CLINICAL MATTER
With the Covid-19 pandemic not exactly over, aside from the emergency phase, people still get nervous whenever there is an increase in new cases. Add to this the recent news of a Nipah virus outbreak in India and it is understandable why there is growing anxiety that a new pandemic may be about to start. It is good to be vigilant, but fortunately, there is no strong indication that Covid-19 cases are going to significantly spike anew. It is also improbable that Nipah can give rise to the next pandemic.
Looking at the most recently reported Covid-19 numbers from Sept. 18 to Sept. 24 this year in the Philippines, the number of weekly cases rose slightly by 13 percent to 1,164 cases compared to the week before. This translates to 166 cases a day. There were 10 new severe Covid-19 cases and 11 new deaths reported.
Among the deaths, six occurred in the last two weeks. ICU bed utilization remains below 15 percent. It is important to look at these numbers in the correct context. While there was a nominal increase in cases compared to the week before, these numbers are miniscule compared to the over 30,000 cases and nearly 300 deaths in one day that occurred in January 2022 at the height of the Omicron BA.2 spike. Despite limited supplies of bivalent vaccine boosters, the initial rounds of vaccination and boosting continue to protect us against severe disease from the current circulating variants of Covid-19.
The development of an updated monovalent XBB-based booster provides further insurance against future outbreaks. The updated monovalent vaccine is now available in the US, and the US CDC recommends it for everyone six months and older as a booster. It is unclear when the updated vaccine will arrive in the Philippines and whether the recommendation will be as broad or will only target the most vulnerable populations. In the meantime, newer and potentially more effective types of Covid-19 vaccines are being developed even as surveillance for new variants continues. The possible emergence of new variants with immune escape properties will drive the need for further updated vaccines, but at this time there is no clear answer as to whether and updated vaccine booster needs to be given yearly.
In the meantime, the Nipah virus outbreak in India is making waves in the news. Nipah is a zoonotic virus, transmitted from animals to humans, which was first described in Malaysia in 1998. Nipah refers to the Nipah River in Malaysia near where the original outbreak occurred. The first large Nipah virus outbreak was traced to infections in pigs. It killed more than 100 people. Nipah, along with another zoonotic virus known as Hendra, make up the genus Henipavirus, whose genus name was derived from the combination of the letters of the names of the two viruses in the genus (Hendra and Nipah).
The natural reservoir host of Nipah virus is fruit bats. These typically exhibit few or no symptoms of infection. Incidental hosts include horses and pigs, which are exposed to bat secretions or to fruit that infected bats have partially eaten. These animals can then infect humans through secretions or upon ingestion of contaminated meat. Human to human transmission has been documented as well.
Signs and symptoms of Nipah virus infection include fever, muscle pain, shortness of breath, respiratory distress, headache, confusion, and vomiting. While some patients may only exhibit influenza-like symptoms, the more severely affected patients show signs of encephalitis or brain swelling. Some patients may develop severe pneumonia, which can be fatal.
There has been a well-documented outbreak of Nipah virus in the Philippines. This occurred in 2014 in Sultan Kudarat in Mindanao. Seventeen people met the case definition, including 11 cases of acute encephalitis, five cases of flu-like illness, and one case of meningitis. Nine out of the 17 cases (53 percent) died, all from among those who showed signs of encephalitis. Only two patients tested positive on nucleic acid testing: one from blood on conventional RT-PCR and one from a partial genome from CSF using next-generation sequencing. The rest of patients from whom serum samples were collected were found to have antibodies against Nipah virus.
The main exposures during this outbreak were from equine body fluids when sick horses were slaughtered as well as from ingestion of contaminated horse meat. Five patients who did not have any of these exposures were likely infected by human-to-human transmission. These included two healthcare workers who wore masks and gloves but did not have eye protection (face shields or goggles). Aside from the human fatalities, 10 horses, four cats, and one dog died. Most of the horses showed signs of encephalitis. The other animals were exposed from eating potentially infected horse meat.
Nipah virus outbreaks continue to occur in many countries, including India, Malaysia, Singapore, and Bangladesh. There are nearly yearly outbreaks reported in Bangladesh and India, with high mortality rates. Fortunately, these seem to be limited in scope to no more than a few hundred cases at a time. Transmission typically occurs with close contact, and standard isolation and quarantine protocols are usually able to contain these outbreaks. The current Nipah virus outbreak in India is unusual in that there seems to be a lot of human-to-human transmission, and the World Health Organization is closely monitoring the situation. Currently, there are no reported cases of Nipah virus in the Philippines. Unfortunately, there have been more than a few false alarms fueled by hysteria and panic from fake news.
There is no need to panic. It is true that Nipah virus infection is bad and that we have had it in the Philippines, but that outbreak was contained and it did not spread to other parts of the country. Surveillance by the Department of Health continues, and the lessons we learned during the Covid-19 pandemic are being applied to Nipah and other diseases of pandemic potential.
Proper PPE for our healthcare workers, including eye protection, should be used when investigating these outbreaks. We need to develop more vaccines and treatments against these zoonotic diseases to be better prepared for periodic outbreaks. People who live in rural areas, especially those close wilderness areas should be educated on the dangers of zoonoses. They should be advised not to slaughter and eat sick animals, which can transmit these diseases to humans. They shouldn’t feed the meat from sick animals to their pets either.
All three recent coronavirus outbreaks (SARS, MERS, and Covid-19), including the last pandemic, came from wild animals. We should expect more of these events to occur as humans further encroach into the wilderness. The loss of habitat for bats and other potential carriers of zoonotic infections forces these animals closer and closer to human settlements. Aside from disease surveillance and preparing for potential outbreaks, greater public awareness and education on the dangers of environmental destruction will go a long way toward decreasing the risk of the next big pandemic. Leave the animals alone and their viruses will leave us alone.