Analysis of nad2 and nad5 enables reliable identification of genotypes G6 and G7 within the species complex Echinococcus granulosus sensu lato.

The larval stages of tapeworms in the species complex Echinococcus granulosus sensu lato cause a zoonotic disease known as cystic echinococcosis (CE). Within this species complex, genotypes G6 and G7 are among the most common genotypes associated with human CE cases worldwide. However, our understanding of ecology, biology and epidemiology of G6 and G7 is still limited. An essential first step towards this goal is correct genotype identification, but distinguishing genotypes G6 and G7 has been challenging. A recent analysis based on complete mitogenome data revealed that the conventional sequencing of the cox1 (366 bp) gene fragment mistakenly classified a subset of G7 samples as G6. On the other hand, sequencing complete mitogenomes is not practical if only genotype or haplogroup identification is needed. Therefore, a simpler and less costly method is required to distinguish genotypes G6 and G7. We compared 93 complete mitogenomes of G6 and G7 from a wide geographical range and demonstrate that a combination of nad2 (714 bp) and nad5 (680 bp) gene fragments would be the best option to distinguish G6 and G7. Moreover, this method allows assignment of G7 samples into haplogroups G7a and G7b. However, due to very high genetic variability of G6 and G7, we suggest to construct a phylogenetic network based on the nad2 and nad5 sequences in order to be absolutely sure in genotype assignment. For this we provide a reference dataset of 93 concatenated nad2 and nad5 sequences (1394 bp in total) containing representatives of G6 and G7 (and haplogroups G7a and G7b), which can be used for the reconstruction of phylogenetic networks.

The benefits of analysing complete mitochondrial genomes: Deep insights into the phylogeny and population structure of Echinococcus granulosus sensu lato genotypes G6 and G7.

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the species complex Echinococcus granulosus sensu lato. Within this complex, genotypes G6 and G7 have been frequently associated with human CE worldwide. Previous studies exploring the genetic variability and phylogeography of genotypes G6 and G7 have been based on relatively short mtDNA sequences, and the resolution of these studies has often been low. Moreover, using short sequences, the distinction between G6 and G7 has in some cases remained challenging. The aim here was to sequence complete mitochondrial genomes (mitogenomes) to obtain deeper insight into the genetic diversity, phylogeny and population structure of genotypes G6 and G7. We sequenced complete mitogenomes of 94 samples collected from 15 different countries worldwide. The results demonstrated that (i) genotypes G6 and G7 can be clearly distinguished when mitogenome sequences are used; (ii) G7 is represented by two major haplogroups, G7a and G7b, the latter being specific to islands of Corsica and Sardinia; (iii) intensive animal trade, but also geographical isolation, have likely had the largest impact on shaping the genetic structure and distribution of genotypes G6 and G7. In addition, we found phylogenetically highly divergent haplotype from Mongolia (Gmon), which had a higher affinity to G6.

Heterogeneous distribution of human cystic echinococcosis after a long-term control program in Neuquén, Patagonia Argentina.

The present study is the first comprehensive analysis of human cystic echinococcosis (CE) epidemiological data carried out in the province of Neuquén, Patagonia Argentina, after 34 years of uninterrupted control program. A retrospective study of all the official records of confirmed human CE cases between 1995 and 2004 was carried out. A total of 1107 cases were reported. The overall mean annual incidence (MAI) was 24.4 per 100,000 inhabitants for the total population and 9.7/100,000 in the 0-14 year group. Distribution of cases by age and sex as well as frequency of cyst locations was analysed. Children accounted for 13.3% of total cases, indicating active transmission of the disease. Territorial distribution of cases was highly heterogeneous: MAI per 100,000 ranged from 7.9 in the Metropolitan Sanitary Area to 78.4 in the western rural areas. Higher values were recorded in small communities as Pilo Lil (800/100,000). MAI showed a significant decrease from 1995 to 1999 (43.9-18.8) but remains stable from 2000 to 2004 (15.9-15.5). These results suggest that standard control measures, despite long-term implementation, are not able to produce a sustained improvement of the epidemiological status of the disease. Further studies about local transmission cycles, definite and intermediate hosts present, Echinococcus granulosus strains or cultural behaviours in small communities are required in order to adequate the control actions in Neuquén.

Parasitosis intestinales y su relación con factores socioeconómicos y condiciones de habitat en niños de Neuquén, Patagonia, Argentina / Intestinal parasitosis in relation to socioeconomic factors and habitat conditions in children of Neuquen, Patagonia, Argentina

Se investigó la prevalencia y distribución de parásitos intestinales (PI) en niños de 2 poblaciones de diferente nivel socioeconómico del área periurbana de la ciudad de Neuquén (Sectores I y II) a fin de evaluar su relación con las condiciones de hábitat y factores socio-económicos. Se procesaron muestras seriadas de materia fecal y de escobillado anal de 126 niños entre 2 y 14 años de edad. Se registraron datos acerca de condiciones de hábitat y factores socioeconómicos mediante visitas domiciliarias y encuestas observaciones estructuradas. Se detectó presencia de PI en el 50,7 por ciento de los niños del Sector I (barrio suburbano con adecuadas condiciones sanitarias y nivel socioeconómico medio o medio-bajo) y en el 92,9 por ciento de los niños del Sector II (asentamiento marginal con deficientes condiciones sanitarias y bajo nivel socioeconómico). Se identificaron 7 especies de protozoos intestinales y 4 especies de helmintos. Blastocystis hominis fue la especie más frecuente encontrada en ambas poblaciones. No se encontraron helmintos diferentes de Enterobius vermicularis en el Sector I y la prevalencia de tales especies fue muy baja en el Sector II. Las condiciones de hábitat deficientes y los bajos parámetros socioeconómicos se relacionaron con una mayor prevalencia de PI de transmisión directa como protozoos y E. vermicularis en las poblaciones estudiadas. Sin embargo, aún en ese contexto favorable a la transmisión, las especies parasitarias que requieren estadíos intermedios de maduración en el suelo no encuentran un hábitat adecuado para su diseminación en esta región patagónica.

The prevalence and distribution of intestinal parasites (IP) were investigated in children from two populations of different socioeconomic level, located in the same area of the city of Neuquén, in order to evaluate their relationship with habitat conditions and socioeconomic factors. Serial samples of faeces and anal scraping of 126 children between 2 and 14 years from two sectors of the suburban area of Neuquen (Sector I and Sector II) were analyzed. Data concerning habitat conditions and socioeconomic parameters were obtained by home visits and an observational structured survey. Presence of IP was detected in 50.7% of children from Sector I (suburban neighborhood with adequate sanitary conditions and middle or middle low socioeconomic level) and in 92.9% from children of Sector II (marginal settlement with poor sanitary conditions and low socioeconomic status). Seven intestinal protozoan and 4 helminth species were identified. Blastocystis hominis was the most frequent species found in both populations. No helminths different from Enterobius vermicularis were found in Sector I and the prevalence of such species was very low in Sector II. Deficient habitat conditions and low socioeconomic parameters showed relation with a higher prevalence of IP of direct transmission as protozoan and E.vermicularis in the studied populations. Nevertheless, even in this context favourable to transmission, the parasitic species which require intermediate stages of development in soil, don't find an adequate habitat for dissemination in this region