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PubMed1999

[Relationship between the intensity of Loa loa filariasis transmission and prevalence of infections].

Filarial loiasis differs from other filariases in that most infected subjects are amicrofilaremic. This difference raises the notion of occult infection. The aim of this study was to evaluate the relationship between the intensity of transmission and incidence of infection. For this purpose we determined the incidence of loiasis both microscopically and by PCR in 201 subjects from three villages in the province of Haut Ogooue in Gabon. Intensity of transmission, expressed in ATP (annual transmission potential) in these villages was estimated to be 250 infecting larvae per individual per year (L3/man/yr) in Moyabi, 180 L3/man/yr in N'dokaye, and 43,000 L3/man/yr in Okoumbi. Although there was no significant difference between the three villages with regard to the incidence of microfilaremia (21 p. 100 and 22 p. 100), the incidence of occult infection, i.e., positive PCR in amicrofilaremic subjects, was 45 p. 100 in Moyabi, 79 p. 100 in N'dokaye and 80 p. 100 in Okoumbi. The overall incidence of loiasis was 57 p. 100 in Moyabi and 85 p. 100 in both N'dokaye and Okoumbi. These findings demonstrate that the incidence of loiasis is correlated with the intensity of transmission (p < 0.001), especially in children. Taking this information into account will improve control of Loa loa in endemic areas.

Adolescent↗
PubMedDate not supplied

[Serum filariasis due to Loa loa and Mansonella perstans in the continental area of equatorial Guinea. Preliminary results].

For the first time, a parasitologic survey has been carried out in the Niefang District (continental area of equatorial Guinea) within a sample of 829 people aged of more than 10 years. Parasitologic incidence was 27.1 p.c. for Loa-Loa and 66.3 p.c. for Mansonella perstans. Significant differences were noted in the prevalence and in the mean density of microfilariae of both species according to the altitude of the villages surveyed.

Africa, Central↗
PubMed1990

[Current possibilities in the control of Loa Loa filariasis].

Loa loa is currently considered as a major pathogen in man. The clinical repercussions of this filariasis have been clearly established and treatment is considered essential. Ivermectin, administered alone or with diethylcarbamazine presents interesting therapeutic possibilities. The review of vector control methods show that trapping is the only effective measure of protection. In order to reduce the endemicity of loaiasis, mass treatment with ivermectin could be envisaged immediately. However, the development of this filariasis is directly related to the development of the Central African forest region.

Animals↗
PubMed1989

Clinical and biological study of Loa loa filariasis in Congolese.

Clinical and biological evaluations were carried out on 84 Congolese patients with parasitologically confirmed Loa loa filariasis (without concurrent infection with other filariae) and on 98 controls without filariasis. On the patients, 72 presented with microfilaremia; another 12 with negative blood tests were seen towards the end of an episode of subconjunctival migration of the adult worm. The incidence and severity of the clinical signs depended upon the method of recruitment. The 3 most common signs were pruritus and edema (both occurring in successive acute episodes affecting mainly the hands and forearms) and subconjunctival migration of adult filariae. Papulovesicular eruptions were located mainly on the arms. Headaches and arthralgia were noted more frequently than in the controls. No relation was found between the ABO blood groups and loiasis. Eosinophilia (higher in patients with symptoms) and raised serum IgE levels were found in nearly all patients and were strongly marked in approximately 66%. A positive correlation was observed between these 2 parameters. Fluorescent antibody levels (adult filaria Dipetalonema viteae antigen) were comparatively low in patients with microfilaremia.

ABO Blood-Group System↗
PubMed1989

[The inner body of Loa loa microfilariae. Morphologic and physiopathologic data].

The innenkörper is visible in 80% of the cases of microfilariae Loa loa we have studied and stained at pH 7.2. In thick blood film, however, it was not visible. It lies between the middle of the body and the G1 = R1, cell. The central viscus rarely take the form of a single elongated mass, it most often appears moniliform with 2 to 5 granular masses and it is sometimes reduced to a few number of granulations. Its average length is 34 microns. As with W. bancrofti it would appear to have the role of a nutritional reserve.

Animals↗
PubMed1985

Activation of the alternative complement pathway in normal human serum by Loa loa and Brugia malayi infective stage larvae.

Infective stage larvae (L3) of Loa loa and Brugia malayi upon in vitro incubation with normal human serum activated the alternative complement pathway. C3 conversion products were detected on larval cuticles by eosinophil adherence and by immunofluorescence with C3c antiserum. No evidence for cuticle binding of IgG, IgA, IgM, Clq, or C4 was found by immunofluorescence. L3-induced C3 activation was inhibited by 10 mM EDTA but unaffected by 10 mM Mg++-EGTA. Human sera deficient in C2, C4, or C6 incubated with L3 resulted in C3 activation. However, sera treated with zymosan or heated for 1 h, 56 degrees C were unreactive with L3. Immunoelectrophoresis of fresh serum exposed to L3 for 1 h at 37 degrees C showed C3 cleavage products. The results indicate that these nematode L3 activate the alternative complement cascade via cuticular surface components. Larval viability was unaffected by complement activation or by adherence of eosinophils.

Animals↗
PubMed1986

Loa loa: output of microfilariae in single pair infections.

The intent of the present study was to assess the production and release of microfilariae by a single female filaria, in an in vivo system. Experimental infections of Loa loa were established in baboons by implantation of juvenile worms, typically, one female and two or three males. Infected animals were bled weekly and the number of microfilariae counted. Microfilarial counts were converted to number of microfilariae per milliliter and then the total number of microfilariae present calculated for the total volume of blood. Weekly increases in microfilarial counts were calculated for each animal. During the primary wave of microfilariae, the average weekly increase ranged from 16,000 to 194,000 (ave. 74,000). This figure gave an average daily output of 10,000 microfilariae per female. During the secondary wave of microfilariae following splenectomy, the average weekly increase ranged from 83,000 to 270,000 (ave. 157,000), giving an average daily output of 22,000 microfilariae per female. It is postulated that this level of production occurs only during the early phase of infection and is markedly reduced after the microfilaremia plateaus. The results indicate that the shedding of microfilariae by the female worm does not occur necessarily on a daily or weekly basis, and that female worms do not shed uniform numbers of microfilariae over a given period of time.

Animals↗
PubMed1984

[Localization of the filaria Loa loa in the anterior chamber of the eye. Apropos of a case].

A live and active thread-like worm was seen in the anterior chamber of a 60-year-old congolese woman. The worm was extracted and recognized as an adult female Loa loa. Taking into account the presence of nonfertile eggs in the aqueous humor and in the uterus of the filarial worm, the authors think that the maturation of the worm from a larval form takes place inside the eye. However, this localization is exceptional.

Animals↗
PubMed1995

Large scale collection of viable infective larvae of Loa loa.

A simple method to obtain large numbers of viable infective larvae (L3) of the human filarial parasite Loa loa in an endemic country is described: wild vector flies (Chrysops silacea and C. dimidiata) were caught in large numbers, sealed into pockets of mosquito netting, gently crushed on a glass plate and incubated in a funnel with medium ("Baermann technique"). 91-94% of the L3 actively left the crushed flies and accumulated in the funnel tip after 15 (80%) to 45 minutes (95%). During 111 catching days over a 12 month period, a single fly collector provided approximately 13,000 flies and 23,500 L3. The method is also considered useful for assessing loiasis-transmission, for example before and after mass treatment campaigns.

Animals↗
PubMed1998

[Release of Loa loa antigens after treatment with ivermectin].

This study concerns 112 patients of whom 104 were followed up. Microfilaricidal treatment of loaiasis is sometimes followed by severe adverse reactions. Using an immunodiffusion technique and the measure of microfilaraemia by calibrated thick smear, the authors show that the intensity of adverse reactions is proportional to the quantity of microfilariae eliminated by the treatment. The appearance of Loa loa antigens within three days following treatment was evident in 83% of the subjects. Five patients presenting the serious adverse reactions described belonged to this group. However, the precise cause of these adverse reactions, allergic or toxic, has not been demonstrated.

Animals↗
PubMedDate not supplied

[Screening of microfilariasis in blood (Loa Loa) among the immigrant population in endemic areas].

BACKGROUND: Given the increasing flux of immigrant population from high-risk areas to our country, the need of screening for loasis arises, despite systematic screening being a debated and poorly evaluated practice to which there is no protocol. This study is aimed at identifying the population to which loasis screening would be most appropriate, by drawing a comparison among four alternatives. METHODS: Case and control group study, involving 30 cases (all those who came to our unit for treatment and who tested positive for Loa Loa in a microfilariae in the blood detection test) and 90 control cases (three controls per case from among the subjects having tested negative for microfiliariae in the blood chosen at random without any pairing criteria). RESULTS: Of the 1,638 subjects on whom the microfilariae blood test was performed, 30 tested positive (1.8%; 1.2-2.6%). Of these 30 cases of loasis, 76.7% (23; 57.7-90.1%) had eosinophilia (OR 8.8; 3.3-23.1; p<0.0001) and 30.0% (9; 14.7-49.4%) compatible clinical symptoms (OR 2.8; 1.0-7.5; p=0.04). If we were to apply the screening test to the entire immigrant population coming from endemic areas, we would have to perform 54.6 tests to detect one case. If we were to perform the test on patients showing eosinophilia and/or compatible clinical symptoms, we would have to perform a smaller number of tests for every case detected (NNS=29; IC=21-48), but there would be 16.7% (5; 5.7-34.7%) false negatives. CONCLUSIONS: Conducting a screening test with determination of microfiliariae in the blood on the immigrant population coming from Central and West Africa, independently of the presence of eosinophilia or compatible clinical symptoms, would be indicated, provided that the necessary resources are available.

Adult↗
PubMed1990

Calcifications of the breast probably due to Loa loa.

Five cases of calcification of the breast due to filariasis in Congolese women are reported. The cases were discovered during mammographies carried out for suspect carcinoma (4 cases) and benign tumor (1 case). The geographic origin of the patients, a past history of subconjunctival filarial migration in 2 individuals, the bilateral localization, and, above all, the radiographic appearance and size of the calcifications, suggested that the images were due to Loa loa.

Adult↗
PubMed1995

Longitudinal survey of Loa loa filariasis in southern Cameroon: long-term stability and factors influencing individual microfilarial status.

A longitudinal, one-year survey of Loa loa infection was carried out in an endemic area of southern Cameroon. Parasitologic samplings (calibrated thick blood smears) were performed every two months to study the evolution of loiasis infection at both the population and the individual level. The mean number of measurements by subject was 3.8 (range 1-6). At the population level, prevalence of infection and microfilarial load were found to be very stable over time. This observation is consistent with the existence of an important reserve of parasitic material available for vectors and the maintenance of high levels of transmission. At the individual level, both the microfilarial status (microfilaremic/nonmicrofilaremic) and the level of parasitemia showed a remarkable stability over time. Age was the relevant factor that influenced the individual microfilarial status in the whole population. When only microfilaremic individuals were taken into account, age did not influence the level of microfilaremia, suggesting that loiasis could be considered as a noncumulative disease. The stability of individual microfilarial status and the pattern of infection variations observed with age support the view that genetic factors might be involved in host defense mechanisms against loiasis infection.

Adolescent↗
PubMed1984

Loa loa: ocular filariasis in an African student in Missouri.

Ocular filariasis was observed in an African student living in Missouri. The adult female Loa loa worm was seen migrating under the conjunctiva. There was 34% eosinophilia and a high microfilaremia. The patient was successfully treated with diethylcarbamazine (Hetrazan) with no appearance of allergic manifestations.

Adult↗
PubMed1997

[Nephropathy and filariasis from Loa loa. Apropos of 1 case of adverse reaction to a dose of ivermectin].

A patient with a filarial infection due to Loa loa, received single oral dose of ivermectin A few hours after, he has presented a severe renal impairment. Native of the Cameroons, he was also treated for malaria. A renal biopsy has been done, because of chronic proteinuria. It has showed microfilariae in glomeruli, thickening of the basement membrane and a segmental and focal mesangial hyalinosis. By immunofluorescence microscopy there were granular deposits of IgM and C3 along this membrane. Electron microscopy has showed subepithelial electron- dense deposits. This suggests that the renal disease is immunologically induced. During the therapy, adverse reactions seemed to be related with massive liberation of filarial antigens. This is well known with diethylcarbamazine but also now, sometimes with ivermectin.

Adult↗
PubMed1977

Localization of acid phosphatase in microfilariae of Loa loa and Dipetalonema perstans from Cameroun.

The histochemical pattern of acid phosphatase activity in the microfilaria of L. loa showed a diffuse red staining all over the body, with conspicuous staining of the excretory and anal vesicles, Innenkörper, amphids and phasmids. In D. perstans, the enzymatic activity was localized chiefly in four regions corresponding to the excretory and anal vesicles, amphids and phasmids of the microfilariae. A considerable loss of enzyme activity was observed in microfilariae that had been stored in a refrigerator for somedays prior to their fixation.

Acid Phosphatase↗