Seroepidemiological Investigations Research Articles

Development of a blocking ELISA for detection of Japanese encephalitis virus antibodies in pig and horse sera

Japanese encephalitis virus (JEV) is a mosquito-borne virus that can infect pigs, horses, and other mammals, including humans. Sero-epidemiological investigations of JEV have been performed using hemagglutination inhibition (HI), virus neutralization (VN) tests and enzyme-linked immunosorbent assay (ELISA). A need exists for a new ELISA that can detect JEV antibodies in the sera of several animal species. We aimed to develop a blocking ELISA (B-ELISA) for detecting JEV antibodies in pig and horse serum samples. JEV antibodies in 218 pig and 315 horse serum samples were measured using HI and VN tests. The purified KV1899-306 strain was used as an antigen for B-ELISA. The purified antibody (7A13) was conjugated with horseradish peroxidase and used as a detector antibody. The sera of pigs and horses to measure antibody against JEV were subjected to B-ELISA and analyzed. The B-ELISA had a diagnostic sensitivity of 94.6% to 100%, a specificity of 91.2 to 100%, and an accuracy of 94.9 to 98.6% compared with those of the HI and VN tests in pig and horse sera. The B-ELISA had a higher correlation with pig sera (r = 0.89 and 0.90 for VN and HI) than with horse sera (r = 0.75 and to 0.79). The new B-ELISA could be useful in the sero-surveillance of JEV in pig and horse sera and replace indirect ELISA.

COVID-19 Seropositivity Among Adults of Tribal Origin Attending a Primary Care Centre in Wayanad Kerala- A Cross Sectional Study

Introduction: Coronavirus Disease-2019 (COVID-19) is a highly contagious viral illness caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Serological surveys help in understanding the burden of past infections. The World Health Organisation (WHO) suggests the need for populationbased sero-epidemiological investigations to acquire data for implementing containment measures. The tribal population, being the most marginalised and vulnerable section, is at a higher risk for COVID-19. However, there is limited literature regarding the seroprevalence of COVID-19 among the tribal population in our country. Aim: To assess the COVID-19 seropositivity, associated factors, and knowledge among adults of tribal origin attending a primary care centre in Wayanad, Kerala. Materials and Methods: A cross-sectional study was conducted among 279 adults of tribal origin, aged between 18 and 95 years, attending a primary tribal healthcare centre at Amrita Institute of Medical Sciences, Kochi, Kerala, India, from August 2021 to October 2021. A semistructured questionnaire was used to collect socio-demographic details, history of COVID-19 infection, vaccination status, and participants’ knowledge and awareness about COVID-19. Antibody presence was tested using the WANTAI test kit. Data analysis was performed using Statistical Package for Social Sciences(SPSS) version 21.0 A multivariable logistic regression was conducted following univariate analysis to identify independent factors associated with COVID-19 seropositivity. Results: The mean age of the study population was 45.34±15.86 years. Among the 279 participants, the proportion of seropositivity to COVID-19 antibodies was found to be 245 (87.8%) with a 95% confidence interval (CI) of 83.98 to 91.62. Regarding knowledge and awareness related to COVID-19, 186 (66.7%) participants were not aware of the common symptoms of COVID19. Individuals aged above 60 years had a five times higher probability of having COVID-19 antibodies compared to those aged 30 years or younger (adjusted odds ratio (aOR) 4.71, 95% CI 0.111 to 20.025). Those who had received atleast one dose of the vaccine were nine times more likely to have seropositivity (aOR 8.58, 95% CI 1.390 to 53.028). Conclusion: The seropositivity of COVID-19 was high at 87.8%. Older people and vaccinated individuals were more likely to be seropositive. Therefore, it is necessary to strengthen vaccination efforts among all age groups. Continued sero-surveillance and vaccination surveys need to be conducted to gain more insights into the antibody kinetics of this novel pathogen.

The burden of the coronavirus disease 2019 virus infection in Burkina Faso: Results from a World Health Organization UNITY population-based, age-stratified sero-epidemiological investigation.

This study aimed to estimate the anti-SARS-CoV-2 antibody seroprevalence in the general population of Bobo-Dioulasso and Ouagadougou (Burkina Faso). We collected from March to April 2021 blood samples from randomly selected residents in both main cities based on the World Health Organization (WHO) sero-epidemiological investigations protocols and tested them with WANTAI SARS-CoV-2 total antibodies enzyme-linked immunosorbent assay (ELISA) kits intended for qualitative assessment. We also recorded participants' socio-demographic and clinical characteristics and information on exposure to SARS-CoV-2. Data were analysed with descriptive and comparative statistics. We tested 5240 blood samples collected between 03 March and 16 April 2021. The overall test-adjusted seroprevalence for SARS-CoV-2 antibodies was (67.8% [95% CI 65.9-70.2]) (N = 3553/3982). Seroprevalence was highest among participants aged 15-18 years old (74.2% [95% CI 70.5-77.5]) (N = 465/627), compared with those aged 10-14 years old (62.6% [95% CI 58.7-66.4]) (N = 395/631), or those over 18 (67.6% [95% CI 66.2-69.1]) (N = 2693/3982). Approximately 71.0% (601/860) of participants aged 10-18 years old who tested positive for SARS-CoV-2 antibodies experienced no clinical COVID-19 symptoms in the weeks before the survey, compared with 39.3% (1059/2693) among those aged over 18 years old. This study reports the results of the first known large serological survey in the general population of Burkina Faso. It shows high circulation of SARS-CoV-2 in the two cities and a high proportion of asymptomatic adolescents. Further studies are needed to identify the SARS-CoV-2 variants and to elucidate the factors protecting some infected individuals from developing clinical COVID-19.

Learning from serosurveillance for SARS-CoV-2 to inform pandemic preparedness and response

Learning from serosurveillance for SARS-CoV-2 to inform pandemic preparedness and response

Seroprotection against tetanus in southern Vietnam.

Ongoing tetanus cases and sporadic outbreaks of vaccine-preventable diseases associated with routine vaccination programmes remain problems in many low and middle-income countries, including Vietnam. With no human-to-human transmission or natural immunity, tetanus antibody levels indicate both individual risk of tetanus and gaps in vaccination programmes. To investigate gaps in immunity to tetanus in Vietnam, a country with a historically high level of tetanus vaccination coverage, tetanus antibodies were measure by ELISA from samples selected from a long-term serum bank, established for the purposes of general-population seroepidemiological investigations in southern Vietnam. Samples were selected from 10 provinces, focussing on age-groups targeted by national vaccination programmes for infants and pregnant women (Expanded Programme on Immunization, EPI, and Maternal and Neonatal Tetanus, MNT). Antibodies were measured from a total of 3864 samples. Highest tetanus antibody concentrations occurred in children under 4years old, over 90% of whom had protective levels. Approximately 70% of children aged 7-12years had protective antibody concentrations although there was variation among provinces. For infants and children, there were no significant differences in tetanus protection between males and females, but for adults aged 20-35years, in five of the ten provinces surveyed, protection against tetanus was higher in females (p<0.05) who are eligible for booster doses under the MNT programme. In seven of ten provinces, antibody concentrations were inversely related to age (p<0.01) and protection of older individuals was generally low. Widespread immunity to tetanus toxoid is seen in infants and young children consistent with the high coverage rates reported for diptheria tetanus toxoid and pertussis (DTP) in Vietnam. However, the lower antibody concentrations seen in older children and men suggest reduced immunity to tetanus in populations not targeted by EPI and MNT programmes.

Improved diagnostic sensitivity of human strongyloidiasis using point-of-care mixed recombinant antigen-based immunochromatography

Strongyloidiasis is a neglected tropical disease that can cause fatal complications due to hyperinfection and disseminated strongyloidiasis in immunocompromised patients. We used two Strongyloides stercoralis recombinant antigenic proteins, L3NieAg.01 (NIE) and IgG-immunoreactive antigen (SsIR), to develop the recombinant antigen-based immunochromatography test (ICT) kit. We constructed and compared kits using either the NIE (NIE ICT kit) or the SsIR (SsIR ICT kit) antigens and a kit using a mixture of both (NIE-SsIR ICT kit) for detection of anti-Strongyloides IgG antibody in human serum samples. Serum samples from normal healthy individuals (Group I, n = 40), proven strongyloidiasis patients (Group II, n = 100), and those with other parasitic infections (Group III, n = 154) were evaluated. Sensitivity and specificity were 81.0% and 84.0% for the NIE ICT kit, 89.0% and 83.5% for the SsIR ICT kit, and 95.0% and 90.2% for the NIE-SsIR ICT kit, respectively. The NIE-SsIR ICT kit provided the best diagnostic results; it can supplement stool examination for clinical diagnosis and can be used to screen for asymptomatic S. stercoralis infection in people at risk in endemic areas. The NIE-SsIR ICT kit can also be used in large-scale sero-epidemiological investigations in endemic areas without the need for additional facilities or ancillary supplies.

Validation of dried blood spots samples for the screening of hepatitis B virus surface by enzyme immunoassay method

Dried Blood Spots (DBS) are blood collection carriers that facilitate the storage and transport of samples. Used for quality control during sero-epidemiological investigations, DBS eluate are not the conventional specimen indicated by manufacturers for enzyme immunoassay method (EIA) for hepatitis B virus surface (HBs antigen).The aim of our study was to evaluate DBS eluates used as a matrix for EIA of HBs antigen in a reference laboratory.This study took place from August 2016 to November 2017 at the Centre for Diagnosis and Research on AIDS and other infectious diseases (CeDReS) in Abidjan, Côte d'Ivoire. We used a panel of 149 whole blood samples from blood donors. The DBS performed with these samples were analyzed after elution with the HBsAg (version ULTRA) ELISA, Dia.Pro Diagnostic Bioprobes S.R.L., Sesto San Giovanni, Italy. The technical performance (sensitivity and specificity and kappa coefficient) of the test performed on DBS was determined for different ratios (optical density/threshold value) compared to the results obtained on the plasma used as reference.We obtained a sensitivity of 100% with DBS for all ratios.The specificity increased according to the ratio of optical density of the individual EIA reaction to the threshold value, with 6.09%, 47.0%, and 83.0%, respectively, for ratios of 1.0, 3.0, and 5.0. Best performance was observed at ratio of 10.0 with a sensitivity and specificity of 100%.In conclusion, DBS eluate can be used for the diagnosis of viral hepatitis B and would be useful for conducting sero-epidemiological investigations. However, ratio giving best performance must be determined for each enzyme immunoassay method kits.

A Cross-Sectional Seroepidemiological Study on Infectious Bursal Disease in Backyard Chickens in the Mymensingh District of Bangladesh.

Infectious bursal disease (IBD) is a highly contagious disease that causes significant economic loss in chickens. A cross-sectional study was conducted in the Mymensingh district of Bangladesh to determine the seroprevalence of IBD virus (IBDV) antibodies in backyard chickens and their association with different epidemiological risk factors. A total of 460 serum samples were randomly collected from backyard chickens that had not been previously vaccinated against IBDV. The collected sera were examined using an enzyme-linked immunosorbent assay (ELISA). Data on epidemiological risk factors were collected through face-to-face interviews with owners and subjected to both uni- and multivariable risk analyses to determine their association with IBDV infection. Using ELISA, the overall seroprevalence of IBDV antibodies in backyard chickens was 83.4% (95% confidence interval: 79.8%–86.6%), among which, a significantly higher seroprevalence was recorded in females (83.4%, 345/350), 4–6 weeks age group (95.3%, 244/256), and unhealthy (95.0%, 57/60) backyard chickens than those of males, other age groups, and healthy chickens, respectively. Furthermore, chickens reared in free-ranging housing systems (93.3%, 280/300) and poor-conditioned houses (98.0%, 147/150) showed a significantly higher seropositivity of IBDV antibodies than those reared in separated housing systems and other hygienic-conditioned houses, respectively. Moreover, compared with their counterparts, a higher but nonsignificant seroprevalence of IBDV antibodies was observed in backyard chickens that were selected from Fulbaria Upazila (88.8%; 80/90) and which were brought from the marketplace (85.7%, 60/70). A higher seropositivity of IBDV antibodies was shown to be statistically associated with various critical epidemiological risk factors, indicating that field strains of IBDV were exposed in backyard chickens and could be readily transferred horizontally. Proper prevention and control methods, villagers' awareness of IBD, and the rapid and widespread use of seroepidemiological investigations could help to reduce the spread of IBDV infection in backyard chickens.

Study protocol for the SeMaCo study: A longitudinal regional cohort study to assess COVID-19 seroprevalence in blood donors

Introduction: Serologic studies are crucial for clarifying the regional dynamics of the SARS-CoV-2 coronavirus pandemic as well as the success of a vaccination campaign against COVID-19. We describe a cohort study investigating the seroprevalence of antibodies against SARS-CoV-2 in Magdeburg (Saxony-Anhalt, Germany). Protocol and study design: The SeMaCo study (Serologische Untersuchungen bei Blutspendern des Großraums Magdeburg auf Antikörper gegen SARS-CoV-2) is a longitudinal, regional cohort study to assess the seroprevalence of COVID-19 in blood donors from Magdeburg (Capital of Saxony-Anhalt) and surrounding areas. We consider blood donors as a surrogate for the healthy, working-age population of Saxony-Anhalt. The study primarily aims to measure the prevalence and kinetics of IgG antibodies against SARS-CoV-2 in first time and repeat blood donors over a period of 21 months. The study explores four survey periods of three to four months each (January–April 21, July–October 21, February–April 22, July–October 22). At each visit, we will assess the attitude towards vaccination, the antibody response following vaccination, as well as undesired vaccination effects. Furthermore, we will collect data on occupational activities, housing conditions and the frequency of family and other social contacts. Discussion: The SeMaCo study extends the spectrum of seroepidemiological investigations in Germany. A longitudinal observation with repeated testing and serial interviews can provide a more accurate view on the dynamics of COVID-19 prevalence and spread than repeated cross-sectional studies. Based on interim results from similar studies, we expect a seroprevalence of SARS-CoV-2 antibodies below 5% in the first survey period. SeMaCo will influence policy decisions and preventative measures.

Viral RNA Metagenomics of Hyalomma Ticks Collected from Dromedary Camels in Makkah Province, Saudi Arabia.

Arthropod-borne infections are a medical and economic threat to humans and livestock. Over the last three decades, several unprecedented viral outbreaks have been recorded in the Western part of the Arabian Peninsula. However, little is known about the circulation and diversity of arthropod-borne viruses in this region. To prepare for new outbreaks of vector-borne diseases, it is important to detect which viruses circulate in each vector population. In this study, we used a metagenomics approach to characterize the RNA virome of ticks infesting dromedary camels (Camelus dromedaries) in Makkah province, Saudi Arabia. Two hundred ticks of species Hyalomma dromedarii (n = 196) and Hyalomma impeltatum (n = 4) were collected from the Alkhurma district in Jeddah and Al-Taif city. Virome analysis showed the presence of several tick-specific viruses and tick-borne viruses associated with severe illness in humans. Some were identified for the first time in the Arabian Peninsula. The human disease-associated viruses detected included Crimean Congo Hemorrhagic fever virus and Tamdy virus (family Nairoviridae), Guertu virus (family Phenuiviridae), and a novel coltivirus that shares similarities with Tarumizu virus, Tai forest reovirus and Kundal virus (family Reoviridae). Furthermore, Alkhurma hemorrhagic virus (Flaviviridae) was detected in two tick pools by specific qPCR. In addition, tick-specific viruses in families Phenuiviridae (phleboviruses), Iflaviridae, Chuviridae, Totiviridae and Flaviviridae (Pestivirus) were detected. The presence of human pathogenetic viruses warrants further efforts in tick surveillance, xenosurveillence, vector control, and sero-epidemiological investigations in human and animal populations to predict, contain and mitigate future outbreaks in the region.

Characteristics Associated with Olfactory and Taste Disorders in COVID-19

Introduction: Olfactory and taste disorders (OTDs) have been reported in COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the mechanisms of which remain unclear. We conducted a detailed analysis of OTDs as part of 2 seroepidemiological investigations of COVID-19 outbreaks. Methods: Two retrospective cohort studies were conducted in a high school and primary schools of Northern France following a COVID-19 epidemic in February-March 2020. Students, their relatives, and school staff were included. Anti-SARS-CoV-2 antibodies were identified using a flow-cytometry-based assay detecting anti-S IgG. Results: Among 2,004 participants (median [IQR] age: 31 [11–43] years), 303 (15.2%) tested positive for SARS-CoV-2 antibodies. OTDs were present in 91 (30.0%) and 92 (30.3%) of them, respectively, and had 85.1 and 78.0% positive predictive values for SARS-CoV-2 infection, respectively. In seropositive participants, OTDs were independently associated with an age above 18 years, female gender, fatigue, and headache. Conclusion: This study confirms the higher frequency of OTDs in females than males and adults than children. Their high predictive value for the diagnosis of COVID-19 suggests that they should be systematically searched for in patients with respiratory symptoms, fever, or headache. The association of OTDs with headache, not previously reported, suggests that they share a common mechanism, which deserves further investigation.

Screening for SARS-CoV-2: Health Policy Implications in Low- and Middle-Income Countries

Screening for SARS-CoV-2: Health Policy Implications in Low- and Middle-Income Countries

Validation and field evaluation of a competitive inhibition ELISA based on the recombinant protein tSAG1 to detect anti-Neospora caninum antibodies in sheep and goats

Neospora caninum is a protozoan parasite that causes abortion and reproductive failure in small ruminants. We validated and evaluated under field conditions a competitive inhibition ELISA based on the truncated SAG1 protein (tSAG1) from N. caninum for the detection of anti-N. caninum antibodies in sheep and goat flocks. The assay was validated using 80 positive and 142 negative serum samples from sheep and goats analyzed by IFAT and immunoblot (IB). ciELISAtSAG1 was then used to evaluate the prevalence of anti-N. caninum antibodies in 1449 goats from 143 flocks and 385 sheep from 40 flocks and compared to IFAT. The prevalence of anti-Toxoplasma gondii antibodies was evaluated by IFAT. The ciELISAtSAG1 cut-off was ≥ 36 percent inhibition, with a diagnostic sensitivity of 100.0 % (95 % CI = 95.4–100.0 %) and a diagnostic specificity of 98.6 % (95 % CI = 95.0–99.8 %) relative to the agreement between IFAT and IB. The field evaluation revealed a concordance between ciELISAtSAG1 and IFAT of 97.4 %, with an agreement (κ) of 0.90 for sheep sera, and a concordance of 96.5 % with κ = 0.85 for goat sera. The overall prevalence of anti-N. caninum antibodies in sheep was 14.3 % by IFAT and 15.8 % by ciELISAtSAG1. In goats, prevalence was 12.9 % by IFAT and 14.6 % by ciELISAtSAG1. The overall prevalence of anti-T. gondii antibodies was 28.8 % in goats and 43.8 % in sheep. The ciELISAtSAG1 could be useful for large-scale detection of anti-N. caninum antibodies in sheep and goats, and for seroepidemiological investigations due to its appropriate sensitivity and specificity, and the simplicity of production.

SARS-CoV-2-IgG response is different in COVID-19 outpatients and asymptomatic contact persons.

Commercially available immunoassays have been developed for sensitive and specific detection of antibodies against SARS-CoV-2. While a fast and reliable IgG response has been reported for samples from hospitalized COVID-19 patients, less is known about ambulatory patients. We evaluated the SARS-CoV-2-IgG response by the Anti-SARS-CoV-2-ELISA IgG (Euroimmun) in a defined cohort of SARS-CoV-2-PCR-confirmed outpatients and asymptomatic contact persons including 137 serum samples from PCR-confirmed outpatients (n = 111) and asymptomatic but PCR-positive contact persons (n = 26) sent to our laboratory as part of routine diagnostics for determination of SARS-CoV-2-IgG. Overall positivity rate for SARS-CoV-2-IgG was 81.1 % in outpatients (irrespective of sampling before or after day 21 after onset of symptoms) but significantly lower in asymptomatic contact persons (15.4 %, p < 0.0001). In contact persons without symptoms the ct values of the PCR assays were significantly higher (5-7 threshold cycles) than in outpatients, and ct values were significantly negative correlated to the SARS-CoV-2-IgG ratio, suggesting a lower viral load as a possible explanation for lower rate of seropositivity. In summary, our study shows that serological response to SARS-CoV-2 in outpatients including asymptomatic persons is less pronounced than in hospitalized patients. Further controlled studies are urgently needed to determine serological response in outpatients and asymptomatic persons since this is the main target population for seroepidemiological investigations.

Development and application of a novel ELISA for detecting antibodies against group I fowl adenoviruses.

Since 2015, outbreaks of hepatitis-hydropericardium syndrome (HPS) caused by a novel genotype of fowl adenovirus 4 (FAdV-4) infection have created serious economic losses in China. Given that other serotypes of hypervirulent FAdVs have also been reported in poultry around the world, a common ELISA for all serotypes within the group I fowl adenoviruses (FAdV-I) is urgently needed, especially for clinical epidemic serotypes. In this study, we used high purity and concentration virions of FAdV-4 and developed a common ELISA for detecting antibodies against 12 FAdV-I serotypes. The developed ELISA was able to distinguish between antibodies against FAdV-I, FAdV-III, and other heterologous viruses without any cross-reaction. Furthermore, the ELISA showed higher sensitivity than the FAdV-1-based ELISA to the novel FAdV-4 found in China. Moreover, since there are no commercial vaccines against FAdVs in China, the ELISA was applied to detect sera samples from specific pathogen-free chickens inoculated with inactivated FAdV-1, FAdV-4, and FAdV-8a. The assay showed high sensitivities for all three detected serotypes within FAdV-I. In conclusion, a novel, common ELISA for FAdV-I was developed in this study and could be a powerful tool for seroepidemiological investigations and FAdVs vaccine development.

Evaluation of serological cross-reactivity between yellow fever and other flaviviruses

ObjectivesThis study was performed to determine whether neutralizing antibodies against yellow fever virus (YFV) generated by YFV vaccine could interfere in the specificity of dengue virus (DENV) and Zika virus (ZIKV) IgG ELISA tests. MethodsSeventy-nine pairs of serum samples (pre- and post-vaccination), collected during the years 1997–1998 from children with no history of yellow fever disease who had been vaccinated against YFV, were tested. The seroconversion post-vaccination was evaluated through plaque reduction neutralization test (PRNT), and four different commercial ELISA kits were used for the detection of DENV and ZIKV IgG antibodies. ResultsA cross-reactivity rate of 3.9% with DENV IgG antibodies was found only with the Dengue Virus IgG Dx Select kit (Focus Diagnostics). ConclusionsAs several countries have local transmission of multiple arboviruses, the absence of cross-reactivity or minimum cross-reactivity of YFV neutralizing antibodies with DENV and ZIKV antigens is a relevant finding, since the interpretation of sero-epidemiological investigations would be seriously impacted in many regions where YFV vaccination is mandatory.

Sheep pestivirus in Morocco: sero-epidemiological and molecular study

The present study is the first to investigate Border disease caused by the sheep pestivirus (SPV) in sheep herds in Morocco. Sero-epidemiological investigations were carried out in six regions of...

Small ruminant lentiviruses in goats in southern Italy: Serological evidence, risk factors and implementation of control programs

Small ruminant lentiviruses (SRLVs) can drastically affect milk production in goat flocks and only an early detection can control and prevent their spread. Since SRLVs are responsible for persistent infections, antibody screening is the most valuable tool to identify infected animals. ELISA is recommended as the election test both for its sensitivity and for its ability to detect low antibody titers, thus identifying infected animals earlier than agar gel immunodiffusion (AGID). In the present study, an investigation was conducted to assess the SRLV seroprevalence in goat flocks in southern Italy and a transversal comparative study was carried out through the analysis of the possible risk factors influencing SRLV spread. A total of 4800 sera from 1060 flocks were analyzed and overall seroprevalences of 18,64% and 51,69% at animal and herd levels, respectively, were observed. Both the region and the herd production systems were able to affect seroprevalence, differently from the herd size, probably because the mean number of goats per herd is low and the semi-intensive management is similar regardless of the dimensional class of each herd. In particular, meat producing herds showed the higher seroprevalence, as a result of the poor sanitation and low animal monitoring in comparison to milk producing herds, where animals are managed twice daily and the relationship between dams and kids is checked to guarantee an adequate quantitative/qualitative milk yield. In the absence of vaccines or effective treatments, health preventive management and seroepidemiological investigations are the only successful approach to restrict SRLV spread as observed in countries were official/voluntary control programs are carried out.

Seroepidemiological and molecular investigations of infections with Crimean–Congo haemorrhagic fever virus in Kazakhstan

ObjectivesThe aim of this study was to detect the seroprevalence of Crimean–Congo haemorrhagic fever virus (CCHFV) in patients with fever of unknown origin (FUO) in endemic (Kyzylorda) and non-endemic (Almaty) oblasts of Kazakhstan. MethodsPaired serum samples from 802 patients with FUO were collected. Serum samples were investigated by ELISA to detect IgG and IgM antibodies against CCHFV. Sera with suspected acute infection were further investigated by RT-PCR to detect the viral RNA. ResultsIgG antibodies were detected in 12.7% of the sera from both oblasts. Acute infection was shown by IgM ELISA in four patients from Kyzylorda, with only one developing severe CCHF. Viral RNA was found by RT-PCR in the other three patients’ sera. Phylogenetic analysis of partial L and S segments revealed CCHFV genotype Asia 2 and a possible reassortment between the genotypes Asia 1/Asia 2. Animal husbandry, such as working with cattle and horses, was significantly associated with CCHFV seropositivity. ConclusionsThe antibodies and viral RNA detected in sera indicate that mild or even asymptomatic CCHFV infections are presented in Kazakhstan. This study describes the circulation of CCHFV in the so far non-endemic Almaty oblast for the first time. In conclusion, physicians treating patients with FUO in Kazakhstan should be aware of mild CCHF.

Historical Perspective of Arboviruses in Mozambique and Its Implication for Current and Future Epidemics.

Mozambique is a tropical country situated in the Southern part of Africa, a region where data on the burden and epidemiology of arbovirus is presently quite scarce although the frequency of outbreaks caused by arboviruses is rapidly increasing. Outbreaks of dengue fever have been reported in Mozambique, Angola and Tanzania and a recent unprecedented outbreak of Yellow fever has been recorded in Angola. These new outbreaks collectively suggest that arboviruses, and specifically flavivirus infections, are endemic in Mozambique.Although recent data on arbovirus activity is scarce, the work of Kokernot et al. [R.H. Kokernot, K.C. Smithburn, A.F. Gandara, B.M. Mc'Intosh and C.S. Heymann Anais Inst Med Trop (1960), 17:201-230] describes seroepidemiological and entomological studies carried out in several parts of Mozambique during the 1950s. Complementary seroepidemiological investigations on arboviruses that were conducted in the early 1980s also found serological evidence of several arboviruses which included Dengue, Chikungunya, Zika, Rift Valey Fever, Sinbdis virus, Wesselsbron, Bunyamwera, Pongola and Bawamba Fever and Yellow Fever.Notably the first description of Chikungunya virus in 1952-1953 in Tanzania also included reported cases in northern Mozambique. Furthermore, DENV serotype 3 was for the first time described in northern Mozambique in 1984 and 1985. Since several arboviral infections result in acute self limiting fever they have remained unsuspected for several decades. However, it is well known that during the 1980's intensive malaria control initiatives which included massive distribution of bed nets, community education and indoor and outdoor spraying campaigns were implemented. It is possible that these measures may have influenced the epidemiology of arboviruses. However, the impact of these interventions in controlling the spread of arboviruses is not known.In conclusion, the old literature on arboviruses in Mozambique is relevant for assessing the gaps and current risk of occurrence of these pathogens at the region, particularly in a time in which they are spreading worldwide.