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Disease outbreak news: Dengue fever – Pakistan, 14 December 2021

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Dengue is endemic in Pakistan, with the last notable outbreak, with 53,498 cases and 95 deaths, being reported between September to December 2019.

From 1 January to 25 November 2021, a total of 48,906 cases including 183 deaths (case fatality ratio (CFR): 0.4%) have been reported from four provinces including Punjab, Khyber Pakhtunkhwa, Sindh, Balochistan, and the federally administered Islamabad Capital Territory (ICT), and Azad Jammu and Kashmir autonomous territories (AJK), Pakistan.

As of 25 November, Punjab province reported the highest number of cases with 24,146 cases and 127 deaths (CFR: 0.5%) accounting for 49.4% and 69.4% of all cases and deaths, respectively. The deaths were mainly reported from Lahore district.

Khyber Pakhtunkhwa, a border province with Afghanistan, reported the second largest number of cases with 10,223 cases, accounting for 21% of all cases, and 10 deaths (CFR: 0.1%).

Sindh province reported 5,548 cases with 24 (CFR:0.4%) deaths followed by the federally administered ICT with 5,261 cases and 21 (CFR: 0.4%) deaths, Balochistan province with 2,054 cases, and AJK reported 1,674 cases with one (CFR:0.1%) death.

Public health response

The federal and provincial health departments are implementing public health measures, including the following:
Vector Surveillance and Control Activities:

  • As part of Integrated Vector Management (IVM), surveillance of Aedes larvae and space spraying activities are underway in Punjab province. Between 16 to 25 November, indices of Aedes larvae in all household (percentage of houses infested with larvae or pupae) and container indices (percentage of water-holding containers infested with larvae or pupae) have fallen below two which is less than the threshold of five. With the opening of a field hospital in Lahore, fumigation and spot checks have been carried out in Rawalpindi and Islamabad city.
  • In Islamabad, multi-sectoral coordinated activities including vector surveillance, larvae source management, destruction of mosquito breeding sites, active case and contact finding, clinical management of patients, waste management, space spraying, and indoor residual spraying have been launched to control the dengue outbreak.
  • In Khyber Pakhtunkhwa province, vector surveillance and control activities are ongoing in 10 Union Councils of Peshawar district, with a special campaign on vector surveillance and control activities launched from 4 to 13 November until 18November.
  • In Sindh, vector surveillance and control activities are carried out on an ad hoc basis.
  • In Balochistan, selective indoor residual spraying operations were conducted in Kech district in June and July. Breeding site management and space spraying activities are carried out on an ad hoc basis at certain hotspots in the Kech District to respond to cases by the District Administration.

WHO country office (WCO) is supporting the government of Pakistan by undertaking the following response activities:

  • Strengthening of laboratory and hospital-based disease surveillance in all endemic provinces and at the national level, using existing opportunities of Integrated Disease Surveillance (IDS), field epidemiology and dengue surveillance cells.
  • Established data and report collection center at WHO country office
  • Provided required diagnostics kits, medicines, pesticides, and long-lasting nets to ensure the continuity of essential care at all levels, in addition to the provision of long-lasting insecticide treated bed nets for hospital patients in Karachi Sindh province.
  • Trained health care providers from all endemic provinces and districts on the management of dengue cases at various levels of health care delivery system.
  • Provided training on vector surveillance and vector control including source reduction during house visits at the regional level. Trainees included selected entomologists from national and provincial programs and academia.
  • Collaborated with partners and national and provincial health ministries on raising community awareness campaigns by provision of Information, Education and Communication (IEC) material.

WHO risk assessment

Dengue is a viral infection transmitted by mosquitoes caused by four types of dengue virus (DENV) (DENV-1, DENV-2, DENV-3, DENV-4). Infection with one serotype provides long-term immunity to the homologous serotype, but not to other serotypes. Secondary infections put people at greater risk of severe dengue leading to hospital admissions. In Pakistan, dengue fever is endemic with reports of seasonal surges of cases and circulation of the different serotypes (DENV-1, DENV-2, DENV-3, DENV-4) in various parts of the country. Aedes aegypti and A. albopictus are widely adapted vectors for urban and peri urban environments. As dengue is recurrent in the country, the population may be at risk of re-infection and therefore, serious complications if not treated promptly and correctly.

With the current COVID-19 pandemic affecting the national health system capacity, and competing communicable disease outbreaks, there is a high risk of serious health impacts from dengue fever.

This outbreak underscores the need for improved vector surveillance, enhanced laboratory capacity for better case detection, sensitized health care providers on case management and improved surveillance of acute febrile illness in Pakistan to better define disease burden and seasonality patterns.

WHO advice

The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for dengue virus infection. There is no specific treatment for dengue infection, but early detection and access to appropriate healthcare reduces severe dengue and mortality. Furthermore, the prevention and control of dengue depends on effective sustained vector control measures.

WHO promotes the strategic approach known as Integrated Vector Management (IVM) to control mosquito vectors, including Aedes spp. (the vector of dengue) . IVM activities should be enhanced to remove potential breeding sites, reduce vector populations, and minimize individual exposure. This should involve vector control strategies for larvae and adults (i.e., environmental management and source reduction, and chemical control measures), as well as strategies for protecting people and households. Vector control activities should focus on all areas where there is human-vector contact (place of residence, workplaces, schools and hospitals).

Vector control activities may include covering, draining, and cleaning household water storage containers on a weekly basis.

Where indoor biting occurs, application of mosquito repellent lotion or sprays on skin, use of household insecticide aerosol products, mosquito coils, or other insecticide vaporizers are recommended. Household fixtures such as window and door screens and air conditioning can also reduce bites. Since Aedes mosquitoes are day biters (the primary vector for transmission) with peak activity at dawn and dusk, personal protective measures including the use of clothing to minimize skin exposure are recommended. During outdoor activities, mosquito repellents may be applied to exposed skin or to clothing. Insecticide-treated nets offer good protection to people who sleep outside or during the day (e.g., infants, bedridden and night workers) including dengue patients in hospitals and at night to prevent mosquito bites.

In addition, vector and human case surveillance should continue to be enhanced in all affected areas and across the country. Key public health messages on reducing the risk of dengue transmission among the population are expected to continue to be provided. Community based health workers should be sensitized on these key messages to be promoted in all affected areas.

WHO does not recommend any general or trade restrictions to Pakistan based on the information available for this event.

Further information