High Frequency Of Mixed Infections Research Articles

Longitudinal analysis on parasite diversity in honeybee colonies: new taxa, high frequency of mixed infections and seasonal patterns of variation

To evaluate the influence that parasites have on the losses of Apis mellifera it is essential to monitor their presence in the colonies over time. Here we analysed the occurrence of nosematids, trypanosomatids and neogregarines in five homogeneous colonies for up to 21 months until they collapsed. The study, which combined the use of several molecular markers with the application of a massive parallel sequencing technology, provided valuable insights into the epidemiology of these parasites: (I) it enabled the detection of parasite species rarely reported in honeybees (Nosema thomsoni, Crithidia bombi, Crithidia acanthocephali) and the identification of two novel taxa; (II) it revealed the existence of a high rate of co-infections (80% of the samples harboured more than one parasite species); (III) it uncovered an identical pattern of seasonal variation for nosematids and trypanosomatids, that was different from that of neogregarines; (IV) it showed that there were no significant differences in the fraction of positive samples, nor in the levels of species diversity, between interior and exterior bees; and (V) it unveiled that the variation in the number of parasite species was not directly linked with the failure of the colonies.

Modern tendency of prevention and treatment of infectious processes of the lower genital tract

Issue of the treatment of mixed genital infections and prevention of reproductive health disorders caused by them has not lost medical and social significance, which is associated with a high frequency of mixed infections, absence of pathognomonic clinical manifestations, and with a constantly significant frequency of sexually transmitted infections (chlamydia, genital herpes, trichomoniasis, etc.). It should be controlled and rationally limited antibiotics use in connection with a sharp increase in microorganisms’ resistance. At the same time proven antiseptics which are used to reduce the infection risk or to treat vaginal infections do not contribute to the formation of resistant pathogens. The purpose of this literature review was to analyze publications about modern antiseptic octenidine dihydrochloride for mucous membranes, skin and wounds and the prospects for it use in obstetric and gynecological practice. Octenidine dihydrochloride (octenidine) was synthesized as a multi-functional antiseptic for skin, mucous membranes and wounds. Today octenidine is an active antiseptic with a wide scope of use and is an alternative to chlorhexidine, povidone iodine, triclosan, etc. Octenidine is a cationic antiseptic of a new chemical group (derivatives of bispyridinamine), is a safe and effective antimicrobial agent with a high level and spectrum of antimicrobial activity. The antiseptic activity of octenidine is achieved within 30 seconds, it is chemically resistant, has proven low toxicity to humans and the environment and high clinical efficacy, does not cause the pathogen resistance, is approved for use from the second trimester in pregnancy and during breastfeeding. Octenidine use with or without combinations should be considered as an integral part of the standard therapy for various types of vaginitis and bacterial vaginosis. Octenidine can become a promising agent for therapeutic indications in gynecology in future, since it surpasses povidone iodine, polyhexanide and chlorhexidine in the efficiency of microorganisms’ eradication from the mucous membranes.

Detection of different enteric viruses in children with diarrheal disease: evidence of the high frequency of mixed infections.

Enteric viruses play a major role in causing diarrhea in children. Early identification of the causative pathogen is still a challenge in the clinical laboratory. A multiplex PCR assay is a useful tool to screen a large number of clinical samples especially in an outbreak situation. In this study, a multiplex reverse transcription (RT)-PCR assay was developed to detect nine enteric viruses such as group A rotavirus, norovirus GGII, sapovirus, adenovirus, astrovirus, aichivirus, parechovirus, bocavirus and enterovirus in clinical samples of diarrheal cases. Stool samples (n=185) collected from infants and children with acute gastroenteritis cases in Pune, western India were analysed for nine different enteric viruses by currently developed multiplex RT- PCR. Predominance of group A rotavirus (76%) followed by enterovirus (11.5%), astrovirus (4.5%), adenovirus (2.7%) and norovirus GII (1.6%) was observed. A total of 44.8 % (82/185) samples analysed by this method showed high frequency of mixed infections. These results highlighted high prevalence and diversity of different enteric viruses in children. The multiplex PCR showed good concordance with monoplex RT-PCR for detection of these enteric viruses in clinical samples. This is the first report on the development of a multiplex RT-PCR assay for detection of multiple enteric viruses in diarrheal diseases from India.

Cryptosporidium in fish: alternative sequencing approaches and analyses at multiple loci to resolve mixed infections

Currently, the systematics, biology and epidemiology of piscine Cryptosporidium species are poorly understood. Here, we compared Sanger ‒ and next-generation ‒ sequencing (NGS), of piscine Cryptosporidium, at the 18S rRNA and actin genes. The hosts comprised 11 ornamental fish species, spanning four orders and eight families. The objectives were: to (i) confirm the rich genetic diversity of the parasite and the high frequency of mixed infections; and (ii) explore the potential of NGS in the presence of complex genetic mixtures. By Sanger sequencing, four main genotypes were obtained at the actin locus, while for the 18S locus, seven genotypes were identified. At both loci, NGS revealed frequent mixed infections, consisting of one highly dominant variant plus substantially rarer genotypes. Both sequencing methods detected novel Cryptosporidium genotypes at both loci, including a novel and highly abundant actin genotype that was identified by both Sanger sequencing and NGS. Importantly, this genotype accounted for 68·9% of all NGS reads from all samples (249 585/362 372). The present study confirms that aquarium fish can harbour a large and unexplored Cryptosporidium genetic diversity. Although commonly used in molecular parasitology studies, nested PCR prevents quantitative comparisons and thwarts the advantages of NGS, when this latter approach is used to investigate multiple infections.

CHILDREN ACUTE ENTERIC INFECTIONS IN PAEDIATRICIAN PRACTICE: POSSIBILITIES OF DIAGNOSTICS AND THERAPY

Acute Enteric Infections (AEI) occupy one of the leading places in structure of infectious pathology at children's age. A variety of etiological agents (bacteria, viruses and protozoa) causing infectious diarrhoea, the high frequency of mixed infections, frequent failures and uneven course prove the necessity of search of ways for optimization of diagnostic and therapeutic approaches according to modern scientific data. The principles of clinical and laboratory diagnostics of AEI are considered in the article. Criteria of the assessment of a disease severity, predictive criteria of development of the life-threatening states connected with the exicosis are presented. The principles of AEI treatment are presented from the modern positions, the necessity of an integrated approach and staging in therapy with the personified choice of preparations considering weight, phase and clinical form of a disease, age of a child and a macroorganism condition by the time of the disease beginning are introduced. The necessity of a strictly differentiated approach to prescription of antibiotics is emphasized. The data on expediency of inclusion of probiotics to starting AEI therapy of virus aetiology are separately presented taking into account strain-specific efficiency that provides the reliable reduction of degree of intensity and duration of the main symptoms of a disease, and also has beneficial impact on a condition of microflora of a gastrointestinal path.

Multilocus genotyping of Giardia duodenalis in lambs from Spain reveals a high heterogeneity

Fecal specimens from 120 lambs in Valencia (Spain) were analyzed for Giardia duodenalis by IFA and nested-PCR using the beta giardin (bg), glutamate dehydrogenase (gdh), triose phosphate isomerase (tpi) and small subunit ribosomal RNA (ssurRNA) genes. The highest prevalence was obtained using the ssurRNA gene (89.2%), whereas values from other techniques ranged from 64.1% to 69.2%. Sequences of the ssurRNA showed a high proportion of assemblage A or mixed assemblage A/E samples (55.1% and 25.2%, respectively). When the other 3 loci were analyzed, between 6.5% and 15.4% were found to be assemblage A or A/E, respectively. Nested PCR for the tpi gene was the most variable of the targets employed. Twelve new sequences of gdh and tpi for G. duodenalis from sheep were found. Multilocus genotyping resulted in 63 patterns from the 71 samples sequenced at the four loci. This high variability among isolates possibly reflects the high frequency of mixed infections.

Biologic and genetic characteristics of Toxoplasma gondii isolates in free-range chickens from Nicaragua, Central America

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 98 free-range chickens ( Gallus domesticus) from Nicragua was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 84 (85.7%) of 98 chickens with titers of 1:5 in 10, 1:10 in eight, 1:20 in seven, 1:40 in nine, 1:80 in 11, 1:160 in one, 1:200 in 27, 1:400 in six, 1:800 four, and 1:3200 in one bird. Hearts and brains of 32 chickens with titers of 1:10 or less were pooled and fed to three T. gondii-free cats. Hearts and brains of 66 chickens with titers of 1:20 or higher were bioassayed in mice. Feces of cats were examined for oocysts. The cat fed tissues from eight chickens with titers of 1:10 shed T. gondii oocysts. The two cats fed tissues of 24 chickens with titers of 1:5 or less did not shed oocysts. T. gondii was isolated by bioassay in mice from 47 chickens with MAT titers of 1:20 or higher. All infected mice from six isolates died of toxoplasmosis. Overall, 41 of 170 (24.1%) mice that became infected after inoculation with chicken tissues died of toxoplasmosis. Genotyping of these 48 isolates (47 from mice and 1 from pooled tissues) using polymorphisms at the loci SAG1, SAG2, SAG3, BTUB and GRA6 revealed eight genotypes. Six isolates had Type I alleles, three isolate had Type II alleles and six isolates had Type III alleles at all loci. Four isolates had mixed infections. Two isolates have a unique allele at SAG1 locus and combination of I and III alleles at other loci. The rest 27 isolates contained the combination of Type I and III alleles and were divided into four genotypes. More than one genotypes were often isolated in chickens from the same household, indicating multiple genotypes were circulating in the same environment. This may explain the high frequency of mixed infections observed. High rate of mixed infection in intermediate hosts such as chickens may facilitate genetic exchange between different parasite lineages in definitive feline hosts. This is the first report of genetic characterization of T. gondii isolates from Nicragua, Central America.

Community-acquired pathogens associated with prolonged coughing in children: a prospective cohort study

A 2‐year prospective study was performed of children with prolonged coughing to investigate the frequency of different respiratory pathogens, the rate of mixed infections, and possible differences in severity of disease between single and mixed infections. Sera from 135 children (136 episodes of prolonged coughing lasting 1–6 weeks) were tested for antibodies to different viruses and bacteria. Swabs were taken for culture and PCR to detect different viral and bacterial pathogens. One or more pathogens were found in 91 (67%) patients. One infectious agent was found in 49 (36%) patients, two agents in 35 (26%) patients, and more than two agents in seven (5%) patients. The most frequent pathogens encountered were rhinovirus (n = 43; 32%), Bordetella pertussis (n = 23; 17%) and respiratory syncytial virus (n = 15; 11%). The most frequent mixed infection was B. pertussis and rhinovirus (n = 14; 10%). No significant differences in clinical symptoms were observed between patients with or without pathogens; however, patients with mixed infections were significantly older. There was a strong seasonal influence on the number of infections, but not on the number of mixed infections. In children with prolonged coughing, there was a high frequency of mixed infections regardless of the season. However, mixed infection was not associated with increased disease severity. No clinical symptoms were found that allowed discrimination between specific pathogens.

Characterisation of rotavirus strains among hospitalised and non-hospitalised children in Guinea-Bissau, 2002

In a previous community-based cohort study in Guinea-Bissau from 1996 to 1998, characterisation of rotavirus strains showed a high frequency of less common genotypes such as G8 and G9 and a high proportion of mixed infections. In the present study, we examined the prevalence of rotavirus genotypes among 81 hospitalised and 23 non-hospitalised Guinean children with rotavirus associated diarrhoea during the 2002 seasonal rotavirus outbreak. G- and P-types were determined in a two-step procedure using reverse transcription followed by a standard multiplex PCR. The multiplex PCR for G-types was furthermore supplemented with a single locus PCR including the MW8 primer for the G8-genotype. The dual infection G2/P[4]P[6] (24%) appeared to be the most frequent cause of rotavirus infections followed by G2P[4] (19%), G2P[6] (16%) and G8P[6] (13%). Overall 38% of the infections were mixed and 18% of the samples had the genotype G8. However, by subjecting all samples and not only the strains, which according to the standard multiplex PCR procedure were non-typeable, to a single locus G8-PCR, we found that the genotype G8 appeared in 62% of the infections, either as a single G-strain or in combination with other G-types, especially G2. Including these results, more than 63% of infections emerged as mixed. Neither genotype (including the presence of G8) nor the presence of mixed infections, seem to influence the severity of the rotavirus infection. We found a high frequency of mixed infections especially due to G8-genotypes, which might have implications for development of rotavirus vaccine candidates for use in Africa. Our results do not suggest that a single genotype is associated with severity, but the present study is based on a modest number of samples and results should be interpreted with caution.

Characterization of Rotavirus Strains in a Danish Population: High Frequency of Mixed Infections and Diversity within the VP4 Gene of P[8] Strains

We characterized the G and P types from 162 rotavirus-positive stool specimens collected from 162 persons in Denmark (134 children and 28 adults) with acute diarrhea in 1998, 2000, and 2002. Samples were obtained during outpatient consultations (73%) and from hospitalized patients (27%). Although more than 20 different G-P combinations were identified, only 52% represented the globally most common types G1P[8], G2P[4], and G4P[8]. The G9 genotype, which is emerging worldwide, was identified in 12% of all samples. Twenty-one percent of the samples were of mixed genotypic origin, which is the highest frequency reported in any European population. The standard reverse transcription-PCR methods initially failed to identify a considerable fraction of the rotavirus P strains due to mutations at the VP4 primer-binding sites of P[8] strains. The application of a degenerate P[8] primer resulted in typing of most VP4 strains. There was considerable year-to-year variation among the circulating G-P types, and whereas G1P[8] was predominant in 1998 (42% of samples) and 2002 (26%), G2P[4] was the strain that was most frequently detected in 2000 (26% of samples). Our findings might implicate challenges for rotavirus vaccine implementation in a European population and underscore the importance of extensive strain surveillance prior to, during, and after introduction of any vaccine candidate.

Characterization of incompletely typed rotavirus strains from Guinea-Bissau: identification of G8 and G9 types and a high frequency of mixed infections

Among 167 rotavirus specimens collected from young children in a suburban area of Bissau, Guinea-Bissau, from 1996 to 1998, most identifiable strains belonged to the uncommon P[6], G2 type and approximately 50% remained incompletely typed. In the present study, 76 such strains were further characterized. Due to interprimer interaction during the standard multiplex PCR approach, modifications of this procedure were implemented. The modified analyses revealed a high frequency of G2, G8, and G9 genotypes, often combined with P[4] and/or P[6]. The Guinean G8 and G9 strains were 97 and 98%, respectively, identical to other African G8 and G9 strains. Multiple G and/or P types were identified at a high frequency (59%), including two previously undescribed mixed infections, P[4]P[6], G2G8 and P[4]P[6], G2G9. These mixed infections most likely represent naturally occurring reassortance of rotavirus strains. Detection of such strains among the previously incompletely typed strains indicates a potential underestimation of mixed infections, if only a standard multiplex PCR procedure is followed. Furthermore cross-priming of the G3 primer with the G8 primer binding site and silent mutations at the P[4] and P[6] primer binding sites were detected. These findings highlight the need for regular evaluation of the multiplex primer PCR method and typing primers. The high frequency of uncommon as well as reassortant rotavirus strains in countries where rotavirus is an important cause of child mortality underscores the need for extensive strain surveillance as a basis to develop appropriate rotavirus vaccine candidates.

HELMINTHS OF MICROTINAE IN WESTERN MONTANA

Seventeen species of helminths were found in 134 voles of 5 species (Phenacomys intermedius, Clethrionomys gapperi, Microtus longicaudus, Microtus montanus, Microtus pennsylvanicus) collected in 1964 and 1965 in western Montana. Ten new records for North America and 26 new records for Montana were recorded. Seasonal patterns of infection were noted in Quinqueserialis quinqueserialis and Paranoplocephala infrequens. The taxonomy of the nematode Heligmosomum dubius (Baylis, 1926) Tenora, 1958 was discussed. The first record of Aspiculuris tetraptera in. microitne rodents and the second record of Pelodera sp. in the orbits of North American rodents were reported. A high frequency of mixed infections of the digestive tract was found, usually accompanied by a pronounced stratification of the helminths within the tract.