Dengue activity has been reported sporadically in Angola. Aedes aegypti is mainly the Dengue vector in this country. The objective was to obtain information about the spatial distribution and the mainly breeding sites of Ae. aegypti, as well as, to determine the indexes (house, containers and Breteau) in Luanda. The study was carried out from April 2014 to March, 2015. Ae. aegypti was present in all municipalities of Luanda province. A total of 8 190 households were surveyed, of which 1 171 were positive to Ae. aegypti larvae. Values of the Aedes indexes showed variation during the study period. Water storage containers represented 88,6% of the total containers positive to Ae. aegypti. This work represent the first sampling was performed to determine the presence and identification of breeding sites of Ae. aegypti in whole Luanda province during this century, aspect of great importance for the establishment of a control program vector of Dengue in Angola.

del Carmen Marquetti Fernández M, Flores YH, Nuviola DL (2017) Spatial Distribution and Mainly Breeding Sites of Aedesaegypti (Diptera:Culicidae) in Luanda, Angola. Ann Community Med Pract 3(1): 1017.

•    Aedes aegypti
•    Spatial distribution
•    Breeding sites
•    Luanda
•    Angola

Aedes aegypti mosquito is originated in Africa and spread to other tropical countries in the 17th and 18th centuries [1- 5]. Other Aedes species mosquitoes, including Aedes simpsoni, Aedes africanus, and Aedes luteocephalus, are reported in Africa and Angola. These species are potential Dengue vectors. Ae .aegypti was recorded by first time in Angola in 1903 [6]. Survey conducted by the National Malaria Control Program during 2010–2012 showed that Ae. aegypti was the only Dengue vector registered in Angola at that moment in Angola [5].

Dengue epidemics have been reported in Africa since the 19th century, in countries including Zanzibar (1823, 1870), Burkina Faso (1925), Egypt (1887,1927), South Africa (1926– 1927), and Senegal (1927–1928) [2,7]. Between 1960 and 2010, 20 laboratory-confirmed outbreaks were reported in 15 African countries, with most occurring in Eastern Africa. All four Dengue virus serotypes have been isolated in Africa, with serotype 2 reported to cause the most epidemics [8]. Available data suggest that Dengue is endemic to 34countries across all regions of Africa of these, 22 have reported local transmission, which is laboratory-confirmed in 20 countries, while two (Egypt and Zanzibar) do not have laboratory confirmation. The remaining 12 countries have only diagnosed Dengue in travelers who had returned to non-endemic regions [4].

In Angola, Dengue activity has been reported sporadically. On April, 2013, the Public Health Directorate of Angola announced that six cases of dengue had been reported to the Ministry of Health of Angola (MHA). As of May 31, a total of 517 suspected Dengue cases had been reported and tested for Dengue with a rapid diagnostic test (RDT). All suspected cases were reported from Luanda Province, except for two from Malanje Province. Only Dengue sero type 1 was detected by molecular diagnostic testing [5].

There is only scanty data available about Ae. aegypti during this century in Angola for this reason the objective of this study was to obtain information about the spatial distribution and the mainly breeding sites of Ae. aegypti, as well as, to determine the indexes (House, Containers and Breteau) in Luanda, in order to collect baseline information that could be useful for decision making during control operations aiming at preventing the possible epidemic occurrence in the country.

The study was carried out in Luanda, the capital city of Angola, as a population estimated of 6 542 944 in habitants (National Census data conducted from 15-31of May, 2014; National Institute of Statistics). A large proportion of the residents of Luanda live in densely populated urban slums. The city is divided in 7 municipalities Belas, Cacuaco, Cazenga, Icolo de Bengo, Quissama, Viana and Luanda municipality which has the same name as the province and is integrated by Ingombota, Maianga, Rangel, Samba, Sambizanga and Kilamba Kiaxi districts respectively. Each municipality is divided into comunes and these in neighborhoods. The rainy season is between November-May but the most accumulation of rain in Luanda occurs in March- April. Luanda had an annual rainfall of 323 millimeters during 2013 (Average Climatic Conditions Luanda, Angola; BBC Weather, 2013).

The data collection was conducted from April 2014 to March 2015. Sampling was carried out on all deposits containing water in the houses and in the vacant lots present in urban and peri-urban areas of the universo of each municipality in the province. Inspected deposit corresponded to: the water storage containers as basins, buckets, tanks, cistern, etc.; miscellaneous small artificial containers such as cans, jars, bottles, plastic cups etc.; used car tires; plants in water and potted etc. Household surveys of container-breeding mosquitoes were conducted randomly trying to cover the largest area of each municipality in the province. Four sampling (weekly) during the each month were carried out. From each positive container mosquito only larval sample was collected using a dropper, which was placed in vials containing 70 percent alcohol. The vials were labeled with the required information such as date and place of collection. The identification of the samples was using morphological keys [9,10]. A total of household in each sample was 35. The staff (5 persons) that performed the sampling belongs to the malaria program established in the province and trained for the activity by Cuban specialist in vector control. The indexes house, containers and Breteau were determined monthly. (House Index (HI): percentage of house with larvae; Container Index (CI): percentage of water-holding containers with larvae and Breteau Index (BI): the number of positive containers per 100 houses).

Ae.aegypti was present in all municipalities of the province with a major infestation Ingombota and Samba districts belonging to Luanda municipality; and Cacuaco and Cazenga municipalities in the studied period (Figure 1). Of a total of 572 neighborhoods registered for Luanda (Data from the Provincial Directorate of Health and Vector Control Program); 242(42, 3%) distributed in the study area were sampled, being found positive for Ae.aegypti larvae 237(97.9%). A total of 8 190 households were surveyed, of which 1171 were positive with Ae. aegypti mosquito larvae. During the study period House index oscillated between 4,3 in January to 27,9 in June, container index between 2,1 in January to 9,3 in May and Breteau index between 5,8 in January to 42,2 in June (Figure 2). The average household container with wáter was 5. A total of 1667 container were positive with Ae. aegypti larvae of which 1478(88.6%) were water storage containers (tanks >100 liters, tanks <100 liters, buckets, water wells, cisterns and basins) followed by plants in water and potted (7,3%); artificial miscellaneous containers (cups, jars, pots, toilet hole, bottles, etc) (2,5%) and used tires car (1,6%). Ae.aegypti larvae presence in artificial miscellaneous containers miscellaneous were founded mainly in May and June where it still accumulations of rain water are present (Figure 2).

During an outbreak of Yellow Fever in Luanda was founded that water-storage containers (mainly the bigger ones) accounted for 85 percent of the Ae. aegypti larval breeding, [11] the remaining were ornamental vases, abandoned objects, mainly with rainwater, of these, car tires were the most important type. During the survey carried out in 2013; 63, 1% belonged to water storage containers too [5]. In one study carried out in Senegal Ae. aegypti was founded in the storage containers (100% of the collected fauna), tires (96%), bamboo holes (90.6%) and discarded containers (51.4%) [12]. Similar result about the water storage container basically tanks was founded in Kenya during Ae. Aegypti pupa/demographic- survey [13]. On the other hand [11] founded that Aedes indexes varied greatly reaching Breteau index values of about 40 during the rainy season in Luanda. Ours results coinciding with these previous findings. Urbanization is a major factor in facilitating the increase of Aedes sp. Mosquito populations [14], together with the accumulation of non-biodegradable, human-made containers in and around living areas, as well as deficiencies in the supply and distribution of water has provided the aquatic environment required by these mosquitoes in this country and in the continent [13].

It has long known of the existence of Dengue in Africa, but its epidemiology and the vectors studies are poorly documented. Dengue prediction models suggest that the true burden of Dengue in Africa can approach that of South America [8]. In Angola, Dengue activity has been reported sporadically. Early surveys in the 1960s revealed no evidence of Dengue activity [14], while outbreaks of clinically suspected dengue in the 1970s were proven to be caused by Chikungunya [15]. In the 1980s an outbreak of Dengue was reported from Luanda, with subsequent reports of travel-related Dengue acquired in Angola, by travellers from the Netherlands [16] and Brazil [17]. For a Brazilian travel-related case, the serotype identified was Dengue - 2. Since then, there has been little information on the risk of Dengue in Angola [19]. This may represent an absence of disease activity, or a lack of awareness, diagnostic resources and active surveillance. The origin of Dengue -1 strain responsible for the Luanda outbreak in 2013 is yet undetermined, while that the cases of Dengue and Chikungunya occurred during 2014, were confirmed by rapid test in Luanda but the circulating Dengue serotype was not identified.

In conclusion this work represent the first sampling was performed to determine the presence and identification of breeding sites of Ae.aegypti through out the whole Luanda province, aspect of great importance for the establishment of a control program vector of Dengue and Chikungunya. It is important to know besides that the values registered for Breteau and House indexes allow the occurrence of dengue epidemicso it entomological indicators should stimulate strength then the diagnostic in health institutions in Luanda for to know the real situation of this disease in Angola.

The authors wish thanks to Ministry of Health in Angola, Provincial Health Director of Luanda; all Heads of Health at the municipalities and districts levels; Angolan brigades vector control staff; Cuban specialists belonging to Control Programm Anti-Larval Against Malaria (LABIOFAM) and the Population of the province of Luanda for his contribution to the realization of this work.

1. Cornet M. Dengue in Africa. Epidemiology of dengue and dengue hemorrhagic fever. Monograph on dengue/dengue hemorrhagic fever. Geneva. World Health Organization. 1993; 39-47.

2. Gubler DJ, Clark GG. Dengue/dengue hemorrhagic fever: the emergence of a global health problem. Emerg Infect Dis. 1995; 1: 55- 57.

3. Halstead SB. Dengue: overview and history. In: Halstead SB, editor. Dengue. London: Imperial College Press. 2008; 1-28.

4. Were F. The dengue situation in Africa. Paediatr Int Child Health. 2012; 32: 18-21.

5. Ongoing Dengue Epidemic-Angola June 2013. MMWR Morb Mortal Wkly Rep. 2013; 62: 504-507.

6. Roque AB. Contribuição para o estudo da malaria e dos mosquitos de Angola. A Med Contemp Lisboa. 1903; 6: 110-115.

7. World Health Organization Dengue: guidelines for diagnosis, treatment, prevention and control. Geneva. World Health Organization. 2009.

8. Amarasinghe A, Kuritsky JN, William Letson G, Margolis HS. Dengue virus infection in Africa. Emerg Infect Dis. 2011; 17: 1349-1354.

9. Ribeiro H, Da Cunha R. Research on the mosquitoes of Angola. VIII-The genus Aedes Meigen, 1818 (Diptera: Culicidae). Check-list with new records keys to females and larvae, distribution taxonomic and bioecological notes. Separata dos Anais do Instituo de Hygiene e Medicina Tropical. 1973; 1: 1-44.

10. González R. Culícidos de Cuba. Editorial Científico Técnica. 2006.

11. Ribeiro H. Entomological studies during the 1971 yellow fever epidemic of Luanda, Angola. Mosquito News. 1971; 4: 568-574.

12. Diallo D, Diagne CT, Hanley KA, Sall AA, Buenemann M, Ba Y, et al. Larval ecology of mosquitoes in sylvatic arbovirus foci in south eastern Senegal. Parasit Vectors. 2012; 5: 286-292.

13. Kokernot RH, Casaca VM, Weinbren MP, Mcintosh BM. Survey for antibodies against arthropod-borne viruses in the sera of indigenous residents of Angola. Trans R Soc Trop Med Hyg. 1965; 59: 563-570.

14. Midega JT, Nzovu J, Kahindi R, Mbogo C. Application of the pupa/ demographic-survey methodology to identify the key container habitats od Aedesaegypti (L) in Malindi district, Kenya. Ann of Trop Med & Parasitol Suppl. 2006; 1: 61-72.

15. Monath TP. Dengue: the risk to developed and developing countries. Proc Natl Acad Sci. 1994; 9: 2395-2400.

16. Filipe AF, Pinto MR. Arbovirus studies in Luanda, Angola. Virological and serological studies during an outbreak of dengue like disease caused by the Chikungunya virus. Bull World Health Organ. 1973; 49: 37-40.

17. Bakker RC, Veenstra J, Dingermans-Dumas AM, Wetsteyn JC, Kager PA. Imported Dengue in the Netherlands. J Travel Med. 1996; 3: 204-208.

18. Vasconcelos PF, Travassos da Rosa ES, Travassos da Rosa JF, De Freitas RB, Dégallier N, Rodrigues SG, et al. [Outbreak of classical fever of dengue caused by serotype 2 in Araguaiana, Tocantins, Brasil]. Rev Inst Med Trop São Paulo. 1993; 35: 141-148.

19. Schawartz E, Meltzer E, Mendelson M, Tooke A, Steiner F, Gautret P, et al. Detection on four continents of dengue fever cases related to an ongoing outbreak in Luanda, Angola, March to May 2013. Euro Surveill. 2013; 18.