The prevalence of dengue virus serotypes in asymptomatic blood donors reveals the emergence of serotype 4 in Saudi Arabia

[Arbovirus - a threat to transfusion safety in Spain: a narrative review]

Arboviruses represent a threat to transfusion safety for several reasons: the presence of vectors and the notification of autochthonous cases in our region, the recent increase in the number of cases transmitted through blood and/or blood component transfusion, the high prevalence rates of RNA of the main arboviruses in asymptomatic blood donors, and their ability to survive processing and storage in the different blood components. In an epidemic outbreak caused by an arbovirus in our region, transfusion centres can apply different measures: reactive measures, related to donor selection or arbovirus screening, and proactive measures, such as pathogen inactivation methods. The study of the epidemiology of the main arboviruses and understanding the effectiveness of the different measures that we can adopt are essential to ensure that our blood components remain safe.

Dengue virus transmission risk in blood donation: Evidence from Thailand

Individuals infected with dengue virus (DENV) often show no symptoms, which raises the risk of DENV transfusion transmission (TT-DENV) in areas where the virus is prevalent. This study aimed to determine the evidence of DENV infection in blood donors from different geographic regions of Thailand. A cross-sectional study was conducted on blood donor samples collected from the Thai Red Cross National Blood Center and four regional blood centers between March and September 2020. Screening for DENV nonstructural protein 1 (NS1), anti-DENV immunoglobulin G (IgG), and IgM antibodies was performed on residual blood from 1053 donors using enzyme-linked immunosorbent assay kits. Positive NS1 and IgM samples indicating acute infection were verified using four different techniques, including quantitative real-time (q) RT-PCR, nested PCR, virus isolation in C6/36 cells, and mosquito amplification. DENV IgG seropositivity was identified in 89% (938/1053) of blood donors. Additionally, 0.4% (4/1053) and 2.1% (22/1053) of Thai blood donors tested positive for NS1 and IgM, respectively. The presence of asymptomatic dengue virus infection in healthy blood donors suggests a potential risk of transmission through blood transfusion, posing a concern for blood safety.

High prevalence of dengue, Zika, and chikungunya viruses in blood donors during a dengue outbreak and an endemic period in Colombia

Objective

Arboviruses pose a challenge in ensuring the supply of pathogen-free blood components because they are not routinely screened in blood banks, and blood components from infected asymptomatic donors could be transfused. This study aimed to detect and characterize arboviral infections in Colombian blood donors.

Methods

In a cross-sectional study, the prevalence of dengue (DENV), Zika (ZIKV), and chikungunya (CHIKV) viruses and co-infections of blood donors were compared between an epidemic period (November 2019-February 2020, n = 462) and an endemic period (November 2021-August 2022, n = 1,119). Viral RNA from each donor serum was purified, and the viruses were detected using a previously standardized multiplex hemi-nested RT-PCR protocol. Subsequently, donors who tested positive were surveyed 15 days after the detection of the virus to identify clinical characteristics related to the arboviral infection. The prevalences of each virus were presented as percentages and compared between epidemic and endemic periods.

Results

Significantly higher prevalences were found in the epidemic period compared with the endemic period for DENV (14.5 vs. 1.9%), ZIKV (7.8 vs. 0.3%), CHIKV (8 vs. 3.3%), and co-infections (4.3 vs. 0.2%). The survey response rate of positive donors in the two periods was 83/175 (47%). In total, 57% of the donors surveyed were asymptomatic. Symptomatic donors most frequently reported headache (31%), malaise (13%), arthralgia (10%), and fever/chills (8%).

Conclusion

The prevalence observed in epidemic and endemic periods was higher than that reported in other studies in the Americas. The high proportion of asymptomatic cases found, in addition to the mild and nonspecific manifestations among the symptomatic, may limit the effectiveness of the donor selection criteria used to mitigate the risk of transfusion-transmitted arboviruses.

Asymptomatic dengue infection rate: A systematic literature review

Objectives

Dengue infection is spreading worldwide. The clinical spectrum is broad and includes asymptomatic infections. This review provides an overview of the different proportions of asymptomatic infections described in epidemiological studies according to definitions, study designs, and detection methods.

Methods

Medline and Embase databases were searched without restriction of date or language. Studies were included if they reported data on the incidence or prevalence of asymptomatic dengue infections. The data were summarized and classified according to the definitions of the term 'asymptomatic'.

Results

A total of 74 studies were included. The mean proportion of asymptomatic infections among dengue-infected persons was 54% in 50 included studies. The prevalence of dengue infections detected in healthy persons was 0.2% in 24 included studies. The term 'asymptomatic' has been used to refer to 'clinically undetectable infection', but also to 'undiagnosed infection' or 'mild infection'. Only 8% were clinically undetectable laboratory-confirmed dengue infections.

Conclusion

The proportion of asymptomatic dengue infections varied greatly. Studies proving data on clinically undetectable laboratory-confirmed dengue infections were very few, but provided consistent results of low proportions of asymptomatic infections. These data challenge the assumption that the majority of dengue cases are asymptomatic.

The emergence of an imported variant of dengue virus serotype 2 in the Jazan region, southwestern Saudi Arabia

BACKGROUND

Dengue virus (DENV) infection is a global economic and public health concern, particularly in tropical and subtropical countries where it is endemic. Saudi Arabia has seen an increase in DENV infections, especially in the western and southwestern regions. This study aims to investigate the genetic variants of DENV-2 that were circulating during a serious outbreak in Jazan region in 2019.

METHODS

A total of 482 serum samples collected during 2019 from Jazan region were tested with reverse transcription-polymerase chain reaction (RT-PCR) to detect and classify DENV; positive samples underwent sequencing and bioinformatics analyses.

RESULTS

Out of 294 positive samples, type-specific RT-PCR identified 58.8% as DENV-2 but could not identify 41.2%. Based on sequencing and bioinformatics analyses, the samples tested PCR positive in the first round but PCR negative in the second round were found to be imported genetic variant of DENV-2. The identified DENV-2 imported variant showed similarities to DENV-2 sequences reported in Malaysia, Singapore, Korea and China. The results revealed the imported genetic variant of DENV-2 was circulating in Jazan region that was highly prevalent and it was likely a major factor in this outbreak.

CONCLUSIONS

The emergence of imported DENV variants is a serious challenge for the dengue fever surveillance and control programmes in endemic areas. Therefore, further investigations and continuous surveillance of existing and new viral strains in the region are warranted.

Transfusion-transmitted arboviruses: Update and systematic review

BACKGROUND

The detection of the first cases of transfusion-transmitted West Nile virus in 2002 posed a new challenge for transfusion safety. Institutions like the World Health Organization have stated that blood transfusion centers need to know the epidemiology of the different emerging infectious agents and their impact on blood transfusion. The aim of the study is to review the published cases of arbovirus transmission through transfusion of blood or blood components and to analyze their main clinical and epidemiological characteristics.

MATERIAL AND METHODS

Systematic literature searches were conducted in MEDLINE, Embase and Scopus. Pairs of review authors selected a variety of scientific publications reporting cases of transfusion-transmitted arboviruses. Main clinical and epidemiological characteristics were reviewed of the cases described. The study protocol was registered in PROSPERO CRD42021270355.

RESULTS

A total of 74 cases of transfusion-transmitted infections were identified from 10 arboviruses: West Nile virus (n = 42), dengue virus (n = 18), Zika virus (n = 3), yellow fever vaccine virus (n = 3), tick-borne encephalitis virus (n = 2), Japanese encephalitis virus (n = 2), Powassan virus (n = 1), St. Louis encephalitis virus (n = 1), Ross River virus (n = 1) and Colorado tick fever virus (n = 1). The blood component most commonly involved was red blood cells (N = 35, 47.3%; 95% confidence interval [CI] 35.9% to 58.7%). In 54.1% (N = 40; 95% CI: 42.7%-65.47%) of the cases, the recipient was immunosuppressed. Transmission resulted in death in 18.9% (N = 14; 95% CI: 10.0%-27.8%) of the recipients. In addition, 18 additional arboviruses were identified with a potential threat to transfusion safety.

DISCUSSION

In the last 20 years, the number of published cases of transfusion-transmitted arboviruses increased notably, implicating new arboviruses. In addition, a significant number of arboviruses that may pose a threat to transfusion safety were detected. In the coming years, it is expected that transmission of arboviruses will continue to expand globally. It is therefore essential that all responsible agencies prepare for this potential threat to transfusion safety.

Prevalence of Chikungunya, Dengue and Zika viruses in blood donors: a systematic literature review and meta-analysis

BACKGROUND

Blood transfusion centres should understand the epidemiology of emerging diseases that are transmissible through the transfusion of blood components. The risk of transmission of arboviruses through this route has become apparent in recent years. The aim of our study is to summarise the reported prevalence (viraemic rate, seroprevalence and/or antigen detection) of Chikungunya (CHIKV), Dengue (DENV) and Zika (ZIKV) viruses in blood donors according to screening test used and world region.

MATERIALS AND METHODS

We conducted a systematic literature review and meta-analysis having searched for information in the main bibliographic databases (MEDLINE, Embase, and Scopus). The prevalence for each of the viruses was calculated according to the screening test used and geographic location.

RESULTS

We included 18 records on CHIKV, 71 on DENV, and 27 on ZIKV. The highest prevalences of RNA for CHIKV were 1.9% in Puerto Rico (2014), 1.0% in Thailand (2009), and 1.0% in French Polynesia (2014-15). The highest prevalences of RNA for DENV were 5.5% in Saudi Arabia (2015-16), 2.3% in Madeira, Portugal (2012-13), and 0.6% in Brazil (2012). The highest prevalences of RNA for ZIKV were 2.8% in French Polynesia (2013-14), 2.7% in Brazil (2015-16), and 1.8% in Martinique (2016). Overall seroprevalence, as assessed by IgG antibodies, was 21.6% for CHIKV, 24.0% for DENV, and 5.1% for ZIKV.

DISCUSSION

Our study shows a high proportion of donors who are viraemic and asymptomatic, especially during outbreaks, with prevalences surpassing 5% for DENV, 1% for CHIKV, and 2% for ZIKV. These data confirm a clear threat to blood transfusion safety. The elevated seroprevalence for these three arboviruses is also indicative of their wide circulation in populations, correlating with an increased risk of infected but asymptomatic donors. Health centres and institutions must address this threat, especially in tropical regions where the biggest outbreaks occur.

Serological Evidence of West Nile Virus Infection Among Humans, Horses, and Pigeons in Saudi Arabia

Purpose

This study was designed to investigate the seroprevalence of WNV antibodies in humans, horses, and pigeons in the Eastern Province of Saudi Arabia.

Materials and Methods

Blood samples were collected from 323 humans, 147 horses, and 282 pigeons from two regions, Al-Ahsa and Al-Qatif, in East of Saudi Arabia. Serum samples were tested for anti-WNV antibodies by ELISA.

Results

The percentage of anti-WNV antibodies in the human population was found to be 9.6% (3.1% in females and 6.5% in males). This percentage was much higher in horses, as 71.4% (105/147) of the horses had anti-WNV antibodies. However, no statistically significant difference in the anti-WNV antibody prevalence was found among horses from the two regions, Al-Ahsa (73.9%) and Al-Qatif (70.3%) (P value 0.665, 95% CI 0.37–1.82). No significant difference was found in the frequency of WNV antibodies among different age groups from humans or horses. Noticeably, 72.7% of the horses had detectable anti-WNV antibodies by the age of 1 year. In total, 53.19% (150/282) of the pigeons in the study had anti-WNV antibodies.

Conclusion

Our study provided the first evidence for anti-WNV antibody detection in humans and pigeons. This study further ascertained the high seroprevalence of the virus in horses as reported previously by Hemida et al 2019. Overall data indicates that WNV is endemic in Saudi Arabia. These findings suggest that more attention should be given to the diagnosis and reporting of WNV infections in human and animals and monitoring of virus circulation in the environment.

High seroprevalence of anti-DENV IgM in blood donors in an early outbreak in the Federal District of Brazil, 2019

Dengue is endemic in Brazil, and several Brazilian cities are affected by frequent seasonal outbreaks of the disease. During the outbreaks the possibility of transfusion-transmitted dengue (TTD) is increased, mainly by the presence of asymptomatic or oligosymptomatic infections in eligible blood donors. The retrospective assessment of anti-DENV IgM and NS1 seroprevalence during a given time interval may indicate the need for measures for the previous screening of DENV infection in blood donors. In this context, we performed retrospective screening for anti-DENV IgM and NS1 in blood donors from the Federal District of Brazil during the early outbreak that occurred in 2019, the largest outbreak in recent years. In total, 450 blood donations were screened for anti-DENV IgM and DENV NS1 using commercial enzyme-linked immunosorbent assay kits (Panbio Dengue IgM Capture ELISA and Platelia Dengue NS1 Ag, respectively). Among the tested plasma samples, 16 % (72/450) presented anti-DENV IgM; no samples presented DENV NS1. Despite the apparent absence of antigenaemia in tested blood donations, the high prevalence of anti-DENV IgM highlights the importance of DENV screening in blood donors, principally during outbreak periods.

Dengue virus detection in Lao PDR and Colombia: Comparative evaluation of PCR tests

OBJECTIVES

Dengue virus (DENV) detection by polymerase chain reaction (PCR) facilitates diagnosis of dengue fever, which is the most frequent arboviral disease globally. Two studies were performed in countries with high dengue incidence, to assess the diagnostic performance of different PCR techniques.

METHODS/RESULTS

Two hundred and seventy-nine acute phase blood samples from febrile patients were analyzed for DENV by the RealStar Dengue RT-PCR kit (Altona Diagnostics) as gold standard in comparison with the Tropical Fever Core multiplex PCR (Fast Track Diagnostics). In total, 102 samples collected in Savannakhet Province (Lao PDR, Southeast Asia) in 2013 and 35 samples from Valledupar (Colombia, South America) tested positive for DENV by RealStar RT-PCR. In comparison, the Tropical Fever Core multiplex PCR detected 65.0% (65/102) and 68.6% (24/35) of these samples as positive for DENV in Savannakhet and Valledupar, respectively. Diagnostic sensitivity of the multiplex PCR strongly correlated with viral load. A subset of DENV PCR-confirmed samples was additionally tested by BNITM in house Dengue Type RT-PCR in comparison with two commercial test kits (RealStar Dengue Type RT-PCR [Altona Diagnostics], Dengue differentiation PCR [Fast Track Diagnostics]). The leading dengue serotype in Savannakhet was DENV-3 (58% [29/50]), while DENV-1 (53.8% [14/26]) was the predominant serotype found in samples collected in Valledupar by BNITM-type PCR. However, three DENV serotypes were circulating in Valledupar and in Savannakhet. In 2015, additional studies found predominantly DENV-4 (71% [12/17]) in Savannakhet.

CONCLUSIONS

Both studies emphasized that routine diagnostics in both regions will benefit from an expanded use of highly sensitive pan-dengue PCRs.

Lack of Zika Virus and Other Recognized Flaviviruses among the Mosquito Vectors during and Post the Hajj Mass Gathering

Makkah city, Kingdom of Saudi Arabia (KSA), contains many of the world’s mosquito vectors of parasitic and arboviral disease and is the site of the Hajj mass gathering. As such there is a risk of exportation and globalization of vector-borne viruses, including the re-emerging Zika virus (ZIKV). There was international concern regarding the introduction of ZIKV to KSA and potential international spread of the virus following the 2016 Hajj which took place few days after the Rio summer Olympics at the height of the ZIKV pandemic. We aimed to detect flaviviruses, including ZIKV, circulating among mosquito hosts in the city of Makkah during and post the 2016 Hajj pilgrimage. Mosquitos (adults and larvae) were sampled from 15 sites in Makkah city during and post the 2016 Hajj and identified to species by morphological keys. Mosquitos were pooled according to date of collection, location, and species. A Pan-Flaviviruses RT-PCR assay that enables identification of 51 flaviviruses species and three tentative species was used to detect flavivirus RNA directly from mosquito homogenates. Between the 10 September and 6 October 2016, 9412 female mosquitos were collected. Of these, 81.3% were Aedes aegypti, 18.6% were Culex species, and 0.1% were Anopheles species. Of the total 493 mosquito pools generated, 242 (49%) were positive by the Pan-Flaviviruses primer set. Sequence analysis revealed that none of the mosquitos carried a pathogenic flavivirus, including ZIKV, but were infected with a novel insect-specific flavivirus. We found no pathogenic flaviviruses circulating in Makkah city during and post the 2016 Hajj and no evidence of introduction of ZIKV through the pilgrimage. Enhanced vector-borne diseases surveillance, prevention, and control are crucial in KSA especially during international mass gatherings such as the annual Hajj to prevent outbreaks and the spread of viruses with epidemic and pandemic potentials.

Detection of DENV-2 and Insect-Specific Flaviviruses in Mosquitoes Collected From Jeddah, Saudi Arabia

Background

Mosquito-borne diseases are rapidly spreading due to increasing international travel and trade. Routine mosquito surveillance and screening for mosquito-borne pathogens can be early indicators for local disease transmission and outbreaks. However, arbovirus detection in mosquito vectors has rarely been reported in Saudi Arabia.

Methods

A total of 769,541 Aedes and Culex mosquitoes were collected by Black Hole traps during routine mosquito surveillance in the first half of 2016. Culex. quinquefasciatus and Ae. aegypti were the most prevalent species observed. Twenty-five and 24 randomly selected pools of Ae. aegypti and Cx. quinquefasciatus, respectively, were screened for arboviruses by RT-PCR.

Results

Dengue 2 (DENV-2) and four strains of insect-specific flaviviruses, including one of cell-fusing agent virus (CFAV) and three of Phlebotomus-associated flavivirus (PAFV) were detected in pools of Ae. aegypti. We also detected 10 strains of Culex flavivirus (CxFV) in pools of Cx. quinquefasciatus. Phylogenetic analysis using whole genome sequences placed the DENV strain into the cosmopolitan 1 sub-DENV-2 genotype, and the CxFVs into the African/Caribbean/Latin American genotype. These analyses also showed that the DENV-2 strain detected in the present study was closely related to strains detected in China in 2014 and in Japan in 2018, which suggests frequent movement of DENV-2 strains among these countries. Furthermore, the phylogenetic analysis suggested at least five introductions of DENV-2 into Saudi Arabia from 2014 through 2018, most probably from India.

Conclusions

To our knowledge, this study reports the first detection of four arboviruses DENV, CFAV, PAFV, and CxFV in mosquitoes in Saudi Arabia, which shows that they are co-circulating in Jeddah. Our findings show a need for widespread mosquito-based arbovirus surveillance programs in Saudi Arabia, which will improve our understanding of the transmission dynamics of the mosquito-borne arboviruses within the country and help early predict and mitigate the risk of human infections and outbreaks.

Utility of a multiplex real-time polymerase chain reaction for combined detection and serotyping of dengue virus in paediatric patients hospitalised with severe dengue: A report from Chennai

Objective

Molecular detection and serotyping are rapid, sensitive and accurate techniques for early diagnosis of paediatric dengue. The present study evaluates multiplex real-time polymerase chain reaction (PCR) for diagnosis of dengue virus in children hospitalised with severe dengue (SD) and attempts to establish an association of clinical severity with specific serotypes.

Methods

Four hundred and eighty-five samples were received from hospitalised paediatric patients with suspected dengue from March 2019 to February 2020. Multiplex real time PCR was employed for diagnosis. An in-house real-time PCR that combined diagnosis and serotyping was established. Non-structural protein 1 (NS1) assay and real-time PCR were assessed for their accuracy in diagnosing severe paediatric dengue.

Results

Three hundred and twenty-five (67%) patients were positive for dengue RNA by real-time PCR. All four serotypes were identified throughout the year; dengue serotype 2 (DEN-2) was predominant (61%) followed by DEN-3, 20%. Compared to the commonly used NS1 testing, multiplex real-time PCR showed greater sensitivity in diagnosing SD.

Conclusions

Compared to NS1, multiplex real-time PCR is a rapid and accurate diagnostic test for children hospitalised with SD. DEN-2 was the predominant serotype in severe cases. Continued surveillance of serotypes should be carried out year-round in endemic areas.

First report on seroprevalence and risk factors of dengue virus in Jordan

Background

There are no data available on dengue epidemiology in Jordan. This is the first study of the seroprevalence and risk factors of dengue virus (DENV) infection in Jordan.

Methods

Sera samples from 892 apparently healthy individuals from all over Jordan were tested for DENV by enzyme-linked immunosorbent assay and a validated questionnaire was completed by all participants to identify and rank possible risk factors.

Results

The seroprevalence was 24.6% (95% confidence interval 21.8 to 27.5). In univariate regression analysis, age, education, history of travel, living in rainy areas and practicing agriculture were significantly (p<0.05) associated with seropositivity. The multivariate logistic regression model showed that those who live in a rainy climate (odd ratio [OR] 1.7), are older (OR 2.3), have a history of international travel (OR 1.5) and are male with a history of international travel had a significantly greater odds of DENV seropositivity (OR 3.4).

Conclusions

These data suggest that DENV circulates in Jordan and that cases may be imported or locally transmitted. Further research is needed to determine the circulating DENV serotypes and vectors in Jordan. Given the high rate of DENV seropositivity, dengue should be considered as a differential diagnosis in febrile diseases in Jordan, especially among populations living in rainy climates.

Dengue fever in Saudi Arabia: A review of environmental and population factors impacting emergence and spread

Dengue fever (DF) is the most important mosquito-transmitted viral disease causing a large economic and disease burden in many parts of the world. Most DF research focuses on Latin America and Asia, where burdens are highest. There is a critical need for studies in other regions where DF is an important public health problem but less well-characterized and can differ, such as the Middle East. The first documented case of DF in Saudi Arabia occurred in 1993. After a decade of sporadic outbreaks, the disease was declared endemic in 2004 and this designation persists. Climate, sociodemographic factors, and increasing urbanization impact the spread of DF in Saudi Arabia, as in other areas. However, DF transmission in Saudi Arabia is also affected by several unique factors, including large numbers of migrant workers and religious pilgrims from other dengue endemic areas across the Middle East, North Africa, and Asia. Important knowledge gaps relate to the role of climatic factors as drivers of DF in Saudi Arabia and the role of foreign workers and pilgrims in the original and continuous importation of dengue virus. Filling these gaps would improve health system preparedness.

Dengue seroprevalence among asymptomatic blood donors during an epidemic outbreak in Central-West Brazil

Dengue virus (DENV) transmission by blood transfusion is an important route of viral acquisition during outbreaks. The prevalence of DENV markers (viral RNA, NS1, anti-DENV IgM, and IgG) among blood donors in Central-West Brazil has never been evaluated. Our aim was to evaluate the full set of serological and molecular markers for DENV among blood donors of the Federal District of Brazil during an extensive outbreak in 2016. We found an anti-DENV IgM prevalence of 6.74% (n = 32/475). Of 475, 20 samples (4.21%) were also anti-DENV IgG positive. All samples were non-reactive for NS1 and DENV RNA. Our results imply that a significant proportion of the tested donors had experienced asymptomatic infection. More studies are necessary to evaluate the real prevalence of DENV viremia in blood donors from the Federal District of Brazil and if specific measures are needed to routinely test the blood donors for DENV RNA during outbreaks.

Low frequency of asymptomatic dengue virus-infected donors in blood donor centers during the largest dengue outbreak in Taiwan

To determine the prevalence of asymptomatic dengue virus-infected blood donors during the largest dengue outbreak in Taiwan history occurred in 2015, we examined the evidence of dengue virus (DENV) infection by the detection of DENV RNA genome using real-time reverse transcription-polymerase chain reaction (real-time RT-PCR), DENV NS1 antigen using rapid diagnosis test (RDT) and anti-dengue antibody using IgM/IgG capture enzyme-linked immunosorbent assay (capture ELISA) and RDT in eight thousand serum samples from blood donations to the blood centers of the Taiwan Blood Services Foundation (TBSF) in Kaohsiung City and Tainan City during the largest dengue outbreak in Taiwan history occurred in 2015. Only one serum sample was positive for DENV RNA detection by using dengue-specific real-time RT-PCR, the virus was DENV-2 determined by serotype-specific real-time RT-PCR and sequencing, and the DENVs in the serum were confirmed as being infectious by a plaque assay. The recipient of this blood did not develop any dengue fever symptom on follow-up. None of the samples was NS1 RDT-reactive. Seventeen IgM-positive samples were identified. There was a low prevalence of asymptomatic confirmed or probable DENV-infected blood donors in our study (0.013% and 0.21%, respectively), and no symptomatic transfusion-transmitted dengue (TT dengue) was developed during the largest dengue outbreak in Taiwan history in highly endemic areas and periods.

Diversity of dengue virus-3 genotype III in Jeddah, Saudi Arabia

BACKGROUND

Dengue is the most important arboviral disease in tropical and subtropical countries. Dispersal of the vector and an increase in migratory flow between countries have led to large epidemics and severe clinical outcomes. Over the past 20 years, dengue epidemics have become more wide-spread and frequent. Previous studies have shown that dengue is endemic in Jeddah, Makkah and Al-Madinah in western Saudi Arabia as well as in Jazan region in the southern part of the country. The four serotypes of dengue virus (DENV) have been reported from western Saudi Arabia. It has been suggested that pilgrims could play a significant and unique role in DENV-1 and DENV-2 introduction into Saudi Arabia, especially in the cities of Jeddah, Makkah and Al-Madinah during Hajj and Umrah seasons. However, only limited data on DENV-3 in Saudi Arabia are available.

METHODS

All available DENV-3 sequences published and unpublished from Saudi Arabia and other countries were retrieved from Genbank and gene sequence repository and phylogenetically analyzed to examine the diversity of DENV-3 into the city of Jeddah.

RESULTS

Based on the analysis of the envelope gene and non-structural 1 (E/NS1) junction sequences, we show that there were at least four independent introductions of DENV-3, all from genotype III into Jeddah. The first introduction was most probably before 1997 as Saudi virus isolates from 1997 formed a cluster without any close relationship to other globally circulating isolates, suggesting their local circulation from previous introduction events. Two introductions were most probably in 2004 with isolates closely-related to isolates from Africa and India (Asia), in addition to another introduction in 2014 with isolates clustering with those from Singapore (Asia).

CONCLUSIONS

Our data shows that only genotype III isolates of DENV-3 are circulating in Jeddah and highlights the potential role of pilgrims in DENV-3 importation into western Saudi Arabia and subsequent exportation to their home countries during Hajj and Umrah seasons. Therefore, it is highly recommended to establish DENV sentinel surveillance programs targeting clinical cases and the mosquito vector in the country to implement effective control measures and to minimize the burden of the disease in the kingdom.

Dengue infection in patients with febrile illness and its relationship to climate factors: A case study in the city of Jeddah, Saudi Arabia, for the period 2010-2014

Dengue is an important global arboviral disease with expanding geographical range. It is a major public health concern in Western Saudi Arabia since its first detection in the city of Jeddah in 1994. In this retrospective study, we examined dengue incidence among febrile patients suspected for acute dengue infection at King Abdulaziz University Hospital, Jeddah from 2010 to 2014 and we tried to determine the effect of climate factors on dengue incidence in the city. Acute dengue incidence rates among clinically suspected patients showed annual variation with a range from 29.3% to 57%. Male gender and 11-30 years age range were found to be risk factors for dengue infection in Jeddah. While dengue infections can be detected throughout the year, most cases occurred between March and July with peaks in May and June. Seasonality of dengue was found to be significantly associated with the decrease in relative humidity and increase in temperature within the range of ∼25 °C to ∼33 °C but not extremely hot temperatures. Moreover, we found that rainfall during winter (November to February) has a significant lag effect on dengue infection among febrile patients in the city. Jeddah is the second largest city in Saudi Arabia and a major hub for pilgrims because of its close proximity to the holy sites in the Kingdom. The observed high rates of acute dengue infections clearly show the endemicity of dengue in Jeddah. The observed higher incidence rates at young age are expected to cause an increase in severe dengue cases in the future especially that multiple dengue serotypes are co-circulating in the city. Furthermore, the significant association between the different climate factors and dengue and their impact on the disease seasonality should help in the effort to implement effective control and management measures to reduce dengue burden in the Kingdom.

Transmission of dengue virus from deceased donors to solid organ transplant recipients: case report and literature review

Dengue fever is a vector-transmitted viral infection. Non-vectorial forms of transmission can occur through organ transplantation. We reviewed medical records of donors and recipients with suspected dengue in the first post-transplant week. We used serologic and molecular analysis to confirm the infection. Herein, we describe four cases of dengue virus transmission through solid organ transplantation. The recipients had positive serology and RT-PCR. Infection in donors was detected through serology. All cases presented with fever within the first week after transplantation. There were no fatal cases. After these cases, we implemented dengue screening with NS1 antigen detection in donors during dengue outbreaks, and no new cases were detected. In the literature review, additional cases had been published through August 2017. Transmission of Dengue virus can occur through organ donation. In endemic regions, it is important to suspect and screen for dengue in febrile and thrombocytopenic recipients in the postoperative period.

Dengue Hemorrhagic Fever Virus in Saudi Arabia: A Review

Dengue fever is a global disease with a spectrum of clinical manifestation ranging from mild febrile disease to a severe disease in the form of dengue hemorrhagic fever and dengue shock syndrome. Dengue virus is one viral hemorrhagic fever that exists in the Kingdom of Saudi Arabia in addition to Alkhurma (Alkhurma) Hemorrhagic Fever, Chikungunya virus, Crimean-Congo Hemorrhagic Fever, and Rift Valley Fever. The disease is limited to the Western and South-western regions of Saudi Arabia, where Aedes aegypti exists. The majority of the cases in Saudi Arabia had mild disease and is related to serotypes 1-3 but not 4. The prospect for Dengue virus control relies on vector control, health education, and possibly vaccine use. Despite extensive collaborative efforts between multiple governmental sectors, including Ministry of Health, Ministry of Municipalities and Rural Affairs, and Ministry of Water, dengue remains a major public health concern in the regions affected.

First complete genome sequence of circulating dengue virus serotype 3 in Jeddah, Saudi Arabia

Here we report the first full-length genome sequence of dengue virus serotype 3 (DENV-3) from a strain isolated from a patient in Jeddah, Saudi Arabia, in 2014. The genome consists of 10 635 bp and shows close similarity to circulating genotype III isolates from Singapore, suggesting possible importation, most probably during religious pilgrimages to Saudi Arabia.