Cases Of Yellow Fever Research Articles

Viral Kinetics in Sylvatic Yellow Fever Cases.

Yellow fever is a mosquito-borne zoonotic disease caused by yellow fever virus (YFV). Between 2017 and 2019, more than 504 human cases and 176 deaths were confirmed in the outskirts of São Paulo city. Throughout this outbreak, studies suggested a potential association between YFV viremia and mortality. Viral ribonucleic acid was measured using reverse-transcription quantitative polymerase chain reaction in plasma samples collected at up to 5 time points, between 3 and 120 days after symptoms onset. Eighty-four patients with confirmed YFV infection were included. Most were males, median age was 42, and 30 (36%) died. Deceased patients were older than survivors (P = .003) and had a higher viremia across all time points (P = .0006). Mean values of viremia had a positive, statistically significant correlation with peak values of neutrophils, indirect bilirubin, aspartate transaminase, international normalized ratio, and creatinine. Finally, a Cox proportional hazards model adjusted for age and laboratory variables showed that viremia is independently associated with death, with a mean 1.84-fold increase (84%) in the hazard of death (P < .001) for each unit increase in mean log10 viremia. Our results raise the importance of monitoring YFV viremia and suggest a potential benefit of antiviral drugs or neutralizing monoclonal antibodies early in the course of this infection to improve disease outcomes.

New Insights into the Mechanism of Immune-Mediated Tissue Injury in Yellow Fever: The Role of Immunopathological and Endothelial Alterations in the Human Lung Parenchyma.

Yellow fever (YF) may cause lesions in different organs. There are no studies regarding the in situ immune response in the human lung and investigating immunopathological aspects in fatal cases can help to better understand the evolution of the infection. Lung tissue samples were collected from 10 fatal cases of human yellow fever and three flavivirus-negative controls who died of other causes and whose lung parenchymal architecture was preserved. In YFV-positive fatal cases, the main histopathological changes included the massive presence of diffuse alveolar inflammatory infiltrate, in addition to congestion and severe hemorrhage. The immunohistochemical analysis of tissues in the lung parenchyma showed significantly higher expression of E-selectin, P-selectin, ICAM-1, VCAM-1 in addition to cytokines such as IL-4, IL-10, IL-13, TNF- α, IFN-γ and TGF-β compared to the negative control. The increase in immunoglobulins ICAM-1 and VCAM-1 results in strengthening of tissue transmigration signaling. E-selectin and P-selectin actively participate in this process of cell migration and formation of the inflammatory infiltrate. IFN-γ and TNF-α participate in the process of cell injury and viral clearance. The cytokines IL-4 and TGF-β, acting in synergism, participate in the process of tissue regeneration and breakdown. The anti-inflammatory cytokines IL-4, IL-10 and IL-13 also act in the reduction of inflammation and tissue repair. Our study indicates that the activation of the endothelium aggravates the inflammatory response by inducing the expression of adhesion molecules and cytokines that contribute to the rolling, recruitment, migration and eliciting of the inflammatory process in the lung parenchyma, contributing to the fatal outcome of the disease.

Occurrence of the Sylvatic Yellow Fever Vector Mosquito Haemagogus leucocelaenus (Diptera: Culicidae) in an Atlantic Forest Fragment of the Touristic State of Rio de Janeiro, Brazil.

The yellow fever virus is estimated to cause 30,000 deaths each year worldwide, with the majority of cases and deaths occurring in Africa. The virus is also endemic to Central and South America, including northern and western Brazil. The sylvatic cycle of the virus is related to wild and rural areas, with nonhuman primates as the primary host and wild mosquitoes, specifically from the genera Haemagogus, as vectors. The diversity of the mosquito community plays a significant role in the increase of pathogen transmission to humans. In the present study, we detected fluctuation in populations of vector mosquitoes using ovitraps for Culicidae egg collection. The study area is a forest fragment of the Atlantic Forest, one of the most threatened biomes in Brazil. This biome has been suffering significant deforestation due to anthropic activity. Worryingly, the proximity of human populations to forest environments increases the risk of spreading disease from forest fragments to urban areas. Our findings showed that the highest egg abundance occurred in December 2019, with a significant difference (p = 0.005) between rainy and dry seasons. Most eggs were collected during the rainy period. Subsequent quantification of specimens from epidemiologically relevant species hatched from field-collected eggs resulted in 1,131 (86%) Haemagogus leucocelaenus (Dyar & Shannon, 1924), 111 (8%) Aedes terrens (Walker, 1856), 47 (4%) Aedes albopictus (Skuse, 1894), and 21 (2%) Haemagogus janthinomys (Dyar, 1921). Finally, we assessed the behavior of different vector species performing oviposition on the same breeding site. The highest correlation coefficient was observed between Ae. albopictus and Ae. terrens (rho = 0.52) concerning other Culicidae species. Therefore, we believe that Culicidae population surveillance is crucial for disease monitoring since the increase in specimens of a number of vector species influences the emergence of yellow fever cases in nonhuman primates and human populations.

Estimation of yellow fever incidence in Togo between 2010 and 2020

BackgroundYellow fever virus is an arbovirus transmitted to humans by Aedes and Haemogogus mosquito species. To date, there is no specific treatment for yellow fever. However, an effective vaccine is available for the prevention. After a decline in yellow fever cases in Africa between 2004 and 2015, large-scale transmission of the virus was observed in Africa during 2019, with outbreaks recorded in West Africa. The objective of this study was to estimate the incidence of yellow fever cases recorded in the national reference laboratory of Togo from 2010 to 2020. MethodData were extracted from the National Institute of Hygiene database from 2010 to 2020 with an Excel sheet and descriptive analyses were performed. ResultsA total of 4350 samples were collected between 2010 and 2020 in Togo from yellow fever suspected cases. These cases had a median age of 12 years (IQR: 5–24), and 21% of them were from the Maritime region. Among them, 30 cases were reported by national laboratory, with a global incidence of 0.7% (confidence interval 95%: [0.4–1.0]). At the yellow fever regional laboratory, 14 cases were confirmed with an incidence of 0.33% (confidence interval 95%: [0.18–0.55]). In this population, 37.7% had been immunized against yellow fever. ConclusionThis study shows that Togo presents cases of yellow fever. Identification of the vectors and implementation of efficient vector control measures could help prevent this disease, as well as other diseases transmitted by the same vectors. Yellow fever vaccination should be a priority in vaccination programs.

Effects of migration and vaccination on the spread and control of yellow fever in Latin American communities: a mathematical modelling study

BackgroundWith the COVID-19 pandemic, the stigmatisation of migrants as mere vectors of diseases has worsened. Our goal was to assess how migration rates could affect yellow fever dynamics in Latin American communities, one of those being in Necoclí, Colombia, with 70 000 inhabitants and another 70 000 migrants annually waiting to access central America. MethodsThis modelling study used a susceptible, exposed, infective, recovered, and vaccinated compartimental deterministic model for humans and vectors and numerical simulations applied to three scenarios: (1) migration from an endemic community to a disease-free host community; (2) migration from an endemic community located in a migratory route to a disease-free community; and (3) Necoclí as a case study, evaluating the effects of vaccinating migrants upon arrival. FindingsThe type of vector and vaccination coverage in the host community were more relevant for the occurrence of outbreaks than migration rates, and effective vaccinations were able to reduce 55·68% of cases and 54·54% of deaths, but not eliminate them entirely because of the influx of exogenous cases. In Necolcí, assuming the number of migrants equals the resident population, the loss of herd immunity reached 50% every year, and in the case of an outbreak, there were from 3500 to almost 8000 cases of yellow fever in the city. InterpretationAlthough migration brings a virus to a community, it does not cause the outbreak outcomes. Therefore, as our results showed, the focus should be on vaccinations and working on vector control rather than blaming migrants. Vaccination could prevent even more cases if any proportion of migrants are already immune, but there are no reliable data on the proportion of vaccinated migrants and no expectation that people on the move will have their personal vaccination documentation on hand. With the increase in the migration of children younger than 5 years, there are increasing concerns about their vaccination history. This model represents many communities in Latin America and suggests that safe migration corridors can substantially contribute to the control of vaccine preventable diseases. FundingCoordination for the Improvement of Higher Education Personnel.

Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number.

BackgroundYellow fever is endemic in Africa and the Americas, occurring in urban or sylvatic environments. The infection presents varying symptoms, with high case-fatality among severe cases. In 2016, Brazil had sylvatic yellow fever outbreaks with more than 11 thousand cases, predominantly affecting the country’s Southeast region. The state of Minas Gerais accounted for 30% of cases, even after the vaccine had been included in the immunization calendar for at least 30 years.Methodology and principal findingsWe applied parameters described in the literature from yellow fever disease into a compartmental model of vector-borne diseases, using namely generation time intervals, vital host and vector parameters, and force of infection, using macroregions as the spatial unit and epidemiological weeks as the time interval. The model permits obtaining the reproduction number, which we analyzed from reported cases of yellow fever from 2016 to 2018 in residents of the state of Minas Gerais, Brazil. Minas Gerais recorded two outbreak periods, starting in EW 51/2016 and EW 51/2017. Of all the reported cases (3,304), 57% were men 30 to 59 years of age. Approximately 27% of cases (905) were confirmed, and 22% (202) of these individuals died. The estimated effective reproduction number varied from 2.7 (95% CI: 2.0–3.6) to 7.2 (95% CI: 4.4–10.9], found in the Oeste and Nordeste regions, respectively. Vaccination coverage in children under one year of age showed heterogeneity among the municipalities comprising the macroregions.ConclusionThe outbreaks in multiple parts of the state and the estimated Re values raise concern since the state population was partially vaccinated. Heterogeneity in vaccination coverage may have been associated with the occurrence of outbreaks in the first period, while the subsequent intense vaccination campaign may have determined lower Re values in the second period.

Wild-type Yellow fever virus in cerebrospinal fluid from fatal cases in Brazil, 2018.

Yellow fever virus (YFV) is the causative agent of yellow fever (YF), a hemorrhagic and viscerotropic acute disease. Severe YF has been described in approximately 15-25% of YF patients, with 20-50% of severe YF cases being fatal. Here we analyzed cerebrospinal fluid (CSF) samples collected during the YF outbreak in Brazil in 2018, aiming to investigate CNS neuroinvasion in fatal YFV cases. YFV RNA was screened by RT-qPCR targeting the 3'UTR region of the YFV genome in CSF. CSF samples were tested for the presence of anti-YFV IgM and neutralizing antibodies, coupled with routine laboratory examinations. Among the 13 patients studied, we detected anti-YFV IgM in CSF from eight patients and YFV RNA in CSF from five patients. YFV RNA genomic load in CSF samples ranged from 1.75×103 to 5.42×103 RNA copies/mL. We genotyped YFV from three CSF samples that grouped with other YFV samples from the 2018 outbreak in Brazil within the South-American I genotype. Even though descriptions of neurologic manifestations due to wild type YFV (WT-YFV) infection are rare, since the last YF outbreak in Brazil in 2017-2018, a few studies have demonstrated WT-YFV RNA in CSF samples from YF fatal cases. Serological tests indicated the presence of IgM and neutralizing antibodies against YFV in CSF samples from two patients. Although the presence of viral RNA, IgM and neutralizing antibodies in CSF samples could indicate neuroinvasiveness, further studies are needed to better elucidate the role of YFV neuroinvasion and possible impacts in disease pathogenesis.

Epidemiological description of and response to a large yellow fever outbreak in Edo state Nigeria, September 2018 - January 2019

BackgroundEdo State Surveillance Unit observed the emergence of a disease with “no clear-cut-diagnosis”, which affected peri-urban Local Government Areas (LGAs) from September 6 to November 1, 2018. On notification, the Nigeria Centre for Disease Control deployed a Rapid Response Team (RRT) to support outbreak investigation and response activities in the State. This study describes the epidemiology of and response to a large yellow fever (YF) outbreak in Edo State.MethodsA cross-sectional descriptive outbreak investigation of YF outbreak in Edo State. A suspected case of YF was defined as “Any person residing in Edo State with acute onset of fever and jaundice appearing within 14 days of onset of the first symptoms from September 2018 to January 2019”. Our response involved active case search in health facilities and communities, retrospective review of patients’ records, rapid risk assessment, entomological survey, rapid YF vaccination coverage assessment, blood sample collection, case management and risk communication. Descriptive data analysis using percentages, proportions, frequencies were made.ResultsA total of 209 suspected cases were line-listed. Sixty-seven (67) confirmed in 12 LGAs with 15 deaths [Case fatality rate (CFR 22.4%)]. Among confirmed cases, median age was 24.8, (range 64 (1-64) years; Fifty-one (76.1%) were males; and only 13 (19.4%) had a history of YF vaccination. Vaccination coverage survey involving 241 children revealed low YF vaccine uptake, with 44.6% providing routine immunisation cards for sighting. Risk of YF transmission was 71.4%. Presence of Aedes with high-larval indices (House Index ≥5% and/or Breteau Index ≥20) were established in all the seven locations visited. YF reactive mass vaccination campaign was implemented.ConclusionEdo State is one of the states in Nigeria with the highest burden of yellow fever. More males were affected among the confirmed. Major symptoms include fever, jaundice, weakness, and bleeding. Majority of surveillance performance indicators were above target. There is a high risk of transmission of the disease in the state. Low yellow fever vaccination coverage, and presence of yellow fever vectors (Ae.aegypti, Ae.albopictus and Ae.simpsoni) are responsible for cases in affected communities. Enhanced surveillance, improved laboratory sample management, reactive vaccination campaign, improved yellow fever case management and increased risk communication/awareness are very important mitigation strategies to be sustained in Edo state to prevent further spread and mortality from yellow fever.

Role of Th17 Cytokines in the Liver's Immune Response during Fatal Yellow Fever: Triggering Cell Damage Mechanisms.

Yellow fever (YF) is an infectious and acute viral haemorrhagic disease that triggers a cascade of host immune responses. We investigated the Th17 cytokine profile in the liver tissue of patients with fatal YF. Liver tissue samples were collected from 26 deceased patients, including 21 YF-positive and 5 flavivirus-negative patients, with preserved hepatic parenchyma architecture, who died of other causes. Histopathological and immunohistochemical analysis were performed on the liver samples to evaluate the Th17 profiles (ROR-γ, STAT3, IL-6, TGF-β, IL-17A, and IL-23). Substantial differences were found in the expression levels of these markers between the patients with fatal YF and controls. A predominant expression of Th17 cytokine markers was observed in the midzonal region of the YF cases, the most affected area in the liver acinus, compared with the controls. Histopathological changes in the hepatic parenchyma revealed cellular damage characterised mainly by the presence of inflammatory cell infiltrates, Councilman bodies (apoptotic cells), micro/macrovesicular steatosis, and lytic and coagulative necrosis. Hence, Th17 cytokines play a pivotal role in the immunopathogenesis of YF and contribute markedly to triggering cell damage in patients with fatal disease outcomes.

Yellow fever vaccination before and during the covid-19 pandemic in Brazil.

ABSTRACTOBJECTIVE To analyze the number of yellow fever vaccine doses administered before and during the covid-19 pandemic in Brazil.METHODS This is an ecological, time series study based on data from the National Immunization Program. Differences between the median number of yellow fever vaccine doses administered in Brazil and in its regions before (from April/2019 to March/2020) and after (from April/2020 to March/2021) the implementation of social distancing measures in the country were assessed via the Mann-Whitney test. Prais-Winsten regression models were used for time series analyses.RESULTS We found a reduction in the median number of yellow fever vaccine doses administered in Brazil and in its regions: North (-34.71%), Midwest (-21.72%), South (-63.50%), and Southeast (-34.42%) (p < 0.05). Series showed stationary behavior in Brazil and in its five regions during the covid-19 pandemic (p > 0.05). Brazilian states also showed stationary trends, except for two states which recorded an increasing trend in the number of administered yellow fever vaccine doses, namely: Alagoas State (before: β = 64, p = 0.081; after: β = 897, p = 0.039), which became a yellow fever vaccine recommendation zone, and Roraima State (before: β = 68, p = 0.724; after: β = 150, p = 0.000), which intensified yellow fever vaccinations due to a yellow fever case confirmation in a Venezuelan State in 2020.CONCLUSION The reduced number of yellow fever vaccine doses administered during the covid-19 pandemic in Brazil may favor the reemergence of urban yellow fever cases in the country.

Th22 cytokines and yellow fever: Possible implications for the immunopathogenesis of human liver infection

Yellow fever (YF) is an infectious disease considered a public health problem in tropical and subtropical areas. YF has many pathophysiological events that are correlated with the host immune response. In this study, the in situ Th22 cytokine profile was evaluated. Liver tissue samples were collected from 21 YFV-positive patients who died of the disease and five flavivirus-negative controls who died of other causes and whose hepatic parenchyma architecture was preserved. Immunohistochemical (IHC) analysis of tissues in the hepatic parenchyma of YF cases showed significantly higher expression of interleukin (IL)–22, IL-13, tumour necrosis factor-alpha, and FGF basic (FGF b) in YFV-positive cases than that in flavivirus-negative controls. These results indicate that the response of Th22 cytokines emerges as an alternative for a better understanding of adaptive immunity in the hepatic parenchyma, highlighting the role of cytokines in the repair and suppressive responses in the immunopathogenesis of YFV infection.

Malaria transmission in Africa: Its relationship with yellow fever and measles.

Malaria has been strongly linked to the transmission and pathophysiology of some viral diseases. Malaria and vaccine-preventable diseases often co-exist in endemic countries but the implication of their co-existence on their transmission dynamics and control is poorly understood. The study aims to evaluate the relationships between the incidence of malaria and cases of measles and yellow fever in Africa. The malaria incidence, death due to malaria, measles and yellow fever data were sourced from the WHO database. Poisson and zero-inflated time-trend regression were used to model the relationships between malaria and the two vaccine-preventable diseases. P-values <0.05 were considered statistically significant. A significant negative relationship existed between malaria incidence and measles cases (P<0.05), however, malaria showed a positive relationship with yellow fever (P<0.05). The relationships between death due to malaria and measles/yellow fever cases followed similar trends but with a higher level of statistical significance (P<0.001). Malaria varied negatively with measles cases but positively with yellow fever. The relationships observed in this study could be important for the management of malaria and the studied vaccine-preventable diseases. Increase vaccination coverage and/or malaria treatment could modulate the direction of these relationships.

Sustained circulation of yellow fever virus in Cameroon: an analysis of laboratory surveillance data, 2010\u20132020

BackgroundThe re-emergence of yellow fever poses a serious public health risk to unimmunized communities in the tropical regions of Africa and South America and unvaccinated travelers visiting these regions. This risk is further accentuated by the likely spread of the virus to areas with potential for yellow fever transmission such as in Asia, Europe, and North America. To mitigate this risk, surveillance of yellow fever is pivotal. We performed an analysis of laboratory-based surveillance of yellow fever suspected cases in Cameroon during 2010–2020 to characterize the epidemiology of yellow fever cases and define health districts at high risk.MethodWe reviewed IgM capture ELISA and plaque reduction neutralization test (PRNT) test results of all suspected yellow fever patients analyzed at Centre Pasteur of Cameroon, the national yellow fever testing laboratory, during 2010–2020.ResultsOf the 20,261 yellow fever suspected patient’s samples that were tested, yellow fever IgM antibodies were detected in 360 patients representing an annual average of 33 cases/year. A major increase in YF IgM positive cases was observed in 2015 and in 2016 followed by a decrease in cases to below pre-2015 levels. The majority of the 2015 cases occurred during the latter part of the year while those in 2016, occurred between February and May. This trend may be due to an increase in transmission that began in late 2015 and continued to early 2016 or due to two separate transmission events. In 2016, where the highest number of cases were detected, 60 health districts in the 10 regions of Cameroon were affected with the Littoral, Northwest and, Far North regions being the most affected. After 2016, the number of detected yellow fever IgM positive cases dropped.ConclusionOur study shows that yellow fever transmission continues to persist and seems to be occurring all over Cameroon with all 10 regions under surveillance reporting a case. Preventive measures such as mass vaccination campaigns and routine childhood immunizations are urgently needed to increase population immunity. The diagnostic limitations in our analysis highlight the need to strengthen laboratory capacity and improve case investigations.

Updating the Phylodynamics of Yellow Fever Virus 2016-2019 Brazilian Outbreak With New 2018 and 2019 São Paulo Genomes.

The recent outbreak of yellow fever (YF) in São Paulo during 2016–2019 has been one of the most severe in the last decades, spreading to areas with low vaccine coverage. The aim of this study was to assess the genetic diversity of the yellow fever virus (YFV) from São Paulo 2016–2019 outbreak, integrating the available genomic data with new genomes from patients from the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP). Using phylodynamics, we proposed the existence of new IE subclades, described their sequence signatures, and determined their locations and time of origin. Plasma or urine samples from acute severe YF cases (n = 56) with polymerase chain reaction (PCR) positive to YFV were submitted to viral genome amplification using 12 sets of primers. Thirty-nine amplified genomes were subsequently sequenced using next-generation sequencing (NGS). These 39 sequences, together with all the complete genomes publicly available, were aligned and used to determine nucleotide/amino acids substitutions and perform phylogenetic and phylodynamic analysis. All YFV genomes generated in this study belonged to the genotype South American I subgroup E. Twenty-one non-synonymous substitutions were identified among the new generated genomes. We analyzed two major clades of the genotypes IE, IE1, and IE2 and proposed the existence of subclades based on their sequence signatures. Also, we described the location and time of origin of these subclades. Overall, our findings provide an overview of YFV genomic characterization and phylodynamics of the 2016–2019 outbreak contributing to future virological and epidemiological studies.

Changing epidemiology of yellow fever virus in Oyo State, Nigeria

BackgroundYellow Fever is an acute viral hemorrhagic disease endemic in tropical Africa and Latin America and is transmitted through infected mosquitoes. The earliest outbreak of yellow fever in Nigeria was reported in Lagos in 1864 with subsequent regular outbreaks reported until 1996. A large epidemic of yellow fever occurred in Oyo State in April and May 1987 following an epidemic of sylvatic yellow fever in Eastern Nigeria the previous year. For 21 years, no further confirmed cases were reported until September 2017 following which Nigeria has been responding to successive outbreaks. The renewed onset of yellow fever outbreaks in Nigeria followed a global trend of reports and from other African countries. Yellow Fever disease has no cure, but control is through vaccination and vector control. Eliminating Yellow fever Epidemic (EYE) strategy to improve high-risk countries’ prevention, preparedness, detection, management, and response to yellow fever outbreaks was developed by the WHO in 2017 and launched in Nigeria in April 2018. Yet, poor vaccination coverage continues to be a cause for concern.Materials and methodsWe conducted a retrospective cross-sectional study that examines the resurgence of Yellow fever cases and outbreaks from 2013 to 2020 in Oyo State, Nigeria. The Yellow Fever data for both surveillance and routine Expanded Programme on Immunization (EPI) were the focus of the review. Surveillance data were retrieved from the State’s database reported by all 33 LGAs, maintained by the State and supported by the World Health Organization at the Zonal and State levels. The routine EPI data were retrieved from District Health Information Software (DHIS_2). The proportion of LGAs reporting at least one case of suspected yellow fever with a blood specimen and the number of suspected cases reported for each year within the period under review was measured. We also assessed the trend of confirmed cases and the incidence per 100,000 persons. Also, suspected cases of yellow fever were categorized into four age groups and their vaccination status was assessed. The State’s annual administrative routine vaccination coverage for yellow fever vaccine was compared with the number of confirmed cases for each year.ResultsThe proportion of LGAs reporting at least a case of suspected yellow fever, with blood samples collected, ranged from 6.1 to 84.9% between 2014 and 2020 while a total of 9 confirmed (8 cases) and probable (1 case) cases of yellow fever were recorded. However, there were no confirmed cases from the year 2013 to 2016, including 2018 but an upward trend of incidence of the disease per 100,000 persons from 0% to 2013 through 2018, to 3.5% in 2019, and then to 5.6% in 2020 was observed. 93 of 240 (39%) suspected yellow fever cases reported during the given period were observed to have received yellow fever vaccine.ConclusionsIn conclusion, the increase in the circulation of the yellow fever virus in the state reiterates the state is at a high risk of yellow fever transmission and underlines the need for viable interventions such as environmental hygiene to rid the environment of the disease vector’s ecological niche and improving routine EPI coverage to provide population immunity.

Aetiologies of acute undifferentiated febrile illness at the emergency ward of the University of Gondar Hospital, Ethiopia.

Causes of acute febrile illness (AFI) often remain undetermined in developing countries, due to overlap of symptoms and limited available diagnostics. We aimed to assess the aetiology of AFI in adults in a referral hospital in northwest Ethiopia. While all participants were tested for malaria by rapid diagnostic test (RDT), microscopy was only done on physician's request. Dengue virus (DENV) infections were detected using an RDT and ELISAs and dengue, yellow fever and chikungunya cases were identified by PCR. Bacterial aetiologies were investigated using blood culture and PCR. The aetiology of acute infection was identified for 20.5% of 200 patients enrolled. Eleven percent tested positive for Plasmodium, while microscopy was only requested for half of the identified malaria cases. For 4.0% of the Plasmodium-infected patients, an acute or past DENV (co-)infection was detected. We found 7.5% acute and 13.0% past DENV - all serotype 3 - infections. Bacterial infections were observed in 4.5% of the patients. Malaria is still a considerable aetiology of AFI and dengue is underrecognised. There are areas where both diseases occur concomitantly, and the DENV-3 serotype presumably spreads from Sudan to northern Ethiopia. As only 20.5% of the aetiologies were identified, a broader testing platform is required.

Endothelium Activation during Severe Yellow Fever Triggers an Intense Cytokine-Mediated Inflammatory Response in the Liver Parenchyma.

Yellow fever (YF) is a pansystemic disease caused by the yellow fever virus (YFV), the prototype species of the family Flaviviridae and genus Flavivirus, and has a highly complex host-pathogen relationship, in which endothelial dysfunction reflects viral disease tropism. In this study, the in situ endothelial response was evaluated. Liver tissue samples were collected from 21 YFV-positive patients who died due to the disease and five flavivirus-negative controls who died of other causes and whose hepatic parenchyma architecture was preserved. Immunohistochemical analysis of tissues in the hepatic parenchyma of YF cases showed significantly higher expression of E-selectin, P-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and very late antigen-4 in YFV-positive cases than in flavivirus-negative controls. These results indicate that endothelium activation aggravates the inflammatory response by inducing the expression of adhesion molecules that contribute to the rolling, recruitment, migration, and construction of the inflammatory process in the hepatic parenchyma in fatal YF cases.

Prevalence and evolution of clinical cases of Yellow Fever in Brazil between the years 2007 to 2016

Yellow Fever (YF) is a non-contagious infectious disease of variable symptoms that occurs mainly in tropical forests regions of the Americas and Africa and is caused by a Flavivirus belonging to the Flaviviridae family. Its vectors are mosquitoes of the genus Haemagogus, Sabethes and Aedes, and these have non-human primates as the main source of infection. In Brazil, there has been no record of urban AF since 1942, although the increase in cases of the wild form combined with low vaccination coverage contribute to the risk of re-urbanization of the disease Material and methods: For the study, epidemiological data were obtained from confirmed cases of Yellow Fever reported in the Notification System for Health Disorders (SINAN) available at the Informatics Department of the Unified Health System (DATASUS). Results and discussion: A total of 177 cases of were reported in Brazil, the year with the highest notification was in 2016 (52). The region with the highest occurrence of cases were the Southeast (95). Regarding the clinical evolution, of the 177 cases, 68 affected patients were cured, while 89 died from the reported injury, evidencing a high rate of lethality (50.2%). Conclusion: YF remains a public health problem, over the years there was a decrease in cases, this was due to immunization campaigns in the country, however, there was a significant increase in notifications in 2016, this whole panorama reinforces the need intensifying surveillance and expanding vaccine coverage.

Yellow fever outbreak in Ebonyi State, Nigeria, May-August 2019

An outbreak of yellow fever (YF) occurred in Ebonyi State, Nigeria in the year 2019 and a Rapid Response Team (RRT) from the Nigeria Centre for Disease Control, Abuja was deployed to investigate and characterize the outbreak and institute control measures. All suspected cases were identified, line-listed and analyzed. Between May and August 2019, 78 suspected YF cases were identified from 5 LGAs in Ebonyi State. Of these, 17 (21.8%) confirmed YF cases [including 4 deaths (case fatality rate (CFR): 23.5%)] were reported in 4 LGAs, with majority 13 (76.5%) from Izzi LGA. Age groups mostly affected were 0-9 years 5(29.4%) and 20-29 years 5(29.4%) with mean age 19 ±12 years. Majority were males 10 (58.8%). Overall, 50 eligible children participated in the YF VCS, 36(72.0%) had their vaccination cards available and only 24 (48.0%) of the cards had a record of YF vaccination. Aedes larva was found in 9(90.0%) of 10 households surveyed and adult species Aedes simpsoni complex emerged from the collections. The 2019 YF outbreak in Ebonyi state was as a result of an abundance of Aedes mosquitoes and low vaccination coverage. We recommend a Statewide YF risk assessment, mass YF vaccination campaign, vector control and enhanced YF surveillance is important to prevent future outbreaks and mortality.

Yellow Fever and Hepatitis B Co-Infection in A Nigerian Girl with Acute Febrile Jaundice: A Case Report

Yellow fever is a lethal re-emerging viral disease transmitted by infected Aedes mosquitoes. It is largely endemic in sub-Saharan Africa, with high risk of widespread outbreak in an unimmunized population. Recent outbreaks have been reported in several states in Nigeria. Yellow fever causes an acute febrile jaundice which can be confused with several endemic diseases, particularly viral hepatotropic infections such as hepatitis B, emphasizing the need for surveillance of co-viral pathogens during outbreaks. We report a rare case of yellow fever with hepatitis B co-infection in a 15-year-old girl who was successfully managed in a tertiary hospital in South-East Nigeria.