We’re in the middle of summer, and many of you probably enjoy taking advantage of the great outdoors at this time of year. And you’re not alone – ticks love this time of year too. They tend to emerge in the warmer weather, so between spring and fall is the peak time for occurrence of tick-transmitted diseases. So it’s important to be aware of the prevalence of tick-borne diseases in your area.

In the US and Europe, Lyme disease is the most common of these conditions, and represents an important public health concern. It was named after the town of Lyme in Connecticut, where a cluster of the first cases of the disease in this country were recognized in 1975. The disease itself is caused by the bite of a tick that is infected with the bacterium Borrelia burgdorferi. Most commonly in the US, the Ixodes species of deer tick is involved in transmitting the bacterium to people.

 

 

PREVENTIVE MEASURES

These ticks are especially prevalent in grassy and wooded areas, so it is important to take precautions when out and about:

 

Wear Appropriate Clothing

  • Light colors help you to recognize ticks more easily
  • Long sleeves protect the arms
  • Long pants protect the legs
  • Avoid wearing flip flops or open shoes
  • Tuck pants into socks or boots
  • Use Insect Repellent – apply to exposed areas of skin, and spray onto clothing too

 

Inspect for ticks

  • Check for attached ticks every few hours outside
  • Check again upon return home
  • Have a partner check difficult-to-see areas
  • Check pets too
  • Change clothes upon return home – shake out those you wore while outdoors

 

If You Find An Attached Tick

  • Remove immediately – use tweezers to grasp firmly near the head, and pull without squeezing
  • If mouthparts remain attached, remove using tweezers
  • Clean the area of skin affected, and apply antiseptic cream
  • If in doubt, save the tick in a small container (or between some pieces of sticky tape) in case it needs to be identified later

 

SYMPTOMS

Symptoms and signs of Lyme disease are variable because it can affect numerous body systems. Some of the more classic symptoms, however, include:

 

Early Symptoms

  • Skin rash: One of the hallmarks of the disease, affecting up to 80% of infected people, is erythema migrans. This is the classic rash that has a bull’s eye shape – a central dark red region and peripheral clear halo are surrounded by an outer red ring. It develops 3-30 days following a tick bite, and spreads with time. It should be differentiated from a rash that results after a tick bite due to an allergy to the tick’s saliva. This occurs within 72 hours of a bite, disappears with time, and is not indicative of Lyme disease.
  • Flu-like ailments: Fever, fatigue, aches, headache, and stiff neck are often reported early on in the course of disease.

 

Later Symptoms

If Lyme disease goes untreated, the bacterium can spread to other body systems. The joints and nervous system are a couple of the more common regions affected in such cases:

  • Joint pain: Untreated patients may sometimes develop joint pain, especially in the knees.
  • Neurological symptoms: Occasional patients can develop numbness or weakness of the limbs, facial paralysis, or even meningitis in severe cases.

 

It is important to remember, however, that not every tick is infected with Borrelia burgdorferi. Therefore not every tick bite leads to Lyme disease. If you do develop any concerning symptoms following a tick bite, however, seek medical advice as soon as possible – this will enable best treatment results in the event that you do have Lyme disease.

Don’t forget to check your dogs too – not only can they be bitten by ticks, but they too can develop Lyme disease. Ticks often go unrecognized on dogs due to their thick coats. So be sure to pay some extra attention to your dog after a walk, and groom him well to check for attached ticks.

And whilst the prospect of tick-borne disease shouldn’t keep you indoors all summer, it certainly pays to take preventive measures to guard against tick attachment, especially in regions where Lyme disease is prevalent.

 

 


 

 

 

 

 

 

 

 

 

 

 

 

A third of us are infected with Toxoplasma gondii, a parasite that can be transmitted to us by animals. Cats represent a major source of this organism, and are therefore a common route of infection for us since they continually shed the parasite. Consequently we can become infected with Toxoplasma gondii if we come into contact with anything that is contaminated with the organism as a result of a cat’s shedding. Some ways include:

  • Contaminated soil  (when gardening in an area where cats have defecated)
  • Cleaning the cat litter box
  • Contaminated water
  • Undercooked meat (lamb, pork, and venison especially – these animals are infected by cats in the same way as we are)
  • Cooking utensils coming into contact with undercooked, infected meats

Although many people are infected with this parasite, most are unaffected by it, and show no clinical symptoms since the immune system effectively prevents it from causing disease; however, clinical toxoplasmosis can be a real problem for people with weakened immune systems, such as:

  • HIV infected patients
  • Chemotherapy patients
  • Organ-transplant recipients

Additionally, it poses a particular risk for unborn babies. A  woman who comes into contact with the organism for the first time during her pregnancy may transmit it to the fetus in utero, resulting in birth defects or even infant fatalities. Transmission of the parasite to an unborn baby, however, is less likely if the woman has previously come into contact with the organism at least six months or more, prior to becoming pregnant.

Links With Brain Cancer?

Interestingly, a recent study reports a correlation between rates of infection of Toxoplasma gondii, and the incidence of brain cancer. Global data on brain cancer in people from 37 countries was collected and compared with the prevalence of Toxoplasma gondii infection in those regions. The research group reported that brain cancer rates increased in countries where the parasite was more prevalent.

This ecological study, however, merely points to a correlation between the two events – it does not imply that the parasite actually causes brain cancer in people. And certainly the opposite could be true – it’s not impossible that brain cancer could be the driving factor behind Toxoplasma gondii infection.

So as it stands, this report does not prove cause and association, but is predominantly hypothesis-generating, and does provoke scientific curiosity. In the words of one of the authors:“These were the best data available and we felt they were sufficient to take the first step. Working with actual brain cancer patients is an obvious next step, but it would be an expensive proposition.  It is a lot easier to justify the second, expensive step when you have some evidence for the hypothesis. We are hoping that our results motivate others in the field to do further studies.”

Thomas, Lafferty, Brodeur, Elguero, Gauthier-Clerc & Misse. 2011. Incidence of adult brain cancers is higher in countries where the protozoan parasite Toxoplasma gondii is common. Biology Letters

 

By now you’ve likely heard something about the outbreak of food-borne illness due to E. coli that is currently causing problems in Germany. This outbreak, reportedly the world’s largest due to E. coli, has so far killed 15 people and left more than 1000 others ill.

Although the exact source of the virulent strain of this bacterium remains unknown, the pathogen has been identified on cucumbers imported from Spain. Specifically it has been identified as Shiga toxin-producing E. coli (STEC) which causes Hemolytic Uremic Syndrome (HUS).

Vegetables, however, don’t have colons for colonization with this bacterium, so how did they become “infected”?

            

STEC and HUS

Most research on the epidemiology of STEC in animals has involved E. coli 0157:H7, and cattle are considered the major reservoir of the STEC that result in human infection. This strain is so widely distributed among cattle that it may likely be present periodically on most farms at some stage. Although this pathogen can only survive transiently in soil when shed by affected cattle, it is, however, capable of prolonged persistence in manure and environmental waters.

Consequently, polluted groundwaters may have been the source of the bacterium in this outbreak, and the vegetables were merely vectors of disease. That is, they provided a mechanical means of transporting the STEC into people.

HUS typically begins with an episode of bloody diarrhea following infection of the gastrointestinal tract with E.coli 0157:H7. This pathogen produces toxins that destroy red blood cells and cause kidney damage, resulting in a combination of hemolytic anemia, thrombocytopenia and acute renal failure. HUS therefore represents a medical emergency, and although the majority of patients recover from illness, mortality rate can be up to 10%, with children and the elderley being particularly at risk.

Growing Tension

Sadly this recent STEC/HUS outbreak has additionally spread to other northern European countries, and the situation is expected to further worsen in the coming week. Subsequently, diplomatic tension between Germany and countries such as Spain, France and Russia, is rising, as some countries have banned vegetable imports from Germany and Spain.

The German public has now been warned to avoid eating raw vegetables, such as lettuce, tomatoes and cucumbers, and some products have even been removed from store shelves.