Ruzizi Virus

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Your job as a National Institutes of Health (NIH) epidemiologist takes you to Mexico to investigate an outbreak of a deadly re-emerging disease.  Can you find out how the disease is being spread so the outbreak can be contained before more people become infected?


“Another viral outbreak alert? You’re kidding. How many does

Female scientist using microscope to analyze samples.
Analyzing microscopic samples. Image: CDC

this make in the last three months?” You are really not all that surprised. In your work as an epidemiologist at the National Institutes of Health (NIH) you are used to monitoring outbreaks of infectious diseases both inthe U.S. and around the world, but it does seem like they are coming closer together.

Your colleague and friend, Kelly, delivers the news. “We’re being assigned to investigate what might be happening with this virus. It’s not a novel virus, but has all of a sudden popped up in a completely different location than where it occurred before.”

She hands you information from the director on Ruzizi Virus Fever (RVF), some maps of Mexico, and patient interviews conducted by field epidemiologists and tells you that the director wants an analysis as soon as possible.

“OK”, you say to Kelly, “Let’s go through this info and then we can start to plan our next moves.”


After reading the information, you look at Kelly and know you are both thinking the same thing: Ruzizi Virus Fever is a re-emerging disease that seems likely to be a major infectious disease given its rapid increase in the number of cases. You both know that time is a critical factor in containing the outbreak, but without known transmission methods or an effective vaccine, there is little hope of preventing or containing the disease quickly.

Map of location of Chihuahua in Mexico.
Location of the state of Chihuahua in Mexico. Image:

Investigators in the field have already sent you some patient data and interviews so that your team can identify clues that may lead to the transmission method. Somewhere in the patient interviews there are the clues you need to find in order to identify the transmission method of the Ruzizi virus. You know that identifying the transmission method is key to prevention and containment. You also know that a disease can be transmitted in more than one way; identifying each transmission method is important.

The outbreak seems to be centered in the Mexican state of Chihuahua, which shares a long border with the U.S. states of Texas and New Mexico. Given the proximity to the U.S., health officials at NIH and the Center for Disease Control and Prevention (CDC) are concerned that the virus may spread across the border.

Chihuahua has varied climates and ecosystems, including forests, mountainous regions, canyon systems, and wide river valleys. Several river systems allow for farming of a number of different crops. Temperatures vary with the environment, but reach over 100o F in some areas.

Your Task

Review the RVF information and patient interviews for clues to figure out how this disease may be transmitted. Knowing how the disease is transmitted will help identify prevention and control strategies and may possibly allow the outbreak to be controlled quickly.  You know you have to find answers quickly and accurately for your briefing to your colleagues at the NIH and CDC and for public health officials anxiously awaiting some guidance.

Use the following Guiding Questions to help you determine key information about the Ruzizi Virus and to help you prepare your report to the NIH and CDC. Your report should include information about the virus, most likely transmission methods, and prevention and control measures that could limit and/or stop the outbreak from spreading. Be able to support your recommendations with evidence and information on viral diseases and transmission methods.

Guiding Questions:

1) What are the possible transmission methods for Ruzizi Virus Fever given the information in the description and the patient information and interviews? After reading the patient interviews, make a list of every possible transmission method based on patient information.






2) Of course, no official decision will be made until scientific evidence from laboratory testing is available.  However, you can now narrow the transmission methods you listed to the three most likely methods.




3) How could each of the three most likely transmission method be tested to find out if it could be spreading the disease in Mexico?   






4) Which transmission method is your top choice?  You may list more than one if the patient interviews suggest more than one method, but only if you think the two are equally responsible for the spread of infection. Defend your choice.






5) Laboratory testing can take weeks depending on the type of test. Public health officials want to begin prevention, control, and containment measures as soon as possible so new cases and deaths are kept to a minimum. Often, prevention and control measures are instituted before test results are obtained. Based on the transmission methods you have identified, what prevention and control strategies will you and your team suggest to public health officials?






6) Why do you think that only the severe form of the virus and disease is showing up now?