Leishmaniasis

Leishmaniasis

Fecha: 
16/11/2018
Linea de Investigacion: 

Abstract

Background

Some sand flies are of medical importance because they are vectors of Leishmania parasites that are responsible for leishmaniasis. The aim of this study was to make a retrospective epidemiological analysis of tegumentary leishmaniasis (TL), to identify Leishmania spp. from patient isolates and to describe the diversity of sand flies from a border area between Bolivia and Argentina.

Methods

TL cases included in the study were diagnosed in an endemic area of the north of Argentina from 1985 to 2017. The parasites isolated were characterized by the cytochrome B method. Sandflies were captured with Centers for Disease Control traps in Aguas Blancas and Media Luna-Algarrobito localities.

Results

A total of 118 cases of TL were analysed. Eight isolates were characterized as Leishmania (Viannia) braziliensis. A total of 1291 sandflies were captured, including Nyssomyia neivai, Cortelezzii complex, Evandromyia sallesiMigonemyia migonei and Micropygomyia quinquefer. Within the area, sandflies were found in the backyards of houses.

Conclusions

In this region there exists the possibility of peridomestic transmission of TL in the neighbourhoods peripheral to the urban area and in rural environments as well as the risk of transmission to travellers that pass through the customs offices.

Fecha: 
25/09/2018
Linea de Investigacion: 

Cutaneous leishmaniasis is endemic in Salta province, which belongs to the northwest of Argentina. Leishmania spp. DNA from Giemsa-stained slides of up to 12 years in storage of patients from Salta was characterized through PCR-restriction fragment length polymorphism. One hundred smears positive for microscopy, classified in a semiquantitative scale for amastigote density, were analyzed. Also, Leishmanin skin test (LST) results were included. DNA extraction was carried out applying lysis buffer with proteinase K, and then DNA was amplified with ribosomal internal transcribed spacer 1 primers. PCR products were digested with HaeIII enzyme. All PCR-positive smears (74/100) belonged to Viannia subgenus. A statistically significant, directly proportional relationship between semiquantitative microscopy and PCR results was detected. All patients had LST-positive results (induration ≥ 5 mm), and the smears of those with smaller induration (LST < 19 mm) gave a higher proportion of positive PCR results. This study determined that smear age did not affect PCR positivity, which allows retrospective analyzes and suggests smears might be useful for molecular complementary diagnosis. Because Leishmania (Viannia) braziliensis is the main circulating species in the study area, determining Viannia subgenus in all analyzed samples confirms previous findings. PCR positivity showed statistically significant differences according to semiquantitative microscopy, highlighting the importance of parasite burden in the diagnostic sensitivity of the method. Considering that smears of patients with smaller LST induration were more positive in PCR, a negative smear from patients with positive LST response, but < 19 mm, could actually represent a false-negative result.

 

© The American Society of Tropical Medicine and Hygiene

Fecha: 
03/08/2018
Linea de Investigacion: 

Abstract

The sand fly fauna in Hipólito Yrigoyen, Argentina, a locality where cutaneous leishmaniasis cases occur, was surveyed with zones of higher abundance of sand flies correlated to vegetation cover estimated through normalized difference vegetation index (NDVI). Sand flies were collected with 10 CDC traps during six nights, from December 2009 to January 2010. A map was built of expected sand flies abundance in which levels of NDVI were categorized. In total, 1,392 Phlebotominae (Diptera: Psychodidae) specimens were collected, comprised of the following species: Nyssomyia neivai (Pinto 1926), Migonemyia migonei (França 1920), species of the cortelezzii complex (Brèthes 1923), Evandromyia sallesi (Galvão & Coutinho 1940), and Psathyromyia shannoni (Dyar 1929). Positive correlations were found between the abundance of sand flies and the NDVI (P < 0.05) for buffer areas of <150 m radii from the trap location points, i.e., the sand fly abundance was greater where vegetation cover and density were greater. In this context, plant cover should be taken into account to prioritize surveillance and control areas within the program of sand flies control in northern Argentina.

Fecha: 
05/10/2017
Linea de Investigacion: 

Abstract

Leishmania (Viannia) braziliensis is the species most frequently implicated with cutaneous and mucosal leishmaniasis in the Americas; its diagnosis is based on the identification of amastigotes in lesions, which is limited by low parasite burden. Leishmanin Skin Test (LST) is a support tool for diagnosis, based on delayed type hypersensitivity responses to Leishmania antigens injected intradermally, used in endemic areas as a complement to diagnosis. A retrospective analysis of individuals evaluated for their first episode of tegumentary leishmaniasis at a reference center in Argentina during the period 2006–2015 was performed, with the goal of assessing its usefulness as a support tool in the diagnosis of leishmaniasis. Demographic, clinical and diagnostic work-up were analyzed in individuals with clinically compatible lesions, lesion`s smear and LST. A total of 733 cases that met the case definition were included in the analysis; 678 (93%) localized cutaneous cases, 50 (7%) with mucosal involvement and 5 (<1%) disseminated. Diagnostic confirmation was reached in 474 (65%) cases through positive smears from skin or mucosal lesions, with only 6 cases among this group having negative LST. Among smear negative cases, 190 were negative also by LST, but in 69 instances LST was positive. Across age groups, similar ratios of sensitivity between smear and LST were calculated. Lesions older than 21 days-old were found to correlate with positive results both for smear and LST significantly more than younger lesions. These findings support the clinical use of LST as a diagnostic complement for American Cutaneous Leishmaniasis across all age groups even in endemic areas. In this analysis, the correlation with smear was high. Standardization of this technique and further research into its most adequate preparation and utilization protocols across different sites will help in the management of suspicious clinical cases.

Autor/es: 
Fecha: 
01/01/2016
Linea de Investigacion: 

Abstract

Background. Endemic areas of tegumentary leishmaniasis (TL) in Salta, Argentina, present some overlap zones with the geographical distribution of Chagas disease, with mixed infection cases being often detected. Objectives. The purpose of this study was to determine the magnitude of Leishmania sp. infection and potential associated risk factors, the serologic prevalence of T. cruzi, and the presence of T. cruzi-Leishmania sp. mixed infection in a region of the northwest of Argentina. Methods. Cross-sectional studies were conducted to detect TL prevalence and T. cruzi seroprevalence. A case-control study was conducted to examine leishmaniasis risk factors. Results. Prevalence of TL was 0.17%, seroprevalence of T. cruzi infection was 9.73%, and mixed infection proportion-within the leishmaniasic patients group-was 16.67%. The risk factors associated with TL transmission were sex, age, exposure to bites at work, staying outdoors more than 10 hours/day, bathing in the river, and living with people who had lesions or were infected during the study. Discussion. The endemic pattern of TL seems to involve exposure of patients to vectors in wild as well as peridomestic environment. Cases of T. cruzi infection are apparently due to migration. Therefore, a careful epidemiological surveillance is necessary due to the contraindication of antimonial administration to chagasic patients.

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