BackgroundAn intensive effort to control malaria in Zimbabwe has produced dramatic reductions in the burden of the disease over the past 13 years. The successes have prompted the Zimbabwe’s National Malaria Control Programme to commit to elimination of malaria. It is critical to analyse the changes in the morbidity trends based on surveillance data, and scrutinize reorientation to strategies for elimination.MethodsThis is a retrospective study of available Ministry of Health surveillance data and programme reports, mostly from 2003 to 2015. Malaria epidemiological data were drawn from the National Health Information System database. Data on available resources, malaria control strategies, morbidity and mortality trends were analysed, and opportunities for Zimbabwe malaria elimination agenda was perused.ResultsWith strong government commitment and partner support, the financial gap for malaria programming shrank by 91.4% from about US$13 million in 2012 to US$1 million in 2015. Vector control comprises indoor residual house spraying (IRS) and long-lasting insecticidal nets, and spray coverage increased from 28% in 2003 to 95% in 2015. Population protected by IRS increased also from 20 to 96% for the same period. In 2009, diagnostics improved from clinical to parasitological confirmation either by rapid diagnostic tests or microscopy. Artemisinin-based combination therapy was used to treat malaria following chloroquine resistance in 2000, and sulfadoxine–pyrimethamine in 2004. In 2003, there were 155 malaria cases per 1000 populations reported from all health facilities throughout the country. The following decade witnessed a substantial decline in cases to only 22 per 1000 populations in 2012. A resurgence was reported in 2013 (29/1000) and 2014 (39/1000), thereafter morbidity declined to 29 cases per 1000 populations, only to the same level as in 2013. Overall, morbidity declined by 81% from 2003 to 2015. Inpatient malaria deaths per 100,000 populations doubled in 4 years, from 2/100,000 to 4/100,000 populations in 2012–2015 respectively. Twenty of the 47 moderate to high burdened districts were upgraded from control to malaria pre-elimination between 2012 and 2015.ConclusionsA significant progress to reduce malaria transmission in Zimbabwe has been made. While a great potential and opportunities to eliminate malaria in the country exist, elimination is not a business as usual approach. Instead, it needs an improved, systematic and new programmatic strategy supported strongly by political will, sustained funding, good leadership, community engagement, and a strong monitoring and evaluation system all year round until the cessation of local transmission.

Understanding the demographic history and genetic make-up of colonizing species is critical for inferring population sources and colonization routes. This is of main interest for designing accurate control measures in areas newly colonized by vector species of economically important pathogens. The biting midge Culicoides imicola is a major vector of orbiviruses to livestock. Historically, the distribution of this species was limited to the Afrotropical region. Entomological surveys first revealed the presence of C. imicola in the south of the Mediterranean basin by the 1970s. Following recurrent reports of massive bluetongue outbreaks since the 1990s, the presence of the species was confirmed in northern areas. In this study, we addressed the chronology and processes of C. imicola colonization in the Mediterranean basin. We characterized the genetic structure of its populations across Mediterranean and African regions using both mitochondrial and nuclear markers, and combined phylogeographical analyses with population genetics and approximate Bayesian computation. We found a west/east genetic differentiation between populations, occurring both within Africa and within the Mediterranean basin. We demonstrated that three of these groups had experienced demographic expansions in the Pleistocene, probably because of climate changes during this period. Finally, we showed that C. imicola could have colonized the Mediterranean basin in the Late Pleistocene or Early Holocene through a single event of introduction; however, we cannot exclude the hypothesis involving two routes of colonization. Thus, the recent bluetongue outbreaks are not linked to C. imicola colonization event, but rather to biological changes in the vector or the virus.

The study was aimed at determining the seasonal abundance of Xenopsylla brasiliensis, an important vector of plague in Zimbabwe, from rodent hosts captured in selected habitat types of two periurban suburbs of Harare, Zimbabwe. The removal-trapping method was used to capture the rodents, from which fleas were collected and identified. Percentage incidence index (PII) and specific flea index (SFI) were calculated for X. brasiliensis in relation to rodent species host. Mastomys natalensis, Rattus rattus, Tatera leucogaster, and Rhabdomys pumilio were the rodent species present in the study areas and all species were infested with X. brasiliensis. PII for T. leucogaster in relation to X. brasiliensis was significantly higher (p < 0.05) compared with that of the other rodent species and T. leucogaster also recorded the highest SFI, whereas R. pumilio recorded the lowest indices. In both formal and informal settlements, the highest PII of X. brasiliensis was attained for M. natalensis, followed by R. rattus. In the cultivated habitat, T. leucogaster recorded the highest indices and R. pumilio the lowest. X. brasiliensis was found to cohabitat with Dinopsyllus lypusus and Ctenophthalmus calceatus on M. natalensis, R. rattus, and T. leucogaster. No cohabitation was recorded for R. pumilio. For all the rodent species captured, both the PII and SFI of X. brasiliensis were highest during the hot-dry season, followed by the hot-wet season, with the cold-dry season recording the lowest indices. The overall cohabitation was highest during the hot-dry season and lowest during the hot-wet season. The findings of the present study fit the reported occurrence of plague outbreaks during the hot-dry season in periurban Zimbabwe.

BackgroundInsecticide resistance in major malaria vectors poses severe challenges for stakeholders responsible for controlling the disease. During the 2013/14 season, malaria vector sentinel sites in Mutare and Mutasa Districts, Zimbabwe, experienced high presence of gravid malaria vector mosquitoes resting indoors in recently pyrethroid-sprayed structures. Subsequently, an evaluation of insecticide resistance in Anopheles funestus populations, the major malaria vector, was conducted to better inform the Zimbabwe National Malaria Control Programme.MethodsIndoor-resting mosquitoes were collected in randomly selected pyrethroid-sprayed houses around Burma Valley and Zindi sentinel sites in Mutare and Mutasa Districts, respectively, using prokopac aspirator in February 2014. A. funestus mosquitoes were identified in the field using morphological keys and divided into two cohorts. One cohort was used immediately for WHO susceptibility tests and the other batch was transferred to the National Institute of Health Research insectary in Harare for oviposition. Susceptibility and intensity resistance assays were carried out on polymerase chain reaction-assayed, 3–5 days old, A. funestus s.s. F1 progeny females.ResultsEight-hundred and thirty-six A. funestus and seven Anopheles gambiae complex mosquitoes were collected resting inside living structures. Wild caught females showed resistance to lambda-cyhalothrin (3.3 % mortality), deltamethrin (12.9 % mortality), etofenprox (9.2 % mortality), and bendiocarb (11.7 % mortality). F1 A. funestus female progeny indicated resistance to deltamethrin (14.5 % mortality), lambda-cyhalothrin (6.9 % mortality), etofenprox (8.3 % mortality), and bendiocarb (16.8 % mortality). Wild caught and female progeny were susceptible to DDT and pirimiphos-methyl (100 % mortality). Intensity resistance assay to bendiocarb was 100 % mortality, while deltamethrin, lambda-cyhalothrin, and etofenprox had increased knockdown times with mortalities ranging between 66.7 and 92.7 % after 24-h exposures.ConclusionThis study is the first report of pyrethroid and carbamate resistance in A. funestus populations from Burma Valley and Zindi areas and indicates a major threat to the gains made in malaria vector control in Zimbabwe. In view of the current extension and intensity of such resistance, there is urgent need to set up a periodic and systematic insecticide resistance-monitoring programme which will form the basis for guiding the selection of insecticides for indoor residual spraying and distribution of pyrethroid-treated mosquito nets.

This review outlines and discusses the new challenges in malaria control and prospects for its elimination in Mutare and Mutasa Districts, Zimbabwe. The burden of malaria has declined significantly over the past 5 years in most regions in Zimbabwe, including Mutare and Mutasa Districts. The nationwide malaria reduction has been primarily linked to scaled-up vector control interventions and early diagnosis and treatment with effective anti-malarial medicines. The successes recorded have prompted Zimbabwe’s National Malaria Control Programme to commit to a global health agenda of eliminating malaria in all districts in the country. However, despite the decline in malaria burden in Mutare and Mutasa Districts, there is clear evidence of new challenges, including changes in vector behaviour, resistance to insecticides and anti-malarial medicines, invasion of new areas by vectors, vectors in various combination of sympatry, changes in vector proportions, outdoor malaria transmission, climate change and lack of meticulousness of spray operators. These new challenges are likely to retard the shift from malaria control to elimination in Mutare and Mutasa Districts.

Plague is a zoonotic disease caused by the bacterium Yersinia pestis and is transmitted through the bites of infected rodent fleas. Plague is well known for causing 3 major human pandemics that have killed millions of people since 541 A.D. The aim of this Review is to provide an overview of the epidemiology and ecology of plague in Zimbabwe with special emphasis on its introduction, its potential reservoirs and vectors, and possible causes of its persistence and cyclic outbreaks. To achieve this, we carried out a search and document reported plague outbreaks in Zimbabwe. In the country, human plague cases have been reported in Hwange, Nkayi, and Lupane since 1974. The highest number of cases occurred in 1994 in the Nkayi district of Matabeleland North Province with a total of 329 confirmed human cases and 28 deaths. Plague is encountered in 2 different foci in the country, sylvatic and rural. Risk factors for contracting plague in the country include man-to-rodent contact, cultivation, hunting, cattle herding, handling of infected materials, camping in forests, and anthropic invasion of new areas. Plague is now enzootic in Zimbabwe, and the most recent case was reported in 2012, hence its effective control requires up-to-date information on the epidemiology and ecology of the disease. This can be achieved through continuous monitoring and awareness programs in plague-prone areas.

Regular entomological monitoring is important to determine changes in mosquito species composition and relative densities of malaria vectors in relation to vector control interventions. A study to gain insights into malaria vector species composition and relative abundance was undertaken in Mutare and Mutasa districts,

BackgroundTsetse (Glossina sensu stricto) are cyclical vectors of human and animal trypanosomoses, that are presently targeted by the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) coordinated by the African Union. In order to achieve effective control of tsetse, there is need to produce elaborate plans to guide intervention programmes. A model intended to aid in the planning of intervention programmes and assist a fuller understanding of tsetse distribution was applied, in a pilot study in the Masoka area, Mid-Zambezi valley in Zimbabwe, and targeting two savannah species, Glossina morsitans morsitans and Glossina pallidipes.Methodology/Principal findingsThe field study was conducted between March and December 2015 in 105 sites following a standardized grid sampling frame. Presence data were used to study habitat suitability of both species based on climatic and environmental data derived from MODIS and SPOT 5 satellite images. Factors influencing distribution were studied using an Ecological Niche Factor Analysis (ENFA) whilst habitat suitability was predicted using a Maximum Entropy (MaxEnt) model at a spatial resolution of 250 m. Area Under the Curve (AUC), an indicator of model performance, was 0.89 for G. m. morsitans and 0.96 for G. pallidipes. We then used the predicted suitable areas to calculate the probability that flies were really absent from the grid cells where they were not captured during the study based on a probability model using a risk threshold of 0.05. Apart from grid cells where G. m. morsitans and G. pallidipes were captured, there was a high probability of presence in an additional 128 km2 and 144 km2 respectively.Conclusions/SignificanceThe modelling process promised to be useful in optimizing the outputs of presence/absence surveys, allowing the definition of tsetse infested areas with improved accuracy. The methodology proposed here can be extended to all the tsetse infested parts of Zimbabwe and may also be useful for other PATTEC national initiatives in other African countries.