There are indeed varying definitions of a pandemic; some emphasize (or even require) human-to-human transmission and some don't.
It's difficult to apply a definition that emphasizes that human-to-human aspect to a vector-borne disease like Lyme disease. The WHO in particular has a more detailed, technical definition of an influenza pandemic, which is fairly easily applicable with minor changes to something like Covid-19, but would require more substantial modifications for it to apply to anything vector-borne. The WHO never uses the p-word even when discussing statistics of vector-borne disease that affect a lot of people worldwide (malaria, dengue etc.) Some researchers do use the pandemic (or epidemic) term(s) more loosely, and so one can find research papers referring to such widely spread vector-borne disease as pandemics. (The WHO has another related concept of a PHEIC [Public Health Emergency of International Concern], which they did apply for the first [and insofar only] time to a vector-borne disease--namely to Zika--in 2016.)
As far as Lyme disease and national authrorities are concerned (which may declare an epidemic--in somewhat more techincal terms this requires a departure from an expected level of occurence, thus it is a matter of some judgement to declare one): Lyme disease has had a somewhat controversial status in the US recently, with e.g. the CDC apparently avoiding to speak of an epidemic but an HHS task force on Lyme referring to it in such epidemic terms (in a report to Congress). The technical issue here seems to be which interval to consider, e.g. there's more of an increase if one compares 2016 to 2001, but data over a shorter time span e.g. 2008-2015 is relatively flat. Although Canada has seen a sharper upward trend (probably due to climate change), Canadian authorities apparently have been more reluctant to speak of an epidemic, instead talking of an "outbreak" or "emerging disease". There's some data from the ECDC showing an upward trend in Europe (and despite this, the ECDC doesn't seem to speak of an epidemic [in Europe] either), but I couldn't really find out which countries were responsible for most of this increase. In Germany, an increase was noted due to a change in reporting standards in some German states (Länder), but it's unclear how much of this kind of technicality explains EU-level data. (There's seemingly not a common standard of diagnosis or reporting in the EU for Lyme disease.)
Basically no, because the fairly standard definition of a pandemic requires human-to-human transmission
pandemic: An epidemic occurring over a very wide area, crossing international boundaries,
and usually affecting a large number of people. Only some pandemics cause severe
disease in some individuals or at a population level. Characteristics of an infectious
agent influencing the causation of a pandemic include: the agent must be able to infect
humans, to cause disease in humans, and to spread easily from human to human
Quoted from A dictionary of epidemiology, 6th ed. (2014), Miquel Porta (ed.).
The only human-to-human transmission of lyme disease mentioned in Wikipedia is across the placenta (i.e. in pregnancy).
Note that malaria is even more broadly spread (than lyme disease).
Now some scientists use the p-term much more loosely, e.g. a presentation by some Australian researchers calls Zika, Dengue, Japanese encephalitis, and scrub typhus "Pandemic Vector-Borne Diseases". Similarly a French & Canadian authors' paper on Zika calls it a pandemic. But this is a pretty non-standard usage of the p-word. I'm not sure how exactly to prove this last statement, but e.g. the WHO did not declare any of these to be pandemics.
The WHO has a consolidated page on vector-borne diseases (which mentions all of the above) and with stats like
Malaria is a parasitic infection transmitted by Anopheline mosquitoes. It causes an estimated 219 million cases globally, and results in more than 400,000 deaths every year. Most of the deaths occur in children under the age of 5 years.
Dengue is the most prevalent viral infection transmitted by Aedes mosquitoes. More than 3.9 billion people in over 129 countries are at risk of contracting dengue, with an estimated 96 million symptomatic cases and an estimated 40,000 deaths every year.
Despite these stats, they never call them pandemics or even epidemics, on that page, only "outbreaks". (You can argue this wrong, but that's how the pandemic terminology is [not] used, at least by the WHO.)
Outside of the disease that are even caused by infectious agents, there are papers that call obesity a pandemic. The WHO only seems to go as far as calling it an epidemic, but acknowledges its global scale as "an escalating global epidemic of overweight and obesity – “globesity”". (If you google that last term, it has more usage outside of the WHO.)
The CDC (in their Principles of Epidemiology in Public Health Practice, 2012) however seems to give a less restrictive/qualified def, i.e. only that a:
Pandemic refers to an epidemic that has spread over several
countries or continents, usually affecting a large number of people.
But they don't seem to talk of pandemics much; that book only mentions as an example "a pandemic of influenza". After defining an epidemic (in the usual way) "refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area", and discussing it in terms of infections, they also say that
The previous description of epidemics presumes only infectious
agents, but non-infectious diseases such as diabetes and obesity
exist in epidemic proportion in the U.S.
But with respect to vector-borne disease, they say e.g.
For example, an outbreak of malaria in the United States in 2006 would be an immediate threat, but malaria in Africa is a chronic problem.
The latter issue also applies to lyme disease in the northern hemisphere, i.e. to call even an epidemic, it would have be above "expected" levels.
On this angle, a 2017 NPR article which seems to stick fairly closely to the CDC definitions, notes
Epidemic: A sudden increase in the number of cases of a disease in a particular geographic area, beyond the number health officials typically expect. An increase that occurs in a relatively small geographic area or among a small group of people may be called an "outbreak."
For example, the Centers for Disease Control and Prevention calls HIV/AIDS, which affects 1.2 million people in the United States, an "epidemic." By contrast, the CDC called two cases of sickness from drinking raw milk (listeriosis) in the United States an "outbreak."
Pandemic: An epidemic spanning many countries and/or several continents. The difference between an outbreak, an epidemic and a pandemic can be murky and depends on the opinions of scientists and health officials.
The NPR page gives no examples of pandemics.
For some more examples of murkiness perhaps, although the WHO declared Zika a PHEIC (in 2015-2016), the CDC doesn't call it a pandemic in a long paper discussing it, although it does mention the PHEIC declaration. Likewise the ECDC only called it an "outbreak" even in pages that discussed the WHO's PHEIC declaration.
Following the 2009 H1N1 pandemic, the WHO was also criticized for not having a clear definition of a pandemic, although they do define "phases" of a pandemic in terms of geographic spread. Criticism included the fact that that phase approach did/does not take into account disease severity.
The ECDC also has a page delving on the issue (some of the critics of the WHO in the aforementioned regard were from the ECDC)
The internationally accepted definition of a pandemic as it appears in the Dictionary of Epidemiology is straightforward and well-known: 'an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people'.
It should be noted that this definition can apply to other infections subject to such global spread, e.g. cholera and HIV. There is no element of severity in it: while some pandemics are severe in the disease they cause in some individuals or at a population level, not all pandemics are severe.
WHO developed a more technical set of requirements for a pandemic:
The emergence of influenza A virus significant[ly] different genetically from circulating human influenza A viruses (i.e. many of the population are non-immune to the new virus) with the following three characteristics:
- Able to infect humans,
- Able to cause disease in humans,
- Able to spread from human to human quite easily.
|No animal influenza virus circulating among animals has been reported to cause infection in humans.
|An animal influenza virus circulating in domesticated or wild animals is known to have caused infection in humans and is therefore considered a specific potential pandemic threat.
|An animal or human-animal influenza reassortant virus has caused sporadic cases or small clusters of disease in people, but has not resulted in human-to-human transmission sufficient to sustain community-level outbreaks.
|Human-to-human transmission of an animal or human-animal influenza reassortant virus able to sustain community-level outbreaks has been verified.
|The same identified virus has caused sustained community level outbreaks in two or more countries in one WHO region.
|In addition to the criteria defined in Phase 5, the same virus has caused sustained community level outbreaks in at least one other country in another WHO region.
|Levels of pandemic influenza in most countries with adequate surveillance have dropped below peak levels.
|Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with adequate surveillance.
As you can see this WHO def they quote is pretty specialized to influenza and not easy to translate to a vector-borne disease, although it is fairly easy to apply it to a zoonotic agent (i.e. that has jumped species) other than influenza, as long as it gets to human-to-human transmission (phase 4 and above.)
The Zika outbreak of 2015-2016 is the only time the WHO declared a PHEIC over a vector-borne disease. (cf. Wikipedia) Also, in regard to Covid-19, the WHO declared it a PHEIC on Jan 30, and a pandemic on March 11, so the bar for the latter is higher.
Now if you want a purely declarative pronouncement... I did find one 1989 paper titled "Lyme disease. The hidden pandemic", but like with everything else vector-borne, you'll be hard pressed to find even national-level authorities that agree to even call it an epidemic in their own county.
Most countries don't even conduct very systematic surveys on lyme disease; the US seems to be the exception, but even there the numbers reported to the CDC (see table 2) appear to have been relatively stable over a decade (2005-2015), but the CDC also says that those numbers are probably underreported by an order of magnitude. On the other hand, you can find (more) papers calling it an epidemic in the US, albeit the CDC itself seems not to call it that in a 2017 survey of the 2008-2015 data. There is however a 2018 HHS report to Congress that says that "Tick-borne infections are an emerging public health epidemic in the United States". This documents points to a doubling of the number of cases in the north-east ("Upper Midwest, Northeast, and
Mid-Atlantic States") from 2001 to 2016 and a tripling of the number of counties "considered to be of high incidence for Lyme disease" (presumably in the same time frame, although that's not terribly clear). Back in the early 1990s, when surveillance efforts were being ramped up in the US, more cases were being discovered each year sometimes at an accelerated pace e.g. in NY state "the number of reported cases has increased fourfold in the 4-year period from 1986 through 1989" and (so) one can find articles in prestigious journals that spoke of an epidemic. Even for more recent data, given the substantial uncertainty in estimating the true number of cases... there's room for interpretation. I mean compare the CDC graph with HHS one:
Climate change is expected to make lyme disease more prevalent in Canada (as it already happened in the north of New England and Maine), actually the official statistics in Canada show a clear upward trend already, but even in Canada the autorities (PHAC) don't seem to speak of an epidemic, but they call it an "emerging disease" in Canada. There is a different Canadian authority (NCCID) that does refer to the trend in their country as an "outbreak", though.
The ECDC has page on vector-borne diseases which talks of some epidemics (and outbreaks) of West Nile fever and outbreaks of chikungunya, but they only use the latter term (outbreak) when talking of tick-borne diseases and that with respect to Crimean-Congo hemorrhagic fever, which is also caused by a (different) virus carried by some ticks. About lyme disease they only say it is the most common tick-borne disease (in Europe) "with at least 85 000 cases yearly, and has an increasing incidence in several European countries such as Finland, Germany, Russia, Scotland, Slovenia and Sweden". And then they discuss how climate change may affect its spread. There's a longer 2006 report to the WHO on lyme disease in Europe. Some of the graphs there show annual variation but not a clear trend for the period considered, even in some Baltic countries e.g.
The ECDC however has a more up-to-date graph (in a 2014 publication) for lyme disease across Europe showing an upward trend, although they don't seem to detail which countries are responsible for the increase.
It's possible that some of this trend is due to a change in reporting standards, if Germany is any indication:
Number of notified LB [lyme disease] cases by year of notification and states grouped according to year of implementation or change in LB surveillance. Data from 2007 to 2012 was included to allow comparison. The following changes were made in the implementation: In 2009 LA [Lyme arthritis] was included as notifiable manifestation of LB in all notifying states, in 2011 notification was introduced in RP (July) and SL (August), in 2013 notification was introduced in BY (data included since 1st of April 2013) and extended in BE (data included in Figure 1 since 1st January 2013). *Thuringia (TH), Saxony (SN), Saxony-Anhalt (ST), Brandenburg (BB), Mecklenburg-Western Pomerania (MV), Rhineland-Palatinate (RP), Saarland (SL), Bavaria (BY), Berlin (BE).
Numbers from France in roughly the same time frame don't show any appreciable increase, although they are limited to hospitalizations.
There as has also been a 2018 call for the EU to regulate the reporting standards for Lyme disease.
I could not find an explicit discussion in this regard, but my guess is that because the incidence changes observed for lyme disease have been relatively slow over time (and there are some methodological issues as well) makes authorities reluctant to speak of an epidemic.