Prevalence of helmintic infections in Brazilian Maxakali indigenous: a repeated cross-sectional design

BACKGROUND

The prevalence of intestinal parasites is known to be high among Amerindian populations; further, there are serious problems in the healthcare of these populations in Brazil. The Maxakali, located in the northeastern region of Minas Gerais, Brazil, is an indigenous group that still preserves many of its cultural aspects. This study aimed to compare the positivity rate of schistosomiasis and soil-transmitted helminths in this ethnic group in epidemiological surveys conducted in 1972 and 2014.

METHODS

Stool parasitological examinations were performed by the Kato-Katz technique during both periods in this population. In 2014, the parasitological diagnosis was also realized with the TF-Test® technique.

RESULTS

In 1972, 270 inhabitants were examined. The positivity rates were 67.4% for Schistosoma mansoni, 72.9% for hookworms, 43.7% for Ascaris lumbricoides, and 23.7% for Trichuris trichiura. In 2014, 545 individuals were examined, and the positivity rates obtained were 45.7% for S. mansoni, 22.8% for hookworms, 0.6% for A. lumbricoides, and 2.8% for T. trichiura.

CONCLUSIONS

The comparison of the parasitological surveys conducted in 1972 and 2014, indicates that the indigenous Maxakali remained neglected by the health and indigenous protection authorities during these four decades. The infection rate observed in 2014 for schistosomiasis and hookworm remains high, considering the current epidemiological view of these diseases in the Brazilian population.

Prevalence of schistosomiasis mansoni in indigenous Maxakali villages, Minas Gerais, Brazil

Intestinal parasitic infections are a common health problem among Amerindian populations and schistosomiasis represents one of the most prevalent diseases in Maxakali people. The Kato-Katz is the diagnostic method recommended by WHO for epidemiological studies; however, one of the technique's limitations is the failure to detect parasites in individuals with low parasite load. The aim of this study was to establish the prevalence of Schistosoma mansoni in indigenous Maxakali villages, evaluating the TF-Test® performance for diagnosis compared to the Kato-Katz technique. Stool samples from 545 individuals were processed by the TF-Test® (1 sample) and Kato-Katz (1 slide). The positivity rate for S. mansoni by Kato-Katz was 45.7%. The rate by the TF-Test® was 33.2%, and 51.9% by the combined parasitological techniques. The amplitude of parasite load was 24 to 4,056 eggs per gram of feces (epg), with a geometric mean of 139 epg. The co-positivity, co-negativity, and accuracy values by TF-Test® in relation to Kato-Katz were 59.0%, 88.5%, and 75.0%, respectively. The agreement between these techniques was moderate (k=0.486) as determined by the kappa index. Thus, the results of this study demonstrated that the performance of Kato-Katz was superior (p <0.05) to that of TF-Test® in the detection of S. mansoni. The combination of TF-Test® and Kato-Katz resulted in an increased positivity rate of S. mansoni, demonstrating the high risk of infection to which indigenous populations are exposed and the importance of the implementation of control strategies in Maxakali villages.

[Control of visceral leishmaniasis in the town of Porteirinha, state of Minas Gerais, Brazil, from 1998 to 2003]

INTRODUCTION

In the town of Porteirinha, State of Minas Gerais, 23 human cases of visceral leishmaniasis (VL) in 1998 and 1999 were recorded.

METHODS

A study was conducted involving the triad of action recommended for the control of VL. Patients were treated and serologically positive dogs were euthanized quarterly. The pyrethroid insecticide α-cypermethrin was applied in the neighborhoods where human cases were recorded.

RESULTS

A reduction in canine seroprevalence and sand flies occurred following the implementation of control measures, reflecting in a reduction in human cases of VL.

CONCLUSIONS

The results show the efficiency of such control measures when used in association.

Flebotomíneos (Diptera: Psychodidae) de um foco de leishmaniose tegumentar no Estado de Minas Gerais

Na localidade do Brejo do Mutambal, situado no município de Varzelândia (MG), área endêmica para leishmaniose tegumentar, foram realizadas capturas mensais sistemáticas utilizando-se armadilhas luminosas do tipo CDC durante o período de janeiro a dezembro de 2000. Foram capturadas 19 espécies de flebotomíneos, totalizando 6.756 exemplares. Lutzomyia intermedia (5,1%), L. migonei (0,4%) e L. whitmani (0,1%), relacionadas com a transmissão de leishmaniose tegumentar, foram capturadas em número reduzido. Lutzomyia longipalpis foi a espécie predominante (34,8%), sugerindo também um risco de transmissão da leishmaniose visceral. A proporção de insetos capturados no peridomícilio foi de 91,7% enquanto no intradomicílio foi de 8,3%. A interferência de fatores climáticos (temperatura, umidade relativa do ar e pluviosidade) sobre a dinâmica populacional de flebotomíneos foi avaliada.

Aspectos da ecologia e do comportamento de flebotomíneos em área endêmica de leishmaniose visceral, Minas Gerais

O comportamento e hábitos alimentares de algumas espécies da flebotomíneos têm sido útil na compreensão da epidemiologia das leishmanioses. No município de Porteirinha (MG), foram realizadas capturas mensais sistematizadas utilizando-se 28 armadilhas luminosas tipo CDC, durante o período de janeiro a dezembro de 2002. Foram capturadas 14 espécies de flebotomíneos, totalizando 1.408 exemplares. De acordo com o ambiente, os resultados obtidos mostraram que o peridomicílio apresentou a maior (53,3%) porcentagem dos espécimens encontrados na região, embora parte (46,7%) da fauna também tenha sido encontrada no intradomicílio. O repasto sanguíneo de 38 fêmeas de Lutzomyia longipalpis, provenientes do campo, foi identificado através da reação de precipitina. Os resultados indicam que Lutzomyia longipalpis foi a espécie predominante (65,1%), mostrando-se oportunista, podendo sugar uma ampla variedade de vertebrados.

Phlebotomine sand flies in Porteirinha, an area of American visceral leishmaniasis transmission in the State of Minas Gerais, Brazil

A study of the phlebotomine sand fly fauna was carried out in an endemic area of American visceral leishmaniasis (AVL) in the municipality of Porteirinha, in the Brazilian state of Minas Gerais. Captures were performed with CDC light traps in 7 districts, 5 days per month, during 2 consecutive years (January 2000 to December 2001). A total of 3240 sand flies were captured and identified. Sixteen species were found, among which 15 belonged to the genus Lutzomyia and one to the genus Brumptomyia. Lutzomyia longipalpis, a proven vector of AVL, was the predominant species (71.85%) throughout the time period. The interference of climatic factors (temperature, humidity, and rainfall) over the populational dynamics of the sand flies was determined. Statistical analysis of the data showed a significant correlation among the number of phlebotomine sand flies collected, rainfall, and humidity, whereas the effect of temperature was negligible, in that particular region. The amount of collected phlebotomine, the number of human cases, and the prevalence of canine AVL in the districts of Porteirinha are discussed.