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

In an attempt to establish the diarrhoeogenic potential of the newly identified Artyfechinostomum oraoni, which was associated with human diarrhoea in a tribal community near Calcutta, India, two naturally infected domestic pigs of the locality were followed in captivity. Both pigs developed fatal diarrhoea after 5 months. The autopsy revealed a massive infection with the echinostome on a haemorrhagic and oedematous mucosa of the jejunum and duodenum extending up to pyloric end of the stomach. It is suggested that similar pathology might also be operating in the infected man.

Diagnosis of fasciolosis in the acute phase depends on a sensitive and accurate serological test. The present study is an evaluation of the efficacy of excretory-secretory Fasciola gigantica adult worm antigen by IgM ELISA. Thirty eight patients with acute fasciolosis and 14 in the chronic phase together with 23 patients with different parasitic infections were introduced in the study. Seventeen healthy, parasite free individuals, were served as controls. A crude excretory-secretory antigen and its fractions I and II (obtained by gel filtration chromatography on Sephadex G-200) were tested. The crude antigen revealed 100% sensitivity, 94% specificity and 98% accuracy at the cut off level of 0.3 in acute infection. It gave positive results in 77% of chronic cases. Cross reactions with Schistosoma and Toxoplasma were negligible. A significant positive correlation between IHA titres and ELISA O.D. readings was observed. Fractions I and II proved of no diagnostic significance. The test system F. gigantica E/S product by IgM ELISA is highly recommended for diagnosis of acute fasciolosis.

In order to isolate proteinase genes from parasitic nematodes by polymerase chain reaction (PCR) techniques, we employed a pair of consensus oligonucleotide primers designed to anneal to the active site cysteine (primer ncpC) and asparagine (primer ncpN) coding regions of cysteine proteinases. The primers were biased toward the nucleotide and codon usages of cysteine proteinase genes of nematodes and were based on the consensus nucleotide sequences flanking the active site residues of genes from Haemonchus contortus, Caenorhabditis elegans, and Ostertagia ostertagi. We employed 'touchdown' PCR conditions and were able to amplify novel cysteine proteinase gene fragments from the rodent parasite Strongyloides ratti, the human pathogen S. stercoralis, the canine hookworm Ancylostoma caninum, and from C. elegans. These clones are gene homologs of cathepsin B-like (lysosomal associated) proteases and will facilitate screening of both cDNA and genomic DNA libraries.

Ivermectin is the drug of choice for the treatment of onchocerciasis. However at the recommended dose of 150 micrograms/kg, it neither kills nor permanently sterilises the adult worms. We investigated whether high doses given with and without a preceding 150 micrograms/kg 'clearing' dose would be tolerable as well as effective against the adult worms. Seventy-five healthy males with moderate to heavy infections with Onchocerca volvulus were enrolled in a double-blind trial to receive one of the following treatment regimens: 150 micrograms/kg followed by placebo (9 patients); 400 micrograms/kg with (9 patients) or without (16 patients) a clearing dose; 600 micrograms/kg with (8 patients) or without (16 patients) a clearing dose and 800 micrograms/kg with (8 patients) or without (9 patients) a clearing dose. Detailed examinations were conducted before and at various times after treatment. A preliminary report on the clinical and laboratory safety as at 30 days is presented. All the regimens were well tolerated. No clinical or laboratory drug related effects were observed. The overall severity of the Mazzotti reaction was similar in all groups. Ocular reactions were minimal and there were no changes in ocular function or in fluorescein angiograms. The groups were similar in the extent of microfilaricidal activity; there was however a suggestion that microfilariae were killed more rapidly at 400 micrograms/kg and 600 micrograms/kg but not at 800 micrograms/kg. This needs further study. Single doses of ivermectin up to 800 micrograms/kg are well tolerated; no special precautions for treatment monitoring are required and a 'clearing' dose is not necessary.

The validity of recently much argued phenomenon of facilitation in the transmission of filariasis was considered by examining previously published papers. It was concluded that there was no clear evidence to support the existence of facilitation and facilitation-based unstable equilibrium in relation to microfilaria prevalence and density in human population below which filariasis would spontaneously disappear, even when the vector was Anopheles mosquitoes. Instead, the existence of a critical level of man/mosquito contacts for the disappearance of filariasis was suggested.

A survey for the prevalence, geographical distribution and clinical manifestations of onchocerciasis was conducted on the Island of Bioko (formerly Fernando Póo), Equatorial Guinea, between 1987-89. The whole population (1799 inhabitants) of thirteen villages distributed around the island was surveyed. Identification data, physical examination and Snellen "E" test for visual acuity were performed. Skin snips were taken from both iliac crests and right scapula and calf. Differential diagnosis between Onchocerca volvulus and Mansonella streptocerca was carried out in both fresh and Giemsa stained preparations. The overall prevalence (+ skin snips) and mean microfilarial density were 75.2% (range 51.9% to 87.1%) and 32.2 mf/snip respectively. Skin snips showed a higher microfilarial density from iliac crests. The following clinical manifestations were found: 560 (31.2%) with nodules; 518 (28.8%) with dermatitis, pigmentation changes and cutaneous atrophy; 753 (41.9%) with lymphoadenopathy and lymphoedema. Blindness due to different causes was registered in 13 cases (0.8%). The results showed that onchocerciasis is hyperendemic and widespread over the island. It is estimated that almost the whole population (62,000) is at risk of infection.

48 newly synthesized acridine derivatives of different classes were screened for antitrypanosomal activity. They showed a dose dependent effect on Trypanosoma rhodesiense and T. brucei bloodstream forms measured by the inhibition of esterase activity in a fluorescence based in vitro assay. After analysis of the IC50 and MIC values of the investigated acridines it was obvious that no new compound reached the level of the trypanocidal drugs in use (50 ng/ml). Most of the derivatives had IC50 values in the range of 1 to 10 micrograms/ml. 9 derivatives from different classes of acridines were in vitro active below 1 microgram/ml. Correlations between structure and effect on trypanosomes have been elucidated by comparing the IC50 and MIC values of these compounds, in the course of which no significant differences in the drug susceptibility between T. brucei und T. rhodesiense was noticed. The dialkylaminoalkyl derivatives among the group of the 9-thioacridines were slightly more potent than the mono-alkylated ones. 1,2,3,4-tetrahydro-9-thioacridines showed the influence of higher substituted side chains on the trypanocidal activity in the same way as 9-thioacridines. The corresponding ketones of 9-thioacridines confirmed the tendency of increasing toxicity due to the derivatisation of the dialkylaminoalkyl side chain. Within the series of the 9-aminoacridines the elongation of the side chain did not markedly change the activity, however the IC50 values are generally low between 0.13 and 1.2 micrograms/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

A 43 year old man with falciparum malaria acquired in East Africa was treated with quinine intravenously at a loading dose of 500 mg and subsequently 500 mg tid. Within 42 hours after initiation of treatment the parasitaemia increased from 2% to 16%. A RIII-resistance against quinine was suspected and therapy was switched to oral administration of halofantrine (500 mg at 6 hourly intervals) which led to complete recovery. Blood samples were cultured for malaria parasites 42 hours after start of therapy with quinine but before initiation of therapy with halofantrine. In vitro resistance testing was performed with samples directly derived from the patient and after 24 and 48 hours of culturing. In repeated tests an in vitro resistance to quinine could be confirmed (IC50: 25.6 x 10(-6) mol/l, IC99: > 51.2 x 10(-6) mol/l) while the strain was fully susceptible to chloroquine (IC50: < 0.4 x 10(-6) mol/l, IC99: 1.6 x 10(-6) mol/l), mefloquine (IC50: < 0.4 x 10(-6) mol/l, IC99: 3.2 x 10(-6) mol/l), tetracycline (IC50: 0.16 x 10(-6) mol/l, IC99: 0.32 x 10(-6) mol/l) and halofantrine (IC50: 0.02 x 10(-6) mol/l, IC99: 0.04 x 10(-6) mol/l). Increased susceptibility to quinine after addition of verapamil was noted. The presence of a specific mutation, on the pfmdr1-gene on chromosome 5, previously associated with chloroquine drug resistance, could be confirmed by polymerase chain reaction. To our knowledge a R III-in vivo and in vitro resistance of Plasmodium falciparum to quinine has not been described yet in East Africa.(ABSTRACT TRUNCATED AT 250 WORDS)

Analyses of the health costs in developing countries have mainly dealt with provider costs. This is in spite of the fact that the bulk of illness related costs is borne by households. Where studied, household time and financial costs have not been treated in a comprehensive way. However, an incomplete cost assessment will lead to an underestimation of household costs. Using data from a household interview survey in a rural area of Burkina Faso, the authors carried out an exhaustive assessment of the economic cost of illness that households incur. Financial costs included out-of-pocket expenditures for drugs, fees, transport to the treatment site, lodging and food for accompanying household members. Time costs, in turn, were comprised of production foregone both by the sick person and by healthy household members, who tended to the sick. Time costs amounted to by far the largest proportion (73%) of total household costs. Of the total amount of illness related time loss of the average household, 45% was due to the fact that healthy household members tended to or accompanied their sick kin. Of the financial cost items, expenditures for drugs or traditional products represented 62%. When Western type services were sought, expenditures for transport, food etc., exceeded those for treatment fees. Total cost of illness was 4,002 F CFA/month for the average household. This amounted to 3.7% of household income and to 6.2% of household expenditures in the reference month. The authors discuss policy measures aimed to reduce household time costs.(ABSTRACT TRUNCATED AT 250 WORDS)

CGI 18041, an adduct of benzothiazol isothiocyanate N-methyl piperazine, was evaluated for its antifilarial properties in subperiodic Brugia malayi infected Presbytis cristata. Animals experimentally infected with 200-400 subperiodic Brugia malayi infective larvae, were matched according to microfilaria density, infective dose, and duration of infection. They were then randomly assigned to various treatment and control groups. The compound was suspended in 1% Tween 20 in distilled water, sonicated, and then fed to monkeys using a stomach tube. Control animals received an equivalent volume of drug diluent. CGI 18041 at a single oral dose of 50 mg/kg had complete adulticidal and microfilaricidal activities against subperiodic B. malayi in P. cristata. It was also extremely effective at a single dose of 25 mg/kg, the final geometric mean microfilaria count being 1.6% of initial level, and only 1.0% of the infective dose was recovered as live adult worms at autopsy 6 weeks post-treatment. In control animals, these were 226.9% and 5.56% respectively.