Population dynamics of phlebotomine sand flies (Diptera: Psychodidae) in cutaneous leishmaniasis endemic areas of Kurunegala District, Sri Lanka

Sand flies are the primary vectors of leishmaniasis. Disease management with effective vector control depends on the knowledge of vector population dynamics. In Sri Lanka, despite few isolated entomological collections, long-term studies are not reported to date. In the reported study, monthly entomological surveillance was conducted from May 2017 to December 2018 in Polpithigama, Maho, and Galgamuwa Medical Officer of Health (MOH) areas using standard entomological techniques. Climatic data were collected from the Department of Meteorology, Sri Lanka. Patient records were collected from each MOH office. A total of 38,339 sand flies were collected. The majority were Phlebotomus argentipes (99.50%, n = 38,147), while the rest was Sergentomyia punjabensis (0.50%, n = 192). Wind speed reduces sand fly abundance (r = -0.519, P < 0.05) evidently by limiting the movement. Rainfall increases sand fly abundance (r = 0.842, P <0.05, lag = 6 months) probably by improving favorable conditions in breeding sites. The actual effect of humidity is not conclusive without further research. The observed higher prevalence of leishmaniasis in the study sites could be due to the higher sand fly density in these areas. The number of patients shows a strong positive correlation (r = 0.516, P <0.05) to the sand fly abundance with a lag of 7 months. Systematic surveillance of sand flies as a part of general healthcare services is strongly recommended to identify and prevent possible outbreaks through timely planned vector control measures.

Socioeconomic, demographic and landscape factors associated with cutaneous leishmaniasis in Kurunegala District, Sri Lanka

Background

Leishmaniasis is a neglected tropical disease that affects countries in the developing world. In Sri Lanka, cutaneous leishmaniasis is the most common form of the disease. It is prevalent in dry and intermediate zones, mostly associated with rural settings. Understanding basic risk factors is critical in the management of the disease with effective interventions. This study is focused on assessing the demographic, socioeconomic and landscape factors associated with leishmaniasis in Kurunegala District, Sri Lanka.

Methods

A descriptive cross-sectional study was conducted. Households of the past patients and randomly selected households, which had no history of leishmaniasis cases were interviewed. The clinical, socioeconomic, demographic, landscape and awareness-related data were obtained using a pre-tested, interviewer-administered questionnaire.

Results

A total of 101 patients and a similar number of controls were included in the study. All the patients had the cutaneous form of the disease. Housewives and personnel with monthly incomes less than Rs. 10,000 (56.76 USD) were 3.9- and 9.5-times more prone to the disease, respectively, according to multivariate analysis. Presence of decaying garbage, termite hills, unclear areas, wet soil and gardening areas were always associated with the increased odds of acquiring the disease.

Conclusions

Demographic factors do not play a pivotal role in the prevalence of leishmaniasis in the area. Housewives, inhabitants with low incomes and individuals who live in areas with conditions suitable for sand fly breeding and resting are major groups with a higher risk of infection. Special attention must be given in raising awareness and environmental management in control activities.

Strong dose response after immunotherapy with PQ grass using conjunctival provocation testing

Background

Pollinex Quattro Grass (PQ Grass) is an effective, well-tolerated, short pre-seasonal subcutaneous immunotherapy to treat seasonal allergic rhinoconjunctivitis (SAR) due to grass pollen. In this Phase II study, 4 cumulative doses of PQ Grass and placebo were evaluated to determine its optimal cumulative dose.

Methods

Patients with grass pollen-induced SAR were randomised to either a cumulative dose of PQ Grass (5100, 14400, 27600 and 35600 SU) or placebo, administered as 6 weekly subcutaneous injections over 31-41 days (EudraCT number 2017-000333-31). Standardized conjunctival provocation tests (CPT) using grass pollen allergen extract were performed at screening, baseline and post-treatment to determine the total symptom score (TSS) assessed approximately 4 weeks after dosing. Three models were pre-defined (Emax, logistic, and linear in log-dose model) to evaluate a dose response relationship.

Results

In total, 95.5% of the 447 randomized patients received all 6 injections. A highly statistically significant (p < 0.0001), monotonic dose response was observed for all three pre-specified models. All treatment groups showed a statistically significant decrease from baseline in TSS compared to placebo, with the largest decrease observed after 27600 SU (p < 0.0001). The full course of 6 injections was completed by 95.5% of patients. Treatment-emergent adverse events were similar across PQ Grass groups, and mostly mild and transient in nature.

Conclusions

PQ Grass demonstrated a strong curvilinear dose response in TSS following CPT without compromising its safety profile.

Evaluation of rapid extraction and isothermal amplification techniques for the detection of Leishmania donovani DNA from skin lesions of suspected cases at the point of need in Sri Lanka

BACKGROUND

Leishmaniasis is a disease caused by vector-borne protozoans. In Sri Lanka, the cutaneous form of the disease is predominant, which is usually diagnosed using Giemsa-stained slit skin smear examination and by histology. However, the sensitivity of slit skin smears and histology are reportedly low. Moreover, facilities for the highly sensitive polymerase chain reaction (PCR) are available only in a few highly-equipped parasitology laboratories. Therefore, there is a need for low cost, sensitive and specific screening tests for diagnosis of leishmaniasis at the point of need.

RESULTS

In this study, a mobile suitcase laboratory applying novel extraction (SpeedXtract) and isothermal amplification and detection (recombinase polymerase amplification assay, RPA) methods were evaluated for the diagnosis of cutaneous leishmaniasis in Sri Lanka. First, the developed assay was applied to three different sample types (punch biopsy, slit skin smears and fine needle aspirates) at a local hospital. The results showed that the 2 mm punch biopsy sample produced the best exponential amplification curve and early fluorescence signal in the RPA assay. Secondly, punch biopsies were collected from 150 suspected cutaneous leishmaniasis cases and screened with SpeedXtract/RPA, RNAlater/PCR and ATL buffer/PCR, in addition to Giemsa-stained slit skin smears. Fifty-seven samples were negative in all detection methods. In total 93 samples were positive with assay sensitivities of 65.5% (SpeedXtract/RPA), 63.4% (RNAlater/PCR) and 92.4% (ATL buffer/PCR). The Giemsa-stained slit skin smear delivered the worst clinical sensitivity (32.2%).

CONCLUSIONS

The SpeedXtract/RPA method under field conditions took 35 min, while almost 8 h were needed to finalize the extraction and detection by PCR in the laboratory. The SpeedXtract/RPA method produced similar sensitivity to samples preserved in RNAlater and subjected to PCR amplification, but both were less sensitive than ATL-preserved samples subjected to PCR amplification. There is a need for a standardization of sample collection and nucleic acid extraction methods.

Randomized controlled trials define shape of dose response for Pollinex Quattro Birch allergoid immunotherapy

BACKGROUND

The Birch Allergoid, Tyrosine Adsorbate, Monophosphoryl Lipid A (POLLINEX^® Quattro Plus 1.0 ml Birch 100%) is an effective, well-tolerated short course subcutaneous immunotherapy. We performed 2 phase II studies to determine its optimal cumulative dose.

METHODS

The studies were conducted in Germany, Austria and Poland (EudraCT numbers: 2012-004336-28 PQBirch203 and 2015-000984-15 PQBirch204) using a wide range of cumulative doses. In both studies, subjects were administered 6 therapy injections weekly outside the pollen season. Conjunctival Provocation Tests were performed at screening, baseline and 3-4 weeks after completing treatment, to quantify the reduction in Total Symptom Scores (as the primary endpoint) with each cumulative dose. Multiple Comparison Procedure and Modeling analysis was used to test for the dose response, shape of the curve and estimation of the median effective dose (ED₅₀ ), a measure of potency.

RESULTS

Statistically significant dose responses (P < .01 & .001) were seen, respectively. The highest cumulative dose in PQBirch204 (27 300 standardized units [SU]) approached a plateau. Potency of the PQBirch was demonstrated by an ED₅₀ 2723 SU, just over half the current dose. Prevalence of treatment-emergent adverse events was similar for active doses, most being short-lived and mild. Compliance was over 85% in all groups.

CONCLUSION

Increasing the cumulative dose of PQBirch 5.5-fold from 5100 to 27 300 SU achieved an absolute point difference from placebo of 1.91, a relative difference 32.3% and an increase in efficacy of 50%, without compromising safety. The cumulative dose response was confirmed to be curvilinear in shape.

The epidemiology of soil-transmitted helminths in Bihar State, India

BACKGROUND

Soil-transmitted helminths (STHs) infect over a billion individuals worldwide. In India, 241 million children are estimated to need deworming to avert the negative consequences STH infections can have on child health and development. In February-April 2011, 17 million children in Bihar State were dewormed during a government-led school-based deworming campaign. Prior to programme implementation, a study was conducted to assess STH prevalence in the school-age population to direct the programme. The study also investigated risk factors for STH infections, including caste, literacy, and defecation and hygiene practices, in order to inform the development of complementary interventions.

METHODS

A cross-sectional survey was conducted among children in 20 schools in Bihar. In addition to providing stool samples for identification of STH infections, children completed a short questionnaire detailing their usual defecation and hand-hygiene practices. Risk factors for STH infections were explored.

RESULTS

In January-February 2011, 1279 school children aged four to seventeen provided stool samples and 1157 children also completed the questionnaire. Overall, 68% of children (10-86% across schools) were infected with one or more soil-transmitted helminth species. The prevalence of ascariasis, hookworm and trichuriasis was 52%, 42% and 5% respectively. The majority of children (95%) practiced open defecation and reported most frequently cleansing hands with soil (61%). Increasing age, lack of maternal literacy and certain castes were independently associated with hookworm infection. Absence of a hand-washing station at the schools was also independently associated with A. lumbricoides infection.

CONCLUSIONS

STH prevalence in Bihar is high, and justifies mass deworming in school-aged children. Open defecation is common-place and hands are often cleansed using soil. The findings reported here can be used to help direct messaging appropriate to mothers with low levels of literacy and emphasise the importance of water and sanitation in the control of helminths and other diseases.

Cluster-randomised trial of the impact of school-based deworming and iron supplementation on the cognitive abilities of schoolchildren in Sri Lanka's plantation sector

OBJECTIVE

To assess the impact of deworming and iron supplementation on the cognitive abilities and educational achievement of school-age children in Sri Lanka.

METHODS

Prospective, placebo-controlled randomised study. The treatment group received deworming and weekly iron supplementation for 6 months; the control group received placebo for both the anthelmintic and iron. A mixed effects regression model was used to answer the main research question. To increase the precision of this study's estimates, various background variables were controlled for that were not related to treatment but could have some impact on the outcome.

RESULTS

The prevalence of soil-transmitted helminth (STH) infection was reduced in the treatment group (n = 615), with significant differences between treatment and control groups (n = 575) in the levels of Ascaris and Trichuris. No impact was found on haemoglobin (Hb) levels, nor any significant impact on concentration levels or on educational test scores.

CONCLUSION

Decline in STH prevalence alone, in the absence of improved Hb status, produced no evidence of impact on concentration levels or educational test scores.

Evaluation of PCR-ELISA as a tool for monitoring transmission of Wuchereria bancrofti in District of Gampaha, Sri Lanka

OBJECTIVE

To compare Wuchereria bancrofti (W. bancrofti) infection rates of Culex quinquefasciatus, using dissection and PCR-ELISA in two consecutive time periods (from 2007 to 2008 and from 2008 to 2009).

METHODS

Mosquitoes were collected in 30 sentinel and 15 non-sentinel sites in 15 Medical Officer of Health areas of Gampaha District known for the presence of W. bancrofti transmission in two consecutive time period of 2007 to 2008 and 2008 to 2009. Captured mosquitoes were dissected to determine the W. bancrofti larvae (L1, L2, L3). PCR was carried out using DNA extracted from mosquito pools (15 body parts/pool) utilizing the primers specific for Wb-SspI repeat. PCR products were analyzed by hybridization ELISA using fluorescein-labeled wild type specific probes. The prevalence of infected/infective mosquitoes in PCR pools (3 pools/site) was estimated using the PoolScreen™ algorithm and a novel probability-based method.

RESULTS

Of 45 batches of mosquitoes dissected, W. bancrofti infected mosquitoes were found in 19 and 13 batches, with an infection rate of 13.29% and 3.10% with mean larval density of 8.7 and 1.0 larvae per mosquito for two study periods in the Gampaha District. Total of 405 pools of head, thorax and abdomen were processed by PCR-ELISA for each year. Of these, 51 and 31 pools were positive for W. bancrofti in the two study periods respectively. The association of dissection based prevalence rates with PCR based rates as determined by the Pearson correlation coefficient were 0.176 and 0.890 respectively for the two periods.

CONCLUSIONS

Data indicate that PCR-ELISA is more sensitive than the traditional dissection techniques for monitoring transmission intensity.

Soil-transmitted helminth infections among plantation sector schoolchildren in Sri Lanka: prevalence after ten years of preventive chemotherapy

Background

The plantation sector in Sri Lanka lags behind the rest of the country in terms of living conditions and health. In 1992, a sector-wide survey of children aged 3–12 years and women of reproductive age showed >90% prevalence of soil-transmitted helminth infections. Biannual mass de-worming targeting children aged 3–18 years started in 1994 and was continued until 2005. The present study was carried out to assess the status of infection four years after cessation of mass de-worming.

Methods/Findings

A school-based cross-sectional survey was carried out. Faecal samples from approximately 20 children from each of 114 schools in five districts were examined using the modified Kato-Katz technique. Data regarding the school, the child's family and household sanitation were recorded after inspection of schools and households. Multivariate analysis was carried out using logistic regression, to identify risk factors for infection. Faecal samples were obtained from 1890 children. In 4/5 districts, >20% were infected with one or more helminth species. Overall combined prevalence was 29.0%; 11.6% had infections of moderate-heavy intensity. The commonest infection was Ascaris lumbricoides, present in all five districts, as was Trichuris trichiura. Hookworm was not detected in two districts. Multivariate analysis identified low altitude and maternal under-education as risk factors for all three infections. Poor household sanitation was identified as a risk factor for A. lumbricoides and hookworm, but not T. trichiura infections.

Conclusions/Significance

The results indicate that regular mass de-worming of plantation sector children should be resumed along with more emphasis on better sanitation and health education. They show that even after 10 years of mass chemotherapy, prevalence can bounce back after cessation of preventive chemotherapy, if the initial force of transmission is strong and other long-term control measures are not concomitantly implemented.

Mass de-worming of pre-school and school-age children was introduced in Sri Lanka's plantation sector in 1994 after a survey showed that >90% of children and women of reproductive age were infected with intestinal worms. The present study was carried out to assess the status of infection four years after mass de-worming was stopped in 2005 due to lack of funds. Approximately 20 children from each of 114 schools in five districts were examined. Data regarding the school, the child's family and household sanitation were recorded. Faecal samples from 1890 children were examined for worm eggs. In 4/5 districts, >20% were found infected with one or more intestinal worm. Overall, 29.0% of children were infected and 11.6% of these had moderate–heavy worm burdens. The commonest infection was roundworm, followed by whipworm. Hookworm was not detected in two districts. Statistical analysis identified low altitude, maternal under-education and poor household sanitation as risk factors for infection. The results indicate that when initial infection rates are very high, in the absence of marked improvements in sanitation and health education, even 10 years of biannual mass de-worming may not be enough to prevent resurgence of infection after cessation of mass de-worming.

The monoterpenes of Artemisia tridentata ssp. vaseyana, Artemisia cana ssp. viscidula and Artemisia tridentata ssp. spiciformis

Monoterpenes from three different members of the Anthemideae family, Artemisia tridentata ssp. vaseyana, Artemisia cana ssp. viscidula and Artemisia tridentata ssp. spiciformis were isolated and their structures determined using spectroscopic techniques. A total of 26 irregular and regular monoterpenes were identified. Among these, 20 had previously been identified in the Anthemideae family. Of the remaining six, four were known, but previously unidentified in this family. 2,2-Dimethyl-6-isopropenyl-2H-pyran, 2,3-dimethyl-6-isopropyl-4H-pyran and 2-isopropenyl-5-methylhexa-trans-3,5-diene-1-ol were isolated from both A. tridentata ssp. vaseyana and A. cana ssp. viscidula. The irregular monoterpene 2,2-dimethyl-6-isopropenyl-2H-pyran has a carbon skeleton analogous to the biologically important triterpene squalene. Two additional irregular monoterpenes, artemisia triene and trans-chrysanthemal were isolated from A. cana ssp. viscidula and lavandulol was isolated from A. tridentata ssp. spiciformis. This is the first time a compound possessing a lavandulyl-skeletal type has been found in the Anthemideae family.

Pharmacokinetics and pharmacodynamics of epoetin alfa once weekly and three times weekly

OBJECTIVE

To compare the pharmacokinetics, pharmacodynamics, and tolerance of epoetin alfa administered subcutaneously (s.c.) once weekly (q.w.) and three times weekly (t.i.w.).

METHODS

An open-label, randomized, parallel-design study was conducted in 36 healthy adults with hemoglobin (Hb) levels of 11.7 14.0 g/dl for women and 13.0-14.8 g/dl for men. Subjects were randomized to epoetin alfa 150 IU/kg s.c. t.i.w. or 40,000 IU s.c. q.w. for 4 weeks. Serum erythropoietin concentrations were measured using a validated enzyme-linked immunosorbent assay (ELISA). Pharmacokinetic parameters [peak serum concentration (Cmax), mean predose trough concentration (Cmin), time to Cmax (tmax), clearance after s.c. administration (CL/F), area under the plasma concentration time curve (AUC), and terminal elimination half-life (t 1/2)] were calculated using model-independent methods. Mean changes from baseline and AUC of percentage reticulocytes, Hb, and total red blood cell (RBC) concentrations over the 1-month study period were calculated.

RESULTS

The Cmax values for serum epoetin alfa q.w. were six times and AUC(0-168) values three times that of the t.i.w. regimen. Time profiles of changes in percentage reticulocytes, Hb, and total RBC over 1 month were similar between regimens. The rate of increase in Hb was similar for the two groups, and both groups exhibited a 3.1-g/dl increase in mean Hb levels from baseline through day 29. Changes in ferritin levels were generally similar between groups and reflected expected use of iron stores for Hb production. Epoetin alfa administered t.i.w. or q.w. was well tolerated and no serious adverse events occurred.

CONCLUSION

The pharmacodynamic responses were equivalent between groups despite expected differences in total erythropoietin exposure. These results indicate that the epoetin alfa 150 IU/kg t.i.w. and 40,000 IU q.w. regimens can be considered clinically equivalent.

Vitamin E and other antioxidants inhibit human prostate cancer cells through apoptosis

BACKGROUND

Many human prostate cancer cells have escaped the apoptotic effects of natural regulators of cell growth such as transforming growth factor betal (TGF beta-1) and tumor necrosis factor (TNF).

METHODS

Prostate cancer cell growth was investigated by treating with antioxidants. DU-145 (androgen-unresponsive), LNCaP (androgen-responsive), and ALVA-101 (androgen moderately responsive) were grown in RPMI-1640 medium supplemented with bovine fetal calf serum and antibiotics, and were treated with various antioxidants for 1-7 days. Cell growth was then determined with the Cell Titer 96 AQ assay, and apoptosis was assessed by cell death detection ELISA, nuclear morphology, and TUNEL techniques.

RESULTS

Cells treated with or without (+/-)-alpha-tocopherol (vitamin E) for 1-7 days at concentrations from 0.078-2.5 microg/ml modestly affected cell growth compared to other antioxidants tested. Tocopherol produced a significant (P < 0.01) inhibition of ALVA-101 and LNCaP (10-24% of control; 0.078-2.5 microg/ml; at 6 days; n = 6). DU-145 cells were not growth-inhibited significantly. However, pyrrolidinedithiocarbamate (PDTC) produced a significant (P < 0.01, n = 6; 17-80% of control; 2.5-20 microg/ml; 1-7 days) inhibition of DU-145 and ALVA-101 cells. A significant (P < 0.01) and maximum inhibition of LNCaP cells occurred at all concentration of PDTC (2. 5-20 microg/ml). A third compound, diethyldithiocarbamic acid (DETC), incubated for 1-7 days, produced a significant dose response suppression of cell growth of DU-145 and ALVA-101 cells (P < 0.01; 14-88% of control; 1.25-80 microg/ml; n = 6). LNCaP cells were inhibited by DETC (P < 0.01; 28% of control; 1.25-80 microg/ml; n = 6). All three antioxidants tested stimulated apoptosis in actively dividing ALVA-101, DU-145, and LNCaP cells (P < 0.01; n = 6), but confluent cells were affected less. Testosterone had additive inhibitory effects when combined with PDTC in ALVA-101 cells; however, the other cell lines were not influenced.

CONCLUSIONS

These results demonstrate that antioxidants modulate human prostate cancer cell proliferation by altering apoptosis in dividing cells, and this necrosis or apoptosis in confluent cells is not as effective.