Tropical medicine and parasitology : official organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ)最新文献

Time series of the numbers of Simulium damnosum s.l. caught biting man each day at various locations in West Africa were investigated using auto-correlation methods and spectral analysis. After differencing the data sets up to the number of times for which significant partial autocorrelations were detected, significant peaks were found in the periodograms of the transformed series in 22 of the 23 series examined. The major peaks revealed the existence of cycles with periodicities of 2 to 3 days, which were interpreted as being indicative of gonotrophic cycle lengths. There was inconclusive evidence suggesting that the cycles for S. squamosum were slightly longer than those for S. damnosum s.str. and or S. sirbanum. One data set with associated parous rates was used to estimate a survival probability per oviposition cycle for S. damnosum/S. sirbanum of 0.46.

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.

Biological reactions caused by free radicals at the molecular and cellular levels engage many different biochemical components which can be directly damaged by the oxidizing radicals and which eventually promote pathological processes. Defence mechanisms have evolved to limit the speed of production of free radical damage; they include low molecular antioxidants and antioxidant enzymes. In this study, the activity of peroxidase acting against peroxides appearing in muscle of mice at different stages of infection with Trichinella spiralis was analyzed. The presented results are part of a bigger research concerning the defence mechanisms of the host in the course of experimental trichinellosis.

At the Centre International de Recherches Médicales (CIRMF) in Franceville, Gabon, a mini-symposium was held on the progress made in the research and control of loiasis from 20-22 February, 1995. The mini-symposium fulfilled its role as a platform for summarising and discussing recent advances in the research of this filarial infection and enabled the formulation of the presently most challenging issues: a specific and sensitive diagnostic test, the potential of ivermectin as a mass treatment and the factors and mechanisms of occult loiasis.

In contrast to human carriers of microfilariae, filariae infected rodents generally tolerate an effective microfilaricidal treatment without obvious signs of adverse reactions. The study shows, however, that also the filariae (Litomosoides carinii, Brugia malayi) infected rodent Mastomys coucha can be rendered sensitive to side effects of the treatment by the administration of D-galactosamine (D-Gal), due to reduction of liver UTP levels. Independent of the drug (diethylcarbamazine, ivermectin, CGP 20376) and the parasite species, D-Gal-primed infected animals died within 4 days after a microfilaricidal treatment. Lethal effects did also occur in naive animals to which microfilariae had been transfused 18 h prior to the challenge with D-Gal and a microfilaricidal, provided the animals had received at least approximately 10(3) larvae/g body weight. Both infected animals and naive recipients of microfilariae could be protected from death by cyclosporin A, polyclonal antibodies to mouse TNF or suitable amounts of NG-monomethyl-L-arginine. Pentoxifylline was less protective. The results suggest that components play a role in adverse reactions after microfilaricidal treatment, which are released by dying/dead microfilariae and may interact with T lymphocytes independent of a specific state of immunity. In a sequela, TNF released by T cells seems to induce an excess synthesis of N-oxides which appear to be the final morbific agent.

The sensitivity and the specificity of the antigen detection ELISA proposed by Nantulya and Lindqvist (1989) for the diagnosis of African Animal Trypanosomiasis have been assessed in naturally-occurring infections. 1633 cattle were sampled in trypanosomiasis endemic area and examined for trypanosomes by darkground/phase contrast buffy-coat method described by Murray et al. (1977) and for circulating antigen by ELISA. Fifty sera from Markoye, a tsetse free area in north of Burkina Faso, and 49 sera from Germany were also tested. In trypanosomiasis infested area, BCT detected 144 (8.8%) positive animals while Ag-ELISA revealed 65.8% of positive. Out of the 144 BCT-parasite-positive, Ag-ELISA enable to detect 75% of positive. The predominant trypanosomes identified by BCT was Trypanosoma vivax followed by T. congolense while Ag-ELISA indicated T. congolense followed by T. brucei. Ag-ELISA detected 76.5% out of the 51 T. congolense-BCT-positive and only 17% of all T. vivax BCT-positive. Cattle carring mixed infection involving two or three trypanosomes, particularly those with T. brucei and T. congolense are the most frequent. In tsetse free area, Ag-ELISA detected one positive cattle carring T. brucei and T. congolense and showed an apparent specificity of 98%. No serum from Germany was detected positive. This study suggests the joint use of Ag-ELISA and BCT for the diagnosis of trypanosomiasis particularly in epidemiological study in endemic area.

Onchocerca ochengi, a bovine parasite, is a suitable model for research on human River Blindness. However, the microfilariae are normally found concomitantly with at least one of the other three bovine Onchocerca species O. dukei, O. gutturosa and O. armillata causing difficulties for the work on the microfilariae. We describe a simple and field applicable method for the separation of living O. ochengi microfilariae from the other Onchocerca species using Sephadex G-25 columns. Elution of mixed populations resulted in the passage of O. gutturosa and/or O. dukei in the initial 1 ml fraction with O. ochengi eluting as an almost 100% pure species in the 4th and 5th fractions.

Unlabelled: 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.

Two enzyme immuno assays based on a single recombinant Entamoeba histolytica antigen (P1-EIA) or soluble E. histolytica extract (SA-EIA) as well as a latex agglutination test using an E. histolytica membrane fraction (M-LA) were evaluated for its use to detect anti-amebic serum antibodies in patients from Durban, South Africa, an area endemic for amebiasis. In a previous study, all three test systems were found to be reliable in terms of sensitivity and specificity when applied to sera of European individuals. By analysing a total of 167 serum samples of patients from the Durban area, suffering from invasive amebiasis (n = 76) or miscellaneous diseases unrelated to E. histolytica infection (n = 91), the present study revealed sensitivity for the detection of anti-amebic antibodies of 97.4% for SA-EIA, 86.8% for P1-EIA and 96.1% for M-LA, respectively. Specificity was high for P1-EIA (96.7%) and M-LA (92.3%) but substantially lower for SA-EIA (62.6%). In addition, antibody responses to the recombinant P1 antigen were analysed in 16 patients with amebic liver abscess before and after anti-amebic treatment. The results indicated that most of the patients lost their specific antibody response within 7 month of follow up. Therefore, P1-EIA seems to be a valuable test for distinguishing between present and past E. histolytica infections.

1,500-2,000 head of cattle were treated with deltamethrin 1% Spot On in an area of high tsetse densities, notably of Glossina morsitans submorsitans. After four treatments at monthly intervals, the time between two treatments was increased to two months. 11 months after the commencement of the campaign the fly population had decreased from initially 54.2 flies/trap/day to densities varying between 0.06-2.0 flies/trap/day, mostly G. palpalis gambiensis. Blood-meal analysis showed that this species was surviving in limited areas, mainly feeding on monitor lizards; consequently it is unlikely that this species can be eradicated solely by the use of cattle treated with a pyrethroid. The resistance of Trypanosoma congolense to all commercially available trypanocides necessitated the epidemiological monitoring of calves which were born after the start of the campaign in order to reasses the real challenge. The risk of new infections was low, basically due to contracts between the cattle and tsetse outside the ranching area. A weight increase from 122.3 kg to 213.6 kg of calves aged 6-12 months was recorded from October 1993 to October 1994. An average daily weight gain of more than 400 g was observed from the end of April 1994 to the beginning of August 1994.