Updates on malaria epidemiology and profile in Cabo Verde from 2010 to 2019: the goal of elimination.

BACKGROUND: Located in West Africa, Cabo Verde is an archipelago consisting of nine inhabited islands. Malaria has been endemic since the settlement of the islands during the sixteenth century and is poised to achieve malaria elimination in January 2021. The aim of this research is to characterize the trends in malaria cases from 2010 to 2019 in Cabo Verde as the country transitions from endemic transmission to elimination and prevention of reintroduction phases. METHODS: All confirmed malaria cases reported to the Ministry of Health between 2010 and 2019 were extracted from the passive malaria surveillance system. Individual-level data available included age, gender, municipality of residence, and the self-reported countries visited if travelled within the past 30 days, therby classified as imported. Trends in reported cases were visualized and multivariable logistic regression used to assess risk factors associated with a malaria case being imported and differences over time. RESULTS: A total of 814 incident malaria cases were reported in the country between 2010 and 2019, the majority of which were Plasmodium falciparum. Overall, prior to 2017, when the epidemic occurred, 58.1% (95% CI 53.6-64.6) of infections were classified as imported, whereas during the post-epidemic period, 93.3% (95% CI 86.9-99.7) were imported. The last locally acquired case was reported in January 2018. Imported malaria cases were more likely to be 25-40 years old (AOR: 15.1, 95% CI 5.9-39.2) compared to those under 15 years of age and more likely during the post-epidemic period (AOR: 56.1; 95% CI 13.9-225.5) and most likely to be reported on Sao Vicente Island (AOR = 4256.9, 95% CI = 260-6.9e+4) compared to Boavista. CONCLUSIONS: Cabo Verde has made substantial gains in reducing malaria burden in the country over the past decade and are poised to achieve elimination in 2021. However, the high mobility between the islands and continental Africa, where malaria is still highly endemic, means there is a constant risk of malaria reintroduction. Characterization of imported cases provides useful insight for programme and enables better evidence-based decision-making to ensure malaria elimination can be sustained

Indoor residual spraying for malaria control in sub-Saharan Africa 1997 to 2017: an adjusted retrospective analysis

Indoor residual spraying (IRS) is a key tool for controlling and eliminating malaria by targeting vectors. To support the development of effective intervention strategies it is important to understand the impact of vector control tools on malaria incidence and on the spread of insecticide resistance. In 2006, the World Health Organization (WHO) stated that countries should report on coverage and impact of IRS, yet IRS coverage data are still sparse and unspecific. Here, the subnational coverage of IRS across sub‑Saharan Africa for the four main insecticide classes from 1997 to 2017 were estimated

Strengthening adult mosquito surveillance in Africa for disease control: Learning from the present

Mosquito surveillance is essential to successfully control and eliminate mosquito-borne diseases. Yet, it is often done by numerous organizations with little collaboration, incomplete understanding of existing gaps, and limited long-term vision. There is a clear disconnect between entomological and epidemiological indices, with entomological data informing control efforts inadequately. Here we discuss current mosquito surveillance practises across the heterogenous disease landscape in Africa. We advocate for the development of mosquito surveillance strategic plans to increase the impact and functionality of mosquito surveillance. We urge for a proactive approach to set up centralized mosquito data systems under custodian of national governments, focus on epidemiologically relevant mosquito data and increase robustness of mosquito surveillance using a more spatially explicit sampling design

Factors related to human-vector contact that modify the likelihood of malaria transmission during a contained Plasmodium falciparum outbreak in Praia, Cabo Verde

Background: Determining the reproductive rate and how it varies over time and space (RT) provides important insight to understand transmission of a given disease and inform optimal strategies for controlling or eliminating it. Estimating RT for malaria is difficult partly due to the widespread use of interventions and immunity to disease masking incident infections. A malaria outbreak in Praia, Cabo Verde in 2017 provided a unique opportunity to estimate RT directly, providing a proxy for the intensity of vector-human contact and measure the impact of vector control measures. Methods: Out of 442 confirmed malaria cases reported in 2017 in Praia, 321 (73%) were geolocated and informed this analysis. RT was calculated using the joint likelihood of transmission between two cases, based on the time (serial interval) and physical distance (spatial interval) between them. Log-linear regression was used to estimate factors associated with changes in RT, including the impact of vector control interventions. A geostatistical model was developed to highlight areas receptive to transmission where vector control activities could be focused in future to prevent or interrupt transmission. Results: The RT from individual cases ranged between 0 and 11 with a median serial- and spatial-interval of 34 days [interquartile range (IQR): 17–52] and 1,347 m (IQR: 832–1,985 m), respectively. The number of households receiving indoor residual spraying (IRS) 4 weeks prior was associated with a reduction in RT by 0.84 [95% confidence interval (CI) 0.80–0.89; p-value <0.001] in the peak-and post-epidemic compared to the pre-epidemic period. Conclusions: Identifying the effect of reduced human-vector contact through IRS is essential to determining optimal intervention strategies that modify the likelihood of malaria transmission and can inform optimal intervention strategies to accelerate time to elimination. The distance within which two cases are plausibly linked is important for the potential scale of any reactive interventions as well as classifying infections as imported or introduced and confirming malaria elimination

Achievement of malaria pre-elimination in Cape Verde according to the data collected from 2010 to 2016

Abstract Background Malaria, despite being preventable and treatable, continues to be a major public health problem worldwide. The archipelago nation of Cape Verde is in a malaria pre-elimination phase with the highest potential to achieve the target goal of elimination in 2020. Methods Nationwide malaria epidemiological data were obtained from the Cape Verde health information system that includes the individual malaria case notification system from all of the country’s health structures. Each case is reported to the surveillance service then to the National Malaria Control Programme, which allowed for compilation in the national malaria case database. The database was analysed to assess the origin of the malaria cases, and incidence was calculated from 2010 to 2016 by sex and age. The health centre, health district and month of diagnosis were evaluated, as well as the sex and the age of the patients, allowing a direct descriptive analysis of national data to provide an up-to-date malaria epidemiological profile of the country. Malaria cases were classified as imported or indigenous, and then, geographical analyses were performed using a unique Geographical National Code with Quantum Geographic Information System 2.16.2 software to map the cases by municipalities. The overall temporal evolution of cases was analysed to assess their monthly and yearly variations from 2010 to 2016. Results Malaria is unstable in Cape Verde, with inter-annual variation and the majority of infections occurring in adult males (> 20 years). The indigenous cases are restricted to Santiago (96%) and Boavista (4%), while imported cases were recorded in all the nine inhabited islands, originating from neighbouring countries with ongoing malaria transmission; from Lusophone countries (25% from Angola, 25% from Guinea-Bissau), followed by the Republic of Senegal (12%) and Equatorial Guinea (10%). In 2010–2012, more imported (93 cases) than indigenous cases (26 cases) were observed; conversely, in 2013 and 2014, more indigenous cases (49) than imported cases (42) were reported. In 2015 there were 20 imported cases and only 7 indigenous cases. Finally, in 2016, there were 47 indigenous cases and 28 imported cases. The mapping of cases by municipality and country of origin was possible with GIS analyses. Conclusion While Cape Verde remains on track to achieve malaria elimination by 2020 owing to the reduction of the annual incidence to below 0.1%, the country still records cases of indigenous and imported malaria. However, the indigenous cases are exclusively confined to the Santiago and Boavista islands, while the imported cases recorded nationwide originate only from the African continent, mainly from adult men from the Lusophone countries. Cape Verde needs to target interventions to remove residual foci on Santiago and Boavista islands to reduce malaria lethality to zero and prevent its reintroduction from African countries via transmission across the archipelago. Cape Verde is a good example of local authority’s commitment to tackle malaria and work towards its elimination by strengthening the health and surveillance systems

Spatiotemporal characterisation and risk factor analysis of malaria outbreak in Cabo Verde in 2017

Abstract Background Cabo Verde is a country that has been in the pre-elimination stage of malaria since the year 2000. The country is still reporting cases, particularly in the capital of Praia, where more than 50% of the national population live. This study aims to examine the spatial and temporal epidemiological profile of malaria across the country during the 2017 outbreak and to analyse the risk factors, which may have influenced the trend in malaria cases. Methods Longitudinal data collected from all malaria cases in Cabo Verde for the year 2017 were used in this study. The epidemiological characteristics of the cases were analysed. Local and spatial clusters of malaria from Praia were detected by applying the Cluster and Outlier Analysis (Anselin Local Moran’s I) to determine the spatial clustering pattern. We then used the Pearson correlation coefficient to analyse the relationship between malaria cases and meteorological variables to identify underlying drivers. Results In 2017, 446 cases of malaria were reported in Cabo Verde with the peak of cases in October. These cases were primarily Plasmodium falciparum infections. Of these cases, 423 were indigenous infections recorded in Praia, while 23 were imported malaria cases from different African countries. One case of P. vivax infection was imported from Brazil. Spatial autocorrelation analysis revealed a cluster of high-high malaria cases in the centre of the city. Malaria case occurrence has a very weak correlation (r = 0.16) with breeding site location. Most of the cases (69.9%, R 2 = 0.699) were explained by the local environmental condition, with temperature being the primary risk factor followed by relative humidity. A moderately positive relationship was noted with the total pluviometry, while wind speed had a strong negative influence on malaria infections. Conclusions In Cabo Verde, malaria remains a serious public health issue, especially in Praia. The high number of cases recorded in 2017 demonstrates the fragility of the situation and the challenges to eliminating indigenous malaria cases and preventing imported cases. Mosquito breeding sites have been the main risk factor, while temperature and precipitation were positively associated with malaria infection. In light of this study, there is an urgent need to reinforce control strategies to achieve the elimination goal in the country

The prevalence of glucose-6-phosphate dehydrogenase deficiency in the Cape Verdean population in the context of malaria elimination.

Cabo Verde aims to eliminate malaria by 2020. In the country, Plasmodium falciparum had been the main parasite responsible for indigenous cases and primaquine is the first line treatment of cases and for radical cure. However, the lack of knowledge of the national prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency may be one of the constraints to the malaria elimination process. Hence, this first study determines the prevalence of G6PD deficiency (G6PDd) in the archipelago. Blood samples were collected from patients who voluntarily agreed to participate in the study, in the health facilities of eight municipalities on four islands, tested with G6PD CareStart ™ deficiency Rapid Diagnosis Test (RDT). All subjects found to be G6PDd by RDT then underwent enzyme quantification by spectrophotometry. Descriptive statistics and inferences were done using SPSS 22.0 software. A total of 5.062 blood samples were collected, in majority from female patients (78.0%) and in Praia (35.6%). The RDT revealed the prevalence of G6PD deficiency in 2.5% (125/5062) of the general population, being higher in males (5.6%) than in females (1,6%). The highest G6PDd prevalence was recorded in São Filipe, Fogo, (5.4%), while in Boavista no case was detected. The G6PDd activity quantification shown a higher number of partially deficient and deficient males (respectively n = 26 and n = 22) compared to females (respectively n = 18 and n = 7), but more normal females (n = 35) than males (n = 11). According to the WHO classification, most of the G6PDd cases belongs to the class V (34.5%), while the Classes II and I were the less represented with respectively 5.8% and zero cases. This study in Cabo Verde determined the G6PDd prevalence in the population, relatively low compared to other African countries. Further studies are needed to characterize and genotyping the G6PD variants in the country

Knowledge, attitudes and practices about malaria in Cabo Verde: a country in the pre-elimination context

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