Real-Time PCR in faecal samples of Triatoma infestans obtained by xenodiagnosis: proposal for an exogenous internal control

<p>Abstract</p> <p>Background</p> <p>The polymerase chain reaction (PCR) has proved to be a sensitive technique to detect <it>Trypanosoma cruzi </it>in the chronic phase of Chagas disease, which is characterized by low and fluctuating parasitemia. Another technique proposed for parasitological diagnosis in this phase of infection combines a microscopic search for motile trypomastigote forms in faecal samples (FS) obtained by xenodiagnosis (XD) with conventional PCR (XD-PCR). In this study we evaluate the use of human blood DNA as an exogenous internal control (EIC) for real time PCR (qPCR) combined with XD (XD-qPCR) using chromosome 12 (X12) detection.</p> <p>Findings</p> <p>None of the FS-XD evaluated by qPCR amplified for X12. Nevertheless, all the EIC-FS-XD mixtures amplified for X12.</p> <p>Conclusions</p> <p>We determined that X12 is useful as an EIC for XD-qPCR because we showed that the FS-XD does not contain human DNA after 30 or more days of XD incubation. This information is relevant for research on <it>T. cruzi </it>by XD-qPCR since it allows ruling out inhibition and false negative results due to DNA loss during the process of extraction and purification.</p

T. cruzi OligoC-TesT: A Simplified and Standardized Polymerase Chain Reaction Format for Diagnosis of Chagas Disease

Chagas disease (American trypanosomiasis) is caused by the protozoan parasite Trypanosoma cruzi and represents a major public health problem in Latin America. Furthermore, growing human population movements extend the disease distribution to regions outside the South American continent. Accurate diagnosis is crucial in patient care and in preventing transmission through blood transfusion, organ transplantation, or vertical transmission from mother to child. Routine diagnosis of Trypanosoma cruzi infection generally is based on detection of the host's antibodies against the parasite. However, antibody detection tests are liable to specificity problems and are of limited use in assessing treatment outcome and congenital infections. The introduction of the polymerase chain reaction (PCR) to amplify specific DNA sequences opened promising diagnostic perspectives. Despite its reported high sensitivity and specificity, broad use of the PCR technique in diagnosis of Chagas disease is hampered by its complexity and the lack of any standardization. We here present the development and evaluation of the T. cruzi OligoC-TesT, a simple and standardized dipstick format for detection of PCR amplified T. cruzi DNA. The new tool is an important step towards simplified and standardized molecular diagnosis of Chagas disease

New antiprotozoal and antiarthropod drugs Nuevos medicamentos antiprotozoarios y antiartropodos

Few developments have taken place in this area, except for the use of trimethoprim and sulfamethoxazole for isosporosis and spiramycin for cryptosporidiosis in immune suppressed patients. For parasitic arthropods, crotamiton and piretoids have been helpful in treating scabies and pediculosis, respectively

New anthelmintic drugs Nuevos medicamentos antihelmínticos.

New anti-helminthic drugs have appeared lately: benzimidazoles (mebendazole, flubendazol, and abendazole), praziquantel and ivermectin. Mebendazol and flubendazol are poorly absorbed and are effective for ascaris, oxyuriasis and trycocephalus both in adults and children. Abendazole is well absorbed and may be considered the drug of choice for ascaris and oxyuriasis at a single 400 mg dose. This drug may also be used for hydatid cyst when surgery is not possible and for cysticercosis of the nervous system. Praziquantel is useful for treatment of tenia infections and ivermectin is useful for strongyloides and trichostrongyloides. Detailed dose schedules for different parasitic diseases are given in the text

Current and developing therapeutic agents in the treatment of Chagas disease

Chagas disease must be treated in all its stages: acute, indeterminate, chronic, and initial and middle determinant chronic, due to the fact that DNA of the parasite can be demonstrated by PCR in chronic cases, where optical microscopy does not detect parasites. Nifurtimox (NF) and benznidazole (BNZ) are the drugs accepted to treat humans based upon ethical considerations and efficiency. However, both the drugs produce secondary effects in 30% of the cases, and the treatment must be given for at least 30-60 days. Other useful drugs are itraconazole and posaconazole. The latter may be the drug to treat Chagas disease in the future when all the investigations related to it are finished. At present, there is no criterion of cure for chronic cases since in the majority, the serology remains positive, although it may decrease. In acute cases, 70% cure with NF and 75% with BNZ is achieved. In congenital cases, 100% cure is obtained if the treatment is performed during the first year of life

Infecciones por parásitos más frecuentes y su manejo

Las enfermedades parasitarias constituyen un problema de salud pública por su alta frecuencia en países en vías de desarrollo y por la presencia en países desarrollados, debido a la migración de personas provenientes de países del Tercer Mundo y por su alta morbilidad. Se calcula que existen 2.800 millones de personas infectadas por geohelmintos. De acuerdo a la OMS existen 200 millones de individuos infectados con esquistosomas: 120 con filariasis linfática y 37 con oncocercosis O.volvulus (ceguera de los ríos). Un 20 a 30% de la población mundial está infectada con Toxoplasma gondii. Al año se originan entre 300 y 500 millones de nuevos casos de malaria, período en el que fallecen más de un millón de niños menores de cinco años por esta parasitosis. Hay entre 10–15 millones de individuos infectados por Trypanosoma cruzi en Latinoamérica, zoonosis que se ha extendido a Europa, Asia, Oceanía y Norteamérica, debido a la migración de personas infectadas de zonas endémicas a dichos continentes. Sólo la sarna origina más de 300 millones de personas infestadas al año. Debido a estos antecedentes creímos que sería útil revisar la epidemiología y clínica de las principales parasitosis del mundo y, a través de tablas, destacar el diagnóstico de laboratorio y la terapia tanto de las enteroparasitosis como las histo-hemoparasitosis y las originadas por artrópodos