Humane Infektion mitGongylonema pulchrum

HISTORY

A 27-year-old woman repeatedly attended an outpatient clinic and reported sensations of movement within the buccal mucosa. Various local inspections were without any obvious abnormal findings. A few days later the patient brought a filiform structure, which she had extracted from the affected mucosa by manipulation with her toothbrush.

INVESTIGATION

Microscopy indicated a gravid female nematode of the genus Gonglyonema.

DIAGNOSIS

Gonglyonem pulchrum infection.

TREATMENT AND COURSE

Careful inspection revealed a second worm at the other side of the oral cavity, which was extracted by local incision. After removal of the second worm the patient remained free of symptoms without any further therapy.

CONCLUSION

Even obviously very unusual symptoms, which might be indicative of a dermatozoic delusion, should be carefully clarified. In some cases it may be appropriate to consult a specialized institutions or laboratory to rule out a possible parasitic infections.

The relationships between the burden of adult parasites, host age and the microfilarial density in human onchocerciasis

We investigate the relationship between the microfilarial density in the skin and the burden of adult female Onchocerca volvulus by analysing pre-control nodulectomy data which allow for a direct approach, independent of exposure. The data of 169 patients in Burkina Faso and 182 patients in Liberia represent savannah and forest onchocerciasis in West Africa, respectively. Whereas in Burkina Faso, a saturating relationship between microfilarial density and worm burden suggests the operation of density-dependent processes within human hosts, the Liberian data show a linear relationship implying no density dependence. The differences may derive from differences between both parasite strains, i.e. the savannah or the forest strain of O. volvulus. Consistently for both parasite strains and independent of the worm burden, the microfilarial density increases with host age emphasising the concept of the acquisition of immunological tolerance. In male hosts in Liberia, the microfilarial density increases stronger with the worm burden than in female hosts, whereas such sex-specific differences cannot be found in Burkina Faso. In the methodological part of this investigation, we suggest the beta-distribution to be most appropriate for describing variability in microfilarial densities and we present an approach to consider the uncertainty in the adult parasite burden which cannot be determined precisely in helminth infections. Implications of density dependence are discussed with respect to immunological processes in the human host and with respect to the success of control programs. The relationships described show that regulatory processes between the parasite and the human host are multi-dimensional, operating within a high degree of biological variability.

Density-dependent parasite establishment suggests infection-associated immunosuppression as an important mechanism for parasite density regulation in onchocerciasis

The modulation of human immune response by filarial parasites has yielded contradictory experimental findings and attracted much controversy. We address the unresolved question of acquisition, establishment and accumulation of Onchocerca volvulus by using a modelling approach that relates computer simulations to cross-sectional data concerning parasite burdens in 913 West African onchocerciasis patients. It is shown that the acquisition of O. volvulus is not constant with host age; instead, the analysis of age profiles of parasite burdens strongly indicate the operation of immunosuppressive processes within the human host, associated with the presence of adult parasites or microfilariae. It is suggested that these processes suppress immunity against incoming infective larvae (L3), which themselves act as an immune modulating component once they have successfully overcome the barrier of concomitant immunity. Suppression of parasite-specific immunity leads to parasite establishment rates which increase along with the parasite burden, but which hardly depend on hyperendemic annual transmission potentials. Children, still immunocompetent due to low parasite burdens, acquire 0.1-0.5 adult female parasites per year, whereas older people, immunosuppressed due to high burdens, acquire 2-4 adult female parasites per year. Differences in parasite establishment between the forest and the savannah strains of O. volvulus are quantified and dynamic aspects of density-dependent parasite establishment discussed.

An internal control for the detection of Onchocerca volvulus DNA by PCR-ELISA and rapid detection of specific PCR products by DNA Detection Test Strips

We developed a polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA) for the detection of Onchocerca volvulus DNA. To standardize the PCR and to avoid false-negative results, an internal control DNA was co-amplified by the same set of primers. We differentiated the wild-type PCR product of the O-150 DNA sequence from the internal control by specific DNA probes. Detection of biotinylated PCR products by DNA probes was performed by ELISA to quantify the PCR product or by DNA Detection Test Strips as a rapid field technique. The methods were evaluated on skin biopsies from individuals living in an area endemic for O. volvulus in Uganda, but with low microfilaria densities because of ivermectin treatment. Microfilaria density was assessed by a single skin snip and a second skin snip was examined by PCR. Among 69 samples from microfilaria carriers, 47 (68%) were positive by ELISA and 55 (80%) by test strip detection of PCR products. When 39 samples of microfilaria-negative individuals from the same area were tested, 10 (27%) were positive by ELISA and 12 (31%) by test strips. None of the 19 samples obtained from persons living in an area not endemic for O. volvulus but endemic for Mansonella streptocerca was positive in either test. Although the ELISA is theoretically more sensitive than the test strips for the detection of PCR products, examination of field samples revealed that the test strip method had a higher operational sensitivity and was more convenient to perform. Thus, the DNA Detection Test Strips are a rapid and low-tech tool for identification of PCR products in laboratories of countries endemic for onchocerciasis.

Depletion of wolbachia endobacteria in Onchocerca volvulus by doxycycline and microfilaridermia after ivermectin treatment

Ivermectin is the drug used for mass chemotherapy of onchocerciasis within the WHO African Programme for Onchocerciasis Control. This approach aims to eliminate the disease as a public health problem but using one dose per year may not completely interrupt transmission since it does not suppress microfilaridermia thoroughly enough. Here we show that additional treatment with doxycycline, previously shown to sterilise adult female worms for a few months by depletion of symbiotic wolbachia endobacteria, significantly enhances ivermectin-induced suppression of microfilaridermia, rendering anti-wolbachia treatment a promising basis for blocking transmission by a drug-based approach.

Neutrophil accumulation around Onchocerca worms and chemotaxis of neutrophils are dependent on Wolbachia endobacteria

Unlike in many other helminth infections, neutrophilic granulocytes are major cellular components in the hosts immune response against filarial worms. The pathways that drive the immune response involving neutrophils are unclear. This study shows that Wolbachia endobacteria (detectable by polyclonal antibodies against endobacterial heat shock protein 60 and catalase and by polymerase chain reaction being sensitive to doxycycline treatment) are direct and indirect sources of signals accounting for neutrophil accumulation around adult Onchocerca volvulus filariae. Worm nodules from untreated onchocerciasis patients displayed a strong neutrophil infiltrate adjacent to the live adult worms. In contrast, in patients treated with doxycycline to eliminate the endobacteria from O. volvulus and to render the worms sterile, the neutrophil accumulation around live adult filariae was drastically reduced. Neutrophils were absent in worm nodules from the deer filaria Onchocerca flexuosa, a species which does not contain endobacteria. Extracts of O. volvulus extirpated from untreated patients showed neutrophil chemotactic activity and in addition, induced strong TNF-alpha and IL-8 production in human monocytes, in contrast to filarial extracts obtained after doxycycline treatment. Thus, neutrophil chemotaxis and activation are induced directly by endobacterial products and also indirectly via chemokine induction by monocytes. These results show that the neutrophil response is a characteristic of endobacteria-containing filariae.

Eosinophil granule proteins in serum and urine of patients with helminth infections and atopic dermatitis

Eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EPX) are cytotoxic molecules involved in helminth infections and allergic reactions. Hitherto most clinical chemical studies have been concerned with the analysis of serum ECP in allergic diseases. The aim of this study was to examine whether serum as well as urine levels of these proteins are useful clinical chemical parameters in helminthiases and allergic diseases such as atopic dermatitis. Comparing these diseases under the same methodological conditions, levels of ECP and EPX were generally higher in helminthiases than in atopic dermatitis and non-helminth, non-allergic diseases. The highest levels of both proteins occurred in tropical worm diseases, in particular hookworm disease and onchocerciasis. When comparing helminthiases with allergic disorder, only hookworm disease (ECP and EPX) and onchocerciasis (EPX) exhibited significantly higher eosinophil cationic protein serum levels than atopic dermatitis. In patients with schistosomiasis mansoni and egg loads of > 1000-10 000 eggs/g stool (epg) EPX serum levels were significantly higher than in patients exhibiting loads < 1000 epg. Urinary analyses revealed only EPX to be present in measurable amounts. Levels of this protein were much higher in urine of patients with hookworm disease and onchocerciasis than in those with atopic dermatitis and in healthy controls. The results suggest that besides serum EPX, urinary EPX may be a useful clinical chemical parameter in eosinophilia of helminth and allergic aetiology.

Use of the recombinant Onchocerca volvulus protein Ov20/OvS1 for the immunodiagnostic differentiation between onchocerciasis and mansonelliasis and for the characterization of hyperreactive onchocerciasis (sowda)

The protein Ov20/OvS1 was used as antigen in ELISA and Western blot in order to differentiate onchocerciasis from African mansonelliasis and to characterize the hyperreactive form of Onchocerca volvulus infection (sowda). The specificity of the IgG4 Western blot was 98% for the differentiation between persons with onchocerciasis and Mansonella microfilariae (mf) carriers (125 persons with M. perstans and 92 with M. streptocerca), whereas the IgG4 ELISA showed a specificity of 81% in 137 M. perstans mf carriers and 85% in 94 M. streptocerca mf carriers. The sensitivity of Ov20/OvS1 in identifying onchocerciasis using the IgG4 ELISA was 75% for 103 O. volvulus mf carriers with the generalized and 89% for 44 patients with the sowda form of onchocerciasis. IgE antibodies against OvS1 were found in 95% of 39 patients with hyperreactive onchocerciasis but only in 15% of 47 persons with the generalized form. Thus, Ov20/-OvS1 appears a promising candidate antigen for the diagnosis of onchocerciasis and in particular for the detection of the sowda type of disease.

Humoral responses to a secretory Onchocerca volvulus protein: differences in the pattern of antibody isotypes to recombinant Ov20/OvS1 in generalized and hyperreactive onchocerciasis

The Onchocerca volvulus secretory protein Ov20/OvS1 represents a dominant antigen expressed in the infective larvae, microfilariae and adult stages of the parasite. The humoral responses to this protein have not yet been analysed in the polar clinical and immunological forms of onchocerciasis. Analysis by ELISA of class and subclass antibodies to Ov20/OvS1 in persons with the generalized or the hyperreactive form of onchocerciasis revealed similar strong responses of IgG1, IgG4 and IgM antibody levels in both forms of onchocerciasis and significant differences were observed in the IgE and IgA antibody classes. Computation of the ratios of antibodies showed that persons with the generalized form exhibited significantly higher ratios of IgG4 to IgG1, IgG4 to IgE, and IgM to IgE than patients with the hyperreactive form. To investigate the isotype recognition of antigenic sites on Ov20/OvS1 protein, three recombinantly expressed fragments (F1-3) of Ov20/OvS1 were probed using sera which strongly reacted with intact recombinant Ov20/OvS1. Epitope(s) on F1 comprising amino acid residues 1-63 were significantly recognized by IgG1 and IgE, while IgM recognized epitopes on all three fragments. The strongest reaction of IgM occurred with epitope(s) formed by residues 108-171 (F3). In contrast, IgG4 type antibodies were not reactive with either of the three OvS1 fragments, but they reacted with intact Ov20/OvS1 protein. Generalized onchocerciasis, unable to eliminate microfilariae, and hyperreactive onchocerciasis, with a high potency to eliminate or to reduce parasite loads, can be distinguished by a distinct pattern of isotype responses to Ov20/OvS1.

Endosymbiotic bacteria in worms as targets for a novel chemotherapy in filariasis

Endosymbiotic bacteria living in plasmodia or worm parasites are required for the homoeostasis of their host and should be excellent targets for chemotherapy of certain parasitic diseases. We show that targeting of Wolbachia spp bacteria in Onchocerca volvulus filariae by doxycycline leads to sterility of adult worms to an extent not seen with drugs used against onchocerciasis, a leading cause of blindness in African countries.

Targeting of Wolbachia endobacteria in Litomosoides sigmodontis: comparison of tetracyclines with chloramphenicol, macrolides and ciprofloxacin

Endobacteria of the genus Wolbachia in filarial nematodes are related to Rickettsiaceae and can be depleted by tetracycline antibiotics. This depletion blocks female worm development as well as early embryogenesis, in contrast to the currently used microfilaricidal ivermectin which blocks only the last stage of embryogenesis. Since targeting Wolbachia is becoming an area of research for the treatment of human filariases, it was investigated if antibiotics other than tetracyclines are able to deplete Wolbachia from filariae. BALB/c mice infected with the rodent filaria Litomosoides sigmodontis were treated with erythromycin, chloramphenicol or ciprofloxacin. All drugs were well resorbed and resulted in serum levels clearly above breakpoint levels for bacteria susceptible to the respective antibiotic. However, contrary to tetracycline, none of these antibiotics depleted Wolbachia or altered worm development and fertility, as evidenced by immunohistology, immunoelectron microscopy and semiquantitative PCR.

Long-term suppression of Mansonella streptocerca microfilariae after treatment with ivermectin

The long-term effect of a single oral dose of 150 microg/kg of body weight of ivermectin on Mansonella streptocerca microfilariae was studied in western Uganda. Before treatment, the geometric mean microfilaria density (mf) in 93 infected persons was 2.4 mf/mg of skin (range, 0.1-42.6). One year after treatment, 43 persons (46%) were microfilaria-negative, and the geometric mean in the remaining persons dropped significantly, to 0.7 mf/mg (range, 0.1-6.9). Thus, ivermectin is highly effective against M. streptocerca, and a single dose leads to a sustained suppression of microfilariae in skin. In Africa, ivermectin is used for mass treatment to control Onchocerca volvulus and Wuchereria bancrofti. Because these filarial parasites are often coendemic with M. streptocerca, the treated population may receive the additional benefit of suppression of M. streptocerca microfilariae.

Tetracycline therapy targets intracellular bacteria in the filarial nematode Litomosoides sigmodontis and results in filarial infertility

Intracellular bacteria have been described in several species of filarial nematodes, but their relationships with, and effects on, their nematode hosts have not previously been elucidated. In this study, intracellular bacteria were observed in tissues of the rodent parasite Litomosoides sigmodontis by transmission electron microscopy and by immunohistochemistry using antiendobacterial heat shock protein-60 antisera. Molecular phylogenetic analysis of the bacterial 16S ribosomal RNA gene, isolated by PCR, showed a close relationship to the rickettsial Wolbachia endobacteria of arthropods and to other filarial intracellular bacteria. The impact of tetracycline therapy of infected rodents on L. sigmodontis development was analyzed in order to understand the role(s) these bacteria might play in filarial biology. Tetracycline therapy, when initiated with L. sigmodontis infection, eliminated the bacteria and resulted in filarial growth retardation and infertility. If initiated after microfilarial development, treatment reduced filarial fertility. Treatment with antibiotics not affecting rickettsial bacteria did not inhibit filarial development. Acanthocheilonema viteae filariae were shown to lack intracellular bacteria and to be insensitive to tetracycline. These results suggest a mutualistic interaction between the intracellular bacteria and the filarial nematode. Investigation of such a mutualism in endobacteria-containing human filariae is warranted for a potential chemotherapeutic exploitation.

Ivermectin influence on the mast cell activity in nodules of onchocerciasis patients

Onchocercal nodules were stained immunohistochemically using antibodies specific for human mast cells and IgE to elucidate the localization and frequency of mast cells after a single oral dose of 150 microg/kg ivermectin. Tryptase-and chymase-positive mast cells occurred predominantly in mixed inflammatory infiltrates and perivascularly, and never adhered to adult worms or microfilariae. Up to three days after ivermectin, mast cells and IgE-positive cells were markedly increased in the capsular area of nodules containing female worms with embryos and microfilariae compared to untreated nodules. In the centre of these nodules, around the adult Onchocerca volvulus, we found many tryptase-positive cells. More mast cells were IgE-positive than in untreated nodules, equalling the number of tryptase-positive mast cells. There was a clear correlation between the appearance of mast cells and the attacks on damaged microfilariae by eosinophils and macrophages and in the vicinity of adult worms by neutrophils that occur soon after ivermectin treatment. Onchocercomata harbouring female worms with oocytes only revealed, after all treatment intervals, the same mast cell numbers as untreated nodules. In conclusion, during the first three days after administration, ivermectin produces increased numbers of mast cells in nodules harbouring females with embryos and microfilariae, probably as part of an allergic reaction to the attacked microfilariae. Four to 19 days after ivermectin the number of mast cells in the entire nodule is no longer elevated.

T cell responses in coinfection with Onchocerca volvulus and the human immunodeficiency virus type 1

Onchocerca volvulus and the human immunodeficiency virus (HIV) are two immunocompromising infectious agents of major public health concern in Uganda. To examine the effect of coinfection with O. volvulus and HIV on cellular immune responses, lymphocyte proliferative responses and cytokine production of peripheral blood mononuclear cells (PBMC) from persons infected with O. volvulus with and without HIV type 1 infection were compared. Proliferation of PBMC to PHA and tuberculin (PPD) in coinfection was less (P = 0.08, P < 0.01) than in O. volvulus infection. O. volvulus extract stimulated lymphocyte proliferation in microfilaria-negative and HIV-negative O. volvulus infection while only an inconspicuous response was observed in microfilaria-negative coinfection. After stimulation of PBMC with PPD, the production of interferon-gamma (IFN-gamma), interleukin (IL)-4 and IL-5-demonstrated in O. volvulus infection-were reduced in coinfection with HIV (P < 0.01). While both groups failed to produce IFN-gamma in response to O. volvulus extract, only O. volvulus infected persons generated pronounced IL-5 and low IL-4 levels (0.01 > P = 0.02). The cellular immune responses in coinfection suggested an HIV-related lack of specific reactivity to O. volvulus antigen and impairment of IL-4 and IL-5 production in addition to the lack of IFN-gamma response on antigenic stimulation.

The peroxidoxin 2 protein of the human parasite Onchocerca volvulus: recombinant expression, immunolocalization, and demonstration of homologous molecules in other species

The peroxidoxin protein of the filarial parasite Onchocerca volvulus (OvPXN-2) belongs to a group of highly conserved antioxidant molecules. For a more detailed characterization of this protein and for determination of its expression pattern the OvPXN-2 protein was recombinantly expressed as a His-tagged protein. Under reducing conditions the recombinant protein had an apparent molecular mass of 28 kDa. Considering the size of the His-tag and the FLAG epitope introduced to the recombinant protein, this size is in agreement with that of the native protein identified in O. volvulus extract. Antiserum raised against the recombinant protein was used for immunolocalization. In O. volvulus the antigen is predominantly expressed in the hypodermis and particularly the lateral and median chords show high levels of expression. The protein is also expressed strongly in the hypodermis of infective larvae and more weakly in microfilariae. Related cross-reacting proteins were detected in several Onchocerca species and other filariae. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in combination with Western blotting revealed proteins with almost identical mobility in extracts prepared from O. ochengi, O. gibsoni, and Dirofilaria immitis.

Immunoelectron microscopic evidence for release of eosinophil granule matrix protein onto microfilariae of Onchocerca volvulus in the skin after exposure to amocarzine

The involvement of eosinophils in the host reaction to microfilariae (mf) of Onchocerca volvulus was studied by immunohistochemistry and immunoelectron microscopy. Skin biopsies were obtained from patients after transepidermal administration of the microfilaricide amocarzine. At 20-28 h after the application of amocarzine, mf were degenerated or dead and a marked eosinophil-parasite adherence (EPA) reaction was seen, with intense staining for intra- and extracellular eosinophil granule proteins such as eosinophil cationic protein (ECP) surrounding the mf. Immunoelectron microscopically the eosinophil granule matrix in intact and necrotic eosinophils was specifically labeled, whereas granules whose matrix had dissolved showed no specific gold particle binding. As specific labeling was seen on lowly electron-dense material adjacent to matrix-depleted granules, the material was regarded as released eosinophil granule matrix material. Intact and necrotic eosinophils, matrix-containing as well as matrix-depleted eosinophil granules, and released eosinophil granule matrix material were observed on the surface of damaged mf and between collagen fibers. The coincidence of mf degeneration, EPA reaction, and release of eosinophil granule matrix material on damaged mf and collagen fibers indicated a role of eosinophils and eosinophil granule matrix protein in the host reaction to mf after amocarzine application.

Mast cells in onchocercomas from patients with hyperreactive onchocerciasis (sowda)

In onchocerciasis, variations of the host's immune responsiveness produce a spectrum of clinical manifestations ranging from the common generalized to the rare hyperreactive form (sowda). For further characterization of the immune response, the localization and frequency of mast cells in onchocercomas from untreated and ivermectin-treated patients with hyperreactive onchocerciasis from Liberia and the Yemen were analysed and compared to the generalized form by immunohistochemistry with antibodies specific for human mast cell tryptase and chymase, histamine and IgE. The nodules were selected with special regard to only one pair of live, microfilariae-producing Onchocerca volvulus. Throughout the nodular tissue of the hyperreactive form, mast cells accumulated in the strong inflammatory infiltrates, especially near eosinophils and around cellular attacks on microfilariae as well as perivascularly. Their number was significantly higher in the whole nodular tissue compared to the generalized form. The highest numbers occurred in the nodule centre. Mast cells carried IgE and appeared activated. No mast cells were observed in the cystic parts or attached to adult worms or microfilariae. In onchocercomas, 1 and 3 days after treatment with ivermectin, microgranuloma formation by eosinophils and macrophages around damaged microfilariae was enhanced and accompanied by numerous mast cells. Attacks of neutrophils were also pronounced, but attacks by mast cells were not observed. In conclusion, hyperreactivity against microfilariae in onchocercomas clearly correlates with a strong mastocytosis and IgE production parallel to tissue eosinophilia.

Ivermectin distribution using community volunteers in Kabarole district, Uganda

Ivermectin mass distribution for the control of onchocerciasis in Uganda began in 1991. This report describes a community based ivermectin distribution programme covering two foci in the Kabarole district which have an estimated 32,000 persons infected and another 110,000 at risk. Through nodule palpation in adult males, 143 villages were identified where nodule prevalence exceeded 20%. Skin snips were also taken from a sample of the population to measure changes in community microfilarial load (CMFL) with treatment. The delivery programme was integrated into the district health management structure, and used community volunteers supervised by medical assistants from adjacent health facilities for annual ivermectin distribution campaigns. After initial efforts by the community to support distributors in-kind proved inadequate, ivermectin distributors earned money retailing condoms as part of the social marketing component of district STD/AIDS programme. Reduction in the CMFL ranged from 40-62% twelve months after the second ivermectin treatment in three villages, and from 69-84% six months after the fourth round of treatment in two villages. After four years of treatment, 85% of eligible persons were receiving ivermectin from community volunteers in each treatment cycle. Drop out rates among volunteers did not exceed 20% over the four years reported here. The direct cost of treatment was US $0.29 per person. Among the reasons for low per-person treatment costs were the strong supervisory structure, the presence of health centres in the foci and a well developed and capable district Primary Health Care management team.

Detection of the filarial parasite Mansonella streptocerca in skin biopsies by a nested polymerase chain reaction-based assay

To differentiate the skin-dwelling filariae Mansonella streptocerca and Onchocerca volvulus, a nested polymerase chain reaction (PCR) assay was developed from small amounts of parasite material present in skin biopsies. One nonspecific and one specific pair of primers were used to amplify the 5S rDNA spacer region of M. streptocerca. Biopsies with different microfilaria densities obtained from 104 Ugandans living in an area endemic for M. streptocerca were tested using both the nested PCR assay and standard parasitologic assessment of microfilariae. All 82 samples from microfilaria carriers were positive when tested using the nested PCR assay. In addition, M. streptocerca DNA could be detected in 16 samples thought to be microfilaria negative. Furthermore, six days following ivermectin treatment, M. streptocerca DNA was found in 12 of 14 microfilaria-negative biopsies. Control skin samples from patients infected with O. volvulus were all negative in the nested PCR assay. This assay improves the diagnosis of M. streptocerca and will facilitate further epidemiologic studies.

Mast cell distribution in nodules of Onchocerca volvulus from untreated patients with generalized onchocerciasis

Onchocercomata with a defined worm population were analysed to elucidate the distribution of mast cells. Nodules with live females were classified according to the presence or absence of microfilariae. Immunohistochemical staining was performed using antibodies specific for mast cells or IgE. Mast cells appeared singly or in diffuse accumulations perivascularly and in inflammatory infiltrates between adult Onchocerca volvulus and in the capsular area. No mast cells were detected in cystic parts. Only few, scattered mast cells were found in the fibrous zone around the adult worm. They were increased with stronger infiltration and hence, related to the inflammatory cells. Mast cells were never localized directly at adult worms or microfilariae. A correlation of the mast cell distribution to the occurrence of eosinophils was observed regarding higher numbers of mast cells and eosinophils in nodules with microfilariae-producing females. Nodules with single males revealed higher numbers of mast cells than nodules with non-producing females, although both contained very few eosinophils. Onchocercomata with dead worms contained significantly more mast cells than those with live filariae. In conclusion, the localization and frequency of mast cells is contingent on the vitality and productivity of the worms and therefore, indirectly and directly on the release of O. volvulus antigens.

Immunohistological studies on macrophages in lymph nodes of onchocerciasis patients after treatment with ivermectin

The role of macrophages in the killing and elimination of microfilariae (mf) was studied immunohistologically in 14 lymph nodes from 10 patients with generalized onchocerciasis 20-68 h after treatment with a single oral dose of 150 microg/kg ivermectin. Mf with signs of damage at light microscopical level were surrounded by a cellular infiltrate comprising macrophages, eosinophils and neutrophils, whereas light microscopically intact mf mostly showed no cellular reaction. Resident mature macrophages expressing the CD 68 epitope usually neither migrated nor attached to damaged mf, especially on the first and second day after ivermectin treatment. However, many young invading macrophages labelled for the L1 protein (antibodies 27 E 10, MAC 387, S 36.48 and 8.5C2) were found within the cellular infiltrate around damaged mf and in adherence to the mf in all lymph nodes after ivermectin treatment. Free L1 protein was observed on the cuticle of the mf. The attacking macrophages contained increased amounts of the enzymes lysozyme, alpha-1-antichymotrypsin and alpha-1-antitrypsin compared to resident macrophages. Free enzymes were found on the cuticle of the mf and around them, indicating a role of these enzymes in the inflammatory reaction to the parasites. The attacking macrophages were strongly labelled for human HLA-DR and they showed further an increased expression of the complement receptors CR1 (CD 35) for C3b and CR3 (CD 11b) for C3 bi in comparison to resident macrophages and thus were considered as activated macrophages. Rarely fragments of mf were seen within multinuclear macrophages. We conclude that young activated macrophages play a major role in the elimination of mf transported to the regional lymph nodes after ivermectin treatment. The immunohistological findings are in accordance with the assumption that these activated macrophages together with granulocytes contribute to the killing of the damaged mf. They also help to limit the damage of the host tissue by release of alpha-1-antichymotrypsin and alpha-1-antitrypsin.

Onchocerca volvulus: immunohistochemical and immunoelectron microscopical distribution of a polyamine oxidizing enzyme

We studied the distribution of a polyamine oxidizing enzyme (PAO) in Onchocerca volvulus and other nematode parasites by immunohistochemistry and electron microscopy with immunogold technique using a polyclonal antiserum raised against purified PAO from Ascaris suum. In adult O. volvulus the protein was localized in the outer zone and the area of the basal labyrinth of the hypodermis and occasionally in the outer zone of the uterine epithelium. Further, the fluid in the body cavity was strongly stained. No specific labelling was observed in the cuticle, muscles, epithelia of intestine, ovaries, testis and vas deferens or in sperm, oocytes and embryos. Third-stage larvae of O. volvulus in Simulium soubrense showed strong staining; the same was observed in Anisakis sp. larvae, where the inner and outer zone of the hypodermis were strongly labelled. All mature, intact and dead microfilariae in nodules, skin and lymph nodes were well stained and it was possible to show that the cytoplasm of the hypodermal cells, but not the mitochondria, nuclei or other organelles of muscle cells, was preferentially labelled by immunogold particles. Investigation of adult A. suum presented specific labelling of the hypodermis, but the basal labyrinth was more strongly marked than the outer zone.

Treatment of human Mansonella streptocerca infection with ivermectin

We studied the short-term effects of a single dose of 150 micrograms/kg body weight ivermectin on Mansonella streptocerca in an area endemic for streptocerciasis, but not for onchocerciasis, in western Uganda. Six and 12 days after treatment no microfilaria (mf) were found in the skin of 53 out of 96 mf carriers living in 3 villages, and the geometric means of the mf densities of remaining mf carriers were only 33-40% of pretreatment levels. This reduction of mf density was highly significant (P < 0.0001). Immunohistological examination of skin biopsies showed degenerated and disintegrating mf surrounded by activated eosinophils (positive for activated cationic protein), macrophages, and neutrophils (positive for myeloperoxidase and defensin) on day 6 after treatment. Remarkable was the invasion of young, L1 protein-positive macrophages and the release of neutrophil defensin as signs of acute inflammation. We conclude that ivermectin has a strong microfilaricidal activity against M. streptocerca. Common adverse effects were increased pruritus and acute papular dermatitis in 45% of 86 mf carriers on day 6 after treatment. No serious adverse side-effects were noticed in about 700 treated persons.

Distribution of mast cells and their correlation with inflammatory cells around Onchocerca gutturosa, O. tarsicola, O. ochengi, and O. flexuosa

In recent years, bovine Onchocerca species have been used as models for human onchocerciasis in drug screens. They have been suggested for immunology studies and evaluation of vaccine candidates. Therefore, mast cells and their association with other inflammatory cells were studied in five onchocercal species of cattle and deer using immunohistology. Intact mast cells occurred in large numbers in the capsule and septae of nodules, in fibrous tissue adjacent to nonnodular worms, and perivascularly. Inactive and, more frequency, activated and degranulating mast cells were observed within infiltrates in the nodule center or around nonnodular filariae. They were not detected in direct contact with the cuticle of adult worms or of microfilariae or among the macrophages, giant cells, and neutrophils forming the innermost layer around the worms. Eosinophils, but not mast cells, were obviously associated with microfilariae-producing females. The distribution, frequency, and activity of mast cells were similar for all five species and O. volvulus.

Occurrence and diagnosis of Mansonella streptocerca in Uganda

During filaria surveys Mansonella streptocerca was found for the first time in Uganda, in 12 widely scattered villages in the Bundibugyo district between the Ruwenzori mountains and the Ituri forest, an area not endemic for Onchocerca volvulus. The crude prevalence in 806 examined adult persons ranged from 5 to 89% with an average of 61%. In 148 children the prevalence was 36%. The geometric mean of microfilaria (mf) densities in adult mf carriers was 1.7 mf/mg skin and the community microfilarial loads ranged from 1.0 to 13.7 mf/skin snip. In 476 persons skin snips from the shoulder contained mf in 58% and those from the buttocks in 48%. Skin snips from 68 persons digested with collagenase showed that only 30-37% of the mf emerged during 24 h incubation at 30 degrees C in isotonic salt solution. An itching acute or more often chronic papular dermatitis, predominantly on the upper parts of the body, was the typical skin lesion observed in 24% of 177 M. streptocerca mf carriers.

Serum levels of eosinophil cationic protein, eosinophil-derived neurotoxin and myeloperoxidase in infections with filariae and schistosomes

The serum levels of three major granulocyte proteins were measured in patients with onchocerciasis, bancroftian filariasis and intestinal schistosomiasis and compared to controls from patients with malaria, Africans living in areas not endemic for these infections and healthy Germans. The investigation comprised the determination of the eosinophil granule proteins eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN/EPX), and the neutrophil/monocyte granule protein myeloperoxidase (MPO). ECP and EDN/EPX levels were found elevated only in the three helminth infections that are associated with eosinophilia, while MPO was found elevated in all tested disease groups. The levels of eosinophil granule proteins observed in the helminth diseases by far exceeded those described for bronchial asthma and atopic dermatitis. ECP, EDN/EPX and MPO serum levels reflect the ongoing disease and are related to functional activity of the respective leukopoetic system. ECP and EDN/EPX appear to be markers of the eosinophil effector system and MPO a marker of the neutrophil and/or monocyte/macrophage effector system. Significantly higher ECP levels in chronic hyperreactive onchodermatitis (sowda) versus generalized onchocerciasis seem to reflect an augmented degree of antigenic stimulation, eosinophil activation and eosinophil turnover rates, indicating a more active mechanism of parasite clearance in sowda patients.

Immunohistological studies on an Onchocerca volvulus ankyrin (EI)

The distribution of an Onchocerca volvulus ankyrin, designated E1, was studied in different O. volvulus stages and other helminths by immunohistochemistry using rabbit antibodies raised against the recombinant E1 protein. In adult O. volvulus the protein designated E1 was localized to the extracellular clefts as well as to the cytoplasm adjacent to the cell membrane in the area of the basal labyrinth in hypodermis, intestine and uterus and to a lesser extent in oviduct and vas deferens. Neuronal cell bodies were also labelled. No labelling of the basal laminae, muscles or epithelia of ovary or testis was observed. Detection of the E1 protein was associated with embryonic development. Germ cells and early morulae showed no reaction; labelling was first seen in late morulae, corresponding to the stage of gastrulation, and increased in the following embryonic stages. In microfilariae the nerve ring and the cephalic space, which represents the anterior nerve-enriched portion of the body, were labelled. In third-stage larvae of O. volvulus labelling was associated with the hypodermis, and in those of Anisakis sp. the cytoplasm adjacent to the membrane of the excretory gland cell and the basal labyrinth of the hypodermis were labelled. Following anthelminthic treatment a disruption of the labelling pattern of the E1 protein was observed in adult O. volvulus with leakage of the protein into neighbouring areas. Damage to the worm was associated with reduction and finally loss of E1 protein labelling. No E1 protein was detected in dead adult worms, embryos or microfilariae. Labelling of the same organs was observed in 8 other Onchocerca species and in several other nematodes, but no reaction was seen in trematodes. The results indicate that the EI protein is associated with neuronal structures of O. volvulus, that its presence is developmentally regulated and that it has cross-reactive homologues in other nematodes. The results suggest that E1 is a functional protein. It may be useful for the assessment of parasite damage and death as well as in the characterization of the filarial nervous system.

Neutrophil granule proteins: evidence for the participation in the host reaction to skin microfilariae of Onchocerca volvulus after diethylcarbamazine administration

The participation of neutrophil granulocytes in the cellular reaction to skin microfilariae of Onchocerca volvulus was studied by immunohistochemistry. Skin biopsies were obtained from adult Liberian and Ugandan patients with generalized onchocerciasis after exposure to topically applied diethylcarbamazine (DEC) and from untreated patients. After DEC many damaged microfilariae were observed either in dermal infiltrates or in epidermal microabscesses consisting both of neutrophils and eosinophils. Infiltrates and microabscesses contained some intact granulocytes and many neutrophils releasing myeloperoxidase, elastase, lactoferrin, defensin, lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin. Eosinophils discharged peroxidase and cationic proteins. Released granule proteins and remnants of disrupted granulocytes were found on the surface and in close proximity of damaged microfilariae in dermal infiltrates and epidermal microabscesses. In larger microabscesses neutrophils were predominant. These observations show that neutrophils and not only eosinophils recruit, accumulate, localize around and release their helminthotoxic granule proteins such as myeloperoxidase onto or closely around skin microfilariae of O. volvulus after topical DEC administration. The association between these processes and the damage of the microfilariae indicated that neutrophils together with eosinophils attack and damage microfilariae of O. volvulus after DEC treatment in the skin.

Sensitivity of a polymerase chain reaction-based assay to detect Onchocerca volvulus DNA in skin biopsies

A polymerase chain reaction (PCR) of a 150-bp tandem repeat of Onchocerca volvulus (O-150) combined with Southern-blot hybridization to species-specific DNA probes was employed for DNA detection. O-150 was amplified from parasites originating from Uganda, Benin, Cameroon, Liberia, Ghana, Burkina Faso, Mali, and Zaire and was successfully hybridized to digoxigenin-labeled oligonucleotides. To investigate the sensitivity of the PCR, 2 skin biopsies were taken from each of 227 persons from Uganda with proven O. volvulus infections but with low microfilaria (mf) densities due to ivermectin treatment. One biopsy was tested by PCR and the other was digested using collagenase to assess the total number of mf. The PCR revealed 76.2% of the samples to be positive, and the collagenase method showed that 78.9% were positive, indicating similar sensitivity for the two methods. It is probable that for both techniques the biopsy must contain at least one live mf or fragments of a dead mf. In this study, no free or circulating O. volvulus DNA could be detected in skin biopsies by PCR.

Strain differentiation of Onchocerca volvulus from Uganda using DNA probes

Polymerase chain reaction (PCR) combined with non-radioactive DNA hybridization was applied for the detection and characterization of a 150 bp tandem repeat of Onchocerca volvulus. DNA of worms from western Uganda was amplified and then probed with a digoxygenin-labelled oligonucleotide, specific for the forest form of O. volvulus and compared to samples from various African countries. Hybridization was only observed with PCR products from the forest in Liberia, south-eastern Ghana, Benin and southern Cameroon, but not with worms from Uganda or the savannah in Burkina Faso and northern Ghana. A nested PCR using primers derived form the forest form-specific DNA sequence confirmed these results. Morphometric studies revealed length differences between the microfilariae of Ugandan O. volvulus to those of West Africa, especially to those of the savannah in Burkina Faso. It is concluded that the forest/savannah classification of O. volvulus from West Africa is not suitable for Simulium neavei-transmitted O. volvulus from Uganda.

Molecular cloning, expression, and localization of E1, an Onchocerca volvulus antigen with similarity to brain ankyrin

Protective immunity against human onchocerciasis may best be reflected by the existence of individuals who in spite of exposure to the filarial nematode Onchocerca volvulus do not develop disease (putatively immune). We observed preferential recognition of an O. volvulus antigen of approximately 90 kDa by sera from putatively immune individuals compared with sera from diseased individuals. Screening of an adult worm cDNA library with one serum recognizing this antigen almost exclusively led to the identification of a full length clone of 2043 base pairs designated E1. The open reading frame of 462 amino acid residues shows similarity to human brain ankyrin. E1 appears to represent a small transcript of the O. volvulus ankyrin gene. The nonfusion protein obtained by expression of the complete E1 cDNA exhibits an apparent molecular mass of 90 kDa on SDS-polyacrylamide gel electrophoresis. An antiserum against the recombinant protein reacts with the 90-kDa antigen in O. volvulus extract. In O. volvulus, E1 was localized in the neuronal cell bodies, the nerve ring, and the extracellular clefts of the basal labyrinth. These results identify an ankyrin-related O. volvulus protein as an immunogen to putatively immune individuals, suggesting that neuronal proteins may be important targets for immunity against O. volvulus in vivo.

Dependence of eosinophil granulocyte infiltration into nodules on the presence of microfilariae producing Onchocerca volvulus

Onchocercomata with a single live or dead worm were analyzed to elucidate the infiltration of eosinophils. Females were classified according to the presence or absence of microfilariae in their uteri and in the nodular tissues. Immunohistochemical staining was performed using antibodies against eosinophil cationic protein, peroxidase, and major basic protein. Very few eosinophils were detected in nodules containing females without microfilariae or male or dead worms only, whereas eosinophils were abundant in all nodules with females producing microfilariae. The occurrence of eosinophils was not related to the age of the worm. Occasionally, degenerated or dead microfilariae attacked by activated eosinophils were found. By examination of onchocercomata with or without microfilariae from the same patient, it was excluded that the occurrence of eosinophils was dependent mainly on the host's immune status. In conclusion, live adult Onchocerca volvulus do not elicit an invasion of eosinophils as long as they do not produce microfilariae. The absence of eosinophilia does not exclude onchocerciasis.

Prevalence of Mansonella perstans in western Uganda and its detection using the QBC-fluorescence method

The prevalence of the apathogenic filaria Mansonella perstans was studied in four parishes in western Uganda as part of an onchocerciasis control programme to avoid futile treatment. Blood samples from 1543 persons aged over 14 years from 19 villages were examined for the presence of microfilariae using a modified Knott method. The prevalence of microfilaraemic persons ranged between the parishes from 39% (95% CI 35.9-42.0%) to 81% (95% CI 76.2-84.8%). With exception of single microfilariae of Onchocerca volvulus no other filaria species was detected. Onchocerciasis mass treatment campaigns did not reduce the prevalence of M. perstans infection, since 6-12 months after treatment with a single dose of 150 micrograms/kg ivermectin the prevalence in 124 persons was about the same as before treatment. The QBC-fluorescence technique was employed for the detection of microfilariae in samples from outpatients of the government hospital in Fort Portal: in 16% of 120 children and 24% of 369 adults microfilariae of M. perstans were detected.

Impaired antibody responses and loss of reactivity to Onchocerca volvulus antigens by HIV-seropositive onchocerciasis patients

The impact of concomitant human immunodeficiency virus (HIV) infection on the antibody response of onchocerciasis patients to Onchocerca volvulus antigens (OvAg) was studied by Western blotting and enzyme linked immunosorbent assay (ELISA). Immunoglobulin G (IgG) antibodies in sera from 45 HIV-sero-positive O. volvulus microfilariae (mf) carriers (HIV+/Ov+) recognized significantly fewer distinct O. volvulus antigenic bands, and responded less frequently to all detected bands compared to sera from 61 matched HIV-seronegative mf carriers (HIV-/Ov+). 29% of 31 follow-up sera from the HIV+/Ov+ patients failed to react to many of the antigenic bands recognized by initial sera from the same patients. Among 4 HIV+/Ov+ persons examined for total CD4+ cells, loss of reactivity corresponded with low CD4+ total cell counts. In an OvAg ELISA, sera from the HIV+/Ov+ individuals had significantly lower IgG+IgM antibody levels than sera from the HIV-/Ov+ persons, and the sensitivity of the assay was 87% for the HIV+/Ov+ subjects compared to 100% for those who were HIV-/Ov+. It is concluded that HIV-infected onchocerciasis patients exhibit significantly impaired antibody responses to O. volvulus antigens, and tend to lose their reactivity to these antigens over time due to immune response abnormalities caused by the concomitant HIV infection.

Ivermectin treatment of hyperreactive onchodermatitis (sowda) in Liberia

Seventeen male and 39 female Liberian patients, one third of them children, were diagnosed as having hyperreactive onchodermatitis (sowda). They presented with itching (98%), asymmetric (98%), chronic onchodermatitis (median 5 years), and swelling of femoral lymph nodes (89%). The geometric means of the microfilaria (mf) densities were 1.0 mf/mg in children and 0.7 mf/mg in adults. These patients not only suffered from their skin lesions, and severe itching resulting in disturbance of sleep but also from social stigmata. They urgently needed treatment. Ivermectin was administered as a single oral dose of 150 micrograms/kg body weight. The following adverse effects were observed in 30 patients within the first 72 hours after ivermectin treatment: increase of pruritus (93%), aggravation of dermatitis (73%), fever (25%), headache (20%), myalgia (20%), painful swelling of lymph nodes (13%) and severe swelling of arm or leg (10%). Symptomatic therapy was sufficient. No dangerous or life-threatening side effects were observed. At follow-up examinations 1-2 months after ivermectin treatment, the prevalence of mf carriers had decreased from 100% to 19%. Seventeen out of 18 patients felt their dermatitis had improved. Evaluation of the dermatitis by a physician using a score from 0 (no dermatitis) to 9 (severe dermatitis) revealed a reduction of the score from 4.3 before treatment to 0.7 (84%) after ivermectin. In contrary, at the follow-up examination of 16 patients 6-12 months after ivermectin some recrudescences were observed. In this group the prevalence of mf carriers was 47%, 13 out of the 16 patients felt their skin lesions had improved and the score had decreased from 2.2 to 0.5 (77%). Consequently, it is recommended to administer ivermectin to patients with hyperreactive onchodermatitis every 3-4 months.

The chemotherapy of onchocerciasis XX: ivermectin in combination with albendazole

Ivermectin is a potent microfilaricide that also blocks microfilarial release while albendazole is toxic to all intrauterine stages. We investigated whether their combination would permanently sterilize the adult worms. In the first open phase, all 69 patients received 150 micrograms/kg of ivermectin. In the second double-blind phase one week later, 35 patients were randomized to receive 800 mg of albendazole with a fatty breakfast for three consecutive days while 34 patients received matching placebo tablets. Detailed clinical and laboratory examinations were done before treatment and were repeated at intervals over one year. Nodules were excised at three and six months. There was a rapid reduction in skin microfilariae, maximal at four weeks (99.9%). Counts increased subsequently and were between 11 and 18% of initial values at one year. Nodule histology showed no macrofilaricidal activity of the combination. A high proportion of the stretched intrauterine microfilariae were degenerate in both groups. Anterior chamber microfilarial counts were unchanged until day 18 and then fell successively. Low levels persisted in several patients at one year. Dead corneal microfilariae and corneal punctate opacities increased initially, fell with time and then disappeared in most patients. Systemic and ocular reactions were mild to moderate and biochemical abnormalities were minor. A pronounced posttreatment eosinophilia subsided by day 30. There was no significant difference between the two groups in clinical and laboratory tolerance or in alterations in skin and ocular parasites and no important differences in the effect on the adult worms. The combination of ivermectin with albendazole given one week apart is well tolerated but produces no additional effect against Onchocerca volvulus when compared to ivermectin given alone.

Prevalence and risk factors of HIV-1 infection in three parishes in western Uganda

A population-based serosurvey was conducted to determine the HIV-1 prevalence and to evaluate various risk factors in three parishes in western Uganda. Adults over 14 years were examined in all 13 villages of Kigoyera parish far from Fort Portal, in two villages of Kyamukoka parish closer to Fort Portal and in the four fishing villages of Ntoroko parish at Lake Albert with a high population mobility. Personal interviews and HIV serology using ELISA and Western blot were performed. Sera showing at least two envelope bands in the Western blot were considered as positive. The coverage of the registered eligible population was 74% in Kigoyera, 67% in Kyamukoka and 25% in Ntoroko. The prevalence of HIV was 4% (97 of 2267 persons examined, 95% CI 3.4-5.1%) in Kigoyera, a typical rural area. Whereas it was 13% (53 of 393 persons examined, 95% CI 10.1-16.9%) in Kyamukoka near to the district capital and exceptionally high with 24% (96 of 399 persons examined, 95% CI 19.9-28.3%) in the comparatively isolated fishing villages of Ntoroko. In a multivariate model the infection risk for HIV was in Kyamukoka two and in Ntoroko five times higher than in Kigoyera. Among the two main ethnic groups one had a significantly lower risk to acquire HIV infection than the other group.

CONCLUSIONS

Because of their large proportion of migrating persons the fishing villages presented populations with high risks for HIV infection. The ethnic composition of the village population, representing group specific sexual behaviour, was a risk factor for HIV infection.

Human autoantibody to defensin: disease association with hyperreactive onchocerciasis (sowda)

Chronic hyperreactive onchodermatitis (sowda) is a severe form of onchocerciasis observed in a subset of individuals infected with the filarial nematode Onchocerca volvulus. SDS-PAGE and immunoblot analyses of O. volvulus adult worm extracts were used to characterize the antigens of the marked antibody response of sowda patients. One 2.5-kD antigen was recognized by sera from all 35(100%) sowda patients that were studied. In comparison, only 7 of 44 (16%) patients with generalized onchocerciasis and 11 of 21 (52%) of exposed individuals with no microfilariae in skin snips and no signs of disease showed reactivity to this antigen. Microfilaricidal treatment of sowda patients with improvement of the clinical status was associated with a decrease or disappearance of antibodies to the 2.5-kD antigen. Amino acid sequencing of the antigen indicated identity to human defensins 1-3 of neutrophils. Defensin was demonstrated by immunohistochemical staining in onchocercal nodules on the surface of adult filariae and in the surrounding tissue. A similar staining pattern was observed for other proteins present in neutrophils such as myeloperoxidase, elastase, and the L-1 protein complex (MRP 8/MRP 14), indicating that neutrophils, macrophages, and their proteins predominate in the environment adjacent to the worms. These results demonstrate an association between the presence of autoantibodies to defensins and an infectious disease of known etiology. The association with a particular form of onchocerciasis, sowda, suggests a link between formation of autoantibodies to defensin and enhanced immune reactivity towards the parasite.

A putative protein related to human chemokines encoded antisense to the cDNA of an Onchocerca volvulus antigen

Chronic hyperactive dermatitis (sowda) in humans infected with the filarial parasite Onchocerca volvulus appears to reflect a hyperresponsiveness to parasite antigens. To identify antigens which play a role in this hyperresponsiveness an expression cDNA library of adult O. volvulus was screened with sera from patients with sowda. One further characterized cDNA clone, S1, consisting of 723 bp, surprisingly shows open reading frames (ORF) in both orientations. While a single ORF of 171 amino acids is present in sense orientation, a putative ORF of 95 AA is found in antisense orientation (aS1). Whereas no homologies to known proteins are found in S1, the sequence of aS1 shows a striking structural homology to human CC chemokines. The genomic organization of the coding region of aS1 shows the conserved three exon/two intron structure of the CC chemokine family. In adult worms transcription of mRNA corresponding to S1 but not to aS1 was detected. Expression of S1 as a non fusion protein and Western blot analysis revealed antibody recognition by all sera from patients with sowda, by 60% of sera from patients with the generalized form of onchocerciasis, but not by sera of exposed individuals with no evidence of onchocerciasis. IgG subclass analysis showed that IgG3 reactivity was restricted to sowda sera. In adult worms the S1 protein was localized to the hypodermis. Here we present the cloning and characterization of an O. volvulus antigen, which may be useful in the diagnosis of onchocerciasis. Furthermore, the results suggest the presence of a gene structurally related to human inflammatory cytokines in antisense orientation, raising the question of bidirectional transcription in O. volvulus.

The chemotherapy of onchocerciasis XVIII. Aspects of treatment with suramin

We report the clinical and parasitological effects of a modified treatment regimen for suramin. Twenty adult males received up to 5 g (72.5 to 84.7 mg/kg) of suramin over 36 days. Detailed clinical and laboratory examinations were done before treatment and then at intervals over 2 years. Nodules were removed at 6, 13, 26 and 52 weeks for histology. Systemic tolerance was good. Anterior segment inflammation was however common and 2 patients required intervention to prevent posterior synechiae. No new posterior segment lesions developed; a rare improvement occurred in one patient with papillitis. Proteinuria, mostly mild, occurred in nearly all patients. Previously unreported renal glycosuria was documented in one patient. Microfilariae in the skin and anterior chamber did not change significantly for 5 or more weeks after which rapid reductions occurred. Ocular parasites were absent at 2 years and skin microfilariae were near zero. Peripheral blood eosinophil counts fell in parallel with those of microfilariae in the skin and anterior chamber and were normal at one and two years. These findings at 2 years may provide indirect evidence of a macrofilaricidal or a permanent chemosterilant effect on the adult worms. Nodule examination revealed an embryotoxic effect from week 6, a lethal effect on the male worms from month 3 and on the female worms from month 6 after treatment started. At one year 34% of the female worms examined were alive. Thus total doses of suramin in the range 72.5 to 84.7 mg/kg have only a modest lethal effect on the female worms. Suramin remains a restricted drug and a suitable replacement is urgently needed.

Immunodiagnostic studies on Onchocerca volvulus and Mansonella perstans infections using a recombinant 33 kDa O. volvulus protein (Ov33)

A total detergent-soluble extract of adult female Onchocerca volvulus (OvAg) and a recombinant O. volvulus protein (Ov33) linked to glutathione-S-transferase (GST) were compared with regard to their serodiagnostic suitability for differentiating between O. volvulus and Mansonella perstans infections in a region endemic for both filarial worms in western Uganda. Using OvAg in an enzyme-linked immunosorbent assay (ELISA), 98.8% sensitivity was obtained examining 84 O. volvulus microfilariae (mf) carriers living in the hyperendemic area. However, 5 of 18 (28%) sera from M. perstans mf carriers without O. volvulus mf, from another area hypoendemic for O. volvulus, cross-reacted with OvAg. Using the recombinant antigen Ov33-GST in an ELISA and Western blot assay, sensitivity for O. volvulus remained high (97.2% and 98.8% respectively) while none of 90 sera from M. perstans mf carriers reacted positively. Both antigens were used to examine a batch of sera from 260 persons living in the onchocerciasis hyperendemic area who did not have mf in their skin snips (9.5% of 2728 persons examined); 116 of these sera (44.6%) were positive in the OvAg ELISA, compared to 85 (32.7%) and 69 (26.5%) which were positive in Ov33-GST ELISA and Ov33-GST Western blot, respectively. Reaction with GST alone was minimal. The recombinant antigen Ov33 efficiently differentiates between O. volvulus and M. perstans infections, and is sensitive when used to detect patent and prepatent or low-level O. volvulus infections.

Light and electron microscopy studies on Onchocerca jakutensis and O. flexuosa of red deer show different host-parasite interactions

Adult filariae of two intranodular Onchocerca species of red deer (Cervus elaphus) were examined at the ultrastructural level. In all, 90 nodules of O. flexuosa and 20 nodules of O. jakutensis were studied by histology. O. jakutensis caused cystic and pus-filled nodules in which the female and male worms were motile. Female worms possessed a thick cuticle and a well-developed somatic musculature. The basal lamina of the muscular syncytia was connected with the transhypodermal fibers through long protrusions. The epicuticle had only few protuberances and no visible surface coat. Female O. flexuosa showed morphological features similar to those of other intranodular filariae. A surface coat could not be detected. In 24% of 33 nodules with young live female worms and 40% of 38 nodules with older live female O. flexuosa the worms were surrounded by giant cells apparently attacking a cuticle. This was found even in nodules obtained from animals no older than 9 months. It is probable that the lack of a surface coat protecting the female worm and the inability to move due to the reduced somatic muscles lead to an early elimination of O. flexuosa by the host's immune system.

The chemotherapy of onchocerciasis XVII. A clinical evaluation of albendazole in patients with onchocerciasis; effects of food and pretreatment with ivermectin on drug response and pharmacokinetics

Three pharmacokinetic studies were conducted in Ghanaian patients in support of investigations of albendazole and its combination with ivermectin in the treatment of onchocerciasis. These included dose-finding studies, investigations into the influence of a fatty meal on the relative bioavailability of albendazole as assessed by the measurement of concentrations of albendazole sulphoxide and the effect of prior treatment with ivermectin on antiparasitic efficacy and plasma concentrations of albendazole suphoxide. Increasing the dose of albendazole from 800 mg x 3 daily to 1200 mg x 3 daily produced no additional antiparasitic effects although plasma concentrations of albendazole sulphoxide were increased in proportion to dose size. Moreover, the plasma concentration vs time profiles suggest that most of the effects observed may have been due to the first 800 mg dose. Administration of ivermectin had no effect on the pharmacokinetics of albendazole sulphoxide and there was no additive effect on the parasite. Albendazole was well tolerated and its administration 5-7 days after ivermectin produced little additional reaction. Although it is not macrofilaricidal, it does possess important chemosterilant properties which are enhanced by its administration with a fatty breakfast. Under these conditions, the relative bioavailability of albendazole is increased four-fold. These studies support further work with albendazole administered with food either as a single dose, as multiple single doses repeated at intervals of several months and its coadministration with ivermectin. They also encourage the belief that a more potent and bioavailable benzimidazole may be macrofilaricidal or a permanent chemosterilant for Onchocerca volvulus on single dosage.

Lymph nodes of onchocerciasis patients after treatment with ivermectin: reaction of eosinophil granulocytes and their cationic granule proteins

Lymph node and skin biopsies from Liberian patients with generalized and localized (sowda) onchocerciasis were studied 12-68 hours after oral administration of ivermectin at a single dose of 150 micrograms/kg body weight. Electron microscopic examination and immunohistochemical staining with antibodies against two different forms of eosinophil cationic protein (ECP EG1, ECP EG2), eosinophil peroxidase (EPO) and cationic leukocyte antigen (CLA) were performed. Following their disappearance from the skin, a large number of microfilariae was found in the regional lymph nodes. The lymph nodes from treated patients had over ten times more eosinophils compared to those from untreated persons with a peak of eosinophil density at 40-48 hours after treatment. Degenerating microfilariae in the lymph nodes were encircled by eosinophils, which showed positive immunostaining for ECP, EPO or CLA. Intra- and extracellular eosinophil granules revealed a great variation in their condition. In some specific granules a variety of structural alterations in the crystalloid cores occurred while in others different stages of deficiency in the matrix electron density were observed. The frequent necrosis of eosinophils in the immediate vicinity and at some distance from the microfilariae, with subsequent release of granules and the deposition of toxic cationic granule proteins onto the microfilarial cuticle during the eosinophil-parasite adherence reaction, demonstrated the function of these proteins in the ivermectin-reinforced killing of microfilariae in lymph nodes.

Parasitological and clinical characterization of Simulium neavei-transmitted onchocerciasis in western Uganda

In the forests of western Uganda onchocerciasis is transmitted by Simulium neavei s.s. Since little is known about the infection transmitted by this vector, a survey was made in 1991 with special regard to adult persons of 15 years and older in the 13 villages of the parish Kigoyera 40 km northeast of Fort Portal. 3268 (52%) of the 6271 registered inhabitants were examined clinically and parasitologically. The highest microfilaria (mf) densities were found on the buttocks, lower ones on the shoulders and the lowest on the ankles. In the parish the standardised prevalence of mf carriers was 62%. The crude prevalences of adult mf carriers ranged from 80% to 95% in the 13 villages. Densities of 100 mf/snip or more were found in 25% of male persons. The community microfilarial load (CMFL) in skin snips from the buttocks was 49 mf/snip, ranging from 22 to 93 in the 13 villages. The standardised prevalence of nodule carriers was 25% and the mean nodule load was 1.9 nodules per nodule carrier. Among 3420 nodules 90% were found on the pelvic girdle. The standardised prevalence of onchocercal dermatitis was 19%. The crude rates ranged within the age groups in males from 20% to 45% and in females from 16% to 41%. The standardised prevalence of persons presenting mf in the anterior chamber of the eye was 24% and the CMFL in the anterior chamber ranged between 1.2 and 3.3 mf/chamber in six villages. Standardised rates were 1.6% for sclerosing keratitis and 0.9% for reduced vision of 3/60 or less. These prevalences of eye lesions are comparable to those observed in West African forest areas. The CMFLs and the prevalences of mf and nodule carriers represent suitable criteria for community diagnosis of S. neavei-transmitted onchocerciasis in Uganda to guide ivermectin treatment, whereas the prevalence of "leopard skin" is not useful. Immigrants living less than five years in the endemic focus should be excluded from the assessment of mf carrier rates and those living there less than ten years from rapid assessment of nodule carrier rates.

Serological cross-reactivity between a human Ro/SS-A autoantigen (calreticulin) and the lambda Ral-1 antigen of Onchocerca volvulus

We have cloned and sequenced a 46-kD Ro/SS-A autoantigen gene that is the human homologue of the calcium-binding protein, calreticulin. The sequence of this 46-kD Ro/SS-A protein (calreticulin) has significant homology to lambda Ral-1, a recombinant cDNA clone corresponding to a major antigen of the nematode, Onchocerca volvulus, the infectious agent of onchocerciasis. We therefore sought to determine whether antibodies produced by onchocerciasis patients might crossreact with the human 46-kD Ro/SS-A autoantigen (calreticulin). 20 of 22 sera from Liberian onchocerciasis patients who had no known evidence of autoimmune disease were found to contain antibodies that reacted with the 46-kD Ro/SS-A (calreticulin) by immunoblot analysis. Characteristic of sera reactive with Ro/SS-A antigens, some onchocerciasis sera also immunoprecipitated the Ro/SS-A-associated hY RNAs. In addition, a monoclonal antibody raised against O. volvulus organisms reacted to purified human WiL-2 cell 46 kD Ro/SS-A antigen (calreticulin) by ELISA. These results strongly suggest that onchocerciasis patients produce antibodies that crossreact with the 46-kD human Ro/SS-A autoantigen (calreticulin) and raise the possibility that infectious organisms such as O. volvulus might play a triggering or exacerbating role in the human Ro/SS-A autoimmune response.

The chemotherapy of onchocerciasis. XV. Studies with albendazole

Ninety-two males, infected with Onchocerca volvulus, from an area of on-going transmission in the forest zone of southern Ghana were treated with albendazole. 31 patients received 800 mg daily x 3, 31 received 1200 mg daily x 3 and 30 others received 800 mg daily x 7. Albendazole was given as a single daily dose with a fatty breakfast. Detailed systemic, ocular and laboratory examinations were performed pretreatment and at intervals over one year. Nodules were extirpated on days 30 and 60 and examined by histopathology. All the dose regimes were well tolerated but were neither microfilaricidal nor macrofilaricidal. The main effect was embryotoxicity affecting all intra-uterine stages. The most encouraging results were obtained in the 800 mg daily x 3 group in which a prolonged suppression of skin microfilarial counts occurred. Controlled studies in combination with ivermectin are recommended to determine whether an additive effect of the two drugs would result in permanent sterilisation of the adult worms.