Fatal Chikungunya virus: Emerging in Nepal

Thus, the time has arrived to take precautionary measures, establishing disease surveillance network, and to develop control and response programs against chikungunya virus in Nepal

Chikungunya virus is an emerging infectious tropical disease in South-Asia and is increasingly reported every year in Nepal. Last year, nearly half a dozen chikungunya viruses were detected in patients with febrile illnesses at Sukraraj Tropical and Infectious Disease Hospital (STIDH). According to the Epidemiology and Disease Control Division (EDCD), at least five patients have been diagnosed with chikungunya viruses this year, and three of them have died. This is the first reported death ever due to chikungunya virus in Nepal. STIDH first discovered chikungunya virus in 2013 in Nepal.

Chikungunya is a viral disease and a mosquito called aedes mosquito transmits the virus while biting a healthy person. It was first described in Tanzania in 1952 and the name itself “chikungunya” derives from Kimakonde language (Tanzanian local language) meaning “to become contorted”.

Chikungunya virus was first recognized in the early 1960s and was last reported in 1973 in India. Thousands of people were reported to be affected by this virus during that time. The virus then re-emerged in 2006 after 32 years as a massive outbreak in India. According to the WHO regional office for South East Asia, more than 1.25 million cases have been reported in India in 2006 alone.

No deaths directly associated with this virus were then reported by the government of India. However, an independent research group who carried out their research during the 2006 in Ahmedabad city found a mortality rate of nearly 12%. In fact, the virus was previously thought to be benign, non-pathogenic and a death from this virus is extremely rare in humans.

It is, thus, of great interest to know how the chikungunya virus is turning into a killer virus. The reason for this is totally unclear, but it is reasonable to assume that mutation may have been occurring, allowing the virus to become more virulent over a period of time.

At present, deaths due to chikungunya virus in Nepal are not clearly understood. Moreover, we even do not know from where and how this virus was introduced into Nepal, and why major outbreaks have not yet  occurred like in India. Nevertheless, it is for sure that we will have to face chikungunya outbreaks someday in the near future, because virus carrier aedes mosquitoes are well established and widespread through southern to north regions of Nepal.

The most common symptom include onset of fever, which is more often associated with severe joint pain. Muscle pain, headache, nausea, fatigue and rash are other signs and symptoms of this virus. Symptoms usually appears 2 to 12 days after exposure, but one third of these infected patients may not develop symptoms.

More than 50% of the patients with chikungunya infection may experience joint pain for months or even years. In Nepal, such patients perhaps might have been visiting rheumatologists in different hospitals. It is becoming apparent that complications due to chikungunya after infection are more common than previously thought.

Eye, heart and neurological complications have been reported before. We have also reported neurological problems in Nepali patients who had been infected with this virus. Very recently, an international research group has concluded that neuro-chikungunya seems to occur more frequently particularly in infants and elderly patients, which is contrary to our previous understanding.

Elderly people, young children below one year, pregnant women and people with chronic medical conditions are particularly at increased risk of having chikungunya related complications and or even deaths, if not promptly recognized and managed. Last year media reported that at least 11 people have been died due to chikungunya complications in India. The great majority of these victims were aged 80 or above and had chronic heart or lung diseases.

The risk for mother to child transmission rate increase up to 50% when the mother has fever during delivery. Babies born to highly viremic mothers can develop symptoms such as fever, rash, irritability, neurological problems, diffuse limb edema etc. Given the apparent increase in deaths associated with chikungunya complications, physicians should include this virus in their differential diagnosis, especially during mosquitoes breeding time, i.e. post-monsoon season in Nepal.

There is neither a vaccine nor a specific treatment available for chikungunya virus. At present, there have been only sporadic chikungunya cases, meaning this virus is now emerging in Nepal. Thus, the time has arrived to take precautionary measures, establishing disease surveillance network, and to develop control and response programs against chikungunya virus in Nepal. The changing nature of chikungunya infection, for example, increasing mortality rate in recent years, is creating new challenges to scientists worldwide. This brings not only challenges but also opportunities to explore new knowledge and discoveries.

To sum up, for the first time, Nepal has witnessed death due to chikungunya virus. Knowing the fact that, the death from chikungunya virus is extremely rare and unusual, research is urgently needed to understand the links between deaths and chikungunya virus in Nepal.

Dr Pun is coordinator of the clinical research unit, Sukraraj Tropical & Infectious Disease Hospital