Enfermedad de Chagas / Chagas disease

La enfermedad de Chagas es una antropozoonosis provocada por un protozoo flagelado el Trypanosoma cruzi, que se transmite a través de vectores hematófagos infectados. En nuestro país los vectores son Triatoma infestans y spinolai (vinchuca). Su reservorio es humano y alrededor de 150 especies de mamíferos. Se distribuye en toda América pero mayoritariamente en el Cono Sur, con al menos 12 millones de personas infectadas. Los mecanismos de transmisión son principalmente vectorial, transplacentario, transfusional, otras formas de contagio menos frecuentes son el trasplante de órganos, accidentes de laboratorio, transmisión oral y uso de jeringas contaminadas drogadictos). Esta enfermedad dependiendo de si afecta a personas inmunocompetentes presenta tres etapas: aguda, latente y crónica, afectando en forma variable a diversos órganos, principalmente corazón y el tubo digestivo. El compromiso cardíaco se caracteriza por dilatación progresiva y alteración del aparato exitoconductor provocando arritmias y bloqueos auriculoventriculares (AV). A nivel digestivo afecta principalmente al esófago y colon; ocasionando acalasia llevando a dilatación y alteración de la motilidad progresiva, cuyo síntoma clave es la disfagia que se asocia también a odinofagia y regurgitación. A nivel del colon, el Chagas provoca dilatación progresiva por denervación parasimpática intramural, llegando a formar el megacolon chagásico, el síntoma principal es la constipación. Los métodos diagnósticos son clínicos, imagenológicos y la detección de la infección parasitaria, ya sea a través de métodos directos o indirectos, dependiendo de la etapa de la infección. El tratamiento se basa en antiparasitarios principalmente el nifurtimox y benznidazol, ambos son tripanomicidas, con una efectividad de hasta el 76 por ciento dependiendo de la etapa en que se usa.

Chagas disease is an anthropozoonosis caused by the flagellate protozoan Trypanosoma cruzi. It is transmitted in our country by the infected haemophagic vectors Triatoma infestans and Triatoma spinolai. 150 mammal species and the human serve as reservoir of T. cruzi. Chagas disease is distributed throughout the Americas, mostly in the Southern Cone, with at least, 12 million of people infected. Transmission mechanisms are mainly vectorial, transplacentary and transfusional. Other less frequent sources of transmission are organ transplantation, laboratory accidents, oral ransmission and the sharing of contaminated needles among drug users. This disease, depending on the immune state of the affected subject, has three stages of development: acute, latent and chronic, involving several organs at different levels, mostly the heart and gastrointestinal tube. Heart involvement is characterized by progressive dilatation and alteration of the electrical conduction system causing arrhythmia and atrioventricular (AV) block. The digestive compromise affects mainly esophagus and colon. It causes achalasia of the esophagus which causes dilatation and alteration of the propulsive motility with dysphagia being associated to odinophagia and regurgitation. Chagas disease causes progresive colonic dilatation by intramural parasympathetic denervation, reaching Chagasic megacolon with constipation as the characteristic symptom. Diagnostic techniques are clinic, imagenologic, and the detection of the parasitary infection through direct or indirect methods, depending on the stage of the infection. Treatment is based on antiparasitic drugs, mainly Nifurtimox and Benznidazol, both are trypanomicides, with up to 76 percent efficacy, depending on the stage of the disease when they are used.

Tendencias en la etiología de la meningitis bacteriana aguda en niños chilenos período 1989-1998: impacto de la vacuna anti-H influenzae tipo b Hib / Etiology of acute bacterial meningitis in chilean children from 1989 to 1998: impact of anti H influenzae type b vaccine

Background: Acute bacterial meningitis still has a high mortality and rate of complications. Aim: To assess the impact of anti H influenzae vaccination on the epidemiology of acute bacterial meningitis in Chilean children. Material and methods: A retrospective study of hospital discharge records of patients with acute bacterial meningitis. Causative agents were studied globally, by hospital and by age group. The changes in etiology from 1989 to 1995 were also assessed. Between 1996 and 1998, only those patients with acute bacterial meningitis caused by H influenzae were recollected. Results: In the period prior to vaccination (1989-1995), 1000 cases were registered. The main causative agents were N meningitidis in 33.8 percent, H influenzas type b in 21.9 percent and S pneumoniae in 15.4 percent. The incidence of H influenzae decreased in the period from 36.4 to 9.9 percent (p<0.001) and the incidence of N meningitidis increased from 22.9 to 52.1 percent (p <0.001). The incidence of S pneumoniae did not change significantly. H influenzae predominated in children between 4 and 24 months of age and N meningitidis predominated in children over 25 months of age. In the period after the introduction of vaccination (1995-1998), there was a further decrease in the incidence of H influenzae from 10 to 2 percent (p <0.001). Until 1997, there was a considerable increase in the incidence of N meningitidis, specially in children over 25 months of age. It declined in 1998 to 38 percent. Conclusions: There was a reduction in the incidence of acute bacterial meningitis caused by H influenzae prior to the introduction of the vaccine against H influenzae type b. The decrease was more pronounced after the introduction of the vaccine