Ajay R. Bharti

Leptospirosis: a zoonotic disease of global importance

In the past decade, leptospirosis has emerged as a globally important infectious disease. It occurs in urban environments of industrialised and developing countries, as well as in rural regions worldwide. Mortality remains significant, related both to delays in diagnosis due to lack of infrastructure and adequate clinical suspicion, and to other poorly understood reasons that may include inherent pathogenicity of some leptospiral strains or genetically determined host immunopathological responses. Pulmonary haemorrhage is recognised increasingly as a major, often lethal, manifestation of leptospirosis, the pathogenesis of which remains unclear. The completion of the genome sequence of Leptospira interrogans serovar lai, and other continuing leptospiral genome sequencing projects, promise to guide future work on the disease. Mainstays of treatment are still tetracyclines and beta-lactam/cephalosporins. No vaccine is available. Prevention is largely dependent on sanitation measures that may be difficult to implement, especially in developing countries.

Malaria Diagnosis by a Polymerase Chain Reaction–Based Assay Using a Pooling Strategy

Pooling clinical specimens reduces the number of assays needed when screening for infectious diseases. Polymerase chain reaction (PCR)-based assays are the most sensitive tests to diagnose malaria, but its high cost limits its use. We adapted a pooling platform that could reduce the number of assays needed to detect malaria infection. To evaluate this platform, two sets of 100 serum samples, with 1% and 5% malaria prevalence, were tested. DNA, extracted from pooled samples, was amplified by malaria-specific PCR. Additional validation was performed by determining the level of PCR detection based on 1:10 and 1:100 dilution. The platform correctly detected all malaria samples in the two test matrices. The use of stored serum samples also has important implications for studies investigating malaria prevalence rates retrospectively. Field studies, using serum and whole blood specimens, are needed to validate this technique for the adaptation of these methods for clinical utility.

Plasma and Cerebrospinal Fluid Biomarkers Predict Cerebral Injury in HIV-Infected Individuals on Stable Combination Antiretroviral Therapy.

Objectives:HIV-associated brain injury persists despite combination antiretroviral therapy, but contributing factors remain poorly understood. We postulated that inflammation-associated biomarkers will be associated with cerebral injury on proton magnetic resonance spectroscopy in chronically HIV-infected subjects. Methods:Five biomarkers were measured in 197 HIV-infected subjects: soluble CD14, MCP-1, IP-10, MIP-1&bgr;, and fractalkine. Levels of N-acetyl aspartate (NAA), Choline (Cho), Myoinositol (MI), Glutamate + Glutamine (Glx), and Creatine (Cr) were acquired in the midfrontal cortex (MFC), frontal white matter, and basal ganglia (BG). Predictive models were built through linear regression, and the best models were chosen using the Akaike Information Criterion. Results:Increases in plasma or CSF MCP-1 were associated with lower NAA/Cr in the MFC and BG, whereas metabolite changes in the frontal white matter for NAA/Cr, GlxCr, and Cho/Cr were explained almost exclusively by a single factor, sCD14. Plasma and CSF levels of this factor were also significantly associated with Glx/Cr in MFC and BG. Higher CSF FKN was associated with higher NAA/Cr in BG. Best predictors for higher Cho/Cr in BG and MFC were CSF sCD14 and CSF MIP-1&bgr;. Plasma and CSF IP-10 were only associated with Cho/Cr in MFC. Of the 3 models that simultaneously accounted for both plasma and CSF, there were more associations between CSF biomarkers and magnetic resonance spectroscopy metabolites. Conclusions:Markers of inflammation and immune activation, in particular MCP-1 and sCD14, predominantly reflecting CNS sources, contribute to the persistence of brain injury in a metabolite and region-dependent manner in chronically HIV-infected patients on stable combination antiretroviral therapy.

Correlates of HIV and malaria co-infection in Southern India

BackgroundMalaria and HIV co-infection adversely impact the outcome of both diseases and previous studies have mostly focused on falciparum malaria. Plasmodium vivax contributes to almost half of the malaria cases in India, but the disease burden of HIV and P. vivax co-infection is unclear.MethodsHIV-infected subjects (n=460) were randomly selected from the 4,611 individuals seen at a Voluntary Counseling and Testing Center in Chennai, India between Jan 2 to Dec 31 2008. Malaria testing was performed on stored plasma samples by nested PCR using both genus-specific and species-specific primers and immunochromatography-based rapid diagnostic test for detecting antibodies against Plasmodium falciparum and P. vivax.ResultsRecent malaria co-infection, defined by the presence of antibodies, was detected in 9.8% (45/460) participants. Plasmodium vivax accounted for majority of the infections (60%) followed by P. falciparum (27%) and mixed infections (13%). Individuals with HIV and malaria co-infection were more likely to be men (p=0.01). Between those with and without malaria, there was no difference in age (p=0.14), CD4+ T-cell counts (p=0.19) or proportion CD4+ T-cell below 200/mL (p=0.51).ConclusionsRetrospective testing of stored plasma samples for malaria antibodies can facilitate identification of populations with high rates of co-infection, and in this southern India HIV-infected cohort there was a considerable burden of malaria co-infection, predominantly due to P. vivax. However, the rate of P. falciparum infection was more than 6-fold higher among HIV-infected individuals than what would be expected in the general population in the region. Interestingly, individuals co-infected with malaria and HIV were not more likely to be immunosuppressed than individuals with HIV infection alone.

Clinical variables identify seronegative HCV co-infection in HIV-infected individuals.

BACKGROUND A substantial number of people living with HIV (PLWH) are co-infected with Hepatitis C Virus (HCV) but have a negative screening HCV antibody test (seronegative HCV infection, or SN-HCV). OBJECTIVE To identify a concise set of clinical variables that could be used to improve case finding for SN-HCV co-infection among PLWH. STUDY DESIGN Two hundred HIV-infected participants of the CHARTER study were selected based on 7 clinical variables associated with HCV infection but were HCV seronegative. Data were analyzed using Fishers exact tests, receiver-operating characteristic (ROC) curves, and logistic regression. RESULTS Twenty-six (13%) participants had detectable HCV RNA. SN-HCV was associated with a history of IDU, elevated ALT and AST, low platelets, black ethnicity, and undetectable HIV RNA in plasma. Each of these clinical variables, except for abnormal AST, remained independently associated with SN-HCV in a multivariate logistic regression analysis. A composite risk score correctly identified SN-HCV with sensitivity up to 85% and specificity up to 88%. CONCLUSIONS In a substantial minority of PLWH, seronegative HCV viremia can be predicted by a small number of clinical variables. These findings, after validation in an unselected cohort, could help focus screening in those at highest risk.

Saccharomyces cerevisiae Laryngitis and Oral Lesions in a Patient with Laryngeal Carcinoma

Saccharomyces cerevisiae is increasingly being promoted as a nutritional supplement by health food enthusiasts and is also recommended as prophylaxis against antibiotic-associated diarrhea. However, severe opportunistic infections due to S. cerevisiae have been reported in patients with chronic disease, cancer, and immunosuppression. Fungemia, endocarditis, pneumonia, peritonitis, urinary tract infections, skin infections, and esophagitis have been described. It is important to consider infections due to S. cerevisiae in appropriate clinical settings. Here, we describe the first case of S. cerevisiae laryngitis in a patient with a history of laryngeal carcinoma who also had oral lesions.

Fibroblast growth factors 1 and 2 in cerebrospinal fluid are associated with HIV disease, methamphetamine use, and neurocognitive functioning.

Background Human immunodeficiency virus (HIV) and methamphetamine use commonly affect neurocognitive (NC) functioning. We evaluated the relationships between NC functioning and two fibroblast growth factors (FGFs) in volunteers who differed in HIV serostatus and methamphetamine dependence (MAD). Methods A total of 100 volunteers were categorized into four groups based on HIV serostatus and MAD in the prior year. FGF-1 and FGF-2 were measured in cerebrospinal fluid by enzyme-linked immunosorbent assays along with two reference biomarkers (monocyte chemotactic protein [MCP]-1 and neopterin). Comprehensive NC testing was summarized by global and domain impairment ratings. Results Sixty-three volunteers were HIV+ and 59 had a history of MAD. FGF-1, FGF-2, and both reference biomarkers differed by HIV and MAD status. For example, FGF-1 levels were lower in subjects who had either HIV or MAD than in HIV− and MAD− controls (P=0.003). Multivariable regression identified that global NC impairment was associated with an interaction between FGF-1 and FGF-2 (model R2=0.09, P=0.01): higher FGF-2 levels were only associated with neurocognitive impairment among subjects who had lower FGF-1 levels. Including other covariates in the model (including antidepressant use) strengthened the model (model R2=0.18, P=0.004) but did not weaken the association with FGF-1 and FGF-2. Lower FGF-1 levels were associated with impairment in five of seven cognitive domains, more than FGF-2, MCP-1, or neopterin. Conclusion These findings provide in vivo support that HIV and MAD alter expression of FGFs, which may contribute to the NC abnormalities associated with these conditions. These cross-sectional findings cannot establish causality and the therapeutic benefits of recombinant FGF-1 need to be investigated.

Higher Anti-Cytomegalovirus Immunoglobulin G Concentrations Are Associated With Worse Neurocognitive Performance During Suppressive Antiretroviral Therapy

Background Cytomegalovirus (CMV) has been linked to higher risk of cardiovascular disease and mortality. We aimed to determine if CMV is associated with neurocognitive performance in adults infected with human immunodeficiency virus (HIV). Methods In this cross-sectional analysis, anti-CMV immunoglobulin G (IgG) concentrations in blood and CMV DNA copies in blood and cerebrospinal fluid (CSF) were measured in stored specimens of 80 HIV-infected adults who were previously assessed with a comprehensive neurocognitive test battery. Thirty-eight were taking suppressive antiretroviral therapy (ART) and 42 were not taking ART. A panel of 7 soluble biomarkers was measured by immunoassay in CSF. Results Anti-CMV IgG concentrations ranged from 5.2 to 46.1 IU/mL. CMV DNA was detected in 7 (8.8%) plasma specimens but in no CSF specimens. Higher anti-CMV IgG levels were associated with older age (P = .0017), lower nadir CD4+ T-cell count (P < .001), AIDS (P < .001), and higher soluble CD163 (P = .009). Higher anti-CMV IgG levels trended toward an association with worse neurocognitive performance overall (P = .059). This correlation was only present in those taking suppressive ART (P = .0049). Worse neurocognitive performance remained associated with higher anti-CMV IgG levels after accounting for other covariates in multivariate models (model P = .0038). Detectable plasma CMV DNA was associated with AIDS (P = .05) but not with neurocognitive performance. Conclusions CMV may influence neurocognitive performance in HIV-infected adults taking suppressive ART. Future clinical trials of anti-CMV therapy should help to determine whether the observed relationships are causal.

314 EXPERIMENTAL INFECTION OF ANOPHELES DARLINGI MOSQUITOES BY PLASMODIUM VIVAX FROM NATURALLY INFECTED PATIENTS IN THE PERUVIAN AMAZON.

Purpose of Study In Peru, the incidence of malaria has increased dramatically since the early 1990s and Plasmodium vivax remains the predominant species. Although P. vivax does not cause life-threatening disease, it is still a considerable source of morbidity but has been widely understudied. This study was conducted to determine the transmission patterns of P. vivax from naturally infected patients in the Peruvian Amazon to Anopheles darlingi mosquitoes. Methods The study was conducted over a period of 14 months from May 2004 to June 2005 and included symptomatic patients with P. vivax malaria from Iquitos, Peru. The widely used artificial membrane feeding method was used to infect mosquitoes. Mosquito midguts were dissected after a week and oocysts were counted by microscopic examination. Summary of Results A total of 102 patients with symptomatic P. vivax infection were enrolled in the study. Approximately 50% (50/102) of the patients were febrile, with a temperature of 37.7°C or more. Pallor was noted in 64.7% (66/102) patients. Gametocytemia ranged from 0-106 with a mean of 20.61. A total of 4,017 mosquitoes successfully fed on the blood using the artificial membrane feeding technique, with 2,631 (65%) surviving until the time of midgut dissection. Approximately 50% (52/102) of the patient specimens infected mosquitoes and 23% (602/2,631) of the mosquitoes had at least one reported oocyst. The mean oocyst load per infected midgut was 21.1 with a range of 0-395. Conclusions This is the first study of its kind conducted in the Peruvian Amazon. There were 2 important observations: (1) only half of the patients were able to infect mosquitoes and (2) there was substantial variation in the transmission of infection to mosquitoes as measured by oocyst loads and percentage mosquitoes infected. Determining factors that affect transmission (eg, anemia, gametocyte count and maturity, fever, anti-inflammatory medications, antigametocyte antibodies) will help identify alternative interventions that can be used in addition to the current control measures. Patients who are more efficient transmitters can then be targeted first for these interventional methods.