Seasonal Dynamics of Tsetse and Trypanosomosis In Selected Sites of Southern Nation, Nationalities and Peoples Regional State (SNNPRS), Ethiopia
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Date
2004-06
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AAU
Abstract
A seasonal dynamics of tsetse and tryp3nosomosis study was carried out in selected sitcs of
Southern Nation, Nationalities and Peoples Regional State (SNNPRS). The purposes of the
study were to determine the seasonal apparent density of tsetse and prc\'atcnce of
trypanosomosis, to identify tselse and trypanosome species and to assess Ihe
curative/prophylactic effect of isomctamidium chloride in selected ltilclt (BaJ ayc and Gadala
PAs) of SNNPRS. Community members (n ;; 80) were inten'icwcd using prepared
questionnaire format. Cross sectional studies were carried out from Oelober to April during
late wei (October), early dry (December), latc dry (February) and carly wet (April) seasons in
villages of 8adayc and GadaJa PAs. Samples for parasitological and entomological studies
were collected from one village of Badaye and two villages of Gadala PAs per season.
Bi conical traps used for entomological survey were deployed at grazing and watcring points
of anima ls in the villages of Badaye and Gadala PAs. For parasitological study, a total of
1,509 blood samplcs were collected from randomly se lected canle within four seasons. For
longitudinal fie ld study, parasitaemic Zebu callie (n = 64) were selected fo r isometamidium
chloride block treatment Parasilaemic callie wi th 39 (60.9%) T. congo/elise, 24 (37.5%) T.
vivax and I (1.6%) mixed (T. congo/elise and T. "imx) infections were treated wilh
prophylactic dose of (I mg/kg bw) isometamidium chloride at day 0 and monitored at day [5,
30, 60 and 90. The result of questionnaire revealed that 97.5% of respondents depend on
smugglers for trypanoc idal drugs and sick an imals were treated by smugglers and owners
with hi gh treatment frequency (6 limes per cattle per year). The entomological fi nding
revealed three tsetse species namely, G. m. sllbmorsilalls, G. / llscipes and G. paflidipes at
Badaye and Gadala PAs, respectively. Higher catches of G. pa/lidipes were registered during
late wei (October) and early dry (December) seasons in comparison with laIC dry (February)
and early wet (April) seasons. There was a signi fi cant difference (p < 0.05) in mean calches of
G. pallidipes belween seasons. The apparent density of G. palfidipes was positively correlated
(r :::: 0.5176) with prevalence of trypanosome infection.The ovcr.J11 trypanosome infection
prevalence in caule was \5.77%. During late wet and early dry seasons, the prevalence of
trypanosomosis was high (2 1.5%) and during laIc dry and early wet seasons low (10.8%).
During early wet season, significantly (p < 0.05) higher prevalence was registered at village
of Badaye PA (1 5.38%) than the vi llages of Gada la PA (8.51 %). There was a significan t
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difference (p < 0.00 1) in trypanosome infection preva lence between seasons. Giemsa stained
blood smear examination revealed Ihe presence of T. congo/ense lind T. viva.r in the study
area. T. congo/elise was dominant species and accounted for 63.4% in overall infections. TIle
overall mean rev value was 24.02%. The mean rev values of different seasons were
negatively correlated (r = ยท0.3112) with the prevalence of trypanosomosis of corresponding
seasons. There was a statistically signilicant difference (p < O. OOOl) between mean pev
values of parasitacmic and aparasitaemic callIe tested duri ng differen t seasons. There was a
significant difference (p < O.OOI) in trypanosome infections between different age groups of
cattle. In longitudi nal field study, parasitaemia was demonstrated in 17 out of 64 cattle
(26.56%) with in 15 days, 19 out of 64 cattie (29.7%) with in 30 days, 4\ out of 64 callie
(64.06%) with in 60 days and 44 out of 64 (68.75%) with in 90 days post treatment of Imglkg
bw isometamidium chloride. T. congo/elise was accounted for 85.5%. 89.5%. 78% and 79.5%
of infections within 15. 30, 60 and 90 days post treatment of isometamidium chloride.
respectively. Based on these results it is concluded that trypanosomosis is the major constraint
of livestock production in the study siles.
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Keywords
Season. Tsetse fly, Trypanosomosis, Trypanosomes, Prevalence. Drug resistance. Isometamidium chloride, PA