bims-mosdis Biomed News
on Mosquito distribution and disease
Issue of 2022–08–28
seventeen papers selected by
Richard Halfpenny, Staffordshire University



  1. Front Microbiol. 2022 ;13 947857
      Wolbachia, an intracellular maternally transmitted endosymbiont, has been shown to interfere with the replication of dengue virus in Aedes aegypti mosquitoes. The Wolbachia-transinfected Ae. aegypti has been currently released in many countries to test its effectiveness in preventing the transmission of dengue virus. ICMR-Vector Control Research Centre in collaboration with World Mosquito Program Monash University, Australia, has generated two new Wolbachia-introgressed Ae. aegypti Puducherry (Pud) lines via backcrossing Ae. aegypti females of Australian (Aus) strains, infected with wMel and wAlbB Wolbachia with wild-type Ae. aegypti Puducherry (Pud) males. Wolbachia infections are known to induce a fitness cost and confer benefit on the host mosquito populations that will influence spread of the Wolbachia into native wild mosquito populations during the field release. Hence, the induced fitness cost or benefit/advantage in the two newly generated Ae. aegypti (Pud) lines was assessed in the laboratory in comparison with the wild-type Ae. aegypti (Pud) strain. In addition, maternal transmission (MT) efficiency, induced cytoplasmic incompatibility (CI), and insecticide resistance status of the two (Pud) lines were determined to assess the likely frequency of wMel and wAlbB infections in the native wild population after field invasion. The study shows that wMel and wAlbB infections did not induce any fitness cost on the two newly generated (Pud) lines. Rather, in terms of wing length, fecundity, egg hatch rate, and adult survival, the Wolbachia introgression conferred fitness benefits on the (Pud) lines compared to uninfected Wolbachia free wild Ae. aegypti population. wMel and wAlbB exhibited a high maternal transmission (99-100%) and induced nearly complete (98-100%) cytoplasmic incompatibility. Both the (Pud) lines were resistant to deltamethrin, malathion, DDT, and temephos, and the level of resistance was almost the same between the two lines as in the wild type. Overall, the stable association of wMel and wAlbB established with Ae. aegypti and the reproductive advantages of the (Pud) lines encourage a pilot release in the field for population replacement potential.
    Keywords:  Aedes aegypti; Wolbachia; dengue; fitness cost; wAlbB; wMel
    DOI:  https://doi.org/10.3389/fmicb.2022.947857
  2. Curr Res Insect Sci. 2021 ;1 100001
      Aedes (Stegomyia) albopictus (Skuse) is a major global invasive mosquito species that, in Japan, co-occurs with Aedes (Stegomyia) flavopictus Yamada, a closely related species recently intercepted in Europe. Here, we present results of a detailed 25-month long study where we biweekly sampled pupae and fourth instar larvae of these two species from ovitraps set along Mt. Konpira, Nagasaki, Japan. This setting allowed us to ask whether these species had different responses to changes in environmental variables along the altitudinal gradient of an urban hill. We found that spatially Ae. albopictus abundance decreased, while Ae. flavopictus abundance increased, the further away from urban land. Ae. flavopictus also was more abundant than Ae. albopictus in locations with homogenous vegetation growth with a high mean Enhanced Vegetation Index (EVI), platykurtic EVI, and low SD in canopy cover, while Ae. albopictus was more abundant than Ae. flavopictus in areas with more variable (high SD) canopy cover. Moreover, Ae. flavopictus abundance negatively impacted the spatial abundance of Ae. albopictus. Temporally we found that Ae. flavopictus was more likely to be present in Mt. Konpira at lower temperatures than Ae. albopictus. Our results suggest that spatial and temporal abundance patterns of these two mosquito species are partially driven by their different response to environmental factors.
    Keywords:  Environmental gradients; Invasive species; NDVI and EVI; Schmalhausen`s law; Zero inflated count models
    DOI:  https://doi.org/10.1016/j.cris.2020.100001
  3. Rev Soc Bras Med Trop. 2022 ;pii: S0037-86822022000100621. [Epub ahead of print]55 e0427
       BACKGROUND: Arthropod-borne viruses have recently emerged and are pathogens of various human diseases, including dengue, zika, and chikungunya viruses.
    METHODS: We collectedAedes aegyptilarvae (N = 20) from Brumado, Bahia, Brazil, and treated and individually preserved the specimens. We analyzed the samples for dengue, zika, and chikungunya viruses using molecular biology methods.
    RESULTS: We found that 25% (N = 5) and 15% (N = 3) were positive exclusively for dengue and chikungunya viruses, respectively; 15% (N = 3) were coinfected with both.
    CONCLUSIONS: This is the first report of dengue and chikungunya virus coinfection in A. aegypti larvae.
    DOI:  https://doi.org/10.1590/0037-8682-0427-2021
  4. Biology (Basel). 2022 Aug 03. pii: 1166. [Epub ahead of print]11(8):
      Culex quinquefasciatus, one of the most significant mosquito vectors in the world, is widespread in most parts of southern China. A variety of diseases including Bancroft's filariasis, West Nile disease, and St. Louis encephalitis could be transmitted by the vector. Mosquitoes have been shown to host diverse bacterial communities that vary depending on environmental factors such as temperature and rainfall. In this work, 16S rDNA sequencing was used to analyze the seasonal variation of midgut bacterial diversity of Cx. Quinquefasciatus in Haikou City, Hainan Province, China. Proteobacteria was the dominant phylum, accounting for 79.7% (autumn), 73% (winter), 80.4% (spring), and 84.5% (summer). The abundance of Bacteroidetes in autumn and winter was higher than in others. Interestingly, Epsilonbacteraeota, which only exists in autumn and winter, was discovered accidentally in the midgut. We speculated that this might participate in the nutritional supply of adult mosquitoes when temperatures drop. Wolbachia is the most abundant in autumn, accounting for 31.6% of bacteria. The content of Pantoea was highest in the summer group, which might be related to the enhancement of the ability of mosquitoes as temperatures increased. Pseudomonas is carried out as the highest level in winter. On the contrary, in spring and summer, the genus in highest abundance is Enterobacter. Acinetobacter enriches in the spring when it turns from cold to hot. By studying the diversity of midgut bacteria of Cx. quinquefasciatus, we can further understand the co-evolution of mosquitoes and their symbiotic microbes. This is necessary to discuss the seasonal variation of microorganisms and ultimately provide a new perspective for the control of Cx. quinquefasciatus to reduce the spread of the diseases which have notably vital practical significance for the effective prevention of Cx. quinquefasciatus.
    Keywords:  16S rDNA; Culex quinquefasciatus; diversity of midgut bacteria; environmental factors
    DOI:  https://doi.org/10.3390/biology11081166
  5. PLoS Negl Trop Dis. 2022 Aug 23. 16(8): e0010334
       BACKGROUND: Colombia has one of the highest burdens of arboviruses in South America. The country was in a state of hyperendemicity between 2014 and 2016, with co-circulation of several Aedes-borne viruses, including a syndemic of dengue, chikungunya, and Zika in 2015.
    METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the cases of dengue, chikungunya, and Zika notified in Colombia from January 2014 to December 2018 by municipality and week. The trajectory and velocity of spread was studied using trend surface analysis, and spatio-temporal high-risk clusters for each disease in separate and for the three diseases simultaneously (multivariate) were identified using Kulldorff's scan statistics. During the study period, there were 366,628, 77,345 and 74,793 cases of dengue, chikungunya, and Zika, respectively, in Colombia. The spread patterns for chikungunya and Zika were similar, although Zika's spread was accelerated. Both chikungunya and Zika mainly spread from the regions on the Atlantic coast and the south-west to the rest of the country. We identified 21, 16, and 13 spatio-temporal clusters of dengue, chikungunya and Zika, respectively, and, from the multivariate analysis, 20 spatio-temporal clusters, among which 7 were simultaneous for the three diseases. For all disease-specific analyses and the multivariate analysis, the most-likely cluster was identified in the south-western region of Colombia, including the Valle del Cauca department.
    CONCLUSIONS/SIGNIFICANCE: The results further our understanding of emerging Aedes-borne diseases in Colombia by providing useful evidence on their potential site of entry and spread trajectory within the country, and identifying spatio-temporal disease-specific and multivariate high-risk clusters of dengue, chikungunya, and Zika, information that can be used to target interventions.
    DOI:  https://doi.org/10.1371/journal.pntd.0010334
  6. Pathogens. 2022 Aug 20. pii: 945. [Epub ahead of print]11(8):
      Getah virus (GETV) is a zoonotic virus transmitted by mosquitoes, belonging to the Togaviridae family, Alphavirus genus. It was first isolated from mosquitoes in Malaysia in 1955, being widespread in island countries in the South Pacific region. Since the beginning of the 21st century, GETV expanded its range and geographical distribution from low-latitude tropical regions to 60° north latitude, being isolated from 17 different species of mosquitoes belonging to five genera of Culicidae (Culex, Anopheles, Armigeres, Aedes and Mansonia), as well as from midges in Eurasia. Molecular genetic evolution analysis revealed large molecular differences between the mosquitoes currently circulating Eurasia and those in the South Pacific in 1950s. The number of disease outbreaks caused by GETV in animals is increasing alongside the types of animals infected, from horses and pigs to cattle, blue foxes and red pandas. The disease burden is severely underestimated, and the economic cost to livestock production remains unknown. Herein, we review GETV temporal and spatial distribution, molecular genetic evolution, transmission and data on disease outbreaks. This work provides a reference for public health workers engaged in GETV research and zoonotic disease prevention and control.
    Keywords:  Alphavirus; GETV; Getah virus; Togaviridae; emerging infection; molecular genetic evolution; virus spreading; virus transmission; zoonotic disease
    DOI:  https://doi.org/10.3390/pathogens11080945
  7. Sci Rep. 2022 Aug 23. 12(1): 14392
      The spread of malaria is related to climate change because temperature and rainfall are key parameters of climate change. Fluctuations in temperature affect the spread of malaria by lowering or speeding up its rate of transmission. The amount of rainfall also affects the transmission of malaria by offering a lot of sites suitable for mosquitoes to breed in. However, a high amount of rainfall does not have a great effect. Because of the high malaria incidence and the death rates in African regions, by using malaria incidence data, temperature data and rainfall data collected in 1901-2015, we construct and analyze climate networks to show how climate relates to the transmission of malaria in African countries. Malaria networks show a positive correlation with temperature and rainfall networks, except for the 1981-2015 period, in which the malaria network shows a negative correlation with rainfall.
    DOI:  https://doi.org/10.1038/s41598-022-18782-9
  8. Arch Insect Biochem Physiol. 2022 Aug 22. e21959
      Lipophorin is a major hemolymph lipoprotein found in insects with a molecular native mass of 700 kDa. In mosquitoes, two different types of apolipoproteins are characterized, apolipophorin-I (ApoLp-I, ~250 kDa) and apolipophorin-II (ApoLp-II, ~80 kDa). This concentration depends on the stage of development and the age of the insects. Lipophorins are best studied in mosquitoes of the genus Aedes and Anopheles. In this study, we analyze the lipophorin sequence and show the lipophorin purification of the Culex quinquefasciatus and the transcriptional profile of the lipophorin gene in different life cycle stages. Similar amino acid composition and molecular weights are founded in three mosquitoes species lipophorins amino acid sequence. The two subunits of purified lipophorin (Apo I and Apo II) showed molecular masses of approximately 248 and 93 kDa, like that found in other mosquitoes. A gradual increase in the lipophorin expression gene was obtained during the previtellogenic period and after feeding we obtained peak expression at 24 h after feeding. With our results, we conclude that C. quinquefasciatus protein sequence has the same characteristics as those observed in other mosquitoes and that the expression of its apolipophorins is induced by blood feeding.
    Keywords:  fat body; hemolymph; lipid; lipoprotein; mosquito
    DOI:  https://doi.org/10.1002/arch.21959
  9. Microbiol Spectr. 2022 Aug 25. e0128522
      Brazil accounted for a total number of 1,276,194 reported cases of chikungunya fever between 2014 and 2022. Additionally, since 2015, the country has experienced an increasing death toll, in which the Northeast and Southeast regions appear to report the worst scenarios. Although the CHIKV transmission dynamics have been studied in many parts of the country since its introduction in 2014, little is still known about chikungunya virus (CHIKV) transmission and genetic diversity in the state of Minas Gerais, located in southeast Brazil. Moreover, no studies have been published characterizing CHIKV genomic surveillance in this state. Thus, to retrospectively explore the CHIKV epidemic in Minas Gerais, we generated 40 genomes from clinical samples using Nanopore sequencing. Phylogenetic analysis indicated that multiple introductions of CHIKV occurred, likely from the northeastern Brazilian states, with the most recent common ancestral strain dating to early March 2016, which is in agreement with local epidemiological reports. Additionally, epidemiological data reveals a decline in the number of reported cases from 2017 to 2021, indicating that population immunity or changes in vector activity may have contributed to the decreasing waves of CHIKV infection. Together, our results shed light on the dispersion dynamics of CHIKV and show that infections decreased from March 2017 to January 2021 despite multiple introductions into Minas Gerais State. In conclusion, our study highlights the importance of combining genomic and epidemiological data in order to assist public health laboratories in monitoring and understanding the patterns and diversity of mosquito-borne viral epidemics. IMPORTANCE Arbovirus infections in Brazil, including chikungunya, dengue, yellow fever, and Zika, result in considerable morbidity and mortality and are pressing public health concerns. However, our understanding of these outbreaks is hampered by the limited availability of genomic data. In this study, we combine epidemiological analysis and portable genome sequencing to retrospectively describe the CHIKV epidemic in Minas Gerais between 2017 and 2021. Our results indicate that the East/Central/South African (ECSA) CHIKV lineage was introduced into Minas Gerais by three distinct events, likely from the North and Northeast regions of Brazil. Our study provides an understanding of how CHIKV initiates transmission in the region and illustrates that genomics in the field can augment traditional approaches to infectious disease surveillance and control.
    Keywords:  CHIKV; Nanopore sequencing; genomic monitoring; southeast Brazil
    DOI:  https://doi.org/10.1128/spectrum.01285-22
  10. Malar J. 2022 Aug 20. 21(1): 241
       BACKGROUND: As Indonesia aims for malaria elimination by 2030, provisional malaria epidemiology and risk factors evaluation are important in pursue of this national goal. Therefore, this study aimed to understand the risk factor of malaria in Northern Sumatera.
    METHODS: Malaria cases from 2019 to 2020 were obtained from the Indonesian Ministry of Health Electronic Database. Climatic variables were provided by the Center for Meteorology and Geophysics Medan branch office. Multivariable logistic regression was undertaken to understand the risk factors of imported malaria. A zero-inflated Poisson multivariable regression model was used to study the climatic drivers of indigenous malaria.
    RESULTS: A total of 2208 (indigenous: 76.0% [1679] and imported: 17.8% [392]) were reported during the study period. Risk factors of imported malaria were: ages 19-30 (adjusted odds ratio [AOR] = 3.31; 95% confidence interval [CI] 1.67, 2.56), 31-45 (AOR = 5.69; 95% CI 2.65, 12.20), and > 45 years (AOR = 5.11; 95% CI 2.41, 10.84). Military personnel and forest workers and miners were 1,154 times (AOR = 197.03; 95% CI 145.93, 9,131.56) and 44 times (AOR = 44.16; 95% CI 4.08, 477,93) more likely to be imported cases as compared to those working as employees and traders. Indigenous Plasmodium falciparum increased by 12.1% (95% CrI 5.1%, 20.1%) for 1% increase in relative humidity and by 21.0% (95% CrI 9.0%, 36.2%) for 1 °C increase in maximum temperature. Plasmodium vivax decreased by 0.8% (95% CrI 0.2%, 1.3%) and 16.7% (95% CrI 13.7%, 19.9%) for one meter and 1 °C increase of altitude and minimum temperature. Indigenous hotspot was reported by Kota Tanjung Balai city and Asahan regency, respectively. Imported malaria hotspots were reported in Batu Bara, Kota Tebing Tinggi, Serdang Bedagai and Simalungun.
    CONCLUSION: Both indigenous and imported malaria is limited to a few regencies and cities in Northern Sumatera. The control measures should focus on these risk factors to achieve elimination in Indonesia.
    Keywords:  Bayesian analysis; Elimination; Imported; Indigenous; Indonesia; Malaria; Northern Sumatera; Spatial analysis
    DOI:  https://doi.org/10.1186/s12936-022-04262-y
  11. Trop Med Infect Dis. 2022 Jul 31. pii: 160. [Epub ahead of print]7(8):
      In January 2022, West Nile virus (WNV) lineage 2 (L2) was detected in an adult female goshawk rescued near Perugia in the region of Umbria (Italy). The animal showed neurological symptoms and died 15 days after its recovery in a wildlife rescue center. This was the second case of WNV infection recorded in birds in the Umbria region during the cold season, when mosquitoes, the main WNV vectors, are usually not active. According to the National Surveillance Plan, the Umbria region is included amongst the WNV low-risk areas. The necropsy evidenced generalized pallor of the mucous membranes, mild splenomegaly, and cerebral edema. WNV L2 was detected in the brain, heart, kidney, and spleen homogenate using specific RT-PCR. Subsequently, the extracted viral RNA was sequenced. A Bayesian phylogenetic analysis performed through a maximum-likelihood tree showed that the genome sequence clustered with the Italian strains within the European WNV strains among the central-southern European WNV L2 clade. These results, on the one hand, confirmed that the WNV L2 strains circulating in Italy are genetically stable and, on the other hand, evidenced a continuous WNV circulation in Italy throughout the year. In this report case, a bird-to-bird WNV transmission was suggested to support the virus overwintering. The potential transmission through the oral route in a predatory bird may explain the relatively rapid spread of WNV, as well as other flaviviruses characterized by similar transmission patterns. However, rodent-to-bird transmission or mosquito-to-bird transmission cannot be excluded, and further research is needed to better understand WNV transmission routes during the winter season in Italy.
    Keywords:  West Nile virus; bird-to-bird transmission; birds of prey; flavivirus; hybrid mosquitoes; overwintering; rodent-to-bird transmission; surveillance
    DOI:  https://doi.org/10.3390/tropicalmed7080160
  12. J Infect Public Health. 2022 Aug 10. pii: S1876-0341(22)00207-6. [Epub ahead of print]15(9): 1025-1035
       INTRODUCTION: Dengue fever disease is affected by many scoioeconomic and enviromental factors throughout endemic areas globally. These factors contribute to increase the incidence of endemic dengue endemic in Jeddah, Saudi Arabia.
    OBJECTIVES: This study aimed to investigate the distribution and spatial patterns of dengue fever cases in Jeddah, and to determine if there is an association between dengue fever and the following environmental factors: temperature, humidity, land cover, climate, rainfall, epicenter of reproduction, and socioeconomic factors.
    METHODS: A descriptive and analytical cross-sectional study was conducted in Jeddah in 2020. The study included all reported suspected and confirmed dengue cases. The sample size was 1458 cases. Data were obtained from the Dengue Active Surveillance System and the confirmed cases were geo-distributed in areas by QGIS. All significant variables were included in the logistic regression table.
    RESULTS: The majority (61.9 %) were suspected cases and 38.1 % confirmed cases. The majority of the cases were male. The highest spatial distribution was in the middle of Jeddah and the lowest in the south. The highest temporal distribution for confirmed cases was in June, and for suspected cases in December. Age, gender, occupation, and area were all significantly associated with the dengue reported cases. Most all the enviromental factors were not statistically significant.
    CONCLUSION: The study showed three clusters of dengue fever and infection concentrated in the middle and east of Jeddah. The lack of investigation in the environmental factors regarding the dengue distribution and its impact on the population area has to be taken seriously and dengue intervention programs should be implemented to reduce the endemic dengue in Jeddah.
    Keywords:  Dengue; Endemic; Jeddah; Spatial; Temporal
    DOI:  https://doi.org/10.1016/j.jiph.2022.08.003
  13. BMC Public Health. 2022 Aug 25. 22(1): 1615
       BACKGROUND: Imported malaria cases could be considered one of the threats to malaria elimination. Therefore, increasing migrants' access to malaria preventive measures can play an essential role in maintaining appropriate conditions and preventing malaria outbreaks. This study aimed to provide detailed information about access, utilization, and barriers to using malaria protection tools in migrants to Iran.
    METHODS: This study was conducted in a vast region consisting of 4 provinces and 38 cities located in the south and southeast of the country. Study participants were migrants who moved to the study area in the past three months. A sample of 4163 migrants participated in the study. They were selected through a multi-stage sampling method to obtain a representative community sample. Data were collected through interviewer-administered questionnaires about participants' socio-demographic specification, commuting characteristics, travel aim, access, ways of preparing, and reasons to use or not to use malaria protection tools. Quantitative and qualitative variables were described and analyzed finally.
    RESULTS: The mean age of individuals was 28.6 ± 10.8, with a range of 3-88 years old. Migrants' country of origin was Afghanistan (56.6%), Pakistan (38.4%), and Iran (5%). Most migrants (69.2%) did not have malaria protection tools while staying in Iran. Among those who procured the protection tools, 74% used long-lasting insecticidal nets (LLINs), 13.4% used mosquito repellent sticks and coil, and 12.7% did not use any tools. Respectively, lack of knowledge about where they can get LLINs, followed by being expensive, unavailability in the market, not cooperation of health officer, and no need to use were expressed as the causes for having no access. The main reasons for non-using the tools were lack of knowledge about their application, followed by a defect in protection tools, ineffectiveness, and being harmful, respectively. Migrants who were supported by an employer accessed more to LLINs.
    CONCLUSIONS: This study reveals significant shortcomings in knowledge, access, and utilization of malaria protection tools among migrants in Iran. Inequitable access to public health services is predictable during migration; however, access to sustainable protection tools is recommended.
    Keywords:  Iran; Malaria; Migrants; Protection
    DOI:  https://doi.org/10.1186/s12889-022-13913-3
  14. Trop Med Infect Dis. 2022 Aug 12. pii: 180. [Epub ahead of print]7(8):
       BACKGROUND: Dengue has become one of the major vector-borne diseases, which has been an important public health concern. We aimed to estimate the disease burden of dengue in major endemic regions from 1990 to 2019, and explore the impact pattern of the socioeconomic factors on the burden of dengue based on the global burden of diseases, injuries, and risk factors study 2019 (GBD 2019).
    METHODS: Using the analytical strategies and data from the GBD 2019, we described the incidence and disability-adjusted life years (DALYs) of dengue in major endemic regions from 1990 to 2019. Furthermore, we estimated the correlation between dengue burden and socioeconomic factors, and then established an autoregressive integrated moving average (ARIMA) model to predict the epidemic trends of dengue in endemic regions. All estimates were proposed as numbers and age-standardized rates (ASR) per 100,000 population, with uncertainty intervals (UIs). The ASRs of dengue incidence were compared geographically and five regions were stratified by a sociodemographic index (SDI).
    RESULTS: A significant rise was observed on a global scale between 1990 and 2019, with the overall age-standardized rate (ASR) increasing from 557.15 (95% UI 243.32-1212.53) per 100,000 in 1990 to 740.4 (95% UI 478.2-1323.1) per 100,000 in 2019. In 2019, the Oceania region had the highest age-standardized incidence rates per 100,000 population (3173.48 (95% UI 762.33-6161.18)), followed by the South Asia region (1740.79 (95% UI 660.93-4287.12)), and then the Southeast Asia region (1153.57 (95% UI 1049.49-1281.59)). In Oceania, South Asia, and Southeast Asia, increase trends were found in the burden of dengue fever measured by ASRs of DALY which were consistent with ASRs of dengue incidence at the national level. Most of the countries with the heaviest burden of dengue fever occurred in areas with low and medium SDI regions. However, the burden in high-middle and high-SDI countries is relatively low, especially the Solomon Islands and Tonga in Oceania, the Maldives in South Asia and Indonesia in Southeast Asia. The age distribution results of the incidence rate and disease burden of dengue fever of major endemic regions showed that the higher risk and disease burden are mainly concentrated in people under 14 or over 70 years old. The prediction by ARIMA showed that the risk of dengue fever in South and Southeast Asia is on the rise, and further prevention and control is warranted.
    CONCLUSIONS: In view of the rapid population growth and urbanization in many dengue-endemic countries, our research results are of great significance for presenting the future trend in dengue fever. It is recommended to policy makers that specific attention needs to be paid to the negative impact of urbanization on dengue incidence and allocate more resources to the low-SDI areas and people under 14 or over 70 years old to reduce the burden of dengue fever.
    Keywords:  burden; dengue; endemic regions; incidence; model
    DOI:  https://doi.org/10.3390/tropicalmed7080180
  15. Int J Environ Res Public Health. 2022 Aug 16. pii: 10105. [Epub ahead of print]19(16):
      Climate changes in the eastern part of Sahelian regions will induce an increase in rainfalls and extreme climate events. In this area, due to the intense events and floods, malaria transmission, a climate sensitive disease, is thus slowly extending in time to the drought season and in areas close to the border of the desert. Vectors can as well modify their area of breeding. Control programs must be aware of these changes to adapt their strategies.
    Keywords:  Sahel; climate change; floods; malaria
    DOI:  https://doi.org/10.3390/ijerph191610105
  16. Malar J. 2022 Aug 25. 21(1): 245
       BACKGROUND: The goal of this study was to understand the epidemiological characteristics of imported malaria in Shanghai specifically during the epidemic period of novel corona-virus pneumonia (COVID-19), to provide a reference for preventing the transmission of imported malaria after this disease had been previously eliminated.
    METHODS: The data of malaria cases reported in Shanghai from 2020 to 2021 were obtained from the China Information System for Disease Control and Prevention (CISDCP) and the Information System for Parasitic Disease Control and Prevention (ISPDCP). The characteristics of demographic and epidemiological distribution, travel-related information, diagnosis information, regions of infection acquisition and disposal information of epidemic situation were analysed with descriptive statistics.
    RESULTS: A total of 112 cases of malaria were reported in Shanghai from January 2020 to December 2021. There were 18 cases and 94 cases in 2020 and 2021, respectively, reaching the lowest and highest levels in the past 10 years. The incidence of malaria associated with seasons had an increasing trend (χ2 = 81.143, P < 0.05). These cases included Plasmodium falciparum (97, 86.61%), Plasmodium vivax (4, 3.57%), Plasmodium ovale (8, 7.14%) and Plasmodium malariae (3, 2.68%). The median age of patients with malaria was 38.0 years, the majority of these individuals were males (109, 97.32%), and most of them were labour personnel (93, 83.04%). Of the reported cases, 8 of these individuals (7.14%) reported experiencing malaria symptoms before their arrival in China after their stay overseas; 97 of these individuals (86.61%) reported experiencing symptoms within 14 days after their initial arrival from overseas; 15 of these individuals (13.39%) were diagnosed with 'severe malaria'; and 4 of these individuals (3.57%) were also diagnosed with COVID-19. All cases were imported from Africa, and there were no indigenous cases and deaths.
    CONCLUSION: Due to the impact of COVID-19, the number of imported malaria cases in Shanghai had greatly increased; however, prevention and control measures for imported malaria could be implemented to prevent re-transmission of this condition. Considering that the number of individuals returning from overseas labour is likely to increase in the next few years, it is necessary to strengthen the surveillance of imported malaria and to review the protocol for potential epidemic situations. Together, these measures could support the maintation of free-malaria status in Shanghai.
    Keywords:  COVID-19; Epidemiology; Imported case; Malaria; Shanghai
    DOI:  https://doi.org/10.1186/s12936-022-04273-9