged by age group. These packets are small and are sent home with patients and care-givers. The paper may be burned or composted, but there are also plastic blisters in the packet. This may not account for much on an individual family basis, but on the community level it may be substantial.

dscn3738-safety-box-sm.jpgReaders may think of other environmental concerns from their own experiences and share success stories for environmental management accompanying malaria control in their countries.  So, as noted, we will not stop malaria control efforts on Earth Day, but at least we can be more conscious of the materials used, whether they can naturally decompose in the environment and thus make some contribution to a healthier planet.

Modeling Malaria – getting a handle on vectors

Models represent reality but the closer they come to reality, they better they are at helping us plan.  A session at the American Society of Tropical Medicine and Hygiene yesterday addressed the modeling process for vector control.

VECNet is developing the capacity to take data from multiple sources to tailor vector populations and behavior to local situations. Such models need to consider vector bionomics/population variables, weather/climate/environment, and effectiveness of deployed vector control strategies.

a-stephensi-map-project-2.jpgModelers encourage us to think beyond existing malaria control strategies and consider a varierty of mosquitoe behaviors beyond direct feeding on humans and immediate resting thereafter. Such understandings can lead us to ask whether new interventions could be directed at other vector bevahiors such as …

  • laying eggs (oviposition)
  • feeding on sugars
  • seeking hosts
  • mating
  • resting generally

In short, we were challenged to look at aspects of vector biology that have been ignored or unknown in the past.

nga_gambiae_ss-sm.pngThe MAP project out of Oxford is also beginning detailed mapping of vectors by region and utlimately my country.  Globally there are 41 dominant vector species, so the work ahead is immense, but some mapping has started with three in a program called Risk Mapper.

The session also included product impact estimation. This should help program planners decide on hypothetical outcomes of investments in different existing interventions and even consider possible outcomes were new interventions developed to address the other aspects of mosquito behavior outlined above – e.g. traps, repellents.

The modeling process requires a lot of data that needs to be updated as control interventions proceed. Such data requires a strong corps of entomologists and health information systems staff that many countries lack.  Hopefully modeling efforts will also include these elements of human resource development.