Dengue Fever: Climate Change Driving the Spread of Disease

By Elliott Levett

A child sleeps underneath a mosquito net in Tanzania (UN Radio)

A child sleeps underneath a mosquito net in Tanzania (UN Radio)

Last month, Tanzania saw a drastic spike in the number of people infected with dengue fever. Although the numbers vary between sources, United Nations Radio claims the disease “has killed three people and infected more than 400”. The health ministry has reported that over 60 patients are currently being treated for the disease in Dar-es-Salaam, and that the most severely affected areas are the Timeke and Kinondoni municipalities, which make up the Southeast and Northwest regions of the city, respectively.  Dengue fever, also known as breakbone fever, has not been a huge problem in Tanzania’s recent history, but the current outbreak is forcing healthcare workers and policymakers to react quickly.

Similar to malaria, dengue fever is spread through contact with mosquitos. Mosquitoes that transmit dengue fever, however, are different from those that transmit malaria because they usually like to feed in the daytime, making mosquito nets less effective. Dengue fever’s symptoms include “fever, headache, muscle and joint pains and a characteristic skin rash that is similar to measles”. In about 10% of cases, however, dengue fever can develop into dengue hemorrhagic fever, which results in “bleeding, low levels of blood platelets and blood plasma leakage”, or dengue shock syndrome, leading to “dangerously low blood pressure”. These deadly conditions are more common among children and young adults.

Since dengue fever is transmitted in the same manner as malaria, and it exhibits similar characteristics upon infection, the disease has caught many Tanzanians off-guard. The Tanzanian government is now acting to ensure citizens are aware of the disease and Doctor Primus Felician Saidia, president of the Medical Association of Tanzania, “urged the public to refrain from engaging in self-diagnosis and taking medication without a doctor’s visit”. Public health officials are afraid that Tanzanians will inaccurately self-diagnose themselves and seek treatment for malaria instead of dengue fever, failing to prevent the spread of the new disease whilst, at the same time, lacking adequate treatment for their infection.

An Aedes albopictus female mosquito obtaining a blood from human host. (AllAfrica.com)

An Aedes albopictus female mosquito obtaining a blood from human host. (AllAfrica.com)

No vaccine currently exists for dengue fever. This is because there are four different serotypes, each serotype must be fought with slightly different antibodies. Dengue fever is unique because infection from one serotype renders the infected person increasingly susceptible to more serious conditions if they are infected by another serotype. Any vaccine that targets only one serotype would encounter the same problem since vaccinations simulate infection. Therefore, government officials are endorsing containment of mosquito populations as the strategy with the highest probable success rate. This means limiting mosquito breeding grounds, preventing mosquito bites, and ensuring a clear knowledge of the range of the disease.

One of the factors that may be limiting complete knowledge of the extent of dengue fever in Tanzania is the high price of testing kits. Private hospitals have been charging two to three times the original price for providing testing kits to Tanzanians. Luckily, the Association of Private Health Facilities in Tanzania (APHFTA) has urged its member hospitals to seek smaller profits in order to cover a wider range of citizens that may be affected by dengue fever. Dr. Samwel Ogillo, head of the APHFTA, says that private hospitals are listening to APHFTA. “”I am glad to say that many health facilities have heard our call and are readjusting their prices”. Public hospitals provide free testing, but now citizens without access to public facilities will have more affordable options for accurate diagnosis.

The recent outbreak of dengue fever is of huge concern to Tanzania, but it is also an issue of global importance. Global warming is increasing the range of mosquito populations, and mosquito-born diseases are spreading alongside. According to a report from the University of Otago in New Zealand, humidity is the “the single climate factor that best [predicts] dengue fever distribution”. The report then asserts, “If humidity were to remain at 1990 levels into the next century, a projected 3.5 billion people would be at risk of dengue infection in 2085, but assuming humidity increases as projected by the Intergovernmental Panel on Climate Change, the authors estimate that in fact 5.2 billion people could be at risk”. This means that, as climate change accelerates, governments will be burdened more and more as dengue fever (as well as other diseases that live in mosquitoes) spreads into new regions. The Temeke and Kinondoni districts have already dedicated $303,000 to dengue fever prevention since the outbreak.

As the effects of climate change start to become more and more tangible and costly, governments across the globe will have to work together to mitigate climate change and help to rectify the negative effects that have and will hurt public health as well as the global economy. If diseases such as malaria and dengue fever continue to spread, more citizens will be unable to work and will burden healthcare systems. The outbreak of dengue fever in Tanzania demonstrates how important it is to couple short term and long term solutions to a problem. Currently, it seems, we have the ability to react to outbreaks when they happen, but we do not have a global consensus to prevent the causes of the spread of these diseases. Without change, I am certain Tanzania will not be the last nation to deal with the onset of a new virus.

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