Amphizoic small amoebic protozoa are capable of existing both in 'free-living' and in 'parasitic' form depending on the actual conditions. Two genera (Naegleria and Acanthamoeba) have become recognised as opportunist human parasites. Since the first description in 1965 of a lethal case of primary amoebic meningoencephalitis (PAM) caused by Naegleria, many more (mostly lethal) cases have been reported, while granulomatous amoebic encephalitis (GAE), as well as eye (keratinitis, conjunctivitis, etc.), ear, nose, skin and internal organ infections caused by Acanthamoeba have also occurred in rapidly increasing numbers. Both pathogenic and non-pathogenic species of Naegleria and Acanthamoeba are found worldwide in water, soil and dust, where they provide a potential source of infection. Successful differential diagnosis and appropriate (specific) therapy depends on precise laboratory identification of the 'free-living' amoebae. In most cases, isolation from the environment can be achieved, but identification and differentiation of the pathogenic and non-pathogenic strains is not easy. The methods presently available do not fulfil completely the requirements for specificity, sensitivity and reliability. Morphological criteria are inadequate, while thermophilic character, pH dependency and even virulence in infected mice, are not unambiguous features of pathogenicity of the different strains. More promising are molecular methods, such as restriction endonuclease digestion of whole-cell DNA or mitochondria1 DNA, as well as iso-enzyme profile analysis after iso-electric focusing and staining for acid phosphatase and propionyl esterase activity. Use of appropriate monoclonal antibodies has also yielded promising results in the differentiation of human pathogenic and non-pathogenic strains. However, quicker, simpler, more specific and reliable methods are still highly desirable. The significance of endosymbiosis (especially with Legionella strains) is not well understood. The results of a systematic survey in Hungary for the isolation and identification of 'free-living' amoebae, including an investigation of the Hungarian amoebic fauna, the isolation of possibly pathogenic Naegleria strains and of some Acanthamoeba strains from eye diseases, as well as the finding of a case of endosymbiosis, are also reported here.

Most of the above cases of dirofilariosis are certainly autochthonous infections. The increasing number of diagnosed cases suggests that this zoonosis is becoming more important in central Europe and that the incidence may increase with the improvement of clinical diagnosis.

Toxocara infection is associated with an increased prevalence of airway symptoms and may be a possible aetiologic agent of chronic cough. The occurrence of toxocariasis in Hungary is mild and/or sporadic. The purpose of this study was to investigate the levels of serum cytokines (IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IFN-gamma and TNF-alpha) and total IgE, the blood eosinophil count, the results of skin prick and non-specific bronchus provocation tests in Toxocara-seropositive children with chronic cough relative to those in healthy controls. The patients exhibited moderate eosinophilia, significantly elevated levels of serum total IgE, IL-6, IL-10, IL-13 and IFN-gamma, and higher skin reactivity to common allergens, whereas the bronchial hyperreactivity was similar in the two groups. The protective proinflammatory cytokines (IL-6, IFN-gamma and IL-13) in association with the anti-inflammatory cytokine (IL-10) were simultaneously increased in Toxocara-infected children with chronic cough. During infections, the activation and suppression of immune processes occur simultaneously and cytokines of Th1/Th2 and regulatory T cells contribute to the regulation of the immune response evoked by helminth infections (depending on the parasite load, the timing and duration of the infection and the status of the host immune system).

In the genus Giardia (G.) intestinalis is the only species found in humans as well as in other mammals, including domestic and farm animals. Molecular characterisation of strains isolated from different hosts revealed the existence of seven major genotypic assemblages. Assemblage A and B isolates have been recovered from a broad range of hosts, including humans, livestock, cats, dogs, beavers and guinea pigs. Infection and subsequent cyst shedding contaminates the environment for all mammals, including humans. In this preliminary investigation we studied the prevalence of Giardia infection in kennel dogs from Hungary by microscopic examinations and using a G. intestinalis Agspecific coproantigen test. In order to investigate the genotypes of Giardia, a nested PCR specific for Giardia 18S-rDNA was introduced. All sequenced samples displayed the sequences described for Assemblage D and C dog-specific G. intestinalis strains. These results indicate, however, that dog giardiosis is highly prevalent in the studied geographical areas, but it doesn't present severe zoonotic potential. In the course of the study, the higher sensitivity of the coproantigen test compared to microscopy, and the significant decline in the infection rate with the increasing age of the dogs sampled was clearly pointed.

Antenatal, early diagnosis and treatment of toxoplasmosis in mothers, together with treatment and follow-up of their offspring, may considerably reduce the incidence of the disease in the offspring.