Recent updates on onchocerciasis: diagnosis and treatment

Onchocercoma of the scalp: A case report

Onchocerciasis or river blindness is a parasitic disease caused by Onchocerca volvulus transmitted to humans by the byte of a black fly of the species Simulium. This pathology, which is a part of the Neglected tropical Disease (NTDs), has been resurgent for some years in certain regions of Burkina Faso. We report a case of onchocercoma with the aim of describing the anatomopathological aspects of this pathology. These were two (02) biopsy fragments from a scalp nodule in an 8-year-old boy, received in the pathology laboratory for examination. In this case study, we recall that onchocerciasis is manifested mainly by skin lesions, subcutaneous nodules and ocular lesions. Histologically, the skin lesions present as a dermatitis with adult worms in the superficial dermis within a predominantly eosinophilic inflammatory infiltrate. Nodules or onchocercomas, usually subcutaneous, consist of fibrous, inflammatory tissue with a predominance of eosinophils and adult worms including females containing microfilariae. Ocular lesions begin with punctate keratitis with a snowflake image. Sclerosis with opacification of the cornea progressively sets in, causing blindness.

Concordance between Ov16 Rapid Diagnostic Test(RDT) and Ov16 Enzyme-Linked Immunosorbent Assay (ELISA) for the Diagnosis of Onchocerciasis in Areas of Contrasting Endemicity in Cameroon

The diagnosis of onchocerciasis in endemic areas has been demanding given the need to replace the invasive skin snip method with a more sensitive and specific rapid point-of-contact tool. Filarial antigen detection tests are better alternative methods in diagnosing Onchocercal infections, as they detect infections and could be used to monitor transmission in endemic areas following mass drug administration. With the shift in paradigme from control to elimination, a rapid point- of-contact tool is required to support elimination programs. This was a cross-sectional, community-based study conducted in 50 villages selected from six health districts using a systematic sampling technique. Individuals ≥17 years who had lived in the community for a duration of 5 years and above provided blood specimens for IgG4 antibodies testing against O. volvulus antigens. Data were analyzed using SPSS v.20 and expectation maximization to classify optical densities for positive and negative samples from ELISA results. The kappa statistics was used to measure the level of agreement between the two tests. In a total of 5001 participants which were recruited for the study, 4416 (88.3 %) participant samples passed the plate quality control criteria and were considered for the test comparison analysis. Out of the 4416 participants, 292 (6.6 %) tested positive with Ov16 RDT and 310 (7.0 %) with Ov16 ELISA. All those who tested positive with the rapid test agreed positive with ELISA. The overall percentage agreement was 99.2 %, the Kappa score of 0.936. The results obtained indicate an excellent agreement between ELISA and RDT as measured by kappa (0.936) which was statistically significant (P<0.001). Our experience with the Ov16 ELISA biplex rapid test was favorable. However, the Ov16 RDT test may be more appropriate to use in remote areas for the point diagnosis of onchocerciasis in view towards achieving elimination in Africa.

Evaluating the impact of alternative intervention strategies in accelerating onchocerciasis elimination in an area of persistent transmission in the West Region of Cameroon

BACKGROUND

Alternative strategies are recommended to accelerate onchocerciasis elimination in problematic areas including areas where annual ivermectin (IVM) distributions are unable to interrupt transmission. The aim of this study was to accelerate progress towards elimination in the Massangam health district, West Region of Cameroon where impact evaluations demonstrated ongoing transmission of onchocerciasis infection and high microfilaria (mf) prevalence despite more than 20 years of annual IVM distribution.

METHODOLOGY/PRINCIPAL FINDINGS

Parasitological, entomological, and breeding site surveys were conducted in 2015 delineating a focus of high transmission and identified three communities with high mf prevalence. Individuals in these communities were screened for mf yearly for a period of two years and those positive treated each year with doxycycline 100mg daily for five weeks. In addition, surrounding communities were given biannual IVM. Temephos-based applications were performed once a week for 10 consecutive weeks on Simulium damnosum s.l. breeding sites. Parasitological and entomological assessments were conducted after two years of implementation and findings compared with 2015 baseline. Alternative strategies accelerated progress towards elimination through a significant mf reduction (χ2: 40.1; p<0.001) from 35.7% (95%CI: 29.0-42.8) to 12.3% (95%CI, 9.0-16.4). Reductions were furthermore recorded over a longer period, with a reduction of prevalence of 29.0% under AIS in 2017-2019 compared to 14.6% with IVM in 2011-2015; and by 23.2% following the two years of alternative strategies compared to 20.3% reduction over 15 years of treatment with IVM (1996-2011). Entomological assessment demonstrates that transmission is still ongoing despite the reduction in mf which is expected in an environment with complex breeding sites and open transmission zones, i.e., where migration of flies or humans to and from neighbouring areas is common.

CONCLUSION/SIGNIFICANCE

This study provides evidence that alternative strategies are feasible and effective and should be considered in areas where transmission is sustained throughout long term uninterrupted MDA with IVM. However, there is need to consider wider transmission zones, and further explore optimal timing of larviciding with treatment to impact transmission.

High Prevalence of Glaucoma among Patients in an Onchocerciasis Endemic Area (Mahenge, Tanzania)

Onchocerciasis is known to cause skin lesions and blindness, but there is also epidemiological evidence that onchocerciasis is associated with epilepsy, including nodding syndrome. We carried out ocular exams in persons with epilepsy in Mahenge, an onchocerciasis endemic area with a high prevalence of epilepsy in Tanzania. We recruited 278 consecutive persons with epilepsy attending the epilepsy clinic at Mahenge hospital and satellite clinics in rural villages. They underwent a general physical and a detailed ocular examination and were tested for onchocerciasis Ov16 IgG4 antibodies. Glaucoma was defined by a raised intraocular pressure above 21 mmHg with evidence of typical glaucomatous disc changes in one or both eyes. Among the 278 participants, median age 27 (IQR 21–38) years, 55.4% were female; 151/210 (71.9%) (95% CI: 65.3–77.9) were Ov16 positive. The most frequent ophthalmic lesions were glaucoma (33.1%), vitreous opacities (6.5%) and cataracts (2.9%). In multivariate analysis, glaucoma (adjusted IRR = 1.46; 95% CI: 1.24–1.70) and age (adjusted IRR = 1.01; 95% CI: 1.01–1.02) were significantly associated with onchocerciasis. In conclusion, a high prevalence of glaucoma was observed among Ov16 positive persons with epilepsy. Persons with epilepsy with O. volvulus infection should undergo screening for glaucoma to prevent one of the causes of preventable blindness.

P2R Inhibitors Prevent Antibody-Mediated Complement Activation in an Animal Model of Neuromyelitis Optica : P2R Inhibitors Prevent Autoantibody Injury

Purinergic 2 receptors (P2Rs) contribute to disease-related immune cell signaling and are upregulated in various pathological settings, including neuroinflammation. P2R inhibitors have been used to treat inflammatory diseases and can protect against complement-mediated cell injury. However, the mechanisms behind these anti-inflammatory properties of P2R inhibitors are not well understood, and their potential in CNS autoimmunity is underexplored. Here, we tested the effects of P2R inhibitors on glial toxicity in a mouse model of neuromyelitis optica spectrum disorder (NMOSD). NMOSD is a destructive CNS autoimmune disorder, in which autoantibodies against astrocytic surface antigen Aquaporin 4 (AQP4) mediate complement-dependent loss of astrocytes. Using two-photon microscopy in vivo, we found that various classes of P2R inhibitors prevented AQP4-IgG/complement-dependent astrocyte death. In vitro, these drugs inhibited the binding of AQP4-IgG or MOG-IgG to their antigen in a dose-dependent manner. Size-exclusion chromatography and circular dichroism spectroscopy revealed a partial unfolding of antibodies in the presence of various P2R inhibitors, suggesting a shared interference with IgG antibodies leading to their conformational change. Our study demonstrates that P2R inhibitors can disrupt complement activation by direct interaction with IgG. This mechanism is likely to influence the role of P2R inhibitors in autoimmune disease models and their therapeutic impact in human disease.

Relationship between skin snip and Ov16 ELISA: Two diagnostic tools for onchocerciasis in a focus in Cameroon after two decades of ivermectin-based preventive chemotherapy

Background

Onchocerciasis elimination currently relies on repeated ivermectin-based preventive chemotherapy. Current World Health Organization’s guidelines strongly recommend, though with low evidence of certainty, the use of Ov16 serology testing in children younger than 10 years old to assess whether mass drugs administration can be safely stopped. Therefore, more evidences are needed to support the use of this marker as sero-evaluation tool. This study aimed at determining the relationship between microfilaridermia and anti-Ov16 IgG4, and their variation according to age, gender and ivermectin intake history.

Methodology

A cross-sectional survey was conducted in an area where ivermectin-based MDA has been implemented since more than 20 years. A questionnaire was used to record ivermectin intake history for the last 5 years. All volunteers aged ≥2 years were tested for microfilaridermia. IgG4 antibodies against Ov16 antigen were determined using the Standard Diagnostic Ov16 IgG4 ELISA kits and the recombinant anti-Ov16 AbD19432 antibodies. Prevalences, microfilaridermia counts and IgG4 concentrations were compared with regards to age, gender and history of ivermectin intake.

Principal findings

The prevalence of skin microfilariae was 23.4% (95% CI: 23.4–30.8), whereas Ov16 seroprevalence was 53.2% (95% CI: 47.9–58.4). A moderate positive percentage agreement (50.4%) and a high negative percentage agreement (69.2%) was found between skin snip and Ov16 serology in the whole population, while in children aged <10 years, the agreements were higher (positive percentage agreement: 62.6%; negative percentage agreement: 83.5%). In addition, no associations were found between ivermectin intake, Mf counts and estimated IgG4 concentration of participants. Anti-Ov16 IgG4 were higher in individuals harboring microfilariae than their negative counterparts (p<0.0001), though a negative correlation was found between skin microfilarial counts and anti-Ov16 IgG4 levels (r = -0.2400; p = 0.03). No variation in microfilarial counts according to age and gender was observed. Though positively correlated with age (r = 0.4020; p<0.0001), IgG4 was significantly different between the different age classes (p<0.0001).

Conclusion/Significance

Our results revealed moderate positive and negative agreements between parasitological and immunological parameters of onchocerciasis infection after several rounds MDA. Anti-Ov16 IgG4 levels increased with age but decreased with microfilarial counts, suggesting a variation of anti-Ov16 IgG4 as a result of constant exposure and accumulation of infection. This brings evidence sustaining the use of Ov16 serology in children as evaluation tool. However, additional investigations are needed to further reshape the appropriate age range among children aged <10 years old.

The elimination of onchocerciasis places high demands on monitoring and evaluation. The current WHO’s guidelines recommend the use of serological test (ELISA) to determine the presence of IgG4 antibodies to the O. volvulus specific antigen Ov16 among children aged <10 years old, thought with low evidence of certainty. In this paper, we explored the relationship between anti-Ov16 IgG4 antibodies and microfilaridermia counts, and assessed their variation according to age, gender and history of ivermectin intake. Our findings revealed no variation of Mf count and IgG4 with ivermectin intake. However, we observed that anti-Ov16 IgG4 decrease with microfilaridermia counts, but an increasing trend was observed with age. This brings evidence sustaining the use of Ov16 serology testing as exposition marker in children younger than 10 years. However, children age 2 to 4 years seem to have a very low anti-Ov16 IgG4 concentration, this finding should be considered when defining the age class for seroprevalence evaluation.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.

Current and future strategies against cutaneous parasites

Cutaneous parasites are identified by their specific cutaneous symptoms which are elicited based on the parasite's interactions with the host. Standard anti-parasitic treatments primarily focus on the use of specific drugs to disrupt the regular function of the target parasite. In cases where secondary infections are induced by the parasite itself, antibiotics may also be used in tandem with the primary treatment to deal with the infection. Whilst drug-based treatments are highly effective, the development of resistance by bacteria and parasites, is increasingly prevalent in the modern day, thus requiring the development of non-drug based anti-parasitic strategies. Cutaneous parasites vary significantly in terms of the non-systemic methods that are required to deal with them. The main factors that need to be considered are the specifically elicited cutaneous symptoms and the relative cutaneous depth in which the parasites typically reside in. Due to the various differences in their migratory nature, certain cutaneous strategies are only viable for specific parasites, which then leads to the idea of developing an all-encompassing anti-parasitic strategy that works specifically against cutaneous parasites. The main benefit of this would be the overall time saved in regards to the period that is needed for accurate diagnosis of parasite, coupled with the prescription and application of the appropriate treatment based on the diagnosis. This review will assess the currently identified cutaneous parasites, detailing their life cycles which will allow for the identification of certain areas that could be exploited for the facilitation of cutaneous anti-parasitic treatment.

Bacteriome Diversity of Blackflies' Gut and Association with Onchocerca volvulus, the Causative Agent of Onchocerciasis in Mbam Valley (Center Region, Cameroon)

Vector control using larvicides is the main alternative strategy to address limits of preventive chemotherapy using ivermectin for the control of onchocerciasis. However, it remains substantially limited by implementation difficulties, ecological concerns and the resistance of vector populations. Therefore, efficient and environmentally safe alternative control strategies are still needed. This study explores the composition of the blackfly bacteriome and its variability in the presence of Onchocerca volvulus infection, in order to determine their potential as a novel vector control-based approach to fight onchocerciasis. An entomological survey of a collection of samples was performed in the Bafia health district, a historical endemic focus for onchocerciasis in Cameroon. A total of 1270 blackflies were dissected and the infection rate was 10.1%, indicative of ongoing transmission of onchocerciasis in the surveyed communities. Sequencing process of blackflies’ gut DNA for bacteria screening revealed 14 phyla and 123 genera, highlighting the diversity of gut blackflies bacterial communities. Eight bacteria formed the core of blackfly bacteriome and Wolbachia was the predominant genus with 73.4% of relative abundance of blackflies’ gut bacterial communities. Acidomonas and Roseanomas genera were significantly abundant among infected blackflies (p = 0.01), whereas other genera such as Brevibacterium and Fructobacillus were associated with the absence of infection (p = 0.0009). Differences in gut bacterial distribution of blackflies according to their infection status by the parasite suggest a causal relationship between the bacteriome composition and the onset of blackflies’ infection by O. volvulus or vice versa. Blackfly native bacteria are then potentially involved in infection by O. volvulus, either by facilitating or preventing the parasite infestation of the vector. These bacteria represent an interesting potential as a biological tool/target for a novel approach of vector control to fight onchocerciasis.

An annotated checklist of the eukaryotic parasites of humans, exclusive of fungi and algae

The classification of "parasites" in the medical field is a challenging notion, a group which historically has included all eukaryotes exclusive of fungi that invade and derive resources from the human host. Since antiquity, humans have been identifying and documenting parasitic infections, and this collective catalog of parasitic agents has expanded considerably with technology. As our understanding of species boundaries and the use of molecular tools has evolved, so has our concept of the taxonomy of human parasites. Consequently, new species have been recognized while others have been relegated to synonyms. On the other hand, the decline of expertise in classical parasitology and limited curricula have led to a loss of awareness of many rarely encountered species. Here, we provide a comprehensive checklist of all reported eukaryotic organisms (excluding fungi and allied taxa) parasitizing humans resulting in 274 genus-group taxa and 848 species-group taxa. For each species, or genus where indicated, a concise summary of geographic distribution, natural hosts, route of transmission and site within human host, and vectored pathogens are presented. Ubiquitous, human-adapted species as well as very rare, incidental zoonotic organisms are discussed in this annotated checklist. We also provide a list of 79 excluded genera and species that have been previously reported as human parasites but are not believed to be true human parasites or represent misidentifications or taxonomic changes.

Morgellons Disease: The Spread of a Mass Psychogenic Illness via the Internet and Its Implications in Hand Surgery

Somatic manifestations of mental illness sometimes occur in patients presenting to hand specialists. These conversion disorders can also occur in groups, a phenomenon known as "mass psychogenic illness." The increasing penetrance of the Internet and social media in modern society has greatly facilitated the interaction of patients with others with similar disorders. One example relevant to hand surgery is "Morgellons disease," a disorder popularized in 2002 and characterized by a firm belief in foreign material extruding from the skin, leading to nonhealing, self-inflicted ulcerations and excoriations. A series of 4 patients collected through an informal survey of hand surgeons regarding experience with Morgellons disease is reviewed and discussed. All patients in the series presented with a chief complaint of foreign material extruding from the hand. In 1 case, the complaint was made by a young patient's mother. In none of the patients were foreign bodies identified, although 2 patients demonstrated significant ulcerations and scars from self-excoriation. Three patients had a somatic condition affecting the hand or upper extremity, 1 directly related to self-excoriation and 2 unrelated. Treatments, workups, and ultimate outcomes varied among patients. Patients presenting with Morgellons disease often undergo multiple unnecessary tests and are at risk of inappropriate procedures. It is therefore important that providers have a compassionate understanding of the involved psychology. Herein, we offer an approach to the recognition of and treatment strategies for these patients.

Human filariasis in travelers and migrants: a retrospective 25-year analysis at the Institute of Tropical Medicine, Antwerp, Belgium

BACKGROUND

Information on human filariasis in international travelers is scarce. We describe the epidemiology, clinical presentation and outcome of these infections in a reference travel clinic over the past decades.

METHODS

We reviewed all cases of filariasis diagnosed at the Institute of Tropical Medicine, Antwerp, Belgium, from 1994 to 2018. Diagnosis was obtained by either parasitological methods (confirmed) or strict clinical case definitions (probable). We assessed the characteristics of cases at diagnosis and response to therapy within three to 12 months.

RESULTS

A total of 320 patients (median age: 41 years; 71% males) were diagnosed with 327 filarial infections (Wuchereria bancrofti = 6; Onchocerca volvulus = 33, Loa loa = 150, Mansonella perstans = 130; unspecified species = 8). Diagnosis was confirmed in 213/320 (67%) patients. European long-term travelers accounted for 166 patients (52%) and visitors/migrants from tropical countries for another 110 (34%). Central Africa was the likely region of acquisition for 294 (92%) patients. The number of filariasis cases decreased from 21.5/year in average in the nineties to 6.3/year in the last decade, when loiasis became predominant. Cases reported symptoms in > 80% of all filarial infections but mansonellosis (45/123 single infections; 37%). Lymphatic filariasis and onchocerciasis cases responded well to conventional therapy. However, 30% of patients with loiasis and mansonellosis experienced treatment failure (with diethylcarbamazine and levamisole-mebendazole, respectively).

CONCLUSIONS

The burden and species distribution of filariasis in travelers evolved in the past decades. Most presentations were symptomatic. Case management would benefit from more effective therapies for loiasis and mansonellosis.

Epilepsy in Onchocerca volvulus Sero-Positive Patients From Northern Uganda-Clinical, EEG and Brain Imaging Features

Globally, epilepsy is the most common chronic neurological disorder. The incidence in sub-Saharan Africa is 2-3 times higher than that in high income countries. Infection by Onchocerca volvulus may be an underlying risk factor for the high burden and based upon epidemiological associations, has been proposed to cause a group of disorders—Onchocerca associated epilepsies (OAE) like nodding syndrome (NS). To improve our understanding of the disease spectrum, we described the clinical, electroencephalographic (EEG) and magnetic resonance imaging (MRI) features of children with epilepsy and sero-positive for Onchocerca volvulus (possible OAEs other than nodding syndrome). Twenty-nine children and adolescents with non-nodding syndrome OAE in northern Uganda were enrolled. A diagnosis of OAE was made in patients with epilepsy and seizure onset after age 3 years, no reported exposure to perinatal severe febrile illness or traumatic brain injury, no syndromic epilepsy diagnosis and a positive Ov-16 ELISA test. Detailed clinical evaluation including psychiatric, diagnostic EEG, a diagnostic brain MRI (in 10 patients) and laboratory testing were performed. Twenty participants (69%) were male. The mean age was 15.9 (standard deviation [SD] 1.9) years while the mean age at seizure onset was 9.8 (SD 2.9) years. All reported normal early childhood development. The most common clinical presentation was a tonic-clonic seizure. The median number of seizures was 2 (IQR 1–4) in the previous month. No specific musculoskeletal changes, or cranial nerve palsies were reported, neither were any vision, hearing and speech difficulties observed. The interictal EEG was abnormal in the majority with slow wave background activity in 52% (15/29) while 41% (12/29) had focal epileptiform activity. The brain MRI showed mild to moderate cerebellar atrophy and varying degrees of atrophy of the frontal, parietal and occipital lobes. The clinical spectrum of epilepsies associated with Onchocerca may be broader than previously described. In addition, focal onset tonic-clonic seizures, cortical and cerebellar atrophy may be important brain imaging and clinical features.

Filariasis and transfusion-associated risk: a literature review

BACKGROUND AND OBJECTIVES

Filariae are parasitic worms that include the pathogens Loa loa, Onchocerca volvulus, Wuchereria bancrofti, Brugia spp. and Mansonella spp. which are endemic in parts of Africa, Asia, Asia-Pacific, South and Central America. Filariae have a wide clinical spectrum spanning asymptomatic infection to chronic debilitating disease including blindness and lymphedema. Despite successful eradication programmes, filarial infections remain an important -albeit neglected - source of morbidity. We sought to characterize the risk of transfusion transmission of microfilaria with a view to guide mitigation practices in both endemic and non-endemic countries.

MATERIALS AND METHODS

A scoping review of scientific publications as well as grey literature was carried out by a group of domain experts in microbiology, transfusion medicine and infectious diseases, representing the parasite subgroup of the International Society of Blood Transfusion.

RESULTS

Cases of transfusion-transmitted filariasis are rare and confined to case reports of variable quality. Transfusion-associated adverse events related to microfilariae are confined to isolated reports of transfusion reactions. Serious outcomes have not been reported. No known strategies have been implemented, specifically, to mitigate transfusion-transmitted filariasis yet routine blood donor screening for other transfusion-transmissible infections (e.g. hepatitis B, malaria) may indirectly defer donors with microfilaremia in endemic areas.

CONCLUSION

Rare examples of transfusion-transmitted filariasis, without serious clinical effect, suggest that filariasis poses low transfusion risk. Dedicated mitigation strategies against filarial transfusion transmission are not recommended. Given endemicity in low-resource regions, priority should be on the control of filariasis with public health measures.

Onchocerciasis dynamics: modelling the effects of treatment, education and vector control

A deterministic model of onchocerciasis disease dynamics is considered in a community partitioned into compartments based on the disease status. Public health education is offered in the community during the implementation of mass treatment using ivermectin drugs. Also, larviciding and trapping strategies are implemented in the vector population with the aim of controlling population growth of black flies. We fit the model to the data to check the suitability of the model. Expressions are derived for the influence on the reproduction numbers of these strategies. Numerical results show that the dynamics of onchocerciasis and the growth of black flies are best controlled when the four strategies are implemented simultaneously. Also, the results suggest that for the elimination of the disease in the society there is a need for finding another drug which will be implemented to ineligible human as well as killing the adult worms instead of ivermectin.

Duplex Real-Time PCR Assay for Clinical Differentiation of Onchocerca lupi and Onchocerca volvulus

In the United States and Europe, human onchocerciasis is a rare disease caused by zoonotic or anthropophilic parasites in the genus Onchocerca. The zoonotic species identified in focal areas of Europe and United States is Onchocerca lupi, and Onchocerca volvulus, the anthroponotic species, may be found among people who had lived in endemic areas of Africa, the Arabian Peninsula, or Latin America. Onchocerciasis due to O. lupi is an emergent parasitic disease, with limited diagnostic methods, in addition to the lack of information on its biology, transmission, and epidemiology. Cutaneous nodules are the disease's most prevalent manifestation but lack diagnostic specificity. To address the diagnosis of onchocerciasis at reference laboratories, we developed a duplex TaqMan real-time PCR (qPCR) method, targeting the cytochrome oxidase subunit I locus which has species-specific probes to identify and differentiate O. lupi from O. volvulus. We determined the performance of the duplex with a panel of 45 samples: 11 positives for O. lupi, six for O. volvulus, five samples with negative results for Onchocerca spp., and 23 non-Onchocerca nematodes. The duplex qPCR correctly detected 10 of 11 O. lupi- and six of six O. volvulus-positive specimens. The new duplex assay allowed the simultaneous detection and discrimination of O. lupi and O. volvulus in clinical specimens, expediting and facilitating the clinical diagnosis of O. lupi in non-endemic settings where the disease is an infrequent finding.

A Rare Case of Cutaneous Onchocerciasis in North-East India, Review of Literature

Onchocerca volvulus is a spirurid nematode that mainly affects the rural poor of Sub-Saharan Africa, Yemen, and parts of Central and South America. River blindness caused by Onchocerca volvulus is considered to be the second most common infectious cause of blindness worldwide. We report a rare case of cutaneous Onchocerciasis from a non endemic area of North-East India. We could extract live adult worms from the subcutaneous lesions and also micro filariae from the skin nips. Onchocerca was confirmed based on its morphology. The patient has been subjected to therapy with ivermectin and doxycycline and is currently on regular follow up.

Getting under the birds' skin: tissue tropism of Borrelia burgdorferi s.l. in naturally and experimentally infected avian hosts

Wild birds are frequently exposed to the zoonotic tick-borne bacteria Borrelia burgdorferi sensu lato (s.l.), and some bird species act as reservoirs for some Borrelia genospecies. Studying the tropism of Borrelia in the host, how it is sequestered in different organs, and whether it is maintained in circulation and/or in the host's skin is important to understand pathogenicity, infectivity to vector ticks and reservoir competency.We evaluated tissue dissemination of Borrelia in blackbirds (Turdus merula) and great tits (Parus major), naturally and experimentally infected with Borrelia genospecies from enzootic foci. We collected both minimally invasive biological samples (feathers, skin biopsies and blood) and skin, joint, brain and visceral tissues from necropsied birds. Infectiousness of the host was evaluated through xenodiagnoses and infection rates in fed and moulted ticks. Skin biopsies were the most reliable method for assessing avian hosts' Borrelia infectiousness, which was supported by the agreement of infection status results obtained from the analysis of chin and lore skin samples from necropsied birds and of their xenodiagnostic ticks, including a significant correlation between the estimated concentration of Borrelia genome copies in the skin and the Borrelia infection rate in the xenodiagnostic ticks. This confirms a dermatropism of Borrelia garinii, B. valaisiana and B. turdi in its avian hosts. However, time elapsed from exposure to Borrelia and interaction between host species and Borrelia genospecies may affect the reliability of skin biopsies. The blood was not useful to assess infectiousness of birds, even during the period of expected maximum spirochetaemia. From the tissues sampled (foot joint, liver, spleen, heart, kidney, gut and brain), Borrelia was detected only in the gut, which could be related with infection mode, genospecies competition, genospecies-specific seasonality and/or excretion processes.

Update on parasitic dermatoses

These are cutaneous diseases caused by insects, worms, protozoa, or coelenterates which may or may not have a parasitic life. In this review the main ethological agents, clinical aspects, laboratory exams, and treatments of these dermatological diseases will be studied.

Doxycycline for the treatment of nodding syndrome (DONS); the study protocol of a phase II randomised controlled trial

BACKGROUND

Nodding syndrome is a poorly understood neurological disorder of unknown aetiology, affecting several thousand children in Africa. There has been a consistent epidemiological association with infection by the filarial parasite, Onchocerca volvulus and antibodies to leiomodin and DJ-1, cross-reacting with O.volvulus proteins, have been reported. We hypothesized that nodding syndrome is a neuro-inflammatory disorder, induced by antibodies to O.volvulus or its symbiont, Wolbachia, cross-reacting with human neuron proteins and that doxycycline, which kills Onchocerca through effects on Wolbachia, may be used as treatment.

METHODS

This will be a two-arm, double-blind, placebo-controlled, randomised phase II trial of doxycycline 100 mg daily for six weeks in 230 participants. Participants will be patients' ages≥8 years with nodding syndrome. They will receive standard of care supportive treatment. All will be hospitalised for 1-2 weeks during which time baseline measurements including clinical assessments, EEG, cognitive and laboratory testing will be performed and antiepileptic drug doses rationalised. Participants will then be randomised to either oral doxycycline (Azudox®, Kampala Pharmaceutical Industries) 100 mg daily or placebo. Treatment will be initiated in hospital and continued at home. Participants will be visited at home at 2, 4 and 6 weeks for adherence monitoring. Study outcomes will be assessed at 6, 12, 18 and 24-month visits. Analysis will be by intention to treat. The primary efficacy outcome measure will be the proportion of patients testing positive and the levels or titires of antibodies to host neuron proteins (HNPs) and/or leiomodin at 24 months. Secondary outcome measures will include effect of the intervention on seizure control, inflammatory markers, cognitive function, disease severity and quality of life.

DISCUSSION

This trial postulates that targeting O.volvulus through drugs which kill Wolbachia can modify the pathogenic processes in nodding syndrome and improve outcomes. Findings from this study are expected to substantially improve the understanding and treatment of nodding syndrome.

TRIAL REGISTRATION

Registered with clinicaltrials.gov ID: NCT02850913 on 1st August, 2016.

Neurological manifestations in Onchocerca volvulus infection: A review

Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.

PCR-coupled sequencing achieves specific diagnosis of onchocerciasis in a challenging clinical case, to underpin effective treatment and clinical management

This study demonstrates the utility of a PCR-based DNA sequencing approach to make a specific diagnosis of onchocerciasis in a returned traveller. Although a clinical diagnosis was not possible, the surgical excision of a suprascapular nodule from this patient, combined with an histological examination of this nodule and PCR-based sequencing of DNA from a nematode from this lesion solved the case. The analysis of DNA sequence data confirmed the presence of Onchocerca volvulus infection, supporting an effective treatment-clinical management strategy for the patient.

Parasitic Infections of the Skin and Subcutaneous Tissues

A variety of arthropods, protozoa, and helminths infect the skin and subcutaneous tissues and may be identified by anatomic pathologists in standard cytology and histology preparations. The specific organisms seen vary greatly with the patient's exposure history, including travel to or residence in endemic countries. Arthropods are the most commonly encountered parasites in the skin and subcutaneous tissues and include Sarcoptes scabei, Demodex species, Tunga penetrans, and myiasis-causing fly larvae. Protozoal parasites such as Leishmania may also be common in some settings. Helminths are less often seen, and include round worms (eg, Dirofilaria spp.), tapeworms (eg, Taenia solium, Spirometra spp.), and flukes (eg, Schistosoma spp.). This review covers the epidemiologic and histopathologic features of common parasitic infections of the skin and subcutaneous tissues.

Dermatological manifestations in onchocerciasis: A retrospective study of 400 imported cases

INTRODUCTION

Onchocerciasis is caused by Onchocerca volvulus and mainly leads to pruritus and skin and visual disorders, including blindness. Seventeen million people are infected in 38 countries; 31 of these are in sub-Saharan Africa, six in Latin America and one on the Arabian Peninsula. More than 99% of cases occur in sub-Saharan Africa where 120 million people are at risk of infection. Eye disorders have been well-documented; however, skin disorders have not been described accurately. The objective of our study was to describe the epidemiology, main skin manifestations and treatment of imported onchocerciasis.

MATERIAL AND METHODS

A retrospective study was thus conducted by analysing the main demographic, clinical and treatment data regarding a cohort of 400 patients attending a reference clinical unit over a 17-year period.

RESULTS

Most patients were female (55%) with mean age 37.5±16.7 years. All the migrants came from sub-Saharan countries. The most frequently occurring dermatological symptom was pruritus. Ivermectin had been used as first-line therapy and adverse reactions had been described in 11 patients (3.2%).

CONCLUSIONS

The results indicate the fact that there should be a clinical suspicion of onchocerciasis regarding immigrants from endemic areas having skin lesions compatible with the disease's profile or asymptomatic patients having eosinophilia or unexplained high IgE. Moreover, skin snips from the buttocks region were very fruitful and treatment with ivermectin was seen to be safe. This is the largest case series regarding imported onchocerciasis described up to the present time.

O-5S quantitative real-time PCR: a new diagnostic tool for laboratory confirmation of human onchocerciasis

Background

Onchocerciasis is a parasitic disease caused by the filarial nematode Onchocerca volvulus. In endemic areas, the diagnosis is commonly confirmed by microscopic examination of skin snip samples, though this technique is considered to have low sensitivity. The available melting-curve based quantitative real-time PCR (qPCR) using degenerated primers targeting the O-150 repeat of O. volvulus was considered insufficient for confirming the individual diagnosis, especially in elimination studies. This study aimed to improve detection of O. volvulus DNA in clinical samples through the development of a highly sensitive qPCR assay.

Methods

A novel hydrolysis probe based qPCR assay was designed targeting the specific sequence of the O. volvulus O-5S rRNA gene. A total of 200 clinically suspected onchocerciasis cases were included from Goma district in South-west Ethiopia, from October 2012 through May 2013. Skin snip samples were collected and subjected to microscopy, O-150 qPCR, and the novel O-5S qPCR.

Results

Among the 200 individuals, 133 patients tested positive (positivity rate of 66.5%) and 67 negative by O-5S qPCR, 74 tested positive by microscopy (37.0%) and 78 tested positive by O-150 qPCR (39.0%). Among the 133 O-5S qPCR positive individuals, microscopy and O-150 qPCR detected 55.6 and 59.4% patients, respectively, implying a higher sensitivity of O-5S qPCR than microscopy and O-150 qPCR. None of the 67 individuals who tested negative by O-5S qPCR tested positive by microscopy or O-150 qPCR, implying 100% specificity of the newly designed O-5S qPCR assay.

Conclusions

The novel O-5S qPCR assay is more sensitive than both microscopic examination and the existing O-150 qPCR for the detection of O. volvulus from skin snip samples. The newly designed assay is an important step towards appropriate individual diagnosis and control of onchocerciasis.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2382-3) contains supplementary material, which is available to authorized users.

Ivermectin induced Steven-Johnsons syndrome: case report

BACKGROUND

Stevens-Johnson syndrome is one of the manifestations of mucocutaneous adverse drug reactions. Although antimicrobials are responsible for greater than 50% of these adverse drug reactions, there is no documented case implicating ivermectin as the culprit. A 38 year old adult Cameroonian male presented to our health facility with facial rash, painful oral sores, black eschars on lips and red tearing eyes 3 days following ingestion of ivermectin received during a nationwide anti-filarial campaign. He had no known chronic illness, no known allergies and was not on any medications prior to the campaign. Physical examination revealed discharging erythematous eyes, crusted and blister-like lesions with cracks on his lips and oral mucosa. His laboratory tests were unremarkable but for a positive Human Immunodeficiency Virus (HIV) test. A diagnosis of Ivermectin induced Stevens-Johnson syndrome in a newly diagnosed HIV patient was made. The patient was managed with supportive therapy and the evolution thereafter was favourable.

CONCLUSION

Stevens-Johnson syndrome is a potential side effect of ivermectin and susceptibility to this adverse effect may be increased in HIV infection.

Examining the role of macrolides and host immunity in combatting filarial parasites

Macrocyclic lactones (MLs), specifically the avermectins and milbemycins, are known for their effectiveness against a broad spectrum of disease-causing nematodes and arthropods in humans and animals. In most nematodes, drugs in this class induce paralysis, resulting in starvation, impaired ability to remain associated with their anatomical environment, and death of all life stages. Initially, this was also thought to be the ML mode of action against filarial nematodes, but researchers have not been able to validate these characteristic effects of immobilization/starvation of MLs in vitro, even at higher doses than are possible in vivo. Relatively recently, ML receptor sites exclusively located proximate to the excretory-secretory (ES) apparatus were identified in Brugia malayi microfilaria and an ML-induced suppression of secretory protein release by B. malayi microfilariae was demonstrated in vitro. It is hypothesized here that suppression of these ES proteins prevents the filarial worm from interfering with the host's complement cascade, reducing the ability of the parasite to evade the immune system. Live microfilariae and/or larvae, thus exposed, are attacked and presented to the host's innate immune mechanisms and are ultimately killed by the immune response, not the ML drug. These live, exposed filarial worms stimulate development of innate, cellular and humoral immune responses that when properly stimulated, are capable of clearing all larvae or microfilariae present in the host, regardless of their individual sensitivity to MLs. Additional research in this area can be expected to improve our understanding of the relationships among filarial worms, MLs, and the host immune system, which likely would have implications in filarial disease management in humans and animals.

Is imported onchocerciasis a truly rare entity? Case report and review of the literature

BACKGROUND

Onchocerciasis is endemic in a number of tropical countries in Africa and South America, and it is occasionally diagnosed as an imported disease in non-endemic areas.

METHODS

We describe the case of an African migrant with long-lasting pruritus and a cutaneous nodule who was diagnosed with onchocerciasis after nodulectomy, and review the medical literature regarding imported cases of onchocerciasis in the period 1994-2014.

RESULTS

Twenty-nine cases of onchocerciasis diagnosed in migrants from endemic countries, and in expatriates and travellers from non-endemic areas were retrieved. They were predominantly males (73.3%), had a median age of 37 years (two were aged <15 years), and acquired the diseases in sub-Saharan Africa, most frequently in Cameroon (43.3%). Diagnosis of onchocercosis was proven in 73.3% of patients. The most frequent clinical manifestations in these and our own patient were pruritus (23/30, 76.7%), unilateral leg or forearm swelling (13/30, 43.3%) and rash (12/30, 40.0%), whereas only two (6.9%) complained of eye symptoms. Eosinophilia was observed in almost all of the patients (92.0%), with median counts of 2915/μL among migrants and 1960/μL among travellers/expatriates. Eighteen patients underwent a skin snip biopsy, which was positive in 10 cases (55.5%); in the other 13 patients the parasite was directly demonstrated by means of a skin or nodule biopsy (n = 5), nodulectomy (n = 5) or slit lamp examination (n = 3). Eighteen received ivermectin, alone, and seven ivermectin combined with diethylcarbamazine or doxycycline. Outcome details were available for only 14 patients, all of whom were asymptomatic after a median follow-up of 10 months (range 1-48).

CONCLUSIONS

Onchocerciasis is a neglected tropical disease whose subtle and non-specific features may lead to under-diagnosis or underreporting in non-endemic areas. Physicians should consider this tropical disease when caring for migrants and travellers/expatriates with pruritus, skin lesions and eosinophilia.

An appraisal of the neglected tropical diseases control program in Cameroon: the case of the national program against onchocerciasis

Background

Onchocerciasis is a severe parasitic infestation which causes disabling skin and subcutaneous tissue changes. Current global estimates suggest that it accounts for 1135.7 disability adjusted life years (DALYs) per 100,000 population. The disease is endemic in many African countries including Cameroon, probably suggesting that the current health policies are inadequate to achieve eradication of the disease. We aimed to appraise the current Onchocerciasis control program in Cameroon in the context of existing literature.

Methods

We carried out a MEDLINE search via PubMed to source for articles on Onchocerciasis in Cameroon.

Results

Our appraisal of the literature suggests that Onchocerciasis poses a significant health and economic burden in Cameroon. A composite of factors contribute to the challenge of containing and eradicating Onchocerciasis in Cameroon and include: continuous transmission of the disease; non-compliance to mass drug administration; inability of health care providers (HCPs) to adequately diagnose the disease; limited access of most individuals in endemic zones to annual preventive chemotherapy and inadequate population education on simple and practical measures to prevent the disease. More robust population-based epidemiologic studies are needed to better quantify the current disease burden and consequently guide intervention strategies for complete disease eradication.

Conclusion

Onchocerciasis is still a neglected tropical disease (NTD) in Cameroon and urgently demands a need for intensification and probably modification of some strategies in the current onchocerciasis elimination program. Control of the disease will contribute to achievement of the corresponding Sustainable Development Goals (SDGs) quota.

[Clinical approach to imported eosinophilia]

Eosinophilia is a common finding in international travelers and immigrants, being an helmintic infection its main etiology. The positive predictive value of eosinophilia for an helmintosis is low in travellers. Eosinophilia may be an incidental finding, or symptomatic, and it represents a clinical challenge due to the low sensitivity and specificity of direct and indirect parasitological diagnostic tests, respectively. It requires a structured approach based on geographical areas, environmental exposures and behavioral risks, and associated symptoms. The initial assessment should include a comprehensive and tailored anamnesis and physical examination, basic laboratory tests, a complete parasitological examination of stool samples and a Strongyloides stercoralis serology, supplemented with other explorations guided by epidemiological and clinical suspicion. Empiric treatment with albendazole and/or ivermectin (plus praziquantel if risk of schistosomiasis) is an option for unidentified persistent eosinophilia after study, and in persons in whom a proper assessment or follow-up can not be assured. In patients at risk for estrongiloidosis who are candidates for immunosuppressive therapies, it is indicated a prior screening and treatment to prevent a future hyperinfestation syndrome.

Honoring antiparasitics: The 2015 Nobel Prize in Physiology or Medicine

Protozoa and helminths are the two main groups that cause parasitic diseases with a broad spectrum of clinical symptoms. Protozoa are unicellular organisms like the malaria parasite Plasmodium, which is responsible for the majority of deaths associated with parasitic infections. Helminths are alternative parasites that can produce debilitating diseases in hosts, some of which result in chronic infections. The discovery of effective therapeutic drugs is the key to improving health in regions of poverty and poor sanitation where these parasites usually occur. It is very encouraging that the 2015 Nobel Prize in Physiology or Medicine was awarded to Youyou Tu as well as William C. Campbell and Satoshi Õmura for their considerable contributions in discovering artemisinin and avermectin, respectively. Both drugs revolutionized therapies for filariasis and malaria, significantly reducing by large percentages their morbidity and mortality.

Is nodding syndrome an Onchocerca volvulus-induced neuroinflammatory disorder? Uganda's story of research in understanding the disease

Nodding syndrome is a devastating neurological disorder, mostly affecting children in eastern Africa. An estimated 10000 children are affected. Uganda, one of the most affected countries, set out to systematically investigate the disease and develop interventions for it. On December 21, 2015, the Ministry of Health held a meeting with community leaders from the affected areas to disseminate the results of the investigations made to date. This article summarizes the presentation and shares the story of studies into this peculiar disease. It also shares the results of preliminary studies on its pathogenesis and puts into perspective an upcoming treatment intervention. Clinical and electrophysiological studies have demonstrated nodding syndrome to be a complex epilepsy disorder. A definitive aetiological agent has not been established, but in agreement with other affected countries, a consistent epidemiological association has been demonstrated with infection by Onchocerca volvulus. Preliminary studies of its pathogenesis suggest that nodding syndrome may be a neuroinflammatory disorder, possibly induced by antibodies to O. volvulus cross-reacting with neuron proteins. Histological examination of post-mortem brains has shown some yet to be characterized polarizable material in the majority of specimens. Studies to confirm these observations and a clinical trial are planned for 2016.

Cutaneous onchocerciasis in Dumbu, a pastoral area in the North-West region of Cameroon: diagnostic challenge and socio-economic implications

Onchocerciasis is a severe parasitic infestation caused by Onchocerca volvulus which causes disabling skin and subcutaneous tissue changes and ultimately leads to blindness. It has a huge public health impact due to its socioeconomic burden and the vast number of people it affects in developing countries. In this case, a 60 years old woman was encountered with leopard skin like changes, rashes and pruritus on the left leg; which had been managed as cutaneous mycosis for over a period of 8 years. A diagnosis of onchocerciasis was finally made after a skin snip identified onchocercal microfilariae. The above case shows that onchocerciasis is still a neglected tropical disease (NTD) in Cameroon. This emphasizes the need for more expansive outreach programs in remote areas in Cameroon, a change in health policies to ensure the eradication of this disabling disease and health promotion amongst vulnerable populations.

Litomosoides sigmodontis: a jird urine metabolome study

The neglected tropical disease onchocerciasis affects more than 35 million people worldwide with over 95% in Africa. Disease infection initiates from the filarial parasitic nematode Onchocerca volvulus, which is transmitted by the blackfly vector Simulium sp. carrying infectious L3 larvae. New treatments and diagnostics are required to eradicate this parasitic disease. Herein, we describe that a previously discovered biomarker for onchocerciasis, N-acetyltyramine-O-glucuronide (NATOG) is also present in urine samples of jirds infected with the onchocerciasis model nematode Litomosoides sigmodontis. Increased NATOG values paralleled a progressing infection and demonstrated that quantification of NATOG in this rodent model can be utilized to track its infectivity. Moreover, our findings suggest how NATOG monitoring may be used for evaluating potential drug candidates.

Financial and Economic Costs of the Elimination and Eradication of Onchocerciasis (River Blindness) in Africa

BACKGROUND

Onchocerciasis (river blindness) is a parasitic disease transmitted by blackflies. Symptoms include severe itching, skin lesions, and vision impairment including blindness. More than 99% of all cases are concentrated in sub-Saharan Africa. Fortunately, vector control and community-directed treatment with ivermectin have significantly decreased morbidity, and the treatment goal is shifting from control to elimination in Africa.

METHODS

We estimated financial resources and societal opportunity costs associated with scaling up community-directed treatment with ivermectin and implementing surveillance and response systems in endemic African regions for alternative treatment goals--control, elimination, and eradication. We used a micro-costing approach that allows adjustment for time-variant resource utilization and for the heterogeneity in the demographic, epidemiological, and political situation.

RESULTS

The elimination and eradication scenarios, which include scaling up treatments to hypo-endemic and operationally challenging areas at the latest by 2021 and implementing intensive surveillance, would allow savings of $1.5 billion and $1.6 billion over 2013-2045 as compared to the control scenario. Although the elimination and eradication scenarios would require higher surveillance costs ($215 million and $242 million) than the control scenario ($47 million), intensive surveillance would enable treatments to be safely stopped earlier, thereby saving unnecessary costs for prolonged treatments as in the control scenario lacking such surveillance and response systems.

CONCLUSIONS

The elimination and eradication of onchocerciasis are predicted to allow substantial cost-savings in the long run. To realize cost-savings, policymakers should keep empowering community volunteers, and pharmaceutical companies would need to continue drug donation. To sustain high surveillance costs required for elimination and eradication, endemic countries would need to enhance their domestic funding capacity. Societal and political will would be critical to sustaining all of these efforts in the long term.

A community-based cross-sectional study of the epidemiology of onchocerciasis in unmapped villages for community directed treatment with ivermectin in Jimma Zone, southwestern Ethiopia

BACKGROUND

Human onchocerciasis is a neglected tropical parasitic disease caused by Onchocerca volvulus (O. volvulus) that may result in devastating skin and eye morbidity. Even though the disease is targeted for elimination, there was little or no information on the level of onchocerciasis endemicity for implementation of community directed treatment with ivermectin (CDTI) in the current study area. Thus, this study aimed at investigating the epidemiology of onchocerciasis and the level of awareness towards the disease among communities living close to CDTI area, Jimma Zone, southwestern Ethiopia.

METHODS

A community based cross-sectional study was conducted from April 23 to May 22, 2012. Data on socio-demographic characteristics, knowledge, attitude and practice towards onchocerciasis were collected using semi-structured questionnaires. Clinical examination was undertaken for onchocercal skin diseases by experienced health professionals. Moreover, two skin snip samples were collected from the right and left gluteal folds. Study participants found positive for O. volvulus infection during the study were treated individually with standard dose of ivermectin as per WHO guideline.

RESULTS

The overall prevalence of O. volvulus infection was 22.5 % while the prevalence of onchocercal skin diseases was 29.8 %. The community microfilarial (mf) load was 5.70 mf per skin snip. Age, sex, educational status, occupation and duration of stay in the villages showed significant association with onchocerciasis (P < 0.05). But sex (OR = 0.565, 95 % CI = 0.335, 0.952), educational status (OR = 0.545, 95 % CI = 0.310, 0.958) and duration of stay in the village (OR = 5.933, 95 % CI = 1.017, 34.626) were the independent predictors for O. volvulus infection. Three hundred eighty eight (88.2 %) of the study participants reported that they didn't know about onchocerciasis.

CONCLUSIONS

There was moderate prevalence of onchocercal infection and onchocercial skin diseases (OSD) in the study area. Result of this study may suggest that the endemicity level of onchocerciasis in the study area was mesoendemic. Hence, intervention using ivermectin treatment should be implemented to reduce the burden of onchocerciasis. Since the majorities of the population had poor knowledge, attitude and practice towards onchocerciasis, inclusion of health education in the intervention package is crucial.

Conventional parasitology and DNA-based diagnostic methods for onchocerciasis elimination programmes

Commonly used methods for diagnosing Onchocerca volvulus infections (microscopic detection of microfilariae in skin snips and nodule palpation) are insensitive. Improved methods are needed for monitoring and evaluation of onchocerciasis elimination programmes and for clinical diagnosis of individual patients. A sensitive probe-based qPCR assay was developed for detecting O. volvulus DNA, and this was tested with samples collected from an endemic area in eastern Côte d'Ivoire. The new test was evaluated with dried skin snip pairs from 369 subjects and compared to routine skin snip microscopy and nodule palpation results from the same individuals. Onchocerciasis prevalence for these samples by qPCR, skin snip microscopy, and nodule palpation were 56.9%, 26.0%, and 37.9%, respectively. Furthermore, the combination of all three tests produced an infection prevalence of 72.9%, which was significantly higher than 53.1% detected by microscopy plus nodule palpation without qPCR. However, the qPCR assay was negative for 54 of 229 individuals with palpable nodules. qPCR could be a useful tool for detecting residual O. volvulus infections in human populations as prevalence decreases in areas following community-directed treatment with ivermectin.

Control, elimination, and eradication of river blindness: scenarios, timelines, and ivermectin treatment needs in Africa

River blindness (onchocerciasis) causes severe itching, skin lesions, and vision impairment including blindness. More than 99% of all current cases are found in sub-Saharan Africa. Fortunately, vector control and community-directed treatment with ivermectin have significantly reduced morbidity. Studies in Mali and Senegal proved the feasibility of elimination with ivermectin administration. The treatment goal is shifting from control to elimination in endemic African regions. Given limited resources, national and global policymakers need a rigorous analysis comparing investment options. For this, we developed scenarios for alternative treatment goals and compared treatment timelines and drug needs between the scenarios. Control, elimination, and eradication scenarios were developed with reference to current standard practices, large-scale studies, and historical data. For each scenario, the timeline when treatment is expected to stop at country level was predicted using a dynamical transmission model, and ivermectin treatment needs were predicted based on population in endemic areas, treatment coverage data, and the frequency of community-directed treatment. The control scenario requires community-directed treatment with ivermectin beyond 2045 with around 2.63 billion treatments over 2013–2045; the elimination scenario, until 2028 in areas where feasible, but beyond 2045 in countries with operational challenges, around 1.15 billion treatments; and the eradication scenario, lasting until 2040, around 1.30 billion treatments. The eradication scenario is the most favorable in terms of the timeline of the intervention phase and treatment needs. For its realization, strong health systems and political will are required to overcome epidemiological and political challenges.

River blindness (onchocerciasis) is transmitted by blackflies and causes severe itching, skin lesions, and vision impairment including blindness. More than 99% of all current cases are found in sub-Saharan Africa where the disease has historically hindered socioeconomic development in endemic areas. The treatment goal is shifting from control to elimination in Africa as morbidity has significantly decreased through vector control and community-directed treatment with ivermectin. Studies in Mali and Senegal proved that elimination is feasible with ivermectin administration. Given limited resources, national and global policymakers need a rigorous analysis of investment options from epidemiological, economic, and societal aspects. For this, we developed control, elimination, and eradication scenarios and compared treatment timelines and drug needs over the next 30 years. We found that the elimination and eradication scenarios would require a shorter treatment phase and a smaller amount of ivermectin than the control scenario, mainly because community-directed treatment with ivermectin could be ended earlier thanks to regular active surveillance.

Detection of circulating parasite-derived microRNAs in filarial infections

Filarial nematodes cause chronic and profoundly debilitating diseases in both humans and animals. Applications of novel technology are providing unprecedented opportunities to improve diagnosis and our understanding of the molecular basis for host-parasite interactions. As a first step, we investigated the presence of circulating miRNAs released by filarial nematodes into the host bloodstream. miRNA deep-sequencing combined with bioinformatics revealed over 200 mature miRNA sequences of potential nematode origin in Dirofilaria immitis-infected dog plasma in two independent analyses, and 21 in Onchocerca volvulus-infected human serum. Total RNA obtained from D. immitis-infected dog plasma was subjected to stem-loop RT-qPCR assays targeting two detected miRNA candidates, miR-71 and miR-34. Additionally, Brugia pahangi-infected dog samples were included in the analysis, as these miRNAs were previously detected in extracts prepared from this species. The presence of miR-71 and miR-34 discriminated infected samples (both species) from uninfected samples, in which no specific miRNA amplification occurred. However, absolute miRNA copy numbers were not significantly correlated with microfilaraemia for either parasite. This may be due to the imprecision of mf counts to estimate infection intensity or to miRNA contributions from the unknown number of adult worms present. Nonetheless, parasite-derived circulating miRNAs are found in plasma or serum even for those species that do not live in the bloodstream.

Filarial parasites commonly infect humans and animals, especially in tropical settings. The strongly debilitating panel of diseases they cause in humans contributes to an entrenched cycle of poverty. For efficient treatment strategies, reliable diagnostic tests are necessary. We investigated the potential of parasite-derived microRNAs (miRNAs; short non-coding RNA molecules present in eukaryotes) as biomarkers of infection. Using deep-sequencing technologies and bioinformatics, we identified over two-hundred mature miRNA candidates of nematode origin in plasma from Dirofilaria immitis-infected dogs. Similarly, we discovered twenty-one miRNA candidates predicted to be released by Onchocerca volvulus in infected human sera. We developed two RT-qPCR assays for the detection of D. immitis miR-71 and miR-34 in dog plasma that discriminated infected from uninfected samples. We demonstrated the presence of filarial miRNAs in host blood, regardless of localization in their respective hosts, and suggest that they are suitable targets for detection by RT-qPCR.

A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a)

The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.

The ClpP peptidase of Wolbachia endobacteria is a novel target for drug development against filarial infections

BACKGROUND

Filarial infections causing lymphatic filariasis or onchocerciasis (river blindness) can be treated with antibiotics (e.g. doxycycline) targeting the essential endosymbiotic Wolbachia bacteria. The depletion of Wolbachia inhibits worm development and causes worm death. Available antibiotics have restrictions for use in children and pregnant or breastfeeding women. Therefore, alternative antibiotics are needed that can be given to all members of the population and that are active with a shorter therapy time. Antibiotics of the acyldepsipeptide class have been shown to inhibit the growth of bacteria by overactivating the peptidase ClpP. The novel mode of action of this class of antibiotics could lead to faster killing of intracellular bacteria.

OBJECTIVES

To characterize acyldepsipeptide activity against the Wolbachia ClpP.

METHODS

The activity of acyldepsipeptides was investigated against Wolbachia in vitro in insect cells and also against worms in culture. In addition, structural effects were investigated by fluorescence microscopy and electron microscopy. The activity of ClpP was also investigated in vitro.

RESULTS

We show that acyldepsipeptides are active against recombinant Wolbachia ClpP and endobacteria resident within insect cells in vitro, and some derivatives were also active against filarial worms in culture. As a consequence of treatment, the worms became immotile and died, the latter confirmed by a viability assay.

CONCLUSIONS

The mode of action of the acyldepsipeptides in Wolbachia is the dysregulation of ClpP, causing the uncontrolled degradation of proteins, including the cell division protein FtsZ. Our results demonstrate that wolbachial ClpP is a target for further antifilarial antibiotic discovery.

Analytical profile of moxidectin

Moxidectin or F28249α is a potent endectocide and semisynthetic methoxime derivative of naturally occurring nemadectin. It is well known for the novel mode of action against a broad range of nematode and anthropod animal parasites. In this work, physicochemical and pharmaceutical aspects of moxidectin are described including stability, semisynthesis, purification processes, formulation compositions, impurities, and degradation pathways. Additional experiments such as DSC, XRD, and CHN analysis were carried out to complete the profile of moxidectin. The importance of safety and quality of drug substances was highlighted by chronological developments involving moxidectin and its analogues. The information gathered from the literature was used to trace the origins of moxidectin-related substances presented in the European Pharmacopeia (EP) compendial monograph. During the review, it was noticed that majority of impurities presented in the EP does not have any potential to increase with time in drug substance or formulated products; therefore, they do not require monitoring during stability studies. This also showed the requirement for further characterization of the impurities observed during long-term storage and development of stability indicating methods distinguishing between process impurities and the true degradation products. Furthermore, the stability of moxidectin in formulations is also reviewed in conjunction with known degradation routes and innovative ways to formulate products that are stable and effective at intended shelf life.

Predictive and epidemiologic modeling of the spatial risk of human onchocerciasis using biophysical factors: a case study of Ghana and Burundi

Although recent efforts taken have substantially contained human onchocerciasis in many African countries, published reports indicate a recrudescence of the disease. To understand this problem, biophysical factors that favor the establishment of human onchocerciasis in Ghana and Burundi-countries identified as threat locations of recrudescence for neighboring countries-were analyzed. Data pertaining to the prevalence of human onchocerciasis in both countries was obtained from published sources. Findings in this study suggest that there was a gradient in prevalence of onchocerciasis in geographic locations near the water streams. The predictive models suggest that rainfall, humidity, and elevation were statistically significant for Burundi data while in Ghana, only the effect of elevation was highly significant (p<0.0001). In 2010, the estimated at-risk population was 4,817,280 people (19.75% of the total population) and 522,773 people (6.23% of the total population) in Ghana and Burundi, respectively. Findings can help in the effective design of preventive control measures.