Profile of loiasis infection through clinical and laboratory diagnostics: the importance of biomarkers.

Background: Detection of Loa loa microfilariae in peripheral blood is insensitive given only 30% of individuals are microfilaraemic while 70% are amicrofilaraemic with a variety of clinical signs. Biomarkers may improve the diagnosis of loiasis.

Methods: A total of 545 individuals exposed to L.

The Human Filaria : Update on Diagnostics and Immune Response.

loiasis was considered an anecdotal disease 30 years ago. Its spread in Equatorial Africa and the side effects associated with mass drug administration programs against filariasis in co-endemic areas have drawn the attention of the international research community. Progress in research conducted to date has provided insight into the immunobiology of this parasite.

infection detection using biomarkers: current perspectives.

is originally a restricted filarial worm from central Africa and some west African countries. However, numerous imported cases are being reported throughout the world due to human movement. Traditionally, its diagnosis is based on identification of microfilariae in the peripheral blood or the passage of the adult worm under the conjunctiva.

Serological Evidence for the Circulation of Rift Valley Fever Virus in Domestic Small Ruminants in Southern Gabon.

Rift Valley fever (RVF) is a zoonotic disease, which caused several epidemics in humans in many countries of Africa. Using an inhibition enzyme-linked immunosorbent assay (ELISA), real-time reverse transcription PCR, and nested one-step reverse transcription PCR, we conducted a cross-sectional study in populations of sheep and goats from the Mongo County in 2014 to determine the circulation of the Rift Valley fever virus (RVFV) in small ruminants from this area. From a total of 201 small ruminants (95 sheep and 106 goats), the overall IgG seroprevalence against the RVFV was 6.

In vitro proliferation and production of cytokine and IgG by human PBMCs stimulated with polysaccharide extract from plants endemic to Gabon.

Polysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC) (5×10⁵ cells/mL) proliferation, cytokine and immunoglobulin G (IgG) assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS) and concanavalin A (ConA) from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA).

Development of a highly sensitive loop-mediated isothermal amplification (LAMP) method for the detection of Loa loa.

The filarial parasite Loa loa, the causative agent of loiasis, is endemic in Central and Western Africa infecting 3-13 million people. L. loa has been associated with fatal encephalopathic reactions in high Loa-infected individuals receiving ivermectin during mass drug administration programs for the control of onchocerciasis and lymphatic filariasis.

Epidemiology of concomitant infection due to Loa loa and Mansonella perstans in Gabon.

Background: The filarial parasites Loa loa and Mansonnella perstans are endemic in the central and western African forest block. Loa loa is pathogenic and represents a major obstacle to the control of co-endemic filariae because its treatment can cause fatal complications such as encephalitis.

Methodology/principal Findings: 4392 individuals aged over 15 years were studied both by direct examination and a concentration technique.

Risk factors for Zaire ebolavirus--specific IgG in rural Gabonese populations.

Background: In Gabon, several Ebolavirus outbreaks have occurred exclusively in the northeastern region. We conducted a large serosurvey to identify areas and populations at risk and potential demographic, clinical, and behavioral risk factors.

Methods: Blood samples and clinical and sociodemographic data were collected from 4349 adults and 362 children in a random sample of 220 villages in the 9 provinces of Gabon.

Prevalence of Plasmodium falciparum infection in asymptomatic rural Gabonese populations.

Background: Malaria may be perennial or epidemic in sub-Saharan Africa, and its transmission may be stable or unstable, depending on the region. The prevalence of asymptomatic Plasmodium falciparum carriage is poorly documented in Gabon. A large survey of P.

In vitro activities of plant extracts on human Loa loa isolates and cytotoxicity for eukaryotic cells.

Loa loa, a filarial worm, can cause fatal encephalitis in humans. In an attempt to find alternatives to the standard treatments (ivermectin and diethylcarbamazine citrate), we tested 12 methanolic extracts of nine traditional plant remedies. The extracts (100-0.

Production and immunological characterization of a recombinant subunit of a Loa loa polyprotein antigen.

Diagnosis of loiasis and analysis of the specific immune response are limited by a paucity of parasite material. To circumvent this problem, a Loa loa antigen has been expressed in a prokaryote vector (pTrcHis). Immunization of Balb/c mice with this soluble recombinant protein produced a strong antibody response, with antibodies recognizing 2 major bands of 38 and 20 kDa in a native crude extract of Loa loa adult worms and microfilariae on Western blots.

[Serological study on toxoplasmosis among pregnant women from Franceville, Gabon].

The serological prevalence of Toxoplasma gondii was studied among 839 pregnant women in two hospitals from Franceville (Gabon), between May 2007 and December 2007. Specific T gondii IgG and IgM were measured by Enzyme Linked Fluorescent Assay (ELFA). Datation of the infection was carried out by avidity test.

Ethics committees in western and central Africa: concrete foundations.

The involvement of developing countries in international clinical trials is necessary for the development of appropriate medicines for local populations. However, the absence of appropriate structures for ethical review represents a barrier for certain countries. Currently there is very little information available on existing structures dedicated to ethics in western and central Africa.

Parasitological and immunological effects induced by immunization of Mandrillus sphinx against the human filarial Loa loa using infective stage larvae irradiated at 40 Krad.

Six mandrills were immunized with 150 Loa loa infective stage larvae (L3) irradiated with 40 Krad, and challenged with 100 L3, 60 days after initial vaccination. The parasitological outcome of this immunization was compared to results from six mandrills infected with normal L3. No clear association was seen between vaccination and microfilaremia until day 245 when a significant drop in the level of microfilaria occurred in vaccinated compared to infected animals (5 vs 10 mf/ml; p = 0.

Evidence against Wolbachia symbiosis in Loa loa.

BACKGROUND: The majority of filarial nematode species are host to Wolbachia bacterial endosymbionts, although a few including Acanthocheilonema viteae, Onchocerca flexuosa and Setaria equina have been shown to be free of infection. Comparisons of species with and without symbionts can provide important information on the role of Wolbachia symbiosis in the biology of the nematode hosts and the contribution of the bacteria to the development of disease. Previous studies by electron microscopy and PCR have failed to detect intracellular bacterial infection in Loa loa.

Expression of filarial-specific IgG subclasses under different transmission intensities in a region endemic for loiasis.

Specific IgG subclasses were investigated in two villages (Okoumbi and Ndjokaye) in southeast Gabon with different Loa loa transmission intensities of approximately 9,000 and 1,300 infective larvae (L3) per person per year, respectively. IgG subclasses were measured by an enzyme-linked immunosorbent assay (ELISA) using extracts of L. loa L3, microfilariae (MF), or adult worms.

Transmission intensity affects both antigen-specific and nonspecific T-cell proliferative responses in Loa loa infection.

T-cell proliferative responses were studied in two villages in Gabon with different levels of Loa loa transmission. The first village (Okoumbi) had an annual transmission potential (ATP) of approximately 9,000 infective larvae (L3)/person/year (high transmission village), while the second village (Ndjokaye) had an ATP of approximately 1,000 L3/person/year (low transmission village). Proliferation and cytokine assays were performed on peripheral blood mononuclear cells (PBMC) from individuals aged 18 years and over using either mitogens (concanavalin A or phytohemagglutinin), antigens (purified protein derivative [PPD], irrelevant antigen), or soluble extracts of L3, microfilariae, or adult L.

The relationship between parasitological status and humoral responses to Loa loa antigens in the Mandrillus sphinx model after immunization with irradiated L3 and infection with normal L3.

In order to identify antigens associated with protection and those associated with active infection, the humoral immune response of 6 Mandrillus sphinx immunized with 150 irradiated L3 and challenged with 100 normal L3 of Loa loa or 6 animals infected with 100 L3 were compared. The plasma of these animals was analysed by Western blot using adult, Mf and L3 antigens. Several antigens with molecular weights varying from 120 kDa to 13 kDa were recognized by the plasma of all animals.

IgG subclass recognition of Loa loa antigens and their correlation with clinical status in individuals from Gabon.

In endemic areas for Loa loa, a significant percentage of actively infected individuals have no circulating microfilariae, an observation which implies the existence of a stage-specific immune response. In an attempt to define the immunological basis of the amicrofilaraemic state, the reactivity of antigens from adult, microfilariae and infective larvae of L. loa was examined by Western blotting with individual serum samples from four clinically defined groups (high microfilaraemic, low microfilaraemic, amicrofilaraemic and endemic controls) using IgG subclass-specific reagents and IgE.

High levels of parasite-specific IgG1 correlate with the amicrofilaremic state in Loa loa infection.

To investigate the mechanisms of protective immunity operating in Loa loa infection, 56 persons from a L. ioa-endemic village in southeast Gabon were examined over a 7-year period. The level of L.

Markers of Loa loa infection in permanent residents of a loiasis endemic area of Gabon.

Different markers of infection were analyzed in 56 permanent residents of a Loa loa endemic village in Gabon. The population was divided into those with parasitological evidence of L. loa infection and those with no history of loiasis over the period of observation (c.

Loa loa: structural diversity of a 15-kDa repetitive antigen.

A ladder antigen of Loa loa was identified on Western blots of all life cycle stages probed with loaisis sera. The smallest subunit has a relative M(r) of about 15 kDa and larger subunits represent size increments of 15.0 kDa.