Pyrimethamine-sulfadoxine treatment of uncomplicated Plasmodium falciparum malaria in Lao PDR.

A 28-day in vivo treatment trial to evaluate the efficacy of pyrimethamine/sulfadoxine (Fansidar, PS) was conducted in 21 Lao patients with uncomplicated Plasmodium falciparum malaria. Sixteen patients (76%) were completely cured with PS without any reappearance of asexual stage parasitemia during the follow-up examination. On the other hand, 5 patients (24%) failed to respond to this trial medication, resulting in recrudescence of asexual stage P. falciparum malaria. PS resistance resulted in higher prevalence of post-treatment gametocytemia, 25% gametocyte carriers among PS sensitive cases versus 75% of the resistant cases. These findings suggest that although the level of PS resistance is still valid for treatment of malaria in the study area of Lao PDR, post-treatment induction of gametocytemia among resistant cases may result an increase in transmission rate of PS resistant falciparum malaria.

A molecular epidemiologic study of point mutations for pyrimethamine-sulfadoxine resistance of Plasmodium falciparum isolates from Lao PDR.

To understand the current condition of pyrimethamine-sulfadoxine (PS) resistant falciparum malaria in Lao PDR, the frequency of point mutations in dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) genes of Plasmodium falciparum were examined in 50 blood samples collected from the patients with P. falciparum infection in Southern Lao PDR. Point mutations in 5 codons of the DHFR gene, which is known to be related to pyrimethamine resistance, were detected in 15 out of the 50 samples (30%). Among the 15 samples, 10 samples showed a double mutation of codons 59 and 108 (Cys59Arg with Ser108Asn). In the remaining 5 samples, an additional mutation was observed in codon 51 (Asn51 lle), providing a triple mutation of codons 51, 59 and 108. On the other hand, point mutations in the 4 codons of DHPS gene related to sulfadoxine resistance were observed only in 2 samples (4.0%), namely in codon 437 (Ala437Gly). Only one sample showed mutations in both DHFR and DHPS genes. From the results, it should be considered that the frequency of PS resistant malaria is still low in Lao PDR. Continuous monitoring for the PS resistant malaria, however, is necessary because of the increasing use of PS in this country.

Malaria parasite developmental analyses by the nested polymerase chain reaction method: an implication for the evaluation of mosquito infection rates in epidemiological studies.

A malaria mosquito vector, Anopheles saperoi, and a non-vector, Aedes albopictus, were allowed to feed on mice infected with murine malaria, Plasmodium yoelii nigeriensis, and were subsequently monitored for the development of parasites by the nested polymerase chain reaction (PCR) method, using Plasmodium genus-specific primer pairs. The mosquitos were divided into two parts, head/thorax and abdomen, for DNA analyses. The parasite DNA and murine DNA for each mosquito were examined in parallel. In both groups of mosquitos, murine DNA was detected up to 4 days post-blood meal in both the head/thorax and abdomen. After 4 days, the murine DNA fell below detectable limits. Murine DNA and parasite DNA remained undigested for the first 4 days post-blood meal. Parasite DNA was detected in the abdomen of 25% (3/12) of Ae. albopictus on day five and 10% (1/10) on day six, after murine DNA had fallen below detectable limits. Parasite DNA was not detected in the head/thorax of Ae. albopictus on those days or afterwards in either the head/thorax or abdomen, demonstrating that the parasite detected on days 5 and 6 in the abdomen degenerated and did not develop into mature oocysts or sporozoites. In the vector An. saperoi, parasite DNA was detected continuously in the head/thorax and abdomen for many days after the murine DNA had fallen below detectable limits. The detection rate of parasite DNA in the head/thorax of An. saperoi increased gradually from day 8 post blood meal until it reached a maximum level of 71.4% (15/21 12 days post-infection. Parasite DNA in abdomen reached its maximum level of 81% (17/21) 10 days post-blood meal. The implications of these results for the design and interpretation of epidemiological surveys is discussed.

Intranasal sensitization with Blomia Tropicalis antigens induces allergic responses in mice characterized by elevated antigen-specific and non-specific serum ige and peripheral blood eosinophil counts

Para avaliar a capacidade alergizante do antígeno da Blomia tropicalis (Bt) a produção de IgE específica e não específica a antígeno Bt foi monitorada em camundongos BALB/c após exposição ao antígeno por via nasal. Foi evidenciado que Bt contem um alérgeno funcional em seus componentes. Os componentes alergênicos entretanto, quando administrados por via intra-nasal, sem qualquer adjuvante, não induzem resposta IgE durante um pequeno período. Por outro lado, a inoculação intra-nasal de antígenos Bt aumentou a resposta sérica de IgE em camundongos pré-tratados por uma injeção inicial sensibilizante sub-cutânea aos mesmos antígenos. A inoculação do antígeno Bt sem as injeções sensibilizantes iniciais induziu a produção de anticorpos IgE somente quando o antígeno foi administrado de maneira contínua, por um período longo de mais de 24 semanas. Mesmo quando as injeções sensibilizantes iniciais foram ausentes, o antígeno Bt inoculado com a toxina de cólera (CT) como adjuvante mucoso também aumentou de maneira significante a resposta IgE antígeno específica do Bt dependendo da dose de CT administrada conjuntamente. O presente estudo também demonstrou que camundongos inoculados com antígeno Bt/CT mostram aumento do nível IgE não específico no soro e médias de eosinófilos no sangue periférico sem qualquer elevação da contagem total de leucócitos. A análise por Immunoblot demonstrou cinco principais componentes antigênicos reativos aos anticorpos IgE induzidos. Estes componentes na posição 44-64 kilodaltons foram considerados importantes antígenos-candidatos para o diagnóstico da alergia relacionada ao ácaro.

Field application and evaluation of a rapid immunochromatographic test for detection of Plasmodium falciparum infection among the inhabitants of Lao PDR.

Field application and evaluation of a rapid immunochromatographic test (ICT) for detection of Plasmodium falciparum infection were performed in 13 villages in a southern province of Lao PDR in 1999. More than 2,000 inhabitants, accounting for 61.8% of the total estimated population, were examined. Malaria infection was confirmed in all villages surveyed by ICT and microscopic diagnosis. The positive rates of P. falciparum malaria by microscopy ranged from 9.7% to 59.2% (mean 27.2%), whereas by ICT they were from 11.6% to 64.5% (mean 29.8%). The positive rates by ICT were generally higher in 8 out of 13 villages. However, a significant difference between the positive rates by microscopy and ICT was not observed in all villages. Plasmodium falciparum infection was actually confirmed by microscopy in 84.1% of specimens that tested positive by ICT. The results by ICT were consistent with those of the microscopic diagnosis, the discrepancy of the results was less than 10% (141/2,066). The ICT was falsely-positive in 4.7% and falsely-negative in 2.1% of the test cases. These results showed the efficacy of ICT not only in the diagnosis of the respective cases, but also in the mass-examination in the field.

Prevalence of intestinal parasitic infection in five farms in Holambra, Sao Paulo, Brazil

Uma pesquisa coproparasitologica foi realizada em 222 habitantes de cinco fazendas de Holambra, localizada a 30 Km ao norte de Campinas, SP, Brasil, em outubro de 1992. Aproximadamente 70 por cento dos habitantes apresentaram pelo menos um tipo de parasitose intestinal. O indice de positividade das 6 especies de helmintos e de 7 protozoarios na populacao foi o seguinte: Ascaris lumbricoides (5,4 por cento ); Trichuris trichiura (8,6 por cento ); Necator americanus (19,8 por cento ); Strongyloides stercoralis (10,4 por cento ); Enterobius vermiculares (1,4 por cento ); Hymenolepis nana (0,9 por cento ); Entamoeba histolytica (3,2 por cento ); E. hartmanni (2,7 por cento); E. coli (9,9 por cento ); Endolimax nana (14,0 por cento ); Iodamoeba butschlii (2,3 por cento ); Giardia lamblia (10,4 por cento ); Blastocytis hominis (37,4 por cento ). O indice de positividade para infeccao por helmintos foi aparentemente maior na populacao mais jovem (menores de 16 anos) do que no grupo de populacao com idades acima de 16 anos, ao contrario do indice de infeccao pelos protozoarios que foi mais elevado na populacao adulta. Utilizando um novo e sensivel metodo atraves de cultura em agar, encontrou-se um indice de infeccao de 10,4 por cento para strongyloides sp.

Serodiagnosis of strongyloidiasis: the application and significance

O diagnostico parasitologico baseado no exame de fezes e muitas vezes dificil, principalmente nos casos de infeccoes cronicas ou leves pelo S. stercoralis. Mesmo utilizando o mais novo e sensivel metodo (cultura em placas de agar) e essencial examinar repetidamente as amostras fecais, para um diagnostico correto. E importante ressaltar tambem que o resultado negativo nao indica de modo inequivoco a ausencia da infeccao. Por outro lado, varios sorologicos recentementes desenvolvidos para estrongiloidiase tem provado a sua eficacia quando usados para complementar exames parasitologicos. Para demonstrar infeccao por Strongyloides desenvolvemos dois tipos de testes sorologicos - ELISA e GPAT - e, com base em nossos recentes estudos, apresentamos uma opiniao sobre sua possivel aplicacao para screening em massa, estudos epidemiologicos e avaliacao pos-tratamento de estrongiloidiases.

Gelatin particle indirect agglutination test for serodiagnosis of schistosomiasis: comparative study with enzyme-linked immunosorbent assay

Um novo teste sorologico, o teste de aglutinacao com particulas de gelatina (TAPG), foi utilizado para o diagnostico sorologico de esquistossomose mansonica. Esta tecnica mostra que a sensibilidade (90,6 por cento) e especificidade (97,8 por cento) chegam proximas do teste de enzima imunoensaio. O TAPG pode ser facil e rapidamente realizado sem equipamentos especializados usando particulas liofilizadas sensibilizadas com o antigeno. O teste mostrou ser tambem util em condicoes de campo para triagem em massa da infeccao pelo Schistosoma mansoni.

Pruba de anglutinación indirecta de partículas de gelatina, un medio simple y sensible para el serodiagnóstico de la de la enfermedad de Chagas / Annual Reports 1992 / The gelatine praticle indirect agglutination test, a means of simple and sensitive serodiagnósis of Chagas' disease

An indirect agglutination test using Trypanosoma cruzi antigen-coated gelatin particles was employed to Trypanosomiasis in Paraguay. Results with this test were quite comparable to those obtained with enzyme-linked immusorbent assay (Elisa). Furthermore, nonspecific reaction to the gelatin particles alone was not found in either acute or chronic infection. This method is more convenient than the ELISA, since the antigen-conjugate particles are stable for at least 1 year at 47 ºC and the test itself is short and simple to perform and does not require specialized equipment