Short Note-4
Rising Trend of Aedes aegpyti Indices at Various International Ports and Airports of India by
KS Gill, SK Sharma, Rakesh Katyal and Kaushal Kumar National Institute of Communicable Diseases, 22, Shamnath Marg, Delhi – 110 054
All international ports and airports in India are under entomological surveillance for the prevention of yellow fever as per the requirements of the International Health Regulations (IHR). A recent outbreak of dengue haemorrhagic fever (DHF) in Delhi during 1996(1) recorded 10,252 cases with 423 deaths. These developments heightened the perception of the threat of yellow fever in all countries of the South-East Asia Region(2). Recognizing the need for a stricter implementation of IHR at international ports and airports, the WHO Regional Office for South-East Asia organized a special case study on the implementation status of IHR in three countries of the Region(3) and, later, held a Regional consultation on disease surveillance and control at ports and airports during October 1998(4). Major recommendations enjoined upon Member countries to strictly implement IHR to keep ports/airports free of Aedes aegypti infestation, not only as a preventive action against yellow fever but also to arrest the spread of DHF. As a sequel to these recommendations, the National Institute of Communicable
Diseases, which is the monitoring agency for the control of Aedes aegypti at ports/airports in India, carried out a retrospective study of the data for all major ports and airports during 2001. Table 1 below lists the larval indices of Aedes aegypti at various international ports/airports for the periods for which records were available(5).
Larval indices at international airports A retrospective analysis revealed that at Kolkata airport, the larval indices ranged from 0.0% in 1963 to 26.9% in 2000, whereas, at Chennai airport, these ranged from 0.0% in 1948 to 38.8% in 1999. In Mumbai, it ranged from 0.0% in 1956 to 9.2% in 1995. In Delhi it ranged from 0.0% in 1965 to as high as 60.7% in 2000, while in Vishakhapatnam it ranged from 2.2% in 1997 to 14.7% in 2000. Airports recently declared as international also recorded very high indices: Cochin (66.6%), Kozikhode (5.1%), Bangalore (7.9%), Thiruvananthapuram (5.2%) and Goa (15.3%).
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Rising Trend of Aedes aegpyti Indices at Various International Ports and Airports of India
Table 1. Larval indices of Aedes aegypti at various international ports and airports in India Name of the city Kolkata (Calcutta) Period 1948 1963 1965 1978 1997 2000 1948 1964 1965 1998 1999 1956 1961 1965 1977 1995 1965 1977 1997 2000 1948 1964 1997 1998 1999 2001 1948 1978 1999 1998 1999 1998 1999 1998 1999 1978 2000 Aedes aegypti larval index Airport Seaport 1.0% 1.0% 0.0% 0.0% 0.0% 0.0% 18.67% 3.61% 8.81% 26.9% 29.6% 0.0% 0.0% 0.0% 1.0% 13.5% 6.6% 38.8% 22.8% 0.0% 2.0% 0.46% 0.0% 0.0% 1.09% 12.2% 9.2% 12.19% 0.0% 0.0% 0.0% 60.7% 0.0% 2.5% 2.2% 13.3% 0.0% 9.6% 0.0% 16.1% 14.0% 29.45% 0.0% 1.5% 66.6% 5.8% 1.48% 5.1% 0.25% 7.9% 0.0% 5.2% 15.3% 29.3% 50.4%
Larval indices of Aedes aegypti in ports At Kolkata port, the larval indices increased to 29.6% during 2000 as against 0.0% in 1963; at Chennai, it increased to 22.8% in 1999 as against 0.0% in 1964. At Mumbai, it increased to 12.19% from 2% in 1956. At Vishakhapatnam, the indices increased from 0.0% in 1948 to 29.45% in 2001. At Cochin it increased to 5.8% in 1999 against 0.0% in 1948. In Goa, the indices increased to as high as 50.4% against 29.3% in 1978.
Chennai (Madras)
Mumbai (Bombay)
Increased incidence of larval indices at ports and airports It is apparent from the above table that major airports in India have shown substantial increases in the Aedes aegypti populations during the last three years. These ranged from 5% (in Kozikhode and Thiruvananthapuram) to 66% (in Cochin). A similar trend was observed at ports, but when compared to airports, the increase was almost 30-fold, with the exception of Goa, which recorded 50.4%. Constraints which hampered implementation of IHR included: • the
Delhi
Vishakapatnam
Cochin
Kozhikode (Calicut) Bangalore Thiruvananthapuram (Trivandrum) Goa - data not available
Lack of infrastructure for taking effective vector control measures and carrying out entomological surveillance; Expansion of ports/airports areas have led to the construction of new buildings, runways, hangers, workshops, tyre dumps, scrap yards, which have raised the breeding potential manifold; Multiple agencies without linkages with national disease control programme authority; 117
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Rising Trend of Aedes aegpyti Indices at Various International Ports and Airports of India
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Control strategies privately managed which do not conform to national/WHO guidelines; Increased use of consumable plastic containers with poor disposal arrangements; and Growth of slums within 400 metres of the peripheral areas of ports and airports.
References 1. Kaul SM, Sharma RS, Sharma SN, Panigrahi N, Phukan PK, and Shivlal. Preventing dengue and DHF. The role of entomological surveillance, J. Com. Dis., 1998, 30: 187-192. Kalra NL and Sharma VP. Yellow fever threat. Current Science, 1996, 71: 948. Kalra NL. Disease vector surveillance and control at ports/airports, Maldives, Sri Lanka and Thailand, 1998. SEA/VBC/63, WHO/SEARO, New Delhi. World Health Organization, Regional Office for South-East Asia, New Delhi. Report of a Regional consultation on disease vector surveillance and control at ports and airports, Bangkok, 26-29 October 1998, SEA/VBC/65. Anonymous. National Institute of Communicable Diseases, 22 Shamnath Marg, Delhi, India, Annual Reports for 1948, 1961, 1963, 1964, 1965, 1977, 1978, 1997, 1998, 1999, 2000.
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From the foregoing it is apparent that vector control activities at ports/airports in India require streamlining, with proper linkages among different stakeholders operating there and with the national disease control programme authority, who can provide technical inputs by way of capacity-building and guidelines.
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