Dengue-Prevention and Control | Medical Science Optional Notes for UPSC PDF Download

Dengue-Epidemiological Factors for its Spread

Over the last decade, there has been a gradual rise in the number of dengue cases in India. The increase in dengue is attributed to intricate interactions among the host, vector, and virus, which are in turn influenced by climatic factors.

The spread of dengue in India can be linked to

• Unplanned urbanization
• Alterations in environmental factors
• Interactions between hosts and pathogens
• Population immunological factors

Inadequate vector control measures have also created favorable conditions for dengue virus transmission and its mosquito vectors.

Across the globe, numerous studies have documented shifts in spatial patterns of dengue transmission. The causes of these changes are connected to various factors, spanning from the global expansion of travel and trade, which facilitates the spread of pathogens and vectors, to alterations in climate or shifts in human behavior. The inability of urban authorities to furnish civic amenities and the presence of inadequate public health infrastructure elevate the risk of vector breeding at heightened levels, creating a conducive environment for transmission.

The vector's expansion into rural areas is a relatively recent phenomenon, correlated with the implementation of rural water supply schemes, enhancements in transport systems, water scarcity, and shifts in lifestyle.

Climate Changes

• The extrinsic incubation period (EIP) denotes the viral incubation span from the moment a mosquito consumes a viremic blood meal to the point when the mosquito becomes infectious.
• Nevertheless, even a temperature rise of 2°C would result in a shortened extrinsic incubation period for DENV, leading to a greater number of infected mosquitoes being available for an extended duration.
• Additionally, mosquitoes are prone to bite more frequently due to dehydration, thereby increasing human-mosquito contact.

Vector

• Aedes aegypti is a highly domesticated, strongly anthropophilic, nervous feeder (i.e., it bites more than one host to complete one blood meal) and is a discordant species (i.e., it needs more than one feed for the completion of the gonotropic cycle). 
• This habit results in the generation of multiple cases and the clustering of dengue cases in the cities.

The Directorate of the National Vector Borne Disease Control Program serves as the central hub for the surveillance and prevention of dengue in India. The Integrated Disease Surveillance Program also plays a crucial role in monitoring and detecting outbreaks of dengue across the country.

Reporting of Dengue Cases:
The Ministry of Health and Family Welfare, Government of India, has mandated the compulsory notification of dengue cases. It is mandatory for all government health institutions, private hospitals, and clinics to inform the office of the district health authority in their respective districts about suspected dengue cases reported at their healthcare facilities on a weekly or daily basis during the transmission season.

Precautions

• Water from coolers and various small containers (such as plastic containers, buckets, used automobile tires, water coolers, pet watering containers, and flower vases) should be eliminated at least once a week.
• Suitable larvicides should be applied to water storage containers that cannot be emptied.
• Water storage containers should be consistently covered with lids.
• Aerosol can be employed during the daytime to ward off mosquito bites.
• During the transmission season (rainy season), individuals can wear clothing that covers their arms and legs.
• Mosquito nets or mosquito repellents can be utilized while sleeping during the daytime.
• Personal protective measures like window screens, insecticide-treated bednets, coils, and vaporizers can be employed to prevent mosquito bites.

It is essential to shield dengue patients from mosquito bites to prevent the further transmission of the disease to other individuals.

Environmental Management & Source Reduction Methods

• Identification and eradication of mosquito breeding sources
• Maintenance of rooftops, porticos, and sunshades
• Securing proper covering for stored water
• Ensuring a dependable water supply
• Observance of weekly dry days

Health Education

• Disseminating information to the general public about the disease and vector through various media channels such as television, radio, cinema slides, etc.

Community Participation

• Creating awareness and engaging the community in identifying Aedes breeding sites and actively participating in their elimination efforts.

GOI initiatives

The Government of India has implemented various measures for the prevention and control of Dengue and Chikungunya in the country, as outlined below:

• Formulated a Long Term Action Plan for the Prevention and Control of Dengue nationwide, which was distributed to the States in January 2007 for execution.
• Issued national guidelines in April 2007 for the clinical management of Dengue Fever, Dengue Hemorrhagic Fever, and Dengue Shock Syndrome, intended for circulation in all hospitals across the States.
• Established Sentinel Surveillance Hospitals with laboratory support to enhance diagnostic capabilities for Dengue in endemic States in 2007, a number that has expanded to 170 in 2009. These hospitals are linked with 13 Apex Referral Laboratories equipped with advanced diagnostic facilities for additional support.
• To ensure consistency and standardization in diagnostics across these laboratories, IgM MAC ELISA test kits are supplied through the National Institute of Virology (NIV), Pune, with the associated costs covered by the Government of India.
• The diagnosis of Dengue and Chikungunya is provided to the community free of charge.
• Since 2007, the Directorate of NVBDCP prepares an annual tentative allocation of test kits in the 1st quarter, based on the previous epidemiological situation of Dengue and Chikungunya in the states. This allocation is communicated to both NIV, Pune, and the States, and the kits are supplied by NIV, Pune, upon receipt of requirements from the respective states.

The responsibility for ensuring the diagnostic facility and the availability of kits lies with the respective State Programme Officers of NVBDCP.

National Dengue Day

In India, National Dengue Day is observed on May 16, as recommended by the Ministry of Health and Family Welfare, Government of India. This initiative aims to raise awareness about dengue and enhance preventive measures and preparedness for disease control in the country before the onset of the transmission season.

Global strategy for dengue prevention and control (2012-2020)

Dengue poses a worldwide menace, necessitating a collective response from all potential collaborators. The global strategy advocates for coordination and collaboration among multisectoral partners, emphasizing an integrated vector management approach and sustained control measures across all levels.

The objectives are:
a. To decrease dengue mortality by a minimum of 50 percent by 2020
b. To decrease dengue morbidity by a minimum of 25 percent by 2020
c. To assess the true burden of the disease by 2015.

Dengue-Repeats

Discuss in brief the epidemiological factors which have led to the spread of dengue in different parts of the country. Discuss in brief the guidelines laid down by the Directorate of National Vector Borne Diseases Control Programme for the prevention and control of dengue. (2018)