Non-intervention Zone Research Articles

Spatial variation in red deer density in a transboundary forest ecosystem

Forests in Europe are exposed to increasingly frequent and severe disturbances. The resulting changes in the structure and composition of forests can have profound consequences for the wildlife inhabiting them. Moreover, wildlife populations in Europe are often subjected to differential management regimes as they regularly extend across multiple national and administrative borders. The red deer Cervus elaphus population in the Bohemian Forest Ecosystem, straddling the Czech-German border, has experienced forest disturbances, primarily caused by windfalls and bark beetle Ips typographus outbreaks during the past decades. To adapt local management strategies to the changing environmental conditions and to coordinate them across the international border, reliable estimates of red deer density and abundance are highly sought-after by policymakers, wildlife managers, and stakeholders. Covering a 1081-km2 study area, we conducted a transnational non-invasive DNA sampling study in 2018 that yielded 1578 genotyped DNA samples from 1120 individual red deer. Using spatial capture-recapture models, we estimated total and jurisdiction-specific abundance of red deer throughout the ecosystem and quantified the role of forest disturbance and differential management strategies in shaping spatial heterogeneity in red deer density. We hypothesised that (a) forest disturbances provide favourable habitat conditions (e.g., forage and cover), and (b) contrasting red deer management regimes in different jurisdictions create a differential risk landscape, ultimately shaping density distributions. Overall, we estimated that 2851 red deer (95% Credible Interval = 2609–3119) resided in the study area during the sampling period, with a relatively even overall sex ratio (1406 females, 95% CI = 1229–1612 and 1445 males, 95% CI = 1288–1626). The average red deer density was higher in Czechia (3.5 km−2, 95% CI = 1.2–12.3) compared to Germany (2 km−2, 95% CI = 0.2–11). The effect of forest disturbances on red deer density was context-dependent. Forest disturbances had a positive effect on red deer density at higher elevations and a negative effect at lower elevations, which could be explained by partial migration and its drivers in this population. Density of red deer was generally higher in management units where hunting is prohibited. In addition, we found that sex ratios differed between administrative units and were more balanced in the non-intervention zones. Our results show that the effect of forest disturbances on wild ungulates is modulated by additional factors, such as elevation and ungulate management practices. Overall density patterns and sex ratios suggested strong gradients in density between administrative units. With climate change increasing the severity and frequency of forest disturbances, population-level monitoring and management are becoming increasingly important, especially for wide-ranging species as both wildlife and global change transcend administrative boundaries.

Coupled forest zoning and agricultural intervention yields conflicting outcomes for tropical forest conservation in the Democratic Republic of the Congo (DRC)

Agricultural intensification and forest conservation are often seen as incompatible. Agricultural interventions can help boost food security for poor rural communities but in certain cases can exacerbate deforestation, known as the rebound effect. We tested whether coupling agricultural interventions with participatory forest zoning could improve food security and promote forest conservation in the Democratic Republic of the Congo. Simple agricultural interventions led to a >60% increase in cassava yields and a spill-over effect of improved cassava variety uptake in non-intervention zones. Household surveys conducted at the end of the 8 year project implementation period revealed that households that received agricultural interventions had more favorable attitudes toward forest zoning and conservation. The surveys also showed that farmers in the intervention domain practiced less land-intensive field and fallow management strategies compared to those practiced in the non-intervention domain. However, an 18 year time series analysis of Landsat satellite data revealed that agricultural expansion persisted in areas both with and without intervention assistance, and there is risk of a rebound effect. Approximately 70% of the tree cover loss that occurred outside of the agricultural areas was located within a 3 km buffer zone surrounding the outermost edges of the agricultural areas, which suggested that the majority of tree cover loss was caused by agricultural expansion. Within that 3 km buffer, average annual tree cover loss during the post-intervention period was higher in the intervention domain compared to the non-intervention domain (0.17% yr−1 compared to 0.11% yr−1 respectively, p < 0.001), suggesting risk of a rebound effect. The disconnection between household perceptions of zoning adherence and actual behavior indicates the importance of strengthening governance structures for community-based monitoring and enforcement.

Auto-dissemination strategy for larval control of the insecticide-resistant dengue vector Aedes aegypti in Lao PDR

Background: Dengue is reemerging in Laos and the most important recent outbreak was in 2013, with 44,098 cases. In 2019 (September), 27,904 dengue cases, including 54 deaths, were reported. Larviciding is one of the best options for larval control and in Laos, the organophosphate temephos has been the only larvicide used for vector control for decades. Recent studies showed that Aedes aegypti populations from Vientiane were resistant to this insecticide. In this context of dengue reemergence combined with high rates of urbanization, there was an urgent need to provide the public health authorities with new strategies, including new insecticides. We tested the efficacy of an innovative program using the auto-dissemination technique with the use of the In2Care® trap system in semi-field and large-scale field trials. Methods and materials: The auto-dissemination method using the pupacide insect growth regulator pyriproxyfen, was first investigated on the premises of the Institut Pasteur du Laos with 25 traps. This method was also implemented under large-scale field trials, in 2 dengue hotspots of Vientiane. In total, 600 traps were installed in 2 villages covering 1.2 hectares in each village. Aedes sp. densities were measured weekly with adult/larval traps and monthly with entomological indexes. Two other villages were selected as controls. Results: The small-field trial results showed a significant reduction of larvae and adult Aedes aegypti abundance during the treatment. The one year study in large-field trial has just finished and the results will allow us to test the hypothesis that Aedes densities measured weekly with adult/larval traps and monthly with entomological indexes, can decrease dramatically in the intervention zones vs. non-intervention zones. Conclusion: The results showed that the pyriproxyfen auto-dissemination strategy can represent an effective strategy to reduce mosquito densities in specific and determined areas and may represent a potential tool to be used in combination with other vector control strategies in Laos.

The Impact of Insecticide-treated Bed Nets on Parity and Malaria Sporozoite Infectivity of Anopheles Species in Kamuli District, Uganda

Background: The main objective of treating bed nets with insecticides is to affect the mean longevity of the main vector population, and consequently the vector density and sporozoite rates.&#x0D; Objective: This study aimed at establishing the impact of insecticide-treated bed nets (ITNs) on the longevity and ability to transmit malaria sporozoites by the vector species as an assessment of effectiveness of the ITN intervention in Kamuli district, Uganda.&#x0D; Methods: Indoor human-biting mosquitoes were trapped in three randomly selected houses in two separate nights using battery-operated CDC light traps in both intervention (with ITNs) and non-intervention villages (without ITNs). The female anophelines were dissected and their parity rates and Plasmodium falciparum sporozoite positivity compared between the two zones. A sporozoite Enzyme-Linked Immuno Sorbent Assay, ELISA, was used to detect the presence of P. falciparum sporozoites in the parous vectors in both zones.&#x0D; The parity and P. falciparum sporozoite infectivity were compared between the two zones using the Kruskal-Wallis rank sum test of the R-Statistics software.&#x0D; Results: Out of the 166 Anopheles mosquitoes dissected, 37.3% (19 out of 51) and 53.9% (62 out of 115) were parous in the intervention and non-intervention zones, respectively, indicating that parity of the mosquitoes was higher in the non-intervention (p = 0.005). Infectivity of the vectors in the non-intervention exceeded that in the intervention zone (p = 0.032), with active sporozoite transmission observed before and after bed time in the non-intervention zone.&#x0D; Conclusion: Results showed that ITNs had impacted on the survival and consequently the density of the older malaria vectors, and on their ability to transmit Plasmodium sporozoites. This calls for intensification of use of this effective malaria control strategy, coupled with behavioural change communications strategy to promote correct use, as well as use of other interventions like repellents to provide additional protection especially before and after bed time.

Host-feeding Preference of Anopheles Species under Prolonged Use of Insecticide-treated Bed Nets in Kamuli District, Uganda: Implications for Vector Control

Background: The blood-feeding patterns are crucial in incriminating disease vectors as well as facilitating the design and consolidation of effective vector control interventions in an area. &#x0D; Objective: This study aimed to establish if prolonged use of insecticide-treated bed nets (ITNs) caused a shift in the preferred hosts of the common malaria vectors as the hosts were under the bed net. Such a shift would render ITNs less effective and would probably explain the continued morbidity and mortality due to malaria in the highly endemic Kamuli district.&#x0D; Methods: A total of 3,519 indoor and outdoor human biting female Anopheles gambiae sensu lato and An. funestus mosquitoes were collected from 48 households using human-baited bed net traps. All 187 indoor resting blood-fed anophelines collected were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood meal host identification. Of these, 73 mid guts came from 24 households in villages with a 69% ITNs coverage, while 114 mid guts were from 24 households in non-ITN villages.&#x0D; Results: Blood meal hosts were identified in only 10.96% (n = 8) and 14.91% (n = 17) of the Anopheles blood meals from the intervention and non-intervention zones, respectively. Other blood meals could not be clearly identified. Eight (100%) blood meals in the intervention zone were from humans, while in the non-intervention zone, 15 (88.24%), one (5.88%) and one (5.88%) came from humans, cattle and goat, respectively. These findings demonstrated that the malaria vectors in Kamuli district are anthropophilic, with nearly all the mosquitoes collected from both zones feeding on humans during every blood meal (p = 0.82). This indicated high vector-human contacts, and thus implicating these species as important in the transmission of Plasmodium species and probably other infections.&#x0D; Conclusion: The use of insecticide-treated bed nets is effective for controlling malaria vectors inside houses, evoking universal coverage of houses in the area.

Ungulate management in European national parks: Why a more integrated European policy is needed

1. Primary objectives of national parks usually include both, the protection of natural processes and species conservation. When these objectives conflict, as occurs because of the cascading effects of large mammals (i.e., ungulates and large carnivores) on lower trophic levels, park managers have to decide upon the appropriate management while considering various local circumstances.2. To analyse if ungulate management strategies are in accordance with the objectives defined for protected areas, we assessed the current status of ungulate management across European national parks using the naturalness concept and identified the variables that influence the management.3. We collected data on ungulate management from 209 European national parks in 29 countries by means of a large-scale questionnaire survey. Ungulate management in the parks was compared by creating two naturalness scores. The first score reflects ungulate and large carnivore species compositions, and the second evaluates human intervention on ungulate populations. We then tested whether the two naturalness score categories are influenced by the management objectives, park size, years since establishment, percentage of government-owned land, and human impact on the environment (human influence index) using two generalized additive mixed models.4. In 67.9% of the national parks, wildlife is regulated by culling (40.2%) or hunting (10.5%) or both (17.2%). Artificial feeding occurred in 81.3% of the national parks and only 28.5% of the national parks had a non-intervention zone covering at least 75% of the area. Furthermore, ungulate management differed greatly among the different countries, likely because of differences in hunting traditions and cultural and political backgrounds. Ungulate management was also influenced by park size, human impact on the landscape, and national park objectives, but after removing these variables from the full model the reduced models only showed a small change in the deviance explained. In areas with higher anthropogenic pressure, wildlife diversity tended to be lower and a higher number of domesticated species tended to be present. Human intervention (culling and artificial feeding) was lower in smaller national parks and when park objectives followed those set by the International Union for the Conservation of Nature (IUCN).5. Our study shows that many European national parks do not fulfil the aims of protected area management as set by IUCN guidelines. In contrast to the USA and Canada, Europe currently has no common ungulate management policy within national parks. This lack of a common policy together with differences in species composition, hunting traditions, and cultural or political context has led to differences in ungulate management among European countries. To fulfil the aims and objectives of national parks and to develop ungulate management strategies further, we highlight the importance of creating a more integrated European ungulate management policy to meet the aims of national parks.

Landscape-level spread of beetle infestations from windthrown- and beetle-killed trees in the non-intervention zone of the Tatra National Park, Slovakia (Central Europe)

The European spruce bark beetle (Ips typographus) causes widespread Norway spruce (Picea abies) mortality in European forests. The pattern of landscape-level tree mortality varies over the course of beetle outbreak and by the presence and location of active breeding sites. Increased understanding of rules governing the unmanaged spread of beetle-induced tree mortality over the landscape would help to optimise management control strategies on the borderline between highly valuable protected areas and surrounding managed forests.Our study aimed to quantify the dynamics of standing tree infestation patterns from two infestation sources: windthrow and previous-year beetle infestations. Specifically, we (i) evaluated dispersal distances between the nearest infestation source and new infestations, (ii) quantified size and shape of infestation spots, (iii) modelled an infestation gradient and (iv) probability of new infestation during the incipient, peak and decline phases of beetle outbreak. Based on one- and two-year records of colour-infrared aerial photography, taken between 2005 and 2015, we identified windthrown and beetle-killed trees in the non-intervention zone of Tatra National Park, Slovakia (Central Europe).The size and compactness of infestation spots evolved from small and simple to more extended and complex shapes during beetle epidemics. In total, 40% of infestations were smaller than 100 m2 and 79% smaller than 500 m2. Spot growth dominated over spot initiation, with the mean spot growth extent during peak epidemic (54.8 m). Beetle infestations reached the upper tree line (1605 m a.s.l.). In total, 71% of new infestations emerged within 100 m and 97% within 500 m from an infestations source. Emergence of new infestations varied between infestation sources and phases of beetle outbreak. New beetle infestations emerged near windthrown locations during incipient and peak phases and near source beetle infestations during peak and decline phases following inverse power-law function. We found that the forest within 100 m from the active infestation compared to more distant buffers had the highest risk of infestations. The distance to previous-year infestations should be considered as one of the main factors in determining the risk of subsequent tree mortality, especially if other predictors are absent. If the active wind disturbances or beetle infestations neighbour the border of the unmanaged protected area, the search and sanitation felling of active breeding trees should be concentrated within 500 m from the border of unmanaged protected areas in order to restrain the spread of beetle infestations from nature reserve to surrounding managed forests.

Lifting peripheral fortunes: Upgrading transit improves spatial, income and gender equity in Medellin

New transit development often try to provide low-carbon mobility, and improve accessibility. However, it is often unclear who profits most from new transit developments, whether these transit developments can improve equity, and if yes, in which dimensions. Here we study the change in quality of life, instrumentalised as perceived and measured social capital, socio-economic well-being, and quality of public infrastructure after transit developments in Medellin, Columbia. We make use of a detailed questionnaire of 187 questions from 2009 and 2012, aggregate responses into 14 indicators, and compare changes in quality of life between three transit developments zones (comunas), three non-intervention zones, and between income levels and gender. We find that equity improved overall across geographical zones, income, and gender, even as changes in specific quality of life dimensions varied. Our results demonstrate that well-designed transit interventions and participatory planning processes can make cities not only more climate friendly but also more equal.

Interactions between windthrow, bark beetles and forest management in the Tatra national parks

Natural disturbances such as windthrow and bark beetle Ips typographus L. outbreak often affect protected areas with non-intervention type of management located in close proximity to managed forest stands. This raises concerns about the migration of the beetle outbreak from non-intervention zones to adjacent managed forests. In this study we analyzed the spatiotemporal dynamics of large-scale disturbances by intervention and non-intervention type of management in the Tatra mountains (Central Europe). We collected a time series of Landsat images from 2003 to 2014, and applied maximum likelihood classification to map the extent of forest, windthrow, clear-cuts, beetle outbreak and fire. Our classified maps achieved high overall accuracies: 0.93±0.03⩽OA⩽0.96±0.03. The extent of forest declined over the study period. We found higher rate of beetle induced tree mortality in non-intervention versus intervention zone. Within two growing seasons after the windthrow, beetle infestation occurred in close proximity to uncleared windthrow (<∼250m), which suggest the positive effect of salvage logging (removal of windthrown trees) on lowering the risk of beetle outbreak. The two times higher sum of disturbances in intervention then in non-intervention zone indicated the limited impact of sanitation felling (removal of standing beetle infested trees) to reduce beetle population. However, sanitation felling highly contributed to the decline of the forest cover. Overall, our results document the dynamics of windthrow, bark beetle and clear-cuts by type of management, and limited impact of logging activities in reducing beetle outbreak in neighboring areas with intervention and non-intervention type of management.

Country, cover or protection: what shapes the distribution of red deer and roe deer in the Bohemian Forest Ecosystem?

The Bohemian Forest Ecosystem encompasses various wildlife management systems. Two large, contiguous national parks (one in Germany and one in the Czech Republic) form the centre of the area, are surrounded by private hunting grounds, and hunting regulations in each country differ. Here we aimed at unravelling the influence of management-related and environmental factors on the distribution of red deer (Cervus elaphus) and roe deer (Capreolus capreolus) in this ecosystem. We used the standing crop method based on counts of pellet groups, with point counts every 100 m along 218 randomly distributed transects. Our analysis, which accounted for overdispersion as well as zero inflation and spatial autocorrelation, corroborated the view that both human management and the physical and biological environment drive ungulate distribution in mountainous areas in Central Europe. In contrast to our expectations, protection by national parks was the least important variable for red deer and the third important out of four variables for roe deer; protection negatively influenced roe deer distribution in both parks and positively influenced red deer distribution in Germany. Country was the most influential variable for both red and roe deer, with higher counts of pellet groups in the Czech Republic than in Germany. Elevation, which indicates increasing environmental harshness, was the second most important variable for both species. Forest cover was the least important variable for roe deer and the third important variable for red deer; the relationship for roe deer was positive and linear, and optimal forest cover for red deer was about 70% within a 500 m radius. Our results have direct implications for the future conservation management of deer in protected areas in Central Europe and show in particular that large non-intervention zones may not cause agglomerations of deer that could lead to conflicts along the border of protected, mountainous areas.

Restoration of Central-European mountain Norway spruce forest 15 years after natural and anthropogenic disturbance

Storm events resulting in windthrows, bark beetle (Ips typographus) outbreaks and subsequent forestry operations are the main disturbance agents in European mountain Norway spruce (Picea abies) forests. In the 1990s, a bark beetle outbreak resulted in a large-scale dieback of semi-natural mountain spruce forests in the Šumava National Park, Czech Republic. Two applied management measures enabled long-term monitoring of the effect of natural and anthropogenic disturbance on forest recovery: core zones were left without intervention, and surrounding zones were clear-cut, trees removed, and cleared areas replanted. Research plots were established in three disturbance types: climatically conditioned spruce forest with dead canopy, without intervention (1), with intervention (2), and waterlogged spruce forest partly resistant to bark beetle disturbance without intervention (3). The amount and vertical structure of tree regeneration and vegetation changes have been studied since the beginning of the disturbance in 1997.The main question of the study was whether tree regeneration and herb-layer vegetation differed between naturally developing disturbed forests and clearcuts 15years after the disturbance. The species composition of regeneration in all disturbance types consisted mainly of spruce, with accompanying rowan. The total numbers after 15years since the beginning of the disturbance did not differ significantly among the studied disturbance types, and were sufficient to replace the previous canopy. However, in clearcuts, these numbers were achieved by artificial reforestation, which was applied after initial destruction of natural regeneration due to salvage operations, whereas advance natural regeneration grew successfully under the protection of unmanaged dead canopy. There was a more unified height structure of spruce regeneration in the clearcuts, with significantly higher numbers of saplings taller than 2m compared to unmanaged forests. Due to a less harsh change in site conditions, typical herb species flourished in the non-intervention zones in comparison to the clearcuts. The impact of post-disturbance interventions on herb-layer vegetation was still obvious 15years after the event. Therefore, a non-interventional approach is recommended as the best for restoration of mountain Norway spruce forests affected by large-scale natural disturbances.

An outline of economic impacts of management options for Šumava National Park

This analysis briefly compares the economic impacts of three potential future management scenarios for Sumava National Park (NP) in the Czech Republic: (1) continuation of current management, (2) the adoption of draft Bills that would declassify protected areas and enable developments (e.g. ski lift development) within some of the Park ’ s most valuable habitats for wildlife, and (3) the adoption of proposals to expand the wilderness area in the Park ’ s core with associated tourism opportunities.The proposals in the draft Bills have the potential to generate employment through ski lift development, but much of this activity will use imported labour and/or be short-term (e.g. associated with construction work). The financial viability of this development is uncertain for a number of reasons, including: likely requirements to compensate for damage to protected habitats, reduced future snow cover due to climate change, and competition to attract sufficient visitors to use the ski lift. The economic impacts of the adoption of the draft Bills (and, to a lesser extent, of continuing with current management) would also include negative effects on current nature tourism activity and on its long-term potential to expand. Currently, and certainly if the proposed plans in the draft Bill are adopted, the value of the NP as an area of wilderness and high-quality ecosystems will be reduced. This would weaken one of its key selling points as a tourism and recreation destination. The opportunity for international branding of the national park based on these ecosystems would be diminished. This damage to ecosystems would go against the views of the 75% of the Czech population who agree that it is important to halt the loss of biodiversity because we have a moral obligation to look after nature.Pro-wilderness development offers an alternative scenario. It would allow economic opportunities to be pursued to promote nature-based tourism at new locations and activities around an expanded non-intervention zone, while not undermining the ecological integrity of the NP. The Sumava NP is a unique area which supports a wide variety of habitats and species and has the potential to form one of the largest areas of natural forest and wetland habitat in Central Europe. This tourism offer is in keeping with visitor ’ s preferences (identified in a 2010 survey), and can exploit global growth in ecotourism activity. The best access points to the Sumava NP ’ s wilderness are currently regarded as being “full” in that further increases in visitors would damage the wilderness experience which draws visitors. Therefore, there is perceived to be demand for a larger number of carefully managed access points to a larger wilderness area.To maximise the local economic benefits of this tourism development around the park, appropriate training for the local workforce is required. Local benefits could be enhanced through nature-based tourism development that is spread throughout the communities in and around the park. This would not conflict with the park ’ s wild image that attracts visitors, and this visitor market could grow with support from expanded marketing activity. The potential local economic benefits from the pro-wilderness development option include: maintaining and expanding employment in management of the National Park ’ s habitats, visitor facilities and access points; increased nature-based tourism trade in the villages within and surrounding the Park; increased opportunities to attract financing for local economic development (e.g. training and SME support for nature-based tourism), and for the Park ’ s management, both internationally (e.g. from EU funding sources), and locally (e.g. through fees for visitors using specific facilities); a greater proportion of value-added in the tourism offer being generated within the local community, meaning more income can be retained locally and support greater indirect economic activity, and maintaining forestry employment.Key aspects of this analysis are the way in which tourism potential at the Park is developed, and the extent of logging as a measure to manage bark beetle. Sumava NP borders the Bayerischer Wald NP in Germany, which has developed a successful nature-based tourism industry. This offers a proven model to pursue sustainable economic development under the pro-wilderness development scenario, and a unique opportunity for complementary promotion of the two parks branded as the “Wild Heart of Europe”.More specific predictions of economic and employment impacts will require a full economic study. However, this initial analysis indicates that the pro-wilderness scenario offers a more economically and environmentally sustainable development plan for Sumava NP than either the current situation or the plans proposed in draft Bills. It is recommended that proposals in draft Bills should not be pursued at least until a fuller economic evaluation of options has been undertaken.

The implementation of malaria intermittent preventive trialtreatment with sulphadoxine-pyrimethamine in infants reduced all-cause mortality in the district of Kolokani, Mali: results from a cluster randomized control

BackgroundMalaria intermittent preventive treatment of malaria in infant with sulphadoxine-pyrimethamine (IPTi-SP) reduced the incidence of malaria and anaemia by 30% and 20% respectively. The strategy is now a recommended policy for malaria control. However, there was no published study on the impact of the strategy on mortality. The present study assessed the impact of the implementation of IPTi-SP in health services in Mali on all-cause mortality.MethodsThe 22 health sub-districts of the district of Kolokani were randomized at a 1:1 ratio to either receive IPTi-SP or to serve as a control. The IPTi-SP was implemented for two years starting December 2006. Information on births and deaths through 31 March, 2009 was collected on all children who reached four months of age on 1 December, 2006, likely to be exposed to the intervention in 75 localities randomly selected in each zone.ResultsA total of 5,882 children (2,869 from the intervention zone and 3,013 from the nonintervention zone) who reached four months of age between 1 December, 2006 and 1 December, 2008 were surveyed between the age of four months to the age of 18 months from 1 December, 2006 to 31 March, 2009. In the cohort of four to 18 months of age, the mortality rate per 1,000 children was 2.53 in the intervention zone compared to 3.46 in the nonintervention zone, gender and season adjusted mortality rate ratio (MRR) = 0.73 (95% CI 0.55-0.97, p = 0.029). In the cohort of the four to 12 months of age, mortality rates per 1,000 children were 2.22 in the intervention zone and 3.13 in the non-intervention zone, MRR = 0.71 (95% CI 0.49-1.02, p = 0.064) adjusted for gender and season.ConclusionThe implementation of the IPTi-SP resulted in a substantial reduction in all-cause mortality in children. The results of this study support the adoption and the implementation of IPTi-SP as malaria control strategy.Trial RegistrationClinicalTrials.govNCT00766662

Molecular markers of resistance to sulphadoxine-pyrimethamine one year after implementation of intermittent preventive treatment of malaria in infants in Mali

BackgroundIntermittent preventive treatment in infants (IPTi) with sulphadoxine-pyrimethamine (SP) given during routine vaccinations is efficacious in preventing malaria disease and shows no interaction with the vaccines. However, there is a fear that IPTi may result in a rapid increase of parasite resistance to SP.MethodsTo evaluate the impact of IPTi on SP-resistance point mutations, the 22 health sub-districts in the district of Kolokani, Mali, were randomized in a 1:1 ratio and starting in December 2006, IPTi with SP was implemented in 11 health sub-districts (intervention zone), while the other 11 health sub-districts served as the control (non-intervention zone). Blood smears and blood dots on filter paper were obtained from children aged 0-5 years, randomly selected in each of heath sub-districts during two cross-sectional surveys. The first survey was conducted in May 2007 before the start of the transmission season to collect baseline prevalence of the molecular markers of resistance to SP and the second in December 2007 after the end of the transmission season and one year after implementation of IPTi. A total of 427 and 923 randomly selected blood samples from the first and second surveys respectively were analysed by PCR for dhfr and dhps mutations.ResultsEach of the three dhfr mutations at codons 51, 59 and 108 was present in 35% and 57% of the samples during the two surveys with no significant differences between the two zones. Dhps mutations at codons 437 and 540 were present respectively in about 20% and 1% of the children during the two surveys in both zones at similar proportion. The prevalence of quadruple mutants (triple dhfr-mutants + dhps-437G) associated with in-vivo resistance to SP in Mali after one year implementation of IPTi was also similar between the two zones (11.6% versus 11.2%, p = 0.90) and to those obtained at baseline survey (10.3% versus 8.1%).ConclusionThis study shows no increase in the frequency of molecular markers of SP resistance in areas where IPTi with SP was implemented for one year.