Limited diversity of Anopheles darlingi in the Peruvian Amazon region of Iquitos.

Anopheles darlingi is the most important malaria vector in the Amazon basin of South America, and is capable of transmitting both Plasmodium falciparum and P. vivax. To understand the genetic structure of this vector in the Amazonian region of Peru, a simple polymerase chain reaction (PCR)-based test to identify this species of mosquito was used. A random amplified polymorphic DNA-PCR was used to study genetic variation at the micro-geographic level in nine geographically separate populations of An. darlingi collected in areas with different degrees of deforestation surrounding the city of Iquitos. Within-population genetic diversity in nine populations, as quantified by the expected heterozygosity (H(E)), ranged from 0.27 to 0.32. Average genetic distance (F(ST)) among these populations was 0.017. These results show that the nine studied populations are highly homogeneous, suggesting that strategies can be developed to combat this malaria vector as a single epidemiologic unit

Perfiles hematológicos en pacientes infectados con malaria en un área endémica del Perú [Hematological profiles of malaria-infected patients in an endemic area of Peru]

OBJECTIVES.: To evaluate the variation of hematological profiles of patients infected with uncomplicated Plasmodium vivax (Pv) and P. falciparum (Pf) malaria before, during and after treatment in a population of the Loreto region. MATERIALS AND METHODS.: This study was conducted between 2010 and 2012, in Zungarococha (Iquitos). The 425 participants had three visits (visit 1-day 0-before treatment, visit 2-day 7-during treatment, visit 3-day 28-after treatment), complete blood count, microscopic and molecular diagnosis (PCR). RESULTS.: At the first visit, 93 (21.9%) participants were found positive for Pv and 34 (8.0%) for Pf. All positives showed a reduction in hematocrit, white blood cell count (WBC), ablated and segmented neutrophils, eosinophils and platelets (p<0.001) compared to the negative group. A higher percentage of ablated neutrophils was found in Pf and segmented neutrophils in Pv compared to the negative group. Variations in hematological profiles were observed after treatment for both species; ablated neutrophils decreased, platelets increased, eosinophils increased at day 7 and declined at day 28, hematocrit and segmented neutrophils decreased at day 7 and normalized at day 28. Interspecies differences over time showed a bigger daily decrease in ablated neutrophils in Pv-infected when compared to Pf. CONCLUSIONS.: The hematological profile in uncomplicated malaria-positive patients varies over time during and after treatment. These are indicators of disease progression and help in the therapeutic surveillance of Plasmodium-infected patients

A cross-sectional study of seroprevalence of strongyloidiasis in pregnant women (peruvian Amazon basin)

Strongyloidiasis is a soil-transmitted helminthiasis with a high global prevalence. Objectives: We aimed to evaluate the prevalence of Strongyloides stercoralis infection and assess strongyloidiasis serology as a screening technique in the Peruvian Amazon. Material and Methods: We performed a cross-sectional study of strongyloidiasis in 300 pregnant women in Iquitos (Peru) from 1 May 2019 to 15 June 2019. Women were tested using serology (Strongyloides IgG IVD-ELISA kit) as an index test and the modified Baermann technique and/or charcoal fecal culture as the parasitological reference standard. Results: The reference tests showed S. stercoralis in the stool of 30 women (prevalence: 10%; 95% confidence interval [CI] 7.1% to 13.9%), while 101 women tested positive on the blood test (prevalence: 33.7%; 95% CI 28.6% to 39.4%). Fourteen of the 15 women (93.3%) with positive results according to the modified Baermann technique, and 14 of the 23 women (56.5%) with positive charcoal cultures also had positive serological results. Serology showed a sensitivity of 63.3% and a negative predictive value of 94.4%. Conclusion: In Iquitos, pregnant women have a high prevalence of S stercoralis. S. stercoralis ELISA could be an excellent tool for population-based screening, as it has a high negative predictive value that can help to rule out the presence of active infectionThis research was co-funded by the University Development Cooperation Program, Miguel Hernández University of Elche and Generalitat Valenciana. Grant number [SOLCIF/2017/0005

Evaluation of excreted-secreted antigens of L. (L.) amazonensis, L. (V.) braziliensis and L. (L.) chagasi in immunodiagnosis of human and dog Visceral leishmaniasis.

A Leishmaniose visceral é um problema que cresce no Estado de São Paulo afetando o homem e o cão. Os exoantígenos da membrana das leishmanias são liberados no meio de cultura. Os exoantígenos são importantes na indução da imunidade mediada pelas células T e B estimulando a produção elevada de anticorpos. Realizamos uma avaliação comparativa por ELISA e Immunoblotting de exoantígenos e antígenos totais de L. (L.) amazonensis, L. (V.) braziliensis e L. (L.) chagasi, no diagnóstico da leishmaniose visceral humana e canina. Obteve-se por ELISA sensibilidade de 100% para ambos os preparados antigênicos independente da espécie de Leishmania. A melhor especificidade em humanos e cães foi com os exoantígenos. O exoantígeno da L. (L.) chagasi teve a melhor especificidade e média de absorbâncias comparadas aos das outras espécies (p<0.005). Para o hospedeiro humano o ELISA com exoantígenos, não discriminou pacientes com leishmaniose cutânea e ou mucocutânea. O Immublotting dos exoantígenos de L. (L.) chagasi (IBleish) apresentou 100% de sensibilidade e especificidade para os cães. Os dados do IBleish-L. (L.) chagasi demonstraram a possibilidade de sua utilização como método confiável para a confirmação do diagnóstico da leishmaniose canina.The visceral leishmaniasis is a new problem that grows in the State of São Paulo, affecting men and dogs. The exoantigens from the membrane of the Leishmania, are released out of culture medium. The exoantigens are important in the induction of immunity mediated by T and B cells, stimulating the production of antibodies. This work was carried out an evaluation of ELISA and Immunoblotting using comparatively exoantigens and total antigens of L. (L.) amazonensis, L. (V.) braziliensis and L. (L.) chagasi for the diagnosis of canine and human visceral leishmaniasis. ELISA sensitivity was 100% for all different antigens, independent of the species of Leishmania employed. The best specificity for both human and dogs were obtained with exoantigens. Exoantigen from L. (L.) chagasi was what showed the best specificity and mean absorbance compared to those of other species (p<0.05). The ELISA with exoantigens for the human host not discriminate individuals with leishmaniasis cutaneous or mucocutaneous. The Immunoblotting that used the exoantigens of L. (L.) chagasi (IBleish) showed 100% sensitivity and specificity for the dogs. The IBleish-L. (L.) chagasi showed the possibility of its use as a reliable method to confirm the diagnosis of canine leishmaniasis

IgG subclass responses to excreted-secreted antigens of Plasmodium falciparum in a low-transmission malaria area of the Peruvian Amazon

Abstract Background Malaria in Peru is concentrated in the Amazon region, especially in Loreto, and transmission is focused in rural and peri-urban communities. The government has approved a malaria elimination plan with a community approach and seeks to reduce the risk of transmission through preventive interventions, but asymptomatic and low-parasite-density infections are challenges for disease control and elimination. IgG antibodies play a critical role in combating infection through their ability to reduce parasitaemia and clinical symptoms. In particular, IgG subclasses have important roles in controlling malaria disease and may provide new insight into the development of malaria control strategies and understanding of malaria transmission. Through the use of excreted-secreted antigens from Plasmodium falciparum, were evaluated the responses of the four IgG subclasses in symptomatic and asymptomatic malarial infections. Results Higher levels of whole IgG were observed in asymptomatic carriers (P < 0.05). IgG3 and IgG1 were the most prevalent subclasses and did not show differences in their antibody levels in either type of carrier. All symptomatic carriers were positive for IgG4, and the presence of IgG3 and IgG2 were correlated with protection against parasitaemia. IgG2 showed lower prevalence and antibody titers in comparison to other subclasses. Conclusions This is the first study that characterizes the IgG subclass response in the Peruvian Amazon, and these results show that even in populations from regions with low malaria transmission, a certain degree of naturally acquired immunity can develop when the right antibody subclasses are produced. This provides important insight into the potential mechanisms regulating protective immunity

The effect of deforestation on the human-biting rate of Anopheles darlingi, the primary vector of falciparum malaria in the Peruvian Amazon

To examine the impact of tropical rain-forest destruction on malaria, we conducted a year-long study of the rates at which the primary malaria vector in the Amazon, Anopheles darlingi, fed on humans in areas with varying degrees of ecological alteration in the Peruvian Amazon. Mosquitoes were collected by human biting catches along the Iquitos-Nauta road at sites selected for type of vegetation and controlled for human presence. Deforested sites had an A. darlingi biting rate that was more than 278 times higher than the rate determined for areas that were predominantly forested. Our results indicate that A. darlingi displays significantly increased human-biting activity in areas that have undergone deforestation and development associated with road development. Copyright © 2006 by The American Society of Tropical Medicine and Hygiene

Clinical and Metagenomic Characterization of Neurological Infections of People With Human Immunodeficiency Virus in the Peruvian Amazon.

BACKGROUND: Neurological opportunistic infections cause significant morbidity and mortality in people with human immunodeficiency virus (HIV) but are difficult to diagnose. METHODS: One hundred forty people with HIV with acute neurological symptoms from Iquitos, Peru, were evaluated for cerebral toxoplasmosis with quantitative polymerase chain reaction (qPCR) of cerebrospinal fluid (CSF) and for cryptococcal meningitis with cryptococcal antigen test (CrAg) in serum or CSF. Differences between groups were assessed with standard statistical methods. A subset of samples was evaluated by metagenomic next-generation sequencing (mNGS) of CSF to compare standard diagnostics and identify additional diagnoses. RESULTS: Twenty-seven participants were diagnosed with cerebral toxoplasmosis by qPCR and 13 with cryptococcal meningitis by CrAg. Compared to participants without cerebral toxoplasmosis, abnormal Glasgow Coma Scale score (P = .05), unilateral focal motor signs (P = .01), positive Babinski reflex (P = .01), and multiple lesions on head computed tomography (CT) (P = .002) were associated with cerebral toxoplasmosis. Photophobia (P = .03) and absence of lesions on head CT (P = .02) were associated with cryptococcal meningitis. mNGS of 42 samples identified 8 cases of cerebral toxoplasmosis, 7 cases of cryptococcal meningitis, 5 possible cases of tuberculous meningitis, and incidental detections of hepatitis B virus (n = 1) and pegivirus (n = 1). mNGS had a positive percentage agreement of 71% and a negative percentage agreement of 91% with qPCR for T gondii. mNGS had a sensitivity of 78% and specificity of 100% for Cryptococcus diagnosis. CONCLUSIONS: An infection was diagnosed by any method in only 34% of participants, demonstrating the challenges of diagnosing neurological opportunistic infections in this population and highlighting the need for broader, more sensitive diagnostic tests for central nervous system infections

Targeted screening strategies to detect Trypanosoma cruzi infection in children.

Millions of people are infected with Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. Anti-trypanosomal drug therapy can cure infected individuals, but treatment efficacy is highest early in infection. Vector control campaigns disrupt transmission of T. cruzi, but without timely diagnosis, children infected prior to vector control often miss the window of opportunity for effective chemotherapy.We performed a serological survey in children 2-18 years old living in a peri-urban community of Arequipa, Peru, and linked the results to entomologic, spatial and census data gathered during a vector control campaign. 23 of 433 (5.3% [95% CI 3.4-7.9]) children were confirmed seropositive for T. cruzi infection by two methods. Spatial analysis revealed that households with infected children were very tightly clustered within looser clusters of households with parasite-infected vectors. Bayesian hierarchical mixed models, which controlled for clustering of infection, showed that a child's risk of being seropositive increased by 20% per year of age and 4% per vector captured within the child's house. Receiver operator characteristic (ROC) plots of best-fit models suggest that more than 83% of infected children could be identified while testing only 22% of eligible children.We found evidence of spatially-focal vector-borne T. cruzi transmission in peri-urban Arequipa. Ongoing vector control campaigns, in addition to preventing further parasite transmission, facilitate the collection of data essential to identifying children at high risk of T. cruzi infection. Targeted screening strategies could make integration of diagnosis and treatment of children into Chagas disease control programs feasible in lower-resource settings