Human Papillomavirus (HPV) Prevalence, Temporal Dynamics and Association with Abnormal Cervical Cytology Findings in Women from Croatia: Is there a Compounding Effect of Low-Risk/High-Risk HPV Co-Infection?

BACKGROUND: Human papillomavirus (HPV) is a major risk factor for cervical dysplasia and invasive cervical cancer; therefore, regular screening by cervical smear cytology or HPV testing is recommended. We aimed to determine the overall and risk group-specific HPV prevalence, age distribution, and temporal trends and to appraise the correlation of HPV positivity with abnormal cervical cytological findings. METHODS: This retrospective, single-center study involved a total of 751 women (aged 18 - 67) concurrently subjected to HPV DNA testing and cervical cytology evaluation over a 10-year period in Zagreb, Croatia. Digene HC2 HPV DNA test (Qiagen Corporation, USA) was employed in screening specimens for both low-risk and high-risk HPV risk groups. The cytology was reported using the Bethesda system and in accordance with uniform classification of uterine cervix cytological findings in Croatia "Zagreb 2002". Statistical significance was set at p < 0.05. RESULTS: The overall HPV prevalence in our study population was 48.6%, and the 18 - 30 age group presented with the highest infection burden (p = 0.046). A decrease in low-risk and high-risk mono-positivity has been observed over the 10-year period; conversely, there was a significant increase in low-risk/high-risk co-positivity (p = 0.007). Low-risk/high-risk HPV co-infection resulted in a compounding effect which increased the occurrence of abnormal cells, HPV-associated changes and low grade squamous intraepithelial lesions (LSIL/cervical intraepithelial neoplasia grade I) in cervical cytology when compared to mono-infection with either low-risk or high-risk HPV. On the other hand, such effect has not been demonstrated for high grade squamous intraepithelial lesions (HSIL/ cervical intraepithelial neoplasia grades II and III). CONCLUSIONS: The overall HPV prevalence in female outpatients was high, underscored with rising co-positivity rates. Such co-infection with both low-risk and high-risk HPV (predominantly seen in women younger than 30) can exhibit a compounding effect in the occurrence of cytological abnormalities and low grade squamous intra-epithelial lesions (LSIL), which has to be considered in future diagnostic and screening algorithms.

Viral pathogens associated with acute respiratory illness in hospitalized adults and elderly from Zagreb, Croatia, 2016 to 2018.

AIMS: To investigate the viral etiology of acute respiratory infection (ARI) in hospitalized adults and elderly patients in Croatia, compare the prevalence of detected viruses, and to determine clinical characteristics and seasonal occurrence of investigated infections. METHODS: From January 2016 to June 2018, a total of 182 adult patients presented with symptoms of ARI and admitted to the hospital were tested for 15 respiratory viruses by multiplex reverse-transcription polymerase chain reaction. Clinical data were collected by retrospective analysis of the patient's chart. RESULTS: A virus was identified in 106 (58.5%) of the patients. The most commonly detected virus was influenza virus (41.5%), followed by respiratory syncytial virus (13.8%), human metapneumovirus (13.0%), parainfluenza viruses (12.2%), rhinoviruses (11.4%), adenovirus and coronaviruses with equal frequencies (3.3%), and enterovirus (1.6%). The serum level of C-reactive protein and white blood cell count were significantly lower in patients with respiratory viruses identified when compared with those in whom no virus was detected (P < 0.001 and P = 0.007, respectively). There were no differences in clinical symptoms according to the type of the detected virus, except for more frequent illness exposure recall for influenza infection ( P = 0.010). Influenza, parainfluenza, and pneumoviruses were detected mostly in winter months, while rhinoviruses in autumn and spring. CONCLUSIONS: In addition to influenza, pneumoviruses, rhinoviruses, and parainfluenza viruses play an important role in etiology of ARIs in adults. Fast and accurate laboratory diagnosis for respiratory viruses in routine practice is needed for clinicians optimally manage patients with ARI and potentially avoid the unnecessary use of antimicrobial drugs.

An Outbreak of Human Parainfluenza Virus 3 (Phylogenetic Subcluster C5) Infection among Adults at a Residential Care Facility for the Disabled in Croatia, 2018.

INTRODUCTION: Although highly pertinent for children, outbreaks of human parainfluenza virus (HPIV) may cause up to 15% of all respiratory illnesses in adults and predispose them to serious adverse outcomes, with HPIV serotype 3 (HPIV3) being the most common. This study represents the first report of an HPIV3 outbreak among adults at a long-term health-care facility in Croatia. METHODS: A retrospective study was conducted to investigate an outbreak of acute respiratory infection (ARI) at a single residential care facility for the disabled in Croatia. Demographic, epidemiological, and clinical data were collected for all residents, while hospitalized patients were appraised in detail by laboratory/radiological methods. Multiplex PCR for respiratory viruses and sequencing was performed. Partial HPIV3 HN 581 nt sequences were aligned with HPIV3 sequences from the GenBank database to conduct a phylogenetic analysis, where different bioinformatic approaches were employed. RESULTS: In late June 2018, 5 of the 10 units at the facility were affected by the outbreak. Among the 106 residents, 23 (21.7%) developed ARI, and 6 (26.1%) of them were hospitalized. HPIV3 was identified in 18 (73%) of the residents and 5 (83%) of the hospitalized individuals. Isolated HPIV3 strains were classified within the phylogenetic subcluster C5 but grouped on 2 separate branches of the phylogenetic tree. During the entire outbreak period, none of the institution's employees reported symptoms of ARI. CONCLUSIONS: Our study has shown that this health care-associated outbreak of HPIV3 infection could have been linked to multiple importation events. Preventive measures in curbing such incidents should be enforced vigorously.

High Detection Rates of Human Bocavirus in Infants and Small Children with Lower Respiratory Tract Infection from Croatia.

BACKGROUND: Human bocavirus (HBoV) is known to cause lower respiratory tract infections (LRTI) in children and may result in substantial morbidity and mortality. The aim of this study was to determine HBoV prevalence among hospitalized infants and small children with acute LRTI in Zagreb, Croatia, as well as to evaluate HBoV DNA quantity in samples in relation to the patients' age and co-infection with other respiratory viruses. METHODS: During winter season 2016/2017, a total of 295 children younger than three years of age who were admitted to hospitals with LRTI were tested for the presence of HBoV, respiratory syncytial virus (RSV), adenovirus (ADV), parainfluenza virus (PIV) types 1 to 3, and human metapneumovirus (HMPV). HBoV was detected with a real-time PCR method, and the other viruses were diagnosed using monoclonal antibodies in direct fluorescence assay. RESULTS: Viral etiology was proven in 225/295 (76.3%) of patients. The most commonly diagnosed virus was RSV (59.3%), followed by HBoV (23.1%), PIVs (4.4%), ADV (3.1%), and HMPV (1.4%). HBoV-infected children were older than RSV-infected children; likewise, detection rates of HBoV infection increased with age, while RSV infection rates decreased with age. In 51% of HBoV-positive samples an additional respiratory virus was also detected. There was no difference in HBoV DNA quantity between samples with single virus detection and those with multiple virus detection (p = 0.056), although samples positive only for HBoV showed higher cycle threshold values. There was no difference in HBoV DNA quantity in samples of different age groups (p > 0.05). CONCLUSIONS: Frequent detection of HBoV in small children with LRTI, even in combination with other viruses, highlights its role in the pathogenesis of respiratory disease.

Variability analysis and inter-genotype comparison of human respiratory syncytial virus small hydrophobic gene.

BACKGROUND: Small hydrophobic (SH) gene is one of the mostly diverse genomic regions of human respiratory syncytial virus (HRSV). Its coding region constitutes less than 50% of the complete gene length, enabling SH gene to be highly variable and the SH protein highly conserved. In standard HRSV molecular epidemiology studies, solely sequences of the second hypervariable region of the glycoprotein gene (HVR2) are analyzed. To what extent do the strains identical in HVR2 differ elsewhere in genomes is rarely investigated. Our goal was to investigate whether diversity and inter-genotype differences observed for HVR2 are also present in the SH gene. METHODS: We sequenced 198 clinical samples collected within a limited area and time frame. In this HRSV collection, rapid and significant changes in HVR2 occurred. RESULTS: Over 20% of strains from this pool (containing HRSV genotypes NA1, ON1, GA5, BA9 and BA10) would be incorrectly assumed to be identical to another strain if only the HVR2 region was analysed. The majority of differences found in SH gene were located in the 5' untranslated region (UTR). Seven indels were detected, one was genotype GA5 specific. An in-frame deletion of 9 nucleotides (coding for amino acids 49-51) was observed in one of group A strains. Fifteen different SH protein sequences were detected; 68% of strains possessed the consensus sequence and most of others differed from the consensus in only one amino acid (only 4 strains differed in 2 amino acids). The majority of differing amino acids in group A viruses had the same identity as the corresponding amino acids in group B strains. When analysis was restricted to strains with identical HVR2 nucleotide sequences and differing SH protein sequences, 75% of differences observed in the SH ectodomain were located within region coding for amino acids 49-51. CONCLUSIONS: Basing HRSV molecular epidemiology studies solely on HVR2 largely underestimates the complexity of circulating virus populations. In strain identification, broadening of the genomic target sequence to SH gene would provide a more comprehensive insight into viral pool versatility and its evolutionary processes.

Genetic diversity of human metapneumovirus in hospitalized children with acute respiratory infections in Croatia.

Human metapneumovirus (HMPV) is recognized as a global and frequent cause of acute respiratory tract infections among people of all ages. The objectives of this study were molecular epidemiology and evolutionary analysis of HMPV strains which produced moderate and severe acute respiratory tract infections in children in Croatia during four consecutive seasons (2011-2014). A total of 117 HMPV-positive samples collected from hospitalized pediatric patients presenting with acute respiratory tract infections and tested by direct immunofluorescence assay were first analyzed by amplifying a part of the F gene. Sixteen samples were further analyzed based on complete F, G, and SH gene sequences. HMPV genome was identified in 92 of 117 samples (78%) and the circulation of multiple lineages of HMPV was confirmed. In 2011, 2012, and 2014, subgroups A2 and B2 co-circulated, while B1 gained prevalence in 2013 and 2014. The study established the presence of a novel subcluster A2c in Croatia. This subcluster has only recently been detected in East and Southeast Asia. This study provides new insights into epidemiology and genetic diversity of HMPV in this part of Europe.

Genetic Variability and Sequence Relatedness of Matrix Protein in Viruses of the Families Paramyxoviridae and Pneumoviridae.

BACKGROUND: The families Paramyxoviridae and Pneumoviridae comprise a broad spectrum of viral pathogens that affect human health. The matrix (M) protein of these viruses has a central role in their life cycle. In line with this, molecular characteristics of the M proteins from variable viruses that circulated in Croatia were investigated. METHODS: Sequences of the M proteins of human parainfluenza virus (HPIV) 1-3 within the family Paramyxoviridae, human metapneumovirus (HMPV), and human respiratory syncytial virus from the family Pneumoviridae were obtained and analyzed. RESULTS: M proteins were very diverse among HPIVs, but highly conserved within each virus. More variability was seen in nucleotide sequences of M proteins from the Pneumoviridae family. An insertion of 8 nucleotides in the 3' untranslated region in 1 HMPV M gene sequence was discovered (HR347-12). As there are no samples with such an insertion in the database, this insertion is of interest and requires further research. CONCLUSION: While we have confirmed that M proteins were conserved among individual viruses, any changes that are observed should be given attention and further researched. Of special interest is inclusion of HPIV2 M proteins in this analysis, as these proteins have not been studied to the same extent as other paramyxoviruses.

Genetic diversity among human parainfluenza virus type 2 isolated in Croatia between 2011 and 2014.

The dynamics and evolution of the human parainfluenza virus type 2 (HPIV2) in Croatia, and also globally, are largely unknown. Most HPIV2 infections are treated symptomatically outside the hospital setting. Thus, the diagnosis is missing making it difficult to follow the genetic variation and evolution of the HPIV2. This study explores hospitalized HPIV2 cases in Croatia during 4-year period (2011-2014). Most cases in this period were reported in October or November (68.75%) and most of patients were under 2 years of age (81.25%). For molecular analyses, we used the F and HN gene sequences and showed that although both regions are equally suitable for phylogenetic analyses it would be advantageous to use regions longer than 2 kb for HPIV2 analyses of isolates which are spatially and temporally closely related. We show here that the dominant cluster in this area was cluster G3 while only one strain isolated in this period was positioned in the distant cluster G1a. Further monitoring of the HPIV2 will determine whether cluster G3 will remain dominant or it will be overruled by cluster G1a. This will be important for the surveillance of virus circulation in population and significance of the viral infection. J. Med. Virol. 88:1733-1741, 2016. © 2016 Wiley Periodicals, Inc.

Antimicrobial Sensitivity Profile of Chlamydia trachomatis isolates from Croatia in McCoy Cell Culture System and Comparison with the Literature.

BACKGROUND: Chlamydia trachomatis (C. trachomatis) is the most common bacterial agent of sexually transmitted infections around the world, but susceptibility testing of this pathogen is rarely pursued due to its intracellular niche. The principal aims of this research were to determine in vitro sensitivity profile of urogenital chlamydial strains isolated from Croatian patients and to compare obtained concentration values of different antimicrobial drugs mutually and with the literature. METHODS: Forty strains of C. trachomatis isolated during 2010-2012 at the National Reference Laboratory for Chlamydia and two reference strains were subjected to susceptibility testing in 96-well microtiter plates containing McCoy cell monolayers. Minimal inhibitory concentration (MIC) and minimal chlamydicidal concentration (MCC) were determined for azithromycin, doxycycline, and levofloxacin. Briefly, strains were inoculated on McCoy cells, followed by addition of serially diluted antimicrobial drugs. Upon incubation, growth of C. trachomatis was detected using fluorescein-conjugated antibody to the lipopolysaccharide genus antigen under the inverted fluorescent microscope. RESULTS: All chlamydial strains were susceptible to the antibiotics tested (MIC < 4 pg/mL), thus the pattern of homotypic or heterotypic resistance has not been found. MCC values were equal or 1-5 dilutions higher than MIC values. Statistically significant differences in the effectiveness of antimicrobial agents in vitro have been proven. Significant correlation has been found for MCCs in the case of two antimicrobial pairs: azithromycin and levofloxacin, and doxycycline and levofloxacin. Comparison of medians for different clinical samples did not reveal any significant difference. CONCLUSIONS: Although resistant strains have not been found in this study, several literature reports of unsuccessfully treated genitourinary infections caused by C. trachomatis require our alertness for possible discovery of resistant strains. Considering the overall antibiotic burden worldwide, pursuing this kind of research is crucial in order to detect possible decreased susceptibility (or even resistance) of chlamydial strains, despite the laborious and time-consuming methodology.

Prevalence of viral hepatitis in Croatian adult population undergoing routine check-up, 2010-2011.

Seroprevalence data on viral hepatitis in the general population vary widely. The aim of this study was to determine the prevalence of hepatitis A (HAV), hepatitis B (HBV) and hepatitis C (HCV) viruses in the general Croatian adult population undergoing routine check-ups. The seroprevalence of anti-HAV, anti-HBc and anti-HCV was 40.5%, 7.0% and 0.9%, respectively. HBsAg was found in 0.7% and anti-HBs antibodies in 24.4% of participants. Gender was not associated with HAV, HBV or HCV seropositivity. HAV and HBV seropositivity increased progressively with age (HAV from 11.7% to 90.4%, p < 0.001; HBV from 1.7% to 15.8%, p < 0.001). Participants from rural areas showed a significantly higher HBV seroprevalence rate than those from urban areas (10.7% vs. 6.1%, p = 0.007). Results of univariate and multiple logistic regression showed that older age was a significant predictor for both HAV and HBV seropositivity while rural place of residence was a significant predictor for HBV seropositivity.

[POLIOMYELITIS ERADICATION--ONE STEP TO ACHIEVE THE GOAL]. / ERADIKACIJA POLIOMIJELITISA--KORAK DO CILJA.

Poliomyelitis is a very old disease of humans, caused by poliovirus. With appearance of the epidemics in the 20th century, poliomyelitis became a global public health issue. In 1988, the World Health Organization started a campaign for global eradication of poliomyelitis and till now poliomyelitis cases have been reduced by more than 99%. In Croatia, the introduction of vaccination in 1961 resulted in dramatic reduction of paralytic disease. The European region, including Croatia was certified polio free in 2002. However, the final goal of the "polio-free world" has not yet been reached. To reinforce the campaign, the global polio eradication initiative has come up with the Polio Eradication & Endgame Strategic Plan 2013-2018 with detailed program how to resolve the main challenges: (a) continued transmission of wild polioviruses in endemic reservoirs; (b) reinfection of polio-free areas; and (c) outbreaks due to the circulating vaccine-derived polioviruses (cVDPV). Global oral polio vaccine cessation will follow, with the introduction of universal use of inactivated polio vaccine.

Detection of Macrolide and/or Fluoroquinolone Resistance Genes in Mycoplasma genitalium Strains Isolated from Men in the Northwest Region of Croatia in 2018-2023.

Mycoplasma genitalium (M. genitalium) poses a significant public health challenge due to its association with non-gonococcal urethritis (particularly in men) and antimicrobial resistance. However, despite the prevalence of M. genitalium infections and the rise in resistance rates, routine testing and surveillance remain limited. This is the first study from Croatia that aimed to assess the prevalence and trends of resistance in M. genitalium strains isolated from male individuals by detecting macrolide and fluoroquinolone resistance genes. The study also aimed to explore the factors associated with resistance and changes in resistance patterns over time. Urine samples collected from male individuals in the Zagreb County and northwest region of Croatia between 2018 and 2023 were tested for M. genitalium with the use of molecular methods. Positive samples were subjected to DNA extraction and multiplex tandem polymerase chain reaction (MT-PCR) targeting genetic mutations associated with macrolide (23S rRNA gene) and fluoroquinolone (parC gene) resistance. Of the 8073 urine samples tested from 6480 male individuals (and following the exclusion of repeated specimens), we found that the prevalence of M. genitalium infection was 2.2%. Macrolide resistance was observed in 60.4% of strains, while fluoroquinolone resistance was found in 19.2%. Co-resistance to both antibiotics was present in 18.2% of cases. A statistically significant increase in fluoroquinolone resistance was noted over the study period (p = 0.010), but this was not evident for azithromycin resistance (p = 0.165). There were no statistically significant differences in resistance patterns between age groups, whereas re-testing of patients revealed dynamic changes in resistance profiles over time. The high burden of macrolide resistance and increasing fluoroquinolone resistance underscore the urgent need for comprehensive resistance testing and surveillance programs. The implementation of resistance-guided treatment strategies, along with enhanced access to molecular diagnostics, is pivotal for effectively managing M. genitalium infections.

Full-genome characterization of a G8P[8] rotavirus that emerged among children with diarrhea in Croatia in 2006.

The whole genome of a G8P[8] rotavirus from the 2006 epidemic in Croatia was sequenced and showed a Wa-like genotype constellation. Its VP7 gene clustered with DS-1-like G8 African rotaviruses and a G8P[4] German strain. Remaining genes clustered with contemporary Belgian G1P[8] rotaviruses, suggesting reassortment between human G8 and G1P[8] rotaviruses in Croatia or other European countries.

[West nile virus infection: re-emergent disease in Croatia]. / Infekcija virusom zapadnog nila: re-emergentna bolest u hrvatskoj.

West Nile virus (WNV) is a small, enveloped, spherical virus that belongs to the family Flaviviridae, genus Flavivirus, Japanese encephalitis serocomplex. Natural reservoirs of WNV are birds, and the main vectors are mosquitoes of the genus Culex. There are seven genetic lineages of WNV. Lineages 1 and 2 are the most widely distributed (Africa, North and South America, Europe, Asia and Australia). About 80% of infections are asymptomatic. In 20% of patients nonspecific febrile disease occurs (West Nile fever). Less than 1% of infected persons will develop neuroinvasive WNV disease (meningitis, encephalitis, and poliomyelitis). In Croatia, antibodies to WNV were demonstrated in humans,bears and horses. In August-September 2012 clinical cases of human WNV neuroinvasive disease and asymptomatic acute infection in horses were reported for the first time in three eastern Croatian counties. The diagnosis was confirmed by serologic tests (enzyme immunoassay, IgG avidity, plaque-reduction neutralization test).

Rhinovirus-A True Respiratory Threat or a Common Inconvenience of Childhood?

A decade-long neglect of rhinovirus as an important agent of disease in humans was primarily due to the fact that they were seen as less virulent and capable of causing only mild respiratory infections such as common cold. However, with an advent of molecular diagnostic methods, an increasing number of reports placed them among the pathogens found in the lower respiratory tract and recognized them as important risk factors for asthma-related pathology in childhood. As the spread of rhinovirus was not severely affected by the implementation of social distancing and other measures during the coronavirus disease 2019 (COVID-19) pandemic, its putative pathogenic role has become even more evident in recent years. By concentrating on children as the most vulnerable group, in this narrative review we first present classification and main traits of rhinovirus, followed by epidemiology and clinical presentation, risk factors for severe forms of the disease, long-term complications and the pathogenesis of asthma, as well as a snapshot of treatment trials and studies. Recent evidence suggests that the rhinovirus is a significant contributor to respiratory illness in both high-risk and low-risk populations of children.

Comparison of MT-PCR with Quantitative PCR for Human Bocavirus in Respiratory Samples with Multiple Respiratory Viruses Detection.

Human bocavirus (HBoV) is an important respiratory pathogen, especially in children, but it is often found in co-detection with other respiratory viruses, which makes the diagnostic approach challenging. We compared multiplex PCR and quantitative PCR for HBoV with multiplex tandem PCR (MT-PCR) in 55 cases of co-detection of HBoV and other respiratory viruses. In addition, we investigated whether there is a connection between the severity of the disease, measured by the localization of the infection, and amount of virus detected in the respiratory secretions. No statistically significant difference was found, but children with large amount of HBoV and other respiratory virus had a longer stay in hospital.

Immunity to varicella-zoster virus in Croatian women of reproductive age targeted for serology testing.

OBJECTIVE: The aim of this study was to determine the immunity to varicella-zoster virus (VZV) in Croatian pregnant and non-pregnant women of reproductive age. METHODS: During 2007-2011, a total of 638 women aged 16-45 years were tested for the presence of VZV IgM and IgG antibodies using commercial enzyme-linked immunosorbent assay. Samples positive for IgG antibodies with positive or equivocal IgM antibodies were tested for IgG avidity. RESULTS: The overall IgG seroprevalence was 84.3 %. There was a significant increase in IgG seropositivity with age (OR = 1.04 for 1-year increase in age; 95 % CI 1.01-1.08). The lowest seroprevalence rate was reported in the 16-20 age groups (78.6 %), and the highest was in the 41-45 age groups (94.3 %). There was no significant difference in seroprevalence among women residing in urban and rural areas (83.6 vs. 87.0 %, OR 0.76, 95 % CI 0.43-1.34). CONCLUSIONS: The results of this study have shown that a high proportion of Croatian childbearing-aged women (15.7 %) who were referred to the laboratory for VZV serology testing are susceptible to VZV and, thus, at risk for contracting varicella during pregnancy. Serology testing of adolescent girls and adult women who do not have a documented history of varicella is encouraged with the aim of vaccinating seronegative girls and women against VZV before pregnancy. In addition, testing of pregnant women is advised to identify susceptible women and vaccinate them after delivery.

High prevalence of Bartonella henselae and Bartonella quintana antibodies in Croatian patients presenting with lymphadenopathy.

Between 2007 and 2010, a total of 268 Croatian patients with lymphadenopathy were tested for IgM/IgG antibodies to Bartonella (B.) henselae and B. quintana. Samples from 44.4% patients showed positive IgG antibodies: 35.8% to B. henselae, 6.7% to B. quintana and 1.9% to both Bartonella species. There was no difference in seropositivity between males and females (47.4% vs. 41.5%). Seroprevalence was high in all age groups (40.4-60.9%). Patients from urban and rural areas showed a similar seroprevalence rate (44.1% vs. 44.8%). Positive IgM antibodies were found in 28.3% patients varying from 17.5% and 37.5% among age groups. Most cases were reported from August to March.

The role of IgG avidity in diagnosis of cytomegalovirus infection in newborns and infants.

To evaluate the value of IgG avidity in diagnosis of congenital cytomegalovirus (CMV) infection in newborns and infants we collected serum samples from 40 infants under 12 months of age with suspected congenital CMV infection. Sera were tested for IgM, IgG and IgG avidity. For 25 of them, virus isolation and/or polymerase chain reaction (PCR) on urine specimens were performed. Thirteen (32.5%) patients showed the presence of CMV IgM antibodies, 3 (7.5%) had equivocal IgM result, and 24 (60.0%) patients had IgG antibodies only. Using IgG avidity, CMV infection (low avidity index-AI) was documented in 61.5% IgM positive and 54.2% IgM negative patients. Eight of nine (88.8%) IgM positive patients were positive either on virus isolation or PCR. In IgM negative patients, 46.6% urine cultures were positive for CMV and 66.6% were PCR positive. According to age, IgG avidity demonstrated acute/recent primary CMV infection in 58.8% patients younger than three months compared with 91.7% and 81.8% in 3-6 and 6-12 months old babies, respectively. In conclusion, IgG avidity is useful in diagnosis of CMV infection either in IgM positive or IgM negative children older than 3 months of age. In infants less than 3 months, transplacentally derived maternal IgG antibodies of high avidity influence on the IgG avidity result. In these children, CMV infection should be confirmed by direct virologic methods such as virus isolation or PCR.

[Virology diagnosis of re-emergent infections: dengue virus]. / Viroloska dijagnostika reemergentnih infekcija: virus dengue.

Dengue is acute viral disease transmitted to humans by Aedes mosquitoes (Ae. aegypti, Ae. albopictus). Dengue virus belongs to the family Flaviviridae, genus Flavivirus. There are four dengue virus serotypes (1-4) which are maintained endemically. The disease is endemic in tropical and subtropical areas between latitudes 35 degrees N and 35 degrees S. Infections may be asymptomatic or may produce a wide spectrum of diseases: non-specific febrile illness, dengue fever, dengue haemorrhagic fever or dengue shock syndrome. For the first time in Croatia, Ae. albopictus was registered in Zagreb in October 2004. In autumn 2005, additional records of Ae. albopictus presence were made in many places along the Adriatic coast. During 2007, two cases of imported dengue fever were reported in Croatia, after which similar imported cases appeared continually. In August 2010, the first autochthonous case of dengue fever was recorded on the peninsula Peljesac. Though Croatia is not endemic for dengue, the existence of a corresponding vector and a latent threat by imported dengue cases demand state-of-the-art and timely diagnostics. The most commonly used methods in laboratory diagnosis of dengue infections involve detection of viral RNA, antigen detection and serologic methods (detection of antibodies).