Tag Archives: Dengue

Using the Internet for More Than Just Cat Pictures

The Internet can be a highly useful tool – communicating with old or distant friends, finding out the latest news, purchasing the latest best-seller, looking at photos of cats, etc. People also go online when they, or someone they know, is ill, searching for information or posting on social media. Your Internet search provider tracks all of this, and this data can be used by researchers to track outbreaks and the spread of infectious diseases. A recent paper by Yang and colleagues [1] demonstrated such a feat with regards to dengue fever.

Dengue is quickly becoming one of the most endemic mosquito-borne disease worldwide, infecting around 390 million people each year in 128 countries,[2] and placing the local health services under immense pressure. The Aedes mosquito that transmits dengue thrives in slums / shanty towns.[3] One of the ways to reduce infection rates is to improve early case detection – identifying outbreaks early means that preventive measures, such as mosquito population control, providing mosquito screens or nets, etc., can be undertaken. However, there is no current surveillance system for dengue that is comprehensive, effective and reliable – governments tend to use reports from hospitals that are often delayed and/or inaccurate.

Yang, et al. combined dengue-related Internet searches with historical incidence data to track dengue activity in five areas, Mexico, Brazil, Thailand, Singapore and Taiwan. They were able to successfully estimate dengue activity one month prior to the publication of official local health records, with their method outperforming benchmark models across accuracy metrics in all areas, except Taiwan. The authors note that Taiwan had little previous dengue prevalence on which to base predictions, suggesting the methodology works best in areas where dengue is already endemic.

— Peter Chilton, Research Fellow

References:

  1. Yang S, Kou SC, Lu F, Brownstein JS, Brooke N, Santillana M. Advances in using Internet searches to track dengue. PLoS Comput Biol. 2017; 13(7): e1005607.
  2. World Health Organization. Dengue and severe dengue. 2016.
  3. Ezeh A, Oyebode O, Satterthwaite D, et al. The history, geography, and sociology of slums and the health problems of people who live in slums. Lancet. 2017; 389: 547-58.
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Infection Sensitisation

A previous News Blog [1] discussed the finding that a previous infection with one strain of Dengue fever can sensitise a person so that infection with a second strain will be more severe than would otherwise have been the case. There is new evidence that such Antibody Dependent Enhancement (ADE) may cross species barriers, such that a person sensitised with one type of flavivirus, say Dengue, is more likely to have a severe illness if inflected with another flavivirus, such as the Zika virus.[2] Such cross species ADE has obvious implications for vaccination programmes. In previous News Blogs [3] we have drawn attention to cross-resistance such that vaccines protect against non-target organisms (e.g. small pox vaccines provide protection against HIV). The above paper shows that the reverse can also occur. This is not the first time that vaccination has been shown to have adverse consequences.[4]

— Richard Lilford, CLAHRC WM Director

References:

  1. Lilford RJ. Three hits hypothesis. NIHR CLAHRC West Midlands News Blog. 7 April 2017.
  2. Cohen J. Dengue may bring out the worst in Zika. Science. 2017; 355(6332): 1362.
  3. Lilford RJ. Two papers try to answer the question – do vaccinations for one communicable disease offer protection against others? NIHR CLAHRC West Midlands News Blog. 27 January 2017.
  4. Guzman MG, Alvarez M, Halstead SB. Secondary infection as a risk factor for dengue hemorrhagic fever/dengue shock syndrome: an historical perspective and role of antibody-dependent enhancement of infection. Arch Virol. 2013; 158(7): 1445-59.