Multimodal biomarker discovery for active Onchocerca volvulus infection

The neglected tropical disease onchocerciasis, or river blindness, is caused by infection with the filarial nematode Onchocerca volvulus. Current estimates indicate that 17 million people are infected worldwide, the majority of them living in Africa. Today there are no non-invasive tests available that can detect ongoing infection, and that can be used for effective monitoring of elimination programs. In addition, to enable pharmacodynamic studies with novel macrofilaricide drug candidates, surrogate endpoints and efficacy biomarkers are needed but are non-existent. We describe the use of a multimodal untargeted mass spectrometry-based approach (metabolomics and lipidomics) to identify onchocerciasis-associated metabolites in urine and plasma, and of specific lipid features in plasma of infected individuals (O. volvulus infected cases: 68 individuals with palpable nodules; lymphatic filariasis cases: 8 individuals; non-endemic controls: 20 individuals). This work resulted in the identification of elevated concentrations of the plasma metabolites inosine and hypoxanthine as biomarkers for filarial infection, and of the urine metabolite cis-cinnamoylglycine (CCG) as biomarker for O. volvulus. During the targeted validation study, metabolite-specific cutoffs were determined (inosine: 34.2 ng/ml; hypoxanthine: 1380 ng/ml; CCG: 29.7 ng/ml) and sensitivity and specificity profiles were established. Subsequent evaluation of these biomarkers in a non-endemic population from a different geographical region invalidated the urine metabolite CCG as biomarker for O. volvulus. The plasma metabolites inosine and hypoxanthine were confirmed as biomarkers for filarial infection. With the availability of targeted LC-MS procedures, the full potential of these 2 biomarkers in macrofilaricide clinical trials, MDA efficacy surveys, and epidemiological transmission studies can be investigated.

Surveillance of canine filarial infection in Ulaanbaatar city

In this study, totally 180 stray and domestic dogs in 6 districts of Ulaanbaatar city, Mongolia were tested for infection with microfilariae. Microfilariae were found in peripheral blood smears of 2 out of 180 (1.1%) tested dogs. In contrast, out of tested dogs, 2.2% were found to be infected by microfilariae by the Knott’s method. Higher prevalence was found in stray dogs (10%) than in domestic dogs. Canine filarosis present and it might be constituted an important health problem to dogs and humans in Mongolia. Thus, it would be useful to apply prevention measures to control filarial infection in the canine population of Ulaanbaatar city. Улаанбаатар хотын нохойноос филарозын халдварыг илрүүлэх тандан судалгаа Филароз нь шумуулаар дамжин халдварладаг нематодоор үүсгэгддэг бөгөөд хүн, мал, амьтны биед удаан хугацааны турш шимэгчилж улмаар үхэлд хүргэдэг хор хөнөөлтэй өвчин юм. Бид Улаанбаатар хотын нохойнд филарозын тандан судалгаа хийх зорилгоор 6 дүүргийн 180 гэрийн тэжээвэр болон золбин нохойг санамсаргүй түүврийн аргаар сонгон авч шинжилгээнд хамрууллаа. Кноттын арга ба цусны түрхэцийн шинжилгээгээр Улаанбаатар хотын нохой филарозын халдвар (1.1–3.9%)–тай болохыг тогтоолоо. Ялангуяа хүн амын төвлөрөл ихтэй хот суурин газрын золбин нохой филарозын халдвартай (10%) байгаа нь гэрийн тэжээвэр нохой төдийгүй хүнд халдвар тархах эрсдлийг бий болгож байна. Цаашид оношийг молекул биологийн аргаар баталгаажуулж, микрофилариагийн төрөл зүйл, удам зүйн хамаарлын нарийвчилсан судалгааг хийх шаардлагатай юм. Түлхүүр үг: нематод, микрофилариа, кноттын арга, түрхэц

Membranoproliferative glomerulonephritis: A rare presentation of occult filariasis

Parasitic infections do not usually present with rapidly progressive renal failure but can provoke glomerular lesions which are mostly proliferative. In filarial infection, glomerular involvement is usually mild and transient, and presentation with renal failure is rare. We report occult filariasis presenting as rapidly progressive renal failure due to immune-complex mediated membranoproliferative glomerulonephritis. Our patient responded to treatment with diethylcarbamazine and a short course of steroid. This case highlights the importance of thorough workup to identify the cause and consideration of filariasis in an endemic area.

Investigation on the Prevalence of Canine Microfilaremia in Thailand Using a Novel Microfluidic Device in Combination with Real-Time PCR

We conducted a survey of canine microfilaraemia in 768 dogs in Chanthaburi, Samut Sakhon, and Narathiwat provinces of Thailand using a novel semi-automated, microfluidic device that is easy and rapid to perform. Microfilariae species were identified using High Resolution Melting real-time PCR (HRM real-time PCR). The prevalence of canine microfilaremia was 16.2% (45/278) in Chanthaburi and 5.5% (12/217) in Samut Sakhon. The prevalence of canine microfilaremia in Narathiwat was 22.7% (67/273). Brugia pahangi and Dirofilaria immitis were the predominant species of filariae found in the infected dogs from Chanthaburi and Narathiwat, respectively. The low prevalence of canine microfilaremia of Samut Sakhon may reflect the success of the Soi Dog foundation’s efforts and the establishment of veterinary control programs. An effective disease control and prevention strategies is needed in Chanthaburi and Narathiwat to reduce the risks of zoonotic transmission of the parasites. An appropriate drug treatment should be given to infected dogs and prophylactic drugs are suggested to be given to dogs age ≤1-year-old to prevent filarial infection. The novel microfluidic device could be implemented for surveillance of filariae infection in other animals.

Strategies to Control Human Lymphatic Filarial Infection: Tweaking Host’s Immune System

Human lymphatic filariasis (LF), a parasitic infection caused by the nematodes Wuchereria bancrofti, Brugia malayi and B. timori, and transmitted by mosquito, results in a debilitating disease commonly identified as ‘elephantiasis’. LF affects millions of people in India and several other tropical and sub-tropical countries imposing a huge economic burden on governments due to disability associated loss of man-hours and for disease management. Efforts to control the infection by WHO’s mass drug administration (MDA) strategy using three antifilarials diethylcarbamazine, albendazole and ivermectin are only partly successful and therefore, there is an immediate need for alternative strategies. Some of the alternative strategies being explored in laboratories are: enhancing the immune competence of host by immunomodulation, combining immunomodulation with antifilarials, identifying immunoprophylactic parasite molecules (vaccine candidates) and identifying parasite molecules that can be potential drug targets. This review focuses on the advances made in this direction.

Assessing the Presence of Wuchereria bancrofti Infections in Vectors Using Xenomonitoring in Lymphatic Filariasis Endemic Districts in Ghana

Mass drug administration (MDA) is the current mainstay to interrupt the transmission of lymphatic filariasis. To monitor whether MDA is effective and transmission of lymphatic filariasis indeed has been interrupted, rigorous surveillance is required. Assessment of transmission by programme managers is usually done via serology. New research suggests that xenomonitoring holds promise for determining the success of lymphatic filariasis interventions. The objective of this study was to assess Wuchereria bancrofti infection in mosquitoes as a post-MDA surveillance tool using xenomonitoring. The study was carried out in four districts of Ghana; Ahanta West, Mpohor, Kassena Nankana West and Bongo. A suite of mosquito sampling methods was employed, including human landing collections, pyrethrum spray catches and window exit traps. Infection of W. bancrofti in mosquitoes was determined using dissection, conventional and real-time polymerase chain reaction and loop mediated isothermal amplification assays. Aedes, Anopheles coustani, An. gambiae, An. pharoensis, Culex and Mansonia mosquitoes were sampled in each of the four study districts. The dissected mosquitoes were positive for filarial infection using molecular assays. Dissected An. melas mosquitoes from Ahanta West district were the only species found positive for filarial parasites. We conclude that whilst samples extracted with Trizol reagent did not show any positives, molecular methods should still be considered for monitoring and surveillance of lymphatic filariasis transmission.