Socio-demographic and psycho-social determinants of HIV late presentation in Germany - results from the FindHIV study

Delayed HIV diagnosis at advanced stages of disease remains common (33%-64%). This analysis of the multi-center FindHIV study including newly diagnosed HIV-infected adults in Germany, focused on the potential role of socio-demographic and psychological factors on late diagnosis (formerly "late presentation", AIDS diagnosis or CD4 cells <350/µL). These data were collected from patient profiles, physician-patient interviews and questionnaires. Participating centers (n = 40) represented the diverse health care settings in HIV care and geographic regions. Of 706 newly diagnosed adults (92% male, median age 39 years) between 2019 and 2020, 55% (388/706) were diagnosed late with a median CD4 cell count of 147/µL; 20% (142/706) presented with AIDS. From the physicians' perspective, earlier diagnosis would have been possible in 45% of participants (late versus non-late presentation 58% versus 29%). The most common physician-perceived reason was an underestimated risk for HIV infection by the patient (37%). In multivariable logistic regression analysis, older age, sexual contacts with both sexes as possible route of HIV transmission, being married, and a poor level of knowledge about HIV treatment were found to be associated with a significantly elevated risk for late presentation. Education, employment status, sexual relations, migration background and personality traits were not.Trial registration: German Clinical Trials Register (DRKS00016351).

Clinical characteristics of monkeypox virus infections among men with and without HIV: A large outbreak cohort in Germany

BACKGROUND

Since May 2022, increasing numbers of monkeypox virus (MPXV) infections have been reported from across Europe and North America. Studies, mainly from Africa, have suggested a higher risk for severe MPXV cases in people living with HIV.

METHODS

This was a retrospective study of all confirmed MPXV infections observed in the participating centres since 19 May 2022. We conducted a chart review to evaluate clinical characteristics, comorbidities, and coinfections, including HIV, viral hepatitis, and sexually transmitted infections (STIs).

RESULTS

By 30 June 2022, a total of 546 MPXV infections were reported from 42 German centres. All patients were men who have sex with men (MSM), of whom 256 (46.9%) were living with HIV, mostly with a preserved immune system and with viral suppression. In total, 232 (42.5%) MSM were also taking HIV pre-exposure prophylaxis (PrEP) and 58 (10.6%) MSM had no known HIV infection or PrEP use. The median age was 39 years (range 20-67), and comorbidities were rare. However, 52.4% and 29.4% of all patients had been diagnosed with at least one STI within the last 6 months or within the last 4 weeks, respectively. The most frequent localizations of MPXV infection were genital (49.9%) and anal (47.9%), whereas fever (53.2%) and lymphadenopathy (42.6%) were the most frequent general symptoms. The hospitalization rate was low (4.0%), and no fatal course was observed. The clinical picture showed no apparent differences between MSM with or without HIV.

CONCLUSIONS

In this preliminary cohort analysis from a current large outbreak among MSM in Germany, the clinical picture of MPXV infection did not differ between MSM with and without HIV infection. Severe courses were rare and hospitalization rates were low. However, most patients were relatively healthy, and only a few people living with HIV were viremic or severely immunosuppressed.

Host KIR/HLA-C Genotypes Determine HIV-Mediated Changes of the NK Cell Repertoire and Are Associated With Vpu Sequence Variations Impacting Downmodulation of HLA-C

NK cells play a pivotal role in viral immunity, utilizing a large array of activating and inhibitory receptors to identify and eliminate virus-infected cells. Killer-cell immunoglobulin-like receptors (KIRs) represent a highly polymorphic receptor family, regulating NK cell activity and determining the ability to recognize target cells. Human leukocyte antigen (HLA) class I molecules serve as the primary ligand for KIRs. Herein, HLA-C stands out as being the dominant ligand for the majority of KIRs. Accumulating evidence indicated that interactions between HLA-C and its inhibitory KIR2DL receptors (KIR2DL1/L2/L3) can drive HIV-1-mediated immune evasion and thus may contribute to the intrinsic control of HIV-1 infection. Of particular interest in this context is the recent observation that HIV-1 is able to adapt to host HLA-C genotypes through Vpu-mediated downmodulation of HLA-C. However, our understanding of the complex interplay between KIR/HLA immunogenetics, NK cell-mediated immune pressure and HIV-1 immune escape is still limited. Therefore, we investigated the impact of specific KIR/HLA-C combinations on the NK cell receptor repertoire and HIV-1 Vpu protein sequence variations of 122 viremic, untreated HIV-1⁺ individuals. Compared to 60 HIV-1^- controls, HIV-1 infection was associated with significant changes within the NK cell receptor repertoire, including reduced percentages of NK cells expressing NKG2A, CD8, and KIR2DS4. In contrast, the NKG2C⁺ and KIR3DL2⁺ NK cell sub-populations from HIV-1⁺ individuals was enlarged compared to HIV-1^- controls. Stratification along KIR/HLA-C genotypes revealed a genotype-dependent expansion of KIR2DL1⁺ NK cells that was ultimately associated with increased binding affinities between KIR2DL1 and HLA-C allotypes. Lastly, our data hinted to a preferential selection of Vpu sequence variants that were associated with HLA-C downmodulation in individuals with high KIR2DL/HLA-C binding affinities. Altogether, our study provides evidence that HIV-1-associated changes in the KIR repertoire of NK cells are to some extent predetermined by host KIR2DL/HLA-C genotypes. Furthermore, analysis of Vpu sequence polymorphisms indicates that differential KIR2DL/HLA-C binding affinities may serve as an additional mechanism how host genetics impact immune evasion by HIV-1.

Functional Hypogonadism and Testosterone Deficiency in Aging Males With and Without HIV-infection

INTRODUCTION

HIV infection has become a chronic, well-treatable disease and the focus of caretakers has shifted to diagnosis and treatment of comorbidities. Hypogonadism in elderly men with HIV might be of particular relevance, however, little is known about its epidemiology in contrast to non-infected peers and men with other chronic medical conditions, such as type 2 diabetes. This study aimed at comparing the prevalence of testosterone deficiency and functional hypogonadism in men ≥ 50 years in these three groups.

PATIENTS AND METHODS

Multi-center, cross-sectional substudy of the German-wide 50/2010 study, including men aged 50 years or older with HIV-infection, type 2 diabetes, and controls.

RESULTS

Altogether, 322 men were included (mean age: 62 years (SD±7.9)). The prevalence of testosterone deficiency in men living with HIV, type 2 diabetes, and controls was 34.5, 44.9, and 35.0%, respectively; the prevalence of functional hypogonadism was 7.7, 14.3 and 3.5%, respectively. Single-factor ANOVA demonstrated significant differences between the groups for total testosterone (p<0.001), SHBG (p<0.001), as well as for free testosterone concentrations (p=0.006). Comorbidities were, however, most important single factor in multi-factor analysis.

DISCUSSION

Despite a comparable prevalence of testosterone deficiency, functional hypogonadism was more frequent in men living with HIV when compared to non-infected controls. This was the result of a higher burden of symptoms that might, however, also be secondary to other conditions. Number of comorbidities was a more important factor than belonging to one of the groups.

1269. Cohort Profile: The Translational Platform HIV (TP-HIV), a Multicenter Cohort Project in Germany

Background

While Germany has a long tradition in HIV research with many well-established regional cohorts, there was a lack of collaborative efforts toward harmonized data collection and biobanking, both key strategies for efficient translational research projects. Key challenges are heterogeneity of data systems and privacy concepts, of existing study and data collection protocols, and sample collection, storage, and sharing.

Methods

In 2013, we established the Translational Platform HIV (TP-HIV) with support of the German Centre for Infection Research (DZIF) as a collaboration between university hospitals and specialized HIV care centers throughout Germany. After assessing the individual needs of all partner sites, we have taken comprehensive action to create a common platform for collaboration in all research stages. We developed protocols, rules of operation, biobanking strategies, and privacy concepts for all collaborating partner sites. Patients infected with HIV (PLWH) who sign the informed consent for the TP-HIV are pro- and retrospectively included in the cohort.

Results

To date, the TP-HIV infrastructure is implemented at 27 member sites from 11 cities, potentially extending to more than 20,000 patients currently treated for HIV across Germany. Facing the special needs in the German research environment, the TP-HIV established a unique data- and biomaterial collection allowing expedited translational research and reduce project overheads, regulatory burden, and data security regulations for investigators. By active surveillance, rapid access to individual patient groups such as patients with acute HIV infection, TP-HIV is an ideal platform for early phase clinical trials with new drug candidates. Researchers with clinical, biological, epidemiological, and statistical expertise have been brought together within the TP-HIV, which enables an effective translational chain from bench to bedside and back. New collaborations have been established with currently 23 active study protocols.

Conclusion

The TP-HIV has demonstrated to be a powerful tool for generating and testing research hypotheses in PLWH. In the future, we will work to further expand our network and address the pressing needs in the German research environment.

Disclosures

All authors: No reported disclosures.

Positive reinforcement targeting abstinence in substance misuse (PRAISe): Study protocol for a Cluster RCT & process evaluation of contingency management

There are approximately 256,000 heroin and other opiate users in England of whom 155,000 are in treatment for heroin (or opiate) addiction. The majority of people in treatment receive opiate substitution treatment (OST) (methadone and buprenorphine). However, OST suffers from high attrition and persistent heroin use even whilst in treatment. Contingency management (CM) is a psychological intervention based on the principles of operant conditioning. It is delivered as an adjunct to existing evidence based treatments to amplify patient benefit and involves the systematic application of positive reinforcement (financial or material incentives) to promote behaviours consistent with treatment goals. With an international evidence base for CM, NICE recommended that CM be implemented in UK drug treatment settings alongside OST to target attendance and the reduction of illicit drug use. While there was a growing evidence base for CM, there had been no examination of its delivery in UK NHS addiction services. The PRAISe trial evaluates the feasibility, acceptability, clinical and cost effectiveness of CM in UK addiction services. It is a cluster randomised controlled effectiveness trial of CM (praise and financial incentives) targeted at either abstinence from opiates or attendance at treatment sessions versus no CM among individuals receiving OST. The trial includes an economic evaluation which explores the relative costs and cost effectiveness of the two CM intervention strategies compared to TAU and an embedded process evaluation to identify contextual factors and causal mechanisms associated with variations in outcome. This study will inform UK drug treatment policy and practice. Trial registration ISRCTN 01591254.

Treatment Intensification in HIV-Infected Patients Is Associated With Reduced Frequencies of Regulatory T Cells

In untreated HIV infection, the efficacy of T cell responses decreases over the disease course, resulting in disease progression. The reasons for this development are not completely understood. However, immunosuppressive cells are supposedly crucially involved. Treatment strategies to avoid the induction of these cells preserve immune functions and are therefore the object of intense research efforts. In this study, we assessed the effect of treatment intensification [=5-drug antiretroviral therapy (ART)] on the development of suppressive cell subsets. The New Era (NE) study recruited patients with primary HIV infection (PHI) or chronically HIV-infected patients with conventional ART (CHI) and applied an intensified 5-drug regimen containing maraviroc and raltegravir for several years. We compared the frequencies of the immune suppressive cells, namely, the myeloid-derived suppressor cells (MDSCs), regulatory B cells (Bregs), and regulatory T cells (Tregs), of the treatment intensification patients to the control groups, especially to the patients with conventional 3-drug ART, and analyzed the Gag/Nef-specific CD8 T cell responses. There were no differences between PHI and CHI in the NE population (p > 0.11) for any of the studied cell types. Polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC), monocytic myeloid-derived suppressor cell (M-MDSC), and the Breg frequencies were comparable to those of patients with a 3-drug ART. However, the Treg levels were significantly lower in the NE patients than those in 3ART-treated individuals and other control groups (p ≤ 0.0033). The Gag/Nef-specific CD8 T cell response was broader (p = 0.0134) with a higher magnitude (p = 0.026) in the NE population than that in the patients with conventional ART. However, we did not find a correlation between the frequency of the immune suppressive cells and the interferon-gamma⁺ CD8 T cell response. In the treatment intensification subjects, the frequencies of the immune suppressive cells were comparable or lower than those of the conventional ART-treated subjects, with surprisingly broad HIV-specific CD8 T cell responses, suggesting a preservation of immune function with the applied treatment regimen. Interestingly, these effects were seen in both treatment intensification subpopulations and were not attributed to the start of treatment in primary infection.

[Cervical giant tumor in a 56-year-old female patient]

We report the case of a 56-year-old female patient with a giant tumor on the left side of the neck, which appeared to be localised outside the large salivary glands. Due to the extensive vascularisation seen on MRI, digital subtraction angiography was performed. To reduce intraoperative bleeding, the vasculature was embolized. The tumor was resected together with the submandibular gland, since a connection between gland and tumor could not be excluded intraoperatively. Histology showed a pleomorphic adenoma with an intact capsule and no indication of malignancy. Pleomorphic adenomas are typical tumors of the salivary glands; however, they can also occur outside the gland. The tumor and its pseudocapsule must be fully resected to prevent recurrence.

[Intoxication with cyclopentolate eye drops]

We report on an accidental intoxication with cyclopentolate eye drops. A 90-year-old patient became confused and was admitted to the emergency department. His symptoms consisted of disorientation, ataxia, and psychomotor agitation. Similar cases have been described in the literature. With this case report we would like to draw attention to this little known differential diagnosis when confronted with confused patients.

Scanning for telomeric deletions and duplications and uniparental disomy using genetic markers in 120 children with malformations

We screened 120 children with sporadic multiple congenital anomalies and either growth or mental retardation for uniparental disomy (UPD) or subtelomeric deletions. The screening used short tandem repeat polymorphisms (STRP) from the subtelomeric regions of 41 chromosome arms. Uninformative marker results were reanalyzed by using the next available marker on that chromosome arm. In total, approximately 25,000 genotypes were generated and analyzed for this study. Subtelomeric deletions of 1 Mb in size were excluded for 27 of 40 chromosome arms. Among the 120 subjects none was found to have UPD, but five subjects (4%, 95% confidence interval 1-9%) were found to have a deletion or duplication of one or more chromosome arms. We conclude that UPD is not a frequent cause of undiagnosed multiple congenital anomaly syndrome. In addition, we determined that 9p and 7q harbor chromosome length variations in the normal population. We conclude that subtelomeric marker analysis is effective for the detection of subtelomeric duplications and deletions, although it is labor intensive. Given a detection rate that is similar to prior studies and the large workload imposed by STRPs, we conclude that STRPs are an effective, but impractical, approach to the determination of segmental aneusomy given current technology.

Imprinting status of 11p15 genes in Beckwith-Wiedemann syndrome patients with CDKN1C mutations

Beckwith-Wiedemann syndrome (BWS) is an imprinting disorder characterized by somatic overgrowth, congenital malformations, and predisposition to childhood tumors. Aberrant expression of multiple imprinted genes, including H19, IGF2, KCNQ1OT1, and CDKN1C, has been observed in BWS patients. It has been estimated that mutations in CDKN1C occur in 12-17% of BWS patients. We have screened 10 autosomal dominant pedigrees and 65 sporadic BWS cases by PCR/heteroduplex analysis and DNA sequencing and have identified four mutations, two of which were associated with biallelic IGF2 expression and normal H19 and KCNQ1OT1 imprinting. One patient demonstrated phenotypic expression of paternally transmitted mutation in this maternally expressed gene, a second proband is the child of one of a pair of monozygotic twin females who carry the mutation de novo, and a third patient exhibited unusual skeletal changes more commonly found in other overgrowth syndromes. When considered with other studies published to date, this work reveals the frequency of CDKN1C mutations in BWS to be only 4.9%. This is the first report of an analysis of the imprinting status of genes in the 11p15 region where CDKN1C mutations were associated with loss of IGF2 imprinting and maintenance of H19 and KCNQ1OT1 imprinting.

Design and validation of an ELISA for equine infectious anemia (EIA) diagnosis using synthetic peptides

Three peptides derived from the equine infectious anemia virus (EIAV) surface proteins were synthesized to design and validate an ELISA for EIA diagnosis. Peptides identified as gp90-I and gp90-II correspond to the N- and C-terminal part of the surface glycoprotein gp90. Peptide gp45-1 overlaps the immunodominant epitope CIERTHVFC of the transmembrane glycoprotein gp45, and includes a hydrophilic chain close to the N-terminal end of this nonapeptide loop. Serum samples from 140 naturally infected horses with EIAV and a panel of 167 non-immune equine sera obtained from non-infected animals were used. Differences in reactivity between positive and negative serum samples were clearly distinguished. Samples considered weak positive to the agar gel immunodiffusion (AGID) test were "true" positive in the ELISA. These results are consistent with the improved sensitivity of the ELISA in comparison with the AGID test. The cyclic peptide that mimics the immunodominant sequence of gp45 showed excellent reactivity, thus suggesting that its functional activity depends significantly on its conformation, since very low reactivity was observed in the linear form of the peptide. The detectability indices of positive and negative sera reached 98% when gp90-II and gp45-I synthetic peptides were used in the same assay, illustrating the high specificity and sensitivity of the assay. Our study represents a first approach for the design of a diagnostic kit, which would allow the rapid analysis of a large numbers of serum samples from horses, and could be applied in endemic areas with different prevalence of infection.

Low dose cabergoline induced interstitial pneumonitis

Certain dopaminergic anti-Parkinson drugs (ergolines) have repeatedly been identified as a cause of pleuropulmonary disease with a focus on serosal cell damage. Recently, a pathogenetic link between ergolines and prior asbestos exposure was suggested, as regards the development of pleural pathology. This report describes a patient with idiopathic Parkinson's disease, who was on a multiple drug regimen including low dose cabergoline. The patient developed a febrile illness with widespread bilateral lung infiltrations nonresponsive to beta-lactam and macrolide antibiotics. Bronchoalveolar lavage and transbronchial lung biopsy showed a "hypersensitivity-like" interstitial lung disease, which cleared almost completely within 2 months after simple drug withdrawal. Circumstantial evidence suggests a so far undescribed adverse lung reaction to cabergoline, devoid of the more usual pleural changes.

Familial ovarian germ cell cancer: report and review

Ovarian germ cell cancers are rare malignancies accounting for less than 5% of all ovarian cancers. We present a family in which three closely related women were diagnosed with ovarian germ cell malignancies. This family's cancer history prompted a family history investigation of women treated for ovarian germ cell malignancies in the Gynecologic-Oncology Clinic at the University of Wisconsin. One of the eight patients whose family histories were reviewed had an uncle who had been diagnosed with testicular germ cell cancer. A review found six other previously reported families in which more than one relative had been diagnosed with a malignant ovarian germ cell tumor. Additionally, several cases of families with both males and females diagnosed with germ cell cancers have been documented. The low incidence of ovarian germ cell cancers suggests that multiple occurrences in the same family may not be due to chance. Rather, it is possible that a gene conferring susceptibility to ovarian germ cell cancers, and possibly to germ cell tumors in males as well, is present in at least some of these families.

[Chylothorax as a complication of sarcoidosis]

This case report features a male patient of 45 years of age presenting with a right sided moderately compressive pleural effusion, that was clearly identified as chylothorax on thoracocentesis. Sarcoidosis with systemic involvement had already been diagnosed in 1995 by a parotid gland biopsy. Thoracoscopy revealed multiple discrete nodules parietally besides a number of more extensive yellowish lesions resembling malignant lymphoma. However visualization of a thoracic duct leakage was not possible. Histologically the biopsies taken represented exclusively non-caseating sarcoidosistype granulomas. Complete and permanent remission of the chylothorax was achieved within only ten days following talcum pleurodesis, alimentary measures and induction of systemic steroid therapy. The etiological classification of this extremely rare complication appears very clear. Pathogenetic and differential therapeutic aspects are discussed against the background of a review of the literature.

Comparison of radiographer/radiologist double film reading with single reading in breast cancer screening

OBJECTIVES - To assess the efficacy of dual film reading in screening mammography with a suitably trained radiographer as the second reader and to determine a suitable decision model for radiographer/radiologist double reading. SETTING - Three breast screening centres in South Thames (West) region. METHODS - Seven radiographers with prior film reading training double read 17 202 screening mammograms with a radiologist. Screening performance of radiographers and radiologists was assessed taking into account interval cancers. The efficacy of radiographer/radiologist double reading was assessed in terms of changes in sensitivity and specificity compared with radiologist single reading. RESULTS - Radiographers yielded equivalent sensitivity but lower specificity than radiologist film readers. The effect of double reading between radiographer/radiologist pairs was an increase in sensitivity of 6-4%, which was achieved at the cost of a 0-6% decrease in specificity. This was reached by a decision system involving radiologists' review of radiographer queries and recall classifications. If all radiographer queries were recalled a large increase in sensitivity would be counterbalanced by an equally large decrease in specificity. CONCLUSIONS - Radiographer/radiologist double reading resulted in similar increases in sensitivity as those previously reported in radiologist double reading studies. Radiologist review of radiographer reported abnormalities is a suitable means by which to limit excess recall.

Radiographers as film readers in screening mammography: an assessment of competence under test and screening conditions

The aim of this study was to investigate the potential of radiographers as film readers in screening mammography. Seven radiographers received training in mammogram interpretation at a National Health Service (NHS) Breast Screening Training Centre. Film reading performance was assessed over a period of 1 year after training with test sets of selected screening mammograms. Actual screening performance on contemporary screening mammograms was monitored after training in relation to radiologist decisions and screening outcome. It was found that trained radiographers read mammograms to a standard comparable with that of radiologists. Film reading skills were maintained consistently over the period of this study and transferred to actual screening performance. It was concluded that radiographers could play a useful role as second readers in screening mammography. Training needs have to be assessed in relation to the role the film reading radiographer is to adopt.

Investigation of thermoregulatory characteristics in patients with Prader-Willi syndrome

A survey instrument is used to assess temperature regulation characteristics in children with Prader-Willi syndrome (PWS) compared to 3 control groups: sibs of PWS patients (SIB), neurodevelopmentally handicapped children (ND), and age and gender matched well children (WC). Significant differences were found between PWS patients, SIB controls, and WC controls in the prevalence of febrile convulsions, fever-associated symptoms, and temperature less than 94 degrees F. No differences were noted in any variable between the PWS patients and the ND controls, suggesting that these abnormalities are not unique to PWS, but can occur in any neurodevelopmentally handicapped individual, further suggesting these do not necessarily reflect syndrome-specific hypothalamic abnormalities.

Meal composition affects postprandial fatty acid oxidation

Pages R1065–R1070: D. M. Surina, W. Langhans, R. Pauli, and C. Wenk. “Meal composition affects postprandial fatty acid oxidation.” Results from a similar experiment performed after this article went to press have led the authors to conclude that the β-hydroxybutyrate values reported in this article are unreliable. They are probably skewed by high plasma triglyceride levels. The authors deeply regret this error and request that the readers disregard the related interpretations.

Meal composition affects postprandial fatty acid oxidation

The influence of macronutrient content of a meal on postprandial fatty acid oxidation was investigated in 13 Caucasian males after consumption of a high-fat (HF) breakfast (33% carbohydrate, 52% fat, 15% protein) and after an equicaloric high-carbohydrate (HC) breakfast (78% carbohydrate, 6% fat, 15% protein). The HF breakfast contained short- and medium-chain fatty acids, as well as long-chain fatty acids. Respiratory quotient (RQ) and plasma beta-hydroxybutyrate (BHB) were measured during the 3 h after the meal as indicators of whole body substrate oxidation and hepatic fatty acid oxidation, respectively. Plasma levels of free fatty acids (FFA), triglycerides, glucose, insulin, and lactate were also determined because of their relationship to nutrient utilization. RQ was significantly lower and plasma BHB was higher after the HF breakfast than after the HC breakfast, implying that more fat is burned in general and specifically in the liver after an HF meal. As expected, plasma FFA and triglycerides were higher after the HF meal, and insulin and lactate were higher after the HC meal. In sum, oxidation of ingested fat occurred in response to a single HF meal.

Arbovirus investigations in Argentina, 1977-1980. IV. Serologic surveys and sentinel equine program

Serologic surveys of wild and domestic birds, wild mammals, and horses were conducted during arbovirus field studies in Argentina from 1977 through 1980, a non-epizootic interval. The prevalence of neutralizing antibodies to eastern equine encephalitis (EEE) was consistently higher than to western equine encephalitis (WEE) virus in all species and all areas. The presence of antibodies in short-lived avian species and in young unvaccinated horses and the demonstration of seroconversions in horses during the period, indicated that these viruses are either enzootic in, or annually reintroduced into, Argentina. Antibodies to AG80-646, a new subtype of WEE virus isolated in the subtropical north (Chaco Province) from Culex (Melanoconion) mosquitoes, were found in horses and rodents in that region. Antibodies to the TC-83 strain of Venezuelan equine encephalitis (VEE) virus were found in all areas studied. The presence of antibodies in some horses was probably related to vaccination, but the demonstration of seroconversions in sentinel horses and of antibodies in birds and wild mammals indicates active transmission of VEE virus. In 1980 a new enzootic subtype of VEE virus (AG80-663) was isolated from mosquitoes in Chaco; neutralizing antibodies to this virus were prevalent in horses and rodents in this area. Infections with Aura and Una viruses were most common in the subtropical northern provinces. Infection with St. Louis encephalitis was prevalent and widespread, and birds, principally passerine and columbiform species, appear to be the principal hosts. An interesting and unexplained finding was the absence of arbovirus antibodies, in particular SLE antibodies in house sparrows (Passer domesticus). Antibody prevalences in horses exceeded 50% in all areas, and 12% of horses surveyed in Santa Fe Province developed antibody in a 17-month period. Antibodies to other flaviviruses were rare. A high prevalence of immunity to Maguari virus was found in horses; this agent is considered to be a potential equine pathogen. Antibodies to 2 new viruses, Barranqueras and Resistencia, which had been isolated from Cx. (Melanoconion) in Chaco Province, were found in rodents there. Immunity to Gamboa group viruses was prevalent, and birds were implicated as principal hosts.

Arbovirus investigations in Argentina, 1977-1980. I. Historical aspects and description of study sites

This is the introductory paper to a series on the ecology of arboviruses in Argentina. Epizootics of equine encephalitis have occurred since at least 1908, principally in the Pampa and Espinal biogeographic zones, with significant economic losses; human cases of encephalitis have been rare or absent. Both western equine and eastern equine encephalitis viruses have been isolated from horses during these epizootics, but the mosquitoes responsible for transmission have not been identified. A number of isolations of Venezuelan equine encephalitis (VEE) virus were reported between 1936 and 1958 in Argentina, but the validity of these findings has been seriously questioned. Nevertheless, serological evidence exists for human infections with a member of the VEE virus complex. Serological surveys conducted in the 1960s indicate a high prevalence of infection of humans and domestic animals with St. Louis encephalitis (SLE), and 2 SLE virus strains have been isolated from rodents. Human disease, however, has rarely been associated with SLE infection. Only 7 isolations of other arboviruses have been described (3 of Maguari, 1 of Aura, 2 of Una, and 1 of an untyped Bunyamwera group virus). In 1977, we began longitudinal field studies in Santa Fe Province, the epicenter of previous equine epizootics, and in 1980 we extended these studies to Chaco and Corrientes provinces. The study sites are described in this paper.