Lymphatic Filariae Research Articles

A Mini Review On the Analytical Methods for Individual and Drug Combinations Administered in Mass Drug Administration for Lymphatic Filariasis

Abstract: The NTDs (Neglected Tropical Diseases) are the group of diseases considered the diseases of the poor. Lymphatic Filariae (LF) is one of the category that is prevalent mostly in 47 countries and around 863 million people are under threat from this category of disease. A program named Global Programme to Eliminate Lymphatic Filariasis (GPELF) was initiated by WHO (World Health Organisation) in 1998, with the aim of eliminating LF by 2020. The main role of GPELF was to initiate measures to stop the spread of disease and to control the suffering caused by disease to the patients. For controlling the spread of disease, mass drug administration (MDA) was initiated where the drug or their combinations were administered annually or as and when required. This initiative was Alternating Mass Drug Administration Regimens to Eliminate Lymphatic Filariasis. The recommendations depended on the causative organism and co-endemicity of LF with other filarial diseases. The drug recommendations by WHO for MDA were; for areas with LF and loiasis, albendazole in a dose of 400 mg twice a year; for areas with onchocerciasis and LF, ivermectin in a dose of 200 mcg/kg along with albendazole 400 mg; for areas without onchocerciasis diethylcarbamazine citrate (DEC) in a dose of 6 mg/kg combined with albendazole in dose 400 mg. The three-drug combination was also recommended in some cases where onchocerciasis was not prevalent with LF. Many clinical trials also started for comparing one, two, and even three-drug combinations. A document to streamline the use of these drugs for LF was also issued by WHO in 2017 with the name Alternating mass drug administration regimens to eliminate lymphatic filariasis. The achievement with these regimens, till 2020 was that 80 percent of countries endemic to LF have achieved elimination of this disease. Further, to achieve better elimination in other countries a road map for 2020-2030 is now in being. The analytical methods for individual drugs as they are very old drugs were available and some of the methods for combination are also there mostly involving High- Performance Liquid Chromatography (HPLC) with different types of detecting combinations. These methods are given for detection in various clinical trials or used as an analytical method for the determination of drug(s) in dosage forms.

Harnessing Immune Evasion Strategy of Lymphatic Filariae: A Therapeutic Approach against Inflammatory and Infective Pathology

Human lymphatic filariae have evolved numerous immune evasion strategies to secure their long-term survival in a host. These strategies include regulation of pattern recognition receptors, mimicry with host glycans and immune molecules, manipulation of innate and adaptive immune cells, induction of apoptosis in effector immune cells, and neutralization of free radicals. This creates an anti-inflammatory and immunoregulatory milieu in the host: a modified Th2 immune response. Therefore, targeting filarial immunomodulators and manipulating the filariae-driven immune system against the filariae can be a potential therapeutic and prophylactic strategy. Filariae-derived immunosuppression can also be exploited to treat other inflammatory diseases and immunopathologic states of parasitic diseases, such as cerebral malaria, and to prevent leishmaniasis. This paper reviews immunomodulatory mechanisms acquired by these filariae for their own survival and their potential application in the development of novel therapeutic approaches against parasitic and inflammatory diseases. Insight into the intricate network of host immune-parasite interactions would aid in the development of effective immune-therapeutic options for both infectious and immune-pathological diseases.

A mouse infection model and long-term lymphatic endothelium co-culture system to evaluate drugs against adult Brugia malayi.

The development of new drugs targeting adult-stage lymphatic filarial nematodes is hindered by the lack of a robust long-term in vitro culture model. Testing potential direct-acting and anti-Wolbachia therapeutic candidates against adult lymphatic filariae in vitro requires their propagation via chronic infection of gerbils. We evaluated Brugia malayi parasite burden data from male Mongolian gerbils compared with two immune-deficient mouse strains highly susceptible to B. malayi: CB.17 Severe-Combined Immmuno-Deficient (SCID) and interleukin-4 receptor alpha, interleukin-5 double knockout (IL-4Rα-/-IL-5-/-) mice. Adult worms generated in IL-4Rα-/-IL-5-/- mice were tested with different feeder cells (human embryonic kidney cells, human adult dermal lymphatic endothelial cells and human THP-1 monocyte differentiated macrophages) and comparative cell-free conditions to optimise and validate a long-term in vitro culture system. Cultured parasites were compared against those isolated from mice using motility scoring, metabolic viability assay (MTT), ex vivo microfilariae release assay and Wolbachia content by qPCR. A selected culture system was validated as a drug screen using reference anti-Wolbachia (doxycycline, ABBV-4083 / flubentylosin) or direct-acting compounds (flubendazole, suramin). BALB/c IL-4Rα-/-IL-5-/- or CB.17 SCID mice were superior to Mongolian gerbils in generating adult worms and supporting in vivo persistence for periods of up to 52 weeks. Adult females retrieved from BALB/c IL-4Rα-/-IL-5-/- mice could be cultured for up to 21 days in the presence of a lymphatic endothelial cell co-culture system with comparable motility, metabolic activity and Wolbachia titres to those maintained in vivo. Drug studies confirmed significant Wolbachia depletions or direct macrofilaricidal activities could be discerned when female B. malayi were cultured for 14 days. We therefore demonstrate a novel methodology to generate adult B. malayi in vivo and accurately evaluate drug efficacy ex vivo which may be adopted for drug screening with the dual benefit of reducing overall animal use and improving anti-filarial drug development.

Semi-Automated Microfluidic Device Combined with a MiniPCR-Duplex Lateral Flow Dipstick for Screening and Visual Species Identification of Lymphatic Filariae.

Lymphatic filariasis (LF) is a leading cause of permanent disability worldwide that has been listed as a neglected tropical disease by the World Health Organization. Significant progress made by the Global Program to Eliminate Lymphatic Filariasis (GPELF) has led to a substantial decline in the population of the worm that causes LF infection. Diagnostic assays capable of detecting low levels of parasite presence are needed to diagnose LF. There is also a need for new tools that can be used in areas where multiple filarial species are coendemic and for mass screening or for use in a point-of-care setting. In the present study, we applied our previously developed semi-automated microfluidic device in combination with our recently developed mini polymerase chain reaction (miniPCR) with a duplex lateral flow dipstick (DLFD) (miniPCR-DLFD) for rapid mass screening and visual species identification of lymphatic filariae in human blood. The study samples comprised 20 Brugia malayi microfilariae (mf) positive human blood samples, 14 Wuchereria bancrofti mf positive human blood samples and 100 mf negative human blood samples. Microfilariae detection and visual species identification was performed using the microfluidic device. To identify the species of the mf trapped in the microfluidic chips, DNA of the trapped mf was extracted for miniPCR amplification of W. bancrofti and B. malayi DNA followed by DLFD. Thick blood smear staining for microfilariae detection was used as the gold standard technique. Microfilariae screening and visual species identification using our microfluidic device plus miniPCR-DLFD platform yielded results concordant with those of the gold standard thick blood smear technique. The microfluidic device, the miniPCR and the DLFD are all portable and do not require additional equipment. Use of this screening and visual species identification platform will facilitate reliable, cost-effective, and rapid surveillance for the presence of LF infection in resource-poor settings.

A miniPCR-Duplex Lateral Flow Dipstick Platform for Rapid and Visual Diagnosis of Lymphatic Filariae Infection.

Lymphatic filariasis (LF) is a neglected major tropical disease that is a leading cause of permanent and long-term disability worldwide. Significant progress made by the Global Programme to Eliminate Lymphatic Filariasis (GPELF) has led to a substantial decrease in the levels of infection. In this limitation, DNA detection of lymphatic filariae could be useful due to it capable of detecting low level of the parasites. In the present study, we developed a diagnostic assay that combines a miniPCR with a duplex lateral flow dipstick (DLFD). The PCR primers were designed based on the HhaI and SspI repetitive noncoding DNA sequences of Brugia malayi and Wuchereria bancrofti, respectively. The limits of detection and crossreactivity of the assay were evaluated. In addition, blood samples were provided by Thais living in a brugian filariasis endemic area. The miniPCR-DLFD assay exhibited a detection limit of 2 and 4 mf per milliliter (mL) of blood for B. malayi as well as W. bancrofti, respectively, and crossamplification was not observed with 11 other parasites. The result obtained from the present study was in accordance with the thick blood smear staining for the known cases. Thus, a miniPCR-DLFD is an alternative tool for the diagnosis of LF in point-of-collection settings with a modest cost (~USD 5) per sample.

Mitochondrial Genome of Brugia malayi Microfilariae Isolated From a Clinical Sample

Lymphatic filariasis is a neglected parasitic disease that is a leading cause of long-term disability. Information obtained from genome sequencing of filarial worm can help us identify systems in the worm that are likely to be useful for novel drug design. Brugia (B.) malayi is still the only lymphatic-dwelling filarial parasite with a nearly complete, fully annotated, and published genome. However, most previous studies were based on the FR3 strain of B. malayi, which originally was isolated from a human patient, and was adapted to the rodent model, then maintained in laboratories for more than 60 years. It is uncertain whether genetic variation exists, thus, sequencing of clinical isolates of lymphatic dwelling filarial parasites is a high priority. Here, we report for the first time the complete mitochondrial genome of B. malayi microfilariae from clinical isolate. Complete mitochondrial (mt) genome of the microfilariae isolated from a blood sample taken from a Thai subject living in Narathiwat Province, which is an endemic area of brugian filariasis, was assembled with sequencing reads obtained by Illumina sequencing. Gene annotation, phylogenetic analysis and single nucleotide polymorphism (SNP) were deployed. A complete 13,658-bp mt genome of B. malayi microfilaria was obtained, and it shows 68x coverage. Based on gene annotation, the mt genome consists of 12 protein-coding, two rRNA, and 23 tRNA genes. Phylogenetic analysis using all protein sequences of DNA sequences of mt genome or cytochrome c oxidase subunit I (COX1) revealed a close relationship among three lymphatic filariae (i.e., B. timori, zoonotic B. pahangi, and Wuchereria spp.). The SNPs in the COX1 gene can differentiate microfilariae of B. malayi in human from those found in canine. Furthermore, the number, order and transcription, and direction of B. malayi microfilariae mitochondrial genes were the same as those found in the FR3 strain of B. malayi. The comparison on mitochondrial genome of B. malayi could have important implications on the development of a new intervention or vaccine to treat or prevent this disease in endemic areas/regions around the world.

Identification and seasonal distribution of mosquito species in Telangana state, India

An entomological study was conducted to determine species composition, relative abundance, and seasonal population fluctuation of mosquitoes. Thirty localities were randomly selected and sampled once in summer, monsoon and winter seasons for a period of three years. Adult mosquitoes were collected from in and around human dwellings and animal sheds using aspirator and flash light between 6 PM and 7:30 PM hrs and 06:00 AM and 7:00 AM hrs. Larvae were collected from ditches, rock pool and other domestic habitats, reared to formation of adults in the lab. A total of 18425 mosquitoes were collected. Five genera (Culex, Anopheles, Aedes, Mansonia and Armigeres) were found to be circulating. Further, with respect to habitat, more number of mosquitoes were observed around cattle sheds and houses. Culex quinquefasciatus occupies top place, followed by Aedes albopictus and Culex gelidus, Culex tritaeniorhynchus with respect to density, whereas Mansonia uniformis occupies last place. Culex quinquifasciatus is top again followed by Culex gelidus and Aedes albopictus, Mansonia uniformis is last again with respect to distribution. The vector species studied were Aedes aegypti, Aedes albopictus for chikungunya and dengue, Anopheles stephensi, Anopheles culicifacies for malaria, Culex tritaeniorhynchus for Japanese encephalitis and Culex quiquefasciatus for lymphatic filaria.

Case Report: Periorbital Filariasis Caused by Brugia malayi

Brugia malayi is a lymphatic nematode that accounts for approximately 10% of lymphatic filariasis cases worldwide. It is endemic in several countries in South and Southeast Asia. In Thailand, B. malayi is endemic in the southern region. The extralymphatic presentation of B. malayi is rare. Here, we report the case of a woman residing in the central region of Thailand who presented with an erythematous periorbital nodule at the left medial canthal area caused by lymphatic filaria. A viable sexually mature filarial adult was removed from the lesion. The nematode species was identified as B. malayi by histology staining and DNA sequencing of the partial mitochondrial 12S ribosomal RNA (rRNA) gene. As far as we know, this is the first case report of B. malayi presenting with a periorbital nodule that has occurred in a disease non-endemic area of Thailand with possibly a zoonotic origin.

A lateral flow strip in combination with microfluidic device and polymerase chain amplification for rapid and visual detection of lymphatic filarial infection

Background: Lymphatic filariasis (LF) is a neglected tropical disease caused by the filarial nematode parasites which is transmitted by the bites of infective mosquitoes. The diagnosis of LF traditionally relies on the detection of circulating microfilariae (mf) using Giemsa-stained thick blood smears which has several limitations. Materials and methods: In the present study, we developed a lateral flow (LF) strip to be used in combination with a novel microfluidic device and polymerase chain reaction (PCR) for a rapid and visual detection of lymphatic filariae, Brugia malayi/ Wuchereria bancrofti infection in human blood samples. Results: The assay targets B. malayi HhaI gene and W. bancrofti Ssp gene. Prior to perform the assay, no DNA product clean up step required, thus, it can shorten time and reduce cost. The LF strip can detect as low as 10 pg of DNA product and no cross-reactivity with DNA of other parasites such as Gnathostoma spinigerum, cysticercisis soliumnor with DNA of other filariae i.e. Brugia pahangi, Dirofilaria immitis andD. repens. Conclusions: The developed LF strip shows high sensitivity and specificity, in combination with a novel microfluidic device and PCR, can be used as an alternative tool for the diagnosis of lymphatic filariasis.

Current Status of Parasite Infections in Indonesia: A Literature Review.

Indonesia and South Korea have become inseparable in various respects since the 2 countries established diplomatic relation in 1973. Indonesia is a tropical region that stretches across the equator, comprised of 5 main islands (Java, Kalimantan, Sumatra, Sulawesi, and Papua) and 4 archipelagoes (Riau, Bangka Belitung, Nusa Tenggara, and Maluku). As most population of Eastern Indonesia (Sulawesi, Papua and Nusa Tenggara & Maluku) live in poor areas, it is expected that there will be many parasites. Nevertheless, little is known about the status of parasites in Indonesia. This study examines the prevalences of malaria and lymphatic filaria, which are prevalent in Indonesia, as well as those of soil-transmitted-helminths (STH). As a result, the Plasmodium falciparum and P. vivax case loads are almost equal. The current prevalence of P. vivax is uniformly low (<5%) in all age groups and annual parasite incidence (API) showed decreasing tendency as 0.84 per 1,000 population in 2016. However, more than 65 million people still live in malaria epidemic regions. Lymphatic filariasis remains an important public health problem and 236 cities were classified as endemic areas in 514 cities/districts in 2017. It is difficult to ascertain the current prevalence rate of STH in Indonesia, although West Sumba and Southwest Sumba in East Nusa Tenggara reported prevalence rate of more than 20%. The study also considers the (sero) prevalences of other parasites identified in Indonesia. This report should be useful not only to parasitologists but also to travelers and people with business in Indonesia.

First study of topical selamectin efficacy for treating cats naturally infected with Brugia malayi and Brugia pahangi under field conditions.

Lymphatic filariae are important human and animal parasites. Infection by these parasites could lead to severe morbidity and has significant socioeconomic impacts. Topical selamectin is a semi-synthetic macrocyclic lactone that is widely used to prevent heartworm infection. Up until now, there were no studies that investigated the efficacy of selamectin in lymphatic filariae. Therefore, we aimed to study the chemotherapeutic and chemoprophylactic efficacies of selamectin use for cats in brugian filariasis-endemic areas in Southern Thailand. To assess chemotherapeutic efficacy of topical selamectin, eight Brugia malayi and six Brugia pahangi microfilaremic cats were treated with a single administration of topical selamectin. For chemoprophylactic efficacy assessment, a single application of topical selamectin was administrated to 9 healthy, uninfected cats. The cats in both groups were subjected to a monthly blood testing for microfilariae and filarial DNA for 1year. Topical selamectin treatment in B. malayi and B. pahangi microfilaremic cats showed 100% effectivity in eradicating microfilaremia but only 78.5% effectivity in eliminating filarial DNA. In the chemoprophylactic group, selamectin demonstrated 66.7% efficacy in preventing B. malayi infection. Our findings suggest that a single administration of 6mg/kg topical selamectin given every two months could effectively prevent B. malayi infection. Application of topical selamectin twice a year could block circulating microfilariae. Since there are no treatment guidelines currently available for lymphatic filarial infection in cats, the data obtained from this study could be used to guide the management of brugian lymphatic filarial infection in reservoir cats.

Therapeutic trial of doxycyclin plus ivermectin for the treatment of Brugia malayi naturally infected cats

Lymphatic filariasis (LF) is one of the neglected tropical diseases which causes permanent and long term disability worldwide. LF is caused by filarial nematode parasites, i.e. Wuchereria bancrofti, Brugia malayi, and B. timori. All available antifilarial drugs currently being used have shown a limited adulticidal activity. Discoveries of endosymbiont rickettsia-like bacterium, Wolbachia in filarial nematodes provided a novel approach for antibiotic use in eradication of filarial diseases. The earlier studies revealed the macrofilaricidal efficacy of doxycycline against filarial nematodes. Chemotherapeutic efficiency of doxycycline has been studied against many filarial parasites, but there are still no therapeutic trials of the drug regimens for B. malayi treatment in naturally infected cats. Thus, this study would be the first attempt to study the efficiency of doxycycline (DOXY) alone or in combination with ivermectin (IVM) for treatment of B. malayi in naturally infected cats. A total of 26 B. malayi-infected cats in the endemic areas were recruited and divided into 3 groups, receiving different treatment regimens; a single dose of ivermectin only (IVM), doxycycline only (DOXY) and a combination of ivermectin and doxycycline (DOXY-IVM). The efficacy of each therapatic regimen was evaluated by detecting the presence of microfilaria using parasitological and molecular techniques monthly up to 2 years after starting the treatment. The IVM treated group had a significant rapid reduction of microfilariae in the first month; however, recurrence of microfilaraemia was observed in some cats. By contrast, the DOXY and DOXY-IVM groups showed a better result with a gradual decrease in microfilariae with no recurrence. These 2 groups were not only virtually deprived of infection but also sustained the sterility of infection through the course of study. These results revealed the advantages of using in B. malayi treatment in cats. Doxycycline showed to have both microfilaricidal and adulticidal effects on lymphatic filariae which maintained the long-term response to control of B. malayi infection in cats.

Pyrosequencing Using SL and 5S rRNA as Molecular Markers for Identifying Zoonotic Filarial Nematodes in Blood Samples and Mosquitoes.

Lymphatic filariasis is principally caused by Wuchereria bancrofti, and Brugia malayi. The other two filarial nematode species, Brugia pahangi and Dirofilaria immitis, possibly cause human zoonotic diseases. We propose the development of a PCR assay linked with DNA pyrosequencing as a rapid tool to identify W. bancrofti, B. malayi, B. pahangi, and D. immitis in blood samples and mosquitoes. Primers targeting the fragment of the 5S ribosomal RNA and spliced leader sequences were newly designed and developed to identify these four filarial nematodes. Analytical sensitivity and specificity were evaluated. Pyrosequencing determination of nucleotide variations within 36 nucleotides for B. malayi and B. pahangi, and 32 nucleotides for W. bancrofti and D. immitis is sufficient for differentiation of those filarial nematodes, and for detection of intraspecies genetic variation of B. malayi. This analysis could detect a single B. malayi, B. pahangi, W. bancrofti, and D. immitis microfilaria in blood samples. Overall, the PCR-linked pyrosequencing-based method was faster than direct sequencing and less expensive than real-time PCR or direct sequencing. This is the possibility of choice that can be applied in a high-throughput platform for identification and surveillance of reservoirs and vectors infected with lymphatic filaria in endemic areas.

Cross reactive molecules of human lymphatic filaria Brugia malayi inhibit Leishmania donovani infection in hamsters

Coinfections are common in natural populations and the outcome of their interactions depends on the immune responses of the host elicited by the parasites. Earlier we showed that immunization with BmAFII (Sephadex G-200 eluted) fraction of human lymphatic filaria Brugia malayi inhibited progression of Leishmania donovani infection in golden hamsters. In the present study we identified cross reactive molecules of B. malayi, and investigated their effect on L. donovani infection and associated immune responses in the host. The sequence alignment and sharing of linear T- and B-cell epitopes in protein molecules of B. malayi and L. donovani counterparts were studied in silico. Hamsters were immunized with robustly cross reactive SDS-PAGE resolved fractions F6 (54.2–67.8kDa) and F9 (41.3–45.0kDa) of B. malayi and subsequently inoculated with amastigotes of L. donovani intracardially. F6 inhibited (∼72%) L. donovani infection and upregulated Th1 cytokine expression, lymphoproliferation, IgG2, IgG2/3 levels and NO production, and downregulated Th2 cytokine expression. Sequences in HSP60 and EF-2 of F6 and L. donovani counterparts were conserved and B- and T-cell epitopes in the proteins shared antigenic regions. In conclusion, leishmania-cross reactive molecules of filarial parasite considerably inhibited leishmanial infection via Th1-mediated immune responses and NO production. Common B- and T-cell epitope regions in HSP60 and EF-2 of the parasites might have contributed to the inhibitory effect on the L. donovani infection. Thus, leishmania-cross reactive filarial parasite molecules may help in designing prophylactic(s) against L. donovani.

Therapeutic efficacy and macrofilaricidal activity of doxycycline for the treatment of river blindness.

Onchocerca volvulus and lymphatic filariae, causing river blindness and elephantiasis, depend on endosymbiotic Wolbachia bacteria for growth, development, fertility, and survival. Clinical trials have shown that doxycycline treatment eliminates Wolbachia, causing long-term sterilization of adult female filariae and effecting potent macrofilaricidal activity. The continual reinfection by drug-naive worms that occurs in these trial settings dilutes observable anti-Wolbachia and antifilarial effects, making it difficult to estimate therapeutic efficacy and compare different doxycycline regimens, evaluated at different times after treatment. A meta-analytical modeling framework is developed to link all usable data collected from clinical trials measuring the Wolbachia status and viability of individual female adult worms collected at various times after treatment with 4, 5, or 6 weeks of daily 100 or 200 mg oral doxycycline. The framework is used to estimate efficacy parameters that are not directly measurable as trial outcomes. The estimated efficacy of doxycycline (the maximum proportional reduction in the percentage of adult female O. volvulus positive for Wolbachia) is 91%-94% on average, irrespective of the treatment regimen. Efficacy is >95% in the majority of trial participants. The life span of Wolbachia-depleted worms is reduced by 70%-80%, from approximately 10 years to 2-3 years. The efficacy parameters are pertinent to the prospects of using doxycycline on a "test and treat" basis for onchocerciasis control and confirm doxycycline as a potent macrofilaricidal therapy. The modeling approach is more generally relevant to the design and evaluation of clinical trials for antifilarial drugs conducted in endemic settings.

A Passion for Parasites

To know Dickson Despommier is to know his love of parasites. Despommier's academic text on parasitic diseases (co-edited by Robert Gwadz, Peter Hotez, and Charles Knirsch) is now in its 5th edition. In 2010, the long-time professor at Columbia University's Mailman School of Public Health tackled something new in “The Vertical Farm: Feeding the World in the 21st Century.” Now he's returned to his first love, and–like a chef creating a fine sauce–has reduced years of teaching and research into a toothsome tome for general readers. Okay, so it's not really a “tome.” “People, Parasites, and Plowshares—Learning from Our Body's Most Terrifying Invaders” is barely 200 pages, but those pages are indeed packed. Featured creatures include Trichinellae, hookworms, trypanosomes, schistosomes, lymphatic filariae, Toxoplasma, geohelminths, tapeworms, and Dracunculus. In his final chapter, Despommier serves up something different: poignant narratives depicting 1) a cluster of African men plagued with river blindness; and 2) a Chinese boy who develops sparganosis following treatment with a frog poultice. Both recreated scenarios are springboards for discussion around past, present, and future development of antiparasitic pharmaceuticals. Despommier's writing is conversational and fun. He quotes Mark Twain and shares “inside” stories (did you know, for example, that Yul Brynner once contracted trichinellosis at a restaurant in New York and later banked a hefty sum for his tsouris?). Despommier also pays homage to early giants of parasitology and the late Robert Desowitz, a superb spinner of parasite tales known to many ASTMH members. In some cases, the book segues from parasitology to global health. If only Guinea worm eradicators had installed hand-pumps next to step-wells (and thus provided truly safe drinking water), its author muses, think of the diarrheal deaths that might have been averted. And then there are the fascinating historical vignettes. In the opening chapter of “People, Parasites, and Plowshares,” Despommier chronicles the original sighting of Trichinella spiralis in human tissue. In 1835, James Paget was the curious medical student who first excised a tiny piece of “sandy diaphragm,” then–using a hand lens–spied coiled larvae in its muscle. Sadly, Paget did not receive much credit for the find. Why? Paget's professor (a man deliciously named “Wormald”) quickly rushed another snippet of diaphragm to Sir Richard Owen, who presented the discovery to the Royal Society. Nonetheless, the meat of “People, Parasites, and Plowshares” is modern parasite biology, whether Despommier is describing how Trichinellae nest in nurse cells—or hookworms penetrate intestinal mucosa and discharge anticoagulant–or African trypanosomes cycle their variant glycoproteins—or schistosomes acquire surface molecules that allow them to adhere to host tissue. Then, at the end of each chapter, the author returns to his “uber-message.” Probing the ways of parasites, he asserts, can yield major dividends in human health. That's the plowshare part. Why, for example, are fewer people afflicted with allergies and autoimmune conditions in places where geohelminths abound? And if schistosomes bearing beta 2 microglobulin can “don human clothing,” so to speak, how might their strategies aid efforts to transplant animal cells and organs into humans? These are just two of many questions raised in “People, Parasites, and Plowshares.” A sense of wonder also weaves through the work. “What happens next is pure poetry from the parasite's perspective,” Despommier says of a Toxoplasma tachyzoite entering its host cell. “T. gondii glides in … and is accepted as if it was some long lost relative who just showed up on the doorstep.” He then likens the messenger peptide IL12 to “the poison apple that puts the parasite to sleep.” Some lay readers will see ecology in a new way as Despommier describes how Toxoplasma oocysts from feral cats on California's eroded northern coastline have recently infected and killed sea otters. The principal casualties are otters who eat marine snails on a regular basis as opposed to now-imperiled abalone. Simply put, “People, Parasites, and Plowshares” is a rich, fulsome feast. It is also a gift to tropical medicine. If, as William Campbell writes in the book's Foreword, “… parasitologists sometimes worry that they are becoming an endangered species,” one thing is sure. This book should “chemo-attract” many new enthusiasts.

The Global Programme to Eliminate Lymphatic Filariasis: History and achievements with special reference to annual single-dose treatment with diethylcarbamazine in Samoa and Fiji.

Diethylcarbamazine (DEC), first introduced in 1947, was shown to have strong efficacy and safety for treatment of human lymphatic filariasis, which is caused mostly by a species Wuchereria bancrofti. Many studies to optimize the dosage and treatment schedule of DEC followed, and, based on the results, control programs with various regimens were implemented in different endemic areas/countries. By the mid 1970s, with endorsement by the WHO Expert Committee on Filariasis (3rd report, 1974), the standard DEC regimen for W. bancrofti infection in mass treatment had been established in principle: a total dose of 72 mg/kg of body weight given in 12 divided doses, once weekly or monthly, at 6 mg/kg each. Not long after the committee report, the efficacy of annual single-dose treatment at 6 mg/kg, which is only one twelfth of the WHO-recommended dose in a year, was reported effective in French Polynesia (study period: 1973-78), and later in Samoa (study period: 1979-81). These results were published between 1978 and 1985 in the Bulletin of WHO but received little attention. In the mid 1980s, the efficacy of ivermectin, the first-choice drug for onchocerciasis, against lymphatic filariae came to light. Since the effect at a single dose was remarkable, and often better than DEC, it was predicted that the newly introduced drug would replace DEC. Treatment experiments with ivermectin increased quickly in number. Meanwhile, annual single-dose mass drug administration (MDA) with DEC at 6 mg/kg was under scrutiny in Samoa and Fiji. In the early 1990s, the Samoan study, which covered the entire population of 160,000 with 3 annual MDAs, reported a significant reduction in microfilaria (mf) prevalence and mean mf density, while in Fiji, the efficacy of 5 rounds of annual MDA (total dose, 30 mg/kg) was shown to be as effective as 28 multi-dose MDA spread over 2 years (6 weekly plus 22 monthly treatments at 5 mg/kg; total dose, 140 mg/kg). Several additional studies carried out in Samoa in relation to the annual single-dose MDAs revealed that low density mf carriers, who have a very low mf count of 1-20/ml of venous blood, could not play a significant role in filariasis transmission.From around 1990, studies on spaced low-dose DEC treatments and various types of combination chemotherapy with DEC and ivermectin increased. Albendazole, a well-known anti-intestinal helminths agent, was later added to the combination. The main findings of these studies with W. bancrofti are: (i) a single dose of DEC at 6 mg/kg reduced mean mf density by ca. 90% 1 year after treatment; (ii) the same dose could damage/kill adult worms; (iii) a single dose of ivermectin at ca. 400 µg/kg was more effective than DEC in reducing mf density during the first year and was similarly or less effective in the second year; (iv) ivermectin probably could not kill adult worms; (v) a single combined dose of albendazole (400 mg) and DEC (6 mg/kg) was effective to reduce mf density by 85 to nearly 100% 12-24 months after treatment; and (vi) ivermectin or albendazole included in the combination chemotherapy produced “beyond-filariasis” benefits: clearance/reduction of intestinal helminths, and, additionally, in the case of ivermectin, skin-dwelling ectoparasites.The Global Programme to Eliminate Lymphatic Filariasis (GPELF) started its worldwide activities in 2000, with the target of elimination by 2020. The basic strategy is to conduct annual single-dose MDAs for 4-6 years. In 2000-2007, a minimum of 570 million individuals were treated in 48 of 83 endemic countries. The drugs used are DEC 6 mg/kg plus albendazole 400 mg in most countries, or ivermectin 200-400 µg/kg plus albendazole 400 mg particularly in onchocerciasis endemic countries in Africa. (MDAs with DEC alone had been used in India.)The GPELF achieved impressive results in terms of parasitological cure/improvement, clinical benefits, social and economic impacts, etc. However, the most impressive result of all was the programme’s success in mobilizing hundreds of millions of local people, who not only took drugs but many of them actively supported MDAs as drug distributors and volunteers. Beyond filariasis, the role people can play in supplementing rural health services is now a topic of discussion and a source of hope for a new sustainable system.

Parasite controls in Japan with emphasis on special characteristics

For a long period Japan was a country with a variety of parasites linked to the geo-climatic features of the country and agricultural modes. However national endeavors to promote parasite controls resulted in the successful elimination of those parasites by around 1970. In this short article, I briefly overview the control programs of soil-transmitted parasites, lymphatic filaria, Schistosoma japonicum and malaria, and cite some of the characteristic features and remarkable facts revealed in the course of individual control programs.

Multicentre evaluations of two new rapid IgG4 tests (WB rapid and panLF rapid) for detection of lymphatic filariasis

In the global effort to eliminate lymphatic filariasis (LF), rapid field-applicable tests are useful tools that will allow on-site testing to be performed in remote places and the results to be obtained rapidly. Exclusive reliance on the few existing tests may jeopardize the progress of the LF elimination program, thus the introduction of other rapid tests would be useful to address this issue. Two new rapid immunochromatographic IgG4 cassette tests have been produced, namely WB rapid and panLF rapid, for detection of bancroftian filariasis and all three species of lymphatic filaria respectively. WB rapid was developed using BmSXP recombinant antigen, while PanLF rapid was developed using BmR1 and BmSXP recombinant antigens. A total of 165 WB rapid and 276 panLF rapid tests respectively were evaluated at USM and the rest were couriered to another university in Malaysia (98 WB rapid, 129 panLF rapid) and to universities in Indonesia (56 WB rapid, 62 panLF rapid), Japan (152 of each test) and India (18 of each test) where each of the tests underwent independent evaluations in a blinded manner. The average sensitivities of WB rapid and panLF rapid were found to be 97.6% (94%–100%) and 96.5% (94%–100%) respectively; while their average specificities were both 99.6% (99%–100%). Thus this study demonstrated that both the IgG4 rapid tests were highly sensitive and specific, and would be useful additional tests to facilitate the global drive to eliminate this disease.

Pan LF-ELISA using BmR1 and BmSXP recombinant antigens for detection of lymphatic filariasis

BackgroundAnti-filarial IgG4 antibody has been shown to be a good marker for detection of lymphatic filaria infection. Previous studies demonstrated that anti-filarial IgG4 assay using BmR1 recombinant antigen was highly specific and sensitive for detection of brugian filariasis. For bancroftian filariasis, an equivalent assay employing recombinant antigen expressed from the ORF of SXP1 gene has been reported. In order to detect infections by all species of lymphatic filarial, BmR1 and BmSXP recombinant antigens were employed in the development of a pan LF-ELISA.MethodsBmR1 was previously produced while BmSXP recombinant antigen was produced by cloning the ORF of SXP1 gene from a Brugia malayi cDNA library, followed by expression in a bacterial expression system. Subsequently, each of the purified recombinant antigens (BmR1 and BmSXP) and mixture of different ratios of the two antigens (1:1, 2:1 and 1:2) were tested using IgG4-ELISA with various categories of infection and normal human serum samples.ResultsThe results showed that both recombinant antigens were highly specific (99%–100%). For detection of brugian filariasis, BmR1 antigen alone and the mixture of BmR1 with BmSXP (1:1) gave 98% sensitivity; while BmSXP antigen alone showed 84% sensitivity. For detection of bancroftian filariasis, BmSXP antigen was more sensitive (95%) than assays using either BmR1 or mixtures of the two recombinant antigens.ConclusionA sensitive and specific pan LF-ELISA for detection of lymphatic filariasis was successfully developed using two adjacent wells, each separately coated with BmR1 and BmSXP.