Despite decades of advances and understanding of the indiscriminate nature of human immunodeficiency virus (HIV), it remains shrouded in stigma that makes it difficult to reach some key populations at risk of transmission. The advent of self-testing technology for HIV (HIVST) has opened much-needed potential for bringing privacy to prevention that is crucial for curtailing its continued spread (Johnson et al., 2014). The HIV Self-Testing in Africa (STAR) Initiative (https://www.psi.org/fr/project/star/), carried out in Eastern and Southern Africa between 2015 and 2020 (Simwinga et al., 2022), demonstrated the market and public health operational potential of HIVST of different distribution methods. From 2019 to 2022, the “AutoTest de dépistage du VIH : Libre d’Accéder à la connaissance de son Statut" (ATLAS, translating to “HIVST: Freedom to know your status”) program built on these findings to quantify the public health value of HIVST for reaching key populations in West Africa (specifically, Mali, Senegal and Côte d’Ivoire) (Ky-Zerbo et al., 2022).

The innovative secondary distribution methods these studies employed, where the primary targeted populations were also encouraged to take and provide tests to their contacts, helped widen the reach of HIVST within key population networks beyond those relying on access to HIV testing facilities.

The tricky part of the self-testing model lies in assessing its reach and impact while maintaining the privacy of self-testers that is central to its success. Following voluntary phone survey methods that previously were able to show expanded reach of HIVST to first-time testers in key populations in West Africa and high rates of confirmatory testing and treatment seeking (Kra et al., 2022), Kra et al. (Kra et al., 2024) quantified how many of these self-tests led to a positive result – allowing wider assessment of follow-up behaviors and positivity rates among the hard-to-reach populations the program had targeted. 

While the numbers were low, the results were informative. Among respondents who reported a positive (“reactive”) HIVST, just 44% proceeded to confirmatory testing. This is lower than in other populations where HIVST follow-up has been assessed (Thirumurthy et al., 2016). The main reasons given for not confirming a reactive self-test was misinterpretation of HIVST results and not understanding that confirmatory testing was needed. The result thus highlighted a need for improved communication on how to correctly interpret HIVST results, and the authors provided ranges for how this misinterpretation could have affected their positivity estimates. However, the majority of those who sought confirmatory testing did so within 3 months, and nearly all of those with confirmed infection started on treatment. HIV positivity rates in the three countries were all higher than other published HIV positivity estimates (Giguère et al., 2021; Maheu-Giroux et al., 2019), suggesting that HIVST methods were highly effective at reaching the targeted communities. 

Finally, while the authors demonstrated their methods as an effective way of assessing the utility of HIVST campaigns and identifying ways to improve them, the follow-up surveys are likely too costly to replace current passive surveillance methods for assessing community disease burden. That said, these precious data should be taken as validation of the public health value of HIV self-testing in key populations across communities in West Africa. With improvements in communicating instructions for use and follow-up, there is little doubt that the innovation of HIVST primary and secondary distribution could become a widely useful addition to the fight against HIV. 

References

Giguère, K., Eaton, J. W., Marsh, K., Johnson, L. F., Johnson, C. C., Ehui, E., Jahn, A., Wanyeki, I., Mbofana, F., Bakiono, F., Mahy, M., & Maheu-Giroux, M. (2021). Trends in knowledge of HIV status and efficiency of HIV testing services in sub-Saharan Africa, 2000–20: a modelling study using survey and HIV testing programme data. The Lancet HIV, 8(5), e284–e293. https://doi.org/10.1016/S2352-3018(20)30315-5

Johnson, C., Baggaley, R., Forsythe, S., Van Rooyen, H., Ford, N., Napierala Mavedzenge, S., Corbett, E., Natarajan, P., & Taegtmeyer, M. (2014). Realizing the potential for HIV self-testing. In AIDS and Behavior (Vol. 18, Issue SUPPL. 4). Springer New York LLC. https://doi.org/10.1007/s10461-014-0832-x

Kra, A. K., Fosto, A. S., N’guessan, K. N., Geoffroy, O., Younoussa, S., Kabemba, O. K., Gueye, P. A., Ndeye, P. D., Rouveau, N., Boily, M. C., Silhol, R., d’Elbée, M., Maheu-Giroux, M., Vautier, A., & Larmarange, J. (2022). Can HIV self-testing reach first-time testers? A telephone survey among self-test end users in Côte d’Ivoire, Mali, and Senegal. BMC Infectious Diseases, 22. https://doi.org/10.1186/s12879-023-08626-w

Kra, A. K., Fotso, A. S., Rouveau, N., Maheu-Giroux, M., Boily, M.-C., Silhol, R., d’Elbée, M., Vautier, A., Lamarange, J., & the Atlas team. (2024). HIV self-testing positivity rate and linkage to confirmatory testing and care: a telephone survey in Côte d’Ivoire, Mali, and Senegal. MedRxiv, Ver. 4 Peer-Reviewed and Recommended by Peer Community in Infections, 2023.06.10.23291206. https://doi.org/https://doi.org/10.1101/2023.06.10.23291206

Ky-Zerbo, O., Desclaux, A., Boye, S., Maheu-Giroux, M., Rouveau, N., Vautier, A., Camara, C. S., Kouadio, B. A., Sow, S., Doumenc-Aidara, C., Gueye, P. A., Geoffroy, O., Kamemba, O. K., Ehui, E., Ndour, C. T., Keita, A., & Larmarange, J. (2022). “I take it and give it to my partners who will give it to their partners”: Secondary distribution of HIV self-tests by key populations in Côte d’Ivoire, Mali, and Senegal. BMC Infectious Diseases, 22. https://doi.org/10.1186/s12879-023-08319-4

Maheu-Giroux, M., Marsh, K., Doyle, C. M., Godin, A., Lanièce Delaunay, C., Johnson, L. F., Jahn, A., Abo, K., Mbofana, F., Boily, M. C., Buckeridge, D. L., Hankins, C. A., & Eaton, J. W. (2019). National HIV testing and diagnosis coverage in sub-Saharan Africa: A new modeling tool for estimating the “first 90” from program and survey data. AIDS, 33, S255–S269. https://doi.org/10.1097/QAD.0000000000002386

Simwinga, M., Gwanu, L., Hensen, B., Sigande, L., Mainga, M., Phiri, T., Mwanza, E., Kabumbu, M., Mulubwa, C., Mwenge, L., Bwalya, C., Kumwenda, M., Mubanga, E., Mee, P., Johnson, C. C., Corbett, E. L., Hatzold, K., Neuman, M., Ayles, H., & Taegtmeyer, M. (2022). Lessons learned from implementation of four HIV self-testing (HIVST) distribution models in Zambia: applying the Consolidated Framework for Implementation Research to understand impact of contextual factors on implementation. BMC Infectious Diseases, 22(Suppl 1). https://doi.org/10.1186/s12879-024-09168-5

Thirumurthy, H., Masters, S. H., Mavedzenge, S. N., Maman, S., Omanga, E., & Agot, K. (2016). Promoting male partner HIV testing and safer sexual decision making through secondary distribution of self-tests by HIV-negative female sex workers and women receiving antenatal and post-partum care in Kenya: a cohort study. The Lancet HIV, 3(6), e266–e274. https://doi.org/10.1016/S2352-3018(16)00041-2

Each and every one of us will recall the severe acute respiratory syndrome (SARS) coronavirus (CoV-2) pandemic, and the national and international political hesitations in its management. Fall 2019, in the city of Wuhan, Hubei province, China, an outbreak of unusual viral pneumonia due to a new emerging coronavirus named as SARS-CoV-2 started, generating late February a modern pandemic called COVID-19, posing very serious threat to global public health and the world economy (Hu et al. 2021). As we are getting out from this pandemic, and even if viral variants are still circulating, what have we learned and retained from this difficult period, shaking our certainties and reminding us of past images of devastating plagues? The COVID-19 pandemic highlighted the importance of early action, widespread testing, open data sharing, and strong public responses (The Lancet Infectious Diseases 2024). It has also highlighted that the animal origin of SARS-CoV-2 was still unknown and the existence of a reservoir host not really demonstrated (Cohen 2021). Beyond this, the COVID-19 pandemic has also revealed the importance of early and continuous surveillance, also raised questions about the role of meteorological conditions on the dispersion and viability of this virus, and highlighted the devastating effects of social inequality. We all remember some medical doctors who became modern preachers announcing the end of the pandemic because of unfavorable weather conditions coming for viral spread!

However, epidemiological studies analyzing the role of different parameters, and effects of national and regional restrictions at local or regional scales on COVID-19 are still rare. In this investigation entitled “Spatial and temporal epidemiology of SARS-3 CoV-2 virus lineages in Teesside, UK, in 2020: effects of socio-economic deprivation, weather, and lockdown on lineage dynamics”, Moss and collaborators’ aim is to analyze how a range of parameters, using both generalized linear mixed- and Bayesian spatial modeling, affected positive cases in the Teesside subregion of North East England during 2020 (Moss et al. 2024). Also, the authors wanted to understand the impacts of national and local government interventions introduced this year affected disease conditions in this subregion showing high levels of deprivation due to deindustrialisation in the latter half of the 20th century. 

According to Moss et al. (2024), the UK government decided for a heterogenous ”tier” system of local restrictions in England during the second wave associated with a more stringent national lockdown. The intention was to be more responsive and appropriate to the different English local contexts. The authors take us through a detailed statistical analysis to show that disease patterns in Teesside were associated with demographic parameters, social deprivation, weather conditions (essentially temperature) and governmental health interventions. Interestingly, findings lead to the conclusion that local tier interventions by public authorities was less effective at reducing COVID-19 cases in Teesside than a strict, long-term national lockdown.  A closer look at the spatio-temporal dynamics of the eight most common SARS-CoV-2 lineages circulating in Teesside in 2020 reveals complex dynamic behaviours differing to those of the total positive cases, certainly due to environmental and demographic stochasticity, and sublocal heterogenous social and economic conditions.

Overall, we recommend reading this study, which reveals the complexity of dealing with epidemics and pandemics, and highlights the importance of sound national political decisions and difficulties to proceed to local adjustments, i.e. tier system, in epidemic and pandemic control. 

The present recommendation is resulting from thorough reviews produced by Samuel Alizon and two anonymous reviewers, and which I thank very much for their review works here. 

References

Jon COHEN. 2021. Prophet in purgatory. Science 374, 1040-1045. https://www.science.org/doi/epdf/10.1126/science.acx9661

Ben HU, Hua GUO, Peng ZHOU, Zheng-Li SHI. 2021. Characteristics of SARS-CoV-2 and COVID-19. Nat Rev Microbiol 19, 141-54. https://doi.org/10.1038/s41579-020-00459-7 

The Lancet Infectious Diseases. 2024. Have we learned anything? Editorial. The Lancet Infectious Diseases 24, 793. https://doi.org/10.1016/S1473-3099(24)00439-0

E.D. Moss, S.P. Rushton, P. Baker, M. Bashton, M.R. Crown, R.N. dos Santos, A. Nelson, S.J. O’Brien, Z. Richards, R.A. Sanderson, W.C. Yew, G.R. Young, C.M. McCann, D.L. Smith (2024) Spatial and temporal epidemiology of SARS-CoV-2 virus lineages in Teesside, UK, in 2020: effects of socio-economic deprivation, weather, and lockdown on lineage dynamics. medRxiv, ver.5 peer-reviewed and recommended by PCI Infections. https://doi.org/10.1101/2022.02.05.22269279

Most plant-infecting viruses rely on an animal vector to be transmitted from one sessile host plant to another. A fascinating aspect of virus-vector interactions is the fact that viruses from different clades produce different proteins to bind vector receptors (1). Two major processes are described. In the “capsid strategy”, a motif of the capsid protein is directly binding to the vector receptor. In the “helper strategy”, a non-structural component, the helper component (HC), establishes a bridge between the virus particle and the vector’s receptor.   

In this exhaustive review focusing on hemipteran insect vectors, Di Mattia et al. (2) are revisiting the helper strategy in light of recent results. The authors first place the discoveries of the HC strategy in a historical context, suggesting that HC are exclusively found in non-circulative viruses (viruses that only attach to the vector). They present an overview of the nature and modes of action of helper components in the major virus clades of non-circulative viruses (Potyviruses and Caulimoviruses). Authors then detail recent advances, to which they have significantly contributed, showing that the helper strategy also appears widespread in circulative transmission categories (Tenuiviruses, Nanoviruses). 

In an extensive perspective section, they raise the question of the evolutionary significance of the existence of HC in numerous unrelated viruses, transmitted by unrelated vectors through different mechanisms. They explore the hypothesis that the helper strategy evolved several times independently in distinct viral clades and for different reasons. In particular, they present several potential benefits of plant virus HC related to virus cooperation, collective transmission and effector-driven infectivity.

As pointed out by both reviewers, this is a very clear and synthetic review. Di Mattia et al. present an exhaustive overview of virus HC-vector molecular interactions and address functionally and evolutionarily important questions. This review should benefit a large audience interested in host-virus interactions and transmission processes.

REFERENCES

(1) Ng JCK, Falk BW (2006) Virus-Vector Interactions Mediating Nonpersistent and Semipersistent Transmission of Plant Viruses. Annual Review of Phytopathology, 44, 183–212. https://doi.org/10.1146/annurev.phyto.44.070505.143325

(2) Di Mattia J, Zeddam J-L, Uzest M, Blanc S (2023) The helper strategy in vector-transmission of plant viruses. Zenodo, ver. 2 peer-reviewed and recommended by Peer Community In Infections. https://doi.org/10.5281/zenodo.7709290

Effects of the seasonal variations on within-host parasitaemia are still not well understood and potentially due to numerous factors, e.g. host and parasite species, host sex or age, or geographical regions. In this study, over three years in Switzerland, Pigeault et al. (2024) collected data on great tits reproductive outputs – laying date, clutch size, fledging success – to determine whether they were associated with avian Plasmodium parasitaemia before (winter), during (spring) and after (autumn) the breeding season. They focused on two lineages from two species: a highly generalist lineage Plasmodium relictum (lineage SGS1; Bensch et al. 2009) and a more specialized lineage Plasmodium homonucleophilum (lineage SW2). As previously found, they showed that parasitaemia level is low during the winter and then increase in spring (Applegate, 1970; Applegate 1971). Spring recurrences have been intensively studied but are still not well understood since many non-exclusive factors can provoke them, i.e environmental stressors, reproductive hormones, co-infections or bites of mosquitoes (Cornet et al. 2014).

Interestingly, the parasitaemia level during the winter before and during the breeding season were not associated to the reproductive success, meaning that birds in their populations with low parasitaemia during the winter had not more fledglings than the ones with a higher parasitaemia. However, the individuals who invested the most in the reproduction with a higher number of fledglings had also a higher parasitaemia in the following autumn. The number of laid eggs was not associated with the parasitaemia during the following autumn, showing that the initial investment in the reproduction is less important than the parental care (e.g. chicks feeding) in terms of mid/long term cost. The originality here is that authors followed populations during three periods of the year, which is not an easy task and rarely done in natural populations. Their results highlight the mid/long-term effect of higher resource allocation into reproduction on individuals’ immune system and ability to control parasite replication. Further analyses on various lineages and bird populations from other geographical regions (i.e. different latitudes) would be the next relevant step.

References

Applegate JE (1971) Spring relapse of Plasmodium relictum infections in an experimental field population of English sparrows (Passer domesticus). Journal of Wildlife Diseases, 7, 37–42. https://doi.org/10.7589/0090-3558-7.1.37

Applegate JE, Beaudoin RL (1970) Mechanism of spring relapse in avian malaria: Effect of gonadotropin and corticosterone. Journal of Wildlife Diseases, 6, 443–447. https://doi.org/10.7589/0090-3558-6.4.443

Bensch S, Hellgren O, Pérez‐Tris J (2009) MalAvi: a public database of malaria parasites and related haemosporidians in avian hosts based on mitochondrial cytochrome b lineages. Molecular Ecology Resources, 9, 1353-1358. https://doi.org/10.1111/j.1755-0998.2009.02692.x

Cornet S, Nicot A, Rivero A, Gandon S (2014) Evolution of plastic transmission strategies in avian malaria. PLoS Pathogens, 10, e1004308. https://doi.org/10.1371/journal.ppat.1004308

Pigeault R, Cozzarolo CS, Wassef J, Gremion J, Bastardot M, Glaizot O, Christe P (2024) Spring reproductive success influences autumnal malarial load in a passerine bird. bioRxiv ver 3. Peer reviewed and recommended by Peer Community In Infections. https://doi.org/10.1101/2023.07.28.550923