Sensitivity and specificity of the Leishmania OligoC-TesT and NASBA-oligochromatography for diagnosis of visceral leishmaniasis in Kenya.

OBJECTIVE: To estimate the sensitivity and specificity of the OligoC-TesT and nucleic acid sequence-based amplification coupled to oligochromatography (NASBA-OC) for molecular detection of Leishmania in blood from patients with confirmed visceral leishmaniasis (VL) and healthy endemic controls from Kenya. METHODS: Blood specimens of 84 patients with confirmed VL and 98 endemic healthy controls from Baringo district in Kenya were submitted to both assays. RESULTS: The Leishmania OligoC-TesT showed a sensitivity of 96.4% (95% confidence interval [CI]: 90-98.8%) and a specificity of 88.8% (95% CI: 81-93.6%), while the sensitivity and specificity of the NASBA-OC were 79.8% (95% CI: 67-87%) and 100% (95% CI: 96.3-100%), respectively. CONCLUSION: Our findings indicate high sensitivity of the Leishmania OligoC-TesT on blood while the NASBA-OC is a better marker for active disease.

Spatial clustering and epidemiological aspects of visceral leishmaniasis in two endemic villages, Baringo District, Kenya.

Visceral leishmaniasis (VL) seroprevalence in Kenya is unknown because of the lack of a practical and accurate diagnostic test or surveillance system. A novel serological assay was used to estimate the seroprevalence of Leishmania-specific antibodies, and Global Information System and spatial clustering techniques were applied to study the presence of spatial clusters in Parkarin and Loboi villages in Baringo District in 2001. VL seroprevalences were 52.5% in Parkarin and 16.9% in Loboi. Significant associations among seropositivity and house construction, age, and proximity to domestic animal enclosures were found. A significant spatial cluster of VL was found in Loboi. The spatial distribution of cases in the two villages was different with respect to risk factors, such as presence of domestic animals. This study suggests that disease control efforts could be focused on elimination of sand fly habitat, placement of domestic animal enclosures, and targeted use of insecticides.

A phase II dose-increasing study of sitamaquine for the treatment of visceral leishmaniasis in Kenya.

Sitamaquine (WR6026) is an 8-aminoquinoline in development for the oral treatment of visceral leishmaniasis (VL). This was an open-label, dose-increasing study to determine the dose-response and safety profile for sitamaquine in Kenyan patients with VL caused by Leishmania donovani. Patients (mean age 15.9 [range = 5-47] years) received sitamaquine daily for 28 days at one of four doses: 1.75 (n = 12), 2.0 (n = 61), 2.5 (n = 12), or 3.0 (n = 12) mg/kg/day. The primary efficacy outcome was cure (absence of parasites on splenic aspirate) in the intent-to-treat population at day 180. Cure was achieved in 79 (83%) of 95 patients overall, and in 11 (92%) of 12, 49 (80%) of 61, 9 (82%) of 11, and 10 (91%) of 11 patients at sitamaquine doses of 1.75, 2.0, 2.5, or 3.0 mg/kg/day, respectively. The most frequent adverse events during active treatment were abdominal pain (12 [12%] of 97) and headache (11 [11%] of 97), and one patient in each of the 2.5 mg/kg/day and 3.0 mg/kg/day dose groups had a severe renal adverse event. The effects of sitamaquine on the kidney need further investigation. Sitamaquine was efficacious and generally well tolerated in Kenyan patients with VL.

The Number and Complexity of Pure and Recombinant HIV-1 Strains Observed within Incident Infections during the HIV and Malaria Cohort Study Conducted in Kericho, Kenya, from 2003 to 2006.

Characterization of HIV-1 subtype diversity in regions where vaccine trials are conducted is critical for vaccine development and testing. This study describes the molecular epidemiology of HIV-1 within a tea-plantation community cohort in Kericho, Kenya. Sixty-three incident infections were ascertained in the HIV and Malaria Cohort Study conducted in Kericho from 2003 to 2006. HIV-1 strains from 58 of those individuals were full genome characterized and compared to two previous Kenyan studies describing 41 prevalent infections from a blood bank survey (1999-2000) and 21 infections from a higher-risk cohort containing a mix of incident and prevalent infections (2006). Among the 58 strains from the community cohort, 43.1% were pure subtypes (36.2% A1, 5.2% C, and 1.7% G) and 56.9% were inter-subtype recombinants (29.3% A1D, 8.6% A1CD, 6.9% A1A2D, 5.2% A1C, 3.4% A1A2CD, and 3.4% A2D). This diversity and the resulting genetic distance between the observed strains will need to be addressed when vaccine immunogens are chosen. In consideration of current vaccine development efforts, the strains from these three studies were compared to five candidate vaccines (each of which are viral vectored, carrying inserts corresponding to parts of gag, pol, and envelope), which have been developed for possible use in sub-Saharan Africa. The sequence comparison between the observed strains and the candidate vaccines indicates that in the presence of diverse recombinants, a bivalent vaccine is more likely to provide T-cell epitope coverage than monovalent vaccines even when the inserts of the bivalent vaccine are not subtype-matched to the local epidemic.

Visceral leishmaniasis: current status of control, diagnosis, and treatment, and a proposed research and development agenda.

Visceral leishmaniasis is common in less developed countries, with an estimated 500000 new cases each year. Because of the diversity of epidemiological situations, no single diagnosis, treatment, or control will be suitable for all. Control measures through case finding, treatment, and vector control are seldom used, even where they could be useful. There is a place for a vaccine, and new imaginative approaches are needed. HIV co-infection is changing the epidemiology and presents problems for diagnosis and case management. Field diagnosis is difficult; simpler, less invasive tests are needed. Current treatments require long courses and parenteral administration, and most are expensive. Resistance is making the mainstay of treatment, agents based on pentavalent antimony, useless in northeastern India, where disease incidence is highest. Second-line drugs (pentamidine and amphotericin B) are limited by toxicity and availability, and newer formulations of amphotericin B are not affordable. The first effective oral drug, miltefosine, has been licensed in India, but the development of other drugs in clinical phases (paromomycin and sitamaquine) is slow. No novel compound is in the pipeline. Drug combinations must be developed to prevent drug resistance. Despite these urgent needs, research and development has been neglected, because a disease that mainly affects the poor ranks as a low priority in the private sector, and the public sector currently struggles to undertake the development of drugs and diagnostics in the absence of adequate funds and infrastructure. This article reviews the current situation and perspectives for diagnosis, treatment, and control of visceral leishmaniasis, and lists some priorities for research and development.

Comparison of short-term and long-term protocols for stabilization and preservation of RNA and DNA of Leishmania, Trypanosoma, and Plasmodium.

Molecular tools continue to be important in the prevention and control of parasitic diseases. However, using these techniques directly in the field remains a major challenge. Therefore, the preservation of clinical samples collected from endemic field areas for later analysis remains an important preanalytical process. This study aimed at identifying a suitable protocol for stabilization and preservation of RNA and DNA in bioclinical specimens for Trypanosoma, Leishmania, and Plasmodium research. Both spiked and unspiked blood samples were preserved in 7 protocols (different media; storage temperatures). Samples were evaluated for possible degradation of DNA and RNA along the storage duration up to the 10th week. Nucleic acid targets were assessed as follows: (i) Trypanosoma and Plasmodium RNA analysis was done using real-time nucleic acid sequence-based amplification (RT-NASBA) for 18S rRNA and for stage-specific Pfs25 mRNA, respectively; (ii) Trypanosoma DNA assessment analysis was conducted by using a conventional PCR for 18S rDNA; (iii) Leishmania RNA analysis was performed with a quantitative NASBA for 18S rRNA and Leishmania DNA assessment with an RT-PCR for 18S rDNA. Findings suggested that a newly developed L3™ buffer proved to be reliable and suitable for both short- and long-term preservation of parasite nucleic acid material. This buffer is envisaged to be suitable for utilization in field situations where resources are limited.

HIV-1 incidence rates and risk factors in agricultural workers and dependents in rural Kenya: 36-month follow-up of the Kericho HIV cohort study.

BACKGROUND: Incidence data from prospective cohort studies using rigorous laboratory methods are important in designing and evaluating HIV vaccine and therapeutic clinical trials and health care programs. We report 36-month HIV-1 incidence rates and demographic and psychosocial risks from the Kericho cohort in rural Kenya's southern Rift Valley Province. METHODS: Thirty-six month, prospective, closed, observational cohort study of adult plantation workers and dependents followed biannually. HIV-1 incidence rates per 100 person-years (py) were calculated, and Cox regression analyses were used to estimate hazards ratios (HR) associated with seroconversion. RESULTS: Two thousand four hundred volunteers (mean age +/- SD = 30.1 +/- 8.5 years; 36.5% women) participated. Twenty-nine new HIV cases were identified in year 1 of follow-up, which increased to cumulative totals of 49 and 63 cases in years 2 and 3, respectively. The corresponding 1-, 2-, and 3-year incidence rates were 1.41 [95% confidence interval (CI) = 0.95-2.02], 1.16 (95% CI = 0.86-1.54), and 1.00 (95% CI = 0.77-1.28) per 100 py. Risk factors associated with HIV seroconversion included the following: of the Luo tribe (HR = 3.31; 95% CI = 1.65-6.63), marriage more than once (HR = 2.83; 95% CI = 1.20-6.69), self-reported male circumcision (HR = 0.32; 95% CI = 0.17-0.60), history of sexually transmitted infection (HR = 2.40; 95% CI = 1.09-5.26), history of substance abuse during sex (HR = 2.44; 95% CI = 1.16-5.13), and history of transactional sex (HR = 3.30; 95% CI = 1.79-6.09). CONCLUSIONS: HIV-1 incidence rates were relatively low in adult plantation workers and dependents in rural Kenya. Cohorts including higher risk populations (eg, commercial sex workers) warrant consideration for regional HIV preventive vaccine trials. Even low incidence, well-described cohorts generate valuable epidemiological clinical trial data.