Fan PC et al. (1985) Southeast Asian J Trop Med Public Health "Experimental infection of subperiodic Brugia malayi in laboratory rats with emphasis on evaluation by four techniques."

Hsu YP, Huang CM, Wu CC, Ho CM, Fan PC

[Southeast Asian J Trop Med Public Health, 1985]

Infective larvae of subperiodic B. malayi from South Kalimantan (Borneo), Indonesia collected from laboratory-raised Ae. togoi mosquitoes after feeding on infected mongolian gerbils (Meriones unguiculatus) were inoculated subcutaneously into the groin areas of 15 SD and 36 LE rats. Blood was examined weekly by membrane filtration and thick smears starting 10 weeks post-infection. Microfilariae were found in 3 SD and 4 LE rats, the mf infection rate of 20% and 11% respectively. The prepatent period was significantly shorter in the SD rats (99-112 days) than those in the LE rats (110-153 days). The patent period was longer in the LE rats (208-703 days) than in the SD rats (236-543 days), and the mf density was similar (17.5 mf/20 c.mm blood against 16 mf/20 c.mm blood). At necropsy, 6 (3 female and 3 male) adult worms were recovered from 3 of 6 SD rats and 12 (9 female and 3 male) adult worms from 4 of 20 LE rats; all worms were found in the testes. The results of xenodiagnostic, histochemical staining and measuring spicules and protuberances, demonstrated clearly the difference between both species of Brugia. All dissected Ar. subalbatus mosquitoes exposed to B. pahangi became infected (100%), but none of those to subperiodic B. malayi were infected (0%). The mf of both species of Brugia in thick films stained with naphthol-AS-TR-phosphate showed that the excretory and anal pores of subperiodic B. malayi mf exhibited acid phosphatase activity and only a little activity was seen in other parts; while B. pahangi mf showed heavy diffuse acid phosphatase activity along the entire length of the body.(ABSTRACT TRUNCATED AT 250 WORDS)

Hamley JID et al. (2020) J Infect Dis "Structural Uncertainty in Onchocerciasis Transmission Models Influences the Estimation of Elimination Thresholds and Selection of Age Groups for Seromonitoring."

Coffeng LE, Milton P, de Vlas SJ, Stolk WA, Basanez MG, Walker M, Hamley JID

[J Infect Dis, 2020]

BACKGROUND: The World Health Organization recommends monitoring Onchocerca volvulus Ov16 serology in children aged <10 years for stopping mass ivermectin administration. Transmission models can help to identify the most informative age groups for serological monitoring and investigate the discriminatory power of serology-based elimination thresholds. Model predictions depend on assumed age-exposure patterns and transmission efficiency at low infection levels. METHODS: The individual-based transmission model, EPIONCHO-IBM, was used to assess (1) the most informative age groups for serological monitoring using receiver operating characteristic curves for different elimination thresholds under various age-dependent exposure assumptions, including those of ONCHOSIM (another widely used model), and (2) the influence of within-human density-dependent parasite establishment (included in EPIONCHO-IBM but not ONCHOSIM) on positive predictive values for different serological thresholds. RESULTS: When assuming EPIONCHO-IBM exposure patterns, children aged <10 years are the most informative for seromonitoring; when assuming ONCHOSIM exposure patterns, 5-14 year olds are the most informative (as published elsewhere). Omitting density-dependent parasite establishment results in more lenient seroprevalence thresholds, even for higher baseline infection prevalence and shorter treatment durations. CONCLUSIONS: Selecting appropriate seromonitoring age groups depends critically on age-dependent exposure patterns. The role of density dependence on elimination thresholds largely explains differing EPIONCHO-IBM and ONCHOSIM elimination predictions.

Lont YL et al. (2017) PLoS Negl Trop Dis "Modelling Anti-Ov16 IgG4 Antibody Prevalence as an Indicator for Evaluation and Decision Making in Onchocerciasis Elimination Programmes."

Domingo GJ, Golden A, Coffeng LE, de Los Santos T, Lont YL, de Vlas SJ, Stolk WA

[PLoS Negl Trop Dis, 2017]

BACKGROUND: Onchocerciasis is targeted for elimination in Africa through annual or biannual ivermectin mass drug administration (MDA). An immunodiagnostic test, based on the detection of human IgG4 antibodies in the blood to the Onchocerca volvulus-specific antigen Ov16, is one of the recommended tools for determining whether transmission is interrupted and mass treatment can stop. For different transmission settings, the relationship between post-MDA Ov16 antibody prevalence in children (measured 1 year after the last round of MDA) and the duration and coverage of MDA, the mf prevalence in the population, and the probability that onchocerciasis is eventually eliminated is explored through mathematical modelling. METHODOLOGY: The ONCHOSIM model was extended with new output on the Ov16 antibody serostatus of individuals. Seroconversion was assumed to be triggered by the first worm establishing in the host, with seroconversion occurring either before maturation, after maturation or only after the start of mf production. We are mainly interested in seroconversion rates in children, and for now ignore the possibility of seroreversion to simplify the model. PRINCIPAL FINDINGS: Yearly repeated MDA leads to a strong reduction in the in the parasite acquisition rate in humans. This reduces the seroconversion rate in newborns and young children, while those who seroconverted before the start of control remain antibody positive. Both the microfiladermia prevalence in the population aged 5 years and above and the Ov16 antibody prevalence in children under 10 declined with increasing duration of MDA. The association between either of these indicators and the model-predicted probability of elimination was not influenced much by the assumed treatment coverage levels, but was found to depend on baseline endemicity levels, assumptions regarding the trigger of seroconversion, and diagnostic test characteristics (sensitivity and specificity). CONCLUSIONS: Better understanding of the dynamics of Ov16 antibody responses is required for accurate interpretation of seroprevalence data and more precise estimation of endpoint for MDA. Our study demonstrates that this endpoint will be dependent on baseline endemicity levels, which should be taken into account in guidelines for defining when to stop MDA.

Vinkeles Melchers NVS et al. (2019) Clin Infect Dis "Projected number of people with onchocerciasis-loiasis co-infection in Africa, 1995 to 2025."

Vinkeles Melchers NVS, Coffeng LE, Tekle AH, Boussinesq M, Stolk WA, Remme JH, Pion SDS, Wanji S, Zoure HGM, Pedrique B

[Clin Infect Dis, 2019]

BACKGROUND: Onchocerciasis elimination through mass drug administration (MDA) is hampered by co-endemicity of Loa loa in Africa, as people with high L. loa microfilariae (mf) density can develop serious adverse events (SAEs) after ivermectin treatment. We assessed the geographical overlap of onchocerciasis and loiasis prevalence and estimated the number of co-infected individuals at risk of post-ivermectin SAEs in West and Central Africa from 1995 to 2025. METHODS: Focussing on regions with suspected loiasis transmission in 14 African countries, we overlaid pre-control maps of loiasis and onchocerciasis prevalence to calculate pre-control prevalence of co-infection by 5x5 km pixel, distinguishing different categories of L. loa mf intensity. Using statistical and mathematical models, we predicted the prevalence of both infections and co-infection for 2015 and 2025, accounting for the impact of MDA with ivermectin. RESULTS: The number of people infected with onchocerciasis was predicted to decline from almost 19 million in 1995 to 4 million in 2025. Of these, 137,000 people were estimated to also have L. loa hypermicrofilaraemia (20,000 L. loa mf/mL) in 1995, declining to 31,000 in 2025. In 2025, 92.8% of co-infected cases with loiasis hypermicrofilaraemia are predicted to live in hypoendemic areas currently not targeted for MDA. CONCLUSIONS: Loiasis co-infection is a major concern for onchocerciasis elimination in Africa. We predict that under current strategies, at least 31,000 co-infected people will still require treatment for onchocerciasis in 2025 while being at risk of SAEs, justifying continued efforts in research and development for safer drugs and control strategies.

Nolan RA (1972) Mycologia "Asteromyces cruciatus from North America."

Nolan RA

[Mycologia, 1972]

The hyphomycete Asteromyces cruciatus F. & Mme Moreau was described without a Latin diagnosis or a designated type. The taxon was validated by Hennebert. The known distribution of this monotypic genus has been limited. F. and Mme Moreau found the fungus in sand dunes at Point du Siege (under Psamma sp.) and between Franceville and Le Home (under Agropyrum sp.) on the Normandy coast of France. Brown found A. cruciatus in open sand in the intertidal zone at Studland, Dorset and Sandwich, Kent, England; and Nicot found it in sand dunes and beach samples at Malo-les-Bains on the North Sea coast of France.

Dougherty EC (1953) J Parasitol "The axenic cultivation of Rhabditis briggsae Dougherty and Nigon, 1949 (Nematoda: Rhabditidae). III. Liver preparations with various supplementation."

Dougherty EC

[J Parasitol, 1953]

The axenic cultivation (i.e., growth in the absence of other living organisms) of the free-living soil nematode, Rhabditis briggsae, requires a complex medium including one or more heat-labile, protein-like substances which have been termed "factor Rb". It has been shown that factor Rb can be provided by preparations from liver or chick embryo juice or by human plasma or certain of its fractions. Moreover, it has recently been reported in abstract that a dialysed fraction of buffered aqueous liver extract will support excellent growth of R. briggsae when supplemented with known substances only. The present paper reports the results of recent studies on the nature and properties of factor Rb in liver protein and on various supplementations of certain unheated liver preparations as media for R. briggsae. Aqueous, unheated horse liver extract (hereinafter referred to as LE), prepared by centrifuging liver homogenate and taking supernatant, has been treated in various ways to provide information on the properties of factor Rb. Such preparations have been variously supplemented and tested as media for the axenic cultivation of R. briggsae. The principle supplementation used has been the supernatant (ALE) from autoclaved LE. Both partly and completely defined supplementations have also been employed. From these studies some advance has been made in the direction of a completely defined medium for R.

Franz CJ et al. (2012) J Virol "Complete genome sequence of Le Blanc virus, a third Caenorhabditis nematode-infecting virus."

Felix MA, Zhao G, Franz CJ, Wang D

[J Virol, 2012]

Orsay virus and Santeuil virus, the first known viruses capable of naturally infecting the nematodes Caenorhabditis elegans and Caenorhabditis briggsae, respectively, were recently identified by high-throughput sequencing of wild Caenorhabditis strains. By similar analysis of another wild C. briggsae isolate, we have now discovered and sequenced the complete genome of a third novel virus, Le Blanc virus, that is distantly related to Orsay and Santeuil viruses. All three viruses are positive-sense RNA viruses with bipartite genomes that are most closely related to nodaviruses. Identification of a third virus capable of infecting Caenorhabditis nematodes enables comparative analysis of this clade of viruses and strengthens this model for investigating virus-host interactions.

Eberhardt AG et al. (2008) Vet Parasitol "The Strongyloides (Nematoda) of sheep and the predominant Strongyloides of cattle form at least two different, genetically isolated populations."

Mayer WE, Eberhardt AG, Streit A, Bonfoh B

[Vet Parasitol, 2008]

Strongyloides sp. (Nematoda) are very wide spread small intestinal parasites of vertebrates that can form a facultative free-living generation. Most authors considered all Strongyloides of farm ruminants to belong to the same species, namely Strongyloides papillosus (Wedl, 1856). Here we show that, at least in southern Germany, the predominant Strongyloides found in cattle and the Strongyloides found in sheep belong to separate, genetically isolated populations. While we did find mixed infections in cattle, one form clearly dominated. This variety, in turn, was never found in sheep, indicating that the two forms have different host preferences. We also present molecular tools for distinguishing the two varieties, and an analysis of their phylogenetic relationship with the human parasite Strongyloides stercoralis and the major laboratory model species Strongyloides ratti. Based on our findings we propose that Strongyloides from sheep and the predominant Strongyloides from cattle should be considered separate species as it had already been proposed by [Brumpt, E., 1921. Recherches sur le determinisme des sexes et de l''evolution des Anguillules parasites (Strongyloides). Comptes rendu hebdomadaires des seances et memoires de la Societe de Biologie et de ses filiales 85, 149-152], but was largely ignored by later authors. For nomenclature, we follow [Brumpt, E., 1921. Recherches sur le determinisme des sexes et de l''evolution des Anguillules parasites (Strongyloides). Comptes rendu hebdomadaires des seances et memoires de la Societe de Biologie et de ses filiales 85, 149-152] and use the name S. papillosus for the Strongyloides of sheep and the name Strongyloides vituli for the predominant Strongyloides of cattle.

Frezal L et al. (2019) J Virol "Noda-like RNA viruses infecting Caenorhabditis nematodes: sympatry, diversity and reassortment."

Felix MA, Jung H, Frezal L, Tahan S, Wang D

[J Virol, 2019]

Three RNA viruses related to nodaviruses were previously described to naturally infect the nematode <i>Caenorhabditis elegans</i> and its relative <i>Caenorhabditis briggsae.</i> Here we report on a collection of over 50 viral variants from wild-caught <i>Caenorhabditis.</i> We describe the discovery of a new related virus, the Mlnik virus, infecting <i>C. briggsae</i>, which similarly infects intestinal cells. In France, a frequent pattern of co-infection of <i>C. briggsae</i> by the Santeuil virus and Le Blanc virus was observed at the level of an individual nematode and even a single cell. We do not find evidence of reassortment between the RNA1 and RNA2 molecules of Santeuil and Le Blanc viruses. However, by studying patterns of evolution of each virus, reassortments of RNA1 and RNA2 among variants of each virus were identified. We develop assays to test the relative infectivity and competitive ability of the viral variants and detect an interaction between host genotype and Santeuil virus genotype, such that the result depends on the host strain.<b>IMPORTANCE</b> The roundworm <i>Caenorhabditis elegans</i> is a laboratory model organism in biology. We study natural populations of this small animal and its relative <i>C. briggsae</i> and the viruses that infect them. We previously discovered three RNA viruses related to nodaviruses and here describe a fourth one, called the Mlnik virus. These viruses have a genome composed of two RNA molecules. We find that two viruses may infect the same animal and the same cell. The two RNA molecules may be exchanged between variants of a given viral species. We study the diversity of each viral species and devise an assay of their infectivity and competitive ability. Using this assay, we show that the outcome of the competition also depends on the host.

Franz CJ et al. (2014) Virology "Orsay, Santeuil and Le Blanc viruses primarily infect intestinal cells in Caenorhabditis nematodes."

Felix MA, Frezal L, Renshaw H, Wang D, Jiang Y, Franz CJ

[Virology, 2014]

The discoveries of Orsay, Santeuil and Le Blanc viruses, three viruses infecting either Caenorhabditis elegans or its relative Caenorhabditis briggsae, enable the study of virus-host interactions using natural pathogens of these two well-established model organisms. We characterized the tissue tropism of infection in Caenorhabditis nematodes by these viruses. Using immunofluorescence assays targeting proteins from each of the viruses, and in situ hybridization, we demonstrate viral proteins and RNAs localize to intestinal cells in larval stage Caenorhabditis nematodes. Viral proteins were detected in one to six of the 20 intestinal cells present in Caenorhabditis nematodes. In Orsay virus-infected C. elegans, viral proteins were detected as early as 6h post-infection. The RNA-dependent RNA polymerase and capsid proteins of Orsay virus exhibited different subcellular localization patterns. Collectively, these observations provide the first experimental insights into viral protein expression in any nematode host, and broaden our understanding of viral infection in Caenorhabditis nematodes.