High prevalence of West Nile virus in equines from the two provinces of Pakistan

Lessons Learned from West Nile Virus Infection:Vaccinations in Equines and Their Implications for One Health Approaches

Humans and equines are two dead-end hosts of the mosquito-borne West Nile virus (WNV) with similar susceptibility and pathogenesis. Since the introduction of WNV vaccines into equine populations of the United States of America (USA) in late 2002, there have been only sporadic cases of WNV infection in equines. These cases are generally attributed to unvaccinated and under-vaccinated equines. In contrast, due to the lack of a human WNV vaccine, WNV cases in humans have remained steadily high. An average of 115 deaths have been reported per year in the USA since the first reported case in 1999. Therefore, the characterization of protective immune responses to WNV and the identification of immune correlates of protection in vaccinated equines will provide new fundamental information about the successful development and evaluation of WNV vaccines in humans. This review discusses the comparative epidemiology, transmission, susceptibility to infection and disease, clinical manifestation and pathogenesis, and immune responses of WNV in humans and equines. Furthermore, prophylactic and therapeutic strategies that are currently available and under development are described. In addition, the successful vaccination of equines against WNV and the potential lessons for human vaccine development are discussed.

From mosquitoes to menace: Unveiling the dangers of West Nile virus in Pakistan

Pakistan, a subtropical nation, has seen a rapid rise in Arboviral transmission in the past decade. Environmental hazards such as intense monsoon rains and yearly floods in addition to unsanitary living conditions pose an increased risk of arboviral infections. In recent years, the emergence and spread of West Nile virus (WNV), which can lead to a life-threatening meningoencephalitis, in Pakistan has alarmed the health care authorities of an impending outbreak. Health professionals and policymakers should give paramount importance to prevent its transmission across Pakistan as another arboviral outbreak would wreak havoc on the already fragile health infrastructure of the country. Proactive surveillance and prompt reporting are crucial for mitigating this threat as there are no vaccines available to prevent WNV infection.

West Nile, Sindbis and Usutu Viruses: Evidence of Circulation in Mosquitoes and Horses in Tunisia

Mosquito-borne diseases have a significant impact on humans and animals and this impact is exacerbated by environmental changes. However, in Tunisia, surveillance of the West Nile virus (WNV) is based solely on the surveillance of human neuroinvasive infections and no study has reported mosquito-borne viruses (MBVs), nor has there been any thorough serological investigation of anti-MBV antibodies in horses. This study therefore sought to investigate the presence of MBVs in Tunisia. Among tested mosquito pools, infections by WNV, Usutu virus (USUV), and Sindbis virus (SINV) were identified in Cx. perexiguus. The serosurvey showed that 146 of 369 surveyed horses were positive for flavivirus antibodies using the cELISA test. The microsphere immunoassay (MIA) showed that 74 of 104 flavivirus cELISA-positive horses were positive for WNV, 8 were positive for USUV, 7 were positive for undetermined flaviviruses, and 2 were positive for tick-borne encephalitis virus (TBEV). Virus neutralization tests and MIA results correlated well. This study is the first to report the detection of WNV, USUV and SINV in Cx. perexiguus in Tunisia. Besides, it has shown that there is a significant circulation of WNV and USUV among horses, which is likely to cause future sporadic outbreaks. An integrated arbovirus surveillance system that includes entomological surveillance as an early alert system is of major epidemiological importance.

Comparison of Serological Methods for Tick-Borne Encephalitis Virus-Specific Antibody Detection in Wild Boar and Sheep: Impact of the Screening Approach on the Estimated Seroprevalence

Tick-borne encephalitis virus (TBEV) is a flavivirus transmitted by ticks. Serological screenings in animals are performed to estimate the prevalence and distribution of TBEV. Most screenings consist of a primary screening by ELISA, followed by confirmation of positive samples by plaque reduction neutralization tests (PRNTs). In this study, 406 wild boar sera were tested with 2 regularly used commercial ELISAs for flavivirus screening in animals (Immunozym FSME (TBEV) IgG All Species (Progen) and ID Screen West Nile Competition (Innovative Diagnostics)) and PRNTs for TBEV and USUTU virus. The results showed that the Immunozym and IDScreen ELISAs had low relative sensitivities of 23% and 20%, respectively, compared to the PRNT results. The relative specificities were 88% and 84% due to cross reactions with USUTU virus-specific antibodies. The minimal TBEV prevalence in our sample set was 8.6% when determined by PRNT. When the screening approach of ELISA testing followed by PRNT confirmation was applied, a TBEV seroprevalence of only 2.0% and 1.7% was found. The suboptimal performance of the ELISAs was confirmed by testing sera collected from experimentally TBEV-infected sheep. While the PRNT detected TBEV specific antibodies in 94% of samples collected between 7 and 18 days post-infection, the ELISAs classified only 50% and 31% of the samples as positive. Both routinely used ELISAs for TBEV antibody screening in animal sera were shown to have a low sensitivity, potentially leading to an underestimation of the true prevalence, and furthermore cross-react with other flavivirus antibodies.

West Nile virus outbreak in Pakistan: Another potential public health threat in the pipeline?

West Nile virus (WNV), a single-stranded RNA virus belonging to the family of Flaviviridae, is an arbovirus transmitted to humans predominantly by mosquito bites. It exhibits a wide range of clinical findings ranging from asymptomatic presentation to severe several neurological disorders. WNV has afflicted several countries around the globe including Pakistan. News of yet another outbreak in the country by WNV is circulating again. Concerned authorities should act vigilantly before the endemic takes over completely and bring down the already bereaving healthcare of Pakistan.

Epidemiological trends of mosquito-borne viral diseases in Pakistan

Globally, arboviruses are public health problems. Pakistan has seen a fast-paced increase in mosquito-borne Flavivirus diseases such as dengue because of deforestation, climate change, urbanization, poor sanitation and natural disasters. The magnitude and distribution of these diseases are poorly understood due to the lack of a competitive nationwide surveillance system. In dengue-endemic countries, the recent epidemics of chikungunya (CHIKV) and human West Nile virus (WNV) have created panic among the public and are thought to provoke an outbreak of Zika virus (ZIKV) in Pakistan. Recently, hospital-based surveillance has indicated the presence of Japanese encephalitis virus (JEV), which is deeply concerned by developing countries such as Pakistan. The situation could become more devastating because of poorly developed diagnostic infrastructure. To date, no licensed vaccine has been used in Pakistan, and preventive measures are mainly based on vector control. This review provides comprehensive information concerning the association of risk factors with disease occurrence, epidemiological trends, and prediction of the spread of mosquito-borne diseases, attention to new threats of ZIKV, and future perspectives by benchmarking global health policies.

West Nile Virus and Tick-Borne Encephalitis Virus Are Endemic in Equids in Eastern Austria

The emergence of West Nile virus (WNV) and Usutu virus (USUV) in addition to the autochthonous tick-borne encephalitis virus (TBEV) in Europe causes rising concern for public and animal health. The first equine case of West Nile neuroinvasive disease in Austria was diagnosed in 2016. As a consequence, a cross-sectional seroprevalence study was conducted in 2017, including 348 equids from eastern Austria. Serum samples reactive by ELISA for either flavivirus immunoglobulin G or M were further analyzed with the plaque reduction neutralization test (PRNT-80) to identify the specific etiologic agent. Neutralizing antibody prevalences excluding vaccinated equids were found to be 5.3% for WNV, 15.5% for TBEV, 0% for USUV, and 1.2% for WNV from autochthonous origin. Additionally, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to detect WNV nucleic acid in horse sera and was found to be negative in all cases. Risk factor analysis did not identify any factors significantly associated with seropositivity.

Phylogenetic analysis of West Nile virus: first report of lineage 1 in donkey in Turkey

West Nile virus (WNV), a member of the Flaviviridae, is a major arbovirus that causes West Nile fever. Previous data showed the prevalence of the WNV serologically and molecular in Turkey, and the presence of lineage 1 in horses and humans has been reported. This is the first notification of partial phylogeny of WNV detected in donkeys in the northeast of Turkey (on the Iranian border). Blood serum samples collected from 25 donkeys without clinical symptoms were tested by RT-PCR. Sequence analysis of the sample detected as positive was performed. Multiple sequence alignments of reference sequences taken from GenBank were performed using the ClustalW method using the MEGA6 program. Partial nucleotide sequences of the capsid gene coding region revealed that the strains are closely related to viruses of lineage 1, clade 1a. According to the phylogenetic tree, the TUR/Igdir/donkey strain was included in the same cluster as the strain (KJ958922) previously obtained from horses in Turkey and the strain (GQ851658) from the Central African Republic. This study is the first report to show the circulation of WNV lineage 1 in donkeys in Turkey.

Diversity, distribution and relative abundance of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan

The present study was conducted to evaluate the diversity, distribution (C) and relative abundance (RA) of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan. Collection of specimens (n = 1087) was made during September 2018 to July 2019 at six different habitats including freshwater bodies, rice fields, animal sheds, indoors, drains and sewage waters. Specimens were collected through light traps, pyrethrum spray, aspirators and nets and subsequently killed, preserved and then arranged in entomological boxes for identification. Three genera were identified namely Culex, Anopheles and Aedes. A total of fourteen species were identified namely: Cx. quinquefasciatus (Say, 1823), An. stephensi (Liston, 1901), Cx. tritaeniorhynchus (Giles, 1901), Ae. vittatus (Bigot, 1861), An. maculatus (Theobald, 1901), An. fluviatilis (James, 1902), Cx. vishnui (Theobald, 1901), Ae. aegypti (Linnaeus, 1762) An. subpictus (Grassi, 1899), An. dthali (Patton, 1905), An. culicifascies (Giles, 1901), An. pallidus (Theobald, 1901), Ae. albopictus (Skuse, 1894) and An. annularis (van der Wulp, 1884). Cx. quinquefasciatus was found constantly distributed in the study area with RA = 16.5% and C = 100%. An. annularis was found as a satellite species, sporadically distributed in the study area having RA = 0.9% and C = 17%. Diversity indices of mosquitoes in the studied habitats were found as, Shannon-Wiener Index (2.415), Simpson Index (9.919), Fisher's Index (2.269) and Margalef's Index (1.859). A statistically significant difference was recorded in mosquito diversity in the six habitats (Kruskal-Wallis, chi-squared, H = 17.5, df = 5, P = 0.003 at α = 0.05). The present study encompasses mosquito fauna of Malakand, Pakistan with respect to diversity, relative abundance and distribution in diverse habitats and all seasons of the year. This will assist scientists working in various fields related with epidemiology, medical and veterinary entomology, ecology and allied areas of biological sciences.

Viral Diseases that Affect Donkeys and Mules

Simple Summary

Donkeys have been neglected and threatened by abandonment, indiscriminate slaughter, and a lack of proper sanitary management. They are often treated as “small horses.” However, donkeys and horses have significant genetic, physiological, and behavioral differences. Specific knowledge about viral infectious diseases that affect donkeys and mules is important to mitigate disease outbreaks. Thus, the purpose of this review is to provide a brief update on viral diseases of donkeys and mules and ways to prevent their spread.

Abstract

Donkeys (Equus asinus) and mules represent approximately 50% of the entire domestic equine herd in the world and play an essential role in the lives of thousands of people, primarily in developing countries. Despite their importance, donkeys are currently a neglected and threatened species due to abandonment, indiscriminate slaughter, and a lack of proper sanitary management. Specific knowledge about infectious viral diseases that affect this group of Equidae is still limited. In many cases, donkeys and mules are treated like horses, with the physiological differences between these species usually not taken into account. Most infectious diseases that affect the Equidae family are exclusive to the family, and they have a tremendous economic impact on the equine industry. However, some viruses may cross the species barrier and affect humans, representing an imminent risk to public health. Nevertheless, even with such importance, most studies are conducted on horses (Equus caballus), and there is little comparative information on infection in donkeys and mules. Therefore, the objective of this article is to provide a brief update on viruses that affect donkeys and mules, thereby compromising their performance and well-being. These diseases may put them at risk of extinction in some parts of the world due to neglect and the precarious conditions they live in and may ultimately endanger other species’ health and humans.

Serological Evidence of West Nile Virus in Wild Birds in Bangladesh

West Nile Virus (WNV) is a vector-borne zoonotic disease maintained in a sylvatic cycle involving mosquito vectors and birds. To detect WNV and other flavivirus infections in wild resident and migratory birds, we tested 184 samples from 19 identified species within nine families collected during 2012–2016 from four districts in Bangladesh. We tested serum samples for the immunoglobulin G (IgG) antibody against WNV using competitive Enzyme-Linked Immunosorbent Assay (c-ELISA), whereas tracheal and cloacal swabs were subjected to consensus Polymerase Chain Reaction (c-PCR) for the detection of the flavivirus RNA. Overall, we detected 11.9% (n = 22; 95% CI: 0.07–0.16) samples were seropositive, including 15.9% in the migratory wild birds and 10.7% in the resident wild birds. The migratory wild Tufted duck showed 28.5% seropositivity, whereas the resident wild house crows showed 12.5% seropositivity. None of the swab samples was positive for flavivirus RNA infection (0%, n = 184; 95% CI: 0–0.019). These study findings recommend continued surveillance for early detection and to better understand the epidemiology of WNV and other flavivirus circulation in both birds and mosquitoes in Bangladesh.

Serosurvey of West Nile virus in horses and detection of West Nile virus antigen in mosquitoes in Kaduna State, Nigeria

West Nile virus (WNV) causes a mosquito-borne zoonotic disease of public health importance. The aim of this study was to determine the state of WNV infection in horses and detect the virus antigen in mosquitoes trapped in stables in Kaduna State Nigeria. The study was carried out in Kaduna State, Nigeria, and 368 horses were screened for the presence of antibodies against WNV using an IgG competitive enzyme-linked immunosorbent assay. Of the 368 samples tested, 331 (89.9%) were positive for WNV antibodies. Mosquitoes from the stables were tested for WNV antigen using a VectorTest kit, and of the 31 pools of adult mosquitoes tested, only 5 (16.1%) pools tested positive for WNV antigen. This finding showed that WNV infection has occurred in horses and that there is evidence of circulation of the virus by mosquitoes in Kaduna State, Nigeria.

Identification of a protective epitope in Japanese encephalitis virus NS1 protein

Japanese encephalitis virus (JEV) is one of the most important culex transmitted-flaviviruses, which can cause encephalitis in humans. Although non-structural protein 1 (NS1) of JEV does not stimulate neutralizing antibodies, this protein can provide high immunoprotection in vivo. The protective epitopes and the protective mechanism of NS1 still remain unclear. In this study, we generated five different monoclonal antibodies (mAbs) targeting the NS1 protein of JEV. In vitro experiments revealed that none of these five antibodies neutralized the JEV infection. In mouse protection studies, one of these mAbs, designated 2B8, provided a therapeutic effect against JEV lethal challenge (70% survival rate). Using peptide mapping analysis, we found that mAb 2B8 reacted with the epitope ²²⁵PETHTLWGD²³³ in the NS1 protein, in which any mutations among amino acid residues T²²⁸, H²²⁹, L²³¹ or W²³² could cause binding failure of 2B8 to the NS1 protein. Furthermore, mice immunized with KLH-polypeptide (²²⁵PETHTLWGD²³³) showed reduced mortality following JEV challenge. Collectively, we found a new protective epitope in the JEV NS1 protein. These results may facilitate the development of therapeutic agent and subunit-based vaccines based on the NS1 protein.

Equine viral encephalitis: prevalence, impact, and management strategies

Members of several different virus families cause equine viral encephalitis, the majority of which are arthropod-borne viruses (arboviruses) with zoonotic potential. The clinical signs caused are rarely pathognomonic; therefore, a clinical diagnosis is usually presumptive according to the geographical region. However, recent decades have seen expansion of the geographical range and emergence in new regions of numerous viral diseases. In this context, this review presents an overview of the prevalence and distribution of the main viral causes of equine encephalitis and discusses their impact and potential approaches to limit their spread.

Epidemiology of West Nile Virus in the Eastern Mediterranean region: A systematic review

Background

West Nile Virus (WNV), a member of the genus Flavivirus, is one of the most widely distributed arboviruses in the world. Despite some evidence for circulation of WNV in countries summarized by the World Health Organization as the Eastern Mediterrian Regional Office (EMRO), comprehensive knowledge about its epidemiology remains largely unknown. This study aims to provide a concise review of the published literature on WNV infections in the Eastern Mediterranean Regional Office of WHO (EMRO).

Methodology/principal findings

A systematic review of WNV prevalence studies on humans, animals and vectors in the EMRO region was performed by searching: Web of Science, Science Direct, Scopus, PubMed, Embase and Google Scholar. Finally, 77 citations were included, comprising 35 seroprevalence studies on general population (24460 individuals), 15 prevalence studies among patients (3439 individuals), 22 seroprevalence studies among animals (10309 animals), and 9 studies on vectors (184242 vector species). Of the 22 countries in this region, five had no data on WNV infection among different populations. These countries include Kuwait, Bahrain, Oman, Syria and Somalia. On the other hand, among countries with available data, WNV-specific antibodies were detected in the general population of all investigated countries including Djibouti (0.3–60%), Egypt (1–61%), Iran (0–30%), Iraq (11.6–15.1%), Jordan (8%), Lebanon (0.5–1%), Libya (2.3%), Morocco (0–18.8%), Pakistan (0.6–65.0%), Sudan (2.2–47%), and Tunisia (4.3–31.1%). WNV RNA were also detected in patient populations of Iran (1.2%), Pakistan (33.3%), and Tunisia (5.3% –15.9%). WNV-specific antibodies were also detected in a wide range of animal species. The highest seropositivity rate was observed among equids (100% in Morocco) and dogs (96% in Morocco). The highest seroprevalence among birds was seen in Tunisia (23%). In addition, WNV infection was detected in mosquitoes (Culex, and Aedes) and ticks (Argas reflexus hermanni). The primary vector of WNV (Culex pipiens s.l.) was detected in Djibouti, Egypt, Iran and Tunisia, and in mosquitoes of all these countries, WNV was demonstrated.

Conclusions

This first systematic regional assessment of WNV prevalence provides evidence to support the circulation of WNV in the EMRO region as nearly all studies showed evidence of WNV infection in human as well as animal/vector populations. These findings highlight the need for continued prevention and control strategies and the collection of epidemiologic data for WNV epidemic status, especially in countries that lack reliable surveillance systems.

West Nile Virus (WNV) is a mosquito-borne Flavivirus belonging to the Flaviviridae family, which is endemic in a vast geographical area, including the EMRO region. However, the epidemiology of WNV in the EMRO region remains poorly understood. To address this gap, we performed a systematic review on WNV prevalence studies conducted on human populations, animals and vectors across Eastern Mediterranean countries. Our review indicated the infection of most investigated human, animal and vector populations with WNV; however, the paucity of epidemiological data underline the need for integrated surveillance programs as well as continued deployment of prevention and control strategies.

Widespread circulation of West Nile virus, but not Zika virus in southern Iran

West Nile virus (WNV) and Zika virus (ZIKV) are mosquito-borne viral infections. Over the past few decades, WNV has been associated with several outbreaks involving high numbers of neuroinvasive diseases among humans. The recent re-emergence of ZIKV has been associated with congenital malformation and also with Guillain-Barre syndrome in adults. The geographic range of arthropod-borne viruses has been rapidly increasing in recent years. The objectives of this study were to determine the presence of IgG specific antibodies and the genome of WNV and ZIKV in human samples, as well as WNV and ZIKV genomes in wild-caught mosquitoes in urban and rural areas of the Hormozgan province, in southern Iran. A total of 494 serum samples were tested for the presence of WNV and ZIKV IgG antibodies using ELISA assays. One hundred and two (20.6%) samples were reactive for WNV IgG antibodies. All serum samples were negative for ZIKV IgG antibodies. Using the multivariable logistic analysis, age (45+ vs. 1-25; OR = 3.4, 95% C.I.: 1.8-6.3), occupation (mostly outdoor vs. mostly indoor; OR = 2.4, 95% C.I.: 1.1-5.2), and skin type(type I/II vs. type III/IV and type V/VI; OR = 4.3, 95% C.I.: 1.7-10.8 and OR = 2.7, 95% C.I.: 1.3-5.5 respectively, skin types based on Fitzpatrick scale) showed significant association with WNV seroreactivity. We collected 2,015 mosquitoes in 136 pools belonging to 5 genera and 14 species. Three pools of Culex pipiens complex were positive for WNV RNA using real-time reverse transcription polymerase chain reaction (rtRT-PCR). ZIKV RNA was not detected in any of the pools. All WNV ELISA reactive serum samples were negative for WNV RNA. In conclusion, we provided evidence of the establishment of WNV in southern Iran and no proof of ZIKV in serum samples or in mosquito vectors. The establishment of an organized arbovirus surveillance system and active case finding strategies seems to be necessary.

Dengue Outbreak in Peshawar: Clinical Features and Laboratory Markers of Dengue Virus Infection

BACKGROUND

Dengue is a tropical disease caused by dengue virus (DENV). It is one of the most significant arthropod-borne viral infection.

OBJECTIVES

The aim of the current study was to characterize epidemiological, clinical features and laboratory markers of dengue infection during the recent epidemic in Peshawar, KP.

METHODS

During the prospective hospital-based observational study, 2000 dengue suspected cases were serologically examined at Lady Reading Hospital (LRH) Peshawar. Dengue NS1 antigen and Dengue IgG and IgM antibody ELISA tests were conducted for the confirmation of dengue infection. Data regarding the clinical features, platelet count and liver function tests were also recorded for the dengue positive patients.

RESULTS

Out of total samples 415 (21%) cases including 309 (74%) male and 106 (25%) female were detected positive for the dengue infection. In the dengue positive patients, the highest prevalence was observed in the age group of 21-40years with 160 (38%) followed by the age group of 1-20years with 89 (21%) patients. Fever was recorded in 100% of the dengue patients followed by a headache and fatigue in 73% and liver abnormality observed in 70% of the cases. During laboratory examinations IgM antibody was detected in 180 cases, followed by IgG antibody in 87, NS1 antigen in 43, NS1 antigen along with IgG and IgM antibodies in 41 dengue positive cases. Another combine detection of NS1 antigen with IgM antibody, NS1 antigen with IgG antibody and both IgG and IgM antibodies was observed in 21, 21, 22 dengue cases respectively.

CONCLUSION

It was concluded that the dengue infection can be early diagnosed on the basis of described clinical features and with the detection of dengue-specific NS1 antigen along with antibodies such as IgG and IgM.

Human West Nile Virus Disease Outbreak in Pakistan, 2015-2016

Like most of the world, Pakistan has seen an increase in mosquito-transmitted diseases in recent years. The magnitude and distribution of these diseases are poorly understood as Pakistan does not have a nation-wide system for reporting disease. A cross-sectional study to determine which flaviviruses were causing of arboviral disease in Pakistan was instituted. West Nile virus (WNV) is a cause of seasonal fever with neurotropic findings in countries that share borders with Pakistan. Here, we describe the active and persistent circulation of WNV in humans in the southern region of Pakistan. This is the first report of WNV causing neurological disease in human patients in this country. Of 997 enrolled patients presenting with clinical features suggestive of arboviral disease, 105 were positive for WNV IgM antibodies, and 71 of these patients possessed WNV-specific neutralizing antibodies. Cross-reactivity of WNV IgM antibodies with Japanese encephalitis virus (JEV) occurred in 75 of these 105 patients. WNV co-infections with Dengue viruses were not a contributing factor for the severity of disease. Nor did prior exposure to dengue virus contribute to incidence of neurological involvement in WNV-infected patients. Patients with WNV infections were more likely to present with altered mental status, seizures, and reduced Glasgow Coma scores when compared with JEV-infected patients. Human WNV cases and vector numbers exhibited a temporal correlation with climate.

Detection of selected arboviral infections in patients with history of persistent fever in Pakistan

Surveillance is a valuable tool for understanding prevailing and previously undiagnosed infections in a geographic area. We examined 480 archived serum samples from patients with history of persistent fever (>40°C, 60-72h) who were referred to hospitals in Rawalpindi/Islamabad, Lahore, and Faisalabad districts for dengue antibody detection in 2014-15. Each sample was processed for detection of antigens and seroconversion, using real-time polymerase chain reaction and enzyme linked immunosorbent assay, respectively, against dengue haemorrhagic fever (DHF) virus serotypes 1-4, West Nile virus fever (WNVF), Crimean-Congo haemorrhagic fever (CCHF), and Chikungunya virus (CGV). The presence of antigens and antibodies to at least one of the studied viral haemorrhagic fevers (VHFs) was detected in 465 (96.8%, 95% CI: 94.9-98.1) and 442 samples (92.1%, 95% CI: 89.3-94.2), respectively. No sera were found positive to CCHF. There was a significant association between gender and positivity to at least one of the VHFs (χ²=8.12, df=1, p<0.005). Except for DHF serotype 2 and 3 (ττ=0.41), Goodman and Kruskal's Tau statistic revealed no significant association for occurrence of different viruses within the studied population (ττ=0-0.06). Cosinor analysis confirmed significant seasonality, with a higher number of cases of persistent fever in August through November, peaking in October. The study suggests circulation of multiple arthropod-borne viral infections and, in addition to DHF, ascertain the needs for screening patients for CGV and WNVF too. It also demonstrates the necessity of well-integrated disease surveillance in several geographic regions and at-risk populations in Pakistan to develop appropriate disease and vector control strategies.

Flaviviruses as a Cause of Undifferentiated Fever in Sindh Province, Pakistan: A Preliminary Report

Arboviral diseases are expanding worldwide, yet global surveillance is often limited due to diplomatic and cultural barriers between nations. With human encroachment into new habitats, mosquito-borne viruses are also invading new areas. The actual prevalence of expanding arboviruses is unknown in Pakistan due to inappropriate diagnosis and poor testing for arboviral diseases. The primary objective of this study was to document evidence of flavivirus infections as the cause of undifferentiated fever in Pakistan. Through a cooperative effort between the USA and Pakistan, patient exposure to dengue virus (DENV), West Nile virus (WNV), and Japanese encephalitis virus (JEV) was examined in Sindh Province for the first time in decades. Initial results from the 2015 arbovirus season consisting of a cross-sectional study of 467 patients in 5 sites, DENV NS1 antigen was identified in 63 of the screened subjects, WNV IgM antibodies in 16 patients, and JEV IgM antibodies in 32 patients. In addition, a number of practical findings were made including (1) in silico optimization of RT-PCR primers for flavivirus strains circulating in the Middle East, (2) shipping and storage of RT-PCR master mix and other reagents at ambient temperature, (3) Smart phone applications for the collection of data in areas with limited infrastructure, and (4) fast and reliable shipping for transport of reagents and specimens to and from the Middle East. Furthermore, this work is producing a group of highly trained local scientists and medical professionals disseminating modern scientific methods and more accurate diagnostic procedures to the community.

A High-Performance Multiplex Immunoassay for Serodiagnosis of Flavivirus-Associated Neurological Diseases in Horses

West Nile virus (WNV), Japanese encephalitis virus (JEV), and tick-borne encephalitis virus (TBEV) are flaviviruses responsible for severe neuroinvasive infections in humans and horses. The confirmation of flavivirus infections is mostly based on rapid serological tests such as enzyme-linked immunosorbent assays (ELISAs). These tests suffer from poor specificity, mainly due to antigenic cross-reactivity among flavivirus members. Robust diagnosis therefore needs to be validated through virus neutralisation tests (VNTs) which are time-consuming and require BSL3 facilities. The flavivirus envelope (E) glycoprotein ectodomain is composed of three domains (D) named DI, DII, and DIII, with EDIII containing virus-specific epitopes. In order to improve the serological differentiation of flavivirus infections, the recombinant soluble ectodomain of WNV E (WNV.sE) and EDIIIs (rEDIIIs) of WNV, JEV, and TBEV were synthesised using the Drosophila S2 expression system. Purified antigens were covalently bonded to fluorescent beads. The microspheres coupled to WNV.sE or rEDIIIs were assayed with about 300 equine immune sera from natural and experimental flavivirus infections and 172 nonimmune equine sera as negative controls. rEDIII-coupled microspheres captured specific antibodies against WNV, TBEV, or JEV in positive horse sera. This innovative multiplex immunoassay is a powerful alternative to ELISAs and VNTs for veterinary diagnosis of flavivirus-related diseases.