Educational Review
Malaria from Ticks – Babesiosis
Paul-Erik Uggeldahl
Suvikatu 8, FIN-80200 Joensuu, Finland. E-mail: pe. uggeldahl @ gmail. com
In Europe the hard tick Ixodes ricinus is the vector of 5 human diseases: tick-borne encephalitis( TBE), Lyme borreliosis, tularaemia, anaplasmosis, and babesiosis. The tick can transmit the microbes of these diseases to humans when sucking blood.
The rarest of these diseases is babesiosis, which exists in Finland( 1). Symptoms of babesiosis can be similar to those of granulocytic anaplasmosis. First and foremost, however, it should be noted that babesiosis can mimic malaria. This is unsurprising, since, as in malaria, the vector is a protozoan, an intraerythrocytic parasite.
Babesiosis is a great infector of cattle, although lambs and dogs can also be infected. Vets are often familiar with this disease( 2). However, from contacts in Finland, my experience of their know-how has proved disappointing. This lack of knowledge also applies to ehrlichiosis and borreliosis, and their vectors, the ticks, which globally seems to be the Achilles heel for many.
Skin symptoms are absent in babesiosis. If skin symptoms occur, they may have been caused by the treatment, that is similar to that in malaria. Rashes are also rare in human anaplasmosis( HGA), while they dominate in borreliosis. Authors from New England in north-eastern USA( 3) report that babesiosis should be considered in all patients who have an inexplicable feverish disease and have lived in or travelled to an area where the disease is endemic. The disease must also be kept in mind when examining people who have received a blood transfusion within the past 6 months. Transfusion-transmitted babesiosis( TTB) is a major problem, which has not been sufficiently investigated in Europe( 4).
History of babesiosis
In 1888 Victor Babes, a Hungarian pathologist and microbiologist, observed intraerythrocytic microorganisms in feverish cattle with bloody urine( 5). Five years later Smith & Kilborne from the USA( 6) observed that ticks were vectors of Babesia bigemina in Texan cattle. Thus, for the first time, it was demonstrated that an arthropod( tick) could contract a microbe to a vertebrate host. However, Babes’ idea of bacteria was not correct( 5).
The first case of human babesiosis was reported half a century later, when a Croatian shepherd, whose spleen had been removed, rapidly succumbed to a disease caused by B. divergens. The first case in a healthy( immunocompetent) person was observed in the USA, on Nantucket Island, in 1969. The disease was caused by B. microti and the tick vector was I. scapularis. New cases appeared on the island and the disease was named Nantucket fever. Human infection with B. microti is almost as common as Lyme disease( borreliosis) in some areas of New England( 3).
Prevalence of babesiosis in Europe
Until publication of my Finnish article in 2014( 7), there was evidence of approximately 50 persons in Europe with clinical symptoms of babesiosis; most of them caused by B. divergens. A little surprisingly, more than half of these 50 persons are from France and the British Isles( 4). The disease is evidently very rare, but as it is poorly known in Europe many cases may occur without correct diagnosis( 8). Only two cases of human babesiosis have been described in Russia, both caused by B. microti( 4).
The microbe, piroplasm
B. microti is the cause of babesiosis in the USA, whereas in Europe the cause is mainly B. divergens. B. microti does not exist in the larvae of ticks, nor do the respective microorganisms of anaplasmosis and borreliosis. However, B. divergens can be found in this first stage of I. ricinus, and consequently in all 3 stages of sucking blood: larvae, nymphs and adult female ticks( 4).
Another question is which are the reservoir hosts; vertebrates“ giving” ticks their blood meal and having living piroplasms in their blood? To my astonishment I omitted to write about that in my Finnish article( 7). The explanation is that there was no comment regarding these( reservoirs) in the many reviews and other articles I read. Thus, work remains to be done!
Frequency of the protozoan in the tick
The reported infection prevalence varies from 0.9 % to 20 %; evidently this has not been sufficiently investigated by medi-
40 Forum for Nord Derm Ven 2017, Vol. 22, No. 2