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How Common Are Unexplained Outbreaks Of Disease?

By Zaria GorvettFeatures correspondent@ZariaGorvett

Outbreaks of the Sin Nombre hantavirus are now known to be linked to El Niño, which increases rainfall in the Southwestern US and boosts the rodent population (Credit: Alamy)

Amid reports of a mysterious respiratory illness spreading among children in China, an expert explains how regularly unexplained outbreaks turn up.

It began one spring morning in 1993, when a Navajo family pulled into a service station in New Mexico and dialled 911. Their son, a 19-year-old marathon runner, had suddenly developed breathing problems. He was rushed to the local hospital by ambulance, where he died. The doctors were stumped – what could have killed someone so young and healthy?

It soon transpired that the marathon runner's death was not an isolated incident. He had been on the way to his fiancée's funeral, after she had succumbed to a similar respiratory illness just a few days earlier.

Each time reports of a mysterious new outbreak hit the headlines, there is no shortage of possible suspects. There are more viral particles on Earth than stars in the Universe, and 10 times more bacterial cells in our bodies than mammalian ones. In total, our planet is home to an estimated one trillion species of microorganisms. But only 1,513 types of bacteria, 219 viruses, 300 parasitic worms, 70 protozoa, and 200 fungi are currently known to cause disease in humans. The rest are waiting to be discovered.

What is causing the current respiratory illness in China?

On 13 November 2023, China's National Health Commission reported a spike in the incidence of respiratory diseases, particularly in children. Then more reports began to emerge, describing swamped paediatric units, hospitals overwhelmed with sick children and clusters of undiagnosed pneumonia. Chinese officials have told the World Health Organisation (WHO) that they have not detected any new pathogens, and have instead put the outbreak down to a combination of regular winter illnesses such as RSV and the flu. Some neighbouring countries, such as India, are wary about whether this is the full picture – but the WHO is continuing to monitor the situation.

How common are mystery outbreaks?

"There are clearly some outbreaks that are still mysteries," says Stephen Morse, professor of epidemiology at Columbia University Irving Medical Center in New York.

In the case of the Navajo couple in 1993, the local medical investigator noticed that there had been other cases of this unexplained sickness in the preceding weeks. They had all occurred within the Native American community in the Four Corners region of the south-western US.

With more cases appearing each week, the race was on to catch the culprit. But it would be another two months before it was identified as hantavirus pulmonary syndrome, caused by a totally new kind of hantavirus – a group of viruses which usually infects rodents.

Delays like this are surprisingly common, even today. "There are still a number of infections that go into that general category of undiagnosed acute respiratory distress and things like that which – like the hantavirus pulmonary syndrome – aren't recognised initially but then retrospectively get teased out," says Morse.

Many outbreaks go unnoticed and unreported at first. Morse says that eventually an expert might take a particular interest in an infection, which then leads to an increase in reports. "In other places, there have been a number of outbreaks that that just don't get noticed, because the technical facilities aren't there, because they are remote areas, because there isn't motivation."

Famously, this even happened with Covid-19. In December 2019, the World Health Organization (WHO) was alerted to a cluster of pneumonia cases occurring in the Chinese city of Wuhan – cause unknown. The virus was officially identified within a month, when Chinese authorities shared its genome sequence with the rest of the world. However, some research suggests that the virus actually first began spreading in humans as early as October 2019.

Once an outbreak has caught someone's attention, the next step is actually finding the pathogen behind it.

Outbreaks of the Sin Nombre hantavirus are now known to be linked to El Niño, which increases rainfall and boosts the population of its rodent hosts (Credit: Getty Images)

How are mystery outbreaks solved?

In the case of the 1993 outbreak, the virus responsible was identified using the Polymerase Chain Reaction (PCR), which at the time was a cutting-edge technology. Using specific sequences of DNA from known hantaviruses, scientists managed to find a previously undiscovered member of this group. "It was really the first application of molecular testing to identify the [infectious] agent," says Morse.

Today PCR is a standard method for identifying pathogens, but there is a catch. Because the technique requires a sequence from something closely related to whatever you're looking for, without even a hunch as to the possible cause of an outbreak, it's harder to get an answer. During the Four Corners outbreak, scientists already knew that those who had been infected had antibodies to other hantaviruses, so this is what they used.

However, scientists now also have access to other, more sophisticated methods for finding previously unknown pathogens – and these don't require such specific information. One recently developed method of PCR means it's possible to identify new pathogens within broader groupings. Rather than just being able to look for very close relatives of a known virus, you could find others within the same family.

Another is next-generation sequencing, which can help scientists to find microorganisms that are totally new to science. In one study of a cluster of transplant patients who had died after receiving organs from the same donor, the technique was used to discover a new arenavirus.

"In many laboratories in high-income countries or high-resource settings, you can look at the samples and identify sequences that look like pathogen sequences, whether they're viral or bacterial… without necessarily knowing in advance what's in there," says Morse.

Are the causes of some outbreaks never identified?

In 2010, an unknown haemorrhagic illness began spreading in northern Uganda. "I remember this personally, because I was the co-director of the Predict project," says Morse. There was a delay in researchers from the infection surveillance programme arriving in the area to take samples, he says. But when they did some were positive for yellow fever. "And so it was basically classified as a yellow fever outbreak, but there were negative samples from infected individuals. Presumably it was yellow fever, but we can't say with certainty," he says. Morse cites this as one of many examples of outbreaks with causes that remain an open question to this day.

So, by the time a mystery outbreak hits the headlines around the world, in most cases scientists could be well on the way to finding out what's behind it – but only in areas where they have the resources to do so.

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The Real Story Behind 'White Lung Pneumonia'

Experts say a pneumonia outbreak among children in Ohio and a cluster of pneumonia cases in China are unrelated, despite some social media posts and tabloid articles that have ambiguously linked the two.

The usual respiratory pathogens are making their rounds this cold and flu season, yet the specter of the pandemic has left many on alert for the next novel agent.

"I understand outbreaks in China can make people nervous, but this is not that," says Paul Offit, an infectious disease physician at Children's Hospital of Philadelphia. Although another global illness may emerge in the future, the current pneumonia reports are "nothing to worry about," he adds.

Many pathogens that circulate in the Northern Hemisphere's winter and year-round—including flu, respiratory syncytial virus (RSV) and now COVID—are far from benign and can lead to pneumonia in some cases. But experts say there is no reason to panic or interpret the current uptick in illnesses as anything other than the typical circulation of respiratory viruses and bacteria.

These are "just everyday pathogens that normally increase during the winter having a somewhat early and very assertive increase at the present time," says William Schaffner, an infectious disease physician and a professor at Vanderbilt University Medical Center. But people are not helpless against these germs, says Rama Thyagarajan, an infectious disease and internal medicine physician at the University of Texas at Austin Dell Medical School. COVID, the flu and RSV all have vaccines that can reduce the risk of pneumonia, she says.

Schaffner agrees, calling these immunizations "the best present you can give in this holiday season to yourself and to your family and to your neighbors."

Here's what to know about the recent reports of pneumonia and the term "white lung pneumonia," which has been used in some news coverage to describe the uptick in cases.

What clusters of pneumonia cases are being reported?

Warren County, Ohio's public health department, which serves the northeastern suburbs of Cincinnati, reported a large uptick in the number of typical pneumonia cases in children, with 145 cases in those three to 14 years old recorded as of November 29. Massachusetts has also reported an increase in RSV and "walking pneumonia" among children.

Earlier in November China had reported an increase in respiratory disease cases. Chinese health officials attributed this uptick to the lift of COVID restrictions and the usual rise in known pathogens that can also make people vulnerable to pneumonia, including flu, COVID, RSV and infections caused by the common bacterium Mycoplasma pneumoniae. The World Health Organization is monitoring those cases, as well as an increase in pediatric respiratory disease cases in northern China.

Meanwhile multiple countries in Europe have also reported a rise in pediatric pneumonia cases, many of which are also caused by Mycoplasma bacteria.

None of these clusters, however, appear to be related to one another or caused by unfamiliar bugs. Initial reports on the increase in Warren County came from school nurses who said that a lot of students were calling in sick, according to Clint Koenig, a family physician and the medical director of Warren County Health District.

"We're pretty confident that this is way above what we've seen this time last year," he says. But Koenig adds that it's hard to say how many more cases there are because data on children's pneumonia cases are not routinely collected. Regardless, the causes of pneumonia are no different than those of past years: mostly RSV, adenovirus and Streptococcus or Mycoplasma infections.

What's causing the current uptick in pneumonia cases, and how severe are they?

The growing pockets of pneumonia trace back to the usual increase in respiratory illnesses that occurs every winter, Schaffner says. Just as some flu seasons are more intense than others, the spread and severity of other winter diseases can also vary from year to year. Some upticks might be occurring as the usual seasonality of these pathogens continues to settle back into prepandemic patterns after it was disrupted by lockdowns, masking and social distancing, Schaffner says. But the biggest cause is likely that pathogens have more opportunity to spread in the winter.

"These viruses are taking advantage of us now that we are close together in birthday parties, schools, travel, religious services—whatever brings people together indoors," Schaffner says. "And of course, we anticipate even more of that, given the holiday season. The New Year's parties, all the travel associated with that and vacations are all wonderful environments that predispose to the spread of all of these respiratory infections, some of which will eventuate in pneumonia."

What is the difference between pneumonia, "walking pneumonia" and "white lung syndrome"?

Pneumonia is an inflammation of the lungs that can be caused by a wide range of viruses, bacteria and fungi. Most respiratory infections involve the upper respiratory tract—the nose, throat and upper bronchial tubes, Schaffner says.

An infection develops into pneumonia when it reaches the lower respiratory tract and invades the lung tissue. This causes the lung's white blood cells to trigger an inflammatory response. "If you get a lot of pneumonia, it will materially interfere with your ability to exchange gases. You can get short of breath, and you can have difficulty breathing," Schaffner says.

Other symptoms include cough, fever, chest pain, fatigue and loss of appetite.

At least a dozen different pathogens can lead to pneumonia—no individual pathogen is responsible for even one in 10 cases. In fact, the pathogen behind any particular case of pneumonia is often never identified. Most pneumonia cases are triggered by a bacterium, but pneumonia is also a possible complication of respiratory viruses, such as COVID, influenza, RSV and even the common cold. These viruses can cause pneumonia by themselves or by making the body more vulnerable to secondary infections.

"Once somebody is infected with a virus, they're more prone to get a bacterial infection on top of that" because the viral infection reduces their immune defenses, Thyagarajan explains. "The people that are affected are very young—infants and very young children—and very old and people with chronic illness."

"Walking pneumonia" is a lay term often used to describe mild pneumonia cases, particularly those caused by Mycoplasma bacteria. It also has been called atypical pneumonia, Thyagarajan says, and can cause fevers, a dry cough and sometimes ear infections. According to Offit, "walking pneumonia" is usually not that severe. "Although we treat it with antibiotics, it usually is, for the most part, limited," he says.

"White lung disease," or "white lung syndrome," is nothing but "a scary lay description, not used by medical professionals, of what we see on a routine chest x-ray," Schaffner says. Healthy lungs full of air appear black in an x-ray because air looks dark in a normal reading. When inflammation and white blood cells fill the area, the lungs become opaque and more white on the reading, Offit explains. "It's neither a scientific nor a medically acceptable term," he adds.

How does pneumonia differ between children and adults?

Pneumonia symptoms are similar in children and adults, though young children may also experience nausea and vomiting, and older adults may have confusion. Beyond that, "different bugs are more apt to produce pneumonia in children than adults," Schaffner says. "The older you get, if you have underlying illnesses, these respiratory viruses are more likely to result in pneumonia."

Older adults tend to fare worse with pneumonia. Though pneumonia is the number-one cause of hospitalization in children in the U.S., older adults hospitalized with the disease have a greater risk of death than those hospitalized for any of the other top-10 reasons. That's why it's particularly important for older adults to get their RSV, flu and COVID vaccines, Thyagarajan says. "The populations who are at higher risk for complications, hospitalizations and dying from respiratory viruses and bacteria are the same populations who will benefit most from these vaccinations," she says.

How is pneumonia treated?

Most viral pneumonia can only be treated with supportive care, such as providing oxygen; people with severe cases may require ventilators, heart-lung machines and other forms of mechanical ventilation, Offit says. Bacterial pneumonia is treated with antibiotics.

If you are otherwise healthy, there's no need to contact a health care provider in the first several days of developing a respiratory infection, Thyagarajan says. But if you develop warning symptoms, such as confusion, shortness of breath or a fever that lasts more than three or four days, "it's prudent to call your health care provider or seek emergency care," she says.

Antivirals for flu and COVID, such as Paxlovid, can reduce the likelihood of developing pneumonia when taken early in the course of illness. Those in high-risk groups who develop respiratory symptoms, including those who have a chronic illness or are immunocompromised, should call their health care provider even when the symptoms seem mild, Schaffner says. That way they can get tested for flu and COVID to see if they potentially qualify for medications that reduce the severity of those diseases. Diagnosing an infection and treating it early are key to stopping it from turning into pneumonia.

How can you prevent pneumonia?

Though vaccination can't prevent all cases of pneumonia, five vaccines recommended in the U.S. Can substantially reduce risk of it. Two of these are already routinely recommended for children: the pneumococcal conjugate vaccines (PCV15 and PCV20) and the Haemophilus influenzae (Hib) vaccine. Pneumococcal vaccines are also recommended in adults aged 65 and older, as well as adults with certain medical conditions.

The COVID and seasonal flu vaccines, recommended for everyone aged six months and older, greatly reduce the risk of those diseases developing into pneumonia. Protection against RSV by the monoclonal antibody nirsevimab (Beyfortus) and the recently approved RSV vaccines can also reduce pneumonia risk in those eligible, including adults aged 60 and older, pregnant people, babies and some toddlers.

(Pneumonia develops in one out of five cases of pertussis, or whooping cough, so pertussis vaccination can also prevent pneumonia.)

The same behaviors recommended to prevent the spread of COVID, such as masking, staying home when sick and social distancing, will also reduce risk of other respiratory illnesses that can cause pneumonia.

"If you're in a high-risk group—you're older, you're frail, you have underlying illnesses, you're immune-compromised—you can get out your mask, and you can be more cautious when you travel or go to the supermarket or any indoor gathering of people," Schaffner says.

Thyagarajan says she wears her mask at large gatherings in the winter season to protect herself and to protect others as well. That's especially important if you are a caregiver for an older person or young baby, she adds.

Avoiding people who are coughing and showing other symptoms is obviously ideal, too, but it can be difficult to do, Schaffner adds. Stay home if you are sick—it's ultimately one of the best ways to avoid spreading illness.

Dengue, Cholera And Respiratory Diseases In 2023

Dengue hit the child population hard, mainly.

Santo Domingo—A dengue epidemic that caused tensions in the health system for several months, cholera outbreaks, and a high incidence of respiratory infections, including a new variant of COVID-19, which arrived earlier than expected, colored the epidemiological behavior of the country this year, 2023.

Also, scandals linked to the death of 34 newborns at the San Lorenzo de Los Mina Maternity Hospital, the abduction and subsequent recovery of a newborn baby girl, and the discovery of newborn corpses scattered in a cemetery in Santo Domingo East captured the public's attention. They caused the country's maternity centers to be under scrutiny.

At least six epidemiological alerts were issued this year, including one in May and another in November linked to the risk of diseases arising from flooding as a consequence of atmospheric phenomena; two for an increased incidence of respiratory viruses, including one at the end of December for the presence of the new JN-1 variant of COVID-19; others for advanced cases of measles and chikungunya in the region, although the country did not register any of both cases.

Non-communicable diseases

Non-communicable diseases, such as cardiovascular diseases, diabetes, obesity, traffic events, and mental health conditions, continued to increase in the country amidst voices of concern from specialists.

As part of the actions aimed at strengthening prevention and health promotion and encouraging healthy living and thus impacting these indicators, the Minister of Health intensified his strategy of the "Ruta de la Salud: cambia tu estilo de vida" (Health Route: change your lifestyle), which takes medical and educational care to the different provinces of the country.

This year, 2023, 31 of these activities were completed, and 1,400,000,50 people benefited throughout the country, according to information provided by the Minister of Health, Dr. Daniel Rivera, who heads the activities.

The youngest

The Contact Center "Cuidad tu Salud Mental" of the Ministry of Public Health shows the impact of mental health problems in the country and its attention requirements.

Its latest report indicates that of the 6,377 calls received, 67% are from people between 21 and 40 years old who express sadness, anxiety, anguish, insomnia, and anger, among other ailments, including minors, who constitute 10% of those who demand these services.

Of the calls received at the center, which opened last March 16, to date, 60% correspond to sadness, 50% to anxiety, 49% to anguish, 39% to insomnia, 19% to anger, 17% to lack of appetite, 17% constant worry, 16% suicidal ideation and 14% imitation and feelings of guilt.

Medical conflicts

The conflicts between the Dominican Medical Association (CMD), the authorities of the National Social Security System, and the Health Risk Administrators (ARS) remained latent for a good part of the year.

This led the medical profession to exhaust a calendar of marches, work stoppages, and paralyzations of services to several ARSs, demanding changes in the social security system, including increased health coverage for the population and the rates and fees received for services rendered.

The National Social Security Council (CNSS) recently issued a new resolution increasing coverage and fees.

Last December 8, the CMD changed its board of directors, with Dr. Waldo Ariel Suero assuming the presidency of the guild for the sixth time, replacing Dr. Senén Caba.

Cholera and Covid

The year began with an outbreak of cholera, which spread mainly to different sectors of Greater Santo Domingo. In contrast, in the last quarter, another outbreak was registered in Barahona communities. This year, the country introduced its vaccination with the acquisition of 85 thousand vaccines, which have been applied in high-risk populations through a protocol developed for this purpose.

The COVID-19 virus, although still circulating in the country, maintained a low incidence, except for a slight peak in the number of cases registered this year. At the end of December, the circulation of the new highly contagious JN.1 variant was detected in the country, which prompted the Ministry of Public Health to issue a new epidemiological alert for respiratory viruses.

After over two years of issuing daily information bulletins, the health authorities issued the report once a week last March.

Dengue epidemic

The most significant stress to the hospital system was generated by the dengue epidemic, which continued for several months, especially in Greater Santo Domingo, where the high demand for medical attention exceeded the capacity of the leading pediatric hospitals, forcing the National Health Service (SNS) to set up a network of beds in different health centers.

As of mid-December, corresponding to the 50th epidemiological week, the total number of accumulated suspected cases detected by the system is 24,735, with 23 confirmed deaths, for a case fatality rate of 0.1 percent.

Under surveillance

Reports from the Epidemiology Directorate of the Ministry of Public Health indicate that during the first 11 months of 2023, 116 cases of cholera, 19,467 cases of dengue, 215 cases of malaria, 564 cases of leptospirosis; 23 cases of diphtheria; 29 cases of tetanus in non-neonatal ages; 10 cases of pertussis and six cases of meningococcal disease were reported to the system.

In addition to 150 maternal deaths and 2,700 infant deaths. The National Health Service reports an 11% reduction in neonatal mortality this year compared to 2022, following the implementation of the Neonatal Mortality Reduction Acceleration Plan.

New coverage approved

At the end of the year, the National Social Security Council (CNSS) announced the approval of new coverage, including that of outpatient medicines, which increased from 8,000 to 12,000 pesos per year for members of the Family Health Insurance (SFS) of the Contributive Regime.

Resolution No. 581-03 took this decision, including coverage for 70 new procedures, biopsies, and new approaches to reduce surgical complications and hospital stays.

In addition to an increase in the monthly per capita of the Family Health Insurance (SFS) of the Contributory Regime (RC) of RD$128.08 charged to the People's Health Care Account, from RD$1,555.14 to RD$1,683.22 and a 50% reduction in the co-payment of the SFS of the Contributory Regime for hospitalization services, cesarean sections, surgeries, renal transplants and other high-cost illnesses.

There was a 40% increase in medical fees for procedures, a 50% increase in inpatient consultations, and a 7% increase in diagnostic tests and examination costs. There was also a 15% increase in the use of rooms, equipment, and rooms in clinics and hospitals.

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