bims-mosdis Biomed News
on Mosquito distribution and disease
Issue of 2023–07–23
nine papers selected by
Richard Halfpenny, Staffordshire University
  1. The reemergence of dengue virus in Sudan.
  2. Sibling Species Composition and Susceptibility Status of Anopheles gambiae s.l. to Insecticides Used for Indoor Residual Spraying in Eastern Uganda.
  3. An ecological assessment of the potential pandemic threat of Dengue Virus in Zhejiang province of China.
  4. Analysis of dengue fever disease in West Africa.
  5. Knowledge, attitude, and practice of healthcare workers regarding dengue fever in Mazandaran Province, northern Iran.
  6. Report on the first two confirmed autochthonous cases of West Nile virus encephalitis in Catalonia, Spain.
  7. Global prevalence of Asymptomatic Dengue infections - A systematic review and meta-analysis.
  8. From dengue outbreaks to endemicity: Reunion Island, France, 2018 to 2021.
  9. West Nile virus emergence in humans in Extremadura, Spain 2020.
  1. J Infect Public Health. 2023 Jul 07. pii: S1876-0341(23)00237-X. [Epub ahead of print]16(9): 1392-1395
    The reemergence of dengue virus in Sudan.
    Mujahed I Mustafa, Abdelrafie M Makhawi.
      Dengue fever (DF) is a mosquito-transmitted arboviral disease caused by 1 of 4 closely related but antigenically distinct serotypes of dengue virus (DENV), DENV-1-4. The primary vector of DENV is Aedes aegypti and Aedes albopictus mosquitoes. Humans are the main carrier of the virus and the amplifying host with non-human primates plays a considerable role in sylvatic cycle. On November 8, 2022, an outbreak of dengue fever has killed at least five people in North Kordofan State. On 23 Nov 2022, the Sudanese Ministry of Health reported 3326 cases of dengue fever across 8 Sudanese States; while 23 patients died from the fever. Sudan is witnessing its worst outbreak of dengue fever in over a decade, especially in North and South Kordofan and Red Sea State are hit hard. In this review, we will focus on the recent outbreak of dengue fever in many Sudanese states.
    Keywords:  Aedes aegypti; Dengue fever; Dengue virus (DENV); Infectious diseases
    DOI:  https://doi.org/10.1016/j.jiph.2023.07.002
  2. J Parasitol Res. 2023 ;2023 2225233
    Sibling Species Composition and Susceptibility Status of Anopheles gambiae s.l. to Insecticides Used for Indoor Residual Spraying in Eastern Uganda.
    Julius Iga, Stephen Ochaya, Richard Echodu, Elizabeth A Opiyo, Alex K Musiime, Angella Nakamaanya, Geoffrey M Malinga.
       Background: Malaria remains one of the most critical disease causing morbidity and mortality in Uganda. Indoor residual spraying (IRS) and the use of insecticide-treated bed nets are currently the predominant malaria vector control interventions. However, the emergence and spread of insecticide resistance among malaria vectors threaten the continued effectiveness of these interventions to control the disease, particularly in high transmission areas. To inform decisions on vector control, the current study evaluated the Anopheles malaria vector species and their susceptibility levels to 0.1% bendiocarb and 0.25% pirimiphos-methyl insecticides used in IRS intervention program in Namutumba district, Eastern Uganda.
    Methods: Anopheles larvae were collected between March and May 2017 from different breeding sites in the parishes of Nsinze and Nawaikona in Nsinze sub-county and reared to adults to assess the susceptibility status of populations in the study area. Mosquitoes were identified using morphological keys and species-specific polymerase chain reaction (PCR) assays. Susceptibility tests were conducted on 2- to 5-day-old non-blood-fed adult female Anopheles that emerged using insecticide-impregnated papers with 0.1% bendiocarb and 0.25% pirimiphos-methyl following standard World Health Organization (WHO) insecticide susceptibility bioassays. A Log-probit regression model was used to derive the knock-down rates for 50% and 95% of exposed mosquitoes.
    Results: A total of 700 mosquito larvae were collected from different breeding sites. Morphological identification showed that 500 individuals that emerged belonged to Anopheles gambiae sensu lato (s.l.), the main malaria vector. The PCR results showed that the dominant sibling species under the A. gambiae complex was Anopheles arabiensis 99.5% (395/397). WHO bioassay tests revealed that the population of mosquitoes exhibited high levels of susceptibility (24-hour post-exposure mortality 98-100%) to both insecticides tested. The median knock-down time, KDT50, ranged from 6.6 to 81.4 minutes, while the KDT95 ranged from 21.6 to 118.9 minutes for 0.25% pirimiphos-methyl. The KDT50 for 0.1% bendiocarb ranged from 2.8 to 62.9 minutes, whereas the KDT95 ranged from 36.0 to 88.5 minutes.
    Conclusions: These findings indicate that bendiocarb and pirimiphos-methyl are still effective against the major malaria vector, A. arabiensis in Nsinze sub-county, Namutumba district, Uganda and can be effectively used for IRS. The study has provided baseline information on the insecticide susceptibility status on malaria vectors in the study area. However, routine continuous monitoring program of insecticide susceptibility and malaria vector composition is required so as to guide future decisions on insecticide use for IRS intervention toward malaria elimination and to track future changes in vector population.
    DOI:  https://doi.org/10.1155/2023/2225233
  3. BMC Infect Dis. 2023 Jul 17. 23(1): 473
    An ecological assessment of the potential pandemic threat of Dengue Virus in Zhejiang province of China.
    Yaxing Zhang, Lei Wang, Guozhen Wang, Jiabao Xu, Tianxing Zhang.
       BACKGROUND AND AIM: Dengue fever, transmitted by Aedes mosquitoes, is a significant public health concern in tropical and subtropical regions. With the end of the COVID-19 pandemic and the reopening of the borders, dengue fever remains a threat to mainland China, Zhejiang province of China is facing a huge risk of importing the dengue virus. This study aims to analyze and predict the current and future potential risk regions for Aedes vectors distribution and dengue prevalence in Zhejiang province of China.
    METHOD: We collected occurrence records of DENV and DENV vectors globally from 2010 to 2022, along with historical and future climate data and human population density data. In order to predict the probability of DENV distribution in Zhejiang province of China under future conditions, the ecological niche of Ae. aegypti and Ae. albopictus was first performed with historical climate data based on MaxEnt. Then, predicted results along with a set of bioclimatic variables, elevation and human population density were included in MaxEnt model to analyze the risk region of DENV in Zhejiang province. Finally, the established model was utilized to predict the spatial pattern of DENV risk in the current and future scenarios in Zhejiang province of China.
    RESULTS: Our findings indicated that approximately 89.2% (90,805.6 KM2) of Zhejiang province of China is under risk, within about 8.0% (8,144 KM2) classified as high risk area for DENV prevalence. Ae. albopictus were identified as the primary factor influencing the distribution of DENV. Future predictions suggest that sustainable and "green" development pathways may increase the risk of DENV prevalence in Zhejiang province of China. Conversely, Fossil-fueled development pathways may reduce the risk due to the unsuitable environment for vectors.
    CONCLUSIONS: The implications of this research highlight the need for effective vector control measures, community engagement, health education, and environmental initiatives to mitigate the potential spread of dengue fever in high-risk regions of Zhejiang province of China.
    Keywords:  Aedes albopictus; Climate change; Dengue virus; Jackknife test; MaxEnt
    DOI:  https://doi.org/10.1186/s12879-023-08444-0
  4. Exp Biol Med (Maywood). 2023 Jul 15. 15353702231181356
    Analysis of dengue fever disease in West Africa.
    Prince Gyasi, Michael Bright Yakass, Osbourne Quaye.
      Dengue fever disease (DFD) which is caused by four antigenically distinct dengue viruses (DENV) presents a global health threat, with tropical and subtropical regions at a greater risk. The paucity of epidemiological data on dengue in West African subregion endangers efforts geared toward disease control and prevention. A systematic search of DFD prevalence, incidence, and DENV-infected Aedes in West Africa was conducted in PubMed, Scopus, African Index Medicus, and Google Scholar in line with the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines. A total of 58 human prevalence studies involving 35,748 people from 8 countries were identified. Two incidence and six DENV-infected studies were also reviewed. Nigeria and Burkina Faso contributed the majority of the prevalence studies which spanned between 1968 and 2018, with a considerable variation in coverage among the countries reviewed in this study. An average prevalence of 20.97% was observed across both general prevalence and acute DENV infection study categories, ranging between 0.02% and 93%. The majority of these studies were conducted in acute febrile patients with a prevalence range of 0.02-93% while 19% (n = 11) of all studies were general population-based studies and reported a prevalence range of 17.2-75.8%. DENV-infected Aedes aegypti were reported in four out of the five countries with published reports; with DENV-2 found circulating in Cape Verde, Senegal, and Burkina Faso while DENV-3 and DENV-4 were also reported in Senegal and Cape Verde, respectively. High prevalence of DFD in human populations and the occurrence of DENV-infected A. aegypti have been reported in West Africa, even though weaknesses in study design were identified. Epidemiological data from most countries and population in the subregion were scarce or non-existent. This study highlights the epidemic risk of DFD in West Africa, and the need for research and surveillance to be prioritized to fill the data gap required to enact effective control measures.
    Keywords:  Aedes mosquito vectors; Dengue fever disease; West Africa disease burden; dengue epidemiological data; dengue fever virus; dengue geographical distribution
    DOI:  https://doi.org/10.1177/15353702231181356
  5. Front Public Health. 2023 ;11 1129056
    Knowledge, attitude, and practice of healthcare workers regarding dengue fever in Mazandaran Province, northern Iran.
    Seyed Hassan Nikookar, Mahmood Moosazadeh, Mahmoud Fazeli-Dinan, Morteza Zaim, Mohammad Mehdi Sedaghat, Ahmadali Enayati.
       Background: Dengue fever is a rapidly emerging infection worldwide with a high public health burden. Adequate training of healthcare workers is essential to warrant the timely provision of health services to improve the outcome of dengue management.
    Methods: This is an analytical cross-sectional study, conducted to assess the knowledge, attitudes and practice (KAP) of healthcare workers regarding dengue from April 2021 to March 2022 in Mazandaran Province, northern Iran. Data was collected using a researcher-made structured questionnaire, prepared as Google Forms, and sent to target groups through social media and email. Data analysis was performed by SPSS 22 software using descriptive and inferential statistics (Chi-square) at a significant level of 5%.
    Results: Most of the respondents had heard about dengue (83.8%); media (32.7%) and academic education (25%) were the main sources of information. Respondents had less knowledge associated with dengue symptoms (52%) than prevention and control (69%), transmission (72.2%) and clinical management (81%). Based on the 70% cut-off point, the majority of the participants had a good attitude (81%) and practice (73%). However, only 49.6% of the respondents showed good practice regarding dengue local transmission. A significant difference was observed between participants knowledge on clinical management with occupation; attitude with gender and occupation; and practice with gender (p < 0.05).
    Conclusion: The results of this study revealed gaps in some dimensions of KAP in healthcare workers, therefore, a greater focus should be placed on future training programs to raise knowledge and attitude leading to sound practice and behavior for adequate management of dengue.
    Keywords:  Aedes; Mazandaran; attitude; dengue; knowledge; northern Iran; practice
    DOI:  https://doi.org/10.3389/fpubh.2023.1129056
  6. Infect Dis (Lond). 2023 Jul 20. 1-5
    Report on the first two confirmed autochthonous cases of West Nile virus encephalitis in Catalonia, Spain.
    Carles García-Cervera, Simona Mihaela Iftimie, Miguel J Martínez, Ana Vázquez González, Sandra Parra-Pérez, Laia Revuelta-López-Cordón, Joan Gil-Toral, Rosa Mercè Vileu Vallverdu, Ana Martínez Mateo, Ana Felisa López-Azcona, Isabel Pujol-Bajador, Frederic Ballester-Bastardie, Antoni Castro-Salomó.
       BACKGROUND: West Nile virus (WNV) is a mosquito-borne flavivirus that can cause Central Nervous System infection in humans. Previous autochthonous cases of WNV encephalitis have been described in Spain, but none in Catalonia.
    MATERIALS AND METHODS: We report on the first two autochthonous cases of encephalitis in humans caused by the West Nile virus (WNV) diagnosed in Catalonia (northeastern region of Spain).
    RESULTS: An old married couple presented with clinical and biological signs compatible with viral encephalitis. Acute and convalescent serum samples showed IgM and IgG positivity for WNV. In addition, IgM was also detected in cerebrospinal fluid in the male patient. The serological results were later confirmed by microneutralization assays.
    CONCLUSIONS: WNV infection must be considered in patients presenting with meningoencephalitis with viral CSF characteristics when common pathogens are excluded.
    Keywords:  West Nile virus; arboviruses; encephalitis; viruses
    DOI:  https://doi.org/10.1080/23744235.2023.2236703
  7. Int J Infect Dis. 2023 Jul 16. pii: S1201-9712(23)00660-4. [Epub ahead of print]
    Global prevalence of Asymptomatic Dengue infections - A systematic review and meta-analysis.
    P R Asish, Sauvik Dasgupta, Gladys Rachel, Bhavani Shankara Bagepally, C P Girish Kumar.
       OBJECTIVE: The burden of asymptomatic Dengue infections is understudied. Therefore, we systematically reviewed the literature to estimate the global prevalence of asymptomatic Dengue infections.
    METHODS: We searched cross-sectional studies reporting the prevalence of asymptomatic Dengue infections from PubMed, Scopus, and Embase. Prevalence of asymptomatic dengue infections was pooled and reported as proportions with a 95% confidence interval. This systematic review protocol was a priori registered in PROSPERO (Reg: No. CRD42020218446).
    RESULTS: We included 41 studies with 131,953 cases in our analysis. The overall pooled prevalence of asymptomatic Dengue infections was 59.26% (95% CI: 43.76 - 74.75, I2 = 99.93%), with 65.52% (95% CI: 38.73 - 92.32, I2 = 99.95%) during outbreaks and 30.78% (95% CI: 21.39 - 40.16, I2 = 98.78%) during non-outbreak periods. The pooled prevalence among the acutely infected individuals was 54.52% (95% CI: 17.73 - 46.76, I2 = 99.91%), whereas among primary and secondary asymptomatic Dengue infections, it was 65.36% (95% CI: 45.76 - 84.96, I2 = 98.82) and 48.99% (95% CI: 27.85 - 70.13, I2 = 99.08%) respectively.
    CONCLUSION: The majority of Dengue cases are asymptomatic and may play a significant role in disease transmission. Public health strategies aimed at Dengue outbreak response and mitigation of disease burden should include early detection of asymptomatic cases.
    Keywords:  Dengue; asymptomatic; global; meta-analysis; prevalence; systematic review
    DOI:  https://doi.org/10.1016/j.ijid.2023.07.010
  8. Euro Surveill. 2023 Jul;28(29):
    From dengue outbreaks to endemicity: Reunion Island, France, 2018 to 2021.
    Clinical Investigation Team
      BackgroundAfter 40 years of limited viral circulation, Reunion Island has since 2018 experienced recurrent dengue outbreaks of increasing intensity and severity.AimWe aimed to report on the epidemiology and characteristics of dengue in Reunion Island between 2018 and 2021.MethodsBetween 2018 and August 2021, we systematically collected data on dengue cases via an automated transmission system between the health authorities and the medical laboratories. We set up additional surveillance systems for dengue-related activity in primary care, in emergency departments and in inpatient departments.ResultsUntil 2020, despite numerous cases, outbreaks had a limited public health impact because of few severe cases, low lethality and no heavy burden for the health care system. In 2021, however, the number of severe cases increased (from 0.4% of all cases in 2018 to 0.8% in 2021), as did the number of paediatric cases (from 8% in 2018 to 15% in 2021) and atypical clinical forms of dengue (108 cases of post-dengue maculopathy). Of note, haemorrhagic forms were rare and multi-organ failure was the most frequent severity throughout the study period. In parallel, the dominant serotype switched from DENV2 to DENV1 in 2020 and DENV1 became the only serotype detected in 2021.ConclusionThese findings indicate that dengue is becoming endemic in Reunion Island. Since comorbidities associated with severity of dengue are common in the population, health authorities should carefully consider the impact of dengue when addressing public health policies.
    Keywords:  Dengue; Endemisation; Reunion Island; Severity; Surveillance
    DOI:  https://doi.org/10.2807/1560-7917.ES.2023.28.29.2200769
  9. Front Cell Infect Microbiol. 2023 ;13 1155867
    West Nile virus emergence in humans in Extremadura, Spain 2020.
    Alicia Macias, Paloma Martín, Mayte Pérez-Olmeda, Beatriz Fernández-Martínez, Diana Gómez-Barroso, Esperanza Fernández, Julian Mauro Ramos, Laura Herrero, Saray Rodríguez, Elena Delgado, Maria Paz Sánchez-Seco, Miguel Galán, Antonio Jesús Corbacho, Manuel Jimenez, Cristian Montero-Peña, Antonio Valle, Ana Vázquez.
      In Spain, the largest human West Nile virus (WNV) outbreak among humans was reported in 2020, constituting the second most important outbreak in Europe that season. Extremadura (southwestern Spain) was one of the affected areas, reporting six human cases. The first autochthonous human case in Spain was reported in Extremadura in 2004, and no other human cases were reported until 2020. In this work, we describe the first WNV human outbreak registered in Extremadura, focusing on the most important clinical aspects, diagnostic results, and control actions which followed. In 2020, from September to October, human WNV infections were diagnosed using a combination of molecular and serological methods (an in-house specific qRT-PCR and a commercial ELISA for anti-WNV IgM and IgG antibodies) and by analysing serum, urine, and/or cerebrospinal fluid samples. Serological positive serum samples were further tested using commercial kits against related flaviviruses Usutu and Tick-borne encephalitis in order to analyse serological reactivity and to confirm the results by neutralisation assays. In total, six cases of WNV infection (five with neuroinvasive disease and one with fever) were identified. Clinical presentation and laboratory findings are described. No viral RNA was detected in any of the analysed samples, but serological cross-reactivity was detected against the other tested flaviviruses. Molecular and serological methods for WNV detection in various samples as well as differential diagnosis are recommended. The largest number of human cases of WNV infection ever registered in Extremadura, Spain, occurred in 2020 in areas where circulation of WNV and other flaviviruses has been previously reported in humans and animals. Therefore, it is necessary to enhance surveillance not only for the early detection and implementation of response measures for WNV but also for other emerging flaviviruses that could be endemic in this area.
    Keywords:  West Nile virus; diagnosis; flaviviruses; human infection; molecular and serological methods; surveillance
    DOI:  https://doi.org/10.3389/fcimb.2023.1155867
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