IIET

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

Abstract

Aedes aegypti L. (Diptera: Culicidae) is a mosquito broadly found in tropical and temperate areas of the world. It is the main vector of dengue, chikungunya, zika and yellow fever (urban cycle), among other viruses. Aedes aegypti immatures develop in water holding containers, and frequently use artificial containers in urban settings as larval habitat. Ovitraps are artificial oviposition sites, a tool developed for mosquito population surveillance and to assess effectiveness of control measures. The preference for different oviposition substrate materials was assessed in the field, in two localities of Salta province, northern Argentina, where dengue outbreaks are frequent. The proportion of positive traps did not differ between oviposition substrates. However, higher numbers of eggs were laid in cotton fabric and velour paper, which were better than wooden paddle and blotting paper if the aim was to maximize the numbers of eggs collected. The results also evidenced that substrate preference for oviposition did not differ between geographic regions.

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.