Hanns M. Seitz

Structured treatment interruption in patients with alveolar echinococcosis

In human alveolar echinococcosis (AE), benzimidazoles are given throughout life because they are only parasitostatic. It has been a longstanding goal to limit treatment, and recent reports suggest that, in selected cases, benzimidazoles may be parasitocidal. Previously, we showed that positron –emission tomography (PET) using [18F]fluoro‐deoxyglucose discriminates active from inactive lesions in AE. We have now performed a 3‐year prospective study in 23 patients and conducted a structured treatment interruption in those without signs of PET activity. Disease progression was further assessed by ultrasound, computerized tomography, laboratory parameters, and clinical examination.We found PET‐negative lesions in 15 of 23 patients and benzimidazoles were discontinued in these patients. After 18 months, patients were reevaluated, and, of the 15 initially PET‐negative patients, 8 showed either new activity on PET (n = 6) or signs of clinical progression (n = 2). Reinitiation of benzimidazoles halted parasite growth again. No further progression was detected after 36 months. PET had a sensitivity of 91% for the detection of active lesions. In conclusion, despite successful suppression of metabolic activity, in most cases benzimidazoles do not kill the parasite. PET is a reliable tool for assessing metabolic activity and for timely detection of relapses. Neither duration of treatment, kind of treatment, lesion size, calcifications, or regressive changes reliably indicate parasite death. We discourage the discontinuation of benzimidazoles in inoperable AE even after many years of treatment. However, patients with a poor compliance of benzimidazole intake or patients suffering from side effects to benzimidazoles might be assessed for PET negativity. If permanent discontinuation of benzimidazoles is attempted, the course of disease should be followed by PET. (HEPATOLOGY 2004;39:509–517.)

Extrahepatic Alveolar Echinococcosis without Liver Involvement: a Rare Manifestation

SummaryBackground: Alveolar echinococcosis (AE) primarily affects the liver and extrahepatic disease is considered the consequence of a secondary infection via metastatic spread from the hepatic focus. Patients: Two patients with extrahepatic AE without liver involvement are presented. The first case is a patient with AE of the spleen and a small pulmonary calcification. In the second case exclusive affection of the spine was observed. Discussion: Various pathogenetic explanations for hepatic omission appear plausible: a passage of oncospheres through hepatic sinuses without causing disease, a passage via lymphatic vessels or via portocaval anastomoses and the vascular passage in a retrograde fashion. Extrahepatic manifestation of AE without apparent liver involvement is rare. However, AE should be taken into account among other differential diagnoses even in cases of extrahepatic lesions without liver involvement.

Individual cases of autochthonous malaria in Evros Province, northern Greece: serological aspects.

Abstract. Prompted by four autochthonous cases of malaria in 1994 and 1995 in Evros Province, northern Greece, we conducted an entomological study between 1997 and 1999 in Nipsa and Chandras, rural locations where two of the four cases had occurred, and in Feres where two additional autochthonous malaria cases had been diagnosed in 1998. In Nipsa and Chandras, we identified 29 Anopheles breeding sites and characterized them by physicochemical parameters. Larvae were collected both at these sites and in a brackish water breeding site near Feres in the Evros River delta. Adults were caught in sheds at all three locations. Morphology was used to classify larvae and adults as A. superpictus or as species belonging to the A. claviger or A. maculipennis species complexes. The latter were further identified by PCR as being A. maculipennis s.s., A. melanoon and A. sacharovi. Of the A.maculipennis complex larvae collected inland, approximately 94% were A. maculipennis s.s. and 6% A. melanoon, whereas all larvae collected in the coastal region were A. sacharovi. In contrast, the A.maculipennis adults were A. maculipennis s.s. and A. melanoon (both 47%), and A. sacharovi (6%). In the coastal region, no A. maculipennis s.s. adults were caught. The ratio of A. melanoon adults collected to A. sacharovi was about 3:1. As shown by a bloodmeal ELISA, only 5 of 266 fed females (1.9%) had ingested human blood, whereas 232 (87%) had fed on goats. Of the mosquitoes containing human blood, two were A. melanoon, one A. sacharovi and one A. maculipennis s.s. One human blood specimen could no longer be assigned to a particular mosquito.

Substantial rise in the prevalence of Lyme borreliosis spirochetes in a region of western Germany over a 10-year period.

ABSTRACT More than a decade after a study on the transmission cycle of Borrelia burgdorferi sensu lato in the Siebengebirge, a nature reserve near Bonn, Germany, questing nymphal and adult Ixodes ricinus ticks were collected again in three selected areas of the same low mountain range and examined for infection with B. burgdorferi sensu lato. Between May and October 2001, a total of 1,754 ticks were collected by blanket dragging; 374 ticks were analyzed for B. burgdorferi sensu lato by both an immunofluorescence assay (IFA) and at least two different PCR tests, whereas 171 ticks were analyzed by PCR only. By combining all assays, an average of 14% of the ticks tested positive for B. burgdorferi sensu lato, 5.5, 15.8, and 21.8% in the three collection areas. Of the nymphs and adults examined, 12.9 and 21.1%, respectively, were found to be spirochete infected. A lower total infection prevalence was obtained by IFA (14.4%) than by a nested PCR approach (16.5%), but both were higher than that obtained by a simple PCR approach (11.9%). Compared with data collected over a decade ago, the mean infection prevalence of B. burgdorferi sensu lato in the ticks was significantly higher for all three biotopes, whereas a similar pattern of habitat-specific infection prevalence was observed. Genotyping of B. burgdorferi sensu lato revealed high relative prevalences of B. valaisiana (identified in 43.1% of infected ticks) and B. garinii (32.3%), whereas B. afzelii (12.3%) and B. burgdorferi sensu stricto (1.5%) were relatively rare. We conclude that B. burgdorferi sensu lato infection has increased in this region over the last 15 years due to presently unknown changes in ecological conditions, perhaps related to climate change or wildlife management.

Opportunistic properties of Nosema algerae (Microspora), a mosquito parasite, in immunocompromised mice.

ABSTRACT. In the last ten years microspordia have been recognized as opportunistic pathogens in AIDS patients. The sources of infection and the mechanisms of transmission of these organisms in humans are mostly uncertain. Transmission of invertebrte microsporidia to mammals is normally considered impossible, temperature being a limiting factor for development. Mice treated with cortisone acetate and with cyclosporin A, respectively, as well as athymic mice were injected intravenously, intranasally, perorally and subcutaneously with spores of Nosema algerae, a microsporidian species of culicine mosquitoes. No infection could be detected in tissue samples of cortisone acetate and cyclosporin A treated mice. However, the experimental inoculation of spores into the tail and foot of athymic mice caused severe infection in skeletal muscles and the connective tissue. In some tails, nerve tissue and bone marrow were also infected. Vegetative stages and spores were seen in direct contact to host cell cytoplasma. For the first time the prolonged and progressive development of an invertebrate microsporidium in a mammalian host is shown. The possibility of invertebrate microsporidia as a source of human microsporidiosis should now be taken into consideration.

Ribosomal RNA of Nosema algerae and phylogenetic relationship to other microsporidia

Abstract Microsporidia are intracellular parasites that are common in invertebrates. Taxonomic classification is mostly restricted to morphologic and physiologic data. Limited data are available about taxonomic classification using DNA-sequence data for analysis. We examined the small-subunit (SSU) rDNA, the intergenic spacer (ITS) region, and a part of the large-subunit (LSU) rDNA of Nosema algerae, a parasite of mosquitoes, taken from a laboratory colony of Anopheles stephensi. Target gene amplifications were done by polymerase chain reaction (PCR) and, after cloning, DNA fragments were sequenced. The SSU-rDNA sequence obtained was aligned with several other microsporidian SSU-rDNA sequences available from the GenBank or EMBL data bases and was analyzed by different methods. On the basis of the results of our phylogenetic analysis, we suggest that our N. algerae isolate is not closely related to other microsporidia belonging to the genus Nosema.

Concomitant infections of anopheles stephensi with plasmodium berghei and serratia marcescens: Additive detrimental effects*

The mortality rate of Anopheles stephensi increased after infection with Plasmodium berghei and correlated negatively with temperature. Development of oocysts is inhibited at temperatures above 21 degrees C. We tested the hypothesis that microorganisms were involved in killing the mosquitoes. In fact we were able to demonstrate that in our A. stephensi colony great numbers of Serratia marcescens could be found in the midgut of the insects. The highest value was 2.3 x 10(7) cfu/ml. Other bacteria were rarely seen (1 out of 30 females had flavobacteria). Serratia was neither found in larvae and pupae nor in the water of the breeding dishes. Moderate numbers were detectable in glucose solutions (for feeding of adult mosquitoes) as well as in jars where pupae emerged. Isolated Serratia strains grew faster at 25 degrees C than at 21 degrees C. In glucose solutions alone growth rates were low but they rose rapidly after the addition of blood. -In experimental infections of A. stephensi with S. marcescens (1 x 10(7) bacteria/ml glucose solution) the mortality increased at 25 degrees C. At 21 degrees C the effect of Serratia was insignificant whereas in P. berghei-infected A. stephensi the damaging effects of migrating ookinetes were obvious. Additive detrimental effects were observed at 25 degrees C in mosquitoes infected with P. berghei and Serratia concomitantly.

IS STAGE CONVERSION THE INITIATING EVENT FOR REACTIVATION OF TOXOPLASMA GONDII IN BRAIN TISSUE OF AIDS PATIENTS

Reactivation of chronic toxoplasmosis resulting in Toxoplasma encephalitis (TE) is a common event in acquired immune deficiency syndrome (AIDS) patients. Conversion from Toxoplasma gondii bradyzoites to tachyzoites is a prerequisite for reactivation. Until recently, the study of stage conversion in human tissue was not possible due to the lack of antibodies that recognize stage-specific epitopes after long-term formaldehyde fixation. Using the combination of a polyclonal anti-T. gondii antibody, the cyst-stage-specific monoclonal antibody CC2, and a tachyzoite-specific polyclonal antibody (anti-SAG1, recombinant), we tried to demonstrate parasite differentiation in the brain tissue of 10 AIDS patients with clinically suspected TE. Double labeling of the stage-specific antibodies enabled us to demonstrate interconversion between tachyzoites and bradyzoites for the first time in human tissue. The study confirmed that the transformation process is nonsynchronous and that the manifestation of TE depends on the degree and site of tissue destruction caused by invading tachyzoites. The original source of tachyzoites could never be located, but a few samples suggested that tachyzoites may invade by dissemination across the blood–brain barrier. Cyst rupture as the first event in the process of reactivation was not seen. We conclude that the initial site(s) of reactivation will be destroyed by tissue-destructive tachyzoites long before clinical symptoms occur.

In Vitro Replication of Nosema algerae (Microsporidia), a Parasite of Anopheline Mosquitoes, in Human Cells above 36° C

Microsporidia form a large and ubiquitous group of obligately intracellular parasitic eukaryotes, increasingly recognized as pathogens in humans. Transmission of invertebrate microsporidia to mammals has been considered impossible because temperature seemed to be a limiting factor for development. Nosema algerae, a microsporidian of anopheline mosquitoes, was cultured in human muscle fibroblasts at temperatures of 31° C and 38° C. This is the first record of an invertebrate microsporidian developing in human cells at a temperature above 36° C. The ultrastructure of N. algerue growing in human muscle fibroblasts is similar to that of Bruchiola vesicularum, a microsporidian species previously described in the muscle of an AIDS patient.

Giardia and Cryptosporidium in backwash water from rapid sand filters used for drinking water production.

Backwash water from rapid sand filters of a treatment plant using surface water from small rivers for drinking water production was examined with the aim of determining the degree of their potential contamination with Giardia cysts and Cryptosporidium oocysts. Simultaneous investigations were carried out for both protozoans from November 1993 to February 1994. Water samples were concentrated by continuous flow centrifugation (11 backwash water samples) or by using polypropylene cartridge filters (12 raw water samples and 39 backwash water samples). Parasites were identified by the direct immunofluorescence assay. Ten out of 12 raw water samples tested were positive for Giardia (range: 2-103/ 100 L) and 8 out of 12 were positive for Cryptosporidium (range: 0.8-109/100L). Eight of 11 backwash water samples collected by continuous flow centrifugation were positive for Giardia (range: 3-86/100 L) or Cryptosporidium (range: 1-69/100 L). Out of 39 samples collected using cartridge filters, 34 were positive for Giardia (range: 1.4-374/100 L) and 33 for Cryptosporidium (range: 0.8-252/100 L). Overall, Giardia, Cryptosporidium, or both were detected in 92% of the backwash water samples. The results have clearly shown that backwash waters were contaminated with Giardia and Cryptosporidium and the supernatant returned to the raw water after the sedimentation process was not free from cysts and oocysts.