Estratificação vertical da fauna de flebótomos (Diptera, Psychodidae) numa floresta primária de terra firme da Amazônia Central, Estado do Amazonas, Brasil

Vertical stratification of sand fly diversity in relation to natural infections of Leishmania sp. and blood-meal sources in Jamari National Forest, Rondônia State, Brazil

BACKGROUND

Almost 1000 cases of American cutaneous leishmaniasis have been registered yearly in Rondônia State, Brazil. Little is known about the Leishmania transmission cycle (vectors and reservoirs) in the state. This study aimed to evaluate sand fly fauna from two vertical stratification layers in order to identify potential vectors and their blood-meal sources.

METHODS

The study was conducted in Jamari National Forest. Sand flies were collected in the canopy (15 m) and at ground level (1 m) using HP light traps during four months, February, April, August and October, 2018. Insects were identified to the species level, and females were subjected to DNA extraction and PCR targeting minicircle kDNA and hsp70 (for Leishmania detection and species identification), and cytb (to identify blood-meal sources). Exploratory data analysis was used to determine mean of abundance and species richness between stratifications. The hsp70 and cytb sequences were analyzed and compared with sequences from GenBank.

RESULTS

Overall, 68 species were identified from 15,457 individuals. On the Potosi trail, 7531 individuals of 49 species were collected; canopy captures totaled 6463 individuals of 46 species, while ground captures totaled 1068 individuals of 38 species. On the Santa Maria trail, 7926 individuals of 61 species were collected; canopy captures totaled 6136 individuals of 51 species, while ground captures totaled 1790 individuals of 53 species. A total of 23 pools were positive for kDNA (canopy n = 21, ground n = 2). Only two samples were sequenced for hsp70 (both in canopy); one sequence exhibited similarity with Leishmania braziliensis (Lutzomyia davisi pool) and another with L. naiffi (Lu. antunesi pool). The cytb fragment was amplified in 11 of 86 samples. Sample sequencing identified cytb DNA from 5 blood-meal sources: Micrastur gilvicollis, Psophia viridis, Tamandua tetradactyla, Homo sapiens and Choloepus didactylus.

CONCLUSIONS

Sand fly fauna is more diverse in the canopy than at ground level. Factors such as blood-meal sources, resting sites, and abiotic components probably contribute to high abundance in the canopy. Our results reinforce the possibility that Lu. antunesi and Lu. davisi participate in Leishmania transmission in forest environments and may play an important role in transmission from sylvatic to human hosts.

Phlebotominae in peri-domestic and forest environments inhabited by Alouatta caraya in northeastern Argentina

Multiple species of Phlebotominae are vectors of Leishmania (Protozoa: Trypanosomatidae), which causes visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). To describe the Phlebotominae (Diptera: Psychodidae) related to the environments of black and gold howler monkeys Alouatta caraya (Humbodlt, 1812) (Primates: Atelidae), potential vectors were sampled in different landscapes and vertical strata of sleeping trees. Phlebotomine captured between December 2011 and March 2012 (2365 individuals) belonged to eight species, of which Nyssomyia neivai (Pinto, 1926) (61.4%) and Migonemyia migonei (França, 1920) (18.73%) were the most abundant, and Ny. withmani was recorded for the first time in the Chaco province. In the 'peri-domestic' landscape, the phlebotomine were mainly captured in henhouses (78.7%), whereas the tree canopy in 'rural' and 'wild' landscapes yielded 31.2% and 29.1% of the phlebotomine, respectively. A significant association between the type of landscape and the species of phlebotomine was observed by multivariate analysis. Lutzomyia longipalpis (Lutz & Neiva, 1912) and Mg. migonei were associated with 'peri-domestic' landscape, and Ny. neivai was associated with the 'wild' landscape. The results of this prospective study suggest that the interaction between phlebotomine and A. caraya could be a key factor with respect to understanding the epidemiology of leishmaniasis.

On-plot drinking water supplies and health: A systematic review

Many studies have found that household access to water supplies near or within the household plot can reduce the probability of diarrhea, trachoma, and other water-related diseases, and it is generally accepted that on-plot water supplies produce health benefits for households. However, the body of research literature has not been analyzed to weigh the evidence supporting this. A systematic review was conducted to investigate the impacts of on-plot water supplies on diarrhea, trachoma, child growth, and water-related diseases, to further examine the relationship between household health and distance to water source and to assess whether on-plot water supplies generate health gains for households. Studies provide evidence that households with on-plot water supplies experience fewer diarrheal and helminth infections and greater child height. Findings suggest that water-washed (hygiene associated) diseases are more strongly impacted by on-plot water access than waterborne diseases. Few studies analyzed the effects of on-plot water access on quantity of domestic water used, hygiene behavior, and use of multiple water sources, and the lack of evidence for these relationships reveals an important gap in current literature. The review findings indicate that on-plot water access is a useful health indicator and benchmark for the progressive realization of the Sustainable Development Goal target of universal safe water access as well as the human right to safe water.

Sand fly fauna (Diptera: Psychodidae) from the Goytacazes National Forest and surrounding areas of southeastern Brazil

Most studies of the sand fly fauna in southeastern Brazil are conducted in the peridomiciliary environment of leishmaniasis endemic regions. Therefore, to increase the knowledge about diversity and richness of sand fly conservation areas, we describe here the sand fly fauna from the National Forest of Goytacazes (NFG), state of Espírito Santo, Brazil, and its surroundings areas. We also used sand fly fauna records from eight conservations units within the state of Espírito Santo to understand the similarity and relationships among them. The sand flies were simultaneously collected from June, 2008 to May, 2009 in two different environments: a preserved environment represented by the NFG and a modified environment represented by a peridomicile. To establish the similarity among the conservation units, we used a method very similar to parsimony analysis of endemism. We collected 2,466 sand fly specimens belonging to 13 species. Pressatia choti and Nyssomyia intermedia were the most abundant sand fly species. Ny. intermedia is a known vector of Leishmania braziliensis and epidemiological surveillance must be conducted in the area. We discuss aspects regarding the diversity of sand flies as well as the risk of transmission of Leishmania parasites in the area. We also provide for the first time a hypothesis of similarity relationships among conservation units within the state of Espírito Santo.

Comparison between normal saline and a polyelectrolyte solution for fluid resuscitation in severely dehydrated infants with acute diarrhoea

The optimal intravenous solution for rehydration of infants and children with severe dehydration is debated.

AIM

The aim was to compare the efficacy of a polyelectrolyte solution (group PS) with sodium chloride 0.9% solution (group NS) in rapid parenteral rehydration of severely dehydrated infants with acute diarrhoea.

METHODS

Primary outcomes were volume and time to hydration. Secondary outcomes were urea, creatinine, electrolytes, glucose, arterial pH and bicarbonate levels. Patients were assigned randomly and openly to one of the two treatment groups. Severe dehydration was defined as one or more of the following associated with any other sign of dehydration: depressed consciousness, a weak or absent pulse or capillary refill time > 10 sec. Peripheral blood samples for chemical pathology were collected before and after rapid fluid therapy. The mean age of the 36 enrolled infants was 9.1 mths. All had depressed consciousness or severe hypotension/shock. The fluid infusion rate was 50 ml/kg/hr until haemodynamic stability was restored (absence of severe hypotension and two urine emissions). Fluid volume, time to rehydration and weight before and after rehydration were recorded.

RESULTS

All infants recovered full pulse within 1 hr; most had a better level of consciousness or capillary refill <3 sec. Group NS (15 infants) showed (before and after treatment, respectively) a decrease of plasma potassium (3.4 to 3.1 mmol/L, p=0.07), bicarbonate (13.3 to 12.2 mmol/L, p=0.01) and glucose (8.2 to 5.8 mmol/L, p<0.01). Group PS (21 infants) showed a decrease of potassium (4.4 to 3.2 mmol/L, p<0.01) but an increase in bicarbonate (11.6 to 13.3 mmol/L, p<0.01) and glucose (11.4 to 14.8 mmol/L, p=0.08).

CONCLUSION

Polyelectrolyte solution was as effective as normal saline on volume expansion and better for correcting acidosis.

Artificial lighting as a vector attractant and cause of disease diffusion

BACKGROUND

Traditionally, epidemiologists have considered electrification to be a positive factor. In fact, electrification and plumbing are typical initiatives that represent the integration of an isolated population into modern society, ensuring the control of pathogens and promoting public health. Nonetheless, electrification is always accompanied by night lighting that attracts insect vectors and changes people's behavior. Although this may lead to new modes of infection and increased transmission of insect-borne diseases, epidemiologists rarely consider the role of night lighting in their surveys.

OBJECTIVE

We reviewed the epidemiological evidence concerning the role of lighting in the spread of vector-borne diseases to encourage other researchers to consider it in future studies.

DISCUSSION

We present three infectious vector-borne diseases-Chagas, leishmaniasis, and malaria-and discuss evidence that suggests that the use of artificial lighting results in behavioral changes among human populations and changes in the prevalence of vector species and in the modes of transmission.

CONCLUSION

Despite a surprising lack of studies, existing evidence supports our hypothesis that artificial lighting leads to a higher risk of infection from vector-borne diseases. We believe that this is related not only to the simple attraction of traditional vectors to light sources but also to changes in the behavior of both humans and insects that result in new modes of disease transmission. Considering the ongoing expansion of night lighting in developing countries, additional research on this subject is urgently needed.

An update on management of severe acute infectious gastroenteritis in children

This article focuses on clinical and diagnostic aspects relevant to severe acute infectious gastroenteritis in children and will update treatment strategies focused on, although not limited to, anti-infective therapy. For the purposes of this article we will consider severe acute infectious gastroenteritis as follows: watery diarrhea accompanied by, or at high risk for, moderate to severe dehydration due to abrupt onset of vomiting that reduces oral intake, and/or frequent emission of liquid stools, or moderate to severe dysenteric/bloody diarrhea with moderate to high-grade fever. The article will not include food poisoning associated with bacterial toxins and will only briefly discuss oral rehydration strategies and intravenous solutions. The article will also briefly discuss current preventive measures against rotavirus gastroenteritis through vaccination, a topic that has been extensively discussed elsewhere.

Species structure of sand fly (Diptera: Psychodidae) fauna in the Brazilian western Amazon

We surveyed areas of the state of Rondônia in western Amazon for phlebotomine, which are potential vectors of leishmaniasis. A total of 5,998 specimens were captured, resulting in the identification of 48 species within the Lutzomyia (99.98%) and Brumptomyia (0.02%) genera. The predominant species was Lutzomyia davisi, followed by Lutzomyia umbratilis, Lutzomyia llanosmartinsi, Lutzomyia c. carrerai, Lutzomyia dendrophyla, Lutzomyia nevesi and Lutzomyia whitmani. All sand flies identified as vectors for cutaneous leishmaniasis in Brazil, i.e., Lu. davisi, Lu. umbratilis, Lu. c. carrerai and Lu. whitmani, were found in the surveyed areas.

Fauna de flebotomíneos (Diptera: Psychodidae) em um foco de leishmaniose tegumentar americana na área periurbana de Manaus, Estado do Amazonas

No período de agosto de 2001 a julho de 2002, usando armadilhas CDC e Disney, realizaram-se coletas de flebotomíneos, na base de árvores no peridomicílio e nas matas da Comunidade São João, área periurbana de Manaus, Amazonas. Foram capturados 4.104 espécimes, pertencentes a quatro subtribos, 13 gêneros e 49 espécies da subfamília Phlebotominae. Predominou a subtribo Psychodopygina com 3.403 (83%) espécimes, destacando-se Nyssomyia umbratilis, Nyssomyia anduzei, Trichophoromyia eurypyga, Bichromomyia olmeca nociva e Bichromomyia flaviscutellata. O registro de Nyssomyia umbratilis e Nyssomyia anduzei, incriminadas como vetoras de Leishmania (Viannia) guyanensis, e de Bichromomyia flaviscutellata e Bichromomyia olmeca nociva, de Leishmania (Leishmania) amazonensis, indicam risco de infecção para os moradores da área. A grande maioria (98,5%) dos flebotomíneos foi capturada na área de mata. Nyssomyia anduzei e Bichromomyia olmeca nociva foram coletadas no peridomicílio. A riqueza de espécies vetoras de Leishmania nessa área revela a necessidade de uma vigilância entomológica constante.

A hierarchical model for studying risk factors for childhood diarrhoea: a case-control study in a middle-income country

OBJECTIVE

To identify factors associated with diarrhoea occurrence in children in a city in a middle-income country, with high access to water and sanitation.

METHODS

A case-control study in the city of Salvador, north-eastern Brazil was conducted from November 2002 to August 2004. The study population consisted of children presenting at a health facility. A total of 1688 cases of diarrhoea and 1676 controls were selected. Data collection was by a questionnaire and structured observation during home visits. The explanatory variables were grouped according to a conceptual model defined previously. Analysis was done using a hierarchical approach, to provide a more dynamic view of the transmission characteristics of childhood diarrhoea. Non-conditional logistic regression was used, and odds ratio and population-attributable fractions were estimated.

RESULTS

Socioeconomic factors contributed most to determining diarrhoea occurrence, followed by interpersonal contact, while factors related to food preparation, the environment and water and sanitation made a smaller contribution.

CONCLUSION

The findings indicate that the transmission of diarrhoea is influenced by factors from all hierarchical levels, with interpersonal transmission playing a relatively higher role than previously thought. This is compatible with a predominance of viruses and other agents spread by interpersonal routes including Shigella, Giardia and Cryptosporidium. Diarrhoea control strategies in similar settings (middle-income countries in which a large proportion of the population has access to water and sanitation) must give greater emphasis to policies geared towards reducing person-to-person transmission for the prevention of diarrhoea.

Ecosystem approaches and health in Latin America

Important environmental changes that have become increasingly pronounced in the last two centuries and that are seriously affecting human health require the development of integrated and participatory scientific approaches that can result in proposals for institutional and public policy changes. The purpose of this article is to offer some elements that can contribute to a line of reflection based on studies with ecosystem approaches in the Latin America context. The authors begin with a brief description of current scientific literature in public health that links ecosystems and human health in Latin America; next, they describe and compare the two prevailing trends that form the basis for the theoretical and methodological debates on ecosystem approaches; they also review the empirical research in Latin America or concerning Latin American countries in which an ecosystem approach has been adopted. The results point to limited scientific output on the interface between ecosystems and human health; aspects involving public participation and implementation of institutional changes and public policies are still in a rather incipient stage.

Recent observations on the sand fly (Diptera: Psychodidae) fauna of the State of Rondônia, Western Amazônia, Brazil: the importance of Psychdopygus davisi as a vector of zoonotic cutaneous leishmaniasis

Sand flies were collected in the central region of the state of Rondônia (W 64 degrees 30' to 63 degrees 00' and S 10 degrees 00'to 11 degrees 00') using Shannon and CDC light traps from October 1997 to August 2000. A total of 85,850 specimens representing 78 named species were captured. Of these 14 were new records for Rondônia. The proportion of males/females was 1/1.131. Trypanosomatids, that are presently being identified, were detected in 11 species. Leishmania (Viannia) naiffi was recorded from Psychodopygus davisi and P. hirsutus. In the present study the dominant species was P. davisi (39.6%) followed by Lutzomyia whitmani (13.1%), P. carrerai (11.6%), and P. hirsutus (10.2%). The importance of P. davisi as a vector of zoonotic cutaneous leishmaniasis is discussed.