Effect of biannual azithromycin distribution on antibody responses to malaria, bacterial, and protozoan pathogens in Niger.

The MORDOR trial in Niger, Malawi, and Tanzania found that biannual mass distribution of azithromycin to children younger than 5 years led to a 13.5% reduction in all-cause mortality (NCT02048007). To help elucidate the mechanism for mortality reduction, we report IgG responses to 11 malaria, bacterial, and protozoan pathogens using a multiplex bead assay in pre-specified substudy of 30 communities in the rural Niger placebo-controlled trial over a three-year period (n = 5642 blood specimens, n = 3814 children ages 1-59 months). Mass azithromycin reduces Campylobacter spp. force of infection by 29% (hazard ratio = 0.71, 95% CI: 0.56, 0.89; P = 0.004) but serological measures show no significant differences between groups for other pathogens against a backdrop of high transmission. Results align with a recent microbiome study in the communities. Given significant sequelae of Campylobacter infection among preschool aged children, our results support an important mechanism through which biannual mass distribution of azithromycin likely reduces mortality in Niger.

Serum metabolomics in chickens infected with Cryptosporidium baileyi.

BACKGROUND: Cryptosporidium baileyi is an economically important zoonotic pathogen that causes serious respiratory symptoms in chickens for which no effective control measures are currently available. An accumulating body of evidence indicates the potential and usefulness of metabolomics to further our understanding of the interaction between pathogens and hosts, and to search for new diagnostic or pharmacological biomarkers of complex microorganisms. The aim of this study was to identify the impact of C. baileyi infection on the serum metabolism of chickens and to assess several metabolites as potential diagnostic biomarkers for C. baileyi infection. METHODS: Ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) and subsequent multivariate statistical analysis were applied to investigate metabolomics profiles in the serum samples of chickens infected with C. baileyi, and to identify potential metabolites that can be used to distinguish chickens infected with C. baileyi from non-infected birds. RESULTS: Multivariate statistical analysis identified 138 differential serum metabolites between mock- and C. baileyi-infected chickens at 5 days post-infection (dpi), including 115 upregulated and 23 downregulated compounds. These metabolites were significantly enriched into six pathways, of which two pathways associated with energy and lipid metabolism, namely glycerophospholipid metabolism and sphingolipid metabolism, respectively, were the most enriched. Interestingly, some important immune-related pathways were also significantly enriched, including the intestinal immune network for IgA production, autophagy and cellular senescence. Nine potential C. baileyi-responsive metabolites were identified, including choline, sirolimus, all-trans retinoic acid, PC(14:0/22:1(13Z)), PC(15:0/22:6(4Z,7Z,10Z,13Z,16Z,19Z)), PE(16:1(9Z)/24:1(15Z)), phosphocholine, SM(d18:0/16:1(9Z)(OH)) and sphinganine. CONCLUSIONS: This is the first report on serum metabolic profiling of chickens with early-stage C. baileyi infection. The results provide novel insights into the pathophysiological mechanisms of C. baileyi in chickens.

Plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

We hypothesize that some amino acid abnormalities in diarrheic calves are useful for understanding intestinal mucosal damage, as in humans. However, few reports have revealed the relationship between intestinal mucosal damage and plasma amino acids in diarrheic calves. Therefore, the aim of present study was to investigate whether there is a relationship between the amino acid status and plasma diamine oxidase (DAO) activity, which is known to be a biomarker for intestinal mucosal damage in diarrheic calves. Twenty Holstein calves aged 12.6 ± 4.2 days old were enrolled in this study. In the diarrhea group (n = 10), there were yellow loose feces within the rectum and Cryptosporidium parvum (C. parvum) was detected in all fecal samples. These calves were clinically normal except for diarrhea. All calves in the control group (n = 10) appeared to be healthy based on clinical findings with normal feces production and the absence of C. parvum. Plasma amino acid concentrations and DAO activity were measured. The relationships between plasma DAO activity and the concentration of each plasma amino acid were investigated using Spearman's rank test. The plasma DAO activity was significantly lower in the diarrhea group (176.1 ± 60.1 IU mL-1) than in the control group (309.3 ± 74.8 IU mL-1) (p < 0.001). Furthermore, positive correlations were observed when comparing plasma DAO activity with histidine, proline, cystine, arginine, and glutamine concentrations. As a result of relationship between plasma DAO activity and amino acid status, it was concluded that plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

Seroprevalence of antibodies against Chlamydia trachomatis and enteropathogens and distance to the nearest water source among young children in the Amhara Region of Ethiopia.

The transmission of trachoma, caused by repeat infections with Chlamydia trachomatis, and many enteropathogens are linked to water quantity. We hypothesized that children living further from a water source would have higher exposure to C. trachomatis and enteric pathogens as determined by antibody responses. We used a multiplex bead assay to measure IgG antibody responses to C. trachomatis, Giardia intestinalis, Cryptosporidium parvum, Entamoeba histolytica, Salmonella enterica, Campylobacter jejuni, enterotoxigenic Escherichia coli (ETEC) and Vibrio cholerae in eluted dried blood spots collected from 2267 children ages 0-9 years in 40 communities in rural Ethiopia in 2016. Linear distance from the child's house to the nearest water source was calculated. We derived seroprevalence cutoffs using external negative control populations, if available, or by fitting finite mixture models. We used targeted maximum likelihood estimation to estimate differences in seroprevalence according to distance to the nearest water source. Seroprevalence among 1-9-year-olds was 43% for C. trachomatis, 28% for S. enterica, 70% for E. histolytica, 54% for G. intestinalis, 96% for C. jejuni, 76% for ETEC and 94% for C. parvum. Seroprevalence increased with age for all pathogens. Median distance to the nearest water source was 473 meters (IQR 268, 719). Children living furthest from a water source had a 12% (95% CI: 2.6, 21.6) higher seroprevalence of S. enterica and a 12.7% (95% CI: 2.9, 22.6) higher seroprevalence of G. intestinalis compared to children living nearest. Seroprevalence for C. trachomatis and enteropathogens was high, with marked increases for most enteropathogens in the first two years of life. Children living further from a water source had higher seroprevalence of S. enterica and G. intestinalis indicating that improving access to water in the Ethiopia's Amhara region may reduce exposure to these enteropathogens in young children.

Development of CpGP15 recombinant antigen of Cryptosporidium parvum for detection of the specific antibodies in cattle.

The infection of neonatal calves with Cryptosporidium parvum can have a huge economic impact because diarrhea caused by the parasite sometimes results in death. A serodiagnostic system will be helpful in the diagnosis of C. parvum infection. CpP23 is commonly used as an antigen for enzyme-linked immunosorbent assay (ELISA); however, some positive sera show low reactivities, as shown in this study. Herein, we focused on three other antigens, CpGP15, CpP2 and CpGP60, in addition to CpP23, to detect C. parvum-specific antibodies in cattle sera. CpP23 and CpGP15 showed substantial ability to discriminate between positive (n = 10) and negative (n = 10) control cattle sera. Unlike our previous report, both the sensitivity and the specificity were 100% when the two antigens were employed for the ELISA. The newly developed ELISA was applied to a total of 344 sera obtained from 9 cattle farms. Two farms among them had suffered from C. parvum infections before, and were regarded as the C. parvum-positive farms. The positive rates of antibodies against CpP23 and CpGP15 in the C. parvum-positive farms were 42.7% and 49.8%, respectively, whereas the positive rate for either of the antigens was 63.0% in the farms. In contrast, 14.3% and 9.8% were positive for CpP23 and CpGP15 in the C. parvum-negative farms, respectively, whereas 18.8% was positive for either of the antigens. This study revealed that the ELISAs employing both of CpP23 and CpGP15 can avoid false-negative results and are useful for monitoring of the C. parvum infection in cattle farms.

Treatment of cryptosporidiosis in captive green iguanas (Iguana iguana).

There are no standard guidelines for the treatment of cryptosporidiosis in reptiles. The aim of this study was to evaluate the efficacy of two cryptosporidiosis therapies in captive green iguanas. Eight green iguanas aged 2-6 years, including 6 (1 ♂ and 5 ♀) animals with chronic diarrhea, received treatment for cryptosporidiosis. The presence of Cryptosporidium sp. oocysts was determined in 8 iguanas (100%), Isospora sp. oocysts were detected in 3 animals (37.5%), and Oxyuridae eggs were observed in 5 iguanas (62.5%). The animals were divided into two therapeutic groups (A and B). Group A iguanas were administered halofuginone (Halocur, 0,50 mg/ml Intervet Productions S.A., France) at a dose of 110 mg/kg body weight (BW) every 7 days for 5 weeks. Group B animals were administered sulfadiazine and trimethoprim (Norodine Vet Oral Paste sulfadiazine 288,3 mg/g, trimethoprim 58 mg/g, ScanVet Animal Health A/S, Denmark) at 75 mg/kg BW per os every 5 days for 5 weeks and spiramycin and metronidazole (Stomorgyl, spiramycin 1500000 IU, metronidazole 250 mg, Merial, France) at 200 mg/kg BW every 5 days for 5 weeks. Both groups received hyperimmune bovine colostrum and subcutaneous fluids. Before treatment, the average number of Cryptosporidium sp. oocysts in 1 g of feces was determined at 1.71 * 105 (±313,262.44) in group A and 1.56 * 105 (±262,908.53) in group B; the average number of Isospora sp. oocysts was determined at 3.53 * 103 (±1747.38), and the average number of Oxyuridae eggs was determined at 810 (±496.74). Blood tests were performed once before treatment. The results of blood morphology and biochemistry tests before treatment revealed leukocytosis with a significant increase in heterophile and monocyte counts in all animals. Dehydration, elevated hematocrit values and low levels of Na+, Ca2+, PO4- and Cl- ions were observed in 6 iguanas. Two iguanas died during treatment. The gross necropsy revealed acute inflammation of gastric and duodenal mucosa, mucosal ecchymoses in the gastrointestinal tract, hepatomegaly and liver congestion, cholecystitis, enlarged kidneys and renal edema and congestion, cystitis, and an absence of fat bodies. Parasites were not detected in any developmental form after 40 days of therapy and during an monthly 18-month follow-up period. Effective treatment of cryptosporidiosis in reptiles minimizes the adverse consequences of disease, improves the animals' well-being and decreases euthanasia rates.

First detection of Cryptosporidium DNA in blood and cerebrospinal fluid of HIV-infected patients.

Human cryptosporidiosis is an intestinal infection caused by different species belonging to the genus Cryptosporidium in both immunocompetent and immunocompromised individuals. The life cycle of Cryptosporidium sp. when affecting the digestive system is well known but the infection of other organs is less studied. Molecular methods are necessary for species and subtypes identification. The goal of this work is to propose a new approach that contributes to the diagnosis of the extra-intestinal dissemination process of Cryptosporidium infection. Cryptosporidium sp. was detected in stool and biopsy samples of two HIV-infected patients. DNA was extracted from feces, biopsy specimens, blood, and cerebrospinal fluid (CSF). All samples were analyzed by nested PCR-RFLP of the 18S rDNA, real-time PCR, and gp60 subtyping. Cryptosporidium DNA was detected in stool and tissue samples and it was also present in blood and CSF samples. Both cases were characterized as Cryptosporidium hominis subtype IeA11G3T3. This is the first report that demonstrates the presence of Cryptosporidium DNA in blood and CSF of HIV-infected patients.

Immunolocation and enzyme activity analysis of Cryptosporidium parvum enolase.

BACKGROUND: Enolase is an essential multifunctional glycolytic enzyme that is involved in many biological processes of apicomplexan protozoa, such as adhesion and invasion. However, the characteristics of enolase in Cryptosporidium parvum, including the location on the oocyst and the enzyme activity, remain unclear. METHODS: The C. parvum enolase gene (cpeno) was amplified by RT-PCR and sequenced. The deduced amino acid sequence was analysed by bioinformatics software. The gene was expressed in Escherichia coli BL21 (DE3) and purified recombinant protein was used for enzyme activity analysis, binding experiments and antibody preparation. The localisation of enolase on oocysts was examined via immunofluorescence techniques. RESULTS: A 1,350 bp DNA sequence was amplified from cDNA taken from C. parvum oocysts. The deduced amino acids sequence of C. parvum enolase (CpEno) had 82.1% homology with Cryptosporidium muris enolase, and 54.7-68.0% homology with others selected species. Western blot analysis indicated that recombinant C. parvum enolase (rCpEno) could be recognised by C. parvum-infected cattle sera. Immunolocalization testing showed that CpEno was found to locate mainly on the surface of oocysts. The enzyme activity was 33.5 U/mg, and the Michaelis constant (K m ) was 0.571 mM/l. Kinetic measurements revealed that the most suitable pH value was 7.0-7.5, and there were only minor effects on the activity of rCpEno with a change in the reaction temperature. The enzyme activity decreased when the Ca2+, K+, Mg2+ and Na+ concentrations of the reaction solution increased. The binding assays demonstrated that rCpEno could bind to human plasminogen. CONCLUSION: This study is the first report of immunolocation, binding activity and enzyme characteristics of CpEno. The results of this study suggest that the surface-associated CpEno not only functions as a glycolytic enzyme but may also participate in attachment and invasion process of the parasite.

Serum Anti-Cryptosporidial gp15 Antibodies in Mothers and Children Less than 2 Years of Age in India.

Little is known about the type and longevity of the humoral response to cryptosporidial infections in developing countries. We evaluated serum antibody response to Cryptosporidium gp15 in 150 sets of maternal, preweaning and postinfection/end-of-follow-up sera from children followed up to 2 years of age to determine the influence of maternal and preweaning serological status on childhood cryptosporidiosis. Fifty two percent (N = 78) of mothers and 20% (N = 30) of children were seropositive preweaning. However, most positive preweaning samples from children were collected early in life indicating transplacental transfer and subsequent rapid waning of antibodies. Although 62% (N = 94) of children had a parasitologically confirmed cryptosporidial infection (detected by stool polymerase chain reaction) during the follow-up, only 54% (N = 51) of children were seropositive postinfection. Given there were striking differences in seropositivity depending on when the sample was collected, even though Cryptosporidium was detected in the stool of the majority of the children, this study indicates that antibodies wane rapidly. During follow-up, the acquisition or severity of cryptosporidial infections was not influenced by maternal (P = 0.331 and 0.720, respectively) as well as the preweaning serological status of the child (P = 0.076 and 0.196, respectively).

Cryptosporidium infection, onsite wastewater systems and private wells in the arid Southwest.

Few prior studies have examined the potential health risks from transmission of enteric parasites via aquifers contaminated by wastewater from onsite systems. A cross-sectional study of 600 residents in households served with either onsite wastewater systems and private wells or city sewer/water systems in three different sites in central New Mexico compared serological responses to Cryptosporidium, a common waterborne infections agent. Study participants completed a short self-administered questionnaire with questions on demographic characteristics, characteristics of the onsite wastewater system and private well, and common risk factors associated with cryptosporidiosis. A sample of household tap water was collected, as well as a blood sample from each study participant to measure IgG responses to antigen groups for Cryptosporidium. Logistic regression analysis showed a significant association between having an onsite wastewater system and private well and the 27-kDa marker for Cryptosporidium in the River Valley site after adjusting for covariates (OR = 1.98; 95% CI = 1.11-3.55). This study, together with one prior study, suggests that the presence of onsite wastewater systems and private wells might be associated with an increased risk of Cryptosporidium infection.

Clinical, serological, and parasitological analysis of snakes naturally infected with Cryptosporidium serpentis.

Infection by Cryptosporidium serpentis is one of the most important diseases in reptiles and is characterized by chronic clinical or subclinical infection and the presence of hypertrophic gastritis, food regurgitation, progressive weight loss, mortality, and intermittent or continuous shedding of oocysts in the feces. The objectives of this study were to standardize an indirect enzyme-linked immunosorbent assay (ELISA) to detect antibodies against C. serpentis and to evaluate the clinical, parasitological, and humoral immune response in snakes naturally infected with C. serpentis. Twenty-one snakes naturally infected with C. serpentis and housed at the Butantan Institute, São Paulo, Brazil, underwent clinical and parasitological analyses for C. serpentis infection through daily records of clinical signs and a monthly survey of fecal shedding of oocysts using the Kinyoun's acid-fast staining. The serological evaluation was performed monthly by indirect ELISA using crude total antigen from oocysts of C. serpentis to detect anti-C. serpentis antibodies. Clinical symptoms consisted of food regurgitation, inappetence, and progressive weight loss. The parasitological analysis revealed intermittent fecal shedding of a variable number of oocysts in all snakes, with positivity in 85.32% (157/184) of the samples. The indirect ELISA was positive in 68.25% (86/126) of the samples. A humoral immune response was observed in most animals; however, fluctuating antibodies levels, leading to alternating positive and negative results, were observed in most snakes.

[Detection of immunity and antioxidant indexes in dairy cows infected with Cryptosporidium].

OBJECTIVE: To detect the immune status and antioxidant system indexes of cows infected with Cryptosporidium. METHODS: Fecal samples of 325 dairy cows were collected at a farm in Anhui and examined by floating saturated solution. 7 positive cows and 7 negative cows from the farm were selected as infection group and non-infection group, respectively. Blood samples were taken from cow's jugular vein before feeding in the morning. 19 indexes of total protein (TP), albumin (ALB), IgG, IgM, IgA, phagocytic rate of white blood cells, T lymphocyte transformation rate, IL-2, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), NO, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), glucose (GLU), triglyceride (TG), Cl-, and Ca2+ were tested, respectively. RESULTS: The infection rate of 325 cows was 31.7% (103/325). The Cryptosporidium was identified as C. andersoni according to the morphology and size of oocysts. Compared with the non-infection group, there was no significant difference in the concentration of TP, ALB, IgM, IgA, GSH-Px, ALT, AST, ALP and Cl- (P > 0.05). The concentration of MDA and NO in the infection group increased by 59.9% and 28.1% (P < 0.05 or 0.01), and that of IgG, SOD, GLU, TG, Ca2+, IL-2 and the activities of T lymphocyte transformation rate, phagocytic rate of white blood cells decreased by 32.9%, 11.1%, 18.6%, 78.9%, 14.5%, 7.0%, 22.0%, and 20.2%, respectively (P < 0.05). CONCLUSION: The change of antioxidant and immune indexes shows that the capability of eliminating free radicals and the immune function have decreased in the Cryptosporidium andersoni-infected cows.

[Development of multiplex microbead immunoassay for detection of specific antibodies against Cryptosporidium parvum].

OBJECTIVE: To develop a multiplex microbead immunoassay for detection of specific antibodies against Cryptosporidium parvum using recombinant proteins CP23, SA35 and SA40. METHODS: By using purified recombinant proteins CP23, SA35 and SA40 as detected antigens, and bovine serum albumin (BSA) as internal control, the four proteins aforementioned were coupled with micro beads and MIA was developed. Then, the efficiency of the coupled proteins was tested, the difference between the single MIA method and the multiple MIA method was compared, and the difference between plates was also compared. RESULTS: The purified proteins and BSA were coupled with microbeads successfully, and the MIA method was developed. Finally, the sensitivity and specificity of MIA method were confirmed. CONCLUSIONS: The multiplicate MIA method could be used to detect multiple antibodies after Cryptosporidium parvum infection, and the specificity and sensitivity of MIA are very high. The multiplicate MIA method can be one of the tools used in epidemiological survey.

[Serological detection of Cryptosporidium spp. infection in outpatients in Changchun].

CP23 gene of Cryptosporidium parvum was expressed in Escherichia coli, and the recombinant protein was purified. Its immunoreactivity was analyzed by Western blotting. Serum samples were collected from outpatients of different ages from August to November, 2010 in Changchun. Indirect ELISA was established to detect the anti-CP23 IgG in sera. Western blotting analysis indicated that the recombinant CP23 protein was recognized by sera from Cryptosporidium panum-infected calves and positive human sera, but not recognized by sera of mice infected with Schistosoma japonicum, sera from falciparum malaria patients and negative human sera. The overall anti-CP23 IgG positive rate was 3.2% (65/2 046). The seropositive rate was 2.7% (28/1 036) in men and 3.7% (37/1 010) in women (P > 0.05). The seropositive rates were significantly different among age groups (P < 0.05), and the age group of 71-80 had the highest positive rate (8.6%, 13/152).

Serum antibody responses to polymorphic Cryptosporidium mucin antigen in Bangladeshi children with cryptosporidiosis.

Cryptosporidium is a significant cause of diarrheal disease in children in developing countries. The sporozoite antigen Muc4 is important for infection of host cells, and could be a candidate vaccine antigen. However, this antigen is polymorphic between Cryptosporidium hominis and C. parvum. We investigated antibody responses to C. hominis Muc4 and C. parvum Muc4 antigen in children in Bangladesh infected with C. hominis. Antibody responses were compared between children with cryptosporidial diarrhea (cases) and uninfected children with diarrhea (controls). There was a significant IgM response to Muc4 from both species in cases compared with controls, which increased over time, and was higher in children with persistent diarrhea. Despite sequence polymorphisms, antibody responses to C. hominis Muc4 and C. parvum Muc4 were significantly correlated. These results suggest that the human antibody response to Muc4 is cross-reactive between species, but in young children does not mature to an IgG response within the period observed in this study.

A hospital-based serological survey of cryptosporidiosis in the Republic of Korea.

The seroprevalence of cryptosporidiosis was examined using patients' sera collected from hospitals located in 4 different areas of the Republic of Korea. ELISA was used to measure antibody titers against Cryptosporidium parvum antigens from a total of 2,394 serum samples, which were collected randomly from patients in local hospitals; 1) Chungbuk National University Hospital, 2) Konkuk University Hospital, 3) local hospitals in Chuncheon, Gangwon-do (province), 4) Jeonnam National University Hospital, from 2002 through 2003. Of the 2,394 samples assayed, 34%, 26%, and 56% were positive for C. parvum-specific IgG, IgM, and IgA antibodies, respectively. Positive IgG titers were most common in sera from Jeonnam National University Hospital, Gwangju, Jeollanam-do, and positive IgM titers were most common in sera from Chungbuk National University Hospital, Cheongju, Chuncheongbuk-do. The seropositivity was positively correlated with age for both the IgG and IgA antibodies but was negatively correlated with age for the IgM antibodies. Western blotting revealed that 92%, 83%, and 77% of sera positive for IgG, IgM, and IgA ELISA reacted with 27-kDa antigens, respectively. These results suggested that infection with Cryptosporidium in hospital patients occurs more commonly than previously reported in the Republic of Korea.

Simultaneous detection of serum immunoglobulin G antibodies to Cryptosporidium parvum by multiplex microbead immunoassay using 3 recognized specific recombinant C. parvum antigens.

Cryptosporidiosis is a significant diarrheal disease in both humans and other mammals worldwide. In the present study, we established and validated a multiplex microbead immunoassay (MIA) for surveillance of Cryptosporidium parvum infections. In the multiplex MIA, 3 specific recombinant proteins, CP23, SA35, and SA40, were used as the capture antigens simultaneously. The antibody directed against CP23 is an index of historic infection, and those against SA35 and SA40 are indices of recent infection. The multiplex MIA yielded essentially identical results with that of monoplex MIA using these 3 recombinant proteins, and the reproducibility of the multiplex MIA results was high when standardized with a calibration curve. With multiplex MIA, we detected that the pediatric population showed a higher percentage of recent infections (seropositive rates of antibodies directed against CP23, SA35, and SA40 were 6.28%, 23.19%, and 22.71%, respectively, n = 207), whereas the adult population showed a higher percentage of historic infections (seropositive rates of antibodies directed against CP23, SA35, and SA40 were 24.40%, 11.48%, and 16.75%, respectively, n = 209).

Dynamics of gut mucosal and systemic Th1/Th2 cytokine responses in interferon-gamma and interleukin-12p40 knock out mice during primary and challenge Cryptosporidium parvum infection.

Cryptosporidium parvum is an intracellular parasite causing enteritis which can become life-threatening in the immunocompromised host. CD4+ T cells and interferon (IFN)-gamma play dominant roles in host immune response to infection. However, effector mechanisms that are responsible for recovery from infection are poorly understood. In the present study we analyzed mice deficient in IFN-gamma or interleukin (IL)-12 in parallel to C57BL/6 wild type mice as models for murine cryptosporidiosis. Our results identified IFN-gamma as the key cytokine in the innate as well as adaptive immunity during primary and also challenge C. parvum infection. Furthermore, both Th1 and Th2 cytokines appear to contribute to the resolution of a primary infection, the former being dominant over the latter. Dramatic changes in the expression of cytokine genes were seen in the ileum (the site of infection) but not in the mesenteric lymph nodes and spleen. During re-challenge, a significant increase of IFN-gamma was recorded in IL-12 deficient mice (IL-12KO). Additionally, we present data suggesting a contribution of IL-18 in resistance of C. parvum infection even in the absence of IFN-gamma. Anti-IL-18 antibody treatment led to increased susceptibility to infection in both strains of immunodeficient mice. Besides its function in inducing IFN-gamma in IL-12 knock out mice, IL-18 appears to be involved in the regulation of the Th1/Th2 responses in C. parvum. Neutralization resulted in a cytokine imbalance with up regulation of systemic (spleen) Th2 cytokine genes, notably IL-4 and IL-13. These data demonstrate that susceptibility or resistance to C. parvum infection depends on a delicate balance between the production of Th1 cytokines, needed to control parasite growth, and Th2 cytokines, to limit pathology.

A Hospital-Based Serological Survey of Cryptosporidiosis in the Republic of Korea

The seroprevalence of cryptosporidiosis was examined using patients' sera collected from hospitals located in 4 different areas of the Republic of Korea. ELISA was used to measure antibody titers against Cryptosporidium parvum antigens from a total of 2,394 serum samples, which were collected randomly from patients in local hospitals; 1) Chungbuk National University Hospital, 2) Konkuk University Hospital, 3) local hospitals in Chuncheon, Gangwon-do (province), 4) Jeonnam National University Hospital, from 2002 through 2003. Of the 2,394 samples assayed, 34%, 26%, and 56% were positive for C. parvum-specific IgG, IgM, and IgA antibodies, respectively. Positive IgG titers were most common in sera from Jeonnam National University Hospital, Gwangju, Jeollanam-do, and positive IgM titers were most common in sera from Chungbuk National University Hospital, Cheongju, Chuncheongbuk-do. The seropositivity was positively correlated with age for both the IgG and IgA antibodies but was negatively correlated with age for the IgM antibodies. Western blotting revealed that 92%, 83%, and 77% of sera positive for IgG, IgM, and IgA ELISA reacted with 27-kDa antigens, respectively. These results suggested that infection with Cryptosporidium in hospital patients occurs more commonly than previously reported in the Republic of Korea.