Abstract
Aedes-borne diseases remain a public health challenge for many countries globally. The extent of spread of invasive species of Aedes mosquitoes and risk of transmission of the diseases especially around the point of entry of goods such as ports is not well known in Ghana. This study investigated the ecology, distribution and risk of transmission of viral haemorrhagic fevers by Aedes mosquitoes around the port areas of Tema, Southern Ghana. The mosquitoes from this study were collected using human landing catches, ovitraps and larval collections for a period of six months. A total of 1092 containers were inspected in both seasons and of these, 237 (21.7%) were positive for mosquito larvae or pupae in rainy season while 181 (16.6%) were positive in dry season. A total of 6498 mosquitoes were collected and identified morphologically using taxonomic keys. 6038 (92.9%) were Aedes aegypti, 337 (5.2%) were Culex spp. and 123 (1.9%) were Anopheles gambiae. The Ae. aegypti larvae were found breeding in a series of water-holding containers which included disposed plastic containers, earthenware pots, car tyres, plastic barrels, plastic basins, buckets, metal drums, jerrycans and poly tank. A high proportion of Aedes aegypti eggs were found in the ovitraps during the rainy season than in the dry season in the study sites. Ae. aegypti was the most common mosquitoes biting mostly outdoors (65.6%) with more bites occurring in the rainy season (63.6%) in the two residential sites (Tema Community One and Tema New Town). The risk of transmission of viral haemorrhagic fever in the study sites was assessed using House Index, Container Index, Breteau Index and was found to be higher in Tema New town area with seasonal variations within the sites. The man-vector contact rates for the two residential sites were also found to be higher in rainy season than the dry season. These observations indicate that the risk of transmission of viral haemorrhagic fevers in the study areas is high especially in the rainy season. The implications of the findings in the formulation of future vector control programmes around the port areas in the country are discussed in the paper.
Highlights
Aedes mosquitoes (Diptera: Culicidae) are known to occur in the tropics and subtropics currently, they have been established in all parts of the world with the exception of Antarctica [1] [2] allowing the entry and epidemics of viruses into new populations of susceptible human hosts
This study investigated the ecology, distribution and risk of transmission of viral haemorrhagic fevers by Aedes mosquitoes around the port areas of Tema, Southern Ghana
The ovitrap index ranged from 2.5 to 12.5 with the highest index recorded at the Golden Jubilee Terminal (Figure 2)
Summary
Aedes mosquitoes (Diptera: Culicidae) are known to occur in the tropics and subtropics currently, they have been established in all parts of the world with the exception of Antarctica [1] [2] allowing the entry and epidemics of viruses into new populations of susceptible human hosts Various species in this genus are found in different parts of the world with distribution into new geographical limits made possible by international trade and various human activities. Aedes mosquitoes have been reported to breed in various sites which include discarded cans, earthenware pots, tree holes, rock pools, crab burrows, car tyres, etc Some species in this genus transmit arthropod-borne viruses of public health importance including dengue fever, yellow fever, rift valley fever, Venezuelan equine encephalitis, Japanese encephalitis, zika, la Crosse viruses and chikungunya [5] [6] which negatively impact the economy of many countries. It is known that the spread of the container-breeding species Ae. albopictus and Ae. aegypti beyond their native range has been facilitated by the trade of goods, significantly in used tyres and machinery through the land and sea ports [8] [9] [10]
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