Yellow fever vectors’ surveillance in three satellite communities of Enugu Municipality, Nigeria

Abstract

Outbreaks of yellow fever have continued to occur in various parts of Nigeria. Between 1985 and 2000, sporadic outbreaks have plagued some parts of Oyo, Ekiti, Delta, Imo, Anambra, Cross River, Lagos and Benue States of Nigeria. In addition to favourable environmental factors encouraging the development and spread of the viraemia, there is preponderance of Aedes mosquito vector populations, animal reservoir hosts and high number of non-immune human populations, which do not easily render themselves to vector and environmental management strategies. Regular vector surveillance to detect warning signs posed by vector activities and regular immunization of non-immune human populations have remained a reliable method of abating yellow fever outbreaks. In consequence, yellow fever vectors surveillance has been undertaken in three satellite villages (Obe, Nkalagu and Uwani-Uboji) of Enugu Municipality. Four immunized volunteers were used to collect adult
vectors, while locally adapted CDC (Centre for Disease Control) ovitraps were used to collect their eggs. Also, house inspection to detect the breeding index of vector populations in and around the houses was undertaken. Results of house inspections in the three communities showed that out of sixty (60) houses visited, 385 containers were found with water, 221 (57.6%) water containers had Aedes larvae with Uwani-Uboji and Obe communities having 83.5% and 53.8% of their water containers with
Aedes larvae. For the ovitraps, Nkalagu had an average of 22 eggs per trap. There were high numbers of Aedes africanus adults in the human bait collections at Obe and Uwani-Uboji communities. Aedes albopictus was amongst other mosquito species collected.