Not Just COVID-19: Protect Yourself from Avian Influenza, Monkeypox and Dengue Fever during Travel

Dr. ZEE Sze Tsing, Jonpaul

Honorary Consultant in Infectious Disease

Specialist in Infectious Disease

We have all witnessed how much chaos a novel virus can bring to the world during the last 3 years of COVID-19 pandemic. The fact that pandemic is officially over does not mean our fight against infectious diseases is over, especially when all the travels are returning to normal.

Avian Influenza: Rare but Deadly

Avian influenza is caused by a group of viruses circulating among poultry or wild birds. With no immunity against these viruses, humans may suffer from severe pneumonia or even die if infected. Variants such as H5, H7 and H9 subtypes are commonly identified, with H5 being not only active in wild birds and poultry but also transmissible among mammals. Although there have been only a few reported human cases in the past years, the avian influenza virus remains as highly infectious and dangerous as ever.  

With an incubation period of up to 10 days, avian influenza is mostly transmitted through direct or indirect contact with infected animals, e.g. during the slaughter or handling of poultry and wild birds for food production, or via contact with animal droppings and secretions. While human-to-human transmission is rare, one is still at risk of infection when exposed to the respiratory secretions of another infected person if appropriate personal protection equipment is not used.

Currently no human vaccine is available against avian influenza. The best prevention is to avoid close contact with wild birds or poultry.

Monkeypox: Changing Epidemiology Since 2022

Monkeypox (Mpox) refers to an infectious disease caused by the monkeypox virus. With an incubation period of 4 to 21 days, common symptoms include skin rash, blister, fever, headache, muscle ache, enlarged lymph nodes, etc. Mpox used to be endemic to Central and West Africa before 2022, with only sporadic cases reported outside the regions. The primary route of infection is contact with infected animals such as monkey or rodent, mostly related to scratches or bites by wild animals, hunting and handling of animal corpses.

The epidemiology has changed since mid-2022 while clusters of Mpox cases began to emerge in countries outside Africa with no sign of stopping. Most of them are related to sexual exposure between high-risk males.   

The Mpox virus is highly concentrated in skin lesions and body secretion of an infected individual. The virus can invade the body through open wounds, mucus membrane or be transmitted by respiratory droplet. While most patients suffer from mild symptoms and can recover spontaneously without treatment, complications such as encephalitis, myocarditis, etc. may occur in severe cases, especially in individuals with weak immunity.

Mpox is best prevented by avoiding direct contact with wild animals and infected individuals, consuming only well-cooked animal food products as well as refraining from high-risk sexual activities. Last but not least, get vaccinated if you consider yourself at high risk for Mpox.

Dengue Fever: Endemic in Nearby Regions with Risk of Reinfection

With an incubation period of 3 to 14 days, dengue fever is an acute febrile illness caused by dengue virus. The virus is transmitted from person to person by the bites of Aedes mosquitoes. Endemic in the neighbouring regions of Hong Kong, dengue fever is not uncommon among travellers returning from Thailand, Vietnam, Indonesia, Taiwan and Mainland China. Other high-risk areas include Africa, South America and Central America.

Dengue fever is characterised by high fever, severe headache, pain behind the eyes, skin rash, muscle and joint pain. Haemorrhage, shock, or even death may occur in severe cases. Since there are four different dengue virus serotypes, infected persons are susceptible to reinfection in the future.

As no specific antiviral medication or locally registered vaccine is available against dengue fever at present, the mainstay of treatment is supportive. And it is best prevented by elimination of mosquito breeding sites, staying away from mosquito-infested areas and avoidance of mosquito bites with 10-35% DEET mosquito repellents. Mosquito repellents can be applied to skin or clothes, but not eyes or wounds. Repellents should be applied on top of sunscreen if both used together. With an added advantage of flea and tick prevention, DEET is considered safe for babies above 2 months old and pregnant women.

Compared with DEET, other commonly used natural products like lemongrass essential oil, lemon and eucalyptus essential oil, etc. are far less effective in repelling mosquitoes with possible side effects, such as skin allergy, eye and throat irritation, etc.