With the monsoon’s arrival, dengue virus is being detected in Kathmandu as well as other parts of the country. The bite of Aedes species of mosquitoes, i.e., Aedes Agypti or Aedes Albopictus, transmits the dengue virus to humans. Chikungunya and Zika are other viruses that can also spread through these mosquitoes. Over the past few days, there has been an increase in the number of Zika cases in India.

The presence of the Aedes species mosquitoes is well established in Nepal. Thus, the circulation of the Zika virus in Nepal cannot be ruled out until the suspected cases are routinely tested for it. Here, the suspected case is referred to a patient who has symptoms of dengue-like illness. In fact, dengue-like illnesses have been widely observed in Nepal in the past, especially during almost all dengue outbreaks.

Zika was first noted in Uganda in 1947 in monkeys, followed by humans in 1952. However, a large Zika epidemic in Brazil in 2015 drew worldwide attention due to its connection to neurological birth defects, especially “microcephaly” (small head at birth due to defective brain development) in newborns. In February 2016, the World Health Organization (WHO), thus, then declared Zika as a Public Health Emergency of International Concern (PHEIC). However, it ended nine months after its declaration. In 2016, India reported its first laboratory-confirmed locally transmitted Zika cases (three cases) but without severe complications.

According to the “Journal of Infection,” published in March 2018, a 34-year-old female admitted to a local tertiary hospital for delivery developed a fever with chills and later tested positive for Zika. Two other cases were found infected with Zika during vector-borne disease surveillance. Since then, India has been reporting Zika cases almost every year.

The Indian Council of Medical Research (ICMR) has mandated testing of Dengue-negative and Chikungunya-negative samples for Zika through its collaborative laboratories, including the National Institute of Virology (NIV). This is why India could detect this virus on time/regularly and act/develop plans accordingly. Until a few years ago, Nepal had also established a laboratory testing facility for Dengue-Chikungunya-Zika (combined test) using the Trioplex PCR method. Unfortunately, it has been discontinued for no reason. These three viruses cannot be diagnosed and only be differentiated based on clinical signs and symptoms. Therefore, there is a need to re-initiate the Dengue-Chikungunya-Zika Trioplex PCR testing facility to identify and understand its current status in Nepal. Nowadays, the PCR testing method is commonly used and easily accessible even in private laboratories in Nepal.

Zika also spreads from person to person through sexual contact. An infected pregnant woman can also pass the virus to their fetus. Blood transfusion and organ transplantation can also be the cause of Zika transmission. Nearly 80 percent of people infected with Zika do not show any symptoms. Its symptoms appear three to 14 days after exposure, usually lasting for a week. Mild fever, red eyes (conjunctivitis), rash, muscle and joint pain and malaise are the initial and primary symptoms of Zika. Preterm birth, stillbirth and fetal loss are complications of Zika.

Notably, “microcephaly”, a neurological condition in which an infant’s head is smaller than normal, was found widespread in newborns in the 2015 Brazilian outbreak. A study published in the New England Journal of Medicine in 2019 showed that newborns of women with Zika infected during pregnancy have four to six percent risk of Zika-associated “microcephaly”. Several studies conducted in Nepal have shown neurological congenital disabilities as an emerging health issue, although the cause of defects remains unknown. Contrary to expectation, so far, the Indian Zika strain did not cause “microcephaly” in newborns.

At present, it is not clear why the Zika outbreak in Brazil showed unprecedented neurological defects in newborns, while so far, none has been reported in India. However, both (Brazilian and Indian Zika) genetically belong to the Asian lineage of Zika. The question then arises: Could it be another possibility (non-Zika) or Zika infection with other associated factors that caused “microcephaly” in newborns during the 2015 outbreak of the Brazil virus?

Every year, hundreds of thousands of Nepalis visit India for various reasons. There has been an increasing trend of Zika cases in India each year, triggering the virus transmitting to the Nepalis. After their return to Nepal, there is a high chance of Zika being transmitted to their partners through sexual contact or other activities.

In summary, the monsoon has arrived, and vector-borne diseases such as dengue are on the rise. The vector (Aedes mosquito) responsible for dengue transmission can also spread Zika to humans. Although Zika is not officially confirmed in Nepal, its existence in the country cannot categorically be denied until samples are routinely sent for laboratory testing. The emergence of Zika in India is an urgent call for Nepal to include this virus in routine laboratory testing, preferably during dengue outbreaks or mosquito seasons. Nevertheless, I won’t be surprised if the virus is already circulating in Nepal because the Aedes species are well established here.