Tracking of Nascent Matrix Deposition during Muscle Stem Cell Activation across Lifespan Using Engineered Hydrogels.

Adult stem cells occupy a niche that contributes to their function, but how stem cells rebuild their microenvironment after injury remains an open-ended question. Herein, biomaterial-based systems and metabolic labeling are utilized to evaluate how skeletal muscle stem cells deposit extracellular matrix. Muscle stem cells and committed myoblasts are observed to generate less nascent matrix than muscle resident fibro-adipogenic progenitors. When cultured on substrates that matched the stiffness of physiological uninjured and injured muscles, muscle stem cells increased nascent matrix deposition with activation kinetics. Reducing the ability to deposit nascent matrix by an inhibitor of vesicle trafficking (Exo-1) attenuated muscle stem cell function and mimicked impairments observed from muscle stem cells isolated from old muscles. Old muscle stem cells are observed to deposit less nascent matrix than young muscle stem cells, which is rescued with therapeutic supplementation of insulin-like growth factors. These results highlight the role of nascent matrix production with muscle stem cell activation.

Cellular mechanotransduction of human osteoblasts in microgravity.

Astronauts experience significant and rapid bone loss as a result of an extended stay in space, making the International Space Station (ISS) the perfect laboratory for studying osteoporosis due to the accelerated nature of bone loss on the ISS. This prompts the question, how does the lack of load due to zero-gravity propagate to bone-forming cells, human fetal osteoblasts (hFOBs), altering their maturation to mineralization? Here, we aim to study the mechanotransduction mechanisms by which bone loss occurs in microgravity. Two automated experiments, 4 microfluidic chips capable of measuring single-cell mechanics of hFOBs via aspiration and cell spheroids incubated in pressure-controlled chambers, were each integrated into a CubeLab deployed to the ISS National Laboratory. For the first experiment, we report protrusion measurements of aspirated cells after exposure to microgravity at the ISS and compare these results to ground control conducted inside the CubeLab. Our analysis revealed slightly elongated protrusions for space samples compared to ground samples indicating softening of hFOB cells in microgravity. In the second experiment, we encapsulated osteoblast spheroids in collagen gel and incubated the samples in pressure-controlled chambers. We found that microgravity significantly reduced filamentous actin levels in the hFOB spheroids. When subjected to pressure, the spheroids exhibited increased pSMAD1/5/9 expression, regardless of the microgravity condition. Moreover, microgravity reduced YAP expression, while pressure increased YAP levels, thus restoring YAP expression for spheroids in microgravity. Our study provides insights into the influence of microgravity on the mechanical properties of bone cells and the impact of compressive pressure on cell behavior and signaling in space.

Cellular mechanotransduction of human osteoblasts in microgravity.

Astronauts experience significant and rapid bone loss as a result of an extended stay in space, making the International Space Station (ISS) the perfect laboratory for studying osteoporosis due to the accelerated nature of bone loss on the ISS. This prompts the question, how does the lack of load due to zero-gravity propagate to bone-forming cells, human fetal osteoblasts (hFOBs), altering their maturation to mineralization? Here, we aim to study the mechanotransduction mechanisms by which bone loss occurs in microgravity. Two automated experiments, microfluidic chips capable of measuring single-cell mechanics via aspiration and cell spheroids incubated in pressure-controlled chambers, were each integrated into a CubeLab deployed to the ISS National Laboratory. For the first experiment, we report protrusion measurements of aspirated cells after exposure to microgravity at the ISS and compare these results to ground control conducted inside the CubeLab. We found slightly elongated protrusions for space samples compared to ground samples indicating softening of hFOB cells in microgravity. In the second experiment, we encapsulated osteoblast spheroids in collagen gel and incubated the samples in pressure-controlled chambers. We found that microgravity significantly reduced filamentous actin levels in the hFOB spheroids. When subjected to pressure, the spheroids exhibited increased pSMAD1/5/9 expression, regardless of the microgravity condition. Moreover, microgravity reduced YAP expression, while pressure increased YAP levels, thus restoring YAP expression for spheroids in microgravity. Our study provides insights into the influence of microgravity on the mechanical properties of bone cells and the impact of compressive pressure on cell signaling in space.

Quantification of local matrix deposition during muscle stem cell activation using engineered hydrogels.

Adult stem cells occupy a niche that contributes to their function, but how stem cells remodel their microenvironment remains an open-ended question. Herein, biomaterials-based systems and metabolic labeling were utilized to evaluate how skeletal muscle stem cells deposit extracellular matrix. Muscle stem cells and committed myoblasts were observed to generate less nascent matrix than muscle resident fibro-adipogenic progenitors. When cultured on substrates that matched the stiffness of physiological uninjured and injured muscles, the increased nascent matrix deposition was associated with stem cell activation. Reducing the ability to deposit nascent matrix in muscle stem cells attenuated function and mimicked impairments observed from muscle stem cells isolated from old aged muscles, which could be rescued with therapeutic supplementation of insulin-like growth factors. These results highlight how nascent matrix production is critical for maintaining healthy stem cell function.

Maresin 1 repletion improves muscle regeneration after volumetric muscle loss.

The acute traumatic or surgical loss of skeletal muscle, known as volumetric muscle loss (VML), is a devastating type of injury that results in exacerbated and persistent inflammation followed by fibrosis. The mechanisms that mediate the magnitude and duration of the inflammatory response and ensuing fibrosis after VML remain understudied, and as such, the development of regenerative therapies has been limited. To address this need, we profiled how lipid mediators, which are potent regulators of the immune response after injury, varied with VML injuries that heal or result in fibrosis. We observed that non-healing VML injuries displayed increased pro-inflammatory eicosanoids and a lack of pro-resolving lipid mediators. Treatment of VML with a pro-resolving lipid mediator synthesized from docosahexaenoic acid, called Maresin 1, ameliorated fibrosis through reduction of neutrophils and macrophages and enhanced recovery of muscle strength. These results expand our knowledge of the dysregulated immune response that develops after VML and identify a novel immuno-regenerative therapeutic modality in Maresin 1.

Proregenerative extracellular matrix hydrogel mitigates pathological alterations of pelvic skeletal muscles after birth injury.

Pelvic floor disorders, including pelvic organ prolapse and urinary and fecal incontinence, affect millions of women globally and represent a major public health concern. Pelvic floor muscle (PFM) dysfunction has been identified as one of the leading risk factors for the development of these morbid conditions. Childbirth, specifically vaginal delivery, has been recognized as the most important potentially modifiable risk factor for PFM injury; however, the precise mechanisms of PFM dysfunction after parturition remain elusive. In this study, we demonstrated that PFMs exhibit atrophy and fibrosis in parous women with symptomatic pelvic organ prolapse. These pathological alterations were recapitulated in a preclinical rat model of simulated birth injury (SBI). The transcriptional signature of PFMs after injury demonstrated an impairment in muscle anabolism, persistent expression of genes that promote extracellular matrix (ECM) deposition, and a sustained inflammatory response. We also evaluated the administration of acellular injectable skeletal muscle ECM hydrogel for the prevention of these pathological alterations. Treatment of PFMs with the ECM hydrogel either at the time of birth injury or 4 weeks after injury mitigated PFM atrophy and fibrosis. By evaluating gene expression, we demonstrated that these changes are mainly driven by the hydrogel-induced enhancement of endogenous myogenesis, ECM remodeling, and modulation of the immune response. This work furthers our understanding of PFM birth injury and demonstrates proof of concept for future investigations of proregenerative biomaterial approaches for the treatment of injured pelvic soft tissues.

Muscle stem cells and fibro-adipogenic progenitors in female pelvic floor muscle regeneration following birth injury.

Pelvic floor muscle (PFM) injury during childbirth is a key risk factor for pelvic floor disorders that affect millions of women worldwide. Muscle stem cells (MuSCs), supported by the fibro-adipogenic progenitors (FAPs) and immune cells, are indispensable for the regeneration of injured appendicular skeletal muscles. However, almost nothing is known about their role in PFM regeneration following birth injury. To elucidate the role of MuSCs, FAPs, and immune infiltrate in this context, we used radiation to perturb cell function and followed PFM recovery in a validated simulated birth injury (SBI) rat model. Non-irradiated and irradiated rats were euthanized at 3,7,10, and 28 days post-SBI (dpi). Twenty-eight dpi, PFM fiber cross-sectional area (CSA) was significantly lower and the extracellular space occupied by immune infiltrate was larger in irradiated relative to nonirradiated injured animals. Following SBI in non-irradiated animals, MuSCs and FAPs expanded significantly at 7 and 3 dpi, respectively; this expansion did not occur in irradiated animals at the same time points. At 7 and 10 dpi, we observed persistent immune response in PFMs subjected to irradiation compared to non-irradiated injured PFMs. CSA of newly regenerated fibers was also significantly smaller following SBI in irradiated compared to non-irradiated injured PFMs. Our results demonstrate that the loss of function and decreased expansion of MuSCs and FAPs after birth injury lead to impaired PFM recovery. These findings form the basis for further studies focused on the identification of novel therapeutic targets to counteract postpartum PFM dysfunction and the associated pelvic floor disorders.

Past and present of cystic echinococcosis in Bolivia.

Viable eggs of the canine intestinal tapeworm Echinococcus granulosus sensu lato (s.l.) infect various intermediate hosts causing cystic echinococcosis (CE). Furthermore, CE represents a serious zoonosis causing a significant global burden of disease. CE is highly endemic in South America, including Argentina, Brazil, Chile, Uruguay, and Peru. For Bolivia, no official data concerning the incidence in humans or the number of livestock and dogs infected are available. However, it is well known that CE occurs in Bolivia. We aim here to fill the gap in the current knowledge of the epidemiological situation of CE in Bolivia, providing a historical overview of documents published within the country, which have never been comprehensively reviewed. The very first documentation of E. granulosus infection in animals dates in 1910, while the first human case was reported in 1913. In total, 876 human CE cases have been reported in the scientific literature, with an apparent increase since the 1970s. In the absence of other epidemiological studies, the highest prevalence in human comes from Tupiza, Potosí Department, where 4.1% (51/1,268) of the population showed signs of CE at mass ultrasound screening in 2011. In the same report, 24% of dog faecal samples were positive for coproantigens of E. granulosus s.l. in ELISA. The highest prevalence in intermediate hosts reported at abattoir reached 37.5% in cattle from Potosí, followed by 26.9% in llamas from Oruro, 2.4% in pigs and 1.4% in sheep from La Paz. Finally, Echinococcus granulosus sensu stricto (s.s.), Echinococcus ortleppi (G5), and Echinococcus intermedius (G7) have been identified in Bolivia. Data reviewed here confirm that E. granulosus s.l. is circulating in Bolivia and that a proper prospective nationwide epidemiological study of CE is urgently needed to define transmission patterns as a basis for the planning and implementation of future control measurements.

Quantifying the Effects of Aging on Morphological and Cellular Properties of Human Female Pelvic Floor Muscles.

Age-related pelvic floor muscle (PFM) dysfunction is a critical defect in the progression to pelvic floor disorders (PFDs). Despite dramatic prevalence of PFDs in older women, the underlying pathophysiology of age-related PFM dysfunction remains poorly understood. Using cadaveric specimens, we quantified aging effects on functionally relevant PFM properties and compared PFMs with the appendicular muscles from the same donors. PFMs, obturator internus, and vastus lateralis were procured from younger (N = 4) and older (N = 11) donors with known obstetrical and medical history. Our findings demonstrate that PFMs undergo degenerative, rather than atrophic, alterations. Importantly, age-related fibrotic degeneration disproportionally impacts PFMs compared to the appendicular muscles. We identified intramuscular lipid accumulation as another contributing factor to the pathological alterations of PFMs with aging. We observed a fourfold decrease in muscle stem cell (MuSC) pool of aged relative to younger PFMs, but the MuSC pool of appendicular muscles from the same older donors was only twofold lower than in younger group, although these differences were not statistically significant. Age-related degeneration appears to disproportionally impact PFMs relative to the appendicular muscles from the same donors. Knowledge of tissue- and cell-level changes in aged PFMs is essential to promote our understanding of the mechanisms governing PFM dysfunction in older women.

First report in pre-Columbian mummies from Bolivia of Enterobius vermicularis infection and capillariid eggs: A contribution to Paleoparasitology studies.

OBJECTIVE: This study was designed to search for ancient parasites in abdominal content and coprolites from Bolivian mummies. MATERIALS: Twelve mummified individuals from the Andean highlands, housed at the National Museum of Archaeology (MUNARQ) in La Paz, Bolivia. METHODS: Microscopic analysis of rehydrated samples (coprolites and abdominal content), following Lutz's spontaneous sedimentation technique. RESULTS: Eggs of Enterobius vermicularis were identified in coprolites from one mummy, and capillariid eggs in the organic abdominal content from another individual. CONCLUSIONS: This is the first evidence of ancient intestinal parasites in Bolivian mummies. SIGNIFICANCE: This pioneering study focused on the search of ancient intestinal parasites in human remains of the Bolivian Andes and contributes to greater knowledge of paleoparasitology in South America. LIMITATIONS: All mummies in the MUNARQ belonged to the Andean Bolivian highlands (post-Tiwanaku era or Late Intermediate Period), although the exact provenance of the material and the associated contexts are not well recorded. SUGGESTIONS FOR FURTHER RESEARCH: Considering the great number of well-known archaeological sites and other unexplored sites in Bolivia, in addition to large collections in museums, further paleopathological and paleoparasitological molecular studies in mummies and skeletons are called for.

Genetic uniformity, geographical spread and anthropogenic habitat modifications of lymnaeid vectors found in a One Health initiative in the highest human fascioliasis hyperendemic of the Bolivian Altiplano.

BACKGROUND: Fascioliasis is a snail-borne zoonotic trematodiasis emerging due to climate changes, anthropogenic environment modifications, and livestock movements. Many areas where Fasciola hepatica is endemic in humans have been described in Latin America altitude areas. Highest prevalences and intensities were reported from four provinces of the northern Bolivian Altiplano, where preventive chemotherapy is ongoing. New strategies are now incorporated to decrease infection/re-infection risk, assessment of human infection sources to enable efficient prevention measures, and additionally a One Health initiative in a selected zone. Subsequent extension of these pilot interventions to the remaining Altiplano is key. METHODS: To verify reproducibility throughout, 133 specimens from 25 lymnaeid populations representative of the whole Altiplano, and 11 used for population dynamics studies, were analyzed by rDNA ITS2 and ITS1 and mtDNA cox1 and 16S sequencing to assess their classification, variability and geographical spread. RESULTS: Lymnaeid populations proved to belong to a monomorphic group, Galba truncatula. Only a single cox1 mutation was found in a local population. Two cox1 haplotypes were new. Comparisons of transmission foci data from the 1990's with those of 2018 demonstrated an endemic area expansion. Altitudinal, northward and southward expansions suggest movements of livestock transporting G. truncatula snails, with increasing temperatures transforming previously unsuitable habitats into suitable transmission areas. Transmission foci appear to be stable when compared to past field observations, except for those modified by human activities, including construction of new roads or control measures undertaken in relation to fascioliasis. CONCLUSIONS: For a One Health initiative, the control of only one Fasciola species and snail vector species simplifies efforts because of the lower transmission complexity. Vector monomorphism suggests uniformity of vector population responses after control measure implementation. Hyperendemic area outer boundary instability suggests a climate change impact. All populations outside previously known boundaries were close to villages, human dwellings and/or schools, and should therefore be considered during disease control planning. The remarkable southward expansion implies that a fifth province, Aroma, should now be included within preventive chemotherapy programmes. This study highlights the need for lymnaeid molecular identification, transmission foci stability monitoring, and potential vector spread assessment.

Mechanical impact of parturition-related strains on rat pelvic striated sphincters.

AIMS: To define the operational resting sarcomere length (Ls ) of the female rat external urethral sphincter (EUS) and external anal sphincter (EAS) and to determine the mechanism of parturition-related injury of EUS and EAS using a simulated birth injury (SBI) vaginal distention model. METHODS: EUS and EAS of 3-month-old Sprague-Dawley control and injured rats were fixed in situ, harvested, and microdissected for Ls measurements and assessment of ultrastructure. EUS and EAS function was determined at baseline, and immediately and 4 weeks after SBI, using leak point pressure (LPP) and anorectal manometry (ARM), respectively. Operational L s was compared to species-specific optimal L s using one sample Student's t test. Data (mean ± SD) were compared between groups and time points using repeated measures one-way analysis of variance, followed by Tukey's post hoc pairwise comparisons, with significance set to 0.05. RESULTS: The operational resting Ls of both sphincters (EUS: 2.09 ± 0.07 µm, EAS: 2.02 ± 0.03 µm) was significantly shorter than optimal rat Ls of 2.4 µm. Strains imposed on EUS and EAS during SBI resulted in significant sarcomere elongation and disruption, compared with the controls (EUS: 3.09 ± 0.11 µm, EAS: 3.37 ± 0.09 µm). Paralleling structural changes, LPP and ARM measures were significantly lower immediately (LPP: 21.5 ± 1.0 cmH2 O, ARM: 5.1 ± 2.31 cmH2 O) and 4 weeks (LPP: 27.7 ± 1.3cmH2 O, ARM: 2.5 ± 1.0 cmH2 O) after SBI relative to the baseline (LPP: 43.4 ± 8.5 cmH2 O, ARM: 8.2 ± 2.0 cmH2 O); P < 0.05. CONCLUSIONS: Analogous to humans, the short resting Ls of rat EUS and EAS favors their sphincteric function. The insult experienced by these muscles during parturition leads to sarcomere hyperelongation, myofibrillar disruption, and dysfunction of the sphincters long-term.

Multimodal imaging assessment and histologic correlation of the female rat pelvic floor muscles' anatomy.

Pelvic floor disorders negatively impact millions of women worldwide. Although there is a strong epidemiological association with childbirth, the mechanisms leading to the dysfunction of the integral constituents of the female pelvic floor, including pelvic floor skeletal muscles, are not well understood. This is in part due to the constraints associated with directly probing these muscles, which are located deep in the pelvis. Thus, experimental models and non-invasive techniques are essential for advancing knowledge of various phenotypes of pelvic floor muscle injury and pathogenesis of muscle dysfunction, as well as developing minimally invasive approaches for the delivery of novel therapeutics. The most widely used animal model for pelvic floor disorders is the rat. However, the radiological anatomy of rat pelvic floor muscles has not been described. To remedy this gap, the current study provides the first detailed description of the female rat pelvic floor muscles' radiological appearance on MR and ultrasound images, validated by correlation with gross anatomy and histology. We also demonstrate that ultrasound guidance can be used to target rat pelvic floor muscles for possible interventional therapies.

On triatomines, cockroaches and haemolymphagy under laboratory conditions: new discoveries.

For a long time, haematophagy was considered an obligate condition for triatomines (Hemiptera: Reduviidae) to complete their life cycle. Today, the ability to use haemolymphagy is suggested to represent an important survival strategy for some species, especially those in genus Belminus. As Eratyrus mucronatus and Triatoma boliviana are found with cockroaches in the Blaberinae subfamily in Bolivia, their developmental cycle from egg to adult under a "cockroach diet" was studied. The results suggested that having only cockroach haemolymph as a food source compromised development cycle completion in both species. Compared to a "mouse diet", the cockroach diet increased: (i) the mortality at each nymphal instar; (ii) the number of feedings needed to molt; (iii) the volume of the maximum food intake; and (iv) the time needed to molt. In conclusion, haemolymph could effectively support survival in the field in both species. Nevertheless, under laboratory conditions, the use of haemolymphagy as a survival strategy in the first developmental stages of these species was not supported, as their mortality was very high. Finally, when Triatoma infestans, Rhodnius stali and Panstrongylus rufotuberculatus species were reared on a cockroach diet under similar conditions, all died rather than feeding on cockroaches. These results are discussed in the context of the ecology of each species.

On triatomines, cockroaches and haemolymphagy under laboratory conditions: new discoveries

For a long time, haematophagy was considered an obligate condition for triatomines (Hemiptera: Reduviidae) to complete their life cycle. Today, the ability to use haemolymphagy is suggested to represent an important survival strategy for some species, especially those in genus Belminus. As Eratyrus mucronatus and Triatoma boliviana are found with cockroaches in the Blaberinae subfamily in Bolivia, their developmental cycle from egg to adult under a “cockroach diet” was studied. The results suggested that having only cockroach haemolymph as a food source compromised development cycle completion in both species. Compared to a “mouse diet”, the cockroach diet increased: (i) the mortality at each nymphal instar; (ii) the number of feedings needed to molt; (iii) the volume of the maximum food intake; and (iv) the time needed to molt. In conclusion, haemolymph could effectively support survival in the field in both species. Nevertheless, under laboratory conditions, the use of haemolymphagy as a survival strategy in the first developmental stages of these species was not supported, as their mortality was very high. Finally, when Triatoma infestans, Rhodnius stali and Panstrongylus rufotuberculatus species were reared on a cockroach diet under similar conditions, all died rather than feeding on cockroaches. These results are discussed in the context of the ecology of each species.

Biological cycle and preliminary data on vectorial competence of Triatoma boliviana in laboratory conditions.

With more than 140 potential vectors of Chagas disease, it is important to better know the biology and especially the vectorial capacity of the triatomine species which live in the surroundings of human dwellings. In Bolivia where 17 triatomine species are reported, the principal vector is Triatoma infestans. In some valleys of the department of La Paz where T. infestans is not present, a new species (Triatoma boliviana) was described in 2007. This species lives in a sylvatic environment not far away from the dwellings, and occasionally some individuals are found inside the houses. This study was carried out to describe the biological cycle of T. boliviana and to determine its vectorial competence. The development of a cohort of 95 nymphs of first instar (N1) was followed through nymphal instars and adult stage until death in laboratory (22°C). They were fed twice a week on an immobilized mouse. The median egg-to-adult development time was 8.4 months. The mortality by nymphal instar was lower than 7% except for N1 (67%) and N5 (18%). All nymph instars needed at least two feedings to molt (until six feedings for N5). The differentiation of a nymph into a female or a male could not be detected until the fifth instar for which the food intake was greater for a nymph developing into a female. Adults fed about once a week. The adult life span was around 400 days. The fecundity was 4.2 eggs/female/week, with a hatching rate of 50% and a hatching time of 39 days. In the same conditions, T. infestans showed a similar fecundity but a greater hatching rate and hatching time. A trial for rearing the adults at a higher temperature (26°C) showed a drastic fall in the fecundity and in the hatching rate. The vectorial competence was analyzed for fifth instars and adults by three parameters: the ability to feed on human beings, the capacity to be infected by T. cruzi and the postfeeding defecation delay. Results showed a relatively high vectorial competence: (1) insects fed easily on the tested human being; (2) 100% of the specimens became infected by T. cruzi just by one infected meal; and (3) although the adults defecated after a median postfeeding delay greater than that of T. infestans, results on N5 suggest that they could be as good vectors as T. infestans males.

After five years of chemical control: colonies of the triatomine Eratyrus mucronatus are still present in Bolivia.

Chagas disease, which is caused by the parasite Trypanosoma cruzi, is transmitted to humans by blood-sucking bugs (Triatominae). Eratyrus mucronatus is a well-dispersed triatomine species, found sometimes in dwellings. In the Apolo region of Bolivia, people continue to complain of bites by this bug despite five years of chemical control. For the first time, the domiciliation process of E. mucronatus was evaluated in a zone treated by insecticide, and it was compared with a previous situation 14 years ago. Both an entomological and a serological study were carried out: 152 dwellings were visited and 491 blood samples were analyzed with Stat-Pack and ELISA tests. In 34 dwellings (23% of the total visited dwellings), 160 triatomines of all stages were collected belonging to two species, E. mucronatus (98% of the capture) and Panstrongylus geniculatus. A domiciliation of E. mucronatus is demonstrated, particularly in the peridomicile. Bugs were captured more frequently in bedrooms in the intradomicile, and in curahuas (boundary walls in rammed mud) in the peridomicile. A P. geniculatus adult was found infected with T. cruzi. No evidence of a local vectorial transmission was found. In particular, the limited effect of the insecticide on the presence of E. mucronatus and the role of the curahuas as a source of intrusion/domiciliation process are discussed.

Presence of intradomicile colonies of the triatomine bug Panstrongylus rufotuberculatus in Muñecas, La Paz, Bolivia.

Chagas disease is a tropical parasitic disease endemic to Latin America which affects more than 10 million people, and kills more than 15,000 people each year. This condition, caused by the protozoan parasite Trypanosoma cruzi, is principally transmitted by kissing bugs (Triatominae). In Bolivia, recent reports by the Departmental Health Service showed the presence of Panstrongylus rufotuberculatus in dwellings located in the Charazani Valley (La Paz). A study was then carried out in the area to evaluate the degree of domiciliation of this species, and its possible role in the transmission of Chagas disease. In seven communities, 108 dwellings were visited to actively search for the bugs and 217 people participated in a serological study to determine the prevalence of Chagas disease in the population. Nymphs and adults belonging to two species: Panstrongylus geniculatus (5 insects, 1.5%) and P. rufotuberculatus (344 insects, 98.5%) were collected. One P. rufotuberculatus was captured in a bed, while all the other specimens of this species were found in kitchens in which guinea pigs were being reared. A large bug colony has been encountered in a kitchen environment, with more than 300 specimens of all stages. None of the 201 analyzed bugs was positive for T. cruzi. The seroprevalence of Chagas disease in the human population was low (1.3%); no evidence of a local vectorial transmission was found. In conclusion, for the time being there is no evidence of vectorial transmission of Chagas disease in the region. The possible association between reared guinea pigs and the bugs is discussed. The presence of infected people, the migratory movement of the human population and the relatively high colonization process demonstrate that the region needs to be regularly controlled to prevent the area from becoming a local source of Chagas transmission.

Evaluación de la eficacia de la cloroquina para eltratamiento de la malaria por Plasmodium vivax enYacuiba, Tarija, Bolivia / Evaluation of the chloroquine efficacy for the treatment of malaria by Plasmodium vivax in Yacuiba, Tarija, Bolivia

Se realizó una evaluación in vivo de la eficacia de la cloroquina para el tratamiento de la malaria por Plasmodium vivax, en elsitio centinela de Palmar Chico, Municipio de Yacuiba, Provincia Gran Chaco, Departamento de Tarija al Sur de Bolivia. Fueronincluidos en el estudio 61 pacientes entre 5 y 59 años de edad que presentaban monoinfección por P. vivax. Todos los pacientesrecibieron una dosis total de cloroquina de 25 mg/Kg en 3 días (10mg/Kg el primer día; 7,5 mg/Kg el segundo y tercer días).De acuerdo al protocolo estandarizado de la OPS/OMS, todos los pacientes fueron seguidos por 28 días (controles clínicos yparasitológicos). Se completó el seguimiento de 60 pacientes, ninguno de los pacientes tuvo recurrencias de la parasitemia opresentó manifestaciones clínicas después del tercer día de tratamiento. Este estudio mostró 100% de sensibilidad de P. vivaxa la cloroquina, lo que justifica su permanencia en la política de medicamentos antimaláricos como la droga más adecuada parael tratamiento de las infecciones por P. vivax en el Sur de Bolivia.

We carried out an evaluation in vivoof the chloroquine efficacy for the treatment of malaria by Plasmodium vivax, in the sentinelsite of Palmar Chico, Municipality of Yacuiba, Province Gran Chaco, Department of Tarija to the South of Bolivia. Sixty one patientsaged between 5 and 59 years that presented monoinfection by P. vivaxwere included in the study. All patient received undersupervision a total dose of chloroquine 25mg/kg over three days (10mg/kg on the first day; 7.5 mg/kg on the second and thirddays). According the standardized protocol of the PAHO/WHO, all patients were followed-up for 28 days (clinical and parasitologicalcontrols). Sixty patients completed the follow-up, none of the patients had recurrences of parasitemia or presented clinicalmanifestations after third day of treatment. This study showed 100% of sensibility from P. vivax to chloroquine, what justifies theirpermanency in the antimalarial drug policy as the most adequate drug for the treatment of the P. vivax infections in the South of Bolivia.

Malaria y embarazo: un caso importado de África / Malaria and pregnancy: an imported case from Africa

La malaria es un importante problema de saluden el mundo y es la principal causa de enfermedad ymuerte en muchas zonas tropicales y subtropicales, principalmente en África subsahariana donde las infecciones por Plasmodium falciparum son las másfrecuentes, situación particularmente importante, porque esta especie puede provocar malariagrave e incluso la muerte. Según la OrganizaciónMundial de la Salud se presentan entre 350 a 500millones de casos por año, la gran mayoría enÁfrica subsahariana, donde se registran el 60...