RESUMO
The presence of malaria parasites and the serological antibody responses against whole Plasmodium falciparum and the Pf155 antigen were studied in the population of a small rural locality in Haiti in December 1985. Only 7 (1.5%) of the individuals were found to be infected with P. falciparum, the only species observed. Antibodies to P. falciparum were detected in an ELISA in 38.2% of the sera, the positivity rates being age-related. Anti-Pf155 antibodies were detected in 12.5% and 13.6% of individuals by two different techniques used. The anti-Pf155 positivity rates increased only after 25 years of age. No trends were detected for a clear-cut protective value of Pf155 antibodies against clinical malaria and further longitudinally conducted field surveys are needed to satisfactorily assess the potential protective effect of Pf155 antibodies.
Assuntos
Anticorpos Antiprotozoários/análise , Antígenos de Protozoários/imunologia , Malária/imunologia , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Feminino , Haiti , Humanos , Lactente , Malária/epidemiologia , Masculino , Plasmodium falciparumRESUMO
Between 1981 and 1983, in vivo and in vitro studies were conducted in Haiti to assess the responsiveness of Plasmodium falciparum to chloroquine. The standard tests successfully performed included 92 WHO standardized in vivo field tests and 160 in vitro tests (64 macrotests, 33 microtests, and 63 48-hr tests). No clearcut evidence of chloroquine resistance was detected. In 3 in vivo and 5 in vitro tests, a decreased susceptibility to the drug was suggested, but these isolated findings failed to be corroborated by parallel alternate tests. In addition, during the initial trial of an alternate monitoring system, 339 simplified 7-day in vivo tests were successfully performed, with no suggestion of resistance detected. This simplified 7-day in vivo test potentially represents an efficient low cost method for monitoring drug resistance in many developing countries.
Assuntos
Cloroquina/farmacologia , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Animais , Cloroquina/uso terapêutico , Resistência a Medicamentos , Haiti , Humanos , Malária/parasitologia , Plasmodium falciparum/crescimento & desenvolvimentoRESUMO
An in vitro microtest for assessing the susceptibility of Plasmodium falciparum to sulfadoxine-pyrimethamine (S-P) was developed following WHO guidelines. Paraaminobenzoic acid and folic acid were depleted in the culture medium used, the test wells were predosed with sulfadoxine and pyrimethamine at a constant ratio of 80:1, and the parasites were incubated for 48 hours. Optimum parasite multiplication was obtained with a 2% erythrocyte suspension in medium supplemented with 12% serum. During in vitro studies with laboratory-adapted isolates, response patterns were obtained which distinguished 3 isolates with documented in vivo sensitivity to S-P from 2 isolates with documented in vivo resistance to S-P. In addition, among the three S-P-sensitive isolates, one isolate that was pyrimethamine-resistant in vitro had a higher S-P inhibitory endpoint than 2 isolates that were pyrimethamine-sensitive in vitro. The S-P microtest was further evaluated in combined in vivo and in vitro studies in Port-au-Prince, Haiti. Twenty-six patients infected with P. falciparum were treated with standard doses of S-P, resulting in prompt clearance of parasitaemia, with no recurrence in the 24 patients who completed a 28-day follow-up period. Parallel in vitro tests with pyrimethamine alone showed 3 pyrimethamine-resistant isolates out of 22 successful tests on the patients' blood samples. In 23 successful S-P tests, the known in vivo S-P-sensitive parasites were inhibited at S-P concentrations that were generally lower for in vitro pyrimethamine-sensitive isolates than for in vitro pyrimethamine-resistant ones.
Assuntos
Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Sulfanilamidas/farmacologia , Animais , Combinação de Medicamentos , Haiti , Humanos , Testes de Sensibilidade Microbiana , Pirimetamina/administração & dosagem , Pirimetamina/uso terapêutico , Sulfadoxina/administração & dosagem , Sulfadoxina/uso terapêuticoRESUMO
Eighteen patients with Plasmodium falciparum infection were studied in Port-au-Prince, Haiti, to monitor the response of the malaria parasite to sulfadoxine-pyrimethamine. In all infections the parasitaemia was cleared rapidly following treatment with standard dose of the drug combination; no recrudescence was observed during follow-up periods of 1 week (4 patients) and 4 weeks (14 patients). Parallel in vitro tests indicated that 5 of the 16 isolates successfully tested were resistant to pyrimethamine alone.