Vibrio cholerae reservoir, indicators of pollution: community structure of chironomidae (Dipteria) in Olezoa stream, Yaoundé (Cameroun).

CaHReF 20116, Yaoundé Conges hall, 23 – 26 August 2016 , PL044

The natural reservoir of Vibrio cholerae has long been assumed to be humans, but it appears that there is no chronic state of the disease. Evidence to date suggests that the natural reservoir is in the aquatic environment. Findings by Halpern et al. (2003) support the hypothesis that the association found between chironomids and the cholera bacteria is not a rare coincidence, indicating that chironomid egg masses serve as yet another potential reservoir for V. cholerae.

It is for this reason that the first part of our study was carried out at the Olezoa stream in Yaounde from November 2013 to May 2014 to identify the chironomid genera that are present in the stream, determine the physicochemical properties of the water, and describe the relationships between species composition of chironomid communities and environmental parameters and the second part of the work will be on the relationship of the various chironomids species and V. cholera. This is to help fight endemic diseases specific to our tropical environment. The result show that Olezoa stream is slightly acidic (6.8 ± 0.2 CU), moderately mineralized (312.8 ± 95.4 µS/cm), rich in organic matter and less oxygenized (1.8 ± 1.3 mg/L) and rich in suspended solids (247.4 ± 172.4mg/L). 

The biological analysis of the stream showed a high biodiversity of the Chironomidae developmental stages, with a total of 11304 Chironomid developmental stages collected from the stream of which; 4188 were eggs, 2903 larva instars and 4213 pupal exuviae. Of the 4213 pupal exuviae, 609 individuals were identified into the tribe of Chironomini that revealed 03 genera which are: Chironomus, Goeldichironomus and Nilothauma. The most represented genus is Goeldichironomus (52.87%) while the least represented genus is Nilothauma (20.85%). The high biodiversity of the Chironomidae community suggest their degree of tolerance and sensitivity to aquatic pollution. This is due to the fact that the chironomidae developmental stages exhibit a variety of adaptations in polluted areas which could be: morphological, physiological and behavioral, occurring simultaneously within each developmental form and the different genera.

The relationship between the dynamics of the different genera and the physicochemical variable were confirmed by the

Chironomid,Olezoa stream, pupal exuviae,Larva instars