Period Of Viremia Research Articles

Molecular Diagnosis of Phlebovirus riftense Infection Using an L-Segment-Based Real-Time RT-PCR Method.

Rift Valley fever (RVF) is one of the main vector-borne zoonotic diseases that affects a wide range of ruminants and humans in Africa and the Arabian Peninsula.Several techniques involving cell culture and molecular biology methods have been developed to diagnose RVF infection. Success partly relies on sending samples to a national or reference laboratory in good conditions and having the capacity to perform the appropriate diagnostic test in the matrix of interest during the period of viremia where high loads of viral particles are present. Conventional and duplex/multiplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) assays are currently the most rapid and sensitive molecular tests for the detection and quantification of Rift Valley fever virus (RVFV) during outbreaks. The one-step real-time duplex RT-PCR technique that is detailed in this chapter is based on the L segment of RVFV. Results must be carefully validated and interpreted, taking into account the results of both positive and negative controls.

Construction of the First Russian Recombinant Live Attenuated Vaccine Strain and Evaluation of Its Protection Efficacy Against Two African Swine Fever Virus Heterologous Strains of Serotype 8.

Background/Objectives: The spread of African swine fever virus (ASFV) has led to major economic losses to pork worldwide. In Russia, there are no developed or registered vaccines against ASFV genotype II, which is associated with numerous ASFV outbreaks in populations of domestic pigs and wild boars in the country. Methods: We introduced deletions of the six MGF360 and MGF505 genes of the ASFV virulent Stavropol_01/08 strain, isolated in Russia in 2008. Results: We show here that this deletion did lead to full attenuation of the ASFV virulent Stavropol_01/08 strain. Animals intramuscularly inoculated with 104 HAD50 of ΔMGF360/505_Stav developed a strong immune response and short period of viremia (at 3-7 days post-inoculation). Recombinant ΔMGF360/505_Stav strain provides complete protection of pigs against the ASFV parental Stavropol_01/08 strain (103 HAD50). Therefore, in our experiment, we did not detect the genome of both the virulent and the recombinant strains in the blood and organs post-challenge with the Stavropol_01/08. In contrast, we found only partial protection (40%) of the ΔMGF360/505_Stav-immunized pigs against challenge with the ASFV heterologous Rhodesia strain. Additionally, the surviving animals had a prolonged fever, and their condition was depressed for most of the experiment. Conclusions: Thus, the ASFV recombinant ΔMGF360/505_Stav strain is the first live attenuated vaccine (LAV) in Russia that induces complete protection in pigs challenged with the highly virulent, epidemiologically relevant strains genotype II and serotype 8. However, this ASF LAV is not able to provide a high level of protection against other variants of serotype 8.

Analysis of Powassan Virus Genome Sequences from Human Cases Reveals Substantial Genetic Diversity with Implications for Molecular Assay Development.

Powassan virus (POWV) is an emerging tick-borne virus that causes severe meningoencephalitis in the United States, Canada, and Russia. Serology is generally the preferred diagnostic modality, but PCR on cerebrospinal fluid, blood, or urine has an important role, particularly in immunocompromised patients who are unable to mount a serologic response. Although the perceived poor sensitivity of PCR in the general population may be due to the biology of infection and health-seeking behavior (with short viremic periods that end before hospital presentation), limitations in assay design may also contribute. Genome sequences from clinical POWV cases are extremely scarce; PCR assay design has been informed by those available, but the numbers are limited. Larger numbers of genome sequences from tick-derived POWV are available, but it is not known if POWV genomes from human infections broadly mirror genomes from tick hosts, or if human infections are caused by a subset of more virulent strains. We obtained viral genomic data from 10 previously unpublished POWV human infections and showed that they broadly mirror the diversity of genome sequences seen in ticks, including all three major clades (lineage I, lineage II Northeast, and lineage II Midwest). These newly published clinical POWV genome sequences include the first confirmed lineage I infection in the United States, highlighting the relevance of all clades in human disease. An in silico analysis of published POWV PCR assays shows that many assays were optimized against a single clade and have mismatches that may affect their sensitivity when applied across clades. This analysis serves as a launching point for improved PCR design for clinical diagnostics and environmental surveillance.

OCORRÊNCIA DA FEBRE DO NILO EM EQUINOS NO BRASIL

West Nile Fever (WNF) is a zoonotic arbovirus caused by the West Nile Virus (WNV). It is a highly relevant topic in veterinary medicine in Brazil. It was first identified in Uganda in 1937 and the virus spread to Africa, Europe, the Middle East, Western Asia and Australia. In 1999, the virus reached the United States and has since spread throughout the Americas, becoming the arbovirus with the largest geographic distribution. The first signs of WNV in Brazil appeared in 1999, with positive results in birds and horses, with birds acting as sentinels for the disease. In 2014, the first human case was recorded in Piauí. As of 2018, cases in birds and horses have been confirmed in Espírito Santo. WNV, an RNA virus of the Flaviviridae family, is transmitted by the bite of mosquitoes of the Culex genus, and these mosquitoes become infected through infected birds during the viremic period. Birds are amplifying hosts and humans and horses are accidental hosts. In Brazil, climatic, environmental and socioeconomic characteristics contribute to the amplification of the virus. Diagnosis is made by demonstrating antiviral IgM by ELISA, or, post-mortem, with RT-PCR. Preventive measures involve the use of repellents and screens, in addition to the application of larvicides. In horses, the application of vaccines, although recommended, is not yet licensed in Brazil. This study analyzed the occurrence of West Nile Fever in horses in Brazil through a review of scientific articles. Searches were conducted in the Google Scholar, PUBMED and Scielo databases, published between 2004 and 2024. The research was supported by the following search criteria: “Nile Fever”, “equines” and “Brazil”, in Portuguese, and “West Nile Fever”, “horses” and “Brazil”, in English. It was found that horses are accidental or terminal hosts and, because it is little known, many times it is not reported or diagnosed, thus demonstrating the importance of further studies and dissemination of information about this disease.

Low Rate of Asymptomatic Dengue Infection Detected in Coastal Kenya Using Pooled Polymerase Chain Reaction Testing.

Asymptomatic dengue virus (DENV) infections have important public health implications but are challenging to identify. We performed a cross-sectional study of reverse transcription quantitative polymerase chain reaction on pooled sera of asymptomatic individuals from the south coast of Kenya at two time periods to identify cases of asymptomatic viremia. Among 2,460 samples tested in pools of 9 or 10, we found only one positive case (0.04% incidence). Although pooling of samples has the potential to be a cost-effective and time-efficient method for asymptomatic DENV detection, mass cross-sectional pooled testing may not provide accurate data on rates of asymptomatic infection, likely owing to a decrease in the sensitivity with pooling of samples, a short period of viremia, or testing in the absence of an outbreak.

Low-dose dengue virus 3 human challenge model: a phase 1 open-label study.

Dengue human infection models present an opportunity to explore the potential of a vaccine, anti-viral or immuno-compound for clinical benefit in a controlled setting. Here we report the outcome of a phase 1 open-label assessment of a low-dose dengue virus 3 (DENV-3) challenge model (NCT04298138), in which nine participants received a subcutaneous inoculation with 0.5 ml of a 1.4 × 103 plaque-forming unit per ml suspension of the attenuated DENV-3 strain CH53489. The primary and secondary endpoints of the study were to assess the safety of this DENV-3 strain in healthy flavivirus-seronegative individuals. All participants developed RNAaemia within 7 days after inoculation with peak titre ranging from 3.13 × 104 to 7.02 × 108 genome equivalents per ml. Solicited symptoms such as fever and rash, clinical laboratory abnormalities such as lymphopenia and thrombocytopenia, and self-reported symptoms such as myalgia were consistent with mild-to-moderate dengue in all volunteers. DENV-3-specific seroconversion and memory T cell responses were observed within 14 days after inoculation as assessed by enzyme-linked immunosorbent assay and interferon-gamma-based enzyme-linked immunospot. RNA sequencing and serum cytokine analysis revealed anti-viral responses that overlapped with the period of viraemia. The magnitude and frequency of clinical and immunologic endpoints correlated with an individual's peak viral titre.

Repurposing of Rutan showed effective treatment for COVID-19 disease

Previously, from the tannic sumac plant (Rhus coriaria), we developed the Rutan 25 mg oral drug tablets with antiviral activity against influenza A and B viruses, adenoviruses, paramyxoviruses, herpes virus, and cytomegalovirus. Here, our re-purposing study demonstrated that Rutan at 25, 50, and 100 mg/kg provided a very effective and safe treatment for COVID-19 infection, simultaneously inhibiting two vital enzyme systems of the SARS-CoV-2 virus: 3C-like proteinase (3CLpro) and RNA-dependent RNA polymerase (RdRp). There was no drug accumulation in experimental animals’ organs and tissues. A clinical study demonstrated a statistically significant decrease in the C-reactive protein and a reduction of the viremia period. In patients receiving Rutan 25 mg (children) and 100 mg (adults), the frequency of post-COVID-19 manifestations was significantly less than in the control groups not treated with Rutan tablets. Rutan, having antiviral activity, can provide safe treatment and prevention of COVID-19 in adults and children.Clinical Trial RegistrationClinicalTrials.gov, ID NCT05862883.

Prenatal Zika virus infection has sex-specific effects on infant physical development and mother-infant social interactions.

There is enormous variation in the extent to which fetal Zika virus (fZIKV) infection affects the developing brain. Despite the neural consequences of fZIKV infection observed in people and animal models, many open questions about the relationship between infection dynamics and fetal and infant development remain. To further understand how ZIKV affects the developing nervous system and the behavioral consequences of prenatal infection, we adopted a nonhuman primate model of fZIKV infection in which we inoculated pregnant rhesus macaques and their fetuses with ZIKV in the early second trimester of fetal development. We then tracked their health across gestation and characterized infant development across the first month of life. ZIKV-infected pregnant mothers had long periods of viremia and mild changes to their hematological profiles. ZIKV RNA concentrations, an indicator of infection magnitude, were higher in mothers whose fetuses were male, and the magnitude of ZIKV RNA in the mothers' plasma or amniotic fluid predicted infant outcomes. The magnitude of ZIKV RNA was negatively associated with infant growth across the first month of life, affecting males' growth more than females' growth, although for most metrics, both males and females evidenced slower growth rates as compared with control animals whose mothers were not ZIKV inoculated. Compared with control infants, fZIKV infants also spent more time with their mothers during the first month of life, a social behavior difference that may have long-lasting consequences on psychosocial development during childhood.

Detection of Hepatitis E Virus in Rabbits and Rabbit Meat from Slaughterhouses in Hebei Province of China.

Background: Hepatitis E virus (HEV) is a zoonotic pathogen. HEV has been found to be widely prevalent in rabbits. Its isolates are classified into HEV-3, rabbit subgenotype (HEV-3ra). The routes of human infection with HEV-3ra remain unclear; however, foodborne transmission is possible when asymptomatically infected animals enter the food chain. The prevalence of HEV infection in slaughtered rabbits and the presence of HEV in rabbit meat were evaluated in this study. Materials and Methods: In three slaughterhouses in Hebei province, China, samples of rabbit blood were collected during the slaughter process, and muscle, liver, and cavity juice were collected from the rabbit carcasses. Anti-HEV antibody in serum samples was detected using enzyme-linked immunosorbent assay. HEV RNA was tested in all samples by reverse transcription nested PCR (RT-nested PCR). The final amplicons of RT-nested PCR were sequenced and phylogenetically analyzed. Results: Of the 459 serum samples, 50 [10.9%, 95% confidence interval (CI): 8.1-13.7] were positive for anti-HEV antibody, and 17 (3.7%, 95% CI: 2.0-5.4) were positive for HEV RNA. HEV RNA was detected in 7 of 60 liver samples (11.7%, 95% CI: 3.3-20) and 2 cavity juice samples from semi-eviscerated carcasses, but was not detected in any muscle sample from either the eviscerated or semi-eviscerated carcasses. All the detected HEV strains belonged to HEV-3ra and related most closely with the rabbit HEV sequence previously reported in China. Conclusion: A portion of rabbits were in the viremia period of HEV infection at the slaughter age, resulting in the possibility of HEV carriage by rabbit carcass, particularly semi-eviscerated carcass containing liver. These findings suggest a potential risk of HEV transmission from raw rabbit products entering the food chain, whereas the presence of HEV appeared to be lower in the eviscerated carcass than in the semi-eviscerated carcass.

DENV-specific IgA contributes protective and non-pathologic function during antibody-dependent enhancement of DENV infection.

Dengue represents a growing public health burden worldwide, accounting for approximately 100 million symptomatic cases and tens of thousands of fatalities yearly. Prior infection with one serotype of dengue virus (DENV) is the greatest known risk factor for severe disease upon secondary infection with a heterologous serotype, a risk which increases as serotypes co-circulate in endemic regions. This disease risk is thought to be mediated by IgG-isotype antibodies raised during a primary infection, which poorly neutralize heterologous DENV serotypes and instead opsonize virions for uptake by FcγR-bearing cells. This antibody-dependent enhancement (ADE) of infection leads to a larger proportion of susceptible cells infected, higher viremia and greater immunopathology. We have previously characterized the induction of a serum IgA response, along with the typical IgM and IgG responses, during dengue infection, and have shown that DENV-reactive IgA can neutralize DENV and competitively antagonize IgG-mediated ADE. Here, we evaluate the potential for IgA itself to cause ADE. We show that IgG, but not IgA, mediated ADE of infection in cells expressing both FcαR and FcγRs. IgG-mediated ADE stimulated significantly higher pro-inflammatory cytokine production by primary human macrophages, while IgA did not affect, or slightly suppressed, this production. Mechanistically, we show that DENV/IgG immune complexes bind susceptible cells significantly more efficiently than DENV/IgA complexes or virus alone. Finally, we show that over the course of primary dengue infection, the expression of FcγRI (CD64) increases during the period of acute viremia, while FcγRIIa (CD32) and FcαR (CD89) expression decreases, thereby further limiting the ability of IgA to facilitate ADE in the presence of DENV. Overall, these data illustrate the distinct protective role of IgA during ADE of dengue infection and highlight the potential therapeutic and prognostic value of DENV-specific IgA.

Low transmission risk of African swine fever virus between wild boar infected by an attenuated isolate and susceptible domestic pigs.

African swine fever (ASF) is a lethal infectious disease that affects domestic and wild pigs. This complex virus has already affected five continents and more than 70 countries and is considered to be the main threat to the global swine industry. The disease can potentially be transmitted directly through contact with infectious animals, or indirectly by means of contaminated feed or environments. Nevertheless, the knowledge regarding the transmission patterns of different ASF virus isolates at the wildlife-livestock interface is still limited. We have, therefore, assessed the potential transmission of an attenuated ASF virus isolate between infectious wild boar and directly exposed domestic pig. We registered 3,369 interspecific interactions between animals, which were brief and mostly initiated by wild boar. The major patterns observed during the study were head-to-head contact owing to sniffing, thus suggesting a high probability of pathogen transmission. However, only one of the five domestic pigs had a short period of viremia and became serologically positive for ASF virus antibodies. It was additionally discovered that the wild boar did not transmit the virulent virus isolate to the domestic pigs, which suggests that the presence of attenuated ASF virus isolates in affected areas may control the spreading of other more virulent isolates. These outcomes may help make decisions related to large-scale targeted management actions against ASF in field conditions.

Development of a novel Macaque-Tropic HIV-1 adapted to cynomolgus macaques.

Macaque-tropic HIV-1 (HIV-1mt) variants have been developed to establish preferable primate models that are advantageous in understanding HIV-1 infection pathogenesis and in assessing the preclinical efficacy of novel prevention/treatment strategies. We previously reported that a CXCR4-tropic HIV-1mt, MN4Rh-3, efficiently replicates in peripheral blood mononuclear cells (PBMCs) of cynomolgus macaques homozygous for TRIMCyp (CMsTC). However, the CMsTC challenged with MN4Rh-3 displayed low viral loads during the acute infection phase and subsequently exhibited short-term viremia. These virological phenotypes in vivo differed from those observed in most HIV-1-infected people. Therefore, further development of the HIV-1mt variant was needed. In this study, we first reconstructed the MN4Rh-3 clone to produce a CCR5-tropic HIV-1mt, AS38. In addition, serial in vivo passages allowed us to produce a highly adapted AS38-derived virus that exhibits high viral loads (up to approximately 106 copies ml-1) during the acute infection phase and prolonged periods of persistent viremia (lasting approximately 16 weeks postinfection) upon infection of CMsTC. Whole-genome sequencing of the viral genomes demonstrated that the emergence of a unique 15-nt deletion within the vif gene was associated with in vivo adaptation. The deletion resulted in a significant increase in Vpr protein expression but did not affect Vif-mediated antagonism of antiretroviral APOBEC3s, suggesting that Vpr is important for HIV-1mt adaptation to CMsTC. In summary, we developed a novel CCR5-tropic HIV-1mt that can induce high peak viral loads and long-term viremia and exhibits increased Vpr expression in CMsTC.

High urinary CXCL10/Cr with onset of Burkitt lymphoma in a pediatric kidney transplant recipient

Urinary CXCL10/Cr is a promising diagnostic tool for early detection of TCMR in pediatric transplant recipients, and most studies focus on its utility in the context of localized allograft inflammation thus far. Other sources of inflammation that may be detected by CXCL10 are less clear. We present a case review of a patient with BL, who was enrolled in a prospective trial of urinary CXCL10 monitoring. To evaluate the potential confounding, we tested for association of CXCL10/Cr and EBV viral load in a prospective cohort of pediatric transplant recipients with serial testing for urinary CXCL10/Cr. This report describes a 15-year-old boy, 3.5 years post-transplant with chronic EBV viremia, stable kidney function and no history of rejection. Urinary CXCL10/Cr level increased acutely to 79.43 ng/mmol, 0.8 months prior to onset of BL, identified by a surge in EBV viral load. In a national cohort of 97 pediatric kidney transplant recipients, there was no association between urinary CXCL10/Cr with EBV viral loads when comparing periods of pre-viremia (5.8± 9.2ng/mmol) to active viremia (4.0± 5.3ng/mmol) and periods of active viremia (7.1± 8.9ng/mmol) to post-viremia (4.4± 9.8ng/mmol). Acute rise in urinary CXCL10/Cr was associated with onset of graft-associated BL. We were not able to confirm a general association of EBV viral load and urinary CXCL10. As non-invasive monitoring is implemented using biomarkers like CXCL10 in the clinic, attention will be needed to identify other uncommon, potential sources of CXCL10 elevation.

Evaluation of Molecular Test for the Discrimination of "Naked" DNA from Infectious Parvovirus B19 Particles in Serum and Bone Marrow Samples.

Low levels of parvovirus B19 (B19V) DNA can be detected in the circulation and in different tissue of immunocompetent individuals for months or years, which has been linked to inflammatory diseases such as cardiomyopathy, rheumatoid arthritis, hepatitis, and vasculitis. However, the detection of B19V DNA does not necessarily imply that infectious virions are present. This study aimed to evaluate the method based on the Benzonase® treatment for differentiation between the infectious virions from “naked” DNA in serum and bone marrow (BM) samples to be useful for the B19V routine diagnosis. In addition, we estimated the period of viremia and DNAemia in the sera and bone marrow of nonhuman primates experimentally infected with B19V. Serum samples from ten patients and from four cynomolgus monkeys experimentally infected with B19V followed up for 60 days were used. Most of the human serum samples became negative after pretreatment; however, only decreased viral DNA loads were observed in four patients, indicating that these samples still contained the infectious virus. Reduced B19V DNA levels were observed in animals since 7th dpi. At approximately 45th dpi, B19V DNA levels were below 105 IU/mL after Benzonase® pretreatment, which was not a consequence of active B19V replication. The test based on Benzonase® pretreatment enabled the discrimination of “naked DNA” from B19V DNA encapsidated in virions. Therefore, this test can be used to clarify the role of B19V as an etiological agent associated with atypical clinical manifestations.

SARS-CoV-2 Booster Vaccination for Participants in "HIV Cure"-Related Clinical Trials.

SARS-CoV-2 Booster Vaccination for Participants in "HIV Cure"-Related Clinical Trials.

Detection and localization of atypical porcine pestivirus in the testicles of naturally infected, congenital tremor affected piglets.

Atypical porcine pestivirus (APPV) belongs to the genus Pestivirus within the family Flaviviridae. Recently, APPV has been identified as the causative agent of congenital tremor (CT) type AII. The disease is a neurological disorder that affects newborn piglets and is characterized by generalized trembling of the animals and often splay legs. CT is well known worldwide, and the virus seems to be highly prevalent in major swine producing areas. However, little is known about the epidemiology of the infection, transmission and spread of the virus between herds. Here, we show the high prevalence of APPV in processing fluid samples collected from Hungarian pig herds which led us to investigate the cellular targets of the virus in the testicles of newborn piglets affected by CT. By the development of an RNA in situ hybridization assay and the use of immunohistochemistry on consecutive slides, we identified the target cells of APPV in the testicle: interstitial Leydig cells, peritubular myoid cells and smooth muscle cells of medium‐sized arteries. Previous studies have shown that APPV can be found in the semen of sexually mature boars suggesting the role of infected boars and their semen in the transmission of the virus similar to many other members of the Flaviviridae family. As in our case, the virus has not been identified in cells beyond the Sertoli cell barrier, further studies on infected adult boars’ testicles and other reproductive glands are needed to analyze the possible changes in the cell tropism of APPV that might contribute to its prolonged extraction by the semen beyond the period of viraemia.

Recently acquired hepatitis C virus infection among people living with human immunodeficiency virus at a university hospital in Taiwan.

BACKGROUNDLittle is known about the engagement in hepatitis C virus (HCV) care and completion of HCV treatment in people living with human immunodeficiency virus (HIV) (PLWH) who have HCV coinfection in the Asia-Pacific region. Examining the HCV care cascade can identify barriers to the completion of HCV treatment and facilitate achievement of HCV micro-elimination in PLWH.AIMTo investigate the care cascade of incident HCV infections among PLWH in Taiwan.METHODSPLWH with incident HCV infections, defined as HCV seroconversion, were retrospectively identified by sequential anti-HCV testing of all archived blood samples at National Taiwan University Hospital between 2011 and 2018. All PLWH with incident HCV infections were followed until December 31, 2019. The care cascade of HCV examined included all incident HCV-infected patients, the percentages of anti-HCV antibodies detected by HIV-treating physicians in clinical care, plasma HCV RNA load tested, HCV RNA positivity diagnosed, referral to treatment assessment made, anti-HCV treatment initiated, and sustained virologic response achieved. Those who had HCV seroconversion during the interferon (IFN) era (2011–2016) and the direct-acting antiviral (DAA) era (2017–2018) were analyzed separately. The duration of HCV viremia—from the date of seroconversion to viral clearance by treatments or until the end of observation—and the incidence of sexually transmitted infections (STIs) during the HCV viremic period were estimated.RESULTSDuring the study period, 287 of 3495 (8.2%) PLWH (92.3% being men who have sex with men) who were HCV-seronegative at baseline developed HCV seroconversion by retrospective testing of all archived blood samples. Of the 287 incident HCV infections, 277 (96.5%) had anti-HCV antibodies detected by HIV-treating physicians, 270 (94.1%) had plasma HCV RNA determined and 251 (87.5%) tested positive for HCV RNA. Of those with HCV viremia, 226 (78.7%) were referred to treatment assessment, 215 (74.9%) initiated anti-HCV treatment, and 202 (70.4%) achieved viral clearance. Compared with that in the IFN era, the median interval from HCV seroconversion by retrospective testing to detection of HCV seropositivity by HIV-treating physicians was significantly shorter in the DAA era {179 d [interquartile range (IQR) 87-434] vs 92 d (IQR 57-173); P < 0.001}. The incidence rate of STIs in the DAA vs the IFN era was 50.5 per 100 person-years of follow-up (PYFU) and 38.5 per 100 PYFU, respectively, with an incidence rate ratio of 1.31 (95% confidence interval 0.96-1.77), while the duration of HCV viremia was 380 d (IQR 274-554) and 735 d (IQR 391-1447) (P < 0.001), respectively.CONCLUSIONWhile anti-HCV therapies are effective in achieving viral clearance, our study suggests more efforts are needed to expedite the linkage of PLWH diagnosed with incident HCV infections to HCV treatment.

Нейтропенії в дітей: набуті нейтропенії

Neutropenia is defined as a reduction in the absolute neutrophil count (ANC) below 1,500 cells/mcl in the blood. Neutropenia is a common laboratory finding in children. It is important to distinguish transient and benign causes from severe congenital neutropenia. Neutropenia can be classified in asymptomatic (mild), moderate, and severe form, the susceptibility to infection depending on ANC. Neutropenia can be either acquired or congenital. Infection, drugs, and immune disorders are the most common acquired causes while congenital causes are rare and confined mostly to infants and children. Transient neutropenia often accompanies viral infections in children, manifested in the period of acute viremia. Young children are characterized by autoimmune neutropenia (AIN), which has a benign course and a favorable prognosis. Autoimmune neutropenia is characterized by a decrease in the number of neutrophils as a result of the destruction of neutrophils in the peripheral blood by antineutrophil antibodies. The duration of AIN is usually 3–5 years. This is a self-limiting disease that in most cases does not require treatment. Despite the benign course, serious infectious complications can occur. Treatment of myeloid growth factors should be started after a previous bone marrow aspiration biopsy in children with severe infections or requiring surgical intervention. High doses of intravenous immunoglobulin and corticosteroids may be effective in treating AIN in patients with life-threating infections. The danger to the patient depends on the etiology, ANC and bone marrow status. The risk of infections is significantly increased in patients with ACN less than 500 cells/μ1. The most common loci of infections include the oral mucosa, skin, perirectal area, perineum. Oral ulcers and gingivitis are characteristic signs of clinically significant neutropenia, requiring the exclusion of its congenital causes. Severe infections in patients with neutropenia are caused by pyogenic or intestinal bacteria and Candida species. It is important to distinguish between transient or benign causes and severe congenital neutropenia or neutropenia associated with serious haematological or systemic disease. Clarification of the cause of neutropenia is important for determining management and prognosis. No conflict of interest was declared by the author. Key words: neutropenia, children, immunodeficiency, autoimmune neutropenia.

Seroprevalence of porcine reproductive and respiratory syndrome virus on swine farms in a tropical country of the Middle Americas: the case of Costa Rica

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the swine industry worldwide. Little is known regarding the epidemiology of this infection in tropical countries. To address this problem in Costa Rica, a seroepidemiological study was carried out in two phases. In the first phase, a pilot study was conducted in nine farms with the clinical diagnosis of PRRSV. In total, 265 pig serum samples were collected from animals ranging in age from 1 to 15 weeks of age. This study aimed to establish the duration of maternal immunity in piglets, to identify the period of viremia, and to determine when seroconversion occurs. In the second phase, a cross-sectional serology study was performed on a representative sample of the Costa Rican national herds in the second phase. The twenty-five selected farms represent all provinces and were classified according to herd size (100 to 2000 sows). In each farm, pigs aged 8, 10, and 12 weeks were sampled, as well as gilts based on the pilot study. In total 1281 pigs were sampled across all 25 farms. The aim of the cross-sectional study was to quantify the seroprevalence of PRRSV in Costa Rican pig farms and to describe its geographical distribution in this tropical country. The prevalence of positive farms was 44% (11/25), and these farms were located in six of the seven provinces of Costa Rica. Overall, 58% (344/596) of the pigs were seropositive to PRRSV. The age of the pigs and the ecozone where farms were located were significantly related with PRRSV seroprevalence in animals and herds, respectively.

Mosquito-Borne Viral Infections in the Krasnodar Territory ~ Risks of Autochthonous Cases of the Disease

Introduction. Global climate changes affect the habitats of insects, including mosquitoes, which are carriers of dangerous natural focal infections. When mosquitos develop new territories, they create a potential threat to people who find themselves in these areas. In the Krasnodar Region, a stable population of Ae. albopictus mosquitoes was formed in the 21st century. These mosquitoes are carriers of many viral pyrrhoid-focal infections, such as Dengue, Chikungunya, Zika fever and Yellow fever. Estimations of biological, epidemiological and cultural data can help to answer the question of the probability of occurrence of autochthonous cases of infection.Aim. To estimate the probability of occurrence of autochthonous cases of viral infections carried by Ae. albopictus mosquitoes on the territory of the Black Sea coast of the Krasnodar territory. For the review, we used scientific publications describing the occurrence of autochthonous diseases in similar climate zones inhabited by Ae. albopictus mosquitoes, the biology of these mosquitoes, as well as official reports of the sanitary services of Europe and the Russian Federation. A stable population of Ae. albopictus mosquitoes has formed on the Black Sea coast of the Krasnodar Territory. The local climate, including the temperature range is favourable for active reproduction of vectors and autochthonous transmission of viral infection.Conclusion. Despite the favourable conditions for the release of mosquitoes and the formation of a stable population, autochthonous transmission requires the introduction of the source of infection during the viremia period to infect the mosquito population. In recent years, isolated cases of such drifts have been reported in the Krasnodar Territory, which indicates a low probability of local cases of transmission. However, with the development of the tourism sector, the flow of tourists from endemic areas will inevitably increase. In addition, the increase in the well-being of the population, trips to these countries will become more frequent this may well increase the risk of transmission of viral infections by local mosquitoes. In any case, the weakening of epidemic control of mosquitoes and medical surveillance of imported cases of tropical fevers will have serious consequences.