The Centers for Disease Control and Prevention (CDC) in the US have issued an advisory message to pregnant women. This message states that travel to India is ill-advised as Zika is “endemic” in the country.
The situation with the Zika virus — though seeming dire across October and November — has been deemed by the Indian government to be under control, with no internal travel warnings currently being issued. It is due to this that the current advice of the CDC to avoid the state comes as a shock to the country.
The advisory message suggests that pregnant women should entirely avoid Rajasthan, this is due to the severe birth defects attributed to infections caused by the Zika virus during pregnancy. Further advice suggests travellers should attempt to prevent mosquito bites, as well as use condoms during sex due to the potential for sexual transmission of the virus.
The Indian government responds
The government has made reference to studies undertaken at the National Institute of Virology (NIV), Pune. Critically, the NIV has completed a full genome sequence for the strain of the Zika virus present in India. Upon completion of the sequencing, the NIV has claimed that the gene responsible for causing microcephaly, as seen in the Brazilian strain, was not present in the Indian strain. Furthermore, they found the Indian strain to be significantly less virulent, a fact that may have aided in its containment.
The government has primarily taken issue with the use of the word “endemic” to describe the situation in Rajasthan. They argue that the outbreaks have been few in number and contained to a small number of locations. This would contradict the claim that the disease is endemic to the state as this would require far more widespread and sporadic outbreaks.
The situation in Rajasthan
An outbreak of the Zika virus was reported in the northern state of Rajasthan in October – generating fears of a possible wider scale infection within the city.
A five-member team from the central government was sent to the state capital of Jaipur. This was in response to reports of eight people — including three pregnant women — testing positive for the Zika virus within a short time frame.
In late September, an elderly woman was the first reported case of Zika virus infection in Jaipur. Officials have said this woman cannot be confirmed as the source of the virus within the city as a majority of individuals suffering the infection will remain asymptomatic. This fact makes it difficult to determine the true extent of the outbreak as many people may be infected without realising.
Government response indicates the matter is being taken seriously
The response to the incident has been rapid, with high-level government officials being dispatched to address the issue. The central team included P Ravindran, director of the Emergency Medical Response at the Heath Ministry; Sujeet Kumar Singh, director of the National Centre for Disease Control; and Ashutosh Biswas from All India Institute of Medical Sciences (AIIMS) in Delhi.
Alongside the investigative response there has been an increase in screening procedures to assess the extent of the issue. Since September 25, when the first case of Zika virus infection was reported in the elderly woman, a reported 10,000 families in Shastri Nagar of Jaipur and its surrounding areas have been screened.
Samples of the eight persons were sent to National Institute of Virology in Pune, which confirmed the presence of Zika virus. This is also the case for the elderly woman. She was admitted to Sawai Man Singh Hospital on September 11 with joint pain, redness in her eyes, and weakness. Symptoms such as these are common to a number of infections. She tested negative for dengue and swine flu, at which time the hospital workers suspected a case of the Zika virus and sent samples to Pune for testing.
Difficulties in diagnosis
Diagnosis is often an issue with the Zika virus. As mentioned above many individuals remain symptomless. This can allow for the virus to begin transmission within a population while going almost entirely unnoticed.
Due to the mosquito vector by which Zika is spread, it is capable of rapidly spreading through a population should the circumstances allow for a large breeding population of an Aedes species of mosquito. This type of environment typically occurs during and following the monsoon season in India, where stagnant water in which the mosquitoes may breed is commonplace.
Complications also arise due to the similar nature of the symptoms of Zika to various other infections. Symptoms such as a fever, headaches and vomiting are present in vast numbers of infectious diseases. One feature of the disease — the rash that may be present near the mosquito bite — again suffers the drawback of being a common feature of mosquito and insect vector-borne diseases.
While the Zika virus is rarely fatal in its initial infection victim, the true danger lies in its potential to cause harm in pregnant women. This may be a cause for concern in three of the eight current Jaipur victims who are pregnant.
While the mother will only suffer the symptoms of the initial infection, the baby is at a far higher risk of developing microcephaly – a condition in which the head and brain of the baby are underdeveloped. This often results in the baby only having limited cognitive function. The mechanism by which this occurs due to the Zika virus is thought to be the infection and resultant cell death of neuronal stem cells. Fewer neurons are created, resulting in the reduced brain growth. The resultant microcephaly is the primary reason why the infection is so feared.
How did Zika arrive in India?
The Zika virus has been hitting headlines in recent years and it is quite easy to mistake it as a recent phenomenon. However, the virus was first detected in the 1940s.
The virus was first isolated in its namesake Zika forest of Uganda in 1947. Just a year later, the virus was discovered in a mosquito species Aedes africanus, indicating its circulation among mosquitoes and monkeys. One study believes that the virus was then introduced to the Malaysian-Indonesian region of South-East Asia by the 1950s, after which the virus circulated both East and West, eventually reaching India.
The authors of the study are open to the opinion that the virus may have arrived earlier than this. Lack of surveillance schemes and symptoms easily mistaken to be indicative of other conditions mean the disease may not have been identified.
Currently, India appears posed on the verge of a potential major outbreak if the virus is left unchecked. Rapid and thorough government response to the virus is, however, currently dampening these fears. To avert a greater public health crisis, this must be sustained.