Emerging Species of Bacteria:

So Tiny, So Deadly

By Jowi A. Carteciano
Mediacore, NRCP

An outbreak of water and food-borne disease called acute gastroenteritis stormed all 45 towns of Pangasinan last July 22. 

Department of Health Secretary Manuel Dayrit reported that the epidemic downed 2,778 victims in just 45 days or from May 31 to July 16.  Acute gastroenteritis is a human enteric or intestinal disease primarily caused by ingestion of spoiled or bacteria contaminated water or food.

Medical diagnoses of 81 cases showed that cholera, an infectious or transmittable disease was the main cause of the epidemic.

Cholera is caused by bacterial strain known as Vibrio comma, which lives in victim's feces, urine, and vomit and may be transmitted in contaminated water and food.

The DOH's findings confirmed the cause of deaths reflected on the death certificates of 24 Pangasinenses.

The death count may have looked emblematic by Philippine disaster statistics.  But it is indicative of a scarcely understood and mounting deaths caused by different kinds of bacteria via food and water contamination.

Assistant director general Hartwig de Haen of the United Nations' Food and Agricultural Organization said that every year 700,000 people die from food or water borne diseases in the Asia-Pacific region alone, including the Philippines.  De Haen released the information in the May 2004 UN Conference held in Seremban, Malaysia attended by representatives from more than 40 countries.

World Health Organization assistant director general for food safety Kerstin Leitner also said during the conference that the danger of food-related outbreaks is particularly acute in Asia-Pacific region because of higher instances in which animals and people live in proximity along with chancy food production and distribution. 

Microbiology confirms that most of bacteria that trigger enteric diseases live in human and animal wastes.  This and Leitner's testimony could best explain the Pangasinan incident.

Many people in the harder hit towns engage in backyard swine and poultry raising.  Other than proximity to animal dwellings, the victims most likely had unclean households, surroundings, and practiced improper handling and cooking of foods.

Floodwaters kicked off by super-typhoon "Igme" probably made the epidemic worst as it abetted transmission of the dreaded bacteria. 

If the Pangasinan incident was hard enough to contain, health authorities may have to scramble for better and effective ways to combat emerging virulent species of bacteria

Three Filipino medical microbiologists in a research entitled "The Emerging Foodborne Bacterial Zoonoses" provide more than a clue.  The research scientifically proved that the UN-FAO's and WHO Food Safety death counts on water and food-borne diseases were connected with the rise of virulent microorganisms.  The study was cited by internationally recognized researches.

The University of the Philippines College of Public Health funded the research and was published in volume 131, June 2002 issue of the Department of Science and Technology's Philippine Journal of Science.

For the most part, the research shows that the rise of virulent microbes poses more serious health problems with high mortality rate.  Four emergent bacteria are comparatively more toxic than two well-known bacteria -- the Salmonella spp. and Escherichia coli.

The microbiologist--researchers, Dr. Alice-alma C. Bungay, Dr. Methusyla J. Estacio, and Dr. Calvin S. Delos Reyes identified the emergent pathogenic bacteria as Listeria monocytogenes, Campylobacter jejuni, Yersinia enterocolitica, and the E. coli O157:H7 - an emerging strain of Escherichia coli. 

Dr. Bungay, the research team leader said that unprecedented change in microbial population triggers the emergence of the four micro-organisms that leads to their evolution--more virulent, stronger, and dangerous.  These newly evolved micro-organisms dubbed as superclaps by 1993 Puitzer Prize winner for science journalism Mike Toner, already acquired a very strong resistance against commercially available antibiotic drugs.

In a worst-case scenario, the research team said, the superclaps could set off pestilence such as listeriosis (malfunctions of human immune system), acute gastroenteritis (characterized by severe diarrhea), hemorrhagic colitis (inflammation of intestines), and uremic syndrome (blood disease causing accumulation of toxic waste products in urine).

Understanding the superclaps may help health authorities in building a defense plan.

Listeria monocytogenes
Listeria monocytogenes   primarily lives in warm-blooded animals and their surroundings.  This bacterium is also frequently present in processing plants environment where it can establish endemic or dominant strains.

The research team noted that raw foods, improperly and uncleanly kept inside processing plants, are considered to be powerful sources of bacterium contamination.  Bungay said that it would not only contaminate other kinds of food being processed but the processing equipment as well in a process called cross-contamination. 

On the other hand, human Listeria monocytogenes infections start from its entry through the mouth by means of ingesting or eating contaminated food or drinking contaminated water.  When contaminated food or water is dissolved in the digestion system, the bacterium will find its way from intestines to the cells.  While it lives inside the host's cells, the bacterium can counteract the impacts of the infected cells' immune system. It thus multiplies rapidly and infects the surrounding cells causing disease infection known as listeriosis.

People with very poor immune system or immunocompromised, like those considered "senior citizens", are susceptible to food-borne listeriosis.  Clinical manifestations from an elderly diagnosed with listeriosis infection include blood poisoning (septicemia), inflammation of spinal cord's protective covering (meningitis), inflammation of the brain (brain stem encephalitis), and accumulation of pus in the liver (liver abscess).

The research also noted that pregnant women should be very cautious in eating improperly processed or cooked food like milk, Mexican style cheeses, meat and meat products, half-cooked vegetables, vegetable salads including coleslaw.  The 1991 listeriosis outbreak in North America and Europe were traced to such foods contaminated with the bacterium.

The research warns that abortion and stillbirth might occur if pregnant women got infected with food-borne listeriosis.  Modern antibiotic therapy seems to be ineffective as cure for treating neonatal listeriosis (infected 60 day old infant in the mother's womb).  Neonatal listeriosis infection has mortality rate as high as 36%.

The researchers further explained that the first recorded cases of listeriosis outbreak ccurred in the country in the early 60's.  However, local medical researchers and scientists at the time did not fully document the mode of its transmission. 

To date, although cases of outbreaks in other Asian countries are sporadic and more frequent than in previous years, not much studies and investigations were made to fully understand water and food-borne listeriosis, the research team added.

Campylobacter jejuni
Campylobacter bacterium has two species, which are said to be the cause of campylobacter enteritis.  These are Campylobacter coli and Campylobacter jejuni.  The latter was found to be more prevalent especially in poultry products and unpasteurized milk.

Campylobacter jejuni, being more prevalent is now recognized to be the main cause of human campylobacter enteritis disease, which is characterized by acute diarrhea that lasts for five days.

Early manifestation of the human campylobacter enteritis infection is fever.  This is followed by experience an attack of Guillian--Barre Syndrome or GBS, characterized by body weakness, muscles and bone joint pains that goes on for several days.

Transmission of this disease, according to related research is basically zoonotic in nature, that is, the disease is acquired by or transmitted to human through direct consumption of infected animal meat (cattle, swine, chicken).  Majority of infections recorded are traced to improper handling and cooking of foods of animal origin.

Bungay clarifies that campylobacter enteritis disease is essentially a food-borne zoonosis, which means that the principal vehicle or carrier of infection is raw or undercooked meat.  Any kind of animal meat is likely to be contaminated with the bacterium.  Poultry products especially broiler chickens are said to be the main source of the microbes.

To meet huge demand for chicken meat, she said, mass mechanized processing is done.  In this process, cross-contamination occurs especially if the chickens' cecum, a pouch like section of the chickens' intestines where thousands of Campyobacter jejuni bacteria live, were mishandled or improperly disposed during mass processing.

Yersinia enterocolitica
Yersinia enterocolitica mostly affects older people with weaker immune system.  This bacterium primary causes mesenteric lymphadenitis or the tearing down of the covering of the part of the intestine that connects it to the abdomen.  This leads to severe abdominal pain sometimes mimicking the manifestations of acute appendicitis.  In some cases, severe diarrheal attacks are experienced, manifestations similar to those with cholera enteric disease caused by Vibrio comma bacterium that recently hounded Pagasinan.  Both disorders may be complicated with reactive arthritis or inflammation of bone joints.

A 1992 WHO report confirmed the emergence of this bacterium and the infections associated to it.  The same report said that infections occurred in European and other developed countries like Canada and US.

Although the report noted that outbreaks of Yersinia enterocolitica related disease occurred only in countries with moderate to cold climates, other reports showed that the bacterium has been isolated and identified in tropical and developing countries like Nigeria, Singapore, and the Philippines.  The bacterium could be the "causative agent" of undiagnosed diarrheal cases of two kids admitted in the Philippine General Hospital in 1997, the research team hypothesized.

The research also added that yersiniosis is a diarrheal disease caused by Yersinia enterocolitica.  It is also linked to the consumption of undercooked pork, sausages, beef, pork, chicken, untreated water, and other variety of foods such as milk and milk products, and vegetables.

The researchers also cited a related research that found high incidence yersiniosis infection is associated with pork consumption.  Essentially, it places pork-chowing Filipinos as high-risk cases.

The University of the Philippines Department of Medical Microbiology in collaboration with the Department of Agriculture's National Meat Inspection Commission did preliminary study on this bacterium.  The study that involved leading slaughterhouses in Metro Manila revealed that out of 384 freshly slaughtered pigs, 14 were found to be positive of infection or contamination of the said bacterium.

Escherichia coli O157
The research also said that among the species of Escherichia coli, the emerging strain considered as enterohemorrhagic-causing species is the Escherichia coli O157 (E. coli O157).  It is the most virulent.

Like the other three emergent bacteria, this bacterium severely infect humans with high mortality among the elderly.

This species of bacterium has been associated with numerous worldwide outbreaks and sporadic infections to humans that range from uncomplicated diarrhea to hemorrhagic colitis to hemolytic uremic syndrome.

Although some recorded outbreaks of human E. coli O157 infection were frequently linked with the consumption of undercooked minced beef, recent records show that water and food-borne outbreaks as well as person-to-person transmission are increasingly being recognized by international researches.

The latest list of foods, which the research identified to have direct and indirect evidence of being used as vehicles of the E. coli O157 bacterium for transmission include  beef, pork, lamb, chicken, turkey, sausages, salami, hamburgers, fish, shellfish, vegetables, milk, yoghurt, cheese, apple cider, and water. 

However, the process of contamination by the bacterium has yet to be established.  Other risk factors were identified such as direct contact and consumption of carrier animals and surface water like accidental drinking of contaminated water from swimming pools, rivers, and other recreational facilities.

From time to time, outbreaks caused by different superclaps are expected to arise with massive impacts on food safety and public health.   In a developing country like the Philippines, information can only be the first defense.

The threat of superclaps cannot be underestimated and the need to develop active surveillance systems should be one of the government's priorities, the researchers concluded.