Investigations on the parasite, vector and reservoir host of cutaneous leishmaniasis in Addis Ababa, Silti, Merabete and the Awash Region, Ethiopia
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Date
2006-07
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Addis Ababa University
Abstract
From January 2005 to May 2006, investigations on the parasite, vector and reservoir host
of cutaneous leishmaniasis in Addis Ababa, Silti, Merabete and Awash Region, were
carried out in different areas of Addis Ababa, Silti, Merabete and Awash-7, Addis Ababa
and Silti were discovered recently as Leishmania foci of cutaneous leishmaniasis in the
highlands of Ethiopia, Awash valleys were areas where sympatric Leishmania tropica
and L aethiopica were discovered for the first time from sandflies, Merabete is not very
well known for cutaneous leishmaniasis in humans, but visceral leishmaniasis' was
reported from children in the associated lowland. The current Leishmania epidemics in
South Eastern Addis Ababa along the gorges of Bulbulla and Akaki rivers was related to
settlement of people near the Bulbulla - Akaki river gorges where hyraxes and sandflies
(Phlebotomus longipes) co-existed in crevices and cracks of the basalt rocks. It was the
area where the zoonotic Leishmania cycle was maintained. In Silti, however, the
epidemics was related to the recent increase in number of hyraxes and sandflies as a
result of the ecological changes of the Kerate gorge that bisects the center of the town
(Kibet) and synanthropic adaptations of the hyraxes. The possible reservoir hosts that··
were examined for natural infection of Leishmania were 79 hyr'!xes, 12 Raltus raltus,.14·
Praomys spp., 41 bats, 3 mongooses and 3 genet cats. Samples from skin,: blood, liver;.
spleen and bone marrow were cultured in NNN medium in addition to .Giemsa stain,
Leishmania parasites were isolated in NNN medium only from three bush hyraxes
(Heterohyrax brucei) in Addis Ababa. The hyraxes from the other areas were negative for ..
Leishmania in NNN medium. The total infection rate of H brucei in Addis Ababa :was
6.3% (3/48) and the highest infection rate was from the Saris area, 11.1 % (2/18). The
hyrax infection rates in Kality were 5.9 %(1117). No infected hyraxes were found in
Kilinto (Akaki). The giemsa stains of the above· tissues were negative for amastigote
stage of Leishmania in the macrophages. Leishmania infection was not found in the guts
of sandflies dissected. Seasonality and age dependent infections in hyraxes were
observed. Infections in hyraxes were found only in April, June and September after
spring peak sandfly abundance and biting passed. In Addis Ababa, no adults (0/16) were
found infected, but infections occurred only in juveniles (2/25) and sub adults (1/10).
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Biology