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VDR polymorphism, gene expression and vitamin D levels in leprosy patients from North Indian population

PLoS Neglected Tropical Diseases News - 27 November 2018 - 10:00pm

by Itu Singh, Mallika Lavania, Vinay Kumar Pathak, Madhvi Ahuja, Ravindra P. Turankar, Vikram Singh, Utpal Sengupta

Background

Leprosy is a chronic infectious disease caused by Mycobacterium leprae and mainly affects skin, peripheral nerves. Vitamin D receptor (VDR) gene polymorphism has been found to be associated with leprosy. Vitamin D has been shown to control several host immunomodulating properties through VDR gene. Vitamin D deficiency was also found to be linked to an increased risk for several infections and metabolic diseases.

Objective

In the present study, we investigated the association of VDR gene polymorphism, mRNA gene expression of VDR and the vitamin D levels with leprosy and its reactional states.

Methodology

A total of 305 leprosy patients consisting of tuberculoid (TT), borderline tuberculoid (BT), borderline lepromatous (BL), lepromatous leprosy (LL), as well as 200 healthy controls were enrolled in the study. We identified single nucleotide polymorphisms (SNPs) of VDR Taq1, Fok1 and Apa1, as well as the expression of VDR mRNA gene using PCR-based restriction fragment length polymorphism (RFLP) analysis and real-time PCR respectively. We also performed ELISA to measure vitamin D levels.

Result

We observed that SNP of VDR gene (Fok1 and Taq1) are associated with the leprosy disease. The allelic frequency distribution of T and t allele (p = 0.0037), F and f allele (p = 0.0024) was significantly higher in leprosy patients and healthy controls. ff genotype of Fok1 was found to be associated with leprosy patients [p = 0.0004; OR (95% CI) 3.148 (1.662–5.965)]. The recessive model of Fok1 genotype was also found to be significantly associated in leprosy patients in comparison to healthy controls [p = 0.00004; OR (95% CI) 2.85 (1.56–5.22)]. Leprosy patients are significantly associated with t-F-a haplotype. Further, VDR gene expression was found to be lower in non-reaction group compared to that of reaction group of leprosy and healthy controls. Paradoxically, we noted no difference in the levels of vitamin D between leprosy patients and healthy controls.

Conclusion

Blood levels of vitamin D do not play any role in clinical manifestations of any forms of leprosy. ff genotype of Fok1 and tt genotype of Taq1 was found to be associated with leprosy per se. Association of t-F-a haplotype with leprosy was found to be significant and could be used as a genetic marker to identify individuals at high risk for developing leprosy. VDR gene expression was lower in TT/BT and BL/LL groups of leprosy in comparison to that of healthy controls.

Insights into antitrypanosomal drug mode-of-action from cytology-based profiling

PLoS Neglected Tropical Diseases News - 26 November 2018 - 10:00pm

by James Thomas, Nicola Baker, Sebastian Hutchinson, Caia Dominicus, Anna Trenaman, Lucy Glover, Sam Alsford, David Horn

Chemotherapy continues to have a major impact on reducing the burden of disease caused by trypanosomatids. Unfortunately though, the mode-of-action (MoA) of antitrypanosomal drugs typically remains unclear or only partially characterised. This is the case for four of five current drugs used to treat Human African Trypanosomiasis (HAT); eflornithine is a specific inhibitor of ornithine decarboxylase. Here, we used a panel of T. brucei cellular assays to probe the MoA of the current HAT drugs. The assays included DNA-staining followed by microscopy and quantitative image analysis, or flow cytometry; terminal dUTP nick end labelling to monitor mitochondrial (kinetoplast) DNA replication; antibody-based detection of sites of nuclear DNA damage; and fluorescent dye-staining of mitochondria or lysosomes. We found that melarsoprol inhibited mitosis; nifurtimox reduced mitochondrial protein abundance; pentamidine triggered progressive loss of kinetoplast DNA and disruption of mitochondrial membrane potential; and suramin inhibited cytokinesis. Thus, current antitrypanosomal drugs perturb distinct and specific cellular compartments, structures or cell cycle phases. Further exploiting the findings, we show that putative mitogen-activated protein-kinases contribute to the melarsoprol-induced mitotic defect, reminiscent of the mitotic arrest associated signalling cascade triggered by arsenicals in mammalian cells, used to treat leukaemia. Thus, cytology-based profiling can rapidly yield novel insight into antitrypanosomal drug MoA.

Identification and binding mode of a novel <i>Leishmania</i> Trypanothione reductase inhibitor from high throughput screening

PLoS Neglected Tropical Diseases News - 26 November 2018 - 10:00pm

by Lorenzo Turcano, Esther Torrente, Antonino Missineo, Matteo Andreini, Marina Gramiccia, Trentina Di Muccio, Ilaria Genovese, Annarita Fiorillo, Steven Harper, Alberto Bresciani, Gianni Colotti, Andrea Ilari

Trypanothione reductase (TR) is considered to be one of the best targets to find new drugs against Leishmaniasis. This enzyme is fundamental for parasite survival in the host since it reduces trypanothione, a molecule used by the tryparedoxin/tryparedoxin peroxidase system of Leishmania to neutralize hydrogen peroxide produced by host macrophages during infection. In order to identify new lead compounds against Leishmania we developed and validated a new luminescence-based high-throughput screening (HTS) assay that allowed us to screen a library of 120,000 compounds. We identified a novel chemical class of TR inhibitors, able to kill parasites with an IC50 in the low micromolar range. The X-ray crystal structure of TR in complex with a compound from this class (compound 3) allowed the identification of its binding site in a pocket at the entrance of the NADPH binding site. Since the binding site of compound 3 identified by the X-ray structure is unique, and is not present in human homologs such as glutathione reductase (hGR), it represents a new target for drug discovery efforts.

Anilinoquinoline based inhibitors of trypanosomatid proliferation

PLoS Neglected Tropical Diseases News - 26 November 2018 - 10:00pm

by Lori Ferrins, Amrita Sharma, Sarah M. Thomas, Naimee Mehta, Jessey Erath, Scott Tanghe, Susan E. Leed, Ana Rodriguez, Kojo Mensa-Wilmot, Richard J. Sciotti, Kirsten Gillingwater, Michael P. Pollastri

We recently reported the medicinal chemistry re-optimization of a series of compounds derived from the human tyrosine kinase inhibitor, lapatinib, for activity against Plasmodium falciparum. From this same library of compounds, we now report potent compounds against Trypanosoma brucei brucei (which causes human African trypanosomiasis), T. cruzi (the pathogen that causes Chagas disease), and Leishmania spp. (which cause leishmaniasis). In addition, sub-micromolar compounds were identified that inhibit proliferation of the parasites that cause African animal trypanosomiasis, T. congolense and T. vivax. We have found that this set of compounds display acceptable physicochemical properties and represent progress towards identification of lead compounds to combat several neglected tropical diseases.

Aerosol exposure to intermediate size Nipah virus particles induces neurological disease in African green monkeys

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Dima A. Hammoud, Margaret R. Lentz, Abigail Lara, Jordan K. Bohannon, Irwin Feuerstein, Louis Huzella, Peter B. Jahrling, Matthew Lackemeyer, Joseph Laux, Oscar Rojas, Philip Sayre, Jeffrey Solomon, Yu Cong, Vincent Munster, Michael R. Holbrook

Nipah virus (NiV) infection can lead to severe respiratory or neurological disease in humans. Transmission of NiV has been shown to occur through contact with virus contaminated fomites or consumption of contaminated food. Previous results using the African green monkey (AGM) model of NiV infection identified aspects of infection that, while similar to humans, don’t fully recapitulate disease. Previous studies also demonstrate near uniform lethality that is not consistent with human NiV infection. In these studies, aerosol exposure using an intermediate particle size (7μm) was used to mimic potential human exposure by facilitating virus deposition in the upper respiratory tract. Computed tomography evaluation found some animals developed pulmonary parenchymal disease including consolidations, ground-glass opacities, and reactive adenopathy. Despite the lack of neurological signs, magnetic resonance imaging identified distinct brain lesions in three animals, similar to those previously reported in NiV-infected patients. Immunological characterization of tissues collected at necropsy suggested a local pulmonary inflammatory response with increased levels of macrophages in the lung, but a limited neurologic response. These data provide the first clear evidence of neurological involvement in the AGM that recapitulates human disease. With the development of a disease model that is more representative of human disease, these data suggest that NiV infection in the AGM may be appropriate for evaluating therapeutic countermeasures directed at virus-induced neuropathogenesis.

Backpack PCR: A point-of-collection diagnostic platform for the rapid detection of Brugia parasites in mosquitoes

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Weam I. Zaky, Francesca R. Tomaino, Nils Pilotte, Sandra J. Laney, Steven A. Williams

Background

Currently, molecular xenomonitoring efforts for lymphatic filariasis rely on PCR or real-time PCR-based detection of Brugia malayi, Brugia timori and Wuchereria bancrofti in mosquito vectors. Most commonly, extraction of DNA from mosquitoes is performed using silica column-based technologies. However, such extractions are both time consuming and costly, and the diagnostic testing which follows typically requires expensive thermal cyclers or real-time PCR instruments. These expenses present significant challenges for laboratories in many endemic areas. Accordingly, in such locations, there exists a need for inexpensive, equipment-minimizing diagnostic options that can be transported to the field and implemented in minimal resource settings. Here we present a novel diagnostic approach for molecular xenomonitoring of filarial parasites in mosquitoes that uses a rapid, NaOH-based DNA extraction methodology coupled with a portable, battery powered PCR platform and a test strip-based DNA detection assay. While the research reported here serves as a proof-of-concept for the backpack PCR methodology for the detection of filarial parasites in mosquitoes, the platform should be easily adaptable to the detection of W. bancrofti and other mosquito-transmitted pathogens.

Methodology/Principal findings

Through comparisons with standard silica column-based DNA extraction techniques, we evaluated the performance of a rapid, NaOH-based methodology for the extraction of total DNA from pools of parasite-spiked vector mosquitoes. We also compared our novel test strip-based detection assay to real-time PCR and conventional PCR coupled with gel electrophoresis, and demonstrated that this method provides sensitive and genus-specific detection of parasite DNA from extracted mosquito pools. Finally, by comparing laboratory-based thermal cycling with a field-friendly miniaturized PCR approach, we have demonstrated the potential for the point-of-collection-based use of this entire diagnostic platform that is compact enough to fit into a small backpack.

Conclusions/Significance

Because this point-of-collection diagnostic platform eliminates reliance on expensive and bulky instrumentation without compromising sensitivity or specificity of detection, it provides an alternative to cost-prohibitive column-dependent DNA extractions that are typically coupled to detection methodologies requiring advanced laboratory infrastructure. In doing so, this field-ready system should increase the feasibility of molecular xenomonitoring within B. malayi-endemic locations. Of greater importance, this backpack PCR system also provides the proof-of-concept framework for the development of a parallel assay for the detection of W. bancrofti.

Organization of oversight for integrated control of neglected tropical diseases within Ministries of Health

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Claire Standley, Matthew R. Boyce, Anna Klineberg, Gabrielle Essix, Rebecca Katz

Background

Neglected tropical diseases (NTDs) are communicable diseases that impact approximately 1 billion people, but receive relatively little research, funding, and attention. Many NTDs have similar treatments, epidemiology, and geographic distribution, and as a result, the integration of control efforts can improve accountability, efficiency, and cost-effectiveness of programs. Here, we examine the landscape of efforts towards NTD integration across countries with the highest burden of disease, and review the administrative management of integration in order to identify approaches and pathways for integration.

Methodology and principal findings

We utilized a standardized system to score countries for NTD endemnicity to create a list of 25 countries with the highest overall burden of NTDs. We then conducted a literature review to characterize the NTD control programs in the focus countries. Six countries were selected for key informant interviews to validate literature review results and gather additional data on opportunities and obstacles to NTD integration, from an administrative perspective. The majority of countries included in the study were located in Africa, with the remainder from Asia, North America, and South America. Multiple models and pathways were observed for the integration of NTD programs, in combination with other NTD programs, other diseases, or other health programs. Substantial heterogeneity existed with respect to the NTD control programs, and no country had integrated all of their NTD control efforts into a single program. NTDs that can be treated with preventative chemotherapy were frequently integrated into a single program. Leprosy control was also frequently integrated with those of other communicable diseases, and notably tuberculosis. Barriers to NTD integration may result from internal administrative obstacles or external obstacles.

Conclusions

Although many countries have begun to integrate NTD control efforts, additional work will be required to realize the full benefits of integration in most of the countries examined here. Moving forward, NTD integration efforts must ensure that administrative structures are designed to maximize the potential success of integrated programs and account for existing administrative processes.

EAPB0503: An Imiquimod analog with potent <i>in vitro</i> activity against cutaneous leishmaniasis caused by <i>Leishmania major</i> and <i>Leishmania tropica</i>

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Rana El Hajj, Hanady Bou Youness, Laurence Lachaud, Patrick Bastien, Carine Masquefa, Pierre-Antoine Bonnet, Hiba El Hajj, Ibrahim Khalifeh

Cutaneous Leishmaniasis (CL) is a parasitic infection classified by the WHO as one of the most uncontrolled spreading neglected diseases. Syria is endemic for Leishmania tropica and Leishmania major, causing CL in the Eastern Mediterranean. The large-scale displacement of Syrian refugees exacerbated the spread of CL into neighboring countries. Therapeutic interventions against CL include local, systemic and physical treatments. The high risk for drug-resistance to current treatments stresses the need for new therapies. Imiquimod is an immunomodulatory drug with a tested efficacy against L. major species. Yet, Imiquimod efficacy against L. tropica and the molecular mechanisms dictating its potency are still underexplored. In this study, we characterized the effect of Imiquimod against L. tropica and L. major, and characterized the molecular mechanisms dictating its anti-leishmanial efficacy against both strains. We also investigated the potency and molecular mechanisms of an Imiquimod analog, EAPB0503, against these two strains. We have tested the effect of Imiquimod and EAPB0503 on macrophages infected with either L. major, L. tropica strains, or patient-derived freshly isolated L. tropica parasites. The anti-amastigote activity of either drugs was assessed by quantitative real time PCR (RT-PCR) using kinetoplast specific primers, confocal microscopy using the Glycoprotein 63 (Gp63) Leishmania amastigote antibody or by histology staining. The mechanism of action of either drugs on the canonical nuclear factor kappa- B (NF-κB) pathway was determined by western blot, and confocal microscopy. The immune production of cytokines upon treatment of infected macrophages with either drugs was assessed by ELISA. Both drugs reduced amastigote replication. EAPB0503 proved more potent, particularly on the wild type L. tropica amastigotes. Toll-Like Receptor-7 was upregulated, mainly by Imiquimod, and to a lesser extent by EAPB0503. Both drugs activated the NF-κB canonical pathway triggering an immune response and i-NOS upregulation in infected macrophages. Our findings establish Imiquimod as a strong candidate for treating L. tropica and show the higher potency of its analog EAPB0503 against CL.

Epidemiology of dengue and other arboviruses in a cohort of school children and their families in Yucatan, Mexico: Baseline and first year follow-up

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Diana Patricia Rojas, Gloria Abigail Barrera-Fuentes, Norma Pavia-Ruz, Mariel Salgado-Rodriguez, Azael Che-Mendoza, Pablo Manrique-Saide, Gonzalo M. Vazquez-Prokopec, M. Elizabeth Halloran, Ira M. Longini, Hector Gomez-Dantes

Dengue is the most prevalent mosquito-borne viral disease of humans and is caused by the four serotypes of dengue virus. To estimate the incidence of dengue and other arboviruses, we analyzed the baseline and first year follow-up of a prospective school-based cohort study and their families in three cities in the state of Yucatan, Mexico. Through enhanced surveillance activities, acute febrile illnesses in the participants were detected and yearly blood samples were collected to evaluate dengue infection incidence. A Cox model was fitted to identify hazard ratios of arboviral infections in the first year of follow-up of the cohort. The incidence of dengue symptomatic infections observed during the first year of follow-up (2015–2016) was 3.5 cases per 1,000 person-years (95% CI: 1.9, 5.9). The incidence of dengue infections was 33.9 infections per 1,000 person-years (95% CI: 31.7, 48.0). The majority of dengue infections and seroconversions were observed in the younger age groups (≤ 14 years old). Other arboviruses were circulating in the state of Yucatan during the study period. The incidence of symptomatic chikungunya infections was 8.6 per 1,000 person-years (95% CI: 5.8, 12.3) and the incidence of symptomatic Zika infections was 2.3 per 1,000 person-years (95% CI: 0.9, 4.5). Our model shows that having a dengue infection during the first year of follow-up was significantly associated with being female, living in Ticul or Progreso, and being dengue naïve at baseline. Age was not significantly associated with the outcome, it was confounded by prior immunity to dengue that increases with age. This is the first report of a cohort in Latin America that provides incidence estimates of the three arboviruses co-circulating in all age groups. This study provides important information for understanding the epidemiology of dengue and other arboviruses and better informing public health policies.

Dengue seroprevalence in a cohort of schoolchildren and their siblings in Yucatan, Mexico (2015-2016)

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Norma Pavía-Ruz, Gloria Abigail Barrera-Fuentes, Salha Villanueva-Jorge, Azael Che-Mendoza, Julio César Campuzano-Rincón, Pablo Manrique-Saide, Diana Patricia Rojas, Gonzalo M. Vazquez-Prokopec, M. Elizabeth Halloran, Ira M. Longini, Héctor Gómez-Dantés

Background

The implementation of vector control interventions and potential introduction new tools requires baseline data to evaluate their direct and indirect effects. The objective of the study is to present the seroprevalence of dengue infection in a cohort of children 0 to 15 years old followed during 2015 to 2016, the risk factors and the role of enhanced surveillance strategies in three urban sites (Merida, Ticul and Progreso) in Yucatan, Mexico.

Methods

A cohort of school children and their family members was randomly selected in three urban areas with different demographic, social conditions and levels of transmission. We included results from 1,844 children aged 0 to 15 years. Serum samples were tested for IgG, NS1 and IgM. Enhanced surveillance strategies were established in schools (absenteeism) and cohort families (toll-free number).

Results

Seroprevalence in children 0 to 15 years old was 46.8 (CI 95% 44.1–49.6) with no difference by sex except in Ticul. Prevalence increased with age and was significantly lower in 0 to 5 years old (26.9%, 95% CI:18.4–35.4) compared with 6 to 8 years old (43.9%, 95% CI:40.1–47.7) and 9 to 15 years old (61.4%, 95% CI:58.0–64.8). Sharing the domestic space with other families increased the risk 1.7 times over the individual families that own or rented their house, while risk was significantly higher when kitchen and bathroom were outside. Complete protection with screens in doors and windows decreased risk of infection. Seroprevalence was significantly higher in the medium and high risk areas.

Conclusions

The prevalence of antibodies in children 0 to 15 years in three urban settings in the state of Yucatan describe the high exposure and the heterogenous transmission of dengue virus by risk areas and between schools in the study sites. The enhanced surveillance strategy was useful to improve detection of dengue cases with the coincident transmission of chikungunya and Zika viruses.

The right to deworming: The case for girls and women of reproductive age

PLoS Neglected Tropical Diseases News - 21 November 2018 - 10:00pm

by Theresa W. Gyorkos, Antonio Montresor, Vicente Belizario, Beverley-Ann Biggs, Mark Bradley, Simon J. Brooker, Martin Casapia, Philip Cooper, Sila Deb, Nicolas L. Gilbert, Rubina Imtiaz, Virak Khieu, Stefanie Knopp, Ornella Lincetto, Layla S. Mofid, Denise Mupfasoni, Cori Vail, Jozef Vercruysse

Modelling the cost-effectiveness of a rapid diagnostic test (IgMFA) for uncomplicated typhoid fever in Cambodia

PLoS Neglected Tropical Diseases News - 19 November 2018 - 10:00pm

by Mari Kajiwara Saito, Christopher M. Parry, Shunmay Yeung

Typhoid fever is a common cause of fever in Cambodian children but diagnosis and treatment are usually presumptive owing to the lack of quick and accurate tests at an initial consultation. This study aimed to evaluate the cost-effectiveness of using a rapid diagnostic test (RDT) for typhoid fever diagnosis, an immunoglobulin M lateral flow assay (IgMFA), in a remote health centre setting in Cambodia from a healthcare provider perspective. A cost-effectiveness analysis (CEA) with decision analytic modelling was conducted. We constructed a decision tree model comparing the IgMFA versus clinical diagnosis in a hypothetical cohort with 1000 children in each arm. The costs included direct medical costs only. The eligibility was children (≤14 years old) with fever. Time horizon was day seven from the initial consultation. The number of treatment success in typhoid fever cases was the primary health outcome. The number of correctly diagnosed typhoid fever cases (true-positives) was the intermediate health outcome. We obtained the incremental cost effectiveness ratio (ICER), expressed as the difference in costs divided by the difference in the number of treatment success between the two arms. Sensitivity analyses were conducted. The IgMFA detected 5.87 more true-positives than the clinical diagnosis (38.45 versus 32.59) per 1000 children and there were 3.61 more treatment successes (46.78 versus 43.17). The incremental cost of the IgMFA was estimated at $5700; therefore, the ICER to have one additional treatment success was estimated to be $1579. The key drivers for the ICER were the relative sensitivity of IgMFA versus clinical diagnosis, the cost of IgMFA, and the prevalence of typhoid fever or multi-drug resistant strains. The IgMFA was more costly but more effective than the clinical diagnosis in the base-case analysis. An IgMFA could be more cost-effective than the base-case if the sensitivity of IgMFA was higher or cost lower. Decision makers may use a willingness-to-pay threshold that considers the additional cost of hospitalisation for treatment failures.

Vertical transmission of naturally occurring Bunyamwera and insect-specific flavivirus infections in mosquitoes from islands and mainland shores of Lakes Victoria and Baringo in Kenya

PLoS Neglected Tropical Diseases News - 19 November 2018 - 10:00pm

by Yvonne Ukamaka Ajamma, Thomas Ogao Onchuru, Daniel O. Ouso, David Omondi, Daniel K. Masiga, Jandouwe Villinger

Background

Many arboviruses transmitted by mosquitoes have been implicated as causative agents of both human and animal illnesses in East Africa. Although epidemics of arboviral emerging infectious diseases have risen in frequency in recent years, the extent to which mosquitoes maintain pathogens in circulation during inter-epidemic periods is still poorly understood. This study aimed to investigate whether arboviruses may be maintained by vertical transmission via immature life stages of different mosquito vector species.

Methodology

We collected immature mosquitoes (egg, larva, pupa) on the shores and islands of Lake Baringo and Lake Victoria in western Kenya and reared them to adults. Mosquito pools (≤25 specimens/pool) of each species were screened for mosquito-borne viruses by high-resolution melting analysis and sequencing of multiplex PCR products of genus-specific primers (alphaviruses, flaviviruses, phleboviruses and Bunyamwera-group orthobunyaviruses). We further confirmed positive samples by culturing in baby hamster kidney and Aedes mosquito cell lines and re-sequencing.

Principal findings

Culex univittatus (2/31pools) and Anopheles gambiae (1/77 pools) from the Lake Victoria region were positive for Bunyamwera virus, a pathogenic virus that is of public health concern. In addition, Aedes aegypti (3/50), Aedes luteocephalus (3/13), Aedes spp. (2/15), and Culex pipiens (1/140) pools were positive for Aedes flaviviruses at Lake Victoria, whereas at Lake Baringo, three pools of An. gambiae mosquitoes were positive for Anopheles flavivirus. These insect-specific flaviviruses (ISFVs), which are presumably non-pathogenic to vertebrates, were found in known medically important arbovirus and malaria vectors.

Conclusions

Our results suggest that not only ISFVs, but also a pathogenic arbovirus, are naturally maintained within mosquito populations by vertical transmission, even in the absence of vertebrate hosts. Therefore, virus and vector surveillance, even during inter-epidemics, and the study of vector-arbovirus-ISFV interactions, may aid in identifying arbovirus transmission risks, with the potential to inform control strategies that lead to disease prevention.

Antivirus effectiveness of ivermectin on dengue virus type 2 in <i>Aedes albopictus</i>

PLoS Neglected Tropical Diseases News - 19 November 2018 - 10:00pm

by Tie-Long Xu, Yin Han, Wei Liu, Xing-Ya Pang, Bin Zheng, Yi Zhang, Xiao-Nong Zhou

Background

Dengue fever is the most rapidly spreading mosquito-borne viral disease over the past 50 years, with a 30-fold increase in global incidence. Dengue vector control is a key component for the dengue control strategy, since no absolutely effective vaccine or drug is available yet. However, the rapid rise and spread of mosquito insecticide resistance have become major threats to the efficiency of insecticide-based vector control activities. Thus, innovative vector control tools are badly needed. This study aims to confirm the antivirus effectiveness of ivermectin on dengue virus type 2 (DENV-2) in Aedes albopictus (Skuse, 1894), then to explore its potential use in the combating to the dengue epidemics.

Methods

Aedes albopictus were first infected with DENV-2 in human whole blood, and at the fourth day after infectious blood feeding, they were divided into eight groups. Seven of them were held for six days with access to 0, 2, 4, 8, 16, 32 and 64 ng/ml ivermectin, respectively, and the last one was set as a historical control group, which was stored at -80°C until being detected at the same time with the other groups. Each mosquito was detected using real-time fluorescent RT-PCR kit. DENV-2 RNA concentration (copies/ml) and infection rate in each group were compared.

Results

Both of quantitatively and qualitatively inhibiting effects of ivermectin have been detected in this study. Generally, DENV-2 replicated well in Aedes albopictus without ivermectin intervention, whose virus loads exhibited significantly higher when the mosquitoes were holding from 4 days to 10 days after infectious blood feeding. In contrast, with the treatment of ivermectin, the infection rate was reduced by as much as 49.63%. The regression equation between infection rates (Y2) and ivermectin concentration log2 values (X2) was obtained as Y2 = 91.41–7.21*X2 with R2 = 0.89.

Conclusion

Ivermectin can directly or indirectly inhibit DENV-2 multiplication in Aedes albopictus. Moreover, the actual concentration for application in zooprophylaxis needs to be confirmed in the further field trials.

CYP-mediated permethrin resistance in <i>Aedes aegypti</i> and evidence for <i>trans</i>-regulation

PLoS Neglected Tropical Diseases News - 19 November 2018 - 10:00pm

by Letícia B. Smith, Rakshit Tyagi, Shinji Kasai, Jeffrey G. Scott

Aedes aegypti poses a serious risk to human health due to its wide global distribution, high vector competence for several arboviruses, frequent human biting, and ability to thrive in urban environments. Pyrethroid insecticides remain the primary means of controlling adult A. aegypti populations during disease outbreaks. As a result of decades of use, pyrethroid resistance is a global problem. Cytochrome P450 monooxygenase (CYP)-mediated detoxification is one of the primary mechanisms of pyrethroid resistance. However, the specific CYP(s) responsible for resistance have not been unequivocally determined. We introgressed the resistance alleles from the resistant A. aegypti strain, Singapore (SP), into the genetic background of the susceptible ROCK strain. The resulting strain (CKR) was congenic to ROCK. Our primary goal was to determine which CYPs in SP are linked to resistance. To do this, we first determined which CYPs overexpressed in SP are also overexpressed in CKR, with the assumption that only the CYPs linked to resistance will be overexpressed in CKR relative to ROCK. Next, we determined whether any of the overexpressed CYP(s) were genetically linked to resistance (cis-regulated) or not (trans-regulated). We found that CYP6BB2, CYP6Z8, CYP9M5 and CYP9M6 were overexpressed in SP as well as in CKR. Based on the genomic sequences and polymorphisms in each strain, none of these genes were linked to resistance, except for CYP6BB2, which was partially linked to the resistance locus. Hence, overexpression of these four CYPs is due to a trans-regulatory factor(s). Knowledge on the specific CYPs and their regulators involved in resistance is critical for resistance management strategies because it aids in the development of new control chemicals, provides information on potential environmental modulators of resistance, and allows for the detection of resistance markers before resistance becomes fixed in the population.

Identification and characterization of <i>Loa loa</i> antigens responsible for cross-reactivity with rapid diagnostic tests for lymphatic filariasis

PLoS Neglected Tropical Diseases News - 16 November 2018 - 10:00pm

by Marla I. Hertz, Hugues Nana-Djeunga, Joseph Kamgno, Abdel Jelil Njouendou, Valerine Chawa Chunda, Samuel Wanji, Amy Rush, Peter U. Fischer, Gary J. Weil, Philip J. Budge

The Global Program to Eliminate Lymphatic Filariasis (LF) relies on rapid diagnostic tests (RDTs) to determine where annual mass drug administration for LF is required and when it can be stopped. These tests detect a Wuchereria bancrofti glycoprotein in the blood of infected persons via a carbohydrate moiety recognized by the monoclonal antibodies AD12 and DH6.5. Loiasis cross-reactivity with LF RDTs has recently been recognized as a serious obstacle to LF elimination in loiasis-endemic areas. To better understand the nature of this cross-reactivity, we used the DH6.5 antibody to immunoaffinity purify Loa loa antigens from the sera of individuals with a positive RDT due to loiasis. Immunoblot analysis revealed many circulating AD12/DH6.5-reactive antigens, and proteomic analysis identified multiple L. loa proteins in LF RDT-positive loiasis sera. These included both secreted and somatic proteins, suggesting that they may be released by dying L. loa adult worms and/or microfilariae. Unlike the single high molecular weight W. bancrofti circulating filarial antigen that is reliably present in the blood of persons with bancroftian filariasis, reactive L. loa antigens appeared to be only transiently present in the blood of a subset of persons with loiasis. These key differences between the circulating antigens of W. bancrofti and L. loa can be used to differentiate positive results generated by both species and may lead to improved diagnostic tests for LF and loiasis.

Liver ultrasound elastography for the evaluation of periportal fibrosis in schistosomiasis mansoni: A cross-sectional study

PLoS Neglected Tropical Diseases News - 16 November 2018 - 10:00pm

by Joelma Carvalho Santos, Andrea Dória Batista, Carla Maria Mola Vasconcelos, Roberto Souza Lemos, Valter Romão de Souza Junior, Alain Dessein, Hélia Dessein, Silvia Maria Lucena Montenegro, Edmundo Pessoa Almeida Lopes, Ana Lúcia Coutinho Domingues

Background

ARFI elastrography has been used as a noninvasive method to assess the severity of liver fibrosis in viral hepatitis, although with few studies in schistosomiasis mansoni. We aimed to evaluate the performance of point shear wave elastography (pSWE) for predicting significant periportal fibrosis (PPF) in schistosomotic patients and to determine its best cutoff point.

Methodology/principal findings

This cross-sectional study included 358 adult schistosomotic patients subjected to US and pSWE on the right lobe. Two hundred two patients (62.0%) were women, with a median age of 54 (ranging 18–92) years. The pSWE measurements were compared to the US patterns of PPF, as gold standard, according to the Niamey classification. The performance of pSWE was calculated as the area under the ROC curve (AUC). Patients were further classified into two groups: 86 patients with mild PPF and 272 patients with significant PPF. The median pSWE of the significant fibrosis group was higher (1.40 m/s) than that of mild fibrosis group (1.14 m/s, p<0.001). AUC was 0.719 with ≤1.11 m/s as the best cutoff value for excluding significant PPF. Sensitivity and negative predictive values were 80.5% and 40.5%, respectively. Whereas, for confirming significant PPF, the best cutoff value was >1.39 m/s, with specificity of 86.1% and positive predictive value of 92.0%.

Conclusions/significance

pSWE was able to differentiate significant from mild PPF, with better performance to predict significant PPF.

Prevalence and distribution of <i>Taenia solium</i> cysticercosis in naturally infected pigs in Punjab, India

PLoS Neglected Tropical Diseases News - 15 November 2018 - 10:00pm

by Satinder Pal Singh, Balbir Bagicha Singh, Deepali G. Kalambhe, Devendra Pathak, Rabinder Singh Aulakh, Navneet K. Dhand

Background

Taenia solium (T. solium) cysticercosis remains a neglected zoonotic disease in India. The current study was planned to estimate the prevalence of T. solium porcine cysticercosis in the Punjab state of India, to compare this prevalence with the disease prevalence in pigs reared outside Punjab and to assess the distribution of the parasite in pig carcasses.

Methods

Two slaughter shops were selected in each of the 22 districts of Punjab. Pigs slaughtered on the day/s of inspection were post-mortem inspected to identify the presence of T. solium cysts. Estimated true prevalence was estimated by taking into account the diagnostic sensitivity (38%) and specificity (100%) of post-mortem inspection using the Rogan-Gladen estimator. Positive carcasses were purchased and brought to the laboratory to assess the tissue distribution of T. solium cysts and to conduct PCR targeting large subunit rRNA gene, internal transcribed spacer 1 gene, ITS1 gene and Cytochrome oxidase I gene. The selected PCR products were submitted for sequencing and phylogenetic analyses were performed.

Findings

We contacted 71 shop owners to achieve a sample of 44 shops for the study. We inspected 642 pigs reared in Punjab and 450 imported from other states at these slaughter shops. In addition, we sampled 40 pigs from an abattoir located in the state capital. Of the 642 pigs reared in Punjab, 9 had T. solium cysts with an apparent prevalence of 1·40% (95% CI: 0·74%, 2·64%) and the estimated true prevalence of 3.69% (95% CI: 1·95%, 6·95%). Pigs imported from outside the state had a significantly higher prevalence (odds ratio: 2·58; 95% CI: 1·12, 5·98; p-value: 0·026) as 15 of the 450 imported pigs were positive (apparent prevalence: 3.33%; 95% CI: 2.03%, 5.43%; estimated true prevalence: 8.77%; 95% CI: 5.34%, 14.28%). None of samples was positive from the pigs sampled at the abattoir in the state capital. The PCR confirmed T. solium cysts from all the 24 positive samples. We counted a median of 897 (range 526–1964) cysts per infected pig from the 19 infected pig carcasses inspected. The phylogenetic tree based on the alignment of partial cytochrome oxidase 1 sequences indicated all positive samples to be clustered with the T. solium Asian genotype. The analysis did not indicate the presence of T. asiatica in the slaughter pigs.

Conclusions

Despite the underestimation of the prevalence due to missing mildly-infected carcasses, low participation and lack of representative sampling, the presence of heavily infected carcasses containing viable cysts, particularly those imported from outside the state, indicates that T. solium cysticercosis is an important food safety concern for pork consumers in Punjab, India. Measures should be taken to reduce the disease prevalence in pigs to reduce the disease burden in the public.

Accuracy of the WHO praziquantel dose pole for large-scale community treatment of urogenital schistosomiasis in northern Mozambique: Is it time for an update?

PLoS Neglected Tropical Diseases News - 15 November 2018 - 10:00pm

by Pedro H. Gazzinelli-Guimaraes, Neerav Dhanani, Charles H. King, Carl H. Campbell, Herminio O. Aurelio, Josefo Ferro, Rassul Nala, Alan Fenwick, Anna E. Phillips

Background

A pioneering strategy developed by the World Health Organization (WHO) for the control of schistosomiasis was the concept of a height-based dose pole to determine praziquantel (PZQ) dosing in large-scale treatment campaigns. However, some recent studies have shown variable accuracy for the dose pole in terms of predicting correct mg/Kg dosing, particularly for treatment of adults. According to the WHO, 91 million adults in 52 countries are targeted to be treated by 2020.

Methods/Principal findings

The present study aimed to test the accuracy of the dose pole in determining PZQ dosage by comparing the number of tablets determined by the dose pole with the number of tablets determined according to total body weight. The analysis included height-for-weight data from 9,827 school-aged children (SAC) and adults from 42 villages in the province of Cabo Delgado in Mozambique. The results revealed that of the 7,596 SAC, 91.8% has received an appropriate dose (30-60mg/Kg), 6% received an insufficient dose (<30mg/Kg) and 2% an excessive dose (> 60mg/Kg). On the other hand, 13.7% out of 2,231 adults were treated inaccurately with 13.5% receiving an insufficient dose. When the percentage of insufficient dosing was disaggregated by gender, the frequency of adult females who were underdosed reached 18.3% versus 10.8% of adult males. Adult females aged 21–55 years were found to have an underdose frequency of 21.3%, compared to 11.8% of adult males in the same age range. The performance of a proposed modified dose pole was compared using the same dataset of adult Mozambicans. The results showed that the modified dose pole reduced the underdose frequency among adults from 13.5% to 10.4%, and subsequently increasing the percentage of optimal dosing from 33.7% to 45.3%.

Conclusions

Our findings highlight the need to update the WHO-dose pole to avoid administration of insufficient PZQ doses to adults and therefore minimize the potential emergence of PZQ-resistant strains.

Trial registration

International Standard Randomized Controlled Trial registry under ISRTC number 14117624

Geostatistical mapping of the seasonal spread of under-reported dengue cases in Bangladesh

PLoS Neglected Tropical Diseases News - 15 November 2018 - 10:00pm

by Sifat Sharmin, Kathryn Glass, Elvina Viennet, David Harley

Geographical mapping of dengue in resource-limited settings is crucial for targeting control interventions but is challenging due to the problem of zero-inflation because many cases are not reported. We developed a negative binomial generalised linear mixed effect model accounting for zero-inflation, spatial, and temporal random effects to investigate the spatial variation in monthly dengue cases in Bangladesh. The model was fitted to the district-level (64 districts) monthly reported dengue cases aggregated over the period 2000 to 2009 and Bayesian inference was performed using the integrated nested Laplace approximation. We found that mean monthly temperature and its interaction with mean monthly diurnal temperature range, lagged by two months were significantly associated with dengue incidence. Mean monthly rainfall at two months lag was positively associated with dengue incidence. Densely populated districts and districts bordering India or Myanmar had higher incidence than others. The model estimated that 92% of the annual dengue cases occurred between August and September. Cases were identified across the country with 94% in the capital Dhaka (located almost in the middle of the country). Less than half of the affected districts reported cases as observed from the surveillance data. The proportion reported varied by month with a higher proportion reported in high-incidence districts, but dropped towards the end of high transmission season.

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