Save the Big Guns for the Big Battles

Our bodies war with the microbial world. Microbial invaders seek to invade and sap our power. They produce toxins (proteins in most cases) that destroy our cells and cause damage. These bacteria are toxin manufacturing plants and oftentimes contain more toxin inside themselves than they release into their environment. Our immune system responds to these invaders by sending white blood cells called polymorphoneutrophils or PMN’s. PMN’s gobble up (phagocytosis) the invaders and slowly destroy them. The toxins are inactivated and destroyed within the PMN’s and very little fallout occurs when our immune system destroys bacteria. When our immune systems are overwhelmed bacteria start winning the war. To stop this we use antibiotics to destroy these nasty microbes. Antibiotics buy our immune systems valuable time to recruit other members of our immune system to join in the fight. Unfortunately, using antibiotics can cause damaged and dying bacteria to release their toxins too quickly. Not enough PMN’s are around to gobble up these microbes and damage can occur to the patient.

Sometimes we get too hurried and want the antibiotics before they are necessary. Overkill with antibiotics can sometimes be worse than just giving our immune systems time to contain and eliminate the infection. Diarrhea due to bacterial invaders is a case in which we sometimes bring the big guns (antibiotics) out too soon. Most diarrheal infections can be resolved by our immune systems. The only treatment necessary is to keep the patient from dehydrating. This can be done by giving the patient plenty of fluids.

Recently, a study funded by the National Institute of Diabetes and Digestive and Kidney Diseases (an institute at the National Institutes of Health, USA) demonstrated that bringing our the big guns, antibiotics, too soon can be life threatening. They showed that antibiotics given to children as a treatment for diarrhea caused by Escherichia coli O157:H7 results in more problems than not treating the infection with antibiotics. These researchers studied 71 children who were infected with Escherichia coli O157:H7. Of the 9 who received antibiotics, 5 (56 percent) developed hemolytic uremic syndrome or HUS, compared with 5 (8 percent) of the 62 who developed HUS in the group that did not recieve antibiotics.

By giving these children antibiotics the bacteria were rapidly killed. This rapid killing of the bacteria resulted in large amounts of toxin being released to the kidneys. The kidneys were damaged by the toxin and unable to function properly resulting in HUS. From 3-5 percent of children with HUS die and of the survivors 10-40 percent suffer from permanent kidney damage.

Bringing out the big guns too soon can cause more harm than good. Antibiotics

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Iron Poor Blood Doesn’t Hurt Lyme Bacteria

One important part of our diet is iron. Iron is a metal that is very important in helping us get energy from our foods. Without adequate amounts of iron we will become very tired and eventually very sick. That is because iron is involved in the end stages of energy production. For example when our bodies breakdown sugar we end up giving off lactic acid, carbon dioxide, water, and storable energy in the form of ATP (adenine triphosphate). When needed the ATP will breakdown to ADP (adenine diphosphate) releasing this stored energy. To get the most ATP out of each sugar molecule we use iron containing molecules called cytochromes. Without these cytochromes our bodies would soon lack the energy needed to survive.

Iron also transports oxygen to the cells of our bodies via our red blood cells when attached to a protein called hemoglobin. We need to live in an oxygen environment because oxygen is also involved in the end stages of ATP production. Oxygen accepts the leftover electrons from sugar breakdown and with a couple of hydrogen atoms makes water. Water is a byproduct of sugar breakdown and energy generation. Our bodies consider iron such a precious metal that it produces iron binding proteins that hold on to any extra iron that maybe in our bodies.

We are not the only ones that need iron to survive. Most bacteria also need iron to live. They, like us, use iron to help in generating ATP. Bacteria have developed very elaborate means to get iron from the environment so they can survive. In fact the iron binding proteins in our bodies are important in preventing many bacterial illnesses. If all the available iron is bound to these proteins many bacteria simply die of ATP starvation. To get around this particular defense mechanism most bacteria that infect humans produce compounds that grab the iron from our iron binding proteins.

The Lyme disease bacterium has developed another way around this problem. It does not need iron at all. Researchers at the University of Georgia have discovered that the Lyme disease bacterium, Borrelia burgdorferi, only has 5 molecules of iron per cell. If given too much iron it will die. It enjoys iron-free environments. Instead of using iron to generate ATP it uses manganese. Without the need for iron this particular bacterium doesn’t have to fight with our iron binding proteins to survive and can live quite well in our bodies for long periods of time.

This ability to live without iron is very rare. Only one other bacterium, Lactobacillus planatarum, has been identified that doesn’t need iron to live. This knowledge may help Lyme disease researchers better understand how this organism causes disease and may also help in the design of antibacterial compounds that could kill these unique microorganisms. Life can be very interesting. You think you have it all figured out and POW some microbe or another does things just a little bit differently

Treatment of Hepatitis C Infections Possible in AIDS Patients

One million people are infected with the AIDS virus (HIV) and 4 million people are infected with the Hepatitis C virus in the United States. Hepatitis C infections are currently the leading cause of liver transplants in the United States. Scientists don’t foresee a bright future. Many people are carrying the virus around in their livers and don’t even know it. Hepatitis C virus infection typically takes 2-3 decades before it starts causing significant liver damage. The most common means of getting Hepatitis C virus infections is via needle sharing by intravenous drug users. Around 350,000 patients are infected with both HIV and Hepatitis C viruses. The fact that people were coinfected with both viruses was not a big problem before combination therapy for AIDS was initiated. HIV infected patients typically would die of AIDS before the Hepatitis C infection had time to destroy their liver. With the advent of combination therapy for AIDS physicians are seeing patients die not of AIDS but of their Hepatitis C virus infections. It also has been shown that disease in patients with both viral infections progresses more rapidly than in patients with just one of these viral infections. The Hepatitis C virus is causing liver damage and so do some drugs used to treat the HIV infection. These dual causes of liver damage make it very difficult to treat patients for the HIV infection.

To see if treatment of the Hepatitis C infection and HIV infection could be given at the same time researchers at The Cabrini Institute for Virologic Care gave treatments for both viral infections to patients infected with both of these viruses. These patients were given interferon alfa-2b and ribavirin to treat the Hepatitis C infection and combination therapy for the HIV infection. When evaluated a year later the researchers found that both viruses were at undetectable levels in the patient’s blood. This is a great finding. They did not cure these patients. Many studies have demonstrated that viral levels in the blood rise again once drug therapy is stopped.

This will however help patients with both of these viral infections to live longer and better lives. This work also confirms previous work that the combination therapy (interferon alfa-2b and ribavirin) for Hepatitis C virus is better in treating Hepatitis C infections than just using interferon alfa-2b alone.

What is in those Vaccines: Part VII?

Chickenpox (varicella) is a common childhood illness. Almost every child has gotten it by age 10. It is very contagious. You don’t have to even touch a skin lesion to get the disease. It can be spread in the air from person to person. In fact some parents I have known have taken their children to a home with a child that has the chickenpox in hopes their children will get it. They do this knowing that getting chickenpox as a child is a much milder disease than when they are older. Adults who get the chickenpox can develop some very serious and life-threatening complications. Why this happens I don’t know, but this is common for a number of viral diseases. Chickenpox is caused by a virus called the Varicella-Zoster Virus. When a person gets this virus they have it for life. Sometimes it comes back to cause problems later in life. A disease called the shingles (Zoster) is common in elderly people or people with suppressed immune systems. This diseases begins with severe pain and tenderness usually around one side of the rib cage (although it can occur anywhere). In a day or two redness develops over the area of pain and eventually fluid filled bumps develop (the classic chickenpox lesion). Unfortunately, this illness doesn’t go away as rapidly as the chickenpox and can result in long term pain for some people.

Since the chickenpox is not acquired by every child and the complications associated with acquiring this virus later in life can be very severe researchers have developed a vaccine. This vaccine contains a live Varicella-Zoster Virus that can not give you the disease but can trick your immune system into thinking you have the chickenpox. As a result it protects you from getting the chickenpox. It does not protect you from getting shingles. It is currently recommmended for any child over one year of age that does not have evidence of having already gotten the chickenpox.

This vaccine could also be given to anyone over the age of 13 that does not have any evidence of having gotten chickenpox. There are exceptions to this rule. If you are pregnant or have a suppressed immune system you should not get this vaccine. Live viral vaccines should not be given to pregnant women for fear of infecting the baby. Immunosuppressed (chemotherapy patients, AIDS patients, patients getting corticosteriods (prenidsone)) should not get live viral vaccines because the virus although wimpy could cause serious infection in people with poor immune responses. Think of it this way. Even a child can break in to a house when the doors are wide

Our Hamburgers are Contaminated!

Previous estimates by the United States Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS) calculated that about 5 percent of the hamburger processed in the U.S. was contaminated with Escherichia coli O157:H7.
This particular bacteria causes about 62,000 cases of food poisoning in the United States each year. Infection with this bacterium is especially dangerous to the elderly, the young, and the immunocompromised. People in these categories can experience bloody diarrhea and kidney failure. A recent report by the FSIS using a much more sensitive test indicated that almost 90 percent of the hamburger lots tested were contaminated with Escherichia coli O157:H7. This is not good news. However, you must take some of this alarming news with some amount of cautious examination. Some of those lots of hamburger only contained 100 Escherichia coli O157:H7. Those lots consist of 3000 pounds of hamburger. If you were to eat a quarter pound burger and if the Escherichia coli O157:H7 were evenly distributed you would have to eat 120 uncooked quarter pound hamburgers to get one organism. The dose of Escherichia coli O157:H7 needed to cause illness is about 10 organisms. This means that you would have to eat 1200 uncooked quarter pound hamburgers to get sick.

I don’t want you to think that I am downplaying the importance of these findings. Not all hamburger is kept at the proper temperature to prevent growth of the bacteria. One hundred organisms could quickly become 1 million organisms. Nor are bacteria evenly distributed in the meat. Some poor unfortunate person may get the only undercooked hamburger from the lot with 10 Escherichia coli O157:H7 in it and get really ill. Many of the lots of the hamburger FSIS tested contained much higher numbers of Escherichia coli O157:H7 in the meat. The bad thing about these bacteria is that you can NOT tell if the meat is contaminated. It will look fine and smell fine. However, if you do not cook it properly and are at the right age for serious complications you could become very ill.

The take home message of this story is that most hamburger packages you get from the store are contaminated with disease causing bacteria. Many people love to eat hamburger. You should not stop eating hamburger but instead you should prepare it wisely and cook it until it is well done.

You don’t have to be an unknowing victim of contaminated hamburger. Most food poisonings do NOT occur in restaurants. It is just that those outbreaks of food poisoning are more likely to be reported to the public. Uncle Bill’s Saturday night hamburger feast with four of his friends

Alcohol with Less Severe Hangovers Created: New Scientific Discovery Reduces the After-Effects of Drinking

Most people at some point in their lives can recall a time when they have had ‘one too many’ and suffered the next day from the effects of alcohol. A team of scientists in Korea may now have found a solution to stop those ‘morning after’ feelings.

Alcohol with a Higher Oxygen Content Produces Fewer after Effects

A team of scientists from Chungnam National University in Korea carried out experiments where participants were given alcoholic drinks with varying oxygen content levels. Results showed that those participants who had greater levels of oxygen within their drinks sobered up significantly quicker than those with lower levels in their beverages.

According to The Telegraph newspaper, when a person drinks alcohol, Oxygen in the body turns the alcohol into water and carbon dioxide. The study in Korea found that when Oxygen concentrations in alcoholic drinks are increased, it would appear that the process of the human body dealing with alcohol and breaking it down is speeded up.

The Common Hangover

The effects that alcohol will have on a person varies between individuals. Some people have a higher tolerance to alcohol than others and factors such as a person’s height, build and age can also lead to how well the body deals with the consumption of alcohol.

According to http://www.howstuffworks.com, other physical factors such as;

  • How tired a person is before drinking alcohol,
  • How much they have had to eat before drinking alcohol,
  • how well hydrated they are beforehand, and,
  • Level of physical activity a person does whilst drinking alcohol ,

Can all affect how a person responds when consuming alcohol; this is one of the reasons why individuals find their tolerance to alcohol varies depending on their situation when consuming an alcoholic drink. Those people who have been dancing at the same time as drinking may find that they suffer more severe hangover the next day due to the added effects of dehydration that the dancing caused.

Scientists don’t fully understand all the causes of hangovers but the primary symptoms including headache’s, nausea and vomiting result from a combination of various chemical imbalances being caused in the body by alcohol being absorbed (www.howstuffworks.com).

Hangovers won’t be a Thing of the Past

The new alcohol developed by the Korean University won’t mean that those consuming it will feel no effects at all. The scientists point out that their work won’t lead to hangover free alcohol but could lead to alcohol that has the same level of alcoholic content but owing to its higher levels of oxygen, creates less severe hangovers.

The full results of the experiment can be read in the Alcoholism: Clinical and Experimental Research.

Traveler’s Diarrhea: Risk and Associated Pathogens

Traveler’s diarrhea is characterized by the onset of loose, watery or semi-formed stools, of an urgent nature, accompanied by abdominal cramps. Vomiting may also accompany diarrhea (15% of cases). Symptoms may be preceded by flatulence and abdominal cramping. The illness is usually self-limited lasting 3-4 days.

Traveler’s diarrhea is most commonly caused by bacteria (85%), but can also be caused by parasites (10%) and viruses (5%). The risk of acquiring traveler’s diarrhea is dependent on your travel destination. Countries are classified as low-risk, intermediate-risk and high-risk (see Map). The Centers for Disease Control and Prevention (CDC) estimated that 30-50% of travelers will develop traveler’s diarrhea during a 1- to 2-week stay in high-risk areas.

Risk of traveler’s diarrhea varies seasonally in temperate climates, listed in the dictionary of biology.

Low-risk countries:

  • Canada
  • United States
  • AustraliaNew Zealand
  • Japan
  • northern and western Europe.

Intermediate-risk countries:

  • Eastern Europe
  • South Africa
  • Caribbean Islands

High-risk countries:

  • Asia
  • Middle East
  • Africa
  • Central and South America

Ingestion of contaminated food or water is responsible for most cases of traveler’s diarrhea, and most of these are caused by bacteria. A number of different bacteria may cause traveler’s diarrhea:

Enterotoxigenic E. coli (ETEC):

  • large inoculum required to produce illness,
  • associated with sanitation breakdown,
  • common in developing countries,
  • symptoms include watery diarrhea and cramps,
  • fever, if present, is low-grade.

Enteroaggregative E. coli (EAEC):

  • responsible for up to 25% of cases of traveler’s diarrhea,
  • symptoms similar to ETEC-associated illness.

Campylobacter jejuni:

  • commonly associated with diarrhea in developed countries,
  • much more prevalent in developing countries,
  • most of Asia is considered high-risk,
  • symptoms include blood diarrhea and fever.

Salmonella spp.

  • commonly associated with foodborne outbreaks in developed countries,
  • infrequent cause of traveler’s diarrhea.

Shigella spp.

  • common cause of traveler’s diarrhea,
  • low infectious dose required for illness,
  • symptoms include diarrhea (may be bloody), abdominal cramps, and fever.

Vibrio spp.

  • Vibrio parahaemolyticus and non-O-group 1 Vibrio cholerae,
  • associated with eating raw or partially cooked seafood.

Protozoan parasites account for approximately 10% of cases of traveler’s diarrhea. Onset of illness is usually less abrupt than with bacteria-associated traveler’s diarrhea, and symptoms are often persistent.

The most common parasites responsible for traveler’s diarrhea include:

Giardia lamblia:

  • intestinal flagellate,
  • associated with ingestion of contaminated surface water associated with poor sanitary conditions,
  • foodborne outbreaks resulting from contamination of food by infected food-handlers,
  • person-to-person transmission occurs due to poor fecal-oral hygiene,
  • environmentally resistant cyst form shed in feces,
  • incubation period 12-19 days,
  • common symptoms include diarrhea, weakness, weight loss and abdominal pain,
  • less common symptoms of nausea, vomiting, flatulence and fever,
  • illness usually self-limiting, lasting 2-4 weeks.

Cryptosporidium parvum:

  • common intestinal pathogen worldwide,
  • associated with contaminated drinking water and recreational water,
  • average incubation period of 7 days,
  • watery diarrhea most prominent symptom,
  • frequent and copious bowel movement can cause dehydration and weight loss,
  • symptoms include nausea, abdominal cramps, vomiting and mild fever,
  • environmentally resistant oocysts shed in stool for at least 2 weeks following illness.

Cyclospora cayetensis:

  • associated with ingestion of contaminated water and food,
  • incubation period 2-11 days,
  • symptoms include watery diarrhea, fatigue, abdominal cramping, anorexia, weight loss, vomiting, low-grade fever, and nausea,
  • illness may last for weeks with episodes of watery diarrhea alternating with constipation,
  • environmentally resistant oocysts shed in feces for up to 60 days.

Giardia lamblia, Cryptosporidium parvum and Cyclospora cayetensis are endemic parasites in supplies of drinking water throughout the world. All three have been found in most surface waters with concentration related to the level of fecal pollution. The cysts (Giardia) and oocysts (Cryptosporidium and Cyclospora) are resistant to environmental conditions and disinfectants, although boiling water for 10 minutes is sufficient to kill cysts and oocysts. Additionally, relatively low numbers of cysts and oocysts are required for infection to occur (less than 100 cysts/oocysts).

Entamoeba histolytica:

  • developing countries that have poor sanitary conditions,
  • Incubation period usually 1 – 4 weeks,
  • symptoms include loose stools, abdominal pain and cramping,
  • severe form (amoebic dysentery) associated with abdominal pain, bloody stools, and fever,
  • in rare cases, parasite invades the liver and forms an abscess.

Dientamoeba fragilis:

  • protozoan parasite with a world-wide distribution,
  • does not have a protective cyst stage,
  • symptoms, if present, include diarrhea, abdominal pain and cramping, loss of appetite, weight loss, nausea and fatigue,
  • may result as coinfection with pinworm (Enterobius vermicularis).

Although enteric viral infections are responsible for only 5-10% of cases of traveler’s diarrhea, illness does occur and can be fairly debilitating. Nausea and vomiting are the most common symptoms associated with enteric viral infection. Norovirus and rotavirus are responsible for most cases of enteric viral infection.

Considering that 50,000,000 people travel to developing countries each year, and that 30-50% of travelers to high-risk areas become ill during a 1-2 week visit, approximately 50,000 cases of traveler’s diarrhea occur each day. If you are traveling to a high-risk country, take measures to protect yourself and your family from an illness that could not only destroy your vacation, but may also follow you home!

Develop Kids’ Creativity and Teach Biology: Potato Prints and Sea Shells, Ways to Create and Learn

One way to develop children’s artistic talent with lively biology lessons is to teach them how to make potato prints, dried flower pictures and sea shell gifts.

Creating works of art using natural materials like flowers, leaves and sea shells is an art lesson and a biology lesson wrapped in one. Depending on the children’s age and manual skills, one of these methods producing lovely pieces of art work will be suitable for them.

Potato Prints

Making potato prints is the easiest method and can be managed by children as young as five with the suitable help and supervision of an adult, particularly as the use of a sharp knife is involved. All that’s needed are a few fresh, good sized potatoes, a glass of water, a sharp knife, drawing paper and water colors or any other paint which dissolves in water.

First decide what you are going to make. Potato prints can be entire pictures which can be framed and hung for the proud young artist to display. Smaller formats can be turned into greeting cards and bigger sheets can even be used as personalized wrapping paper.

Next, decide on the design according to the object you wish to produce. Then cut the potato in half and again in even-sided wedges, which are to be used as print stamps. Formats can be square, round or half-moon shaped. Moisten the paint sufficiently and dip the potato stamp into the color, then print directly onto the paper. The result is a lovely, mosaic-like pattern.

Admittedly, there’s not much of a biology lesson here, but the kids’ creativity will be stimulated and they learn that natural materials can be put to different uses.

Gifts Decorated With Sea Shells

When by the ocean, take the children for a walk along the beach. They can learn about maritime life by collecting shells. Don’t let them gather broken, too dirty or too tiny shells if you wish to teach them how to decorate gifts by using sea shells. With a bit of help, this artistic activity is also suitable for younger children.

Clean the shells with the help of a steel brush and let them dry thoroughly. Select an item with a smooth surface, like a plain wooden box or an unpainted picture frame. Make sure the surface you wish to apply the shells to is very clean and dry. Turn the shells upside down and erase any irregularities of the rim with a metal or sandpaper file. Remove dust. Apply a thin layer of strong glue and press down firmly.

The shells can be used in their natural state or they can be covered with clear varnish or sprayed with gold or silver spray.

Dried Flower Pictures

Making works of art from dried flowers is a much longer process as the kids are supposed to produce the raw material themselves. Walks in the countryside or a visit to your own flower garden provide children with botanic lessons. For the ultimate purpose of making dried flower pictures it’s best to collect flowers and leaves which preserve well, such as maple leaves, oak leaves, poppy seed flowers, simple roses and pansies.

The drying process involves spreading out the collected flowers carefully so as not to damage the petals, placing them between two sheets of blotting paper and piling a few heavy books on top. Once the flowers and leaves are dry and pressed, they must be carefully removed with the help of pincers, arranged in the desired pattern and perhaps be cut to size and shape with sharp nail scissors.

Glue is applied to the surface, cardboard or silk being the most suitable, and pressed down firmly. Again, the finished art work is best preserved framed and under glass or else laminated.

Kids will be very proud to have created pieces of art, letting their fantasy and imagination guide them and, at the same time and with no effort, will have learned about botany and sea life.

Uncomplicated Gonorrhea: Cervicitis and Urethritis

Gonorrhea is a sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae.

Gonorrhea is transmitted through direct close contact between individuals, usually sexual. And infection can be passed from mother to infant during passage through the birth canal. However, because N. gonorrhoeae does not survive long outside the human host, and is susceptible to temperature extremes and drying, transmission does not occur through skin to skin contact, or through contact with contaminated objects. Thus, N. gonorrhoeae cannot be contracted through contact with a contaminated toilet seat or other surface.

Gonorrhea is the second most frequently reported communicable infection in North America, second only to chlamydia.

Most cases of gonorrhea are uncomplicated genital tract infections: cervicitis in women, and urethritis in men. Infection of the lower genital tract occurs through direct inoculation of columnar epithelial cells of mucous membranes in the cervix and the urethra. Infection of the vagina does not usually occur, except in prepubescent females, where infection may involve vaginal epithelial cells and the vulva (vulvovaginitis). Changes that occur in the vaginal mucosa at puberty protect vaginal epithelial cells from invasion. Neisseria gonorrhoeae and Chlamydia trachomatis prefer columnar epithelial cells in the cervix.

  1. gonorrhoeae may also infect columnar epithelial of other mucosal surfaces: conjunctiva, throat (oropharynx) and rectal mucosa.

Most infections occur in the under age-24 group, especially those with multiple sexual partners who engage in unprotected sexual intercourse. In 2016, 340,000 cases of gonorrhea were reported to the Centers for Disease Control and Prevention (CDC). However, it is estimated that only about half of all infections are reported suggesting that approximately 700,000 cases of gonorrhea occur each year in the U.S. alone.

Gonococcal infection (gonorrhea) can be asymptomatic, especially in women. Most women who are infected do not have noticeable symptoms. Symptoms generally present 5-7 days following exposure, but may present as early as 2 days or as late as 30 days following exposure.

Symptoms of gonorrhea in men with acute urethritis include:

  • white, yellow or green discharge (scant or copious; clear or purulent),
  • frequency of urination,
  • burning during urination.

Symptoms of gonorrhea in women with acute cervicitis/urethritis include:

  • vaginal discharge,
  • pain during urination,
  • inflammation of the cervix ,
  • irritation of the cervical os (opening),
  • vaginal bleeding between periods.

Screening of women at high risk for sexually transmitted infection (STI/STD) is an essential component of the control of gonorrhea. Because gonorrhea is often asymptomatic in women, all sexually active women at increased risk should be screened for gonorrhea.

Risk factors include:

  • previous sexually transmitted infection(s),
  • new sexual partner(s),
  • multiple sexual partners,
  • inconsistent condom use,
  • drug use,
  • commercial sex trade work.

Treatment for uncomplicated gonorrhea includes:

  • Ceftriaxone (125 mg single dose intramuscular injection)
  • Cefixime (400 mg oral single dose)
  • Ciprofloxacin (500 mg oral single dose)
  • Ofloxacin (400 mg oral single dose)
  • Levofloxacin (250 mg oral single dose)

Plus treatment for chlamydia, as appropriate.

Neisseria gonorrhea may also be involved in a number of other types of infections – conjunctivitis, oropharyngitis, rectal gonorrheae and other more complicated gonococcal infections.

Anthrax in Cattle: The Risk to Humans

There are 3 main types of anthrax – cutaneous, gastrointestinal and respiratory. All three types of infection can occur in animals and humans. Spores are an important factor in transmitting infection, and animals usually become infected through grazing in areas where large numbers of spores are present in the surface of the soil (link to anthrax and cattle). Therefore natural infection in humans is not likely to occur unless they are in contact with infected animals or animal products.

Infection in animals is usually gastrointestinal, and the most likely route of infection in grazing animals is through ingestion of spores during dry periods following flooding. Spores are brought to the surface during periods of heavy rainfall and remain there and become concentrated during dry spells. Ingestion alone does not necessarily result in infection – the spores require a lesion of some sort to gain entry into the tissues. Gastrointetinal lesions may occur when grazing on dry, spiky, gritty grass that grows close to the soil – infection occurs where spores have also been deposited on the soil.

Grazing animals may also become infected through inhalation of spore-laden dust (pulmonary anthrax), although infection by this route is much less common than through ingestion. Animals that feed on the carcasses of dead animals can also become infected during outbreaks in grazing animals.

Humans become infected through contact with infected animals or animal products such as carcasses, hides, wool, hair and bone meal. Therefore, in areas where infection in livestock is uncommon, human infection is also rare.

The World Health Organization (WHO) reports higher incidence of infection in certain areas of Canada such as the MacKenzie Bison Range, North West Territory and Wood Buffalo National Park in northern Alberta, with sporadic outbreaks occurring in southern Alberta and Saskatchewan. In the U.S., sporadic cases occur in South Dakota, Nebraska and Oklahoma, with more persistent outbreaks in western Texas. In other areas of the world outbreaks occur more consistently – Central and South America, Mexico, South Africa, Middle East, Soviet Union, southern India, and south-east Asian countries (Vietnam, Cambodia, western China, Thailand).

The most common form of natural human infection is cutaneous anthrax, accounting for at least 95% of cases world-wide. Cutaneous anthrax is readily treated with penicillin and a number of other antibiotics. Without treatment, 10-20% of cutaneous infections may be life-threatening. Contact with the vegetative form of the bacteria in the fluids and tissues of sick or dying animals, or with spores in dead carcasses, meats, hides, hair, wool or bone does not guarantee infection. Infection requires a skin lesion (cut, scrape, etc.) in order to gain entry to the tissues. In 2-3 days (may occur as early as 9 hours or as long after as 7 days) a pimple-like red elevated area appears, followed 1-2 days later by a ring of blister-like, watery fluid-filled vesicles with swelling in the surrounding area. By 5-7 days, an ulcer forms (eschar) (see photo). By approximately 10 days, the eschar begins to heal and may take up to 6 weeks to resolve. Treatment at this stage does not speed healing. Without treatment a small number of cases may develop systemic infection.

Gastrointestinal and pulmonary anthrax have much higher mortality rates than cutaneous anthrax, often because they are more likely to go unrecognized and untreated. Treatment in the early stages of either infection is very effective; however, the disease progresses rapidly, and in the latter stages of infection treatment is often ineffective.

Gastrointestinal infection may occur following ingestion of raw or improperly cooked meat from sick or dead animals and symptoms are similar to other food-borne illnesses –

nausea, vomiting, fever, abdominal pain. Cases may be mild or severe – in severe cases the mortality rate is approximately 50% even with treatment.

Pulmonary anthrax is even more likely to be misdiagnosed as the initial stage of infection involves flu-like symptoms – mild fever, fatigue and malaise lasting one to several days. Without treatment at this stage, infection progresses rapidly to difficulty breathing, disorientation, toxemia and death. Naturally acquired pulmonary anthrax in humans is extremely rare.