GloPID-R report on chikungunya, o\u27nyong-nyong and Mayaro virus, part 5: Entomological aspects

The GloPID-R (Global Research Collaboration for Infectious Disease Preparedness) chikungunya (CHIKV), o\u27nyong-nyong (ONNV) and Mayaro virus (MAYV) Working Group has been established to investigate natural history, epidemiology and clinical aspects of infection by these viruses. Here, we present a report dedicated to entomological aspects of CHIKV, ONNV and MAYV. Recent global expansion of chikungunya virus has been possible because CHIKV established a transmission cycle in urban settings using anthropophilic vectors such as Aedes albopictus and Aedes aegypti. MAYV and ONNV have a more limited geographic distribution, being confined to Africa (ONNV) and central-southern America (MAYV). ONNV is probably maintained through an enzootic cycle that has not been characterized yet, with Anopheles species as main vectors and humans as amplification hosts during epidemics. MAYV is transmitted by Haemagogus species in an enzootic cycle using non-human primates as the main amplification and maintenance hosts, and humans becoming sporadically infected when venturing in or nearby forest habitats. Here, we focused on the transmission cycle and natural vectors that sustain circulation of these viruses in their respective locations. The knowledge of the natural ecology of transmission and the capacity of different vectors to transmit these viruses is crucial to understand CHIKV emergence, and to assess the risk that MAYV and ONNV will expand on wide scale using anthropophilic mosquito species not normally considered primary vectors. Finally, the experts identified knowledge gaps and provided adapted recommendations, in order to address future entomological investigations in the right direction

Determinants of Fine-Scale Heterogeneity in Mosquito-Borne Virus Systems

ABSTRACT Arthropod-borne viruses (arboviruses) are the etiological agents of much morbidity and mortality, especially in low- and middle-income countries. Many of these viruses are spread and maintained by mosquitoes, particularly the urban mosquito Aedes aegypti. Zika virus (ZIKV) is responsible for one of the largest vector-borne disease outbreaks in the past decade, affecting millions in Central and South America including a wave of microcephaly among newborns. Mayaro virus (MAYV) is a mosquito-borne virus endemic to South America and is predicted to become an emergent public health threat. Describing the vector-virus transmission systems are critical for understanding the potential spread of these viruses. Traditionally, laboratory vector competence measures are used to evaluate the ability of a species of mosquito to take up and subsequently transmit an arbovirus by exposing mosquitoes to virus and terminally sampling for the presence of virus in the saliva or peripheral tissues at predetermined time points. However, traditional measures do not assess critical vector-virus interactions that will ultimately impact transmission potential, as these measures focus solely on rates of infectious mosquitoes. My overarching hypothesis is that there are undescribed sources of fine-scale heterogeneity within the vector-virus transmission system that will alter transmission potential. To test this hypothesis, I 1) investigated the impact of the age structure of the mosquito population on the transmission potential of ZIKV by Aedes aegypti, 2) developed a novel method for the quantification of observed heterogeneity among individual mosquitoes, and 3) characterized genotypic diversity among strains of MAYV and the potential impacts on vector competence measurements

One-Step reverse transcriptase PCR for detection of arboviruses in serum samples of patients assisted in Basic health Units in the State of Maranhão, Brazil / PCR de transcriptase reversa em uma etapa para detecção de arbovírus em amostras de soro de pacientes atendidos em Unidades Básicas de Saúde no estado do Maranhão, Brasil

polymerase chain reaction to detect acute infections caused by dengue, zika, chikungunya, and mayaro virus in clinical samples. Methods: We evaluated 620 sera samples collected from March 2016 to March 2018 and provided by the Central Health Laboratory of Maranhão (LACEN-MA). Total RNA was isolated from clinical specimens and used as the template for one-step RT-PCR assays with specific-primers designed for this study. Results: Of the 620 sera evaluated, 386 (62.2%) were positive, among them 330 (85.5%) amplified a specific fragment for chikungunya, 55 (14.2%) showed a fragment compatible with dengue serotype 4, and 1 (0.3%) exhibited profile for mayaro virus. Conclusions: The results obtained here were more sensitive than IgM-ELISA because the viral RNA was detected in serum samples from patients, not only from 1 to 6 days but also from 7 to 10 days after the beginning of clinical signs (convalescent period). Besides, the mayaro virus was detected in one serum sample that was IgM-ELISA negative for dengue, zika, and chikungunya. 

Silent circulation of Chikungunya virus among pregnant women and newborns in the Western Brazilian Amazon before the first outbreak of chikungunya fever

The prevalence of immunity to Chikungunya virus (CHIKV) in pregnant women and newborns in the Western Brazilian Amazon was assessed at a time when previous studies did not report chikungunya fever in the area. In 435 asymptomatic pregnant women and 642 healthy unrelated newborns, the presence of IgM and IgG antibodies to CHIKV were determined by a commercial ELISA. All participants were negative to IgM anti-CHIKV. Anti-CHIKV IgG was identified in 41 (9.4%) pregnant women and 66 (10.3%) newborns. The presence of anti-CHIKV IgG was positively associated with the lowest socioeconomic status in pregnant women (OR 2.54, 95% CI 1.15-5.62, p=0.021) and in the newborns’ mothers (OR 5.10, 95% CI 2.15-12.09, p< 0.001). Anti-CHIKV IgG was also associated with maternal age in both, the pregnant women (OR 1.06, 95% CI 1.00-1.11, p=0.037) and the newborns’mothers (OR 1.08, 95% CI 1.03-1.12, p=0.001). Pregnancy outcomes in which the mother or the newborn was anti-CHIKV IgG positive proceeded normally. Negative CHIKV serology was associated with being positive for DENV antibodies and having had malaria during pregnancy. These findings showed that there was already a silent circulation of CHIKV in this Amazon region before the first outbreak of chikungunya fever. Furthermore, seropositivity for CHIKV was surprisingly frequent (10%) in both, pregnant women and newborns, affecting mainly low-income women

A novel live-attenuated vaccine candidate for mayaro Fever.

Mayaro virus (MAYV) is an emerging, mosquito-borne alphavirus that causes a dengue-like illness in many regions of South America, and which has the potential to urbanize. Because no specific treatment or vaccine is available for MAYV infection, we capitalized on an IRES-based approach to develop a live-attenuated MAYV vaccine candidate. Testing in infant, immunocompetent as well as interferon receptor-deficient mice demonstrated a high degree of attenuation, strong induction of neutralizing antibodies, and efficacy against lethal challenge. This vaccine strain was also unable to infect mosquito cells, a major safety feature for a live vaccine derived from a mosquito-borne virus. Further preclinical development of this vaccine candidate is warranted to protect against this important emerging disease

Untargeted Alternative Routes of Arbovirus Transmission

Arboviruses have become global threats. Common to Dengue, Zika, yellow fever, chikungunya, and Mayaro viruses is their ability to be transmitted by mosquitoes. Several strategies based on transgenics or microbiology are currently being field-tested. While this approach seems hopeful, the research community needs to focus on potential backlash from these technologies to prevent failure. The aim of the Special Issue is to cover different transmission routes that are untargeted by the newly developed strategies to foresee limitations. Here, Fontenille & Powell gave their insights on how a mosquito species becomes a global vector, Yen & Failloux presented the limitations of Wolbachia-based population replacement, Pereira-dos-Santos et al. reviewed the evidence that Aedes albopictus is an important vector, and Diagne et al. gathered information about the latest emerging arbovirus: Mayaro. Manuel et al. demonstrated that in certain conditions mosquitoes efficiently transmit Zika viruses and Rozo-Lopez et al. showed that midges vertically transmit stomatitis virus, highlighting the epidemiological significance of vertical transmission. Vector competence for secondary vectors was improved by Kosoltanapiwat et al. during entomological surveillance and by Fernandes et al. when evaluating different vector species competence for Zika viruses. Morales-Vargas et al. and Calvez et al. improved our understanding of DENV2 and DENV4 epidemiology

Molecular epidemiological investigation of Mayaro virus in febrile patients from Goiania City, 2017-2018.

Mayaro virus (MAYV) has historically been associated with sylvatic transmission; however, urban outbreaks have been reported in Brazil, including cases of co-detection with dengue virus (DENV). Therefore, we performed a molecular survey to investigate MAYV circulation and cocirculation with DENV within Goiania, a major city in Central-West Brazil. Among 375 subjects with arbovirus-like symptoms, 259 were positive for DENV and 26 for MAYV. Of these, 17 were coinfected with DENV-2, suggesting co-transmission of the viruses. The most common complaints at the time of inclusion were myalgia, headache, fever, arthralgia, retro-orbital pain, and skin rash. No specific symptoms were associated with MAYV when either detected alone or co-detected with DENV, compared to that when DENV was detected alone. Most MAYV-infected subjects were women with no recent travel history to rural/sylvatic areas. Phylogenetic reconstruction indicated that the MAYV identified in this study is closely related with a lineage observed in Peru, belonging to genotype D. Our results corroborate the growing circulation of MAYV in urban environments in Brazil and reinforce the need to implement laboratory diagnosis in the Unified Health System, considering that the clinical manifestations of Mayaro fever are similar to those of other arboviruses, particularly dengue. Furthermore, most cases occurred in association with DENV-2. Further phylogenetic studies are needed to evaluate MAYV, which has not been widely examined

A silent public health threat: emergence of Mayaro virus and co-infection with Dengue in Peru

Objective: To describe frequency and clinical characteristics of MAYV infection in Piura, as well as the association of this pathogen with DENV. Results: A total of 86/496 (17.3%) cases of MAYV were detected, of which 54 were MAYV mono-infection and 32 were co-infection with DENV, accounting for 10.9% and 6.4%, respectively. When evaluating monoinfection by MAYV the main groups were 18–39 and 40–59 years old, with 25.9% and 20.4% respectively. Co-infections were more common in the age group 18–39 and those > 60 years old, with 34.4% and 21.9%, respectively. The most frequent clinical presentation were headaches (94.4%, 51/54) followed by arthralgias (77.8%, 42/54). During the 8-month study period the most cases were identified in the months of May (29.1%) and June (50.0%).National Research Foundation of KoreaRevisión por pare