Ulceroglandular tularemia in a toddler in Germany after a mosquito bite
- First Online:
- Cite this article as:
- Hanke, C.A., Otten, J., Berner, R. et al. Eur J Pediatr (2009) 168: 937. doi:10.1007/s00431-008-0862-3
Although tularemia is a long-known disease, its significance had diminished over the last decades in Middle Europe. However, over the past years, there is new evidence suggesting that tularemia has re-emerged in Germany. In 2007, the highest number of human cases for almost 50 years has been notified. Beside typical vectors, new ways of transmission seem to gain significance. So far, mosquito bite-transmitted tularemia has only been known from Scandinavia but not from Middle Europe.
We report the first case of a 1-year-old toddler from Southwestern Germany with mosquito bite-associated ulceroglandular tularaemia. The new and interesting features of this case are the young age of the patient and the unusual transmission route. The available data suggesting changes in the epidemiology for tularemia in Germany are reviewed. This is an interesting case of infantile tularemia with a very unusual transmission route, highlighting ongoing changes in the epidemiology of tularemia in Germany.
KeywordsTularemiaInfantFrancisella tularensis holarcticaMosquito biteGermanyEpidemiology
Tularemia, a zoonosis typically affecting humans, rodents, and smaller vertebrates, has been known for about 100 years. In recent years, it regained significance due to fears for its putative use as a biological warfare agent . In Germany, several lines of evidence indicate that tularemia has re-emerged since 2004. Besides outbreaks in primate facilities , the first outbreak in humans for more than 40 years has occurred in the vicinity of Darmstadt in late 2005 . In 2007, the highest number of human cases for almost 50 years has been identified .
The causative agent of tularemia is Francisella tularensis (FT), a Gram-negative, pleomorphic coccobacillus. Two subspecies are notorious for causing human infection, F. tularensis tularensis (type A) and F. tularensis holarctica (type B). Types A and B can both be found in Northern America, whereas only type B is endemic in Europe, Russia, some Northern Asian countries, and Japan. Both subspecies are transmitted to humans by direct contact with infected rodents, rabbits, and hares. Ticks and deer flies are known vectors for type A, whereas mosquitoes transmit type B in Northern Europe . So far, no mosquito-borne cases of tularemia have been reported from Germany. Furthermore, the few German cases that have come to medical attention during the last decades rarely included young children.
In the last decades, infected hares represented the main source of human infection in Germany, causing about 90% of all cases. But in 2007, more than 35% of the notified tularemia cases could not be attributed to contact with hares, and in many cases, the source of infection remained obscure .
In this report, we describe an unusual case of a toddler who developed ulceroglandular tularemia caused by F. tularensis holarctica after a mosquito bite in southwestern Germany. This first report of a putative mosquito-borne infection highlights current changes in the epidemiology of tularemia in Germany.
Laboratory confirmation of the F. tularensis infection
Pus (drained abscess)
16S rRNA gene
16S rRNA gene
RD1 PCR, gel- based
Chromosomal region RD1
924 bp fragment
30 bp deletion PCR, gel-based
Chromosomal region Ft-M19
220 bp fragment
Pus (drained abscess)
Cysteine heart agar, prolonged cultivation
Anti-F. tularensis lipopolysaccharide antibodies
We present the rare case of ulceroglandular tularemia in a 1-year-old boy, who is, to the best of our knowledge, the youngest tularemia patient ever described in Germany. The mode of transmission is most likely a mosquito bite, several of which had occurred at the time the primary lesion was noticed. The infection occurred in early October, a warm autumn period in which mosquitoes were still abundant in the upper Rhine Valley at the vicinity of Fribourg. At that time point, the mother had mosquito bites as well. No previous contact with pet animals, hares, or their excrements and no tick bites could be elicited as the toddler had been supervised indoors at home. There had been no signs of rodents in the family house in a suburban area. The family had not been traveling recently.
Generally, the clinical course of tularemia type B is often milder than with type A. However, clinical courses of type B tularaemia in children are more severe than in adults , and pulmonary involvement might be more common. Still, the ulceroglandular form of tularemia is most frequent, and lymphadenopathy and initial fever are typical symptoms in children with tularemia type B. Transmission of type B tularemia via mosquito bite has been repeatedly described from Scandinavia but not from Central Europe. The first isolation of F. tularensis from a child in Denmark was reported in 2005 and could be attributed to a tick bite . In our patient, transmission by a mosquito bite is most likely, as inflammation began at the respective lesion, and no other known potential modes of transmission could be identified in this patient. In Germany, only three to five human cases of tularemia per year used to be reported on average. In late 2005, the first outbreak for more than 40 years has been registered in participants of a hare hunt . In 2007 an increase to 21 reported cases was observed, of which 11 occurred in the southwestern state of Baden-Wuerttemberg . However, none of the other cases was directly linked to a mosquito bite. In one adult case, frequent stays in a forestal area were reported as the sole risk factor for acquiring the infection. Interestingly, this case was reported from the same county as our young patient.
The second reason making this case unusual is the young age of the affected boy. So far, no cases of infants have been reported in Germany, and generally few patients have been younger than school age . On the other hand, lymphadenopathy is very frequently observed in this age group, and routine workup does usually not include a specific test for F. tularensis. Blood cultures often remain negative. Serological testing has high sensitivity and specificity but is not widely established. In recent years, detection of FT by PCR has become another option, but again, availability is limited, and choosing the right primers is crucial . Both diagnostic tools were used in this presented case and brought conclusive positive results. However, the reason for specifically testing for tularemia came initially from an unspecific PCR test screening for eubacterial DNA in a swab from the incised lymph node. Hence, this might be a first diagnostic step but requires suitable specimen for testing.
The initial antibiotic treatment used in our patient was insufficient. Aminoglycosides have been the drugs of choice, but ciprofloxacin seems to be a very effective alternative for type B tularemia, even for very young patients . Our patient showed excellent recovery after surgical incision. Therefore, no further antibiotic treatment was initiated.
The presented case describes an uncommon presentation of tularemia in a very young child in Germany. Transmission seems to have occurred by mosquito bite, a vector that so far was known almost exclusively from Scandinavia. Diagnosis was delayed until surgical incision, but recovery occurred despite inadequate antibiotic treatment. The benign course was probably attributable to type B infection with only localized, ulceroglandular manifestation. Concerns remain whether this type of transmission will be seen more often in the future in Germany or other Central European countries. Medical professionals should therefore be aware of this diagnosis when treating young patients with lymphadenopathy and additional signs of infection.
This report complies with the ethical standards laid down in the 1964 Declaration of Helsinki.
Conflict of Interest
The authors declare that they have no conflict of interest.