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In the serum of patients with typhoid fever counterimmunoelectrophoretic techniques were used for the detection of antibodies to Salmonella "O" antigen. Lipopolysacharides (LPS) obtained with phenol and water from Salmonella typhi (antigens 0, 9 and 12) were used. Positive results were obtained in those patients with typhoid fever (20). The lower and higher titration levels were 1:8 and 1:32 respectively; the geometric mean was 1:16. The variation coefficient during the intra assay tests was 0.19, and remained stable throughout the inter-assay tests. Reproducibility, as well as a rapid technique, make this test a valuable tool for the serologic diagnosis of typhoid fever.

We report two cases of meningitis due to Haemophilus influenzae type b resistant to ampicillin and chloramphenicol. In one child the meningitis was preceded by pneumonia and pleural effusion. Both children responded to treatment with cefotaxime.

No clinical, cytochemical nor electroencephalographic standards of behavior, specific for each etiology were found in a series of 67 cases of viral infection of the nervous system; however, the severeness was greater in cases of infectious mononucleosis with encephalic involvement and in cases caused by Coxsackie B5 possibly because these appeared in younger patients. The group with greater percentage of definitive motor and intellectual sequelae was found in cases with infectious mononucleosis and ECHO. Cases due to herpes simplex were not more severe during the acute stage, but followed a course with an important percentage of definitive sequelae. Meningoencephalitides from parotiditis were milder, and only in one case did they show permanent motor sequelae.

A study was made of 29 cases of single ventricle confirmed by autopsy, hemodynamic study, or both. It must be emphasized that the term single ventricle excludes whatever malformation which shows traces of an intraventricular septum. Thus conceived, the malformation has been seen to have different clinical courses, which only permit partial diagnosis that may suggest the possibility of "single ventricle". In live patients this can only be diagnosed with specialized studies. In outline, there exist 4 types of clinical hemodynamic behavior: 1) The type with marked increase of pulmonary flow, in which the single cavity vascular systems, pulmonary and aortic, had similar pressures. This type behaves, in a certain way, like large interventricular communications. 2) The type which behaves hemodynamically like a large hypertensive communication with delayed cyanosis of rapid evolution and with few manifestations of heart failure. 3) The third type also has pulmonary hypertension with delayed cyanosis. This differs from the preceeding in that there is a preferential flow in such a way that the venous blood proceeding from the right atrium empties into the aorta and the arterial blood from the left atrium empties into the pulmonary artery. 4) The fourth type is characterized by rapid cyanosis and from the anatomical point of view has stenosis or atresia of the pulmonary artery. An analysis was made of the varieties which within these four classes actually ocurred or cases which were present as theoretical possibilities: single ventricle with crossed great arteries; single ventricle with transposition of the great arteries; single ventricle with partial distortion of the great arteries; single ventricle with common trunc. A detailed analysis was made of the clinical, hemodynamic, electrocardiographic, and radiological manifestations which are seen in these combinations and an anatomic-embriologic classification is proposed on the basis of the systematization of the 29 cases of the present study. Finally brief considerations are made of the operability of those cases of single ventricle according to their anatomic variety.

E. histolytica tissue invasion induces IgG and IgM and probably IgA serum antibody formation of different types in the intestinal mucosa. 21 children with intestinal invasive amebiasis were studied. Samples were taken from peripheral blood and stools during diagnostic studies and three weeks later. Contraimmunoelectrophoretic antibody determinations and indirect hemagglutination tests IH were made in an attempt to demonstrate its true nature. During the acute phase (first sample), results showed antibodies against amoeba in stools by CIE in 57 per cent and by IH in 80 per cent; in serum, results were 38 and 76 per cent respectively. In the second sample and three weeks after diagnosis was established a decrease in the number of patients with coproantibodies against amoeba was observed and the number of patients with serum antibodies increased. We are also providing evidence that supports the IgG and IgA nature of coproantibodies against amoeba. These results suggest the presence of a local immunological reaction in invasive amebiasis.

Furazolidone has normally been administered as a non-absorbable antimicrobial agent for use in gastrointestinal infections. However, in India and Mexico it has been used successfully for the treatment of typhoid fever. We measured concentrations of furazolidone by high performance liquid chromatography (HPLC) in several biological fluids, after a single oral dose (5 mg/kg). Six healthy adult volunteers and seven children with typhoid fever and ten children with purulent meningitis were studied. In adults the peak serum concentration was less than or equal to 0.84 mg/l and less than or equal to 4.78% of the ingested dose was excreted in the urine. In the children concentrations were similar to those found in volunteers. The cerebrospinal fluid/serum ratio ranged from 1.02 to 5.95 in the meningitis patients. HPLC is a rapid and sensitive method for the quantitation of furazolidone in biological fluids. The minimum detectable concentration was 0.05 mg/l, with a precision of 6% from peak area and an average recovery of 98%.

During the period October to December 1979, rotaviruses were obtained from infants and young children hospitalized with acute gastroenteritis in Mexico City and were compared by analysis of the migration of their double-stranded ribonucleic acid (RNA) genome segments in gel electrophoresis. Comparison of the results of this analysis and of those of similar studies carried out in 1977 and 1978 showed that the two rotavirus electropherotypes designated 2s and 21 have been continuously present and that the proportion in which these two types have been found in hospitalized patients has varied greatly year to year. The RNAs from rotaviruses 2s and 21 differed in the electrophoretic migraton of at least eight genome segments. However, RNAs from virus assigned to the same electrophoreotypes were not necessarily identical: on the basis of small but significant differences in the migration of segment 7, 8, or 9, isolates of types 2s and 21 could be assigned to two and three different subtypes, respectively. Human rotaviruses obtained in a distant geographical region, Santiago, Chile, in July 1979 had RNA electrophoretic patterns similar to that of electropherotype 21 but different from it in the migration of one or two of the larger RNA segments.

An area of high endemicity for hepatitis B and delta antigen was identified in the southern border of Mexico (Chiapas). The study included individuals from mexican communities and guatemalan refugee camps. 91.1% of the subjects were positive to anti-HBcAg antibodies. The frequency of asymptomatic carriers of HBsAg went from 4.2% in mexican communities to 17.3% in guatemalan refugee camps, the percentage was higher in households with six or more persons per room (14.0 per 100 individuals). The prevalence of e antigen in subjects positive to HBsAg was higher among guatemalan refugees (35.3%) than among mexicans (7.7%). A refugee camp, Benemerito de las Americas, showed 65.6% positives to anti-HBcAg antibodies and 39.0% asymptomatic HBsAg carriers, 41.7% of these were positive to HBeAg. Antidelta antibodies were present in 50 of 119 subjects positive to HBsAg. The mechanism of transmission was mainly horizontal since most of the infected children in each household corresponded to the oldest offspring. Our data were similar to those observed in the amazonian region of Brazil, Southeast Asia and tropical Africa.

This paper shows the results of a study of acute diarrhoea (AD) in 137 rural communities in Mexico. We studied 51 communities with 1000 inhabitants or less, 45 communities with 1001 to 5000 inhabitants and, 41 with 5001 to 15000 inhabitants. All in all we observed 4,796.9 persons year during a period comprised from March 1982 to February 1983. In communities with more than 5000 inhabitants there occurred 0.85 episodes of AD per person-year, whereas in the smaller ones the incidence was only 0.58 episodes per person-year p less than 0.01). In small communities the frequency was higher in families with poor water supply and inadequate excreta disposal, whereas in large communities the frequency was not affected by such services. In 95.6 percent of the cases the episodes were self-limited within the first 14 days. There were seven deaths, five occurring in children under one year of age, six in children living in small communities and, five associated with dehydration. These results suggest that the size of the community constitutes a risk factor for AD in rural areas, which deserves to be explored in further studies. The lethality observed in small communities stresses the need of programs for better treatment of this frequent disease.

The study included 205 children with measles seen after an epidemic outbreak in Distrito Federal during the first six months of 1976. 65.8% of the cases had not been given specific immunization and out of the 70 vaccinated cases (34.2%), one half of them were under one year old and were not given re-enforcement afterwards. The clinical picture suffered no changes in vaccinated children, 40% of infants showed initial exanthema on chest and abdomen with centrifugal distribution and in 41.5% of them, diarrhea appeared during the prodromal period. The most outstanding elements of this epidemic outbreak were the high number of sensible cases and the high percentage of children vaccinated before the age of one year and who were not later given re-vaccination. Indequate handling of the vaccine or combination of vaccine withe gammaglobulin used in 1969 and 1970, are also mentioned as a possibility to explain failures of the vaccine in ths group of well vaccinated children.

Through Scott's tubes, intraventricular administration of amynoglucoside antibiotics was given to two groups of patients: a) ten children with purulent meningitis and ventricular ependymitis due to gram - negative germs without malformation of the central nervous system (CNS) and b) sixteen children with ventricular ependymitis and malformation of the CNS. The duration of treatment was three weeks and no deaths issued in the first group. In the second group, there were four therapeutic failures related with the existence of encephalodysplasia or intraventricular wailing. The results described are very encouraging and allow to foresee a marked drop in the lethality of ventricular ependymitis.

Human rotaviruses, which are placed into two groups according to their ribonucleic acid patterns obtained by gel electrophoresis, were characterized both by polypeptide components from purified virions and by polypeptides translated from their denatured ribonucleic acids in rabbit reticulocyte lysates. Viruses assigned to different groups differed in the electrophoretic migration of the second largest of the polypeptides which compose the inner shell; polypeptides that had been synthetized in vitro from ribonucleic acid from each group showed this same difference, thus indicating that this is due to the genomic composition. This study suggests that there are differences in the third largest polypeptide of the inner shell and also in the three smaller polypeptides composing the outer shell. We also demonstrated that there are differences in genomic and polypeptide compositions between simian (SA11) and calf (Nebraska calf diarrhea virus) rotaviruses grown in tissue culture and human rotaviruses.

Hearing loss was studied prospectively using auditory brainstem potentials in 34 children with Hemophilus influenzae meningitis treated with chloramphenicol and in 36 children with purulent meningitis caused by microorganisms other than H influenzae treated with ampicillin. Our results indicate that high doses of ampicillin are not associated with permanent hearing loss. Moreover, no statistically significant difference was found in the incidence of hearing loss following H influenzae meningitis and that following meningitis caused by other microorganisms, either during the acute phase or in the convalescent period. Neurological damage, when present, was probably located in the inner ear or in the auditory nerve. Finally, early hearing loss in purulent meningitis does not always constitute an irreversible lesion.

The various classes of immunoglobulins with antibody function against E. histolytica were studied in 8 children with amebic liver abscess and in 7 with acute intestinal amebiasis. The predominant fraction was IgG in 7 patients from the first group and in 1 from the second; this suggests a secondary type humoral immune response which implies a previous experience with E. histolytica antigens. A definitive predominance of IgM was shown in a patient with amebic liver abscess, the same as in primary humoral immune response. Humoral antibodies did not develop in the remaining 6 patients with acute intestinal amebiasis. The disparateness of the humoral immune response found in these cases make it difficult to speculate on the role of immunoglobulins in the pathogenesis or in immunologic protection in amebiasis. Possibly, the most important is the participation of cellular immunity.

During a 22-month period, 595 children with diarrhea and 210 age-matched controls attending clinics in Houston (367 children) and Mexico (438) were prospectively evaluated for enteric pathogens. Enteropathogens associated with disease were Shigella (18%), rotavirus (14%), Salmonella (9%), toxigenic Escherichia coli (6%), and others (12%), including 14 Proteus isolates that caused rounding of adrenal cells. Enteropathogens were isolated from a greater (P less than 0.001) number of children with diarrhea (59%) than from asymptomatic controls (6%). Paired sera tested for antibody to heat-labile toxin of E. coli rarely demonstrated a fourfold rise during episodes of diarrhea. This study demonstrates: (1) more striking illness in children from Mexico; (2) more common occurrence of Shigella in Houston, and of rotavirus and Salmonella in Mexico; (3) lack of seasonal occurrence of rotavirus isolation in either population and a summertime occurrence of Shigella in Houston; (4) lack of toxigenic E. coli isolation in endemic diarrhea of either population; and (5) a significant (P less than 0.001) age-related acquisition of E. coli LT antibodies.

Concentrations of lactate and pH were determined in the CSF of 20 normal children, 36 with viral meningitis, 16 with purulent meningitis and six with tuberculous meningitis. No differences were found between normal cases and those with viral meningitis. In patients with purulent meningitis concentration of lactate was above 30 mg/100 ml and pH below 7.3. Both determinations allowed differentiation between viral meningitis and purulent meningitis after 48 hr of treatment with antibiotics in 80% of the cases.