Rift Valley Fever: The Next Mosquito-Borne Disease to Fear

Rift Valley fever (RVF) is a zoonotic disease (able to spread between non-human animals and humans). Zoonotic diseases are passed by livestock, pets, and insect vectors like mosquitoes. RVF is caused by a virus and produces symptoms that typically begin with back pain, fever, weakness, and dizziness. About 8 to 10% of people who contract it experience more severe problems, such as brain inflammation, eye disease potentially leading to permanent vision loss, and, in very extreme cases, hemorrhaging and death. The death rate from RVF in humans is around 1%. RVF has severe adverse effects on fetuses and juvenile animals, with almost 100% of infected pregnant livestock experiencing fetal loss. Most juvenile animals that contract RVF die, while adults typically survive. RVF infection may increase the risk of miscarriage and birth defects in humans.

What Causes It?

The Rift Valley fever virus typically spreads when people touch tissue, blood, or other bodily fluids of infected livestock. This occurs during routine care, slaughter, or the consumption of raw or undercooked meat. It is also spread by mosquitoes and other biting insects. The insects don’t themselves become infected with the virus but instead act as carriers, called vectors. Multiple mosquito species spread the disease, typically Aedes and Culex spp. Increased rainfall allows for increased mosquito populations, often leading to outbreaks. Mosquito eggs are viable for several years in dry conditions after being laid. Thus, the virus can lay dormant in these eggs until conditions are right for them to hatch.

The virus first appeared in the Rift Valley of Kenya in the early 1900s. It is most common in eastern and southern Africa, but also found in sub-Saharan Africa, the Middle East, and portions of Asia. However, with modern day world travel, shipping, and trade, there is a greater risk of the disease emerging on other continents such as Europe and the Americas.

How Can I Protect Myself from RVF?

If you live in Europe or the Americas, the chances of contracting RVF are low. However, when traveling to areas in which it is prevalent or if you live in such an area, you should take steps to protect yourself from the disease.

  1. Insect Repellent: One of the simplest ways to reduce your risk of contracting RVF is to use insect repellent. Remember to read the label and reapply at appropriate intervals. Repellents containing DEET, picaridin, and oil of lemon eucalyptus are the most effective. You should also wear protective clothing (long-sleeved shirts and pants, hats, etc.). When sleeping, use a mosquito net.
  2. Avoid Some Areas: Before you travel, read up on current or recent outbreaks. If you can, try not to travel to areas with confirmed active cases. Take precautions and preventative measures if you must go into these areas. Limit time spent outside during peak insect activity times, including particularly humid days when mosquitos are likely to be more active. 
  3. Good Hygiene: If you work with animals, particularly cows, goats, or sheep, make certain that you wear gloves and protective equipment to avoid direct contact with blood or other bodily fluids. This applies to areas in which RVF is know to occur as well as locations with confirmed or suspected cases. In addition, wash your hands and arms regularly. Vaccinate livestock to reduce the risk of an outbreak.
  4. Thoroughly Cook Your Food: You can greatly reduce the risk of contracting RVF by fully cooking meat prior to consumption and only consuming pasteurized dairy products. 

In addition to the major points covered above, routine lawn maintenance to keep mosquitoes out is recommended. Remove any standing water or places that water could collect. Keep weeds and grass trimmed so there are no shady areas for mosquitoes to congregate. When spending time outdoors, stay in a screened porch or use fans to keep mosquitoes away.

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