Strongyloides venezuelensis infection augments arterial blood pressure in male wistar rats

Strongyloidiasis is an intestinal parasitosis that occurs in humans infected by Strongyloides stercoralis mostly. At its acute phase, symptoms like constipation, diarrhea and abdominal pain can be observed, but become asymptomatic for a long time, until an immunosuppression will start a hyperinfection and the dissemination of the disease, prevalent on the elderly population in tropical countries. Ivermectina treatment is the currently choice for this disease, due to its great efficacy and the results reported. It is expected that around one hundred million individuals have been infected around the world. Strongyloides venezuelensis is an intestinal helminth utilized on Strongyloidiasis investigations, in rodents. As the parasites reach the blood stream after subcutaneous infection, the larvae migrate to the lung by systemic circulation, but the effects of S. venezuelensis in the circulation remain widely unknown. Moreover, the role played by S. venezuelensis in the cardiovascular function has been understudied. Thus, the aim of this study is to determine whether acute infection with S. venezuelensis alters systemic blood pressure or not. Male wistar rats were infected subcutaneously with 2000 L3 larvae of S. venezuelensis and monitored during 21 days (Infected group), compared to a Healthy group, no infected. Oviposition, body and faeces weight, water and food intake were determined every 3 days. Moreover, systemic blood pressure was assessed by tail cuff plethysmography. At the end of experiments, the animals were euthanized and the number of worms, ventricles, lung and thymus and small intestine weight were registered. It was possible to observe that systolic blood pressure (126.86 ± 2.74 vs 155.08 ± 7.61 at 9°-day post infection - dpi - and 134.44 ± 5.22 vs 157.77 ± 9.55 at 21° dpi) and mean arterial pressure (71.72 ± 1.59 vs 80.51 ± 2.32 at 21° dpi) were markedly higher (P <  0.001) in infected group in comparison to the Healthy group. Those changes occurred after larvae passes through the circulation and demonstrated a late response to the presence of this parasite. These results suggest that host circulatory system reacts to this infection resulting in a significant increase in blood pressure.

Evaluation of gastrointestinal transit after infection with different loads of Strongyloides venezuelensis in rats

The aim was to correlate the gastrointestinal transit profile in rats, evaluated by a biomagnetic technique, in response to infection with different loads of Strongyloides venezuelensis. Eggs per gram, intestinal number of worms and fecundity, and also gastric emptying time, cecum arrival time, small intestinal transit time and stool weight were determined. Assessments occurred at 0 (control), 3, 6, 9, 12, 15, 18 and 21 days post infection (dpi) with three infective loads (400, 2000, and 10,000 L). Gastric emptying was faster (p=0.0001) and the intestinal transit was significantly slower (p=0.001) during the infection time course. Also, linear mixed-effects models showed significantly changes in small intestinal transit after three parasite load over time. Cecum arrival was not influenced by infection time course or parasite load. As indirect effect, stool weight decreased accompanied a strong oviposition peak at 9 dpi in 400 L and 2000 L. In several motor function instances, neuromuscular dysfunction persists after mucosal inflammation has decreased. Our approach could be very helpful to evaluate gastrointestinal motor abnormalities in vivo after parasite infection. Despite parasitological data progressively decreased after 15 dpi, small intestinal transit worse over time and according to burden.