Study area
Havana is located in the 22°58’, 23°10’ north latitude and 82°30’, 82°06 west longitudes, and belongs to the western region of Cuba. The hydrography is composed by the Almendares, Martín Pérez, Quibú, Cojímar and Bacuranao rivers, among others aquifer reservoirs. The climate of the city is tropical, as in the rest of the island, and there are two seasons: rainy season between May and October and dry season between November and April, although it is possible that rains occur during the dry season due to the presence of cold fronts coming from the north. Havana province is administratively divided into 15 municipalities which are: Plaza de la Revolución , Habana Vieja, Centro Habana, Diez de Octubre, Cerro, Arroyo Naranjo, Boyeros, Playa, Marianao, La Lisa, Guanabacoa, Regla, Habana del Este, San Miguel del Padrón and Cotorro (Fig. 1). The city has a population of 2.1 million inhabitants (National Statistics Office of Cuba, 2011; Official Census, 2012).
Municipalities Classification
According the urbanization characteristics and the geographical location in the province, the municipalities were categorized in three groups: the peri-urban group, which are the peripheral or peri-urban municipalities Guanabacoa, Arroyo Naranjo, Boyeros and Cotorro characterized by having borders with other provinces and a concentrated urbanization in one specific area of the municipality: a mixed group, which are the municipalities Playa, La Lisa and Habana del Este which have borders with other provinces but with a scattered urbanization throughout the municipality; and an urban group , which are the municipalities of San Miguel del Padrón, Regla, Plaza de la Revolución, Marianao, Habana Vieja, 10 de Octubre, Centro Habana and Cerro which have a high population concentration in their territory and are concentrated in the center and north (sea-side) of the province surrounded by the municipalities of the other two groups. From now on, we refer to these three groups as ‘urbanization groups’.
Entomological sampling
The routine Aedes control program in Havana province inspects all houses and all vacant lots twice a month and every month, in 1995-1999 and 2010-2018 respectively. During these surveys, all water containing deposits are inspected for the presence of immature stages of the Aedes mosquito. Of every container positive for Aedes larvae, stages are collected and transported to the laboratory for species identification (dissociating Culex, Ae. albopictus, Ae. aegypti). For this study, we retrieved the data from all houses and vacant lots that were surveyed in all municipalities of Havana province during two periods: the first period corresponded to 1995 – 1999 and the second to 2010-2018. The personnel who carried out the sampling were from the Ae. aegypti and Ae. albopictus control program established in Cuba. House-level sampling methodology used was as recommended by the program [18-19] and consisted in starting at the opening point of the house-block and continuing so that each house on your right is visited; upon arriving at the house, once the permit for sampling has been granted, starting by the yard to continue later with the rooms, always right-side and from the entry forward, in case one cannot inspect a room, as well as some closed housing, this is duly noted and inspection is done on another day. The data is collected in the established form for the program.All types of deposits were reviewed (water storage recipients such as low tanks, buckets, elevated tanks, cisterns among others; small miscellaneous artificial deposits such as cans, knobs, bottles, animal drinkers, plastic cups; used car tires; drains and sewage pits, water registers; natural breeding such as trees hole, puddles, coconut shells). In Cuba, larvitraps [20] are used for surveillance of Ae. aegypti and Ae. albopictus in all municipalities, except during periods of intensive chemical treatment carried out in reaction to increasing Ae. aegypti infestation.
Mosquito samples identification
A sample was taken from each container being positive for mosquito larvae. This larvae sample is placed in a vial with a label containing the necessary information about its location, and is subsequently identified, using morphological keys for culicids [21-22]. These samples are first identified in the laboratories at the municipal level and subsequently sent to the provincial laboratory for quality control of the morphological identification of mosquito species. Specimens collected and identified remain in this laboratory. Ae. albopictus presence outside and inside the house was only recorded in the period 2013 – 2018. The location of the containers with Ae. albopictus were known to be outside the houses and hence this information was not reported in the first period 1995-1999. During 2010-2013 no data are available on Ae. albopictus.
Statistical analysis
The number of breeding sites where
Ae. albopictus was detected was mapped over the entire province and over the two study periods. Of all
Ae. albopictus breeding sites per study period, the relative importance per urbanization group was calculated. A descriptive analysis over time was done of the
Ae. albopictus breeding sites on co-existence or not with other species, including the most important species with whom it is associated. To evaluate the determinants of the presence of
Ae. albopictus breeding sites, we constructed a generalized linear random effect regression model with a negative binomial link function. This model considered the nature of the data (repeated measurements in municipalities). We evaluated the effect of belonging to one of the two periods and belonging to a certain urbanization group on the yearly municipal number of
Ae. albopictus breeding sites. For the periods separately, we estimated also the association between number of
Ae. albopictus breeding sites and the year (as covariate) and urbanization group (as factor). IBM SPSS statistics version 25 was used.