Brote de fiebre amarilla selvatica en el departamento de Santa Cruz-Bolivia, año 1999 / Bud of wild Yellow Fever in departament of Santa Cruz - Bolivia, year 1999

Entre el mes de enero y abril de 1999 se presento un brote de fiebre amarilla selvatica en el departamento de Santa Cruz. CENETROP apoyo a la dirección departamental de salud procesando las muestras de suero recolectadas por el personal de epidemiologia. Se recibieron un total de 175 muestras para ser analizadas en el laboratorio de arbovirosis de CENETROP. De las 175 muestras 51 (29.1 por ciento) fueron positivas para fiebre amarilla. El material enviado a CENETROP principalmente por la Unidad Departamental de Epidemiologia y centros medicos asistenciales, consistio en muestras de suero de pacientes con manifestaciones clinicas compatibles con fiebre amarilla o necropsias de higado de los pacientes fallecidos con manifestaciones clinicas similares. En total se han confirmados por laboratorio 51 casos con 21 (41.2 x ciento) fallecidos. Se indica la regularidad temporal y geografica de los brotes, que deberia inducir actividades de control de programadas. Se destaca la observacion del 20 x ciento de los casos en niños entre 5 a 10 años de edad. Del total de casos el 33 x ciento fueron mujeres. Finalmente, se llama la atencion sobre el peligro de la ocurrencia de casos urbanos de fiebre amarilla, por la presencia de casos selvaticos que son trasladados a la ciudad en fase viremica y la alta infestacion domiciliaria por Aedes aegypti en la ciudad de Santa Cruz

Mutations in Plasmodium falciparum dihydrofolate reductase and dihydropteroate synthase and epidemiologic patterns of pyrimethamine-sulfadoxine use and resistance.

To assess the relationship between mutations in Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) and clinical pyrimethamine-sulfadoxine resistance, polymerase chain reaction surveys and analyses for new mutations were conducted in four countries with increasing levels of pyrimethamine-sulfadoxine resistance: Mali, Kenya, Malawi, and Bolivia. Prevalence of mutations at DHFR codon 108 and a new mutation at DHPS 540 correlated with increased pyrimethamine-sulfadoxine resistance (P < .05). Mutations at DHFR 51, DHFR 59, and DHPS 437 correlated with resistance without achieving statistical significance. Mutations at DHFR 164 and DHPS 581 were common in Bolivia, where pyrimethamine-sulfadoxine resistance is widespread, but absent in African sites. Two new DHFR mutations, a point mutation at codon 50 and an insert at codon 30, were found only in Bolivia. DHFR and DHPS mutations occur in a progressive, stepwise fashion. Identification of specific sets of mutations causing in vivo drug failure may lead to the development of molecular surveillance methods for pyrimethamine-sulfadoxine resistance.

Deteccion de casos autoctonos de malaria urbana por P. vivax en Barrios el Plan 3000, Santa Cruz-Bolivia / Detection of autocthonous cases of urban malaria by P. vivax in districts of the Plan 3000, Santa Cruz-Bolivia

Por medio de una encuesta epidemiologica realizada a 61 pacientes con diagnostico confirmado de infeccion por P.vivax en el "Plan 3000", una zona peri-urbana de la ciudad de Santa Cruz, se observo que 9 (15 por ciento) de los casos se presentaron en niños menores de 5 años y que 44 (72 por ciento) reportaron no haber tenido antecedente paludico, no haber vivido en los ultimos 5 años en zonas endemicas, ni haber visitado estas hasta 30 dias antes de la aparicion del cuadro febril lo que hace improbable una recaida por hipnozoito o malaria importada. Ademas, el numero de casos de malaria se concentro en los barrios donde las condiciones ecologicas para la reproduccion del vector son mas favorables tal como fue verificado con capturas larvarias del vector anofeles pseudopunctipennis. todas estas observaciones nos permiten indicar que efectivamente existe transmision local de P.vivax en la ciudad de Santa Cruz y que son necesarios estudios posteriores para cuantificar la magnitud del problema y caracterizarlo con vista de tomar eficientes medidas de control

Evidence through crossmating experiments of a species complex in Anopheles pseudopunctipennis sensu lato: a primary malaria vector of the American continent.

Crossmating experiments were conducted to determine if postmating reproductive barriers are involved in the maintenance of genetic divergence among populations of Anopheles pseudopunctipennis sensu lato, a primary malaria vector of the American continent. Reciprocal crosses were conducted between colony and wild strains from Mexico, Bolivia, and Peru. Hybridization experiments revealed unidirectional male/female hybrid sterility in crosses between Mexican females and South American males. The data presented provide the first evidence that genetic differences exist among geographic strains of An. pseudopunctipennis in neotropical America. There is a consistent pattern suggesting the presence of at least two allopatric sibling species. One species occurs in central Mexico, the other in the South American Andean Cordillera.

Characterization of Anopheles pseudopunctipennis sensu lato from three countries of neotropical America from variation in allozymes and ribosomal DNA.

Enzyme electrophoresis and restriction fragment length polymorphism (RFLP) analysis of Anopheles pseudopunctipennis sensu lato from nine isolated populations in neotropical America confirmed previous observations that it constitutes a species complex. Electrophoretic studies showed fixed differences at two enzyme loci, glycerol dehydrogenase (Gcd) and phosphoglucomutase (Pgm), suggesting limited or no gene flow between populations from Mexico and South America. In addition, analysis of genetic distance showed two distinctive clusters, one from Mexico and the other from South America, separated at a Nei's distance level of 0.13, a value consistent in magnitude with that of other anopheline sibling species. The RFLP analysis revealed the presence of a ribosomal DNA fragment in Mexican strains that was absent in strains from South America. Two species have been identified through these studies, one provisionally named An. pseudopunctipennis A, a species from central Mexico, and the other An. pseudopunctipennis B, for the species found in the interAndean valleys and Andean slopes in regions of Peru and Bolivia. This research provides information required to elucidate the status of the different species of the An. pseudopunctipennis complex as vectors of malaria in the Americas.

Genetic evidence of a species complex in Anopheles pseudopunctipennis sensu lato.

This preliminary report provides information concerning genetic variation in the vector mosquito Anopheles pseudopunctipennis sensu lato that could have malaria control implications. Because of inconsistencies in malaria transmission patterns within geographic zones inhabited by this vector, the possibility that it represents a species complex was investigated. Hybrid crossing studies, electrophoretic analysis of enzyme variation, and DNA restriction studies were carried out in mosquitoes captured in nine areas of Mexico, Bolivia, and Peru. The findings demonstrated the existence of a species complex believed to have resulted from allopatric speciation. This research points to a need for establishing the geographic distribution of the newly recognized species because of their potential influence on malaria control.

[Genetic evidence of a species complex in Anopheles pseudopunctipennis pseudopunctipennis]. / Evidencia genética de un complejo de especie en Anopheles pseudopunctipennis pseudopunctipennis.

In light of inconsistencies in the pattern of malaria transmission within geographical areas inhabited by Anopheles pseudopunctipennis pseudopunctipennis, a study was carried out to investigate the possibility that this vector constitutes a species complex. Hybrid crossing studies, electrophoretic analysis of enzyme loci, and DNA restriction analysis were conducted on mosquitoes captured at nine sites in Mexico, Bolivia, and Peru. The sterility of generations resulting from cross-mating of Mexican female mosquitoes and South American male mosquitoes; the results of electrophoretic analysis, which showed differences at two loci; and a genetic distance value of 0.13 confirmed the existence of a species complex, probably produced by allopatric speciation. It is concluded that the geographic distribution of this newly discovered species complex should be defined, in view of its potential effect on malaria control.