No 29/33 - 2024

Mpox in Africa is Once Again Declared a Public Health Emergency of International Concern

On August 14, 2024, the World Health Organization (WHO) announced that the latest developments in the mpox outbreak in Africa constitute a public health emergency of international concern, as did the Africa Centres for Disease Control and Prevention (Africa CDC), declaring the outbreak a Public Health Emergency of Continental Security on August 13, 2024. There have been reports of mpox spreading from the Democratic Republic of Congo to neighboring countries. No cases of mpox related to the outbreak have been registered in Denmark. Statens Serum Institut is able to detect the infection and has an mpox vaccine stockpile ready to contain any travel-associated cases.

(Department of Infectious Disease Epidemiology and Prevention)

Infection with West Nile Virus in Europe

The European Centre for Disease Prevention and Control (ECDC) monitors the occurrence of West Nile Virus (WNV) infection in Europe. In the latest update from August 12, 2024, an increasing incidence is described, indicating that the WNV transmission season in Europe is well underway.

Up until July 31, 2024, a total of 69 locally-acquired cases were reported from Greece (31), Italy (25), Spain (5), Austria (2), Hungary (2), Serbia (2), France (1), and Romania (1). In total, eight deaths were reported.

The ECDC determined that the overall number of cases is within the expected range, though with more cases in Greece and Spain than usual. There are no signs that the infection is more severe than before, and transmission occurs in known areas where it has been previously documented or in adjacent areas. It is expected that transmission will continue in the coming months as long as weather conditions are favorable for mosquitoes.

WNV infection is transmitted via the bite of the mosquito Culex Pipiens, the common house mosquito, which is also found in Denmark. The infection is most widespread among birds, but mammals and humans can also be infected. Most human cases occur between July and September, corresponding to the period when mosquitoes are most active. Transmission is most widespread in southern Europe and can be tracked on the ECDC’s interactive dashboard. However, there have also been previous detections of WNV transmission to animals in northern Germany and human cases as far north as around Berlin.

Most recently, Polish authorities reported on August 13, 2024 an increasing number of dead crows found in Warsaw since mid-July, with signs of WNV infection found in five of seven examined hooded crows. No human infections have been reported.

Most cases of infection (80%) are asymptomatic, while the typical symptoms are headache, general malaise, fever, vomiting, and fatigue. Less than one percent can develop encephalitis, which can be severe, especially for older people.

Similar to other mosquito-borne diseases, transmission can be prevented by using mosquito repellents, wearing clothing that covers most of the body, and sleeping in air-conditioned rooms (6).

There is currently no vaccine or targeted treatment for humans.

(P.H. Andersen, Department of Infectious Disease Epidemiology and Prevention)

Infection with Oropouche Virus in South America and the Caribbean

Infection with Oropouche virus has been known in the Amazon region of South America for more than 60 years. In 2024, there have been reports of increasing incidence, especially in Brazil, Bolivia, Colombia, and Peru. Additionally, the infection has been detected for the first time in Cuba, from where cases have been imported to several EU countries. Based on this, the ECDC issued a risk assessment on August 9, 2024.

In June and July 2024, a total of 10 cases of the infection were detected in Italy (5), Spain (3), and Germany (2). In total, nine cases had traveled to Cuba and one to Brazil.
Oropouche virus disease is an acute febrile illness with headache, nausea, vomiting, and muscle and joint pain. More rarely, haemorrhaging can occur as well as symptoms of the central nervous system, including meningitis.

The prognosis is usually good and deaths are very rare. Recently, through the PAHO (Pan American Health Organization), there has been a slight suspicion that pregnant women can transmit the virus to the fetus, causing miscarriage, developmental disorders, or malformations, but the risk is currently unclear.

The infection is a zoonosis with its normal reservoir in sloths, monkeys, coatis, rodents, and birds. Transmission occurs via bites and stings from the midge Culicoides paraensis and mosquitoes. The midge is not found in Europe, but it is unclear whether Danish mosquitoes or midges could theoretically transmit the infection. The ECDC has determined that the risk of local transmission in Europe is low. Transmission between humans, including sexual transmission, has not been described, but the risk of vertical transmission from pregnant women to the fetus is, as mentioned, under investigation.

There is no vaccine or specific treatment, and the infection is best prevented by using mosquito repellents on the skin, wearing long-sleeved clothing and long pants, and sleeping under an impregnated mosquito net or in an air-conditioned room.

Oropouche virus disease is a differential diagnosis to other vector-borne infections such as dengue, chikungunya, Zika virus, West Nile virus, and malaria. Testing for Oropouche virus should be considered with relevant travel history plus relevant symptoms and negative diagnostic results for the other viruses/parasites.

Travel Recommendations for Pregnant Women

Until the risk for pregnant women is better understood, precautions should be taken and pregnant women should consider avoiding non-essential travel to areas with known current transmission. The risk areas for Oropouche virus largely overlap with the risk areas for Zika virus. If the trip cannot be postponed until after birth, thorough primary prevention against bites/stings and other preventive measures described above should be adopted.

(P.H. Andersen, Department of Infectious Disease Epidemiology and Prevention, U. Vest Schneider, Virus and Microbiological Special Diagnostics)
August 15, 2024