[Insect-borne diseases and insect bites in Finland]. / Hyönteisten levittämät taudit ja puremat Suomessa.

Clinically significant endemic, arthropod-borne infectious diseases in Finland include Lyme disease, tick-borne encephalitis, tularemia and Karelian fever. The diagnosis of early borreliosis or tularemia is clinical and the treatment is initiated already before the results of eventual blood tests. The diagnosis of late stage borreliosis, tick-borne encephalitis or Karelian fever is confirmed mainly with serologic tests. The clinical significance of endemic anaplasmosis, Rickettsia helvetica, Inkoo and Uukuniemi viruses as well as anthropod-borne bunyaviruses and bartonelloses is either minor or remains open.

Performance assessment of a multi-epitope chimeric antigen for the serological diagnosis of acute Mayaro fever.

Mayaro virus (MAYV), which causes mayaro fever, is endemic to limited regions of South America that may expand due to the possible involvement of Aedes spp. mosquitoes in its transmission. Its effective control will require the accurate identification of infected individuals, which has been restricted to nucleic acid-based tests due to similarities with other emerging members of the Alphavirus genus of the Togaviridae family; both in structure and clinical symptoms. Serological tests have a more significant potential to expand testing at a reasonable cost, and their performance primarily reflects that of the antigen utilized to capture pathogen-specific antibodies. Here, we describe the assembly of a synthetic gene encoding multiple copies of antigenic determinants mapped from the nsP1, nsP2, E1, and E2 proteins of MAYV that readily expressed as a stable chimeric protein in bacteria. Its serological performance as the target in ELISAs revealed a high accuracy for detecting anti-MAYV IgM antibodies. No cross-reactivity was observed with serum from seropositive individuals for dengue, chikungunya, yellow fever, Zika, and other infectious diseases as well as healthy individuals. Our data suggest that this bioengineered antigen could be used to develop high-performance serological tests for MAYV infections.

Field evaluation of clinical features during chikungunya outbreak in Mayotte, 2005-2006.

BACKGROUND: To record and assess the clinical features of chikungunya fever (CHIKF), with a view to enable diagnosis based on clinical criteria rather than costly laboratory procedures in field conditions. METHODS: As part of a cross-sectional serologic survey conducted in Mayotte after a massive chikungunya outbreak in 2006, we collected data on clinical features of chikungunya infection and assessed the performance and accuracy of clinical case definition criteria combining different symptoms. RESULTS: Of 1154 participants included, 440 (38.1%) had chikungunya-specific IgM or IgG antibodies by enzyme-linked immunosorbent assay (ELISA). Of symptomatic participants, 318 (72.3%) had confirmed chikungunya, the dominant symptoms reported were incapacitating polyarthralgia (98.7%), myalgia (93.1%), backache (86%), fever of abrupt onset (85%) and headache (81.4%). There was a strong linear association between symptomatic infection and age (chi(2) for trend = 9.85, P < 0.001). Only 52% of persons with presumptive chikungunya sought medical advice, principally at public primary health care facilities. The association of fever and polyarthralgia had a sensitivity of 84% (95% CI: 79-87) and a specificity of 89% (95% CI: 86-91). This association allowed to classify correctly 87% (95% CI: 85-89) of individuals with serologically confirmed chikungunya. CONCLUSIONS: Our results suggest that the pair fever and incapacitating polyarthralgia is an accurate and reliable tool for identifying presumptive CHIKF cases in the field. These criteria provide a useful evidence base to support operational syndromic surveillance in laboratory-confirmed chikungunya epidemic settings.

Discriminating Tonate Virus from Dengue Virus Infection: A Matched Case-Control Study in French Guiana, 2003-2016.

Tonate virus (TONV) is an arbovirus discovered in 1973 in French Guiana (FG) belonging to the Venezuelan equine encephalitis virus complex, Alphavirus genus. Only few publications and cases have been reported in FG. The objectives of the present study were to describe the clinical picture of TONV and to compare its presentation with that of dengue virus (DENV). A retrospective study was performed in Cayenne hospital from 2003 to 2016 including all patients exclusively positive for TONV IgM and not for other alphaviruses. They were classified as high probability: typical clinical picture of arbovirus infection (i.e., fever, chills, headaches, muscle, and joint pains) and IgM seroconversion; medium probability: typical clinical picture + single positive IgM on a unique serum sample without control; and low probability: atypical clinical picture of infection and single positive IgM. Only patients with high and medium probability were included in the analysis and compared with a gender- and age-matched control group of DENV diagnosed by NS1 antigen (two controls per case). During the study period, 45 cases of TONV were included and compared with 90 cases of DENV. Twenty-eight (62.2%) were men; the median age was 34 years (IQ [22-49]). In the bivariate analysis, variables significantly associated with TONV versus DENV were the presence of cough (33.3% versus 10.3%) and anemia (32.5% versus 11.1%) and the absence of nausea (4.4% versus 32.2%), rash (2.2% versus 27.4%), fatigue (17.8% versus 41.0%), anorexia (6.7% versus 30.1%), muscle pain (42.2% versus 61.4%), headache (53.3% versus 70.8%), leukopenia (9.8% versus 44.4), and lymphopenia (42.5% versus 89.9%). There were no cases with severe neurological involvement, and there were no deaths. Tonate virus may be evoked as a cause of fever in patients living or returning from the Amazonian area. Positive TONV IgM does not prove the diagnosis and should not preclude from searching for alternative infectious diagnoses.

Development and evaluation of a 1-step duplex reverse transcription polymerase chain reaction for differential diagnosis of chikungunya and dengue infection.

Dengue (DEN) and chikungunya (CHIK) have emerged as the 2 most important arboviral infections of global significance. The similarities in clinical presentations, their circulation in the same geographic area, and the transmission through the same vector necessitate an urgent need for the differential diagnosis of these 2 infections. So far, no single assay is reported for differential diagnosis of these 2 infections. In this study, we report the development and evaluation of a 1-step single-tube duplex reverse transcription polymerase chain reaction (D-RT-PCR) assay by targeting E1 gene of CHIK and C-prM gene junction of DEN virus (DENV), respectively. The sensitivity of this assay was found to be better than conventional virus isolation and could detect as low as 100 copies of genomic RNA, which is equivalent to respective virus-specific RT-PCR. The evaluation was carried out with 360 clinical samples from recent CHIK and DEN outbreaks in India. This assay could also be able to detect dual infection of CHIK and DEN in 3 patients. The phylogenetic analysis based on the nucleotide sequencing of D-RT-PCR amplicon could precisely identify the genotypes of all the serotypes of DENV and CHIK viruses (CHIKV). These findings demonstrate the potential clinical and epidemiologic application of D-RT-PCR for rapid sensitive detection, differentiation, and genotyping of DENV and CHIKV in clinical samples.

Rapid affinity-purification and biotinylation of antibodies.

A simple and rapid method to affinity-purify and biotinylate antibodies was developed. The method utilizes separation of antigens by sodium dodecyl sulfate polyacrylamide gel electrophoresis, followed by transfer to nitrocellulose and binding of the antibodies to the specific antigen. The antibodies are biotinylated, while still bound to the antigen, thus avoiding the conjugation of the active antigen-binding sites of the antibodies. These antibodies have been successfully used in double-label immunofluorescence studies, but they should be likewise applicable in other immunological protocols.

Equine Getah virus infection: isolation of the virus from racehorses during an enzootic in Japan.

A primary enzootic of equine Getah virus infection involving 722 of 1,903 racehorses occurred at a training center in Japan between September and November of 1978. Sixty-two viral agents were isolated from the plasma of 209 sick horses which exhibited pyrexia with rectal temperatures ranging from 38.5--40 degrees C, urticarial rash on various portions of the body, and edema of the hind legs. The viruses were antigenically related to the AMM 2021, Haruna, and Sagiyama strains of Getah virus. Infection and disease were produced experimentally in horses when inoculated by the intramuscular or intranasal routes.

Antigenic relationships of flaviviruses with undetermined arthropod-borne status.

In contrast to most of the arthropod-borne flaviviruses, the flaviviruses with undetermined arthropod-borne status are probably disseminated only by direct contact with excreta (saliva, urine, feces, etc.); however, as yet undescribed arthropod transmission cycles may be found for some of them. Twenty-two of these flaviviruses, including prototype and recently isolated strains, were compared. Biologic properties were defined by infectivity titrations in suckling mice and Vero, LLC-MK2, and primary Pekin duck embryo cells, and antigenic relationships were defined by complement-fixation and plaque reduction neutralization tests. An antigenic classification scheme is proposed. Antigenic and biologic properties delimit two large clusters. The first, comprising a single antigenic complex, includes those which have yet to be isolated from arthropods, but are likely to be so (Israel turkey meningoencephalitis, Koutango, Negishi and Aroa viruses). The second, encompassing five antigenic complexes, is comprised of viruses which have been isolated exclusively from rodents or bats (Saboya, Carey Island, Dakar bat, Sokuluk, Bukalasa bat, Entebbe bat, Phnom Penh bat, Modoc, Sal Vieja, Jutiapa, San Perlita, Cowbone Ridge, Rio Bravo, Apoi, Tamana bat and Montana Myotis leucoencephalitis viruses) but includes three viruses (Saboya, Sokuluk and Entebbe bat viruses) which may be arthropod-borne, as indicated by replication in mosquito cells in vitro.

Febrile illness in Malaysia--an analysis of 1,629 hospitalized patients.

We studied 1,629 febrile patients from a rural area of Malaysia, and made a laboratory diagnosis in 1,025 (62.9%) cases. Scrub typhus was the most frequent diagnosis (19.3% of all illnesses) followed by typhoid and paratyphoid (7.4%); flavivirus infection (7.0%); leptospirosis (6.8%); and malaria (6.2%). The hospital mortality was very low (0.5% of all febrile patients). The high prevalence of scrub typhus in oil palm laborers (46.8% of all febrile illnesses in that group) was confirmed. In rural Malaysia, therapy with chloramphenicol or a tetracycline would be appropriate for undiagnosed patients in whom malaria has been excluded. Failure to respond to tetracycline within 48 hours would usually suggest a diagnosis of typhoid, and indicate the need for a change in therapy.

Comparison of an antibody-capture IgM enzyme-linked immunosorbent assay with IgM-indirect immunofluorescence for the diagnosis of acute Sindbis and West Nile infections.

The development and evaluation of an antibody-capture ELISA for the detection of IgM antibodies to Sindbis (SIN) and West Nile (WN) viruses are described. Comparison of the ELISA results with those obtained by indirect immunofluorescence (IIF) antibody tests using both fluorescein and biotinylated anti-human IgM conjugates, showed that the former technique was both more sensitive and specific than the IIF methods. There were no false positives by the ELISA whereas with the IgM-IIF assays a high percentage of false positives were obtained. These were due to rheumatoid factor and also to an interfering factor which was not detected by the RF latex agglutination test. Absorption of the sera with anti-IgG was necessary to eliminate this interference in the IgM-IIF tests.

Primer extension dideoxy chain termination nucleotide sequencing of partially purified RNA virus genomes: a technique for investigating low titre viruses with extensive genome secondary structure.

A modified version of the primer extension dideoxy chain termination nucleotide sequencing technique (Sanger et al., 1977) is described. This method has advantages over existing molecular cloning and primer extension techniques in that it allows the genome of RNA viruses to be directly sequenced from partially purified RNA preparations. Thus, viruses growing at unacceptably low titres in tissue culture can now be partially purified from infected mouse brain and sequenced. The technique also incorporates steps for the denaturation of secondary structure which has previously provided difficulties for primer extension sequencing.

Haemorrhagic manifestations with Sindbis infection. Case report.

Sindbis infection in man occurs rarely in Australia. Most recorded cases are either asymptomatic or result in a fever sometimes accompanied by a macular or vesicular rash. This case is of particular interest because of the severe haemorrhagic vesicular rash and the repeated recurrence of symptoms over a 5 month period together with the persistence of IgM antibodies to Sindbis virus.

Detection of Ross River virus immunoglobulin M antibodies by enzyme-linked immunosorbent assay using antibody class capture and comparison with other methods.

An enzyme-linked immunosorbent assay based on antibody class capture was developed for the detection of Ross River virus-specific immunoglobulin M antibodies (RRV IgM). The assay was specific, reproducible and precise. When compared with conventional tests for the detection of RRV IgM, such as hemagglutination inhibition following sucrose density gradient centrifugation and indirect enzyme-linked immunosorbent assay, the class capture assay was more sensitive. In 186 sera which were collected from 39 patients with RRV infection over a period of 1-4 yr from onset of initial symptoms, RRV IgM persisted for at least 1-2 yr. Sera were tested both at a single dilution from which the results were expressed as a binding index and in a dilution series in which they were expressed as an antibody titre. Binding index values gave better discrimination between sera collected during acute and later phases of the disease and may be of greater value than antibody titres in the diagnosis of RRV infection.

A destructive arthropathy following Chikungunya virus arthritis--a possible association.

Chikungunya virus arthritis is an acute severe polyarthritis following upon the bite of infected mosquitoes in endemic areas. With rapid air transport an increasing number of tourists are being exposed to potential infection. Whether tourists returning home in the incubation viremic stage can infect local mosquito populations in their home countries is unknown. Most cases recover from the severe joint pains within several weeks but up to 12% retain some residual joint symptoms for years. A case report is given of probable Chikungunya arthritis progressing to joint destruction before ultimately subsiding after 15 years leaving a sequela of destroyed metatarsal heads and late osteoarthritic changes in the ankles.

Pestivirus infection of ruminants in Australia.

Pestivirus infections are commonly diagnosed in cattle but are relatively uncommon in other ruminant species in Australia. Virus isolation is a very reliable technique for detecting pestivirus in specimens, especially when group reactive monoclonal antibodies are used with immunoperoxidase staining to detect non-cytopathogenic virus. Care must be taken to prevent adventitious pestivirus contamination of serum or cells used for cell culture. A recently developed antigen capture enzyme-linked immunosorbent assay has been extensively evaluated and found to be extremely accurate. This test is also much quicker and less expensive than virus isolation. Procedures are outlined to reliably certify animals to be free of pestivirus infection for export or as donors of semen or embryos.

[Development and use of an immunoenzyme technique for the routine diagnosis of the porcine reproductive and respiratory syndrome]. / Développement et utilisation d'une épreuve immuno-enzymatique pour le diagnostic courant du syndrome dysgénésique et respiratoire du porc.

An indirect enzyme-linked immunosorbent assay was developed for rapid detection of serum antibodies against the virus responsible for the porcine reproductive and respiratory syndrome (PRRS). This test is more sensitive than the reference technique (immunoperoxidase test applied to cultures of alveolar macrophages), particularly for detecting animals at the stage of seroconversion. It is also very specific for PRRS virus, because all specific hyperimmune sera against other porcine viruses, and all serum samples taken from herds before the disease appeared in western France were negative. The test has been used for routine diagnosis of PRRS. The results obtained during nine months from over 21,000 samples have confirmed the value of the test for diagnosis and epidemiological surveillance of the disease.

Border disease virus isolation from postpartum ewes.

The prevalence of border disease virus in a flock of Targhee sheep in southern Idaho was determined by serologic and virologic techniques. Of 249 ewes, 73 (29%) were seropositive to the antigenically related togavirus, bovine seropositive to the antigenically related togavirus, bovine viral diarrhea virus (BVDV). Concurrent testing of sera from 337 neonatal lambs indicated that 172 (51%) were seropositive for BVDV. It was observed that a high percentage (35%) of the BVDV-seropositive lambs were derived from seronegative ewes. Immunotolerance of the ewe was considered as the explanation for the lack of serologic relationship between seropositive lambs and their seronegative dams. Eleven cytopathogenic viruses were isolated from nasal and vaginal specimens obtained from 80 clinically healthy ewes within 24 hours of parturition. The viral isolates were demonstrated to be antigenically related to BVDV by direct immunofluorescence. Six of the 11 isolates were obtained from BVDV-seronegative ewes.

Modoc-like virus isolated from wild deer mice (Peromyscus maniculatus) in Alberta.

Small mammals were trapped in northeastern Alberta, Canada during 1976. Blood samples from these animals were tested for virus by inoculation of suckling mice. Blood clots from two deer mice yielded isolates of the same virus. The virus was related antigenically to a number of flaviviruses which have been isolated from mammals in Central America and North America and was related most closely to Modoc virus. Physical, chemical, and biological properties of the virus were similar also to those of Modoc virus. It did not produce illness or death in deer mice inoculated in the laboratory. Neutralization tests indicated that 1/38 (3%) red squirrels (Tamiasciurus hudsonicus), 3/35 (9%) least chipmunks (Eutamius minimus), 13/109 (12%) deer mice, and 3/50 (6%) humans were infected naturally. This is the first reported evidence of infection of red squirrels and chipmunks with a Modoc-like virus. These data extend the range of Modoc-like viruses northward by 1,500 km and comprise the first isolate from mammals in the boreal forest of Canada.

Turkey meningo-encephalitis in South Africa.

Turkey meningo-encephalitis is a neuroparalytic disease of turkeys first described and shown to be caused by a flavivirus in Israel. During 1978 a similar disease was observed in South Africa. In addition to the lesions described in Israel, myocarditis, regression of the ovary and egg peritonitis were constant findings. The similarity in host range, symptoms and pathological changes produced by the virus isolated locally and in Israel and the serological cross-reaction between the 2 virus isolates indicate that they are identical.

Flavivirus infections in Chiang Mai area, Thailand, in 1982.

Infection by JE virus still constitutes major cause of encephalitis in Chiang Mai Area, although some cases of possible dengue encephalopathy were observed. In spite of many apparent encephalitis cases, infection of vector mosquitoes by JE virus was not demonstrated. Virus isolation from hospitalized patients showed that the principal type of dengue virus circulating in Chiang Mai in 1982 was type 1 virus. Seroepidemiological survey on healthy humans indicated that the northern part of Chiang Mai Province in the region of the Maekong Valley has not yet been invaded so much by dengue viruses, compared with the Chiang Mai Valley, where dengue infection apparently became more prevalent than 12 years ago. The survey also indicated that the spread of JE virus in the study area was not uniform. Survey on vertebrates showed that anti-JE antibodies were highly prevalent among swine, horses, mules, sheep, and dogs. On the other hand, antibody prevalence was low in monkeys, ducks, and sparrows, and was negative among chickens and lizards. IgM-ELISA appeared to help differential diagnosis on JE from dengue even when the HI test did not give positive results.