Characterization of giraffe ear disease in Mikumi Selous Ecosystem
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Date
2010
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Publisher
Sokoine University of Agriculture
Abstract
A study on GED was conducted in the Mikumi - Selous ecosystem with an overall
objective of finding the cause and predisposing factors. Giraffes were examined for
change in conformation, discharges, and lesions on the pinna. Samples were
collected from immobilized giraffes. Water and browsing materials in giraffe habitat
were collected for micro-organisms isolation. Tick and oxpecker surveys were
conducted. GED overall magnitude was 11.7% (dry) and 11.1% (wet) seasons (1999
to 2006).3.1% (dry) and 8.1% (wet) seasons (2007 to March 2010). Matambwe in
Selous Game Reserve 1.2% (dry) 2.4% (wet), MINAPA 0.8% (dry) and 1.2% (wet)
seasons (2007 to March 2010). The difference mean sick giraffe examined in each
ecozone seasonally was not statistically significant (P > 0.05). Immobilized giraffes
revealed thickening of the ridges of antihelix, and distal part of the scapha,
superficial erosion, pus, and foul smelling of the pinna concave surface. GED
harboured environmental bacteria Pseudomonas auregenosa and Bacillus firmus.
Rhipicephalus appendiculatus and Amblyoma variegutum were common ticks
associated with giraffes. Ticks and oxpeckers played no role on GED occurrence.
Histologically GED biopsies had epidermal nematode larvae and interepidennal
necrosis. Molecular investigation concluded the nematode was a Spirurid. GED is
dermatitis caused by Spirurid nematode. The DNA sequence lies between
Onchocerca and Dirofilaria species which are parasitic to human and animals. It is
therefore a species that is new and specific to this ecosystem. Furthermore, possibly
it is a species that have evolved from older, non pathogenic and common
environmental agent. It is concluded that for the first time this work has been able to demonstrate and isolate a Spirurid nematode which is the primary cause for GED
with bacteria and fungi working together. The mechanism by which the nematodes
and bacteria cause the damage to the pinna is of interest. Also the trend of the disease
magnitude was downwards. It is recommended GED be known as Giraffe Pinna
Dermatitis. Mechanisms by which the nematodes cause lesions and role of vectors
need further study. Establishment of national nematode bank, reference archive with
identification keys, micro weather stations, electronic geomaps, and monitoring
programme.
Description
THESIS SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.
Keywords
Giraffe ear disease, Micro-organisms isolation, Mikumi Selous Ecosystem, Giraffe habitat, Rhipicephalus appendiculatus, Amblyoma variegutum