Abstract
Toxoplasmosis is a cosmopolitan parasitic zoonosis, infecting human and other warm blooded animals worldwide and is caused by Toxoplasma gondii. This disease has economic importance in regard to animal reproduction, and it leads to abortions and neonatal complications in both animals and humans. The study was carried out from May 2014 to July 2017 with aims to determine epidemiology of toxoplasmosis in animals and humans in selected districts of Bangladesh and Nepal, and molecular detection of T. gondii parasite in aborted fetuses of ruminants in Bangladesh. To estimate the seroprevalence of toxoplasmosis and risk factors for toxoplasmosis in sheep, goats and cattle in Dhaka, Mymensingh, Sirajganj and Chittagong districts in Bangladesh, 1,104 sera samples (552 sheep, 300 goats and 252 cattle) were randomly selected and tested by an indirect enzyme linked immunosorbent assay (ELISA). A total of 495 blood samples from human and animals in Sunsari district of Nepal and 325 blood samples from human and animals in Dhaka and Mymensingh districts of Bangladesh were tested by lateral flow chromatographic immunoassay (LFCIA) (Toxo IgG/IgM Combo Rapid test®). Altogether 254 cat feces and 390 water samples were collected from Mymensingh and were examined under microscope to detect oocyst of T. gondii. Aborted fetuses of sheep, goat and cattle were collected from Mymensingh and were subjected to Polymerase Chain Reaction (PCR) assay using two different primers (TgB1 and TgTox4) to detect parasite. The risk factors were identified by multiple logistic regression analysis using R 3.2.2 (The R foundation for Statistical Computing, 2015). The overall seroprevalence was 12.2%, and was significantly (P=0.008) higher in goats (16.0%) than cattle (8.3%). The odds of seropositivity was 2.09 times (95% confidence interval [CI]: 1.23-3.67) higher in goats than cattle. The odds of seropositivity was 2.1 (95% CI: 1.00–4.84), 7.3 (95% CI: 2.71- 23.41) and 10.9 (95% CI: 5.42– 23.41) times higher in only sheep flocks, in Mymensingh district and in pregnant sheep than in mixed flocks, Chittagong district and non-pregnant sheep, respectively. The odds of seropositivity was 5.8 (95% CI: 1.13-24.62) and 4.3 (95% CI: 1.38-16.34) times higher in Holstein Friesian cross cattle and in Mymensingh district than in indigenous cattle and Chittagong district, respectively. Seroprevalence of toxoplasmosis was estimated to be 12.67% in human, 29.56% in goats, 12.00% in sheep, 8.70% in cattle and 36.36% in cats by using LFCIA in Sunsari district of Nepal. Toxoplasmosis was found to be significantly associated with abortion (58.33%, OR= 15.4, P=0.0001) in human in Nepal. Similarly, significantly higher prevalence of toxoplasmosis was found in pregnant goat (42.5%, OR: 2.46, p=0.0381) than non-pregnant in Nepal. Seroprevalence of toxoplasmosis was 10.7% in human, 6.0% in goats, 10.0% in sheep and 34.7% in cats by LFCIA in Dhaka and Mymensingh of Bangladesh. About 5.5% cat faeces and 3.08% water samples were positive for T. gondii oocysts in microscopic examination. Five sheep and three goats aborted fetuses were found to be T. gondii DNA positive by PCR assay. The PCR amplification of 529 bp fragment (PCR using TgTox4 primer) showed presence of gene in 6 tissues having 529 bp bands while B1 gene (PCR using TgB1 primer) was present in 3 tissues having 580 bp bands. Among tissue samples, brain, liver and heart of aborted fetuses showed presence of T. gondii. This study indicates that exposure of goats; sheep and cattle to oocysts of T. gondii are widespread, suggesting that the consumption of raw and undercooked meat of these animals might be a source of human toxoplasmosis. Risk factor information can be used to design control programs to reduce exposure. The results of the molecular diagnosis exhibited that T. gondii infection might be considered as a causative agent for abortion in ewes and does. Further studies are needed to investigate different genotypes of T. gondii that infect sheep, goat and cattle population.