Tag Archives: infectious disease

Climate change brings more infectious diseases. Many people are completely unaware of this

Infectious diseases are transmitted through water, food, or vectors such as mosquitoes are highly sensitive to the weather. Climate change is affecting the weather, making it easier to transmit diseases such as malaria or yellow fever over larger areas.

But according to a new global survey, many are unaware of this.

Image credit: Flickr / Shona Na

The link between climate change and infectious diseases has long been established through scientific research. The Lancet Countdown, for example, found climate suitability for disease transmission has already increased. Another recent study found that both pathogens and disease transmission are affected by climate change, and the WHO already has a guide on this. However, this seems to be news to many.

Students from the international master’s degree Erasmus Mundus on infectious diseases (IDOH+) carried out a survey among 458 people and found that almost half weren’t aware of the link between climate change and infectious diseases. Most of those surveyed were either European or Asian.

The study showed that participants with a background in natural sciences had a greater knowledge about infectious diseases and understood that infectious diseases are sensitive to climate change. Their average scores in the survey were significantly higher than participants with other backgrounds.

Almost half of those surveyed (48.9%) had never before considered the effects of climate change on infectious diseases. But this percentage drop to 38.4% among those with a solid knowledge of the natural sciences, and then rises to 59.2% in those who work in sectors not related to natural sciences.

Up to 64.6% of the participants were afraid of contracting an infectious disease. Those in Europe were less afraid (51.7%) than their US (71.4%) and Asian (87.7%) counterparts. Regarding protection measures, the large majority (70.5%) consult the need for vaccines before traveling to a tropical country.

In line with this, over half of those surveyed (56.1%) were afraid of contracting an infectious disease in a tropical country, although differences were detected according to nationality: in this case, European participants were more afraid (72.0%), when compared to US (41.3%) and Asian participants (37.7%).

Western nationalities tended to have a higher knowledge of climate change and infectious diseases than oriental nationalities, but not on the link between climate change and infectious diseases, the study showed. This might be explained by geographical and cultural characteristics, the researchers argued.

They found there are more awareness campaigns on climate change and sustainability in Western countries whereas infectious diseases such as water and mosquito-borne diseases are more commonly seen in Asian countries. This shows the importance of educational training and public awareness interventions.

Max van Wijk, one of the authors of the study, said in a statement: “This data can help to establish intervention measures that can raise awareness among the public on issues related to climate change and infectious diseases. The study was done with an academic objective but has original content that can be applied to other studies.”

The researchers highlighted a set of limitations. The use of convenience sampling could have imposed a selection bias. Fluency in English of participants wasn’t accessed, which might have also imposed bias on their understanding. This limitation might have led to the underrepresentation of a part of the population in certain regions. Most significantly, perhaps, it’s a small sample size.

The pandemic might have influenced the knowledge, attitude, and perception of the participants since the study was conducted in late March, which was the initial phase of the pandemic. Occupation data of the participants weren’t collected in the survey, which the researchers believe would have been an interesting factor to integrate.

The study was published in the journal PLOS ONE.

Researchers document how asymptomatic COVID-19 cases unknowingly spread the coronavirus

study published mid-April reported that people infected with SARS-CoV-2, the coronavirus causing COVID-19, might be most contagious during the period before they have symptoms. Two studies published in late May showed that a high percentage of people with COVID-19 could be without symptoms.

In one study, Australian researchers reported that 104 of 128 people (81 percent) on a cruise ship who tested positive for the novel coronavirus were asymptomatic. In another study, researchers in Wuhan, China reported that 33 of 78 people (42 percent) who tested positive for COVID-19 were without symptoms.

Most recently, a multicenter study published in Travel Medicine and Infectious Disease shows that 60% of asymptomatic (symptom-free) COVID-19 patients in Sichuan province, China, were diagnosed as having pneumonia on their first computed tomography (CT) scan.

The study involved 100 asymptomatic and 411 symptomatic coronavirus patients in hospitals in 21 cities and 47 counties or districts from Jan 25 to Feb 20. The investigators also found that patients without symptoms were younger and came from higher-altitude areas with less resident mobility and more defined epidemiologic history than patients with symptoms but had similar rates of underlying conditions.

Of the 100 well-documented asymptomatic cases, 17 (27.4%) later developed symptoms, two of the older patients developed severe symptoms during hospitalization. No asymptomatic patients died. One patient was believed to have transmitted the virus during the incubation period.

In a May 30 letter to the editor published in Influenza and Other Respiratory Viruses, public health experts describe a likely asymptomatic COVID-19 spread in a household and school after travelers returned to Brunei after attending a religious event in Malaysia from Feb 28 to Mar 2.

Of the more than 4,000 confirmed cases linked to the event, 19 from Brunei tested positive for COVID-19 and infected 52 others. According to the researchers, this is the first report documenting the role of asymptomatic SARS‐CoV‐2 transmission in the propagation of a large superspreading event.

The authors said that their findings support the use of testing and longitudinal surveillance of asymptomatic close contacts, as well as widespread testing at mass gatherings in places with known community spread.

US Centers for Disease Control and Prevention | Your cloth face covering may protect them. Their cloth face covering may protect you.

All these studies strengthen the argument for people to wear masks. After first telling the public there was no need for people to wear a mask unless they were sick or coughing, the US CDC revised their position. Since early April, the agency has recommended that in addition to physical distancing measures, people should wear a face covering if they go to a public place in settings where physical distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission. They have posted instructions on how to properly wear a cloth mask.


How good hand-washing beats COVID-19 (and other contagious diseases)

Image via MSU Today.

The most important piece of advice we need to follow to help us stay safe from COVID-19 is this one: wash your hands.

SARS-CoV-2, the virus causing COVID-19, and other respiratory viruses spreads easily by droplets from breathing, coughing and sneezing. Because our hands touch many surfaces, they can pick up microbes, including viruses. Then by touching contaminated hands to your eyes, nose, or mouth, the pathogens can infect the body.

Coronaviruses, like this year’s novel coronavirus called SARS-CoV-2 that has infected over 110,000 worldwide are encased in a lipid envelope — basically, a layer of fat. Soap can break that fat apart and make the virus unable to infect you.

There are two ways to decrease the number of microbes on your hands.


First strategy: decrease the overall biomass of microbes – that is, decrease the amount of bacteria, viruses and other types of microorganisms. We do this by washing out hands with soap and rinsing with water. When you wash your hands with soap and water, the soap chemically works to break down the oil, while the friction from rubbing does it mechanically. The more soap and the longer the hands are rubbed together, once rinsed away with water, the less oil and microbes are left on your hands. Public health experts agree that this method of hand washing, for at least 20 or more seconds at a time,

From the European Centre for Disease Prevention and Control (ECDC)

Second strategy: kill the microbes. We do this by using products with an antibacterial agent such as alcohols, chlorine, peroxides, chlorhexidine or triclosan. However, the efficacy on these agents can vary depending on the concentration of the antibacterial agent and on the particular microbe.

What about bar soap? Numerous studies have found that bacteria can stay on bar soap that stays wet because it gets used frequently. But studies that have shown that bacteria don’t seem to transfer to the next user. If the bar of soap looks slimy, rinse it off under water before you lather your hands, and try to store it so it will dry out between uses.

What if there’s no soap? If you’re in a public bathroom, and there’s no soap, just rubbing your hands together under the water does do some good. A 2011 study from researchers at the London School of Tropical Hygiene found that washing with water alone reduced bacteria on hands to about one-quarter of their prewash state. Washing with soap and water brought bacterial counts down to about 8% of where they were before washing.

What if there’s no soap or water? You can use hand sanitizers. Lipid membrane viruses like coronaviruses are killed by alcohol-based hand sanitizer as long as it is at least 62% alcohol. Make sure to use enough so that it covers all the surfaces on your hands. Rub that on until your hands feel dry, which should take about 20 seconds. Alcohol kills some bacteria and viruses by breaking down their protective membranes, which basically makes them fall apart. But it doesn’t work for all germs, such as norovirus, Clostridium difficile, which can cause life-threatening diarrhea, or Cryptosporidium, a parasite that causes a diarrheal disease called cryptosporidiosis. But it works very well for enveloped viruses such as Hepatitis B virus, influenza virus, and coronaviruses!

What about drying hands with paper towels? Paper towels have a beneficial effect beyond simply washing. Rubbing your hands with a paper towel removes even more germs than washing alone. Dry hands are also less likely to spread contamination than wet hands.

How often do you need to wash? A lot. The CDC says to wash your hands:

  • Before, during, and after preparing food;
  • Before eating;
  • Before and after taking care of someone sick;
  • Before and after treating a cut or other wound;
  • After going to the bathroom;
  • After changing diapers or helping a child in the bathroom;
  • After blowing your nose, coughing, or sneezing;
  • After touching an animal, or touching pet food or pet waste;
  • After handling pet food or pet treats;
  • After touching garbage.

With all the messaging in the news, on social media, and elsewhere about COVID-19 you’re probably doing a lot more hand washing than you’re used to. But regular and proper handwashing should be done all the time and not just during outbreaks.

And remember after washing, try to keep your hands clean. Avoid touching contaminated surfaces. Use a clean paper towel to open bathroom doors. Disinfect dirty surfaces that you use every day, like the touchscreen on your phone and your computer keyboard.

Progress in meningitis lags behind other preventable diseases

The global disease burden of meningitis remains unacceptably high, and progress lags behind that of other vaccine-preventable diseases, according to a new analysis published in The Lancet Neurology. Increased awareness of the disease, wider protection and improved diagnosis and treatment needed to control cases of meningitis.

The Institute for Health Metrics and Evaluation (IHME) Global Burden of Disease study showed that deaths from meningitis were reduced by 21% globally between 1990—2016, while other vaccine-preventable diseases saw more significant declines: measles (93.0%), (tetanus) 90.7%, and diarrhea due to rotavirus (57.9%). The number of actual cases of meningitis increased during that time period, from 2.5 million in 1990 to 2.82 million in 2016, due to increased population size.

Haemophilus influenzae type b was the most common cause of incident meningitis in 1990, at 780,070 cases globally, but decreased the most (–49.1%) to become the least common cause in 2016, with 397,297 cases. Meningococcus was the leading cause of meningitis mortality in 1990 (192 833 deaths globally), whereas other meningitis was the leading cause for both deaths (136,423) and incident cases (1.25 million) in 2016. Pneumococcus caused the largest number of years of life lived with disability (YLDs) (634,458) in 2016, because of its more severe long-term effects on survivors.

The highest concentration of cases and deaths from meningitis was found in the sub-Saharan African countries that are collectively known as the “meningitis belt”. This is despite huge progress in reducing meningococcal group A disease by 99% in the meningitis belt through the MenAfriVac vaccination programme. This region is not only prone to meningitis but also very prone to epidemics such as malaria. The “belt”, with an estimated 300 million people in its total area, consists of the Gambia and Senegal in the west to Ethiopia and Eritrea in the east.

IHME’s Professor Nicholas J. Kassebaum, commented, “Declines in the incidence and mortality of meningitis have lagged far behind those of other vaccine-preventable diseases, such as diarrhea and lower respiratory infections. It is likely that the growing number of meningitis survivors with lifelong disabilities are living in communities without the resources or programs to support them.”

Linda Glennie from the Meningitis Research Foundation said, “This research shows that a huge number of people are still being affected by this dreadful disease. Vaccination is the only way to prevent meningitis and despite major progress over the last 20 years, large epidemics have occurred recently showing again that meningitis is very far from being defeated.”

Bacterial meningitis is a deadly disease that strikes without warning and can leave survivors with lifelong after effects as serious as deafness, blindness and brain damage. Meningitis burden remains high and progress lags substantially behind that of other vaccine-preventable diseases. More effort should be given to developing vaccines with broader coverage against the causes of meningitis and making these vaccines affordable in the most affected countries to improve vaccine uptake. There is also a need to improve access to low-cost diagnostics and therapeutics, and create a better support infrastructure for disabled survivors. Ongoing surveillance of the specific types of bacteria causing meningitis is also crucial to monitor meningitis burdens and trends worldwide.

Learn more about bacterial meningitis from this introduction course by the World Health Organization (WHO).

A team of researchers from the European Antimicrobial Resistance Surveillance Network (EARS-Net) estimates that over 33,000 people die each year from antibiotic-resistant infections in Europe. They noted that the increasing burden of these infections is similar to that of tuberculosis, HIV, and influenza combined.

The study published in The Lancet Infectious Diseases looked into the incidence of five types of infections caused by antibiotic-resistant bacteria in 31 European Union/European Economic Activity (EU/EEA) countries and calculated the impact using the number of cases, attributable deaths, and overall health burden. This study is the first to estimate the burden of all types of infections with antibiotic-resistant bacteria and express it in DALYs.

The authors say the findings clearly show the health impact of antibiotic resistance in Europe and emphasizes the need for collaboration and coordination of EU/EEA countries to address the increasing public health problem of antibiotic resistance.

The study focused on eight species of bacteria frequently isolated from blood or cerebrospinal fluid (CSF) using EARS-Net data collected from 2015 from each of the 31 EU/EEA countries. The five types of infections were bloodstream infections (BSIs), urinary tract infections (UTIs), respiratory tract infections (RTIs), surgical site infections (SSIs), and other infections. The pathogens studied were colistin-resistant, carbapenem-resistant, or third-generation cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus faecalis and Enterococcus faecium.

Here are some of the 10 most dangerous antibiotic-resistant pathogens globally


The annual number of cases and incidence rate, the number of attributable deaths and attributable mortality rate, and the number and rate of disability-adjusted life-years (DALYs) were calculated using computational models. DALYs are particularly important because it gives an indication of the overall burden of disease. The researchers estimated that 671,689 infections were caused by the selected antibiotic-resistant bacteria in the EU/EEA countries in 2015, with 33,110 attributable deaths and 874,541 total DALYs. These corresponded to an incidence rate of 131 infections per 100,000 population, an attributable mortality rate of 6.44 deaths per 100,000 population, and 170 DALYs per 100,000 population. As a comparison, tuberculosis, HIV, and influenza altogether account for 183 DALYs per 100,000 population. As expected, the burden of antibiotic-resistant infections was highest among children under the age of 1 and adults over the age of 65.

Four drug-resistant bacteria had the largest impact, accounting for 67.9% of the DALYs per 100,000 population. This includes third-generation cephalosporin-resistant E coli, MRSA, carbapenem-resistant Pseudomonas aeruginosa, and third-generation cephalosporin-resistant K pneumoniae. Almost two-thirds of the infections (426,277, 63.5%) were associated with healthcare and accounted for 72.4% of attributable deaths and 74.9% of DALYs. The study also showed that the burden of antibiotic-resistant bacteria is focused on countries in southern and eastern Europe, where antibiotic consumption tends to be higher. Italy and Greece were the most affected countries, accounting for a combined 21.3% of total DALYs. When the team applied the same method to EARS-Net data from 2007, they found that the number of deaths attributable to antibiotic-resistant bacteria had more than doubled, from 11,144 in 2007 to 27,249 in 2015.

The US Centers for Disease Control and Prevention (CDC) published a report in 2013 that used 2011 surveillance to provide estimates of the burden of antibiotic resistance in the United States. That report showed that antibiotic-resistant infections affected over 2 million people a year, with 23,000 attributable deaths. The current EARS-Net incidence of antibiotic-resistant infections is 2.6 times higher than the CDC study with the attributable mortality 1.22 times higher.

A related commentary by Dr. Evelina Tacconelli and Dr. Maria Pezzani of the University of Verona strongly emphasized the urgent need for greater political commitment and dedicated resources for combating drug-resistant infections. They suggested approaches including a definition of a Europe-wide standard for antibiotic usage in hospitals and the community. They also proposed the establishment of a rate of resistance for specific antibiotics whereby countries would have to take urgent action, the creation of a minimum gold standard for infection control measures, and identification of annual targets for each country’s national antimicrobial resistance plans.

Transplant Organizations issue a guidance statement regarding Zika virus

The Zika virus has been in the headlines lately for its apparent association of microcephaly in the children of mothers infected when they were pregnant. While there is a strong correlation, a true causation has not been completely verified, and is still being investigated.  In most people the virus causes only very mild illness that resolves on its own (such as fever, rash, muscle aches, and headache), and in many individuals is completely asymptomatic. Occasionally, its effects can be more severe, such as leading to reported cases of Guillain-Barre syndrome (a severe neuromuscular illness causing paralysis). It is still not known exactly why some people may develop severe complications while the majority do not. Zika virus has been covered previously on the ZME website.

It is also known that while the Zika virus typically spreads by an insect vector (the mosquito Aedes aegypti in most cases), it is now thought to also spread by sexual contact. It is uncertain if transmission could occur thorough organ donation, but if virus is present in the blood or other body fluids, then this mode of transmission would be possible in principle. Due to concern that this unusual mode of transmission could affect a vulnerable population, the Organ Procurement and Transplantation Network (OPTN) and United Network for Organ Sharing (UNOS) has set up an Ad Hoc Disease Transmission Advisory Committee (DTAC) to provide information and recommendations to transplant physicians, and this month came out with the first guidelines. As a transplant physician myself ( I’m a pediatric nephrologist, caring for children with End-Stage Kidney Disease who will need or have received a kidney transplant), I recognize the need to be certain that our supply of donor organs are safe for our patients, and to be able to advise our current transplant patients about travel to areas where Zika is known to be endemic.

Organ transplant recipients (such as heart, liver, kidney, lung, etc) represent a vulnerable population. In order to prevent rejection of the donor organ, the patient must be immunosuppressed with medications, making it difficult to fight off infections that most of us wouldn’t be very bothered by. It is completely unknown, at the present time, how Zika virus would affect an immunosuppressed individual. It’s affects could remain mild, as it is in most people with a normal immune system, or it could have serious unforeseen consequences.

The DTAC advises caution for people who have already received a transplant, or those who are on the transplant list, if they will be traveling to a Zika endemic area. Those areas would include Mexico, Central America, and South America. They also recommend that when a donor is being considered (and that could include either a living donor or deceased donor), that the transplant center should take into account the donor’s recent travel history, and if they had recent symptoms of viral infection. Again, many people (around 20%) will not have any symptoms at all, making symptomatology an unreliable marker of infection. The committee does not feel that even these factors should result in absolute exclusion of that organ being used, but should be decided on an individual basis for each patient. Some patients may be in more urgent need of an organ, and may not survive if they have to wait too much longer for the next matching organ to come up. In other cases, a person may have already been on the transplant list for a very long time due to having built up a lot of antibodies to other potential donors, and may not get another matching offer for years.  It may be a decision that the patient, their family, and their transplant physicians need to make together if the organ in question is felt to be at a higher than average risk for Zika virus.

Unfortunately, routine screening methods are not yet available for use by clinical laboratories. Screening can be achieved by the CDC in suspected cases of Zika related illness, and therefore it is not yet recommended or possible for organ donor’s to be screened for Zika virus as part of a donor evaluation. With time we will likely have a better understanding of the risk that Zika poses to individuals immunosuppressed for organ transplant. We will also likely have better screening methods that will be more readily available. For now, I think it is prudent to take precautions until more is known, but feel that there is no reason to panic, since there is no evidence at this time that donor organs have been compromised in any way.


References and further reading:

“Guidances for organ donation and transplantation professionals regarding the Zika virus”.  Feb. 4 2016.  UNOS Newsroom.


Interim Guidelines for Pregnant Women During a Zika virus outbreak – United States 2016.  CDC Morbidity and Mortality Weekly Report.  Jan. 22. 2016.


Possible Association Between Zika virus infection and Microcephaly – Brazil 2015.  CDC Morbidity and Mortality Weekly Report.  Jan. 29, 2016.