Prevalence of parasites in silvery mole rats in Morogoro region, Tanzania

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Date

2024-05

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Sokoine University of Agriculture

Abstract

The silvery mole rat (Heliophobius argenteocinereus) is a subterranean rodent with a wide distributional range throughout Sub- Saharan Africa. They are herbivores feeding on underground organs of a variety of plants. Despite being used as a source of protein by some local communities in Africa, the rats have been reported to host several parasites. However, the status of the parasites infesting/infecting silvery mole rats in Tanzania has not been well studied. Exploring the ectoparasites and endoparasites species diversity in silvery mole rats opens up a fascinating avenue for understanding the intricate relationships between these underground-dwelling mammals and their parasites. It is intriguing to consider the potential threat for transmission of parasitic zoonoses between humans, livestock, and silvery mole rats due to the notable interactions in the environment. Consequently, the key aim of this study is to acquire crucial information about the ectoparasites and endoparasites in silvery mole rats in the Morogoro region, Tanzania. A survey to establish the status of ectoparasites and endoparasites in silvery mole rats was conducted in Mlali (Mlali, Mkuyuni, Mongwe and Kipera villages) and Mji mkuu wards of Mvomero and Morogoro urban districts in Tanzania, from March to June 2023. Silvery mole rats were collected manually using hand hoes excavation from their burrows in agroecological areas. The captured rats were euthanized using Diethyl Ether, ectoparasites were collected from animal fur, blood samples were collected directly from the heart, and GIT contents were collected by flushing the GIT using physiological saline after opening of the abdominal cavity. During postmortem adult worms found inside the tract and around the pelvic, thoracic, and abdominal cavities were collected and preserved in 70% ethanol. The collected ectoparasites were fixed in a series of alcohols, cleared in xylene, and mounted on microscopic slides. A flotation method was adopted for processing gastrointestinal contents, and the recovered adult helminths were processed by using lactophenol mounting techniques for nematodes and aceto-carmine staining techniques for cestodes. For hemoparasites detection, the blood and impression smears from the kidney, liver, and lungs were prepared and stained with Giemsa stain for microscopic examination. Using taxonomic keys, ectoparasites, hemoparasites, and helminths were identified based on their morphological features. The prevalence of ectoparasites, hemoparasites, and gastrointestinal parasites was computed, and a chi-square test was applied to assess the relationship between parasites and animal body parameters, the association with a p ≤ 0.05 was considered significant. One hundred thirty-seven silvery mole rats were collected, adult females 65% (89/137) were the dominant among the collected rats. A total of 1503 ectoparasites were collected, identified, and revealed to two taxa of mite spp which were Androlaelaps spp 93.15% (1400/1503) and Echinolaelaps spp 6.19% (93/1503), and one taxon of tick the Haemaphysalis spp 0.6% (10/1503) with an overall prevalence of 71.5% (98/137), mite species were the most abundant (94.98%). Two species of blood parasites were detected with an overall prevalence of 29.2% (40/137) and identified as Anaplasma spp 25.5% (35/137) and Babesia spp 16.8% (23/137). Three species of gastrointestinal helminth were detected including taxa of cestode and nematode. A taxon of cestode was identified as Hymenolepis diminuta with an overall prevalence of 20.44% (28/137). A total of 385 adult H. diminuta and 1450 cestode EPG were collected from the gastrointestinal tract. Two species of nematodes; Physaloptera spp and Strongyloides spp were revealed with an overall prevalence of 39.42% (54/137), Physaloptera infection was the most prevalent at 37.22% (51/137) and the only adult nematode recovered among the two nematode species. A significant association was shown between blood parasites and adult silvery mole rats (p = 0.004), and between ticks and babesiosis, tick and anaplasmosis with p of 0.001 and 0.01, respectively. The cestode infection had a significant association with both host age and reproductive category (p< 0.05). Adult silvery mole rats had a lower infection risk than sub-adult rats, with an odds ratio of 0.6 (95% CI 0.24-1.87). Female silvery mole rats were at higher risk of being infected with nematode parasites compared to males, with an odds ratio of 1.6 (95% CI 0.78-3.43). The findings of this study indicate that ectoparasites, hemoparasites, and gastrointestinal helminths are prevalent among silvery mole rats in Morogoro region and might be the source of the infection in humans and livestock. Further studies on the epidemiology of the parasites identified and others that were not found in this study at the molecular level for advanced characterization are recommended to explore their zoonotic potential.

Description

MSc. Science in Public Health Pest Management

Keywords

Silvery mole rats, hemoparasites, ectoparasites, nematodes, cestodes, Prevalence, Morogoro.

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