Abstract:
Aedes-borne viral diseases mainly Dengue (DEN), Zika (ZIK) and Chikungunya (CHK) have
contributed to mortality and morbidity in the world especially in Africa. There have been major
outbreaks recorded in West Africa. Ghana has not recorded any outbreak of these diseases but
the country is at risk of future outbreaks due to its proximity to West African countries where
outbreaks have been recorded. This study assessed the risk of transmission of Dengue (DENV),
Chikungunya (CHKV) and Zika (ZIKV) viruses in Larabanga and Mole Game Reserve area in
Savannah Ghana. The immature and adult stages of Aedes mosquitoes were collected from
Larabanga and Mole Game Reserve area. There was a significant (P<0.001) number of
mosquitoes collected during the rainy season than the dry season. A total of 1,930 Aedes
mosquitoes were collected during the rainy season and morphologically identified. Of these,
1,915 (99.22%) were Aedes aegypti and 15 (0.22%) were Aedes vittatus. During the dry season,
27 Aedes aegypti mosquitoes were collected. A total of 415 Ae. aegypti mosquitoes were
molecularly identified to subspecies level of which Aedes (Ae) aegypti aegypti was the
predominant subspecies. Both Ae. aegypti aegypti and Ae aegypti formosus exist in sympatry in
the area. All Aedes pools (75) were negative for DENV, ZIKV and CHKV when examined by
RT- PCR. Three Larval indices namely House Index, (HI) percentage of houses positive for
Aedes larvae or pupae, Container Index, (CI) the percentage of containers positive for Aedes
larvae or pupae and Breteau Index, (BI) the number of positive containers (with larvae and/or
pupae per 100 inspected houses) were assessed as a measure for risk of transmission. The HI, CI
and BI for both sites were as follows; Mole game reserve (HI,42.1%, CI, 23.5% and BI, 100 for
rainy season and 0 for all indices for dry season) and Larabanga (39%, 15.5% and 61 for rainy
season and 2.3%, 1.3% and 2.3 for dry season). The spatial distribution of Aedes breeding sites in both areas indicated that Aedes larvae were breeding in areas with close proximity to humans.
Information about the species composition and the potential role of Aedes mosquitoes in future
outbreaks of the diseases that they transmit is needed to design efficient surveillance and vector
control tools.
