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Six onchocerca-nodules from five Liberian patients were examined by electron microscopy. The bulk of cells in the centre of the nodules consists of lymphocytes and macrophages. The lymphocytes can be observed in various stages of differentiation. A major part of the macrophages shows degenerative changes with decrease of lysosomes and increase of fatty vacuoles. Near the worms epithelioid cells and giant cells can be found. Other cells in the nodule include polymorphonuclear neutrophils, eosinophils, plasma cells, and mast cells. Adult Onchocerca volvulus show the basic nematode body plan. The cuticle is subdivided into cortex and two layers with differently arranged fibrillar structures. The characteristics of the hypodermal cells are best seen in the lateral chords, in the interchordal regions the hypodermis is flattened by a muscle layer. The intestine typically contains pigment granules, the cells of the epithelium have folds of their cell membranes forming a basal labyrinth. The uterus consists of two tubes in which the development of the microfilariae from the early embryonic forms to the mature stages is examined.

Most commonly used antiamoebic drugs are effective in invasive amebiasis, but their response against trophozoites of Entamoeba histolytica, present in the lumen of the human colon, is inadequate. We report the development of an antiamoebic drug carrier that may be effective against luminal infections. Our preparation consists of small silica particles (5-10 microns in diameter) covalently linked to a potent antiamoebic drug, 2-(4-aminophenoxymethyl)-5-nitro-1-methyl imidazole. Silica-drug particles were injected into mice, hamsters, and guinea pigs. We found that trophozoites phagocytosed the particles in vivo and in vitro, followed by rapid cell death due to the released drug. Analysis of mouse serum revealed that no drug was absorbed from the intestine after placement of the drug-containing particles in the intestine. The antiamoebic activity of particles recovered from the intestine was almost fully retained. This novel antiamoebic concept may be useful for luminal therapy for asymptomatic amebiasis and may minimize side effects and frequency of administration.

The micromorphology of Mycobacterium leprae is described. After fixation with osmium tetroxide supplemented with calcium ions, the cell wall was seen to be composed of three layers; the cytoplasmic membrane exhibited the architecture of an elementary membrane. The mesosomes were best visualized after fixation with glutaraldehyde; they were sometimes in contact with the nuclear equivalent. Only one sort of phosphate body was found. The nucleoid was best visualized after fixation with osmium tetroxide.

Within one year 23 patients in Lambaréné (Gabon) were diagnosed as having a Buruli ulcer (advanced cases with undermined margins). The majority of the ulcers were found in children; with the exception of one ulcer on the thorax, all ulcerations were localised at the extremities. The mode of transmission could not be clarified; extensive water tests for Mycobacterium ulcerans were negative. Observed under an electron microscope, M. ulcerans has a similar structure as other mycobacteria. Exudative inflammatory processes predominate in the ulcer floor. The small blood vessels play a considerable role in the pathological process. The mycobacteria are present in this layer, below this there is widespread necrosis of adipose tissue. The margin of the ulcer displays a granulomatous inflammatory reaction. The cytological characteristics of the mesenchymal reaction of a Buruli ulcer are described with the aid of electron microscope photographs.

A case of concurrent chloroquine and Fandisar resistance is described in a traveller returning from Gabon. Mefloquine therapy resulted in clinical cure.

Skin biopsies of 22 untreated Liberian patients suffering from onchocercal dermatitis were studied by electron microscopy. The microfilariae tend to accumulate in the upper dermis, without eliciting a cellular reaction. Occasionally macrophages or mast cells are found in the neighbourhood of the microfilariae. The most conspicuous changes concern the presence of perivascular infiltrates, comprised of lymphocytes and macrophages, with a varying admixture of plasma cells. Only exceptionally the macrophages show an increase in number and size of their lysosomes and pseudopodia as well as prominent strands of ergastoplasm indicating an activation. The endothelial walls of the dermal vessels are swollen. The amount of mast cells in the upper dermis is increased. Ultrastructural features of the microfilariae are described, especially the cuticle, muscles, central undifferentiated cells and cephalic region. When comparing these findings with the literature on the fine structural morphology of the Latinamerican form, no differences can be found.

We describe how macrophages are activated and phagocytose mycobacteria in lepromatous leprosy. The differentiation of macrophages into epithelioid cells and into giant cells in borderline leprosy is shown. Close apposition between macrophages and lymphocytes is seen in those areas where mycobacteria disintegrate inside macrophages.

The small dermal vessels play an important role for the propagation of Mycobacterium leprae. Bacteria can multiply in the endothelial cells as well as in the pericytes and can enter the blood stream from the endothelial cells and the interstitial space from the pericytes. M. leprae can be phagocytosed by blood monocytes.

The authors present their findings about a research on bacterial resistance carried out in a Lambarene hospital. Enterobacteriaceae and Pseudomonas aeruginosa present a high level of resistance to ampicillin, carbenicillin and cefalexin. About 40 to 50% of the strains appear to be resistant to chloramphenicol and trimethoprim-sulfamethizole. The most recently imported cephalosporins are effective against Gram-negative germs. Gentamycin is also effective against Enterobacteriaceae, but uneffective against Pseudomonas aeruginosa. Frequency of multi-resistance is alarming. 1/3 of the Neisseria gonorrhoeae strains are resistant to penicillin.

Cases of intestinal schistosomiasis due to S. intercalatum were compared in an area of high prevalence of S. haematobium (Palmeveas) with those in an area of low prevalence of S. haematobium (Lambaréné) in the Gabon. The patients with intestinal schistosomiasis in the area with high prevalence of S. haematobium excreted more eggs resembling S. intercalatum in the urine than those in the low S. haematobium prevalence area. It is suggested that the eggs resembling morphologically S. intercalatum might be hybrids between S. intercalatum and S. haematobium.

Skin snips of six patients with manifest onchocerciasis treated with a single dose of metrifonate (10 mg/kg) were examined by electron microscopy one, three, five and ten days after application of the drug. Compared to untreated cases 24 hours after treatment there is a marked increase in the extend of perivascular infiltrates which are composed not only of macrophages, lymphocytes and plasma cells, but also of eosinophils. Infiltrates directly around dead microfilariae are seen infrequently. This pattern of cellular reaction remains constant for the first ten days after treatment. Metrifonate obviously kills the microfilariae rapidly, already 24 hours after its application totally disintegrated parasites are to be found. On the other hand always a few intact microfilariae are seen, possibly they just hatched after treatment.

Germfree nude mice (NMRJ-nu/nu) and germfree nu/+ mice were infected with Mycobacterium marinum in the footpad test. After pretreatment with 400 mg/kg cyclophosphamide, significantly higher amounts of M. marinum were reached in the footpad and in the liver. On the other hand, the yield of M. marinum could not be elevated by in vivo inhibition of macrophages with silica.

The efficacy of oltipraz as a schistosomicidal drug was investigated in Gabonese children suffering from urinary schistosomiasis in the dosages of 1 X 25 mg/kg body weight, 1 X 35 mg/kg body weight, and 2 X 20 mg/kg body weight and compared to praziquantel, 2 X 30 mg/kg body weight. The study was undertaken in 165 patients, and follow-up investigations were carried out 6 weeks and 12 weeks after treatment. Oltipraz showed less efficacy compared to praziquantel when dosages of 1 X 25 and 1 X 35 mg/kg body weight were given. However, oltipraz 2 X 20 mg/kg body weight was equivalent to praziquantel 2 X 30 mg/kg body weight. Parasitological cure was obtained in 79% of patients treated by oltipraz and 81% of patients treated by praziquantel. Side effects were insignificant in both treatment groups. Thus, the same parasitological cure could be achieved by oltipraz as well as by praziquantel, but with a lower dosage of oltipraz.