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Somé BM, Guissou E, Da DF, Richard Q, Choisy M, Yameogo KB, Hien DF, Yerbanga RS, Ouedraogo GA, Dabiré KR, Djidjou-Demasse R, Cohuet A, Lefèvre T. Mosquito ageing modulates the development, virulence and transmission potential of pathogens. Proc Biol Sci 2024; 291:20232097. [PMID: 38166422 PMCID: PMC10762442 DOI: 10.1098/rspb.2023.2097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 11/27/2023] [Indexed: 01/04/2024] Open
Abstract
Host age variation is a striking source of heterogeneity that can shape the evolution and transmission dynamic of pathogens. Compared with vertebrate systems, our understanding of the impact of host age on invertebrate-pathogen interactions remains limited. We examined the influence of mosquito age on key life-history traits driving human malaria transmission. Females of Anopheles coluzzii, a major malaria vector, belonging to three age classes (4-, 8- and 12-day-old), were experimentally infected with Plasmodium falciparum field isolates. Our findings revealed reduced competence in 12-day-old mosquitoes, characterized by lower oocyst/sporozoite rates and intensities compared with younger mosquitoes. Despite shorter median longevities in older age classes, infected 12-day-old mosquitoes exhibited improved survival, suggesting that the infection might act as a fountain of youth for older mosquitoes specifically. The timing of sporozoite appearance in the salivary glands remained consistent across mosquito age classes, with an extrinsic incubation period of approximately 13 days. Integrating these results into an epidemiological model revealed a lower vectorial capacity for older mosquitoes compared with younger ones, albeit still substantial owing to extended longevity in the presence of infection. Considering age heterogeneity provides valuable insights for ecological and epidemiological studies, informing targeted control strategies to mitigate pathogen transmission.
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Affiliation(s)
- Bernard M. Somé
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
- Département de Biochimie, Université Nazi Boni, 01 BP 1091 Bobo Dioulasso, Burkina Faso
| | - Edwige Guissou
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
- Département de Biochimie, Université Nazi Boni, 01 BP 1091 Bobo Dioulasso, Burkina Faso
- MIVEGEC, IRD, CNRS, University of Montpellier, 34090 Montpellier cedex 5, France
- Ecole Normale Supérieure, BP 376 Koudougou, Burkina Faso
| | - Dari F. Da
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
| | - Quentin Richard
- IMAG, Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Marc Choisy
- Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 700000, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Koudraogo B. Yameogo
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Domombabele FdS. Hien
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Rakiswende S. Yerbanga
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Georges A. Ouedraogo
- Département de Biochimie, Université Nazi Boni, 01 BP 1091 Bobo Dioulasso, Burkina Faso
| | - Kounbobr R. Dabiré
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | | | - Anna Cohuet
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
- MIVEGEC, IRD, CNRS, University of Montpellier, 34090 Montpellier cedex 5, France
| | - Thierry Lefèvre
- Unité Paludisme et Maladies Tropicales Négligées, Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545 Bobo Dioulasso, Burkina Faso
- Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
- MIVEGEC, IRD, CNRS, University of Montpellier, 34090 Montpellier cedex 5, France
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O'Keeffe FE, Pendleton RC, Holland CV, Luijckx P. Increased virulence due to multiple infection in Daphnia leads to limited growth in 1 of 2 co-infecting microsporidian parasites. Parasitology 2024; 151:58-67. [PMID: 37981808 PMCID: PMC10941049 DOI: 10.1017/s0031182023001130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/21/2023]
Abstract
Recent outbreaks of various infectious diseases have highlighted the ever-present need to understand the drivers of the outbreak and spread of disease. Although much of the research investigating diseases focuses on single infections, natural systems are dominated by multiple infections. These infections may occur simultaneously, but are often acquired sequentially, which may alter the outcome of infection. Using waterfleas (Daphnia magna) as a model organism, we examined the outcome of sequential and simultaneous multiple infections with 2 microsporidian parasites (Ordospora colligata and Hamiltosporidium tvaerminnensis) in a fully factorial design with 9 treatments and 30 replicates. We found no differences between simultaneous and sequential infections. However, H. tvaerminnensis fitness was impeded by multiple infection due to increased host mortality, which gave H. tvaerminnensis less time to grow. Host fecundity was also reduced across all treatments, but animals infected with O. colligata at a younger age produced the fewest offspring. As H. tvaerminnensis is both horizontally and vertically transmitted, this reduction in offspring may have further reduced H. tvaerminnensis fitness in co-infected treatments. Our findings suggest that in natural populations where both species co-occur, H. tvaerminnensis may evolve to higher levels of virulence following frequent co-infection by O. colligata.
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Affiliation(s)
- Floriane E. O'Keeffe
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Rebecca C. Pendleton
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Celia V. Holland
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Pepijn Luijckx
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
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Kun Á, Hubai AG, Král A, Mokos J, Mikulecz BÁ, Radványi Á. Do pathogens always evolve to be less virulent? The virulence–transmission trade-off in light of the COVID-19 pandemic. Biol Futur 2023:10.1007/s42977-023-00159-2. [PMID: 37002448 PMCID: PMC10066022 DOI: 10.1007/s42977-023-00159-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 03/09/2023] [Indexed: 04/03/2023]
Abstract
AbstractThe direction the evolution of virulence takes in connection with any pathogen is a long-standing question. Formerly, it was theorized that pathogens should always evolve to be less virulent. As observations were not in line with this theoretical outcome, new theories emerged, chief among them the transmission–virulence trade-off hypotheses, which predicts an intermediate level of virulence as the endpoint of evolution. At the moment, we are very much interested in the future evolution of COVID-19’s virulence. Here, we show that the disease does not fulfill all the assumptions of the hypothesis. In the case of COVID-19, a higher viral load does not mean a higher risk of death; immunity is not long-lasting; other hosts can act as reservoirs for the virus; and death as a consequence of viral infection does not shorten the infectious period. Consequently, we cannot predict the short- or long-term evolution of the virulence of COVID-19.
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Sorci G, Faivre B. Age-dependent virulence of human pathogens. PLoS Pathog 2022; 18:e1010866. [PMID: 36137159 PMCID: PMC9531802 DOI: 10.1371/journal.ppat.1010866] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 10/04/2022] [Accepted: 09/08/2022] [Indexed: 11/19/2022] Open
Abstract
Host age is often evoked as an intrinsic factor aggravating the outcome of host-pathogen interactions. However, the shape of the relationship between age and infection-induced mortality might differ among pathogens, with specific clinical and ecological traits making some pathogens more likely to exert higher mortality in older hosts. Here, we used a large dataset on age-specific case fatality rate (CFR) of 28 human infectious diseases to investigate i) whether age is consistently associated to increased CFR, ii) whether pathogen characteristics might explain higher CFR in older adults. We found that, for most of the infectious diseases considered here, CFR slightly decreased during the first years of life and then steeply increased in older adults. Pathogens inducing diseases with long-lasting symptoms had the steepest increase of age-dependent CFR. Similarly, bacterial diseases and emerging viruses were associated with increasing mortality risk in the oldest age classes. On the contrary, we did not find evidence suggesting that systemic infections have steeper slopes between CFR and age; similarly, the relationship between age and CFR did not differ according to the pathogen transmission mode. Overall, our analysis shows that age is a key trait affecting infection-induced mortality rate in humans, and that the extent of the aggravating effect on older adults depends on some key traits, such as the duration of illness. Mortality due to infectious diseases varies tremendously among infectious agents, with some pathogens producing no mortality, and others being often associated with a fatal outcome. Such variability depends on characteristics of the pathogen, the host and the environment where hosts and pathogens interact. Age is one of the main host traits that accounts for differences in infection-induced mortality (with mortality being higher at the extremes of the age spectrum). Here, we used a large dataset on 28 human infectious diseases to explore the clinical and ecological traits that might account for differences in age-specific mortality risk. We found that pathogens producing long-lasting disease symptoms exert the highest mortality risk in the older adults. Similarly, emerging pathogens are also associated with higher mortality risk in the oldest age classes. These results confirm that age is a key trait affecting infection-induced mortality rate in humans, and show that the extent of the aggravating effect in older adults depends on some key traits, such as the duration of illness.
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Affiliation(s)
- Gabriele Sorci
- Biogéosciences, UMR 6282 CNRS, Université de Bourgogne Franche-Comté, Dijon, France
- * E-mail:
| | - Bruno Faivre
- Biogéosciences, UMR 6282 CNRS, Université de Bourgogne Franche-Comté, Dijon, France
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