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Inflammatory responses and intestinal injury development during acute trypanosoma cruzi infection are associated with the parasite load

Parasites and Vectors -

Background: Chagas disease is caused by the protozoan Trypanosoma cruzi and is characterized by cardiac, gastrointestinal, and nervous system disorders. Although much about the pathophysiological process of Chagas disease is already known, the influence of the parasite burden on the inflammatory process and disease progression remains uncertain. Methods: We used an acute experimental disease model to evaluate the effect of T. cruzi on intestinal lesions and assessed correlations between parasite load and inflammation and intestinal injury at 7 and 14 days post-infection. Low (3 × 102), medium (3 × 103), and high (3 × 104) parasite loads were generated by infecting C57BL/6 mice with “Y”-strain trypomastigotes. Statistical analysis was performed using analysis of variance with Tukey’s multiple comparison post-test, Kruskal–Wallis test with Dunn’s multiple comparison, χ2 test and Spearman correlation. Results: High parasite load-bearing mice more rapidly and strongly developed parasitemia. Increased colon width, inflammatory infiltration, myositis, periganglionitis, ganglionitis, pro-inflammatory cytokines (e.g., TNF-α, INF-γ, IL-2, IL-17, IL-6), and intestinal amastigote nests were more pronounced in high parasite load-bearing animals. These results were remarkable because a positive correlation was observed between parasite load, inflammatory infiltrate, amastigote nests, and investigated cytokines. Conclusions: These experimental data support the idea that the parasite load considerably influences the T. cruzi-induced intestinal inflammatory response and contributes to the development of the digestive form of the disease.

Toscana virus isolated from sandflies, Morocco

Parasites and Vectors -

To investigate the transmission of phleboviruses, a total of 7,057 sandflies were collected in well-known foci of cutaneous leishmaniasis and were identified to species level according to morphological characters.Collected sandflies were tested by Nested PCR for the presence of Phleboviruses and subsequently by viral isolation on Vero cells. The corresponding products were sequenced. Toscana virus was isolated, for the first time, from 5 pools of sandflies.Hence, Toscana virus should be considered a potential risk that threatens public health and clinicians should be aware of the role of Toscana virus in cases of meningitis and encephalitis in Morocco.

Efficacy of a fixed combination of permethrin 54.5% and fipronil 6.1% (Effitix®) in dogs experimentally infested with Ixodes ricinus

Parasites and Vectors -

Background: Ticks are the most important vectors of disease-causing pathogens in domestic animals and are considered to be second worldwide to mosquitoes as vectors of human diseases. In Europe, Ixodes ricinus, the sheep tick, plays an important role as companion animal parasite but is also the primary vector of medically important diseases such as tick-borne encephalitis and Lyme borreliosis.The present study was designed to evaluate the efficacy under laboratory conditions of a new fixed spot-on combination of fipronil and permethrin (Effitix®, Virbac) in treating and preventing tick infestations of Ixodes ricinus in dogs. Methods: Twelve dogs were included in this randomized, controlled, blinded laboratory study. They were randomly allocated to two groups of six dogs each according to their pre-treatment live attached Ixodes ricinus tick count. On day 0, the dogs from Group 2 were treated with the recommended dose of Effitix®, the dogs from Group 1 remained untreated. On days −2, 7, 14, 21, 28 and 35, all dogs were infested with 50 (±4) viable unfed adult Ixodes ricinus (20 ± 2 males, 30 ± 2 females). Ticks were removed and counted at 48 ± 2 hours post product administration or tick infestations. Results: Through the study, the tick attachment rates for the untreated group were greater than 25% demonstrating that adequate levels of infestation were reached on the control dogs. Based on both arithmetic and geometric means (AM and GM), Effitix® was deemed to be effective against Ixodes ricinus on days 2, 9, 16, 23, 30 and 37 with a percentage of efficacy of 98%, 100%, 100%, 100%, 93% and 95% respectively (AM). No clinical abnormalities were detected during the study. Conclusions: The study has shown under laboratory conditions, that Effitix® is a safe and an effective combination to treat and protect dogs from Ixodes ricinus up to 37 days after administration. The high immediate efficacy of 98% evaluated at 48 hours post-treatment was particularly interesting, meaning that Effitix has a curative effect against ticks (Ixodes ricinus) and provides a rapid control of existing Ixodes ricinus infestation on a dog at the time of treatment.

The impact of different sprayable surfaces on the effectiveness of indoor residual spraying using a micro encapsulated formulation of lambda-cyhalothrin against Anopheles gambiae s.s.

Parasites and Vectors -

Background: The type of sprayable surface impacts on residual efficacy of insecticide used in indoor residual spraying (IRS). However, there is limited data on common types of wall surfaces sprayed in Zanzibar and mainland Tanzania where IRS began in 2006 and 2007 respectively. The study investigated residual efficacy of micro-encapsulated lambda-cyhalothrin sprayed on common surfaces of human dwellings and domestic animal shelters in Zanzibar and mainland Tanzania. Methods: An experimental hut was constructed with different types of materials simulating common sprayable surfaces in Zanzibar and mainland Tanzania. Surfaces included cement plastered wall, mud-daub, white-wash, wood, palm-thatch, galvanized iron-sheets, burnt-bricks, limestone and oil-paint. The World Health Organization (WHO) procedure for IRS was used to spray lambda-cyhalothrin on surfaces at the dose of 20–25 mg/m2. Residual efficacy of insecticide was monitored through cone bioassay using laboratory-reared mosquitoes; Kisumu strain (R–70) of Anopheles gambiae ss. Cone bioassay was done every fortnight for a period of 152 days. The WHO Pesticide Evaluation Scheme (WHOPES) threshold (80% mortality) was used as cut-off point for acceptable residual efficacy. Results: A total of 5,800 mosquitos were subjected to contact cone bioassay to test residual efficacy of lambda-cyhalothrin. There was a statistically significant variation in residual efficacy between the different types of wall surfaces (r = 0.24; p < 0.001). Residual efficacy decreased with increasing pH of the substrate (r = −0.5; p < 0.001). Based on WHOPES standards, shorter residual efficacy (42-56days) was found in wall substrates made of cement, limestone, mud-daub, oil paint and white wash. Burnt bricks retained the residual efficacy up to 134 days while galvanized iron sheets, palm thatch and wood retained the recommended residual efficacy beyond 152 days. Conclusion: The study revealed a wide variation in residual efficacy of micro encapsulated formulation of lambda-cyhalothrin across the different types of wall surfaces studied. In areas where malaria transmission is bimodal and wall surfaces with short residual efficacy comprise > 20% of sprayable structures, two rounds of IRS using lambda-cyhalothrin should be considered. Further studies are required to investigate the impact of sprayable surfaces on residual efficacy of other insecticides commonly used for IRS in Zanzibar and mainland Tanzania.

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