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.