Studies on ecology and epidemiological importance of glossina swynnertoni austen, near Aitong, Maasai Mara, South Western Kenya

Abstract

Different trap designs and colours were tested for G. swynnertoni. A turquoise blue colour variation of the Siamese trap was adopted as the standard for sampling. Further trap tests showed the turquoise blue Triangular trap to be better. G. swynnertoni occupied three core habitats near Aitong: namely, thicket, wooded grassland and Acacia community. Except in the Acacia community habitat, it occurred in association with G. pallidipes. The density of G. swynnertoni varied among habitats being highest in the Acacia community, intermediate in the wooded grassland and lowest in the thicket. In addition, density varied seasonally. Studies on activity patterns of G. swynnertoni using coloured electric screens showed a unimodal pattern for both males and females. The activity of males peaked between 1100-1200 h then dropped gradually. Flies remained relatively active throughout the afternoon but activity decreased rapidly towards sunset (1700- 1800 h). Activity of females was very low in early morning but rose gradually to peak between 1400-1500 h; females remained active until sunset. Analysis of bloodmeals by Enzyme-linked Immunosorbent Assay (ELISA) 1ndicated that G. swynnertoni fed mainly on Suidae (64.2%). Other less-favoured hosts included ruminants (4.5%), hippopotamus (3.0%), Felidae (1.5%) and man (3.0%). Out of 1,612 G. swynnertoni dissected, 11.0% were infected with trypanosomes. Of these, 8.7% had T. vivax-type infection, 1.7% Nannomonas-type infection and 0.4% immature gut infection. No salivary gland infection was encountered although hypertrophied glands (virus-infected) were observed frequently. However, batch-feeding of tsetse on rats prior to dissection or passage of gut procyclic forms after dissection into G. m. centralis revealed the presence of T. brucei-type infection. In total, 20.9% of the resident cattle were infected with trypanosomes. Characterisation of trypanosome isolates by Polymerase Chain Reaction (PCR) and hybridisation of the amplified products with specific DNA probes revealed the presence of Trypanozoon parasites and T. congolense savannah-type in both cattle and wild G. swynnertoni. Amplification of genomic DNA of T. congo/ense savannah-type isolates from around Aitong, Maasai Mara and other geographical areas in arbitrarily-primed PCR revealed intra-specific variation.