Annales de parasitologie humaine et comparee最新文献

A study of the anatomo-pathological lesions induced by Monanema martini, a filaria with skin-dwelling microfilariae, was performed using 65 Lemniscomys striatus fixed from 30 minutes to 36 months after inoculation of the infective larvae, 5 Arvicanthis niloticus and 3 Meriones unguiculatus fixed during the patent phase, and controls. Attempts at quantification of lesions in L. striatus was made. Approximately 20% of L. striatus had microfilariae in the eyeballs, and many more presented ocular lesions. The delay of the patent period seems to have more effects on the gravity of lesions than repeated inoculations. The location of the lesions and parasites presuppose that microfilariae enter the eyeball through the lymphatic capillaries of the irido-corneal angles. Cutaneous lesions were often severe: there is a parallel between the importance of lesions and the abundance of microfilariae. Larvae are responsible for damage to various structures of the lymphatic system (thrombo-lymphangitis, acute or granulomatous lymphadenitis...) into which they migrate, explaining the mechanism of elephantiasis. These rodent lesions appear similar to those observed in human onchocerciasis and lymphatic filariasis. Whatever the M. martini stage and the organ examined, major lesions belonged to the inflammatory process. Various types of inflammatory reaction (acute, subacute, or chronic inflammation, scarring sclerosis etc.) can co-exist within a single tissue area. The accidental escape of a microfilaria from a lymphatic capillary into the connective tissue (including the corneal stroma) induces an inflammatory reaction. Thus M. martini, as human Onchocerca species, causes a chronic disease, associating recent lesions to old ones.

Since 1971, at the Laboratory of Parasitology, Faculty of Veterinary Medicine, University of Bologna, 30 cases of human dirofilariasis were observed out of the 101 cases reported in Italy. The causative agent was identified in nearly all the cases as Dirofilaria repens (Nematoda, Filarioidea) a parasite relatively common in the dog in Italy. 23 cases were localized in the subcutaneous tissue, 4 in the submucosa and 3 in the lungs. In the majority of the cases the diagnosis had been misinterpreted, the lesions being first seen as malignant or benign tumours or foreign-body granuloma. The parasite was histologically recognized. In 3 cases the parasite could be extracted intact from the nodule. The authors believe that human dirofilariasis is more frequent than reported by the relevant scientific literature in that many cases are likely to recover spontaneously while others would remain undetected.

The glossina control turns towards cheaper, ecological, easier techniques: trapping, which the efficacy might be increased by odour attractants; synthetic pyrethrinoids (impregnated targets; dipping or application of "Pour-on" formulations on skin of cattle). Only one new trypanocide was set up during the last 25 years: Melarsamine, arsenical derivative, effective in camels, cattle, horses infected by Trypanozoon (3.5 mg/kg b. w. by IM or SC routes). The trypanotolerant cattle is characterized by a better control of parasitemia and anaemia, dominant gene A of hemoglobin and gene F of albumin, a better immune response and a smaller drop of hematocrit. Monoclonal antibodies are used to detect, in micro-ELISA plates, circulating somatic trypanosomal antigens of T. brucei (s. l.) and T. evansi (common antigens), T. congolense and T. vivax (species specific antigens).

The emergence of new parasitic diseases has encouraged studies on the elucidation of the mode of action of new and old antiparasitic drugs, and has led to the development of new chemical series. Resistance occurs rapidly when a single drug is used massively in human and animals. A better knowledge of the mode of action allow synergistic combination of compounds, slow-release devices proposed for cattle. Another alternative is to improve bioavailability of antiparasitic drugs by targetting at the parasite molecular level with prodrugs, drug-carriers as liposomes, nanoparticles. The use of new compounds should be expected with relative optimism.

An illustrated description of the Pseudhymenolepis turkestanica sp. n., a new cestode from piebald shrew (Diplomesodon pulchellum) from Middle Asia is given. P. turkestanica differs from the most similar species P. papillosa Hunkeler, 1970 by the measures of the scolex and rostellum, the number of rostellar hooks and the size of embryonic hooks. P. turkestanica is considered as a specific parasite of D. pulchellum.

This workshop draws attention to an increasing body of evidence which supports the view that parasites of aquatic animals are influenced by pollution. Pollutants might promote increased parasitism by impairing the host's immune response or favouring survival and reproduction of intermediate hosts. Decreased parasitism might occur because of toxicity to free-living stages, intermediate hosts or alteration of the host's physiology. Prevalence and intensity of ectoparasites in conjunction with histopathology and concentration of xenobiotics in both fish and parasites appear to be a promising approach. Future research on the interaction of pollution on parasites of animals should focus on a combination of field and laboratory studies, especially exposing fish in cages to polluted water.

The Round Table addressed 4 main themes: 1. An overview (E. JAMES), summarising cryoprotectants and cooling procedures; 2. Cryobanks and genetic diversity (R. MULLER) with a list of parasite cryobanks; 3. New techniques in cryopreservation including those for Cryptosporidium (P. ROSSI), metacestodes of Echinococcus multilocularis (J. ECKERT), entomopathogenic nematodes (I. POPIEL) and Trichinella (P. ROSSI); 4. Large scale cryopreservation methods for use in vaccines (E. JAMES) and for industry (I. POPIEL).

The development of Leishmania spp. in their vectors is a complex process involving behavioural, morphological and biochemical changes. The process differs between Leishmania species. Recent information on the developmental process and its regulation, summarised in this report, relates to possible separation of amastigotes into two separate developmental lines, development of infective forms of promastigote, attachment of certain, possibly altruistic promastigotes to the gut wall, and the possibility of genetic exchange.

Round table on toxoplasma and toxoplasmosis touch on treatment, pathogeny and involvement in biological diagnosis, antigenic structure and cellular immunity. The research of new toxoplasmicide molecules and that of pharmacological experimental models remain difficult. On the contrary, there is a large development in the parasitological diagnosis with PCR and in the immunological diagnosis with more targeted antigens produced by genetic engineering or by biochemical purification. A better knowledge of this antigenic structure will also enable to select protective molecules for vaccinations. This goal will be reached when our knowledge will be completed on the cellular immunity during toxoplasmosis.