Transmission by other vectors than ticks / other bloodsucking insects?:  

Erythema chronicum migrans (Afzelli) associated with mosquito bite.
Hard S.
Acta Derm Venereol (Stockh) 1966; 46:473-476. PMID: 4163724
No abstract. Paper reports unsucces in demonstrating spirochetes ad modum Lennhoff and not being able to transfer the disease via ticks fed on EM.
Reports a female case, with latent syphilis, who was never exposed to ticks, since she lived way north of the tick-border in Sweden, who developed multiple ECM after mosquito bites in 1959; no general symptoms. Lesion subsided on 600.000 units penicillin x 2. She was well during 1960, but in she presented with the same history and lesions as before, 600.000 units penicillin for four days. Same story again in seen by the author who took picture of multiple EMs of varying size; typical ECM histology. [good pictures of EM presented in article] The available literature contains no report of a case with so many lesions on so many occasions."

Lyme disease in Canada with possible transmission by an insect.
Doby JM, Anderson JF, Couatarmanac'h A, Magnarelli LA, Martin A.
Zentralbl Bakteriol Mikrobiol Hyg A 1987 Feb; 263(3): 488-90 PMID: 3591106
The first documented case of Lyme disease to have originated in Canada is presented. A 51-year old French female nurse visited Quebec, Canada from 20 July to 5 August, 1984 and contracted Lyme disease. She reported an insect bite on 3 August 1984 on the back of her knee with erythema chronicum migrans appearing at the site of the bite on 5 August 1984. The patient presented with meningeal lymphocytic reaction near the end of September, 1984. Total Ig serum titers in indirect immunofluorescence tests on 1 October 1984, 10 October 1984, and 10 January 1985 were 1/512, 1/2048 and 1/16,384, respectively.

Isolation of the spirochaete Borrelia afzelii from the mosquito Aedes vexans in the Czech Republic.
Halouzka J, Postic D, Hubalek Z.
Med Vet Entomol 1998 Jan; 12(1): 103-5 PMID: 9513946

During the years 1993-1995, a total of 3580 culicine mosquitoes of six species were collected in South Moravia, Czech Republic, and examined by dark-field microscopy for the presence of borreliae. Females of Aedes cantans, Ae. sticticus, Ae. vexans, Culex pipiens and Cx pipiens biotype molestus (but not Ae. geniculatus or Culiseta annulata) harboured spirochaetes, the frequencies ranging from 0.7% to 7.8%. One isolate (BR-53) from Ae. vexans was identified as Borrelia afzelii genospecies. The potential role of mosquitoes in the epidemiology of Lyme borreliosis should be investigated.    

[Etiologic and epidemiologic questions posed by erythema chronicum migrans and Lyme disease. Apropos of 4 cases at the Regional Hospital Center, Rennes] 
Doby JM, Chastel C, Couatarmanac'h A, Cousanca C, Chevrant Breton J, Martin A, Legay B, Guiguen C.  
Bull Soc Pathol Exot Filiales 1985; 78(4): 512-25 PMID:
4075471
The authors give 4 observations, made in Rennes (France), of 3 cases contracted in France and 1 in Canada, cases they think to be related, for 3 at least, to the infectious entity described by American authors under the name of Lyme disease. If 1 of these cases was limited to an erythema chronicum migrans, the 3 others showed a beginning evolution towards a classical Lyme disease. In 2 of these 3 last cases, the infection was perhaps cut short by a quickly applied therapy by antibiotics.They discuss the different hypotheses about the negative Borrelia serologic reactions in 3 of the 4 cases. A possible arboviral aetiology is evocked. In only one of the 4 cases, a tick-bite can be asserted, the role in the the transmission of this kind of arthropods being strictly excluded in 2 of the 3 other cases (transmission likely by a mosquito and by a biting fly (tabanid?)). The authors put the question of the possibility of transmission, for erythema chronicum migrans and Lyme disease, by arthropods other than ticks.    

Investigation of haematophagous arthropods for borreliae summarized data, 1988-1996.
Hubalek Z, Halouzka J, Juricova Z
98178065 Folia Parasitol Praha 1998; 45(1): 67-72 
PMID: 9516997
Blood-sucking arthropods, collected in South Moravia, Czech Republic, were examined by darkfield microscopy for borreliae from 1988 to 1996. Among host-seeking ixodid ticks (8481 Ixodes ricinus (L.), 372 Dermacentor reticulatus (Fabr.), 167 Haemaphysalis concinna Koch), borreliae were only observed in adult (23.2%), nymphal (17.2%) and larval (6.3%) I. ricinus. The prevalence of borreliae in I. ricinus did not vary considerably among habitats except for lower values in agroecosystems, xerothermic oak woods and grasslands. The frequency of intensity of spirochaetal infection (log10 counts of borreliae per tick) in I. ricinus approximated the negative binomial distribution. The proportions of host-seeking female and nymphal ticks containing > 100 borreliae were 5.0% and 1.7%, respectively. Among preimaginal ticks (749 I. ricinus, 222 D. reticulatus, 82 H. concinna) parasitizing free-living forest birds and small mammals, borreliae were detected in 6.1% of larval and 10.3% of nymphal I. ricinus, and in one larval H. concinna; 3.2% of the birds and 19.4% of the mammals carried infected ticks. Among 3464 female mosquitoes (Culicidae) of 6 species, 4.1% contained spirochaetes: 1.4% of Aedes vexans Meig., 1.3% of A. cantans (Meig.), 2.2% of A. sticticus (Meig.), 2.2% of Culex pipiens pipiens L. and 5.9% of C. p. molestus Forskal. Borreliae were also detected in 8.4% of 142 fleas (Siphonaptera, largely Ctenophthalmus agyrtes Heller and Hystrichopsylla talpae Curtis) collected from small mammals. Twelve isolates of B. burgdorferi sensu lato have been identified to genospecies: 6 strains from I. ricinus (4 Borrelia garinii Baranton et al., 1 B. afzelii Canica et al. and 1 B. lusitaniae Le Fleche et al.), 1 strain from A. vexans (B. afzelii), 2 strains from C. agyrtes (B. afzelii), and 3 strains from host rodents (B. afzelii).  

Ticks and biting insects infected with the etiologic agent of Lyme disease, Borrelia burgdorferi.
Magnarelli LA, Anderson JF.
J Clin Microbiol 1988 Aug; 26(8): 1482-6 PMID:
3170711
Members of 18 species of ticks, mosquitoes, horse flies, and deer flies were collected in southeastern Connecticut and tested by indirect fluorescent-antibody staining methods for Borrelia burgdorferi, the etiologic agent of Lyme disease. An infection rate of 36.2% (116 tested), recorded for immature Ixodes dammini, exceeded positivity values for all other arthropod species. Prevalence of infection for hematophagous insects ranged from 2.9% of 105 Hybomitra lasiophthalma to 14.3% of seven Hybomitra epistates. Infected I. dammini larvae and nymphs coexisted with infected Dermacentor variabilis (American dog tick) immatures on white-footed mice (Peromyscus leucopus), but unlike I. dammini, none of the 55 adult American dog ticks collected from vegetation harbored B. burgdorferi. Groups of 113 field-collected mosquitoes of Aedes canadensis and 43 Aedes stimulans were placed in cages with uninfected Syrian hamsters. Of these, 11 females of both species contained B. burgdorferi and had fed fully or partially from the hamsters. No spirochetes were isolated from the hamsters, but antibodies were produced in one test animal.

Borrelia burgdorferi detected by culture and PCR in clinical relapse of disseminated Lyme borreliosis.
Oksi J, Marjamaki M, Nikoskelainen J, Viljanen MK.
Ann Med 1999 Jun;31(3):225-32 PMID:
10442678
In this paper some of the patients didn't recall a tick bite, but these patients was sure it was a horsefly-like stinging insect that gave them the disease.