What You Need to Know About Oropouche Virus Disease

The European Centre for Disease Prevention and Control (ECDC) has issued a warning to travelers in areas in South and Central America and the Caribbean affected by a current outbreak of Oropouche virus (OROV) disease. The ECDC said that there had been more than 8000 cases reported in these areas since January, with 19 imported cases reported in Europe for the first time in June and July. Of these, 12 were in Spain, five were in Italy, and two were in Germany. 

The ECDC’s Threat Assessment Brief of Aug. 9 said that one of those affected had traveled to Brazil and the other 18 to Cuba; however, outbreaks have also been reported this year in Bolivia, Colombia, and Peru. Though the overall risk for infection to European travelers to OROV-epidemic countries was assessed as moderate, it was higher in the more affected municipalities of the northern states of Brazil and/or the Amazon region, and/or if personal protection measures are not taken.

An editorial published Aug. 8 in The Lancet Infectious Diseases described OROV as a “mysterious threat,” which there is limited knowledge about despite some half a million cases recorded since it was first detected in Trinidad and Tobago in 1955. 

OROV is transmitted primarily through bites from infected midges (Culicoides paraensis). However, some mosquitoes species can also spread the virus, which causes symptoms very similar to other arbovirus diseases from the same regions, such as dengue, chikungunya, and Zika virus infection. 

Most cases are mild, but meningitis and encephalitis can occur as well as possible fetal death and deformities after infection in pregnancy. Last month, the first fatal cases were reported in two young Brazilian women who, concerningly, had no comorbidities.

This news organization asked Jan Felix Drexler, MD, of the Institute of Virology at Charité – Universitätsmedizin in Berlin, Germany, who has studied the emergence of Oropouche fever in Latin America, what clinicians should know about OROV disease.

What are the main symptoms of OROV disease for which clinicians should be alert?

The main symptoms are not different from other arboviral infections, ie, fever, maybe joint and muscle pain, maybe rash. The problem is that we do not know how often severe disease may occur because we do not know whether the severe cases that have been postulated, including death in apparently healthy people and congenital infection, are due to increased testing; an altered virus; or an altered, more intense circulation (so that many more infections simply lead to rare severe cases appearing). Be alert and ask for testing in your patients. 

What is the differential diagnosis if a recent traveler to affected regions presents with symptoms? Are there any clues to suggest whether the disease is Oropouche as opposed to Zika, etc.?

The main message is: Do not assume a particular infection based on clinical symptoms. If your patient is returning from or living in an endemic area, consider OROV disease in the differential diagnosis.

What personal protective measures should clinicians advise travelers in affected areas to take? Do these differ from normal mosquito precautions?

Repellents are extremely important as usual. However, there are differences. Mosquito nets’ hole sizes need to be smaller than those used against the vectors of malaria or dengue; in other words, they need to have a higher mesh. The problem is that nets with high mesh are complicated in very hot and humid conditions because they also limit ventilation. Travelers should discuss with local suppliers about the best trade-off.

The risk for midge bites is likely highest at dawn and dusk in still and humid conditions. So on the one hand, one could recommend avoiding those areas and being outside during those times of the day. On the other hand, specific recommendations cannot be made robustly because we cannot exclude other invertebrate vectors at current knowledge. Some studies have implicated that mosquitoes may also transmit the virus. If that holds true, then we are back to reducing any bite.

Should pregnant women be advised to avoid travel to affected regions?

Not immediately, but caution must be taken. We simply do not have sufficient data to gauge the risk for potential congenital infection. Much more epidemiologic data and controlled infection experiments will be required to make evidence-based recommendations.

All the cases reported in Europe so far were imported from Cuba and Brazil. Is there any risk for local transmission, eg, via midges/mosquitoes that might hitch a ride on an aircraft, as in cases of airport malaria?

Not immediately, but it cannot be excluded. We know very little about the infection intensity in the vectors. Controlled infection experiments, including robustness of vectors against commonly used insecticides in airplanes, need to be done.

What is the risk for an animal reservoir emerging in Europe?

We do not know, but there is also no reason for ringing the alarm bells. Controlled infection experiments and surveillance will be required.

Is treatment purely supportive or are there any specific agents worth trying in case of severe symptoms/neurologic involvement?

No specific treatment can be recommended as is. However, severe dengue illustrates the relevance of supportive treatment, which is hugely effective in reducing mortality.

The Lancet paper states: “Several laboratory tests have been developed but robust commercial tests are hardly available.” How likely is it that laboratories in Europe will have the capability to test for the Oropouche organism? 

European laboratory networks have already taken action, and testing is now available at least in the major and reference laboratories. If a clinician asks for OROV testing, they will probably get a robust answer in a reasonable timespan. Of course, that can be improved once we have more cases and more laboratories will be equipped for testing.

Is there anything else you think clinicians should be aware of?

The most important is to think beyond the textbooks we know from medical school. Things change rapidly in a connected world under altered climate conditions.

Dr. Drexler has no conflicts of interest to declare.
 

A version of this article first appeared on Medscape.com.

The European Centre for Disease Prevention and Control (ECDC) has issued a warning to travelers in areas in South and Central America and the Caribbean affected by a current outbreak of Oropouche virus (OROV) disease. The ECDC said that there had been more than 8000 cases reported in these areas since January, with 19 imported cases reported in Europe for the first time in June and July. Of these, 12 were in Spain, five were in Italy, and two were in Germany. 

The ECDC’s Threat Assessment Brief of Aug. 9 said that one of those affected had traveled to Brazil and the other 18 to Cuba; however, outbreaks have also been reported this year in Bolivia, Colombia, and Peru. Though the overall risk for infection to European travelers to OROV-epidemic countries was assessed as moderate, it was higher in the more affected municipalities of the northern states of Brazil and/or the Amazon region, and/or if personal protection measures are not taken.

An editorial published Aug. 8 in The Lancet Infectious Diseases described OROV as a “mysterious threat,” which there is limited knowledge about despite some half a million cases recorded since it was first detected in Trinidad and Tobago in 1955. 

OROV is transmitted primarily through bites from infected midges (Culicoides paraensis). However, some mosquitoes species can also spread the virus, which causes symptoms very similar to other arbovirus diseases from the same regions, such as dengue, chikungunya, and Zika virus infection. 

Most cases are mild, but meningitis and encephalitis can occur as well as possible fetal death and deformities after infection in pregnancy. Last month, the first fatal cases were reported in two young Brazilian women who, concerningly, had no comorbidities.

This news organization asked Jan Felix Drexler, MD, of the Institute of Virology at Charité – Universitätsmedizin in Berlin, Germany, who has studied the emergence of Oropouche fever in Latin America, what clinicians should know about OROV disease.

What are the main symptoms of OROV disease for which clinicians should be alert?

The main symptoms are not different from other arboviral infections, ie, fever, maybe joint and muscle pain, maybe rash. The problem is that we do not know how often severe disease may occur because we do not know whether the severe cases that have been postulated, including death in apparently healthy people and congenital infection, are due to increased testing; an altered virus; or an altered, more intense circulation (so that many more infections simply lead to rare severe cases appearing). Be alert and ask for testing in your patients. 

What is the differential diagnosis if a recent traveler to affected regions presents with symptoms? Are there any clues to suggest whether the disease is Oropouche as opposed to Zika, etc.?

The main message is: Do not assume a particular infection based on clinical symptoms. If your patient is returning from or living in an endemic area, consider OROV disease in the differential diagnosis.

What personal protective measures should clinicians advise travelers in affected areas to take? Do these differ from normal mosquito precautions?

Repellents are extremely important as usual. However, there are differences. Mosquito nets’ hole sizes need to be smaller than those used against the vectors of malaria or dengue; in other words, they need to have a higher mesh. The problem is that nets with high mesh are complicated in very hot and humid conditions because they also limit ventilation. Travelers should discuss with local suppliers about the best trade-off.

The risk for midge bites is likely highest at dawn and dusk in still and humid conditions. So on the one hand, one could recommend avoiding those areas and being outside during those times of the day. On the other hand, specific recommendations cannot be made robustly because we cannot exclude other invertebrate vectors at current knowledge. Some studies have implicated that mosquitoes may also transmit the virus. If that holds true, then we are back to reducing any bite.

Should pregnant women be advised to avoid travel to affected regions?

Not immediately, but caution must be taken. We simply do not have sufficient data to gauge the risk for potential congenital infection. Much more epidemiologic data and controlled infection experiments will be required to make evidence-based recommendations.

All the cases reported in Europe so far were imported from Cuba and Brazil. Is there any risk for local transmission, eg, via midges/mosquitoes that might hitch a ride on an aircraft, as in cases of airport malaria?

Not immediately, but it cannot be excluded. We know very little about the infection intensity in the vectors. Controlled infection experiments, including robustness of vectors against commonly used insecticides in airplanes, need to be done.

What is the risk for an animal reservoir emerging in Europe?

We do not know, but there is also no reason for ringing the alarm bells. Controlled infection experiments and surveillance will be required.

Is treatment purely supportive or are there any specific agents worth trying in case of severe symptoms/neurologic involvement?

No specific treatment can be recommended as is. However, severe dengue illustrates the relevance of supportive treatment, which is hugely effective in reducing mortality.

The Lancet paper states: “Several laboratory tests have been developed but robust commercial tests are hardly available.” How likely is it that laboratories in Europe will have the capability to test for the Oropouche organism? 

European laboratory networks have already taken action, and testing is now available at least in the major and reference laboratories. If a clinician asks for OROV testing, they will probably get a robust answer in a reasonable timespan. Of course, that can be improved once we have more cases and more laboratories will be equipped for testing.

Is there anything else you think clinicians should be aware of?

The most important is to think beyond the textbooks we know from medical school. Things change rapidly in a connected world under altered climate conditions.

Dr. Drexler has no conflicts of interest to declare.
 

A version of this article first appeared on Medscape.com.

The European Centre for Disease Prevention and Control (ECDC) has issued a warning to travelers in areas in South and Central America and the Caribbean affected by a current outbreak of Oropouche virus (OROV) disease. The ECDC said that there had been more than 8000 cases reported in these areas since January, with 19 imported cases reported in Europe for the first time in June and July. Of these, 12 were in Spain, five were in Italy, and two were in Germany. 

The ECDC’s Threat Assessment Brief of Aug. 9 said that one of those affected had traveled to Brazil and the other 18 to Cuba; however, outbreaks have also been reported this year in Bolivia, Colombia, and Peru. Though the overall risk for infection to European travelers to OROV-epidemic countries was assessed as moderate, it was higher in the more affected municipalities of the northern states of Brazil and/or the Amazon region, and/or if personal protection measures are not taken.

An editorial published Aug. 8 in The Lancet Infectious Diseases described OROV as a “mysterious threat,” which there is limited knowledge about despite some half a million cases recorded since it was first detected in Trinidad and Tobago in 1955. 

OROV is transmitted primarily through bites from infected midges (Culicoides paraensis). However, some mosquitoes species can also spread the virus, which causes symptoms very similar to other arbovirus diseases from the same regions, such as dengue, chikungunya, and Zika virus infection. 

Most cases are mild, but meningitis and encephalitis can occur as well as possible fetal death and deformities after infection in pregnancy. Last month, the first fatal cases were reported in two young Brazilian women who, concerningly, had no comorbidities.

This news organization asked Jan Felix Drexler, MD, of the Institute of Virology at Charité – Universitätsmedizin in Berlin, Germany, who has studied the emergence of Oropouche fever in Latin America, what clinicians should know about OROV disease.

What are the main symptoms of OROV disease for which clinicians should be alert?

The main symptoms are not different from other arboviral infections, ie, fever, maybe joint and muscle pain, maybe rash. The problem is that we do not know how often severe disease may occur because we do not know whether the severe cases that have been postulated, including death in apparently healthy people and congenital infection, are due to increased testing; an altered virus; or an altered, more intense circulation (so that many more infections simply lead to rare severe cases appearing). Be alert and ask for testing in your patients. 

What is the differential diagnosis if a recent traveler to affected regions presents with symptoms? Are there any clues to suggest whether the disease is Oropouche as opposed to Zika, etc.?

The main message is: Do not assume a particular infection based on clinical symptoms. If your patient is returning from or living in an endemic area, consider OROV disease in the differential diagnosis.

What personal protective measures should clinicians advise travelers in affected areas to take? Do these differ from normal mosquito precautions?

Repellents are extremely important as usual. However, there are differences. Mosquito nets’ hole sizes need to be smaller than those used against the vectors of malaria or dengue; in other words, they need to have a higher mesh. The problem is that nets with high mesh are complicated in very hot and humid conditions because they also limit ventilation. Travelers should discuss with local suppliers about the best trade-off.

The risk for midge bites is likely highest at dawn and dusk in still and humid conditions. So on the one hand, one could recommend avoiding those areas and being outside during those times of the day. On the other hand, specific recommendations cannot be made robustly because we cannot exclude other invertebrate vectors at current knowledge. Some studies have implicated that mosquitoes may also transmit the virus. If that holds true, then we are back to reducing any bite.

Should pregnant women be advised to avoid travel to affected regions?

Not immediately, but caution must be taken. We simply do not have sufficient data to gauge the risk for potential congenital infection. Much more epidemiologic data and controlled infection experiments will be required to make evidence-based recommendations.

All the cases reported in Europe so far were imported from Cuba and Brazil. Is there any risk for local transmission, eg, via midges/mosquitoes that might hitch a ride on an aircraft, as in cases of airport malaria?

Not immediately, but it cannot be excluded. We know very little about the infection intensity in the vectors. Controlled infection experiments, including robustness of vectors against commonly used insecticides in airplanes, need to be done.

What is the risk for an animal reservoir emerging in Europe?

We do not know, but there is also no reason for ringing the alarm bells. Controlled infection experiments and surveillance will be required.

Is treatment purely supportive or are there any specific agents worth trying in case of severe symptoms/neurologic involvement?

No specific treatment can be recommended as is. However, severe dengue illustrates the relevance of supportive treatment, which is hugely effective in reducing mortality.

The Lancet paper states: “Several laboratory tests have been developed but robust commercial tests are hardly available.” How likely is it that laboratories in Europe will have the capability to test for the Oropouche organism? 

European laboratory networks have already taken action, and testing is now available at least in the major and reference laboratories. If a clinician asks for OROV testing, they will probably get a robust answer in a reasonable timespan. Of course, that can be improved once we have more cases and more laboratories will be equipped for testing.

Is there anything else you think clinicians should be aware of?

The most important is to think beyond the textbooks we know from medical school. Things change rapidly in a connected world under altered climate conditions.

Dr. Drexler has no conflicts of interest to declare.
 

A version of this article first appeared on Medscape.com.