Search

Cryptosporidium is a parasite that causes watery diarrhea among both children and adults. However, because many physicians do not routinely ask for Cryptosporidium diagnostic test, cryptosporidiosis prevalence is likely underestimated. The current study investigated the prevalence of cryptosporidiosis among children admitted to the hospital with gastrointestinal symptoms. Stool sample was collected from each child and subjected to routine microbiological culture. Cryptosporidium presence was tested by three different methods: real-time PCR (RT-PCR), quick antigen, and microscopic examination with acid-fast staining. Each positive specimen was further tested with BioFire FilmArray Multiplex PCR (bioMerieux SA, Marcy-l'Etoile, France) to determine that Cryptosporidium is the only pathogen in the sample. Demographic and epidemiological data were collected from the patients' medical records. Of 291 patient stool samples, nine were positive for Cryptosporidium hominis or Cryptosporidium parvum. The average age of the nine Cryptosporidium-positive cases was 2.3 years, lower than the average age of the study population (4.2 years). Of the positive cases, 66.7% were Arabs and 33.3% were Jews. The main complaint of children with Cryptosporidium was diarrhea. Regarding the laboratory methods for Cryptosporidium identification, of the positive samples, 100% (9/9) were identified by RT-PCR, 88% (8/9) were positive by antigen test, and only 67% (6/9) were positive by microscopic examination with acid-fast staining. Because of the low incidence of Cryptosporidium among patients in our facility, the prevalence of cryptosporidiosis still cannot be established. Nevertheless, among the other pathogens found in stool samples, Cryptosporidium is the second leading cause of hospitalization due to gastrointestinal disease in children in our area.

Pertussis is the only vaccine-preventable disease that has re-emerged in Israel. In the last two decades, despite high primary immunization coverage, crude incidence increased over tenfold, with especially high morbidity among infants and adolescents and with 19 infant deaths. Two pertussis vaccine boosters were added, in 2005 for 7-year-olds and in 2011 for 13-year-olds. We reviewed age group incidence from 1999 to 2016, before and after the booster program introduction. We compared three groups of 13-15 year-olds with identical primary immunization but different booster immunization histories. Vaccine effectiveness was calculated before and after adjustment for specific incidence in those aged 65 and over. Two years after one booster, adjusted vaccine effectiveness was 74.5%. Two years after two boosters, adjusted vaccine effectiveness was 91.8%. However, crude morbidity rates were not reduced. The booster program has been effective only among recipient groups. The program will be continued. Israel is now encouraging pregnant women to be vaccinated against pertussis to improve protection of infants.

Cryptosporidium is a parasite that causes watery diarrhea among both children and adults. However, because many physicians do not routinely ask for Cryptosporidium diagnostic test, cryptosporidiosis prevalence is likely underestimated. The current study investigated the prevalence of cryptosporidiosis among children admitted to the hospital with gastrointestinal symptoms. Stool sample was collected from each child and subjected to routine microbiological culture. Cryptosporidium presence was tested by three different methods: real-time PCR (RT-PCR), quick antigen, and microscopic examination with acid-fast staining. Each positive specimen was further tested with BioFire FilmArray Multiplex PCR (bioMérieux SA, Marcy-l'Etoile, France) to determine that Cryptosporidium is the only pathogen in the sample. Demographic and epidemiological data were collected from the patients’ medical records. Of 291 patient stool samples, nine were positive for Cryptosporidium hominis or Cryptosporidium parvum. The average age of the nine Cryptosporidium-positive cases was 2.3 years, lower than the average age of the study population (4.2 years). Of the positive cases, 66.7% were Arabs and 33.3% were Jews. The main complaint of children with Cryptosporidium was diarrhea. Regarding the laboratory methods for Cryptosporidium identification, of the positive samples, 100% (9/9) were identified by RT-PCR, 88% (8/9) were positive by antigen test, and only 67% (6/9) were positive by microscopic examination with acid-fast staining. Because of the low incidence of Cryptosporidium among patients in our facility, the prevalence of cryptosporidiosis still cannot be established. Nevertheless, among the other pathogens found in stool samples, Cryptosporidium is the second leading cause of hospitalization due to gastrointestinal disease in children in our area.

Every year Christian pilgrims from around the world visit the holy sites located around the Sea of Galilee. Some become ill during their stay with infectious diseases that were acquired in their country of origin, and are hospitalized at Poriya Medical Center. They pose a diagnostic challenge due to language barriers, the rarity of these infections in Israel, and the fact that diagnostic tests are not readily available. All patient records from 2015 of Holy Land tourists hospitalized at Poriya Medical Center were screened for the diagnosis of imported zoonotic diseases that are not commonly diagnosed in Israel. Three patients who were on a Holy Land tour were hospitalized during 2015 with laboratory-confirmed diagnostically challenging zoonotic infectious diseases: a 91-year-old priest from Ethiopia diagnosed with relapsing fever due to Borrelia recurrentis, an 85-year-old retired mountaineer from New Hampshire diagnosed with human granulocytic anaplasmosis, and a 57-year-old farmer from central Brazil diagnosed with leptospirosis. These case reports emphasize the importance of considering imported zoonotic infectious diseases and obtaining appropriate diagnostic tests when treating Holy Land travelers to Israel.

Blood samples from 18 tickborne relapsing fever (TBRF) patients and Ornithodoros tholozani specimens were tested with a Borrelia flaB-PCR. Results were positive for all patients and 2%–40% of ticks. A 7–amino acid gap characterized all 9 sequenced flagellin gene amplicons. By phylogenetic analysis, Israel TBRF Borrelia sequences clustered separately from American and African groups.

Acute liver fluke infection results from eating raw fish illegally imported from Siberia., Liver fluke infection caused by Opisthorchiidae is a major public health problem in many parts of the Far East, Southeast Asia, and eastern Europe. However, with the growing volume of international travel and population migration, the infection is increasingly diagnosed in countries where the disease is not endemic, particularly in North America. We report an outbreak of acute opisthorchiasis in a family that was infected in a non–disease-endemic area after eating raw carp illegally imported from a highly disease-endemic area in Siberia. With the growing numbers of former Soviet Union citizens immigrating to other countries, western physicians need to be alert regarding Opisthorchis-associated pathology in this population. The epidemiology and biology of Opisthorchiidae in the former Soviet Union are reviewed.

During 2002 to 2011, 275 of 6828 children with giardiasis in Israel were reported with recurrent, over 6 months apart, episodes. The only significant multivariable-adjusted risk predictor of a recurrent episode was non-Jewish ethnicity (hazard ratio, 4.61 [95% confidence interval, 3.32-6.40]; P < .001), also accompanied by significant interaction with lower maternal education.

It is hypothesized that abnormal interaction between sickle hemoglobin (HbS) and erythrocyte membrane lipid might promote deposition of denatured hemoglobin (hemichrome) on the membrane. We compared the interaction of HbS and normal HbA with large unilamellar phosphatidylserine (PS) liposomes under low salt/pH conditions. Admixture of oxyHb and dioleoyl-PS resulted in loss of absorbance at 412 nm, the apparent first order rate constant for which was .25 +/- 0.02 hour-1 for HbA and .85 +/- 0.18 hour-1 for HbS. This was ascribable largely to formation of metHb and hemichromes and was accompanied by some actual transfer of heme from hemoglobin to lipid phase. By comparison, admixture of oxyHb with liposomes made from bovine brain PS having unsaturated acyl chains promoted even faster absorbance loss if the starting liposomal material contained detectable peroxidation by-product. In such cases, actual heme destruction developed with accompanying liberation of free iron and promotion of lipidperoxidation. Fluorescence quenching experiments indicate that hemoglobin/lipid interaction is characterized by very rapid initial electrostatic interaction, followed by development of irreversible changes. Similar changes still occur under conditions of physiologic salt/pH, but they develop much more slowly. The 3.4-fold faster oxidation of HbS versus HbA on lipid observed here represents an additional augmentation of the disparity in oxidation rates for hemoglobins in solution (1.7-fold faster for HbS than for HbA) observed previously. The accelerated promotion of Hb denaturation resulting from lipid contact may help explain deposits of hemichrome on sickle red blood cell membranes, particularly because these cells are in double jeopardy by virtue of having both the mutant HbS and abnormal amounts of peroxidized membrane lipid.

We report seven cases of false-positive Plasmodium falciparum histidine-rich protein 2 (PfHRP2) malaria assay results in patients with acute schistosomiasis caused by Schistosoma mekongi . PfHRP2 assays were negative in travelers infected with Schistosoma mansoni or Schistosoma haematobium ( n = 13). Malaria was ruled out and rheumatoid factor was negative in all patients.

Microscopic examination is still considered the gold standard for the diagnosis of parasitic diseases. In many clinical laboratories in hospitals and in health maintenance organizations ("Kupot Holim"), an excellent microscopic identification of parasites is performed. Microscopic examinations using wet mount preparations are performed for the detection of protozoan trophozoites and helmintic ova or larvae. Specific concentration techniques, including flotation and sedimentation procedures are further performed for the diagnosis of parasitic diseases. However, microscopic examinations are time-consuming, non-sensitive and not always reliable. Furthermore, the diagnosis of certain infections is not always possible by searching for the parasites in host tissues or excreta since risky invasive techniques might be necessary to locate the parasites. Detection of antibodies can be very useful as an indication for infection with a specific parasite, especially in individuals with no exposure to the parasite prior to recent travel in a disease-endemic area. In addition to serology, there are other tests of high sensitivity which can be integrated with microscopy, such as antigen detection in stool and blood samples as well as the use of other molecular diagnosis methods. There are two main laboratories in Israel where parasitic diagnosis is available by integration of microscopy, serology, antigen detection and molecular methods: The Reference Laboratory for Parasitology in Jerusalem at the Central Laboratories of the Ministry of Health (MOH) and the Laboratory of Parasitology at Soroka University Medical Center, Beer Sheva (SOR). There are also two special diagnostic units, one responsible for the identification of toxopLasma: Reference Laboratory for Toxoplasmosis, Public Health Laboratory, Ministry of Health, Tel Aviv (Tox), and the other for the identification of Leishmaniasis: Kuvin Center, Faculty of Medicine, Hebrew University of Jerusalem (Kuv). This article summarizes the tests which are currently available for the diagnosis of parasites in Israel and specifies the laboratories in which they can be performed.

Based on the unusually high and stage-dependent susceptibility of Plasmodia to oxidant stress it has been proposed that during parasite development, increasing levels of redox-active forms of iron are gradually released. The purpose of this study was to examine this proposal by using an assay monitoring the levels of available forms of iron for redox reactions. Ascorbate-driven and iron-mediated degradation of adventitious DNA served as the basis for this functional assay. Incubation of DNA with lysate from infected RBC caused massive degradation, which was dose, time- and parasite-stage dependent. In contrast, lysate from non-infected RBC did not induce DNA degradation. Likewise, lysate only from infected RBC enhanced the aerobic oxidation of ascorbate. These effects on both reaction, DNA degradation and ascorbate oxidation, could be reconstructed with hemin, instead of lysate. Also, chelators exerted similar effects on both reactions. The results suggest that increased levels of redox-active forms of iron are liberated during parasite development. We propose that hemin or hemin-like structures are the appropriate candidates which could catalyze oxidative stress and deregulate the delicate redox balance of the host-parasite system.

The identification of the Tick Borne Relapsing Fever (TBRF) agent in Israel and the Palestinian Authority relies on the morphology and the association of Borrelia persica with its vector Ornithodoros tholozani. Molecular based data on B. persica are very scarce as the organism is still non-cultivable. In this study, we were able to sequence three complete 16S rRNA genes, 12 partial flaB genes, 18 partial glpQ genes, 16 rrs-ileT intergenic spacers (IGS) from nine ticks and ten human blood samples originating from the West Bank and Israel. In one sample we sequenced 7231 contiguous base pairs that covered completely the region from the 5′end of the 16S rRNA gene to the 5′end of the 23S rRNA gene comprising the whole 16S rRNA (rrs), and the following genes: Ala tRNA (alaT), Ile tRNA (ileT), adenylosuccinate lyase (purB), adenylosuccinate synthetase (purA), methylpurine-DNA glycosylase (mag), hypoxanthine-guanine phosphoribosyltransferase (hpt), an hydrolase (HAD superfamily) and a 135 bp 5′ fragment of the 23S rRNA (rrlA) genes. Phylogenic sequence analysis defined all the Borrelia isolates from O. tholozani and from human TBRF cases in Israel and the West Bank as B. persica that clustered between the African and the New World TBRF species. Gene organization of the intergenic spacer between the 16S rRNA and the 23S rRNA was similar to that of other TBRF Borrelia species and different from the Lyme disease Borrelia species. Variants of B. persica were found among the different genes of the different isolates even in the same sampling area.

Foodborne Salmonella enterica outbreaks constitute both a threat to public health and an economic burden worldwide.To characterize the pathogen(s) involved and possible source of infection of an outbreak of acute gastroenteritis in a banqueting hall in Jerusalem.We conducted interviews of guests and employees of the banqueting hall, and analyzed food items, samples from work surfaces and stool cultures.Of 770 persons participating in three events on 3 consecutive days at a single banqueting hall, 124 were interviewed and 75 reported symptoms. Salmonella enterica, serovar Enteritidis, phage type C-8, was isolated from 10 stool cultures (eight guests, one symptomatic employee and one asymptomatic employee) and a sample of a mayonnaise-based egg salad. Pulsed-field gel electrophoresis of the isolates revealed an identical pattern in the outbreak isolates, different from SE C-8 controls. A culture-positive asymptomatic employee was linked to all three events. After a closure order, allowing for cleaning of the banqueting hall, revision of food preparation procedures and staff instruction on hygiene, the banqueting hall was reopened with no subsequent outbreaks.It is often difficult to pinpoint the source of infection in S. enterica outbreaks. Using molecular subtyping methods, a link was confirmed between patients, a food handler (presumably a carrier) and a food item--all showing an identical specific Salmonella enterica serovar Enteritidis. Testing asymptomatic as well as symptomatic food handlers in outbreak investigations is imperative. Pre- and post-hiring screening might be considered as preventive measures; hygiene and sanitation education are essential.

A standardisation process, already developed during the earlier European Sero-Epidemiology Network (ESEN) project, was employed with a more robust algorithm to harmonise results of pertussis serological assays performed in 12 European and non-European countries. Initially, results from each country's own assay were compared with those obtained at the reference laboratory by means of an in-house pertussis toxin (PT)-based ELISA: seven countries used in-house or commercial PT-ELISAs; the other countries used assays based on Bordetella pertussis whole cell extracts (WCE) (three countries) or on combined PT-FHA (filamentous haemagglutinin) antigenic preparations (two countries). The WCE assays, although admitted for diagnostic purposes, confirmed their low correlation with the PT-ELISAs and their results could not be used for standardisation; the PT-FHA ELISAs gave results that were suitable for standardisation in one country but unsatisfactory in the other; the use of purified PT in serological assays confirmed its better reliability than other preparations and all PT-ELISAs results could be calibrated against those of the reference centre. In the standardisation process two high-titre cut-offs indicative of likelihood of recent infection (from within 4 weeks of disease onset up to 1 year after) were included for evaluations as they are suggested to be more useful, for the sero-epidemiological assays of immunity to pertussis, than the cut-off of protection, commonly employed, but still not defined for pertussis. Providing PT-ELISAs are used, standardisation of pertussis assay results is always possible and, when standardisation is performed, evaluation and comparison of the impact of different interventions can be also allowed, by measuring at the distribution of high antibody titres in the populations.

Schistosomiasis is increasingly encountered among travelers returning from the tropics; signs and symptoms of travelers may differ from those of local populations. During 1993-2005, schistosomiasis was diagnosed in 137 Israeli travelers, most of whom were infected while in sub-Saharan Africa. Clinical findings compatible with acute schistosomiasis were recorded for 75 (66.4%) patients and included fever (71.3%), respiratory symptoms (42.9%), and cutaneous symptoms (45.2%). At time of physical examination, 42 patients (37.1%) still had symptoms of acute schistosomiasis, chronic schistosomiasis had developed in 23 (20.4%), and 48 (42.5%) were asymptomatic. Of patients who were initially asymptomatic, chronic schistosomiasis developed in 26%. Diagnosis was confirmed by serologic testing for 87.6% of patients, but schistosome ova were found in only 25.6%. We conclude that acute schistosomiasis is a major clinical problem among travelers, diagnostic and therapeutic options for acute schistosomiasis are limited, and asymptomatic travelers returning from schistosomiasis-endemic areas should be screened and treated.

Contamination of food with streptococci could present with unusual outbreaks that may be difficult to recognize in the early stages. This is demonstrated in a large food-borne outbreak of streptococcal pharyngitis that occurred in 2003 in a factory in Israel. The outbreak was reported to the public health services on July 2 and an epidemiologic investigation was initiated. Cases and controls were interviewed and throat swabs were taken. An estimated 212 cases occurred within the first 4 days, the peak occurring on the second day. There was a wave of secondary cases during an additional 11 days. The early signs were of a respiratory illness including sore throat, weakness and fever, with high absenteeism rates suggesting a respiratory illness. As part of a case-control study, cases and controls were interviewed and throat swabs taken. Illness was significantly associated with consumption of egg-mayonnaise salad (odds ratio 4.2, 95% confidence interval 1.4-12.6), suggesting an incubation period of 12-96 hours. The initial respiratory signs of food-borne streptococcal pharyngitis outbreaks could delay the identification of the vehicle of transmission. This could be particularly problematic in the event of deliberate contamination.

Pertussis is the only vaccine-preventable disease that has re-emerged in Israel. The reported crude incidence of the disease increased 16-fold since 1998.To describe the epidemiology of pertussis and explain the substantial increase in reported pertussis incidence in Israel in recent years.Crude and specific pertussis incidence by age, patient immunization status, hospitalization rate, and national immunization coverage rate were calculated from information provided by the public health offices of the Ministry of Health.The reported crude incidence of pertussis increased from 1-2/100,000 in 1994-98 to 23/100,000 in 2004. The trend was observed in all age groups, being most prominent in infants under age 1 year and in children aged 5-14. The incidence of pertussis was substantially higher in unvaccinated and partly vaccinated compared to fully vaccinated persons. Fifteen percent of notified cases were hospitalized, but in infants under age 1 year the hospitalization rate was 50%. National pertussis immunization coverage by age 2 years was stable during the last 10 years.There are several possible explanations for the re-emergence of pertussis in Israel. The most plausible reason seems to be the waning of vaccine-induced immunity in face of infrequent natural exposure to the infectious agent and lack of a pertussis vaccine booster dose after age 1.

Onchocerciasis results from infestation by the nematode Onchocerca volvulus, and is characterized clinically by troublesome itching, skin lesions and eye manifestations. Since 1992, approximately 9,000 immigrants have arrived in Israel from the Kuwara province of northwest Ethiopia where the prevalence of onchocerciasis is particularly high.To determine whether onchocerciasis is the cause of cutaneous and ocular symptoms among recent immigrants from the Kuwara province in Ethiopia.We examined 1,200 recent immigrants from the Kuwara province residing at the Mevasseret Zion immigration center outside Jerusalem. Among them, patients with cutaneous signs suggestive of onchocerciasis underwent a skin-snip biopsy and a thorough eye examination.In the detailed skin examination performed in 83 patients, the most common skin finding was chronic papular onchodermatitis, found in more than 46 patients (55%); depigmentation and atrophy was found in 13 (15%) and 12 (14%), respectively. In 40 patients (48%), living microfilaria were detected in their skin snips. Of the 65 patients who underwent a through eye examination, 45 patients (66%) had ocular complaints. Corneal abnormalities were found in 55 of the 130 eyes (42%), active anterior segment intraocular inflammation and live microfilariae were found in 4 eyes (3%) and lens changes in 16 eyes (1%). Eleven eyes (9%) showed retinal or choroidal changes.Skin and eye manifestations associated with onchocerciasis are prevalent among symptomatic Ethiopians who immigrated to Israel from the Kuwara province.

We tested 46 fully vaccinated children in two day-care centers in Israel who were exposed to a fatal case of pertussis infection. Only two of five children who tested positive for Bordetella pertussis met the World Health Organization's case definition for pertussis. Vaccinated children may be asymptomatic reservoirs for infection.

OBJECTIVES: Several studies have demonstrated that a large percentage of older people are inadequately immunized against tetanus. The aim of this study was to assess the immunity against tetanus in a group of individuals aged 69 and older and to examine the immune response to a single dose of tetanus toxoid. DESIGN: A convenience sample of 115 residents of a large retirement home, aged 69 and older, was studied. After a blood sample for anti-tetanus antibody titer, a single dose of tetanus toxoid vaccine was administered. Repeat titers were obtained 6 weeks after the vaccination and analyzed by ELISA assay. Antibody levels equal to or greater than 0.1IU/mL were considered protective. RESULTS: Sixty-seven of 115 (58.3%) individuals had adequate antibody titers. Those individuals who reported having been vaccinated with tetanus toxoid in the past were more likely to be immunized adequately compared with those who reported having never been vaccinated (66.7% vs 39.3%, P = .02). After vaccination, 34 of 46 (73.9%) individuals with inadequate antibody titers became seropositive. Those who remained seronegative had mean prevaccination antibody titers significantly lower than those who seroconverted. Sixteen of 17 (94.1%) persons who reported having been vaccinated in the past and were found to be seronegative developed adequate antibody titers following vaccination, compared with only nine of 16 (56.2%) who reported never having been vaccinated (P = .04). There was no association between seroconversion rate and age, sex, underlying diseases, and army service. CONCLUSIONS: Most individuals will develop an adequate anti-tetanus antibody titer following administration of a single dose of tetanus vaccine. A history of past immunization is a good predictor of becoming adequately immunized. It is important that physicians follow the current recommendations for adult immunization and initiate campaigns to ensure that the older population is protected against tetanus.

The role of reactive oxygen species (ROS) generated by polymorphonuclear leucocytes (PMNs) in the host response against malaria was investigated. Non-activated human PMNs were added to cultures of P. falciparum in microtitre cells. Parasite viability was evaluated by the incorporation of radioactive hypoxanthine. Using PMN/RBC = 1/150 (starting parasitemia was 1%) the incorporation on the second day in culture was only 61% of the control cultures. An effect could be observed already after two hours of incubation (30% reduction at a 1/50 PMN/RBC ratio). A direct contact between the effector and target cells was obligatory for the expression of the damage. Parasites within G6PD-deficient erythrocytes were more sensitive to the PMNs than normal parasitized erythrocytes. This difference could be attributed to the production of reactive oxygen intermediates in the experimental system, since G6PD-deficient erythrocytes are generally more sensitive to oxidant stress. Salicylic acid was used as a scavenger and reporter molecule for hydroxyl radical fluxes. It is converted to the corresponding dihydroxybenzoic acid derivatives, which could be detected by HPLC. Uninfected NRBC or parasitized erythrocytes containing young ring forms could trigger the PMNs to produce much less ROS than the mature forms of the parasites. Other factors associated with PMNs may inactivate the parasites, such as phagocytosis, lysosomal enzymes or degradation toxic products of the PMNs. However our results indicate that increased oxidative stress induced by PMNs interfere with the growth of P. falciparum and could play a role in human evolution of abnormal erythrocytes.

The role of transition metals in paraquat toxicity was studied in cultures of Plasmodium falciparum. We showed that addition of copper led to an enhancement of the plasmodium killing, whereas addition of chelating agents. such as desferrioxamine and diethylenetriamine pentaacetic acid markedly reduced the toxic effects. Parsitized G6PD deficient erythrocytes were more sensitive than parasitized normal eryth-rocytes to copper and to the combination of copper and paraquat.

Oxidative stress has been incriminated as a deleterious factor in the development of malaria parasites. Various chemical reductones which can undergo cyclic oxidation and reduction, such as ascorbate have been shown to cause oxidative stress to red blood cells. This, naturally-occurring and redox-active compound, can induce the formation of active oxygen derived species, such as superoxide radicals (*O;), hydrogen peroxide (H,O,) and hydroxyl radical (OH.). The formation of the hydroxyl radical, the ultimate deleterious species, is mediated by the redox-active and available transition metals iron and copper in the Haber-Weiss reaction. During the development of the parasite, hemoglobin is progressively digested and a concurrent release of high levels of iron-containing breakdown products takes place within the red blood cell. Indications for the progressive increase in redox-active iron during the growth of P. falciparunr have bcen recently found in our lab: a) adventitious ascorbatc proved highly detrimental to the parasite when added to the mature forms. In contrast, if the parasitized erythrocytes were in the early phase following invasion, and only low levels of iron-containing structures had been liberated. then the observed effect was a small promotion of parasite development. b) erythrocytes containing mature parasites were more potent than erythrocytes containing ring forms as a source for redox-active iron in the ascorbate-driven metal-mediated degradation of DNA. The addition of extracts from parasitized erythrocytes and ascorbate to DNA causcd a dose and time dependent DNA degradation. Non-infected erythrocytes had no effect. These findings could also propose that the parasite-dependent accumulation of redox-active forms of iron within the erythrocytes serve as a biological clock triggering the rupture of the red blood cell membrane at the right moment, when the parasite reaches its maturity.

Goldenser J., Marva E., Spira D. T., Gabrielsen A. A. and Jensen J. B. 1985. Mitogenic and antigenic activity of Plasmodium falciparum in primate and rodent lymphocytes. International Journal for Parasitology 15: 435–440. Considerable reaction of human leucocytes to a wide range of concentrations of plasmodial preparations derived from in vitro cultures of Plasmodium falciparum was observed. Highest responses were recorded after 6 days in culture. This differed from the response to PHA or CON-A which peak with a narrow range of concentrations after 3 days in culture. Parasitized erythrocytes (PE) or parasites released from PE as well as soluble antigens obtained from the particulate preparations had a pronounced mitogenic activity which was unaffected by heating to 56°C for 1 h. Peripheral lymphocytes from man and monkey but not from rats reacted to P. falciparum preparations. Spleen cells obtained from normal rats did not react towards any P. falciparum preparation. Spleen cells of rats immune to P. berghei, responded to normal human erythrocytes but the response against P. falciparum antigens was much higher, indicating cross-reactivity with genus specific antigens. The combination of experimental procedures using human peripheral and rat spleen lymphocytes is suggested for differentiation between mitogenic and antigenic activity. Heat inactivation of some proteases present in the plasmodial preparations, while retaining mitogenic activity, may enable further purification of the mitogenic factors.

Synaptic plasma membrane vesicles isolated from rat brain were loaded with L-glutamate either passively, by using a freeze-thaw technique, or by active transport. Subsequently the ion dependency of glutamate efflux from these vesicles was studied. With each of the types of loading similar results were obtained. Efflux requires the simultaneous presence of internal sodium ions and external potassium ions. The process is also stimulated by chloride ions, but either internal or external chloride ions cause stimulation. Addition of unlabeled L-glutamate stimulates efflux about 2-fold. It is concluded that efflux of L-glutamate is in many aspects symmetrical with its influx [Kanner, B. I., & Sharon, I. (1978) Biochemistry 17, 3949--3954]. It appears that in order for L-glutamate to interact with the transporter, sodium has to be present on the same side as L-glutamate whereas potassium has to be simultaneously present on the opposite site. The simplest way to account for these and the previous data is to postulate that the L-glutamate transporter catalyzes sodium and L-glutamate cotransport, while it simultaneously catalyzes antiport of potassium.

The effects of ascorbate and copper on the development of Plasmodium falciparum were studied in two modes: pretreatment of uninfected erythrocytes followed by infection by P. falciparum and treatment of parasitized erythrocytes. Pretreatment of G6PD(+) cells with ascorbate caused a slight enhancement in parasite development, while in G6PD(-) cells a suppressive effect on the plasmodia was demonstrated. Copper alone interfered with parasite growth in both cell types. The combination of copper and ascorbate arrested parasite maturation, an effect which was more pronounced in G6PD(-) cells. Synergism between copper and ascorbate was better demonstrated following the treatment of infected erythrocytes: while ascorbate alone supported parasite development and copper alone had only a marginal suppressive effect, the combination of copper and ascorbate yielded a marked inhibition of parasite growth. Ascorbate proved destructive to the parasites in the presence of adventitious copper, or on the second day of the parasite life cycle. In these cases it acted as a pro-oxidant, while in other systems, in particular in the presence of a chelator, ascorbate acted as an antioxidant and promoted parasite growth. The understanding of the role of transition metals and free radicals in parasite development and injury could shed light on novel approaches to fight malaria.