Acute flaccid paralysis incidence and Zika virus surveillance, Pacific Islands

Dengue Virus and Zika Virus Seroprevalence in the South Pacific Populations of the Cook Islands and Vanuatu

Arboviral diseases are serious threats to global health with increasing prevalence and potentially severe complications. Significant arthropod-borne viruses are the dengue viruses (DENV 1-4), the Zika virus (ZIKV), and the chikungunya virus (CHIKV). Among the areas most affected is the South Pacific Region (SPR). Here, arboviruses not only cause a high local burden of disease, but the region has also proven to contribute to their global spread. Outpatient serum samples collected between 08/2016 and 04/2017 on three islands of the island states of Vanuatu and the Cook Islands were tested for anti-DENV- and anti-ZIKV-specific antibodies (IgG) using enzyme-linked immunosorbent assays (ELISA). ELISA test results showed 89% of all test sera from the Cook Islands and 85% of the Vanuatu samples to be positive for anti-DENV-specific antibodies. Anti-ZIKV antibodies were identified in 66% and 52%, respectively, of the test populations. Statistically significant differences in standardized immunity levels were found only at the intranational level. Our results show that in both the Cook Islands and Vanuatu, residents were exposed to significant Flavivirus transmission. Compared to other seroprevalence studies, the marked difference between ZIKV immunity levels and previously published CHIKV seroprevalence rates in our study populations is surprising. We propose the timing of ZIKV and CHIKV emergence in relation to recurrent DENV outbreaks and the impact of seasonality as explanatory external factors for this observation. Our data add to the knowledge of arboviral epidemics in the SPR and contribute to a better understanding of virus spread, including external conditions with potential influence on outbreak dynamics. These data may support preventive and rapid response measures in the affected areas, travel-related risk assessment, and infection identification in locals and returning travelers.

Clinical manifestations of dengue, Zika and chikungunya in the Pacific Islands: A systematic review and meta-analysis

Dengue, Zika and chikungunya outbreaks pose a significant public health risk to Pacific Island communities. Differential diagnosis is challenging due to overlapping clinical features and limited availability of laboratory diagnostic facilities. There is also insufficient information regarding the complications of these arboviruses, particularly for Zika and chikungunya. We conducted a systematic review and meta-analysis to calculate pooled prevalence estimates with 95% confidence intervals (CI) for the clinical manifestations of dengue, Zika and chikungunya in the Pacific Islands. Based on pooled prevalence estimates, clinical features that may help to differentiate between the arboviruses include headache, haemorrhage and hepatomegaly in dengue; rash, conjunctivitis and peripheral oedema in Zika; and the combination of fever and arthralgia in chikungunya infections. We estimated that the hospitalisation and mortality rates in dengue were 9.90% (95% CI 7.67-12.37) and 0.23% (95% CI 0.16-0.31), respectively. Severe forms of dengue occurred in 1.92% (95% CI 0.72-3.63) of reported cases and 23.23% (95% CI 13.58-34.53) of hospitalised patients. Complications associated with Zika virus included Guillain-Barré syndrome (GBS), estimated to occur in 14.08 (95% CI 11.71-16.66) per 10,000 reported cases, and congenital brain malformations such as microcephaly, particularly with first trimester maternal infection. For chikungunya, the hospitalisation rate was 2.57% (95% CI 1.30-4.25) and the risk of GBS was estimated at 1.70 (95% CI 1.06-2.48) per 10,000 reported cases. Whilst ongoing research is required, this systematic review enhances existing knowledge on the clinical manifestations of dengue, Zika and chikungunya infections and will assist Pacific Island clinicians during future arbovirus outbreaks.

Seroprevalence of dengue, Zika, chikungunya and Ross River viruses across the Solomon Islands

Across the Pacific, and including in the Solomon Islands, outbreaks of arboviruses such as dengue, chikungunya, and Zika are increasing in frequency, scale and impact. Outbreaks of mosquito-borne disease have the potential to overwhelm the health systems of small island nations. This study mapped the seroprevalence of dengue, Zika, chikungunya and Ross River viruses in 5 study sites in the Solomon Islands. Serum samples from 1,021 participants were analysed by ELISA. Overall, 56% of participants were flavivirus-seropositive for dengue (28%), Zika (1%) or both flaviviruses (27%); and 53% of participants were alphavirus-seropositive for chikungunya (3%), Ross River virus (31%) or both alphaviruses (18%). Seroprevalence for both flaviviruses and alphaviruses varied by village and age of the participant. The most prevalent arboviruses in the Solomon Islands were dengue and Ross River virus. The high seroprevalence of dengue suggests that herd immunity may be a driver of dengue outbreak dynamics in the Solomon Islands. Despite being undetected prior to this survey, serology results suggest that Ross River virus transmission is endemic. There is a real need to increase the diagnostic capacities for each of the arboviruses to support effective case management and to provide timely information to inform vector control efforts and other outbreak mitigation interventions.

The occurrence of arboviruses is increasing and causing significant impacts on human health. This is of high concern in small Pacific island nations where fragile health systems are regularly overwhelmed by disease outbreaks. To effectively prevent and control disease transmission there is a need to understand which viruses have been in circulation. Therefore, we conducted a cross-sectional survey of residents from 5 study sites distributed across the Solomon Islands. The serum samples were tested for antibodies that indicate prior infection for four arboviruses. We found evidence that the residents of the Solomon Islands have been exposed to substantial transmission of dengue and Ross River viruses, with lower levels of Zika and chikungunya transmission. Two large dengue outbreaks have been recently experienced and the outbreak pattern suggests that natural herd immunity may still be a driver of dengue outbreak dynamics in the Solomon Islands. Regarding Ross River virus, transmission is endemic despite being undetected prior to this survey. There is a real need to increase the capacity to accurately diagnose each of these arboviruses to support effective case management and to provide timely information to inform vector control efforts.

Arboviral Disease Outbreaks in the Pacific Islands Countries and Areas, 2014 to 2020: A Systematic Literature and Document Review

Arthropod-borne diseases pose a significant public health threat, accounting for greater than 17% of infectious disease cases and 1 million deaths annually. Across Pacific Island countries and areas (PICs), outbreaks of dengue, chikungunya, and Zika are increasing in frequency and scale. Data about arbovirus outbreaks are incomplete, with reports sporadic, delayed, and often based solely on syndromic surveillance. We undertook a systematic review of published and grey literature and contacted relevant regional authorities to collect information about arboviral activity affecting PICs between October 2014 and June 2020. Our literature search identified 1176 unique peer-reviewed articles that were reduced to 25 relevant publications when screened. Our grey literature search identified 873 sources. Collectively, these data reported 104 unique outbreaks, including 72 dengue outbreaks affecting 19 (out of 22) PICs, 14 chikungunya outbreaks affecting 11 PICs, and 18 Zika outbreaks affecting 14 PICs. Our review is the most complete account of arboviral outbreaks to affect PICs since comparable work was published in 2014. It highlights the continued elevated level of arboviral activity across the Pacific and inconsistencies in how information about outbreaks is reported and recorded. It demonstrates the importance of a One-Health approach and the role that improved communication and reporting between different governments and sectors play in understanding the emergence, circulation, and transboundary risks posed by arboviral diseases.

Network of Interactions between ZIKA Virus Non-Structural Proteins and Human Host Proteins

The Zika virus (ZIKV) is a mosquito-borne Flavivirus and can be transmitted through an infected mosquito bite or through human-to-human interaction by sexual activity, blood transfusion, breastfeeding, or perinatal exposure. After the 2015-2016 outbreak in Brazil, a strong link between ZIKV infection and microcephaly emerged. ZIKV specifically targets human neural progenitor cells, suggesting that proteins encoded by ZIKV bind and inactivate host cell proteins, leading to microcephaly. Here, we present a systematic annotation of interactions between human proteins and the seven non-structural ZIKV proteins corresponding to a Brazilian isolate. The interaction network was generated by combining tandem-affinity purification followed by mass spectrometry with yeast two-hybrid screens. We identified 150 human proteins, involved in distinct biological processes, as interactors to ZIKV non-structural proteins. Our interacting network is composed of proteins that have been previously associated with microcephaly in human genetic disorders and/or animal models. Further, we show that the protein inhibitor of activated STAT1 (PIAS1) interacts with NS5 and modulates its stability. This study builds on previously published interacting networks of ZIKV and genes related to autosomal recessive primary microcephaly to generate a catalog of human cellular targets of ZIKV proteins implicated in processes related to microcephaly in humans. Collectively, these data can be used as a resource for future characterization of ZIKV infection biology and help create a basis for the discovery of drugs that may disrupt the interaction and reduce the health damage to the fetus.

A systematic review and evaluation of Zika virus forecasting and prediction research during a public health emergency of international concern

INTRODUCTION

Epidemic forecasting and prediction tools have the potential to provide actionable information in the midst of emerging epidemics. While numerous predictive studies were published during the 2016-2017 Zika Virus (ZIKV) pandemic, it remains unknown how timely, reproducible, and actionable the information produced by these studies was.

METHODS

To improve the functional use of mathematical modeling in support of future infectious disease outbreaks, we conducted a systematic review of all ZIKV prediction studies published during the recent ZIKV pandemic using the PRISMA guidelines. Using MEDLINE, EMBASE, and grey literature review, we identified studies that forecasted, predicted, or simulated ecological or epidemiological phenomena related to the Zika pandemic that were published as of March 01, 2017. Eligible studies underwent evaluation of objectives, data sources, methods, timeliness, reproducibility, accessibility, and clarity by independent reviewers.

RESULTS

2034 studies were identified, of which n = 73 met the eligibility criteria. Spatial spread, R0 (basic reproductive number), and epidemic dynamics were most commonly predicted, with few studies predicting Guillain-Barré Syndrome burden (4%), sexual transmission risk (4%), and intervention impact (4%). Most studies specifically examined populations in the Americas (52%), with few African-specific studies (4%). Case count (67%), vector (41%), and demographic data (37%) were the most common data sources. Real-time internet data and pathogen genomic information were used in 7% and 0% of studies, respectively, and social science and behavioral data were typically absent in modeling efforts. Deterministic models were favored over stochastic approaches. Forty percent of studies made model data entirely available, 29% provided all relevant model code, 43% presented uncertainty in all predictions, and 54% provided sufficient methodological detail to allow complete reproducibility. Fifty-one percent of predictions were published after the epidemic peak in the Americas. While the use of preprints improved the accessibility of ZIKV predictions by a median of 119 days sooner than journal publication dates, they were used in only 30% of studies.

CONCLUSIONS

Many ZIKV predictions were published during the 2016-2017 pandemic. The accessibility, reproducibility, timeliness, and incorporation of uncertainty in these published predictions varied and indicates there is substantial room for improvement. To enhance the utility of analytical tools for outbreak response it is essential to improve the sharing of model data, code, and preprints for future outbreaks, epidemics, and pandemics.

Organisation of primary health care in the Asia-Pacific region: developing a prioritised research agenda

Health system planners in low- and middle-income countries (LMIC) of the Asia-Pacific region seeking to reorient primary health care (PHC) systems to achieve universal health coverage may be hindered by lack of knowledge of what works in their setting. With limited resources for research available, it is important to identify evidence-based strategies for reorganising PHC delivery, determine where relevant evidence gaps exist and prioritise these for future study. This paper describes an approach for doing this using the best available evidence combined with consultation to establish evidence priorities. We first reviewed PHC organisational interventions in Asia-Pacific LMICs and ascertained evidence gaps. The largest gaps related to interventions to promote access to essential medicines, patient management tools, effective health promotion strategies and service planning and accountability. Evidence from Pacific Island countries was particularly scant. We then engaged an expert panel of 22 PHC stakeholders from seven Asia-Pacific LMICs in a Delphi exercise to identify priority questions for future research. Research priorities were: (1) identifying effective PHC service delivery models for chronic diseases; (2) devising sustainable models of disease integration; (3) optimising task shifting; (4) understanding barriers to care continuity; (5) projecting future PHC needs; and (6) designing appropriate PHC service packages. Notably, stakeholder-determined priorities reflected large, context-dependent system issues, while evidence gaps centred on discrete interventions. Future research on the organisation of PHC services in Asia-Pacific LMICs should incorporate codesign principles to engage researchers and national PHC system stakeholders, and innovative methods that build on existing evidence and account for system complexity.

Epidemic surveillance in a low resource setting: lessons from an evaluation of the Solomon Islands syndromic surveillance system, 2017

Background

Solomon Islands is one of the least developed countries in the world. Recognising that timely detection of outbreaks is needed to enable early and effective response to disease outbreaks, the Solomon Islands government introduced a simple syndromic surveillance system in 2011. We conducted the first evaluation of the system and the first exploration of a national experience within the broader multi-country Pacific Syndromic Surveillance System to determine if it is meeting its objectives and to identify opportunities for improvement.

Methods

We used a multi-method approach involving retrospective data collection and statistical analysis, modelling, qualitative research and observational methods.

Results

We found that the system was well accepted, highly relied upon and designed to account for contextual limitations. We found the syndromic algorithm used to identify outbreaks was moderately sensitive, detecting 11.8% (IQR: 6.3–25.0%), 21.3% (IQR: 10.3–36.8%), 27.5% (IQR: 12.8–52.3%) and 40.5% (IQR: 13.5–65.7%) of outbreaks that caused small, moderate, large and very large increases in case presentations to health facilities, respectively. The false alert rate was 10.8% (IQR: 4.8–24.5%). Rural coverage of the system was poor. Limited workforce, surveillance resourcing and other ‘upstream’ health system factors constrained performance.

Conclusions

The system has made a significant contribution to public health security in Solomon Islands, but remains insufficiently sensitive to detect small-moderate sized outbreaks and hence should not be relied upon as a stand-alone surveillance strategy. Rather, the system should sit within a complementary suite of early warning surveillance activities including event-based, in-patient- and laboratory-based surveillance methods. Future investments need to find a balance between actions to address the technical and systems issues that constrain performance while maintaining simplicity and hence sustainability.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-6295-7) contains supplementary material, which is available to authorized users.

Differentiation enhances Zika virus infection of neuronal brain cells

Zika virus (ZIKV) is an emerging, mosquito-borne pathogen associated with a widespread 2015–2016 epidemic in the Western Hemisphere and a proven cause of microcephaly and other fetal brain defects in infants born to infected mothers. ZIKV infections have been also linked to other neurological illnesses in infected adults and children, including Guillain-Barré syndrome (GBS), acute flaccid paralysis (AFP) and meningoencephalitis, but the viral pathophysiology behind those conditions remains poorly understood. Here we investigated ZIKV infectivity in neuroblastoma SH-SY5Y cells, both undifferentiated and following differentiation with retinoic acid. We found that multiple ZIKV strains, representing both the prototype African and contemporary Asian epidemic lineages, were able to replicate in SH-SY5Y cells. Differentiation with resultant expression of mature neuron markers increased infectivity in these cells, and the extent of infectivity correlated with degree of differentiation. New viral particles in infected cells were visualized by electron microscopy and found to be primarily situated inside vesicles; overt damage to the Golgi apparatus was also observed. Enhanced ZIKV infectivity in a neural cell line following differentiation may contribute to viral neuropathogenesis in the developing or mature central nervous system.

The Attractiveness of the Gravid Aedes Trap to Dengue Vectors in Fiji

The Gravid Aedes Trap (GAT) is a passive trap that relies on visual and olfactory cues to lure and capture gravid mosquitoes. The GAT was designed as a dengue vector surveillance tool for use in conditions where power sources are not readily available. Experiments were conducted over a 10-d period in Fiji to determine which species of mosquitoes the GAT would collect, how different infusion types affect the attractiveness of the trap, how long each infusion type took to begin attracting mosquitoes, and how long the infusion was attractive to container breeding Aedes mosquitoes. Infusions were created by adding 10 g of organic material to 2 liters of water. Infusions were made using chicken feed pellets, dried mango leaves (Mangifera indica), and dried lawn grasses (primarily Axonopus spp.). The GAT collected four different vectors Aedes aegypti (Linnaeus) (Diptera: Culicidae), Aedes albopictus (Skuse) (Diptera: Culicidae), Aedes polynesiensis Mark (Diptera: Culicidae), and Culex quinquefasciatus Say (Diptera: Culicidae). As observed in previous studies, using some type of organic infusion improved the attractiveness of the trap. Of the three different infusion components tested, chicken feed was most attractive followed by lawn grasses and mango leaves. All infusions performed better than plain water. Chicken feed was found to be most attractive for Ae. aegypti and Ae. albopictus during the first 6 d after placing the traps and for Cx. quinquifasciatus in days 7-9. The mango and grass infusions took longer to attract mosquitoes but were most attractive during days 7-10 for all species.

Zika Virus Diseases - The New Face of an Ancient Enemy as Global Public Health Emergency (2016): Brief Review and Recent Updates

Zika virus (ZIKV) disease is caused by a virus transmitted by Aedes mosquito. It presents as flu-like symptoms lasting for 5-7 days and shows potential association with neurological and autoimmune complications such as congenital microcephaly and adult paralysis disorder, Guillain-Barré syndrome. Treatment measures are conservative as the disease is self-limiting. ZIKV earlier affected several tropical regions of Africa and Asia from 1951 to 2006. Subsequently, it moved out from these regions to land as outbreaks in Yap Island, French Polynesia, South America, and most recently in Brazil. The WHO declared it as an international public health emergency in 2016 and an extraordinary event with recommendations for improving communications, tightening vigil on ZIKV infections, and improving mosquito control measures. The authors in this article aim to briefly discuss ZIKV infection, its epidemiology, clinical manifestations, management, and prevention.