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Due to the importance of cysticercosis in Mexico and Latin America and to the fact that in the last years another mechanism of infection for this disease has been proposed, i.e. through postoncospheres and immunosuppression of the host, we have considered relevant to perform the present work, which consisted in assessing the immune response induced by dexamethasone as well as that produced by parasites in pigs infected with T. solium eggs, or postoncosphere-infected, and in postoncosphere-infected and dexamethasone-treated animals. We used 10 recently weaned pigs, three were used as controls, two of them without the drug and one with it; two were infected with T. solium eggs; five with postoncospheres receiving also dexamethasone three of them. We evaluated the humoral response against parasite antigen using indirect haemagglutination (IH) and ELISA methods. Results of the immune humoral response revealed titres of up to 1:128 in T. solium eggs infected animals, of 1:16 in postoncosphere infected animals, and of 1:32 towards the end of the experiment in postoncosphere plus dexamethasone animals. Absorbance titres with ELISA confirmed these findings. Data obtained by IH show that the antibody titres of the pigs challenged with postoncospheres and postoncospheres plus dexamethasone are positive as compared to the titres obtained in the pigs infected with T. solium eggs. Results from the ELISA confirmed this finding, since, from weeks 14 to 17, the pigs became positive, behaving as those pigs that developed cysticercosis. This is relevant as it indicates that the antiposcosphere antibodies recognized antigens of T. solium larvae.

An analytic relationship between positivity of the indirect immunofluorescent test (IIFT) for toxoplasmosis and clinical findings in a population of 328 children with cerebral infantile palsy (CIP) was performed. Children were distributed by age in one of four groups: I (0-2 years); II (3-6 years); III (7-12 years) and IV (13-18 years). One control group of 168 children with no PCI clinical findings was included. 125 sera were positive at 1:64 dilutions. The study of the binomial mother-child of 40 cases rendered 26 mothers with significant titer values. The majority of positive mothers to IIFT correlated with the youngest children (Groups I, II and III), mainly with group I (70.0%), which showed the highest titer ranges. Correlation between positive IIFT and clinical features was as high as 100.0%.

In the last years Cyclospora sp. has been increasingly associated to human intestinal diseases. The first studies have been reported to this parasite as a Cyanobacterium-like body, large Cryptosporidium or coccidian-like body. The ultrastructural characteristic and the "in vitro" sporulation have revealed the existence of oocyst constituted for two sporocysts with two sporozoites per sporocyst. This evidence has allowed its classification as a coccidian within the genus Cyclospora and its designation as a new pathogen species in humans, Cyclospora cayetanensis. Recently phylogenetic analysis based on rDNA sequences suggested that Cyclospora sp. was closely related to the Eimeria genus. The identification, morphological characteristics, clinical evaluation and chemotherapy of the human intestinal disease associated to Cyclospora sp. are commented in the present paper.

We report 29 new localities with Triatominae in the Republic of México; these Triatominae belong to 8 different species. Infection by Trypanosoma cruzi in the majority of these localities with high rates of positivity was found. Biological observations concerning the collected Triatominae are given. The necessity of continued work in relation to geographical distribution, ecology, frequency of infection by T. cruzy, and the role played by Triatominae of the Republic of México in the transmission of the infection to the man is stressed.

It was determined the presence of posoncospheres in muscular tissues in 20 natural cysticercotic pigs and in 20 pigs apparently free of Taenia solium metacestodes. Ten differents anatomical regions were dissected, giving 400 samples in total. The animals were slaughtered in Ecatepec, Mexico State, Mexico. The samples were kept in bottles with saline and were processed in the Laboratorio de Biología de Parásitos, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM); cysticercus were counted and later on the resulting muscular mass was grinded and observations were made in the sediment, for posoncospheres search. Mann-Whitney statistical method revealed meaningful differences between postoncospheres in cysticercotic pigs and not apparently cysticercotic pigs. The Linear Correlation Analysis showed no relation between cysticercus quantity and postoncospheres quantity in the same samples. Postoncospheres were found in cysticercotic animals and in those apparently free of cysticercus, in the last group the quantity was bigger.

Very few uncertain and not trustworthy reports about the frequency of intestinal helminthiases found in humans have been made in México. However, with the few trustful studies carried out from 1981 to 1992, it is possible in México to verify that ascariasis, trichuriasis, hookworm infection and hymenolepiasis are present with significant percentages of infected people 11.2%, 1.7%, 0.15% and 1.8%, respectively. With the information obtained from the researches analyzed in this article, one can conclude that human infections by intestinal helminths in México, at the present time are almost as frequent as in past decades. Without any doubt, this occurs because still remain the factors that contribute to the persistence and spreading of the intestinal helminths, such as fecalism, poor hygienic and alimentary habits within deficient environmental sanitary conditions.

The reports about the frequency of intestinal protozooses found in humans who live in different localities of the Mexican Republic, are in general uncertain and not trustworthy, possibly because very few and poor epidemiological surveys have been undertaken in the country. However, with the few trustful studies carried out (1981 to 1991), it is possible in Mexico, to verify that amibiasis, giardiasis and criptosporidiosis are present with significant percentages of infection: 30.6, 22.3 and 39.3% respectively. With the summary of the researches analyzed in this article, one can conclude that human infections by intestinal protozoa in the Mexican Republic, at the present time, are almost as frequent as in past decades. This occurs because still remain the factors that contribute to the persistence and spreading of intestinal parasites, such as fecalism, poor hygienic and alimentary habits, within a deficient environmental sanitation.

An indirect hemagglutination test (IHAT) for toxoplasmosis and electrocardiogram (EKG) were performed to 11,161 apparently healthy inhabitants with negative IHAT for Chagas' disease, from 259 rural and periurban localities sited in the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country). The age of the 11,161 examined people ranged between 5 and 94 years, being 4,518 males and 6,643 females. The IHAT for toxoplasmosis was considered positive with titers > or = 1:16. This test resulted positive in 3,519 (31.1%) persons (30.8% in males and 32.0% in females). Positivity of the IHAT increased from 21.2%, in the youngest group (< 10 years) up to 46.9% in the oldest group (> or = 60 years). Different types of EKG alterations were observed in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. In both groups the percentages of altered EKG increased parallel with age. The overall difference of percentages of altered EKG in IHAT positive and IHAT negative persons has a statistical significance with p < 0.001. This study suggest the convenience to consider toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, because a possible Toxoplasma gondii infection may contribute to overincrease the magnitude of the impact of Trypanosoma cruzi in the generation of the quoted myocardiopathy.

To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy.

In August-December 1992, 500 diaphragm muscle samples taken at random from people who were autopsied at the Santiago Medico-Legal Service, were submitted to phototrichinoscopy to search for encysted larvae of Trichinella spiralis. For each sample seven small pieces were examined. Three hundred and eighty nine (77.8%) cadavers corresponded to males and one hundred and eleven (22.2%) to females. Ages ranged from 1 to 90 years. Ten (2.0%) of the individuals examined resulted positive, the higher frequencies corresponding to individuals over 20 years of age. The prevalence rate of T. spiralis infection found is rather similar to those detected in 1966-1967, 1972 and 1982, with percentages of 2.2, 3.4 and 2.8 respectively.

An ELISA-IgG test using a soluble extract of Trypanosoma cruzi antigen has been developed. One hundred and seventy eight sera (74 healthy people, 44 chagasic patients with positive xenodiagnosis and 60 with clinical symptoms), and 64 paper filter blood eluates (35 healthy people, 10 chagasic patients and 19 with clinical symptoms) were tested by ELISA-IgG and an indirect hemagglutination test. Both types of methods presented an overall average concordance of 98.3% and 100.0% with sera and filter paper blood eluates respectively. A cut off (average of optical density plus 3 standard deviations) of 0.365 and 0.379 for sera and eluates was found. The use of ELISA-IgG in Chagas' disease clinical diagnosis and seroepidemiological studies is discussed.

A thorough review of the medical literature is made regarding Chagas' disease in Mexico and elsewhere since 1939, when Trypanosoma cruzi was first reported in this country, until 1991. The location where human cases, non human reservoirs and vectors have been found and are pointed out by means of tables and charts. Comments are made regarding the results reported. The importance of increasing the studies of Chagas' disease in Mexican Republic is stressed.

Absorption experiments to determine the number of T. gondii tachyzoites to extract the anti-Toxoplasma antibodies present in the human serum were carried out. The antibodies titer from each serum (n = 4) was determined by means of the Sabin-Feldman test (dye test). Ten millions of tachyzoites were sufficient to absorb the antibodies from sera presenting titer 1:16, 1:64 and 1:256. On the other side, the absorption of a 1:512 positive serum with 10 x 10(6) T. gondii decreased the titer to 1:64 and the dye test became negative when using 50 x 10(6) tachyzoites.

Cryptosporidium sp. infections have been reported in different Chilean localities, both in healthy individuals and immunocompromised patients. Among the first, hospitalized and ambulatory children less than 3 years old are the age group more affected reaching frequencies from 3.1 up to 19.3%. In pre-school children, school children and adults the prevalence rates have been 1.1, 0.2 and 0.3% respectively. According to the epidemiological studies carried out, the routine laboratory diagnosis of this parasitosis should be emphasized in the parasitological stool examinations in children under 3 years of age, and selectively in the older ones.

Chagas' disease, produced by Trypanosoma cruzi and transmitted by hematophagous triatomine bugs, exists in the Western Hemisphere from the south-western United States to central Chile and Argentina. It exists in rural and periurban sections of the northern half of Chile, with a prevalence of 16.9%. Constant rural-urban migrations have contributed to its spreading to urban sections. In order to investigate the impact of these migrations on the population susceptible of being blood donors and the probable increasing of the risk of T. cruzi transmission by blood transfusion, epidemiological surveys were carried out in donors from 22 hospitals located in the northern half of Chile. By means of an indirect hemagglutination test for Chagas' disease 16,841 blood donors were examined, arising a 2.7% of positivity, percentage that permitted to estimate that 126,477 potential blood donors infected with T. cruzi should be in the urban sections studied. These facts strengthen the need that serology for Chagas' disease must be routinely performed in endemic regions of the country, to adopt or reinforce the pertinent preventive measures.

Within a 14-24 hours lapse after gynecological operative surgery, a 27-year-old woman eliminated with vomit two large taperworm pieces, measuring 3 and 2 meters respectively. At the laboratory they were identified as Taenia saginata strobila with immature, mature and gravid proglottids. The patient informed that she liked to eat raw beef. Treatment consisted in a single dose of praziquantel: 15 mg/kg body weight. Parasitological controls (two series of three fecal samples each), performed three months later, resulted negative for Taenia eggs.

Lambda-cyhalothrin (LCT) is a new broad-spectrum synthetic pyrethroid insecticide with efficient immediate and persistent activity against a great variety of arthropods harmful both to human and animal health and to vegetal production. In many countries this insecticide has been successfully used in the control of infectious diseases vectors, such as mosquitoes, triatomine bugs (transmitters of Trypanosoma cruzi, agent of Chagas' disease) and other arthropods. In order to test the immediate and persistent activity of LCT under laboratory conditions (27 degrees C and 75-80% humidity) on laboratory reared Triatoma infestans--the most resistant instar of this insect to the commonest insecticides used--a series of six experiments was performed in 1-year period. Previous to experiments, the interior surface (400 cm2) of 36 specially manufactured cardboard boxes was uniformly sprayed with 2 ml of the following substrates: 12 with 0.6% LCT suspension, 12 with 1.0% LCT suspension and 12 with water (controls). Twenty four hours, 30 - 90 - 150 - 270 and 360 days later, in two pairs of each six boxes, lots of 10 T. infestans IV nymphs were deposited inside of them. In each of the six experiments, daily observations of the conditions of the insects (unaffected, affected in terms of various grades of progressive uncoordination, or dead) after exposure to the insecticide were performed to end with the register of these conditions 96 hours later. Moreover, after 7 and 10 days of exposure in the immediate and persistent effect of LCT respectively a 100% of mortality was verified.(ABSTRACT TRUNCATED AT 250 WORDS)

During a study on prevalence of parasitic and viral serological markers in pregnant adolescents, a 17-year-old primipara from Polpaico, village near Santiago, gave birth to a normal male newborn in a Santiago hospital. As both of them presented positive an indirect hemagglutination test (IHAT) for Chagas' disease and the corresponding xenodiagnosis (XD), the infection in the infant was considered to be acquired through the placental route. According to recent epidemiological surveys Polpaico is an endemo-enzootic chagasic rural settlement, where 14.7% of dwellings were infested with Triatoma infestans, while triatominae, persons and domestic mammals were found infected with Trypanosoma cruzi. One month later the adolescent mother, her son and other 11 consanguineous members of the family were visited in their homes in order to submit each of them to a physical examination and to IHAT for Chagas' disease, and XD to those whose IHAT resulted positive. Thus, in 7 (53.8%) the IHAT was positive and in 4 (57.1%) out of these 7 presented positive the XD, results that as a whole yielded a household chagasic endemics.

A study for evaluation of the yielding of xenodiagnosis (XD) in 1,181 persons with a previous positive indirect hemagglutination test (IHAT) for Trypanosoma cruzi infection was carried out. The infection of these people was detected during epidemiological surveys performed in rural-periurban and urban sections of the endemo-enzootic area of Chagas' disease in Chile, which involves the first seven, out of the thirteen political-administrative regions of the country. The sex distribution was 75.0% females and 25.0% males, varying the ages between 2 and 80 years. According to individual and geographical possibilities each person was submitted to 1-8 XD, which consisted in cylindrical wooden boxes containing seven third instar nymphs, laboratory reared, of Triatoma infestans. The boxes, covered with a piece of tulle fixed with a rubber band were applied on the skin of the posterior side of the arm of the subject to be examined, held with a linen bracelet during 25-30 min. After the insects were fed the boxes were maintained in the laboratory at 27 degrees C and 85% relative environmental humidity. Posteriorly, all the nymphs of each box were examined at 30, 60 and 90 days after the application. A drop of abdominal content of each of them, homogenized with a drop of saline, was examined at the microscope looking for T. cruzi. XD resulted positive in 503 (42.6%) people. The positiveness of XD showed a trend of increasing according to the number of boxes used, from 11.4% with one to 51.6% with six. Under a practical point of view, the simultaneous application of four XD boxes seems to be advisable.(ABSTRACT TRUNCATED AT 250 WORDS)

Even though Toxoplasma gondii is an ubiquitous parasite that can effect most of human structures and organs, not all clinical manifestations suggestive of being produced by it are caused by this protozoon. For these reasons sera samples of patients suspected of having toxoplasmosis are sent to the laboratory for detecting specific antibodies which would facilitate the differential diagnosis. Thus, 716 sera from suspected patients, mainly from the Metropolitan Region of Chile, were sent to the Parasitology Laboratory of Chile University in order to carry out in them, specific serological tests for toxoplasmosis: indirect hemagglutination test (IHAT), Sabin Feldman reaction (SFT) and complement fixation test (CFT). Were considered positive: IHAT and/or SFT with titers > or = 1:16 and CFT with titer > or = 1:5. The pathologies for demanding these serological tests were obstetrical problems 210 (29.3%), congenital problems 193 (27.0%), ophthalmopathies 81 (11.3%), adenopathies 77 (10.8%), AIDS 67 (9.4%), myocardiopathies 46 (6.4%) and miscellaneous 42 (5.9%). The positivity found in these sera was higher in ophthalmopathies (61.7%), followed by obstetrical problems, miscellaneous problems, myocardiopathies and AIDS (50.7-52.4%), less frequent was the positivity in adenopathies (35.1%) and congenital problems (23.1%). In general, the 43.7% of positivity for toxoplasmosis found in these patients is higher than the 37.0% found in the general population. High titers of IHAT and SFT plus positive CFT was found in 13-fold higher proportion than in the general population.

Chagas' disease is endemo-enzootic in periurban and rural sections of the first seven (18 degrees 30'-34 degrees 36' South lat.), out of the thirteen political-administrative regions of Chile. Permanent inhabited localities situated at different altitudes over the sea level (OSL) are classified in: coastal settlement (0-1,499 m OSL), intermediate settlement (1,500-3,000 m OSL) and altiplano settlement (> 3,000 m OSL). A total of 1,558 dwellings and their occupants from regions I and II were surveyed in 1982-1984 for different epidemiological Trypanosoma cruzi infection parameters. Hence, 261 dwellings, 189 domestic mammals and 517 people (ages 5- > or = 60 years) from the Altiplano settlement were studied. The results obtained were: 4(1.5%) and 2(0.8%) of dwellings infested with Triatoma infestans, according to occupants information and by observation of direct evidences respectively; 8(4.2%) animals (1 dog, 4 goats and 3 sheep) with a positive hemagglutination test (IHAT) for Chagas' disease; 21 people (4.1%) with a positive IHAT; 4(19.0%) and 3(14.3%), out of the 21 IHAT positive individuals with all types of electrocardiogram (EKG) abnormalities and EKG abnormalities suggestive of a chagasic etiology respectively, whereas 65(13.1%) and 15(3.0%), out of the 496 IHAT negative ones presented the same kinds of EKG abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

The rural migration to urban centers occurred since the 40s in many Latin American countries, including Santiago the capital city of Chile, originated a growing belt of premises built with light poor material (the rests of previous rural habitations, mud, pieces of timber, plastic and cardboard for walls, and cane stalks and artificial clinkstones for roofs) giving raise to many types of slums. This situation facilitated the passive transport of the different instars, including eggs, of triatomine bugs. Due to the fact that in the 1959-1960 warm seasons, the Santiago province health institutions had received an increasing reported number of triatomine bugs (Triatoma infestans) in dwellings from different periurban, even urban and rural sections of the province, the central local health authorities with the advise of the University of Chile, Department of Parasitology decided to carry out an experimental program against these vectors of Chagas' disease. The program consisted basically in an spray and thorough application of liquid forms (emulsion, suspension, solution) of 1% lindane (average > or = 500 mg per 1 m2), depending on the material of the constructions, to all the surfaces of walls, ceilings, attics and peridomiciliary structures of all the infested dwellings in a sector and those located less than 100 m around. In order to reach triatomine bugs not affected, for different reasons, in the first spraying, a second application, identical to the first was performed to the total number of premises between 30 and 120 days later. Periodical evaluations were made, and positive dwellings found and neighboring ones were sprayed again. During insecticide applications adequate protection measures for spraying workers, inhabitants, domestic animals, household goods and food were adopted. All the steps of the program were accompanied by health education activities directed to individuals, families, school teachers and community institutions, tending to motivate the people to an active participation, as in the report of the presence or reappearing of triatomines in premises as in cooperating in the sprayings and improving the material conditions of their properties. Thus, in the period 1960-1972 the following goals were achieved: 1) Spraying twice with 1% lindane 32,708 dwellings located in 199 quarters from 26 periurban and rural sections. 2) Protection to 191,090 people against T. infestans bites and the eventual acquired chagasic infection. 3) Percentages of triatomines infested dwellings decreased from to 18.7 to 3.0 according to residents and from 3.0 to 0.3 according insects collection. At present, a significant proportion of the sprayed dwellings has been demolished and replaced by new constructions.(ABSTRACT TRUNCATED AT 400 WORDS)

Experiments using two sequential discontinuous sucrose gradients, performed with 12%, 18%, 21% and 24% solutions, for the isolation of Cryptosporidium sp. oocysts from human fecal samples were undertaken. The sucrose gradients were centrifuged at 4000 rpm during 20 min. at 10 degrees C or room temperature. After that, 3 bands were observed. Oocysts were recovered mainly from the second band (75.5% after the first gradient, and 44.4% in the next). The two sequential discontinuous sucrose gradients would permit an efficient isolation of Cryptosporidium sp. oocysts from human fecal samples.

In July 1989-July 1990 period, a coproparasitological study of 6,162 ambulatory patients from the northern section of Santiago, was undertaken. Out of the total number of the studied individual, 88.6% were children, (51.4% females and 48.6% males). The global frequency of infection by B. hominis was 30.4%. In relation to age. Blastocystis hominis was found in: 13.1% of the group of children (1 month-2 years); 34.1% of the pre-school children, 45.4% in the school-children and 43.0% in the adults. B. hominis was frequently detected in association with other parasites and/or commensals, and observed alone in the 6.0% of the studied patients.

Chile is a long and narrow country located in the south western coast of South America. Chagas' disease exists in the seven first (18 degrees 30'-34 degrees 36' South lat.) of the total of thirteen administrative regions of the country. In the 1982-1990 period a series of studies considering different epidemiological aspects of this parasitic zoonosis has been carried out with the following results: 5,601 rural of periurban dwellings were surveyed for the presence of Triatoma infestans (the most important and almost exclusive vector of Trypanosoma cruzi in Chile). 37.4% of the dwellings were infested according to the inhabitants and 29.4% were found infested according to the presence of tracks or insects captured. In 659 (17.2%) out of 3,822 T. infestans captured and examined T. cruzi was found in their abdominal contents. The most common sources of T. infestans feeding were mammals (89.0%), including man, and birds (9.5%). An indirect hemagglutination test (IHAT) for Chagas' disease, a very sensitive and specific reaction, was performed to 5,050 domestic mammals, resulting positive 7.9% of cats, 7.0% of dogs, 7.0% of goats, 4.9% of sheep and 4.1% of rabbits. 2,579 (16.9%) out of 15,418 persons were positive for the IAHT for Chagas' disease. The rates of infection were rather similar in males (17.5%) and females (16.2%) with an increase in infection rates in accordance with increase of age of individuals. The overall frequency of ECG abnormalities in positive IHAT persons was 18.7% against 8.8% in those with negative IHAT, whereas ECG abnormalities considered as suggestive of a chagasic etiology were 6.8% and 2.2% respectively. The esophageal motility in 311 persons with a positive IHAT and in 150 with a negative IHAT was found altered in 42.8% and 18.7% respectively. In the corresponding urban sectors of the 7 regions mentioned 2.7% of blood donors, 2.3% of delivering mothers, 2.6% of newborns and 0.6% of school children had positive IHAT. 646 chagasic women and 709 non-chagasic women in their reproductive span of life, and the products of the pregnancies that they had in a 6-year period were followed-up. No significant differences were found neither in the number nor in the evolution of pregnancies in both groups of mothers. Xenodiagnosis of children from chagasic mothers resulted positive in 6.3-8.9%, showing the transmission of T. cruzi by the placental route. Recently, 3 cases of congenital Chagas' disease of second generation have been demonstrated.(ABSTRACT TRUNCATED AT 400 WORDS)

An indirect hemagglutination test (IHAT) for trichinosis using a Melcher's antigen was evaluated and compared with a precipitin test (PT) and a bentonite flocculation test (BFT). One hundred and forty eight serum samples from patients from the whole country confirmed or suspected to have trichinosis by clinical or epidemiological evidences were studied: 117 (79.1%) samples resulted positive by IHAT, 138 (93.2%) by PT and 65 (43.9%) by BFT. Sixty three serum samples from patients with strong clinical suspect of trichinosis presented the PT and the BFT positive and were compared with the IHAT for sensitivity study. IHAT was positive in 60 (95.2%) serum samples. In order to determine the specificity of IHAT 25 serum samples from healthy volunteers and 124 serum samples from individuals with other parasitoses, such as cysticercosis (48), hydatidosis (45) and fascioliasis (31) were studied. The specificity, using a titre > or = 1:16 as a possible diagnostic value was 96%. The use of IHAT with RP and BFT in the diagnosis of human trichinosis is discussed.

Two variations of an indirect hemagglutination test (IHAT) and a complement fixation test (CFT) for the diagnosis of human cysticercosis were compared and evaluated. For the IHAT, a cysticerci crude total saline extract (SE) and a cysticerci lyophylized and delipidized veronal bicarbonate saline buffer (VBS) extract were used, comparing their diagnosis yieldings with that of a CFT in 57 confirmed cysticercosis patients: 45 serum samples and 32 cerebrospinal fluid (CSF). Sera and CSF from 29 patients with other neurological diseases and 25 sera from healthy volunteers were also compared. Both types of methods presented an overall average concordance of 91.5% and 97.0% with CSF and sera respectively. With respect to the sensitivity observed with CFT was 85.2% and 93.3% for CSF and sera, whereas that of IHAT was 96.9% in CSF and 97.8% in sera, when SE antigen was used; with the VBS antigen for IHAT 96.9% and 95.6% were detected in CSF and sera respectively. In order to determine the specificity of the IHAT, besides the study in healthy volunteers, in patients with other neurological diseases and in 156 serum samples from individuals with other parasitoses, such as hydatidosis (43), trichinosis (56), fascioliasis (31) and Chagas' disease (26) were also tested. A high reactivity with the hydatidosis group was found. The specificity, using a titre > or = 1:16 as a diagnostic value and without considering hydatidic sera was 99.4% for RHAI (SE), 100.0% for RHAI (VBS). The use of IHAT and CFT in diagnosis of human cysticercosis is discussed.

In pursuing the studies on the epidemiology of toxoplasmosis in Chile, a recent series of surveys have been undertaken in 1983-1990 in 4 urban and 22 periurban-rural localities from regions X, XI and XII of the country (39 degrees 38'-56 degrees 00' South lat.). An indirect hemagglutination test (IHAT) for toxoplasmosis was performed to 6,438 randomly selected apparently healthy persons. The age of the surveyed persons (2,779 males and 3,659 females) varied between 1 and 93 years. The number of examined persons represents a 0.61% of the total population of the three studied regions. IHAT titers of 1: > or = 16 were considered as positive. The general prevalence for positive IHAT was 46.3% (47.4% in men and 45.4% in women). Similarly to other regions, a higher proportion of positive reactors was detected in urban sections (49.0%) than in periurban-rural ones (40.3%). An increase of prevalence with age was also observed. Only 8 (0.12%) persons presented IHAT titers higher than 1:1000.

Various methods with either cellular or humoral basis employed in the diagnosis of human parasitoses are reviewed. Using different methods and techniques humoral antibodies have been increasingly detected. Recently antigen research is becoming important, either in the acute phase of infection or in the immunocompromised host.

In presecuting the investigations on the epidemiology of toxoplasmosis in Chile, a new series of serological surveys has been performed during 1982-1989 in 10 urban and 25 periurban-rural localities from the regions VII, VIII and IX of the country (34 degrees 41'-39 degrees 38' South lat.). In 9,758, randomly selected apparently healthy persons, and indirect hemagglutination test (IHAT) for toxoplasmosis was carried out. The age of these individuals (4,203 males and 5,555 females) varied between 4 and 84 years. The examined persons represent a 0.33% of the total population of the three studied regions. IHAT titers of 1: > or = 16 were regarded as positive. The global prevalence for positive IHAT was 45.5% (50.5% in men and 41.7% in women). A higher proportion of positive tests was observed in urban areas (47.0%) than in periurban-rural sections (33.3%). An increasing prevalence with age was also observed. Only 5 (0.05%) persons had IHAT titers higher than 1:1000.