Viral co-infection with dengue and H1N1 virus in a critical care setting

Addressing the Dual Threat of Dengue and Influenza in Bangladesh: A Perspective on the Prevention and Preparedness Strategies

Background and Aim

In Bangladesh, dengue fever and influenza pose serious public health risks due to their high rates of morbidity and fatality. Frequent outbreaks have been caused by dengue, a virus spread by mosquitoes that causes flu-like symptoms, particularly during the monsoon season. Another infectious respiratory illness that varies every year is influenza. Both illnesses frequently co-circulate in tropical areas like Bangladesh, raising the possibility of co-infection and putting vulnerable groups at higher risk. The purpose of the article is to explore the effects of dengue and influenza co-infection in Bangladesh, looking at present issues and possible solutions to this dual health burden.

Methodology

This perspective piece gathers data from authoritative sources, including PubMed, the World Health Organization, Directorate General of Health Services, Ministry of Health and Family Welfare, Bangladesh, and the European Center for Disease Prevention and Control. Relevant literature on dengue and influenza incidence, control measures, and co-infection dynamics was reviewed.

Discussion

In Bangladesh, dengue incidence are still on the rise, while influenza infections have climbed, especially during the winter. The country's healthcare system may be overburdened by the simultaneous spread of both diseases, particularly if dengue rates keep rising and influenza cases rise. To lessen the effects of these illnesses, effective community awareness campaigns, vector control initiatives, and early diagnosis techniques are crucial.

Conclusion

Bangladesh must emphasize increased preventative and preparation measures, such as better monitoring, public health communication, and vaccine development research, given the twin danger posed by dengue and influenza. To lower the likelihood of co-infection and avert future public health emergencies, coordinated actions are essential.

Prior influenza virus infection alleviates an arbovirus encephalitis by reducing viral titer, inflammation, and cellular infiltrates in the central nervous system

Respiratory and encephalitic virus infections represent a significant risk to public health globally. Detailed investigations of immunological responses and disease outcomes during sequential virus infections are rare. Here, we define the impact of influenza virus infection on a subsequent virus encephalitis. We used a model system in which mice were given influenza A virus (IAV) infection 8 days prior to Semliki Forest virus (SFV) infection (IAV→SFV). IAV infection clearly attenuated the subsequent SFV infection with reduced titers of infectious SFV and lower levels of cytokines and chemokines in the central nervous system (CNS). In contrast, the SFV viremia in both IAV→SFV and SFV-only mice was comparable. Increased type I interferon (IFN) levels in the CNS after IAV infection might have contributed to some level of protection towards SFV infection in the CNS, suggesting that early control of SFV replication in the CNS during IAV→SFV infection led to reduced adaptive response, given the lower number of CD8+ T cells recruited to the brain in IAV→SFV infection. In lungs, however, prior IAV infection elicited effector CD8+ T cells with highly activated CD38 and/or CD25 phenotypes, while SFV-only infection elicited distinct effector CD8+ T cells with increased frequencies of KLRG1 expression, a hallmark of short-lived effector T cells. Taken together, our findings demonstrate that prior IAV infection can confer protective immunity toward secondary SFV infection, confirmed by reduced disease severity and inflammatory immune responses in the brain. Our work provides important insights into therapies and vaccine regimens directed against unrelated pathogens.

IMPORTANCE

Influenza viruses are medically important human pathogens that caused epidemics and pandemics throughout history. Conversely, encephalitic arthropod-borne virus (arboviral) diseases affect both humans and domestic animals, creating massive public health issues. Influenza viruses circulate globally while arboviruses dominate tropical regions. Given both influenza virus and encephalitic arboviruses, such as alphaviruses, circulate in many regions globally, co-infections are likely to occur. In addition, arthropod-borne neurotropic infections are generally mild or asymptomatic, hence are likely to be unnoticed as a risk factor during influenza infection. However, the consequences of such co-infections are unclear. Our recent study showed that alphavirus infection preceding Influenza A virus (IAV) infection negatively impacted immune responses to the influenza virus in mice. Here, we aim to investigate the immune responses when the order of sequential infection with IAV and alphavirus are swapped. Altogether, our findings will provide key insights to improved diagnostics, preventative vaccines, and antiviral therapies.

Comparison of clinical and virological features in pediatric and adult dengue cases at Insein General Hospital during Myanmar's 2022 dengue season

BACKGROUND

Myanmar is one of the countries in Southeast Asia where serious dengue outbreaks occur and Yangon is among the regions with the highest number of cases in the country. Many infections including dengue are common in Yangon during the rainy season, and co-infections may also occur. Adults are more likely than children to experience co-infections of dengue and other diseases. Although pediatric dengue has been studied in Yangon for decades, research on adult dengue is scant. Therefore, this study compared the clinical and virological characteristics of pediatric and adult dengue cases in Yangon.

METHODS

This cross-sectional study was conducted at Insein General Hospital in Yangon, Myanmar, from June to September 2022. We recruited 221 suspected dengue patients (134 children and 87 adults), with or without other diseases, and tested their dengue serological markers using a serological method and their dengue virus (DENV) serotypes using conventional RT-PCR. Chi-squared and Fisher's exact tests were conducted to assess significance.

RESULTS

The dengue non-structural protein-1 antigen (NS1Ag) positivity was 37% in children and 32% in adults. DENV serotypes were identified in 80% of NS1Ag-positive patients. Among NS1Ag-positive cases, the DENV-1 serotype predominated (67%), followed by DENV-2 (17%), DENV-3 (9%), DENV-4 (5%), and mixed DENV-1 and DENV-2 (2%) serotypes. Shock was observed in 14% of children and 3% of adults. Anti-dengue IgG antibody positivity was positively correlated with dengue shock. Three pediatric dengue cases (6%) also had other infections including bronchiolitis, ear infection, and diarrhea. Seven adult dengue cases (25%) also had other diseases including advanced HIV infection, severe pneumonia, tonsillitis, thyroid disease, cholecystitis, drug poisoning, and thalassemia.

CONCLUSION

The serotype distribution and clinical presentations of pediatric and adult dengue cases were not significantly different, but adults were more likely to have dengue together with other diseases than children. This study provides information for the better management of febrile children and adults in hospital settings and provides a foundation for nationwide epidemiological studies on dengue serotypes and modifications of the national guidelines for dengue management in Myanmar.

Prior infection with unrelated neurotropic virus exacerbates influenza disease and impairs lung T cell responses

Immunity to infectious diseases is predominantly studied by measuring immune responses towards a single pathogen, although co-infections are common. In-depth mechanisms on how co-infections impact anti-viral immunity are lacking, but are highly relevant to treatment and prevention. We established a mouse model of co-infection with unrelated viruses, influenza A (IAV) and Semliki Forest virus (SFV), causing disease in different organ systems. SFV infection eight days before IAV infection results in prolonged IAV replication, elevated cytokine/chemokine levels and exacerbated lung pathology. This is associated with impaired lung IAV-specific CD8+ T cell responses, stemming from suboptimal CD8+ T cell activation and proliferation in draining lymph nodes, and dendritic cell paralysis. Prior SFV infection leads to increased blood brain barrier permeability and presence of IAV RNA in brain, associated with increased trafficking of IAV-specific CD8+ T cells and establishment of long-term tissue-resident memory. Relative to lung IAV-specific CD8+ T cells, brain memory IAV-specific CD8+ T cells have increased TCR repertoire diversity within immunodominant DbNP366+CD8+ and DbPA224+CD8+ responses, featuring suboptimal TCR clonotypes. Overall, our study demonstrates that infection with an unrelated neurotropic virus perturbs IAV-specific immune responses and exacerbates IAV disease. Our work provides key insights into therapy and vaccine regimens directed against unrelated pathogens.

Dengue Hemorrhagic Fever: A State-of-the-Art Review Focused in Pulmonary Involvement

Dengue fever is an arboviral disease transmitted to humans through the bites of infected female Aedes mosquitoes. Dengue virus is a member of the Flaviviridae family, and human infection can be caused by any of the four antigenically distinct serotypes (DENV 1–4). The infection has become recognized as the most important and prevalent arboviral disease in humans, endemic in almost 100 countries worldwide. Nearly 3 billion people live in areas with transmission risk. Autochthonous transmission of the virus in previously disease-free areas, increased incidence in endemic areas, and epidemic resurgence in controlled regions could increase the risk of contracting more severe forms of the disease, such as dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Symptomatic dengue virus infection can present with a wide range of clinical manifestations, from mild fever to life-threatening DSS. Thoracic complications may manifest as pleural effusion, pneumonitis, non-cardiogenic pulmonary edema, and hemorrhage/hemoptysis. No vaccine is currently available and no specific treatment for dengue fever exists, but prevention and prompt management of complications in patients with DHF can help reduce mortality. This review describes the main clinical, pathological, and imaging findings of thoracic involvement in DHF.

Influenza and dengue virus co-infection impairs monocyte recruitment to the lung, increases dengue virus titers, and exacerbates pneumonia

Co-infections of influenza virus and bacteria are known to cause severe disease, but little information exists on co-infections with other acute viruses. Seasonal influenza and dengue viruses (DENV) regularly co-circulate in tropical regions. The pandemic spread of influenza virus H1N1 (hereafter H1N1) in 2009 led to additional severe disease cases that were co-infected with DENV. Here, we investigated the impact of co-infection on immune responses and pathogenesis in a new mouse model. Co-infection of otherwise sublethal doses of a Nicaraguan clinical H1N1 isolate and two days later with a virulent DENV2 strain increased systemic DENV titers and caused 90% lethality. Lungs of co-infected mice carried both viruses, developed severe pneumonia, and expressed a unique pattern of host mRNAs, resembling only partial responses against infection with either virus alone. A large number of monocytes were recruited to DENV-infected but not to co-infected lungs, and depletion and adoptive transfer experiments revealed a beneficial role of monocytes. Our study shows that co-infection with influenza and DENV impairs host responses, which fail to control DENV titers and instead, induce severe lung damage. Further, our findings identify key inflammatory pathways and monocyte function as targets for future therapies that may limit immunopathology in co-infected patients.