RSS news feeds

Flubendazole as a macrofilaricide: History and background

PLoS Neglected Tropical Diseases News - 16 January 2019 - 10:00pm

by Timothy G. Geary, Charles D. Mackenzie, Steven A. Silber

Benzimidazole anthelmintics have long been employed for the control of soil-transmitted helminth infections. Flubendazole (FBZ) was approved in 1980 for the treatment of gastrointestinal nematode infections in both veterinary and human medicine. It has also long been known that parenteral administration of FBZ can lead to high macrofilaricidal efficacy in a variety of preclinical models and in humans. As part of an effort to stimulate the discovery and development of new macrofilaricides, particularly for onchocerciasis, research has recently been devoted to the development of new formulations that would afford high oral bioavailability of FBZ, paving the way for potential clinical development of this repurposed drug for the treatment of human filariases. This review summarizes the background information that led to this program and summarizes some of the lessons learned from it.

Short-course, oral flubendazole does not mediate significant efficacy against <i>Onchocerca</i> adult male worms or <i>Brugia</i> microfilariae in murine infection models

PLoS Neglected Tropical Diseases News - 16 January 2019 - 10:00pm

by Hanna T. Sjoberg, Nicolas Pionnier, Ghaith Aljayyoussi, Haelly M. Metuge, Abdel J. Njouendou, Valerine C. Chunda, Fanny F. Fombad, Dizzle B. Tayong, Narcisse V. T. Gandjui, Desmond N. Akumtoh, Patrick W. N. Chounna, Bertrand L. Ndzeshang, Sophie Lachaud, Fetene Tekle, Ludo Quirynen, Marc Engelen, Benny Baeten, Andrew Steven, Stephen A. Ward, Mark J. Taylor, Samuel Wanji, Joseph D. Turner

The Onchocerca ochengi adult implant and Brugia malayi microfilariemic Severe-Combined Immunodeficient (SCID) mouse models are validated screens to measure macrofilaricidal and microfilaricidal activities of candidate onchocerciasis drugs. The purpose of this study was to assess whether 5 daily sub-cutaneous (s.c.) injections of standard flubendazole (FBZ) suspension (10mg/kg), a single s.c. injection (10mg/kg) or 5 daily repeated oral doses of FBZ amorphous solid dispersion (ASD) formulation (0.2, 1.5 or 15mg/kg) mediated macrofilaricidal efficacy against O. ochengi male worms implanted into SCID mice. The direct microfilaricidal activity against circulating B. malayi microfilariae of single dose FBZ ASD formulation (2 or 40 mg/kg) was also evaluated and compared against the standard microfilaricide, ivermectin (IVM). Systemic exposures of FBZ/FBZ metabolites achieved following dosing were measured by pharmacokinetic (PK) bioanalysis. At necropsy, five weeks following start of FBZ SC injections, there were significant reductions in burdens of motile O. ochengi worms following multiple injections (93%) or single injection (82%). Further, significant proportions of mice dosed following multiple injections (5/6; 83%) or single injection (6/10; 60%) were infection negative (drug-cured). In comparison, no significant reduction in recovery of motile adult O. ochengi adult worms was obtained in any multiple-oral dosage group. Single oral-dosed FBZ did not mediate any significant microfilaricidal activity against circulating B. malayi mf at 2 or 7 days compared with >80% efficacy of single dose IVM. In conclusion, multiple oral FBZ formulation doses, whilst achieving substantial bioavailability, do not emulate the efficacy delivered by the parenteral route in vivo against adult O. ochengi. PK analysis determined FBZ efficacy was related to sustained systemic drug levels rather than achievable Cmax. PK modelling predicted that oral FBZ would have to be given at low dose for up to 5 weeks in the mouse model to achieve a matching efficacious exposure profile.

Macrofilaricidal efficacy of single and repeated oral and subcutaneous doses of flubendazole in <i>Litomosoides sigmodontis</i> infected jirds

PLoS Neglected Tropical Diseases News - 16 January 2019 - 10:00pm

by Marc P. Hübner, Alexandra Ehrens, Marianne Koschel, Bettina Dubben, Franziska Lenz, Stefan J. Frohberger, Sabine Specht, Ludo Quirynen, Sophie Lachau-Durand, Fetene Tekle, Benny Baeten, Marc Engelen, Charles D. Mackenzie, Achim Hoerauf

Flubendazole (FBZ) is highly efficacious against filarial nematodes after parenteral administration and presents a promising macrofilaricidal drug candidate for the elimination of onchocerciasis and other filariae. In the present study the efficacy of a newly developed bioavailable amorphous solid dispersion (ASD) oral formulation of FBZ was investigated in the Litomosoides sigmodontis jird model. FBZ was administered to chronically infected, microfilariae-positive jirds by single (40mg/kg), repeated (2, 6 or 15mg/kg for 5 or 10 days) oral (OR) doses or single subcutaneous (SC) injections (2 or 10mg/kg). Jirds treated with 5 SC injections at 10mg/kg served as positive controls, with untreated animals used as negative controls. After OR doses, FBZ is rapidly absorbed and cleared and the exposures increased dose proportionally. SC administered FBZ was slowly released from the injection site and plasma levels remained constant up to necropsy eight weeks after treatment end. Increasing single SC doses caused less than dose-proportional exposures. At necropsy, all animals receiving 1x or 5x 10mg/kg SC FBZ had cleared all adult worms and the 1x 2mg/kg SC treatment had reduced the adult worm burden by 98%. 10x 15mg/kg OR FBZ reduced the adult worm burden by 95%, whereas 1x 40mg/kg and 5x 15mg/kg OR reduced the worm burden by 85 and 84%, respectively. Microfilaremia was completely cleared at necropsy in all animals of the SC treatment regimens, while all oral FBZ treatment regimens reduced the microfilaremia by >90% in a dose and duration dependent manner. In accordance, embryograms from female worms revealed a FBZ dose and duration dependent inhibition of embryogenesis. Histological analysis of the remaining female adult worms showed that FBZ had damaged the body wall, intestine and most prominently the uterus and uterine content. Results of this study demonstrate that single and repeated SC injections and repeated oral administrations of FBZ have an excellent macrofilaricidal effect.

Utilization of proliferable extracellular amastigotes for transient gene expression, drug sensitivity assay, and CRISPR/Cas9-mediated gene knockout in <i>Trypanosoma cruzi</i>

PLoS Neglected Tropical Diseases News - 14 January 2019 - 10:00pm

by Yuko Takagi, Yukie Akutsu, Motomichi Doi, Koji Furukawa

Trypanosoma cruzi has three distinct life cycle stages; epimastigote, trypomastigote, and amastigote. Amastigote is the replication stage in host mammalian cells, hence this stage of parasite has clinical significance in drug development research. Presence of extracellular amastigotes (EA) and their infection capability have been known for some decades. Here, we demonstrate that EA can be utilized as an axenic culture to aid in stage-specific study of T. cruzi. Amastigote-like property of axenic amastigote can be sustained in LIT medium at 37°C at least for 1 week, judging from their morphology, amastigote-specific UTR-regulated GFP expression, and stage-specific expression of selected endogenous genes. Inhibitory effect of benznidazole and nifurtimox on axenic amastigotes was comparable to that on intracellular amastigotes. Exogenous nucleic acids can be transfected into EA via conventional electroporation, and selective marker could be utilized for enrichment of transfectants. We also demonstrate that CRISPR/Cas9-mediated gene knockout can be performed in EA. Essentiality of the target gene can be evaluated by the growth capability of the knockout EA, either by continuation of axenic culturing or by host infection and following replication as intracellular amastigotes. By taking advantage of the accessibility and sturdiness of EA, we can potentially expand our experimental freedom in studying amastigote stage of T. cruzi.

Risk factors for hospitalization of patients with chikungunya virus infection at sentinel hospitals in Puerto Rico

PLoS Neglected Tropical Diseases News - 14 January 2019 - 10:00pm

by Christopher H. Hsu, Fabiola Cruz-Lopez, Danulka Vargas Torres, Janice Perez-Padilla, Olga D. Lorenzi, Aidsa Rivera, J. Erin Staples, Esteban Lugo, Jorge Munoz-Jordan, Marc Fischer, Carlos Garcia Gubern, Brenda Rivera Garcia, Luisa Alvarado, Tyler M. Sharp

Background

Hospitalization of patients during outbreaks of chikungunya virus has been reported to be uncommon (0.5–8.7%), but more frequent among infants and the elderly. CHIKV was first detected in Puerto Rico in May 2014. We enrolled patients with acute febrile illness (AFI) presenting to two hospital emergency departments in Puerto Rico and tested them for CHIKV infection to describe the frequency of detection of CHIKV-infected patients, identify risk factors for hospitalization, and describe patients with severe manifestations.

Methodology/Principal findings

Serum specimens were collected from patients with AFI and tested by rRT-PCR. During May–December 2014, a total of 3,035 patients were enrolled, and 1,469 (48.4%) had CHIKV infection. A total of 157 (10.7%) CHIKV-infected patients were hospitalized, six (0.4%) were admitted to the intensive care unit, and two died (0.1%). Common symptoms among all CHIKV-infected patients were arthralgia (82.6%), lethargy (80.6%), and myalgia (80.5%). Compared to patients aged 1–69 years (7.3%), infant (67.2%) and elderly (17.3%) patients were nine and two times more likely to be hospitalized, respectively (relative risk [RR] and 95% confidence interval [CI] = 9.16 [7.05–11.90] and 2.36 [1.54–3.62]). Multiple symptoms of AFI were associated with decreased risk of hospitalization, including arthralgia (RR = 0.31 [0.23–0.41]) and myalgia (RR = 0.29 [0.22–0.39]). Respiratory symptoms were associated with increased risk of hospitalization, including rhinorrhea (RR = 1.68 [1.24–2.27) and cough (RR = 1.77 [1.31–2.39]). Manifestations present among <5% of patients but associated with patient hospitalization included cyanosis (RR = 2.20 [1.17–4.12) and seizures (RR = 3.23 [1.80–5.81).

Discussion

Among this cohort of CHIKV-infected patients, hospitalization was uncommon, admission to the ICU was infrequent, and death was rare. Risk of hospitalization was higher in patients with symptoms of respiratory illness and other manifestations that may not have been the result of CHIKV infection.

The reemergence of human rabies and emergence of an Indian subcontinent lineage in Tibet, China

PLoS Neglected Tropical Diseases News - 14 January 2019 - 10:00pm

by Xiao-Yan Tao, Mu-Li Li, Qian Wang, Ciwang Baima, Mei Hong, Wei Li, Yong-Biao Wu, Yan-Rong Li, Yu-Min Zhao, Simon Rayner, Wu-Yang Zhu

Coordinated surveillance, vaccination and public information efforts have brought the Chinese rabies epizootic under control, but significant numbers of fatalities are still reported annually with some cases occurring in previously rabies free regions. Tibet has remained virtually rabies free for 16 years, but since 2015 one human rabies case has been reported each year. To better understand the origins of these cases, we sequenced three human samples and an additional sample isolated from a dog in 2012. Three genomes were sequenced from brain samples: human case 1 (reported in 2015), human case 3 (2017), and the 2012 dog case. For human case 2 (2016), the rabies N gene was sequenced from a limited saliva sample. Phylogenetic analysis shows that Case 1 (CXZ1501H) and the dog case (CXZ1201D) belong to China IV lineage (equivalent to Arctic-like-2 in global rabies), suggesting an association with a wildlife spillover event. However, Case 2 (CXZ1601H) is placed within the dominant lineage China I, and was most similar with recent strains from neighboring Yunnan province, indicating the current epizootic has finally reached Tibet. Most surprisingly however, was the finding that Case 3 (CXZ1704H) is distinct from other Chinese isolates. This isolate is placed in the Indian Subcontinent clade, similar to recent Nepal strains, indicating that cross-border transmission is a new source for rabies infections. Thus, the complex mixture of the rabies epizootic in Tibet represents a major new challenge for Tibet and national rabies control.

Follow-up study of high-dose praziquantel therapy for cerebral sparganosis

PLoS Neglected Tropical Diseases News - 14 January 2019 - 10:00pm

by Peng Zhang, Yang Zou, Feng-Xia Yu, Zheng Wang, Han Lv, Xue-Huan Liu, He-Yu Ding, Ting-Ting Zhang, Peng-Fei Zhao, Hong-Xia Yin, Zheng-Han Yang, Zhen-Chang Wang

Background

Cerebral sparganosis is the most serious complication of human sparganosis. Currently, there is no standard for the treatment of inoperable patients. Conventional-dose praziquantel therapy is the most reported treatment. However, the therapeutic outcomes are not very effective. High-dose praziquantel therapy is a useful therapeutic choice for many parasitic diseases that is well tolerated by patients, but it has not been sufficiently evaluated for cerebral sparganosis. This study aims to observe the prognoses following high-dose praziquantel therapy in inoperable patients and the roles of MRI and peripheral eosinophil absolute counts during follow-up.

Methodology

Baseline and follow-up epidemiological, clinical, radiological and therapeutic data related to 10 inoperable patients with cerebral sparganosis that were treated with repeated courses of high-dose praziquantel therapy, with each course consisting of 25 mg/kg thrice daily for 10 days were assessed, followed by analyses of the prognoses, MRI findings and peripheral eosinophil absolute counts.

Principal findings

Baseline clinical data: the clinical symptoms recorded included seizures, hemiparesis, headache, vomiting and altered mental status. Peripheral blood eosinophilia was found in 3 patients. The baseline radiological findings were as follows. Motile lesions were observed in 10 patients, including aggregated ring-like enhancements, tunnel signs, serpiginous and irregular enhancements. Nine of the 10 patients had varying degrees of white matter degeneration, cortical atrophy and ipsilateral ventricle dilation. The follow-up clinical data were as follows. Clinical symptom relief was found in 8 patients, symptoms were eliminated in 1 patient, and symptoms showed no change from baseline in 1 patient. Peripheral blood eosinophilia was found in 2 patients. The follow-up radiological findings were as follows. Motile lesions that were transformed into stable, chronic lesions were found in 8 patients, and motile lesions that were eliminated completely were found in 2 patients.

Conclusions

High-dose praziquantel therapy for cerebral sparganosis is effective. The radiological outcomes of motile lesions are an important indicator during the treatment process, especially during follow-ups after clinical symptoms have improved. Peripheral eosinophil absolute counts cannot be used as an effective prognostic indicator.

Metagenomic profiling of ticks: Identification of novel rickettsial genomes and detection of tick-borne canine parvovirus

PLoS Neglected Tropical Diseases News - 14 January 2019 - 10:00pm

by Anuradha Ravi, Suheir Ereqat, Amer Al-Jawabreh, Ziad Abdeen, Omar Abu Shamma, Holly Hall, Mark J. Pallen, Abedelmajeed Nasereddin

Background

Across the world, ticks act as vectors of human and animal pathogens. Ticks rely on bacterial endosymbionts, which often share close and complex evolutionary links with tick-borne pathogens. As the prevalence, diversity and virulence potential of tick-borne agents remain poorly understood, there is a pressing need for microbial surveillance of ticks as potential disease vectors.

Methodology/Principal Findings

We developed a two-stage protocol that includes 16S-amplicon screening of pooled samples of hard ticks collected from dogs, sheep and camels in Palestine, followed by shotgun metagenomics on individual ticks to detect and characterise tick-borne pathogens and endosymbionts. Two ticks isolated from sheep yielded an abundance of reads from the genus Rickettsia, which were assembled into draft genomes. One of the resulting genomes was highly similar to Rickettsia massiliae strain MTU5. Analysis of signature genes showed that the other represents the first genome sequence of the potential pathogen Candidatus Rickettsia barbariae. Ticks from a dog and a sheep yielded draft genome sequences of Coxiella strains. A sheep tick yielded sequences from the sheep pathogen Anaplasma ovis, while Hyalomma ticks from camels yielded sequences belonging to Francisella-like endosymbionts. From the metagenome of a dog tick from Jericho, we generated a genome sequence of a canine parvovirus.

Significance

Here, we have shown how a cost-effective two-stage protocol can be used to detect and characterise tick-borne pathogens and endosymbionts. In recovering genome sequences from an unexpected pathogen (canine parvovirus) and a previously unsequenced pathogen (Candidatus Rickettsia barbariae), we demonstrate the open-ended nature of metagenomics. We also provide evidence that ticks can carry canine parvovirus, raising the possibility that ticks might contribute to the spread of this troublesome virus.

Community knowledge, attitude, and perceived stigma of leprosy amongst community members living in Dhanusha and Parsa districts of Southern Central Nepal

PLoS Neglected Tropical Diseases News - 11 January 2019 - 10:00pm

by Rakesh Singh, Babita Singh, Sharika Mahato

Background

Though Nepal declared leprosy elimination in 2010, its burden is constantly rising in Terai communities for the past 2 years with 3000 new leprosy cases being diagnosed annually. Community’s perception is important for prevention and control of leprosy and enhancing quality of life of leprosy patients. Poor knowledge, unfavorable attitude and stigma create a hindrance to leprosy control. The main objective of this study was to assess the knowledge, attitude and stigma of leprosy amongst the community members living in Dhanusha and Parsa districts of Southern Central Nepal.

Methods

A total of 423 individuals were interviewed using a structured questionnaire in Dhanusha and Parsa districts. Data was analyzed using both descriptive (frequency, percentage, median) and statistical inferences (Chi-square test, Kruskal Wallis H test, Mann Whitney U test, binary logistic regression) using SPSSvs20.

Results

All respondents had heard about leprosy. Source of information on leprosy was mainly found to be health workers/hospitals (33.1%). Only 62.6% reported bacteria being its cause followed by other myths such as bad blood/curse/heredity/bad deeds (36%). Only 43.8% responded that leprosy is transmitted by prolonged close contact with leprosy patients and 25.7% reported religious rituals as the treatment. Only 42.1% had good knowledge and 40.9% had favorable attitude. Good knowledge of leprosy was highly associated with favorable attitude towards leprosy (P<0.001). The outcome variables- knowledge, attitude and EMIC score were found to have highly significant association with age, sex, ethnicity, religion, education and occupation of the respondents (P<0.001). Having knowledge on leprosy transmission was positively associated with favorable attitude towards leprosy (P<0.001).

Conclusions

Strategizing the awareness programmes according to socio-demographic characteristics for enhancing the knowledge regarding leprosy cause, symptoms, transmission, prevention and treatment, can foster the positive community attitude towards leprosy affected persons. Enhancing positive attitude towards leprosy affected persons can reduce the community stigma, thus may increase their participation in the community. Positive attitude may further increase their early health seeking behaviour including their quality of life.

DNA plasmid coding for <i>Phlebotomus sergenti</i> salivary protein PsSP9, a member of the SP15 family of proteins, protects against <i>Leishmania tropica</i>

PLoS Neglected Tropical Diseases News - 11 January 2019 - 10:00pm

by Elham Gholami, Fabiano Oliveira, Tahereh Taheri, Negar Seyed, Safoora Gharibzadeh, Nasim Gholami, Amir Mizbani, Fatemeh Zali, Sima Habibzadeh, Daniel Omid Bakhadj, Claudio Meneses, Kambiz Kamyab-Hesari, Alireza Sadeghipour, Yasaman Taslimi, Fatemeh khadir, Shaden Kamhawi, Mohammad Ali Mazlomi, Jesus G. Valenzuela, Sima Rafati

Background

The vector-borne disease leishmaniasis is transmitted to humans by infected female sand flies, which transmits Leishmania parasites together with saliva during blood feeding. In Iran, cutaneous leishmaniasis (CL) is caused by Leishmania (L.) major and L. tropica, and their main vectors are Phlebotomus (Ph.) papatasi and Ph. sergenti, respectively. Previous studies have demonstrated that mice immunized with the salivary gland homogenate (SGH) of Ph. papatasi or subjected to bites from uninfected sand flies are protected against L. major infection.

Methods and results

In this work we tested the immune response in BALB/c mice to 14 different plasmids coding for the most abundant salivary proteins of Ph. sergenti. The plasmid coding for the salivary protein PsSP9 induced a DTH response in the presence of a significant increase of IFN-γ expression in draining lymph nodes (dLN) as compared to control plasmid and no detectable PsSP9 antibody response. Animals immunized with whole Ph. sergenti SGH developed only a saliva-specific antibody response and no DTH response. Mice immunized with whole Ph. sergenti saliva and challenged intradermally with L. tropica plus Ph. sergenti SGH in their ears, exhibited no protective effect. In contrast, PsSP9-immunized mice showed protection against L. tropica infection resulting in a reduction in nodule size, disease burden and parasite burden compared to controls. Two months post infection, protection was associated with a significant increase in the ratio of IFN-γ to IL-5 expression in the dLN compared to controls.

Conclusion

This study demonstrates that while immunity to the whole Ph. sergenti saliva does not induce a protective response against cutaneous leishmaniasis in BALB/c mice, PsSP9, a member of the PpSP15 family of Ph. sergenti salivary proteins, provides protection against L. tropica infection. These results suggest that this family of proteins in Ph. sergenti, Ph. duboscqi and Ph. papatasi may have similar immunogenic and protective properties against different Leishmania species. Indeed, this anti-saliva immunity may act as an adjuvant to accelerate the cell-mediated immune response to co-administered Leishmania antigens, or even cause the activation of infected macrophages to remove parasites more efficiently. These findings highlight the idea of applying arthropod saliva components in vaccination approaches for diseases caused by vector-borne pathogens.

Improved DNA extraction technique from clot for the diagnosis of Chagas disease

PLoS Neglected Tropical Diseases News - 11 January 2019 - 10:00pm

by Holger Mayta, Yomara K. Romero, Alejandra Pando, Manuela Verastegui, Freddy Tinajeros, Ricardo Bozo, Josephine Henderson-Frost, Rony Colanzi, Jorge Flores, Richard Lerner, Caryn Bern, Robert H. Gilman, for the Chagas Working Group in Perú and Bolivia

Background

The detection of Trypanosoma cruzi genetic material in clinical samples is considered an important diagnostic tool for Chagas disease. We have previously demonstrated that PCR using clot samples yields greater sensitivity than either buffy coat or whole blood samples. However, phenol-chloroform DNA extraction from clot samples is difficult and toxic. The objective of the present study was to improve and develop a more sensitive method to recover parasite DNA from clot samples for the diagnosis of Chagas disease.

Methodology/Principal findings

A total of 265 match pair samples of whole blood–guanidine (GEB) and clot samples were analyzed; 150 were from Chagas seropositive subjects. DNA was extracted from both whole blood-guanidine samples, using a previously standardized methodology, and from clot samples, using a newly developed methodology based on a combination of the FastPrep technique and the standard method for GEB extraction. A qPCR targeting the nuclear satellite sequences was used to compare the sample source and the extraction method. Of the 150 samples from Chagas positive individuals by serology, 47 samples tested positive by qPCR with DNA extracted by both GEB and clot, but an additional 13 samples tested positive only in DNA extracted from clot. No serology-negative samples resulted positive when tested by qPCR.

Conclusions

The new methodology for DNA extraction from clot samples improves the molecular diagnosis of Chagas disease.

Antagonistic effects of <i>Plasmodium</i>-helminth co-infections on malaria pathology in different population groups in Côte d’Ivoire

PLoS Neglected Tropical Diseases News - 10 January 2019 - 10:00pm

by Eveline Hürlimann, Clarisse A. Houngbedji, Richard B. Yapi, Prisca B. N’Dri, Kigbafori D. Silué, Mamadou Ouattara, Jürg Utzinger, Eliézer K. N’Goran, Giovanna Raso

Introduction

Plasmodium spp. and helminths are co-endemic in many parts of the tropics; hence, co-infection is a common phenomenon. Interactions between Plasmodium and helminth infections may alter the host’s immune response and susceptibility and thus impact on morbidity. There is little information on the direction and magnitude of such interactions and results are conflicting. This study aimed at shedding new light on the potential interactions of Plasmodium and helminth co-infections on anemia and splenomegaly in different population groups in Côte d’Ivoire.

Methodology

Parasitologic and clinical data were obtained from four cross-sectional community-based studies and a national school-based survey conducted between 2011 and 2013 in Côte d’Ivoire. Six scenarios of co-infection pairs defined as Plasmodium infection or high parasitemia, combined with one of three common helminth infections (i.e., Schistosoma mansoni, S. haematobium, and hookworm) served for analysis. Adjusted logistic regression models were built for each scenario and interaction measures on additive scale calculated according to Rothman, while an interaction term in the model served as multiplicative scale measure.

Principal findings

All identified significant interactions were of antagonistic nature but varied in magnitude and species combination. In study participants aged 5–18 years from community-based studies, Plasmodium-hookworm co-infection showed an antagonistic interaction on additive scale on splenomegaly, while Plasmodium-Schistosoma co-infection scenarios showed protective effects on multiplicative scale for anemia and splenomegaly in participants aged 5–16 years from a school-based study.

Conclusions/Significance

No exacerbation from co-infection with Plasmodium and helminths was observed, neither in participants aged 5–18 years nor in adults from the community-based studies. Future studies should unravel underlying mechanisms of the observed interactions, as this knowledge might help shaping control efforts against these diseases of poverty.

Economic burden of dengue in Indonesia

PLoS Neglected Tropical Diseases News - 10 January 2019 - 10:00pm

by Mardiati Nadjib, Ery Setiawan, Septiara Putri, Joshua Nealon, Sophie Beucher, Sri Rezeki Hadinegoro, Vetty Yulianty Permanasari, Kurnia Sari, Tri Yunis Miko Wahyono, Erna Kristin, Dewa Nyoman Wirawan, Hasbullah Thabrany

Background

Dengue is associated with significant economic expenditure and it is estimated that the Asia Pacific region accounts for >50% of the global cost. Indonesia has one of the world’s highest dengue burdens; Aedes aegypti and Aedes albopictus are the primary and secondary vectors. In the absence of local data on disease cost, this study estimated the annual economic burden during 2015 of both hospitalized and ambulatory dengue cases in Indonesia.

Methods

Total 2015 dengue costs were calculated using both prospective and retrospective methods using data from public and private hospitals and health centres in three provinces: Yogyakarta, Bali and Jakarta. Direct costs were extracted from billing systems and claims; a patient survey captured indirect and out-of-pocket costs at discharge and 2 weeks later. Adjustments across sites based on similar clinical practices and healthcare landscapes were performed to fill gaps in cost estimates. The national burden of dengue was extrapolated from provincial data using data from the three sites and applying an empirically-derived epidemiological expansion factor.

Results

Total direct and indirect costs per dengue case assessed at Yogyakarta, Bali and Jakarta were US$791, US$1,241 and US$1,250, respectively. Total 2015 economic burden of dengue in Indonesia was estimated at US$381.15 million which comprised US$355.2 million for hospitalized and US$26.2 million for ambulatory care cases.

Conclusion

Dengue imposes a substantial economic burden for Indonesian public payers and society. Complemented with an appropriate weighting method and by accounting for local specificities and practices, these data may support national level public health decision making for prevention/control of dengue in public health priority lists.

Emergence of <i>Madariaga virus</i> as a cause of acute febrile illness in children, Haiti, 2015-2016

PLoS Neglected Tropical Diseases News - 10 January 2019 - 10:00pm

by John A. Lednicky, Sarah K. White, Carla N. Mavian, Maha A. El Badry, Taina Telisma, Marco Salemi, Bernard A. OKech, V. Madsen Beau De Rochars, J. Glenn Morris Jr.

Madariaga virus (MADV), also known as South American eastern equine encephalitis virus, has been identified in animals and humans in South and Central America, but not previously in Hispaniola or the northern Caribbean. MADV was isolated from virus cultures of plasma from an 8-year-old child in a school cohort in the Gressier/Leogane region of Haiti, who was seen in April, 2015, with acute febrile illness (AFI). The virus was subsequently cultured from an additional seven AFI case patients from this same cohort in February, April, and May 2016. Symptoms most closely resembled those seen with confirmed dengue virus infection. Sequence data were available for four isolates: all were within the same clade, with phylogenetic and molecular clock data suggesting recent introduction of the virus into Haiti from Panama sometime in the period from October 2012-January 2015. Our data document the movement of MADV into Haiti, and raise questions about the potential for further spread in the Caribbean or North America.

Assessing the risk of autochthonous yellow fever transmission in Lazio, central Italy

PLoS Neglected Tropical Diseases News - 10 January 2019 - 10:00pm

by Mattia Manica, Giorgio Guzzetta, Federico Filipponi, Angelo Solimini, Beniamino Caputo, Alessandra della Torre, Roberto Rosà, Stefano Merler

Differential replication efficiencies between Japanese encephalitis virus genotype I and III in avian cultured cells and young domestic ducklings

PLoS Neglected Tropical Diseases News - 18 December 2018 - 10:00pm

by Changguang Xiao, Chenxi Li, Di Di, Julien Cappelle, Lihong Liu, Xin Wang, Linlin Pang, Jinpeng Xu, Ke Liu, Beibei Li, Donghua Shao, Yafeng Qiu, Weijie Ren, Frederik Widén, Véronique Chevalier, Jianchao Wei, Xiaodong Wu, Zhiyong Ma

Japanese encephalitis virus (JEV) genotype dominance has shifted to genotype I (GI) from genotype III (GIII) in China as demonstrated by molecular epidemiological surveillance. In this study, we performed a serological survey in JEV-non-vaccinated pigs to confirm JEV genotype shift at the sero-epidemiological level. The average ratio of GI/GIII infection was 1.87, suggesting co-circulation of GI and GIII infections with GI infection being more prevalent in pigs in China. To gain an insight into the reasons for this JEV genotype shift, the replication kinetics of seven recently-isolated JEV isolates including three GI strains and four GIII strains were compared in mosquito C6/36 cells, chicken fibroblast cells (DF-1) and porcine iliac artery endothelial cells (PIEC). We observed that GI strains replicated more efficiently than GIII strains in DF-1 and PIEC cells, particularly in DF-1 cells with titers reaching 22.9–225.3 fold higher than GIII strains. This shows an enhanced replication efficiency of GI viruses in avian cells. To examine this enhanced replication efficiency in vivo, young domestic ducklings were used as the animal model and inoculated with GI and GIII strains at day 2 post-hatching. We observed that GI-inoculated ducklings developed higher viremia titers and displayed a comparatively longer viremic duration than GIII-inoculated ducklings. These results conform to the hypothesis of an enhanced replication efficiency for GI viruses in birds. There are 36 amino acid differences between GI and GIII viruses, some of which may be responsible for the enhanced replication efficiency of GI viruses in birds. Based on these findings, we speculated that the enhanced replication of GI viruses in birds would have resulted in higher exposure and therefore infection in mosquitoes, which could result in an increased transmission efficiency of GI viruses in the birds-mosquitoes-birds enzootic transmission cycle, thereby contributing to JEV genotype shift.

NMR metabolomics of cerebrospinal fluid differentiates inflammatory diseases of the central nervous system

PLoS Neglected Tropical Diseases News - 17 December 2018 - 10:00pm

by Caitlin D. French, Rodney E. Willoughby, Amy Pan, Susan J. Wong, John F. Foley, L. Joseph Wheat, Josefina Fernandez, Rafael Encarnacion, Joanne M. Ondrush, Naaz Fatteh, Andres Paez, Dan David, Waleed Javaid, Ioana G. Amzuta, Anne M. Neilan, Gregory K. Robbins, Andrew M. Brunner, William T. Hu, Darya O. Mishchuk, Carolyn M. Slupsky

Background

Myriad infectious and noninfectious causes of encephalomyelitis (EM) have similar clinical manifestations, presenting serious challenges to diagnosis and treatment. Metabolomics of cerebrospinal fluid (CSF) was explored as a method of differentiating among neurological diseases causing EM using a single CSF sample.

Methodology/Principal findings

1H NMR metabolomics was applied to CSF samples from 27 patients with a laboratory-confirmed disease, including Lyme disease or West Nile Virus meningoencephalitis, multiple sclerosis, rabies, or Histoplasma meningitis, and 25 controls. Cluster analyses distinguished samples by infection status and moderately by pathogen, with shared and differentiating metabolite patterns observed among diseases. CART analysis predicted infection status with 100% sensitivity and 93% specificity.

Conclusions/Significance

These preliminary results suggest the potential utility of CSF metabolomics as a rapid screening test to enhance diagnostic accuracies and improve patient outcomes.

Widespread circulation of West Nile virus, but not Zika virus in southern Iran

PLoS Neglected Tropical Diseases News - 17 December 2018 - 10:00pm

by Mazyar Ziyaeyan, Mohammad Amin Behzadi, Victor Hugo Leyva-Grado, Kourosh Azizi, Gholamreza Pouladfar, Hedayat Dorzaban, Atoosa Ziyaeyan, Sanaz Salek, Aghyl Jaber Hashemi, Marzieh Jamalidoust

West Nile virus (WNV) and Zika virus (ZIKV) are mosquito-borne viral infections. Over the past few decades, WNV has been associated with several outbreaks involving high numbers of neuroinvasive diseases among humans. The recent re-emergence of ZIKV has been associated with congenital malformation and also with Guillain–Barre syndrome in adults. The geographic range of arthropod-borne viruses has been rapidly increasing in recent years. The objectives of this study were to determine the presence of IgG specific antibodies and the genome of WNV and ZIKV in human samples, as well as WNV and ZIKV genomes in wild-caught mosquitoes in urban and rural areas of the Hormozgan province, in southern Iran. A total of 494 serum samples were tested for the presence of WNV and ZIKV IgG antibodies using ELISA assays. One hundred and two (20.6%) samples were reactive for WNV IgG antibodies. All serum samples were negative for ZIKV IgG antibodies. Using the multivariable logistic analysis, age (45+ vs. 1–25; OR = 3.4, 95% C.I.: 1.8–6.3), occupation (mostly outdoor vs. mostly indoor; OR = 2.4, 95% C.I.: 1.1–5.2), and skin type(type I/II vs. type III/IV and type V/VI; OR = 4.3, 95% C.I.: 1.7–10.8 and OR = 2.7, 95% C.I.: 1.3–5.5 respectively, skin types based on Fitzpatrick scale) showed significant association with WNV seroreactivity. We collected 2,015 mosquitoes in 136 pools belonging to 5 genera and 14 species. Three pools of Culex pipiens complex were positive for WNV RNA using real-time reverse transcription polymerase chain reaction (rtRT-PCR). ZIKV RNA was not detected in any of the pools. All WNV ELISA reactive serum samples were negative for WNV RNA. In conclusion, we provided evidence of the establishment of WNV in southern Iran and no proof of ZIKV in serum samples or in mosquito vectors. The establishment of an organized arbovirus surveillance system and active case finding strategies seems to be necessary.

Diisopropylphenyl-imidazole (DII): A new compound that exerts anthelmintic activity through novel molecular mechanisms

PLoS Neglected Tropical Diseases News - 17 December 2018 - 10:00pm

by María Gabriela Blanco, María Soledad Vela Gurovic, Gustavo Fabián Silbestri, Andrés Garelli, Sebastián Giunti, Diego Rayes, María José De Rosa

Nematode parasites cause substantial morbidity to billions of people and considerable losses in livestock and food crops. The repertoire of effective anthelmintic compounds for treating these parasitoses is very limited, as drug development has been delayed for decades. Moreover, resistance has become a global concern in livestock parasites and is an emerging issue for human helminthiasis. Therefore, anthelmintics with novel mechanisms of action are urgently needed. Taking advantage of Caenorhabditis elegans as an established model system, we here screened the nematicidal potential of novel imidazolium and imidazole derivatives. One of these derivatives, diisopropylphenyl-imidazole (DII), is lethal to C. elegans at both mature and immature stages. This lethal effect appears to be specific because DII concentrations which prove to be toxic to C. elegans do not induce significant lethality on bacteria, Drosophila melanogaster, and HEK-293 cells. Our analysis of DII action on C. elegans mutant strains determined that, in the adult stage, null mutants of unc-29 are resistant to the drug. Muscle expression of this gene completely restores DII sensitivity. UNC-29 has been largely reported as an essential constituent of the levamisole-sensitive muscle nicotinic receptor (L-AChR). Nevertheless, null mutants in unc-63 and lev-8 (essential and non-essential subunits of L-AChRs, respectively) are as sensitive to DII as the wild-type strain. Therefore, our results suggest that DII effects on adult nematodes rely on a previously unidentified UNC-29-containing muscle AChR, different from the classical L-AChR. Interestingly, DII targets appear to be different between larvae and adults, as unc-29 null mutant larvae are sensitive to the drug. The existence of more than one target could delay resistance development. Its lethality on C. elegans, its harmlessness in non-nematode species and its novel and dual mechanism of action make DII a promising candidate compound for anthelmintic therapy.

Robustness of the reproductive number estimates in vector-borne disease systems

PLoS Neglected Tropical Diseases News - 17 December 2018 - 10:00pm

by Warren Tennant, Mario Recker

Background

The required efforts, feasibility and predicted success of an intervention strategy against an infectious disease are partially determined by its basic reproduction number, R0. In its simplest form R0 can be understood as the product of the infectious period, the number of infectious contacts and the per-contact transmission probability, which in the case of vector-transmitted diseases necessarily extend to the vector stages. As vectors do not usually recover from infection, they remain infectious for life, which places high significance on the vector’s life expectancy. Current methods for estimating the R0 for a vector-borne disease are mostly derived from compartmental modelling frameworks assuming constant vector mortality rates. We hypothesised that some of the assumptions underlying these models can lead to unrealistic high vector life expectancies with important repercussions for R0 estimates.

Methodology and principal findings

Here we used a stochastic, individual-based model which allowed us to directly measure the number of secondary infections arising from one index case under different assumptions about vector mortality. Our results confirm that formulas based on age-independent mortality rates can overestimate R0 by nearly 100% compared to our own estimate derived from first principles. We further provide a correction factor that can be used with a standard R0 formula and adjusts for the discrepancies due to erroneous vector age distributions.

Conclusion

Vector mortality rates play a crucial role for the success and general epidemiology of vector-transmitted diseases. Many modelling efforts intrinsically assume these to be age-independent, which, as clearly demonstrated here, can lead to severe over-estimation of the disease’s reproduction number. Our results thus re-emphasise the importance of obtaining field-relevant and species-dependent vector mortality rates, which in turn would facilitate more realistic intervention impact predictions.

Pages