Secreted products of Fasciola hepatica inhibit the induction of T cell responses that mediate allergy.

There is evidence from epidemiology studies of a negative association between infection with helminth parasites and the development of allergy and asthma. Here, we demonstrate that the excretory/secretory products of the helminth Fasciola hepatica (FHES) protected mice against ovalbumin (OVA)-induced allergic asthma when administered at time of allergen sensitization. FHES reduced the accumulation of mucus, eosinophils and lymphocytes into the airways of allergen-challenged mice. Furthermore, FHES treatment suppressed Th2 responses in the airways. Interestingly, systemic administration of FHES at allergen challenge had no effect on airway inflammation, demonstrating that alum-induced Th2 response is set following initial allergen sensitization. Our findings highlight the immunomodulatory potential of molecules secreted by F. hepatica.

A critical role for the TLR signaling adapter Mal in alveolar macrophage-mediated protection against Bordetella pertussis.

Bordetella pertussis causes whooping cough, an infectious disease of the respiratory tract that is re-emerging despite high vaccine coverage. Here we examined the role of Toll-like receptor (TLR) adapter protein Mal in the control of B. pertussis infection in the lungs. We found that B. pertussis bacterial load in the lungs of Mal-defective (Mal(-/-)) mice exceeded that of wild-type (WT) mice by up to 100-fold and bacteria disseminated to the liver in Mal(-/-) mice and 50% of these mice died from the infection. Macrophages from Mal(-/-) mice were defective in an early burst of pro-inflammatory cytokine production and in their ability to kill or constrain intracellular growth of B. pertussis. Importantly, the B. pertussis bacterial load in the lungs inversely correlated with the number of alveolar macrophages. Despite the maintenance and expansion of other cell populations, alveolar macrophages were completely depleted from the lungs of infected Mal(-/-) mice, but not from infected WT mice. Our findings define for the first time a role for a microbial pattern-recognition pathway in the survival of alveolar macrophages and uncover a mechanism of macrophage-mediated immunity to B. pertussis in which Mal controls intracellular survival and dissemination of bacteria from the lungs.

[Training for diagnosis of intestinal parasitic diseases in the national laboratory system of Cuba]. / Adiestramiento en el diagnóstico de las parasitosis intestinales en la red de laboratorios de Cuba.

A national training project in the diagnosis of intestinal parasites was conducted in 1997. An initial national course was followed respectively by courses in the Central, Eastern, and Western Provinces. Our results showed that Cryptosporidium parvum, Cyclospora cayetanensis, and leukocytes showed a significantly lower percentage of errors after the training than before (p < 0.01). The same occurred with Entamoeba histolytica/E. dispar and Chilomastix mesnilii (p < 0.05). Among the helminths, Taenia spp., Fasciola hepatica, and hookworm showed significantly fewer errors after the training (p < 0.01). In the other specimens, few mistakes were found both at the beginning and after the training, and the percentage of errors did not change (p > 0.05). Furthermore, when comparing scores before and after training, a significant increase in median scores appeared in the Central Provinces (p < 0.05), Western Provinces (p < 0.01), and in the entire series (p < 0.01). The results showed the effectiveness of this intervention; these periodic mandatory training courses should be developed together with national programs for quality assessment in Parasitology.

Kinetics of antibody-based antigen detection in serum and faeces of sheep experimentally infected with Fasciola hepatica.

The monoclonal antibody ES78 was used in a sandwich immunosorbent assay (Sandwich ELISA) for the detection of antigens in sera and faeces in the course of Fasciola hepatica infection in 10 experimentally infected sheep. All infected sheep had circulating antigens in the first week post-infection (WPI). Antigenemia was detectable until WPI 3 in four infected sheep, WPI 4 in five infected sheep and in only one sheep by WPI 5. The detection of coproantigens (Fa(g)) was possible in five infected sheep at WPI-4, in four sheep at WPI-5 and in one sheep only at WPI-6. This technique was compared to an indirect ELISA for the detection of antibodies using excretory secretory antigens of F. hepatica. A significant correlation was found between Fa(g) and egg output and also with adult worm numbers. Our method demonstrated that the diagnosis of active fasciolosis in sheep is possible during all periods of infection.

Longitudinal study of giardiasis in three day care centres of Havana City.

The prevalence, incidence and reinfection of giardiasis were studied in 365 children attending three day care centres (DCCs) in Havana City. Three stool samples were obtained from each child every 6 months during an 18-month period. We identified three distinct groups of children according to their patterns of infection. In the largest group (51%) children were never found infected. In the second group, they were found infected once or twice during the study period, and in the third and the smallest group (9%) they were found infected in most or all the study periods. This last group seems to be children 'predisposed' to Giardia lamblia infection. The prevalence of giardiasis (20%) remained almost constant throughout the study period. The incidence declined from 16 to 11%, and reinfection increased from 36 to 49%. All the children had normal nutritional status and the only clinical manifestation that correlated strongly with the frequency of cross-sectional surveys positive to Giardia was the number of diarrhoeal episodes recorded during the last 6 months of the study period. Further studies will be necessary to ascertain the causes that determine the 'predisposition' to giardiasis in children.

Kinetics of antibody-based antigen detection in serum and faeces of sheep experimentally infected with Fasciola hepatica.

The monoclonal antibody ES78 was used in a sandwich immunosorbent assay (Sandwich ELISA) for the detection of antigens in sera and faeces in the course of Fasciola hepatica infection in 10 experimentally infected sheep. All infected sheep had circulating antigens in the first week post-infection (WPI). Antigenemia was detectable until WPI 3 in four infected sheep, WPI 4 in five infected sheep and in only one sheep by WPI 5. The detection of coproantigens (Fag) was possible in five infected sheep at WPI-4, in four sheep at WPI-5 and in one sheep only at WPI-6. This technique was compared to an indirect ELISA for the detection of antibodies using excretory secretory antigens of F. hepatica. A significant correlation was found between Fag and egg output and also with adult worm numbers. Our method demonstrated that the diagnosis of active fasciolosis in sheep is possible during all periods of infection.

[Knowledge, opinions, and practices regarding Aedes aegypti]. / Conocimientos, opiniones y prácticas sobre Aedes aegypti.

The active participation of the community is indispensable for reducing Aedes aegypti mosquito populations so causes leading to their growth, actions taken, effects on the health and the people in charge of controlling such mosquitoes are all dealt with in this paper. 210 persons were interviewed from June 25 to 27, 1997. The causes of the growth of the mosquito population were: excessive garbage (59%), dirty waters (58%), open water reservoirs (50%) and lack of fumigation (21%). 40% of interviewed people did not know that these vectors can breed even in clean waters. They mentioned some effects on the health due to the mosquito bites. 51% said that mosquitoes should be jointly controlled by the State and the community but 35% believed that the State should be the sole responsible for this task. These opinions may determine that steps are not properly taken to avoid proliferation of vector and that the activities of the anti-vector program are not really understood since they do not meet the expectations.

Dynamics of antigenemia and coproantigens during a human Fasciola hepatica outbreak.

In the present study the dynamics of antigenemia and coproantigens were studied in patients with Fasciola hepatica infection during an outbreak occurring in La Palma, Pinar del Río, in the West Province of Cuba. Stool and serum samples were collected from 67 patients and 40 healthy subjects. Stool samples were studied by a simple gravity sedimentation technique and an ES78 sandwich enzyme-linked immunosorbent assay (ELISA) for observation of eggs and detection of parasite coproantigens, respectively. Serum samples were also studied by the ES78 sandwich ELISA and an indirect ELISA to detect circulating antigens and antibodies, respectively. At the beginning of the study, 8 of 67 patients had patent infections and 59 had prepatent infections, which was determined by the recent consumption of lettuce contaminated with metacercariae of F. hepatica, the presence of clinical symptoms, and the absence of Fasciola eggs in their stools. Patients with prepatent infections were monitored by all techniques until patency. Circulating antigens were not detected in patients with patent infections. However, coproantigens were clearly detected in all patients with patent infections. On the other hand, 28.8% of patients with prepatent infections tested positive for circulating antigens and 81.4% tested positive for coproantigens in the first stool sample studied. Only two other coproantigen determinations were necessary to diagnose 93.2% of the patients. While circulating antigen levels diminished in all patients during the infection, coproantigen levels increased. The present study demonstrates that the ES78 sandwich ELISA is a better tool than parasitological examination for diagnosis of active early infection, since by the combination of the circulating-antigen detection assay and the coproantigen detection assay 91% of patients were able to be diagnosed at the beginning of the study. In contrast, a coprologic analysis repeated over several weeks was necessary to diagnose 100% of the patients.

Specific cellular and humoral immune response in Balb/c mice immunised with an expression genomic library of Trypanosoma cruzi.

An expression genomic library of Trypanosoma cruzi (T. cruzi) constructed using pcDNA3 plasmid was used for the immunisation (25 micrograms) of Balb/c mice. Expression of T. cruzi antigens in the muscle of inoculated mice was detected by indirect immunofluorescence 7 days after immunisation. Specific IgG antibodies were significatively increased (P < 0.05) in animals that were reimmunized with 50 micrograms of the genomic library. An antigen specific lymphoproliferative response was detected in one animal of the group inoculated with one dose of the library.

Partial characterization of the epitope on excretory-secretory products of Fasciola hepatica recognized by monoclonal antibody ES78.

This report contains a partial characterization of the epitope recognized by monoclonal antibody (MAb) ES78 produced against excretory-secretory (ES) antigens of Fasciola hepatica. ES78 is currently used for the detection of ES antigens in serum and stool samples of cattle and humans with fasciolosis, using a highly sensitive and specific sandwich enzyme-linked immunosorbent assay (ELISA). The epitope was characterized by periodate oxidation, alkaline borohydride reduction, trichloroacetic acid precipitation, beta-mercaptoethanol treatment, and enzymatic proteolysis. These results, together with those of the 2-site ELISA, lectin immunoassays, and beta-galactosidase digestion, showed that MAb ES78 reacts with a partly protein/partly carbohydrate antigenic determinant that is found on several ES molecules of adult specimens of F. hepatica and contains at least 1 disulfide bond and beta-galactose probably as galactose-beta(1-3)-N-acetylgalactosamine disaccharide.

Detection of Fasciola hepatica antigen in cattle faeces by a monoclonal antibody-based sandwich immunoassay.

A monoclonal antibody-based sandwich immunoassay (mAb sandwich ELISA) was developed for the detection of Fasciola hepatica antigen in the faeces of cattle. The assay was applied to samples from 100 cattle infected with F hepatica, 56 animals with parasitologically proven infections of other parasites and 100 uninfected animals. F hepatica antigen was detected in all the faecal samples from animals with fasciolosis, but none of the samples from the uninfected animals or from those with other parasitic infections had significant levels of F hepatica antigens. The results indicate that the mAb sandwich ELISA is a rapid, simple and useful method for the diagnosis of active F hepatica infection in cattle.

A longitudinal study of enterobiasis in three day care centers of Havana City.

Pinworm infection was prospectively studied during one year in 469 children attending three day care centers. Each child was examined at six months intervals using up to three perianal swabs with adhesive tape. Those found infected were treated with mebendazole. At the beginning of the study we found a prevalence of 28% that dropped to 13% and 12% in the following study periods. The reinfection rate was twice the incidence rate in both study periods. We also found a small percentage (10%) of the children reinfected in most or all study periods. There was a high correlation between reinfection and perianal itching. Our results add further knowledge to the epidemiology of intestinal parasites in day care centers.

[The knowledge of the population about cholera]. / Conocimientos de la población sobre el cólera.

In order to determine the impact of the educational campaign about cholera on the knowledge and believes of the population, a survey was made in 1993 among 1324 persons from 14 provinces and from Isla de la Juventud special municipality. 85% were 20-59 years old and 89% had an secondary basic or higher educational level. 69% had the minimum knowledge to face the disease, 90% would see a doctor if they had and suspicion, 72% knew that diarrhea is the main symptom of cholera, 54% new how it is transmitted 89% thought that they may be infected by drinking water, 54% understood the importance of giving liquids to the sick subject, and 78% realized the significance of washing their hands before eating anf cooking. It is concluded that even though our population has a general knowledge about the disease, due to the fact that our country is located in an endemic zone, health education must be reinforced, specifically those aspects connected with the communication and with the increase of liquids administration to the patients.

Sandwich enzyme-linked immunosorbent assay for detection of excretory secretory antigens in humans with fascioliasis.

A sandwich enzyme-linked immunosorbent assay has been developed for the detection of Fasciola hepatica excretory secretory (ES) antigens in stool specimens of infected humans. The assay uses antibodies against F. hepatica ES antigens. A monoclonal antibody (ES78, mouse immunoglobulin G2a) was used to capture ES antigens, and a rabbit polyclonal antibody, peroxidase conjugate, was used to identify ES antigens. Thirteen of 14 patients with parasitological evidence of fascioliasis had a detectable concentration of ES antigens (more than 15 ng/ml). None of the stool specimens from controls and from patients with parasites other than F. hepatica showed a positive reaction, suggesting the absence of cross-reactions in this assay. When the 14 patients were retested 2 months after treatment, all of the specimens from the 11 parasitologically cured patients were negative by the antigen detection assay while the specimens from the 3 patients with persisting F. hepatica eggs in their stools remained positive.

[Study of the seroprevalence of toxocariasis in an infantile population in the City of Havana]. / Estudio de seroprevalencia de toxocariasis en una población infantil de Ciudad de La Habana.

A serological study to detect antibodies to Toxocara canis in a group of 156 healthy children from City of Havana is reported for the first time in Cuba. An ELISA method was employed using excretion/secretion antigens obtained in our laboratory. Data on epidemiological factors surveyed in this group are presented. Positivity percentage was of 5.2%. Results are discussed.

Inhibition of human monocyte function by prophylactic doses of chloroquine.

The effect of prophylactic doses of chloroquine on the phagocytic function of human monocytes was studied in young healthy male volunteers. They received placebo, 300, or 600 mg of chloroquine base/week for six weeks. In each subject, the phagocytic function was tested before and at the end of the chloroquine intake period. In the 600-mg chloroquine group, it was also tested six weeks after receiving the last dose. Chloroquine at both doses inhibited the phagocytosis of IgG-coated sheep red blood cells and of zymosan particles. The effect was more pronounced with the 600 mg dose of chloroquine. The phagocytic activity returned to normal values six weeks after the end of treatment.