Comparison between micro-hematocrit centrifugation technique and polymerase chain reaction (PCR) to detect Trypanosoma evansi in experimentally inoculated goats

Seasonal Variation and Factors Affecting Trypanosoma theileri Infection in Wild Sika Deer (Ezo Sika Deer Cervus nippon yesoensis) in Eastern Hokkaido

Trypanosoma (Megatrypanum) spp. are isolated from domestic and wild ruminants, including deer, worldwide. The prevalence of trypanosomes in mammals is influenced by a number of factors such as host age and vector abundance. However, the seasonal variation of and factors affecting trypanosome infection in the wild deer population remain elusive. In this study, we analyzed the seasonal variation in trypanosome prevalence and the factors that affect Trypanosoma theileri Laveran, 1902, infection in wild sika deer (Ezo sika deer) Cervus nippon yesoensis (Heude, 1884) in Eastern Hokkaido through a two-year survey. Seasonal variation in the prevalence of trypanosome infection in the deer population ranged from 0 to 41% as per hematocrit concentration and 17 to 89% as per PCR results. In general, the prevalence of T. theileri by PCR in 2020 was higher than that in 2019. Moreover, the prevalence was significantly higher in the aged population than among the younger population. These findings may explain why individual conditions and sampling season were associated with trypanosome prevalence. This is the first study to investigate the seasonal variation in and risk factors affecting trypanosome infection in wild deer.

Spatial-Temporal Variations in Parasitological Prevalence and Host-Related Risk Factors of Camel Trypanosomiasis and Its Vectors in North Eastern Kenya: A Repeated Cross-Sectional Study

Camel trypanosomiasis (Surra) is endemic in the Horn of Africa. Understanding the spatiotemporal variations in Surra prevalence, vector dynamics, and host-related risk factors is important in developing effective control strategies. A repeated cross-sectional study was conducted to determine the Surra parasitological prevalence, livestock reservoirs, vector density/diversity, and host-related risk factors in Kenya. Random samples of 847, 1079, and 824 camels were screened at the start of the dry season, peak dry season, and during the rainy season, respectively. Blood samples were examined using the dark ground/phase contrast buffy-coat technique, and Trypanosoma species were identified based on their movement and morphology in wet and stained thin smears. Reservoir status for Trypanosoma evansi was assessed in 406 cattle and 372 goats. A rainy and dry seasons entomological surveys were conducted to determine the Surra vector abundance/diversity and spatiotemporal density changes. Surra prevalence was 7.1%, 3.4%, and 4.1% at the start of the dry season, peak dry season, and rainy season, respectively. Camel co-infections by Trypanozoon (T. evansi or Trypanosoma brucei brucei) and Trypanosoma vivax were recorded. Spatial variations in Surra prevalence were recorded at the beginning of dry (X _{(7, N = 846)} ² = 110.9, p ≤ 0.001), peak dry (X _{(7, N = 1079)} ² = 42.2, p ≤ 0.001), and rainy (X _{(7, N = 824)} ² = 29.1, p ≤ 0.001) seasons. The screened cattle and goats tested negative for Trypanozoon (T. evansi or T. b. brucei), while two cattle tested positive for Trypanosoma congolense. Biting fly catches were composed of a single species from Tabanus, Atylotus, Philoliche, Chrysops, and Stomoxys genera. The total catches for Philoliche, Chrysops, and Stomoxys were higher in the rainy than dry season consistent with the prevalence results. Surra remains an important camel disease in the region with its prevalence varying in space and time. Camel co-infections by Trypanozoon (T. evansi or T. b. brucei) and T. vivax necessitate proper diagnosis of suspected cases and targeted therapy.

DOCUMENTATION OF TRYPANOSOMA EVANSI IN CAPTIVE TIGERS AND LIONS IN PUNJAB (2016-2018), PAKISTAN

Trypanosoma evansi is an important hemoparasite of a variety of animal species worldwide. This parasite is a threat to the health of domestic animals as well as wild animals, particularly those managed in captivity. The current study investigated the presence of T. evansi in captive tigers (Panthera tigris tigris) and lions (Panthera leo) in Pakistan. In total, 24 blood samples from 11 tigers and 3 lions (n = 14) were collected during the course of roughly 3 yr (2016-2018). Eighteen samples were subjected to both microscopic and molecular evaluation for the presence of T. evansi; the remaining 6 samples were processed for PCR only. Of the 18 samples tested by both methods, 3 (16%) and 8 (44%) were positive by microscopy and PCR, respectively. This highlights the higher sensitivity of PCR over microscopy for detection of trypanosomes. Of the 24 total samples evaluated by PCR, 12 (50%) were positive. The three sequences obtained showed 99% identity with variant surface glycoprotein genes of the different isolates of T. evansi. The sensitivity, specificity, positive predictive value, and negative predictive value of microscopy in identifying T. evansi was 37.5, 100, 100, and 66.7%, respectively, considering PCR as the gold standard. We recommend rigorous monitoring of captive tigers and lions for hemoparasites, particularly in winter and early spring in areas with high infection rate of this parasite, preferably via PCR.

Clinical and therapeutic aspects of an outbreak of canine trypanosomiasis

Trypanosomiasis caused by Trypanosoma evansi can seriously affect both domestic and wild animals. This article reports on an outbreak of canine trypanosomiasis on a farm in the Pantanal region of Brazil. The farm had 38 dogs, 20 of which died before receiving veterinary care. The remaining 18 dogs were underwent anamnesisn, clinical examination, hematological and biochemical evaluations. Blood smears and PCR analysis were performed for the diagnosis. The treatment protocols used according to the clinical recovery or parasitological cure of the dogs, using diminazene diaceturate, isometamidium chloride or quinapyramine sulfate. Post-treatment parasitological evaluation was performed by the microhematocrit technique. 7/18 dogs were PCR positive for T. evansi (confirmed by sequencing). There was clinical findings, which were consistent with both the acute and chronic stages of the disease in dogs. The infected dogs all exhibited at least one clinical sign of the disease. The hematological findings were compatible with trypanosomiasis, highlighting the hypochromic microcytic anemia as the main outcome. No treatment protocol was fully effective and the prolonged use of diminazene diaceturate caused the death of an animal. The trypanosomiasis can cause high rates of morbidity and mortality in dogs and difficulty in establishment an effective and safe therapeutic protocol.