Seroprevalence of Leptospira spp. in Working Horses Located in the Central Region of Chile

Urban working horses live in close contact with their owners. They are usually kept in periurban areas of big cities and cohabit with other animals under precarious sanitary conditions, whereas army horses are kept under controlled management and work. These characteristics leave urban working horses in higher risk of exposure to Leptospira spp. and could become a zoonotic risk for their owners. The aim of this study was to determine the frequency of seropositive working horses to diverse serovars of Leptospira spp. and compare them to a group of army horses. The microscopic agglutination test was used to assess the serum of 426 horses (160 working horses and 266 army horses) against two serovars of Leptospira borgpetersenii (Hardjo and Ballum) and four of Leptospira interrogans (Pomona, Canicola, Icterohaemorrhagiae, and Autumnalis). In the urban working horses group, 30.63% of horses were positive to at least one serovar at titers above 1:100, whereas 23.31% of the army horses were positive. The most frequent serovar in the working horse group was Ballum followed by Canicola, whereas in the army group was Autumnalis followed by Ballum. The serovars Hardjo, Pomona, and Icterohaemorrhagiae were not present in the army horses, whereas all serovars studied were detected in urban working horses. Although no horses studied presented clinical signs of leptospirosis, the study confirms exposure to Leptospira spp. and the importance of studying in more detail the livelihood conditions in which working horses are kept and possible risk of transmission to their owners.     

Leptospira spp. in horses in southern Brazil: Seroprevalence,infection risk factors,and influence on reproduction

Leptospirosis in horses is often associated with reproductive disorders. In the southern states of Brazil, horses are used for various jobs and cultural practices; nevertheless, serological surveillance for Leptospira is rare. Therefore, the objective of this study was to determine the seroprevalence of Leptospira spp. in horses in southern Brazil, as well as to identify the risk factors for infection and its impacts on reproduction. We performed microscopic agglutination tests for 12 serovars that corresponding 9 serogroup (Sejroe, Icterohaemorrhagiae, Australis, Pyrogenes, Pomona, Canicola, Grippotyphosa, Tarassovi and Ballum) in 595 samples from 60 herds. A brief history was obtained to analyze risk factors for reproductive disorders. A total of 45.9% of the tested horses were seropositive, of which the most frequent serogroups were Icterohaemorrhagiae (Icterohaemorrhagiae and Copenhageni serovars) and Ballum (Ballum serovar). Simple infections were found in 45.4% of seropositive animals, while mixed infections occurred in 54.6% of horses. There was a correlation between seropositivity and age and sex, that is, seropositivity was more frequent in animals over 6 years old and in females. There was no correlation between seropositivity and reproductive disorders. We conclude that there is a high seroprevalence of Leptospira spp. in southern Brazil with predominance of Icterohaemorrhagiae serogroup, mainly in older animals. Location, breeds, contact with dogs or other domestic animals are not risk factors, whereas gender is a risk factor. Reproductive disorders are not due to leptospirosis in the study region.     

Prevalence of serum antibodies against six Leptospira serovars in healthy dogs

OBJECTIVE: To determine the prevalence of antibodies against 6 Leptospira serovars and determine risk factors associated with positive Leptospira titers in healthy client-owned dogs in Michigan. DESIGN: Cross-sectional study. ANIMALS: 1,241 healthy dogs at least 4 months of age. PROCEDURES: Dogs were examined by veterinarians at private practices. Vaccinated and unvaccinated dogs were enrolled in the study, which occurred prior to the availability of a 4-serovar (Canicola, Grippotyphosa, Icterohaemorrhagiae, and Pomona) Leptospira vaccine. Sera were tested by use of the microscopic agglutination test to determine antibody titers against Leptospira serovars Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona. A questionnaire was used to collect demographic information about each dog to identify risk factors associated with seropositive status. RESULTS: 309 of 1,241 (24.9%) dogs had antibody titers against at least 1 of the 6 Leptospira serovars, which suggested exposure to Leptospira spp. Prevalence of antibodies was highest to serovar Grippotyphosa, followed by Bratislava, Canicola, Icterohaemorrhagiae, and Pomona. Age, travel outside Michigan, exercise outside fenced yards, and exposure to livestock and wildlife were significant risk factors for positive titers. CONCLUSIONS AND CLINICAL RELEVANCE: Among healthy dogs from the lower peninsula of Michigan, > 20% have antibodies against leptospiral serovars historically considered uncommon but more recently incriminated as causing clinical canine leptospirosis. Wildlife and livestock may be of increasing importance as reservoirs for canine leptospirosis as urbanization continues to occur. Expanded vaccination strategies may partially mitigate these trends.     

Canine leptospirosis—Do we have a problem?

Acute canine leptospirosis is well known to vet surgeons. To protect dogs against this lethal disease, vaccination is widely used. However, chronic forms of leptospirosis have been noticed even in vaccinated animals, generally induced by bacteria from serogroups other than Icterohaemorrhagiae and Canicola such as Sejroë, Australis or Grippotyphosa. In a survey on 98 ill cats, 48% were positive in microagglutination test (MAT) to Leptospira spp., showing that this infection is also frequent in the feline species.     

Prevalence of Leptospira interrogans antibodies in free-ranging Tayassu pecari of the Southern Pantanal, Brazil, an ecosystem where wildlife and cattle interact

We surveyed a wild population of white-lipped peccaries (Tayassu pecari) in the Brazilian Pantanal for evidence of Leptospira interrogans. Serum samples from 71 free-ranging T. pecari were obtained between 2003 and 2005 in the southern Pantanal of Mato Grosso do Sul state. We used microscopic microagglutination to test for antibodies against 14 L. interrogans serovars (antibody titers ≥1:100 were considered seropositive). Seventy percent of captured animals tested positive for leptospirosis antibodies. Antibodies against icterohaemorrhagiae and autumnalis serovars were the most prevalent. We used log-linear analyses to test for associations among seropositivity, age class, and sex of captured animals. Seropositivity was strongly associated with animal age class, but independent of sex. Forty-six percent of animals less than 2 years old, 63% of adults during peak reproductive years, and 100% of the oldest age class were seropositive. A nonparametric multivariate procedure (MRPP) showed that the composition of serovar antibody types changed with age, and ANOVA models demonstrated that antibody titers increased with age, suggesting long-term exposure to a greater number and variety (i.e., serovar types) of L. interrogans infections. This study presents the first quantitative survey of antibodies against L. interrogans serovars in a T. pecari population of the Pantanal. The high prevalence of leptospirosis antibodies in free-ranging white-lipped peccaries and the potential impacts on reproduction and population dynamics emphasize the need for further studies investigating the roles of Pantanal wildlife and livestock in the transmission and maintenance of L. interrogans in the environment.     

A serological survey of antibodies to Leptospira species in dogs in South Africa

Leptospirosis, a disease more common in the tropics, can cause a life-threatening multisystemic syndrome in humans and animals. Immunity, whether natural or vaccine-induced, is serogroup-specific with the infecting serovars varying according to geographical locality. In South Africa, in spite of the fact that the bacterin vaccine for some Leptospira serovars is often used, there is no recent information on the incidence of canine leptospirosis as well as the infecting serovar/s. The aim of this study, which was undertaken on sera collected in 2008 and 2009 from both strays and owned dogs predominantly in the coastal regions of South Africa, was to determine the presence of leptospiral antibodies to 15 serovars known to infect dogs. Of the 530 samples tested, 25 tested positive to 7 different serovars with the microscopic agglutination test (MAT). Nine of the 25 samples tested positive to more than one serovar. The 2 serovars most frequently represented were Canicola, which reacted to 17 sera, and Pyrogenes, which reacted to 10 sera. Currently the only vaccines available in South Africa in different combinations contain serovars Canicola, Icterohaemorrhagiae, Pomona and Grippotyphosa. The results showed that the use of vaccines containing serovar Canicola is still justifiable in certain regions of the country. However, the presence of antibodies to serovar Pyrogenes in several dogs, pending a broader investigation, indicates that this serovar should also be included in the range of Leptospira vaccines for use in South Africa.     

Leptospirosis in farmed deer in New Zealand : a review

Current knowledge of leptospirosis in farmed deer in New Zealand is reviewed. Over the past 25 years, leptospirosis has been reported to occur in individual cases as well as in herd outbreaks in farmed deer and in human cases linked to farmed deer. Serological studies and evidence from bacterial culture suggest infection is widespread. Mixing of young stock from several sources appears to be a significant risk factor for outbreaks. The culture of Leptospira interrogans serovars Hardjobovis, Pomona and Copenhageni has been reported. Infection with serovar Hardjobovis had the highest prevalence, either individually or mixed with serovar Pomona. Infection with serovar Copenhageni appears uncommon and its pathogenicity in deer is unproven. Titres to serovars Australis, Ballum, Balcanica and Tarassovi have been reported. Deer appear to be maintenance hosts for serovar Hardjobovis, incidental or accidental hosts and probably a maintenance population for serovar Pomona, since some infections persist for several months, and accidental hosts for serovar Copenhageni. Serovar Pomona appears to produce clinical and probably subclinical disease, whereas serovar Hardjobovis appears to cause only subclinical disease, although the relative risk of disease causation has not been determined. Clinical disease is usually manifested by haemolysis, jaundice, renal lesions, haemoglobinuria and often by sudden death. Renal lesions are commonly observed at slaughter and many are associated with leptospiral infections. Occupationally, slaughterhouse workers appear to be at greatest risk of contracting the disease from deer. Vaccination produces serological responses, but its effectiveness in protecting against disease, and prevention or reduction of shedding in urine, has not yet been confirmed in deer. More robust knowledge of the epidemiology of leptospiral infections in deer, and the effectiveness of vaccines and vaccination regimes, is needed to assist the deer industry to develop a strategy to manage this disease.     

Serological survey for antibodies to Leptospira in dogs and raccoons in Washington State

A high number of reported canine leptospirosis cases occurred in Washington State from 2004 to 2006. This prompted a serosurvey of healthy dogs from around the state to determine the distribution of exposure risk and to provide insight into serovar epidemiology in the region. In addition, a convenience sample of sera from injured raccoons was also tested, and clinical serological data from the Washington Animal Disease Diagnostic Laboratory were examined. The proportion of dogs with an antibody titre (>or=1:100) to any serovar was 27/158 (17.1%, 95% CI 11.6-23.9), and that proportion among raccoons was 22/115 (19.1%, 95% CI 12.4-27.5) suggesting that the potential for exposure in Washington state is not uncommon. The most frequently detected serovars in healthy dogs were Autumnalis, Icterohemorrhagiae and Canicola, in clinical canine samples Autumnalis, Bratislava and Pomona were more frequent and in sick or injured raccoons Autumnalis, and Pomona were most frequently detected. Clinical canine serology demonstrated a late summer-fall seasonality that was consistent with other reports. An outbreak of canine leptospirosis occurred during 2004-2006 and was located primarily in western Washington counties, as were three reported human cases in 2005. Canine leptospirosis surveillance is an important tool for detecting human risk of exposure and may provide insights into which serovars are currently of clinical importance.     

Characterization of Leptospira infection in suckling and weaning rat pups

Rats are known to be the most important reservoirs of Leptospira spp. However, the leptospiral dose and age at which rats become resistant to Leptospira infection are not yet well elucidated. Aimed to characterize leptospirosis in rat pups, we found that suckling pups (4-, 7-, and 14-day old) are susceptible to leptospires and resistance starts from the weaning age (23-day old). Susceptibility of rat pups was also affected by the infecting dose of the organisms. Jaundice, decrease in body weight, and neurological symptoms prior to moribundity was evident in infected suckling pups. However, 23-day-old infected pups did not manifest any pathological changes and were able to survive the infection similar to adult rats. Based on these results, we propose the suckling rat pup as a novel animal model of human leptospirosis to investigate pathogenesis, development of host resistance, and the mechanisms involved in rats becoming maintenance hosts for leptospires.     

Occurrence of anti-<Emphasis Type="Italic">Leptospira</Emphasis> spp. antibodies in <Emphasis Type="Italic">Rhipidomys</Emphasis> spp. from a forest fragment of the Brazilian Cerrado

Leptospirosis is a zoonotic disease of world importance, and its transmission depends on the interaction between humans and animals. Given the necessity to investigate potential hosts of Leptospira spp., this study verified the prevalence of different serovars in the species of Rhipidomys spp., a widespread sigmodont rodent in Brazil. The studied population originates from a semi-evergreen forest located in the county of Uberlândia, in the state of Minas Gerais. The microscopic agglutination test (MAT) was performed with 14 serovars. Thirteen out of the 43 wild rodents captured showed a positive agglutination reaction, with a greater prevalence of the serovars Pyrogenes, Copenhageni, and Canicola. This study found a prevalence of 30.3% anti-Leptospira spp. antibodies; all positive animals were reactive to more than one serovar.     

Epidemiology of leptospirosis in North-Central Italy: Fifteen years of serological data (2002–2016)

Leptospirosis is a re-emerging bacterial zoonosis. North-Central Italy is characterized by a geographic area that promote Leptospira circulation. Data on sero-epidemiological survey carried out from 2002 to 2016 in North-Central Italy were reported and discussed. Overall, 709 out of the 8488 (8.35%) tested sera were positive for Leptospira at the cut-off titer (1:100) and 218 (2.57%) at higher titer (≥1:400). The highest percentages of positivity was recorded for coypus (22.86%), swine (19.74%) and bovine (13.03%). Pomona and Australis resulted the serogroup more often detected, followed by Sejroe and Icterohaemorrhagiae; while, a low number of positive sera was detected for serogroups Ballum, Canicola and Tarassovi. Percentage of positive sera for each year slightly decreased from 2002 to 2008 and rose from 2009. High percentages of positive reactions were recorded in 2014 (17.23%), 2015 (19.61%) and 2016 (38.05%). In conclusion, the results of this investigation reported an increase of leptospirosis in North-Central Italy. Furthermore, several animals resulted infected as accidental hosts by unusual Leptospira serovars. These data could suggest a change in host range for some serovars, that may promote the adaptation to new hosts.     

Serological survey of pre-weaned New Zealand fur seals (Arctocephalus forsteri) for brucellosis and leptospirosis

AIM: To conduct a longitudinal serological survey for evidence of Brucella spp and Leptospira spp infection of pre-weaned New Zealand fur seals in a colony on the Otago Peninsula. METHODS: Seal pups were repeatedly captured on a monthly basis from February through to July 2001. Pups were tagged at first capture and a blood sample was taken at each capture event. A total of 163 sera were collected from 118 seal pups. Where sufficient volume was collected, the sera were tested for leptospirosis using the microscopic agglutination test (MAT), and for brucellosis using the competitive enzyme-linked immunosorbent assay (ELISA) for Brucella abortus. RESULTS: None of 128 sera from 101 seals tested positive to the ELISA for B. abortus. All tests for Leptospira interrogans serovars Grippotyphosa, Copenhageni, Bratislava and Leptospira borgpetersenii serovar Ballum were negative at a cut-off of <1/100 dilution. Positive or suspicious titres were found to L. interrogans serovars Canicola and Pomona and L. borgpetersenii serovar Hardjo. The highest titres (12,800) were found to serovar Pomona. The titre to serovar Pomona in one seal rose from <1/50 in March to 12,800 in April and was <1/50 when re-sampled in July. The titre to serovar Pomona in another seal dropped from 12,800 in May to <1/50 in June. These seals also had titres to serovar Hardjo, which rose or fell in the same manner. All suspicious or positive titres occurred in late April and early May, when the pups were approximately 4-5 months old. In June and July, all seals tested were negative. CONCLUSIONS: There was no serological evidence of Brucella infection in the pre-weaned fur seals at the colony. Positive titres to serovars Pomona, Hardjo, or Canicola suggest that a Leptospira species was present at the colony, however isolation or visualisation of the organism is required to confirm this. Care should be exercised when handling New Zealand fur seals to prevent human infection or inadvertent transfer of leptospirosis to another marine mammal species.     

Hypomagnesaemia in cattle

Leptospirosis is an important animal and human health problem in New Zealand, and the epidemiological and ecological aspects of infection in domestic species and free-living species are described. The characteristics of infection with a particular serovar are often considerably different in different species of animal and primary epidemiological investigations involve differentiating between maintenance-host populations and accidental-host populations for the serovars present in a particular ecosystem.

Cattle and pigs are maintenance hosts for hardjo and pomona respectively. Balcanica is maintained by possums (Trichosurus vulpecula) and ballum is maintained by the house mouse (Mus musculus), ship rat (Rattus rattus) and hedgehog (Erinaceus europaeus). In some regions, foci of copenhageni infection are maintained by Norway rats (Rattus norvegicus). Each serovar shows a high degree of parasitic adaption to its maintenance-host species and this is reflected in the nidality of leptospirosis in intensive farming environments. Accidental infections in domestic animals and man are the consequence of ecological associations with maintenance-host populations for particular serovars.

Control of leptospirosis in domestic animals depends on decreasing the prevalence of infection with serovars maintained within populations of domestic animals, and decreasing the degree of ecological association with free-living maintenance-host populations. Vaccination of cattle against hardjo. will considerably reduce the prevalence of infection in vaccinated herds and therefore decrease the prevalence of accidental hardjo infections in man.     

Serological survey of pre-weaned New Zealand fur seals (Arctocephalus forsteri) for brucellosis and leptospirosis

AIM: To conduct a longitudinal serological survey for evidence of Brucella spp and Leptospira spp infection of pre-weaned New Zealand fur seals in a colony on the Otago Peninsula.

METHODS: Seal pups were repeatedly captured on a monthly basis from February through to July 2001. Pups were tagged at first capture and a blood sample was taken at each capture event. A total of 163 sera were collected from 118 seal pups. Where sufficient volume was collected, the sera were tested for leptospirosis using the microscopic agglutination test (MAT), and for brucellosis using the competitive enzyme-linked immunosorbent assay (ELISA) for Brucella abortus.

RESULTS: None of 128 sera from 101 seals tested positive to the ELISA for B. abortus. All tests for Leptospira interrogans serovars Grippotyphosa, Copenhageni, Bratislava and Leptospira borgpetersenii serovar Ballum were negative at a cut-off of <1/100 dilution. Positive or suspicious titres were found to L. interrogans serovars Canicola and Pomona and L. borgpetersenii serovar Hardjo. The highest titres (12,800) were found to serovar Pomona. The titre to serovar Pomona in one seal rose from <1/50 in March to 12,800 in April and was <1/50 when re-sampled in July. The titre to serovar Pomona in another seal dropped from 12,800 in May to <1/50 in June. These seals also had titres to serovar Hardjo, which rose or fell in the same manner. All suspicious or positive titres occurred in late April and early May, when the pups were approximately 4–5 months old. In June and July, all seals tested were negative.

CONCLUSIONS: There was no serological evidence of Brucella infection in the pre-weaned fur seals at the colony. Positive titres to serovars Pomona, Hardjo, or Canicola suggest that a Leptospira species was present at the colony, however isolation or visualisation of the organism is required to confirm this. Care should be exercised when handling New Zealand fur seals to prevent human infection or inadvertent transfer of leptospirosis to another marine mammal species.     

New topics on leptospirosis

In the United States, leptospirosis takes the second place in human diseases transmitted by animals. The clinical features of leptospirosis are very various in man and domestic animals by the nature of the serovar involved and the animal species infected. There are many epidemiological cycles of leptospirosis but environmental conditions are always important.     

Diagnostic accuracy of an in-house ELISA using the intermediate species Leptospira fainei as antigen for diagnosis of acute leptospirosis in dogs

Diagnosis of animal leptospirosis is still challenging. The microscopic agglutination test, is the current method for diagnosing leptospirosis. However, this technique requires specific equipment, highly trained staff and the maintenance of live cultures of several reference strains of Leptospira for use as antigens. Recently, an ELISA (enzyme-linked immunosorbent assay) employing a Leptospira fainei serovar Hurstbridge based antigen for the early diagnostic of human leptospirosis was developed. In this study we estimate the diagnostic sensitivity and specificity of this test in identifying acute canine leptospirosis. A total of 271 serum samples divided into five panels and tested by MAT as a reference test, were used to evaluate the ELISA. Comparing acutely and non-acutely infected dogs, ELISA-Hb showed 95.6% sensitivity and 93% specificity. L. fainei-based ELISA is adequate for diagnosing acute canine leptospirosis, with high sensitivity and specificity and presenting practical advantages when compared to current techniques.     

Serovar identification, antimicrobial sensitivity, and virulence of Avibacterium paragallinarum isolated from chickens in Thailand

Avibacterium paragallinarum causes infectious coryza in chickens, an acute respiratory disease that has worldwide economic significance. The objectives of this study were to determine the serovars, antimicrobial resistance, and pathogenicity of A. paragallinarum isolated from chickens in Thailand. Eighteen field isolates of A. paragallinarum were confirmed by PCR. When examined by serotyping in a hemagglutination inhibition test, 10 isolates were serovar A, five isolates were serovar B, and three isolates were serovar C. The susceptibility of the isolates to 16 antimicrobial agents was tested by a disk diffusion method. All isolates were susceptible to amoxicillin-clavulanic acid. There was a high level of resistance to lincomycin and erythromycin. All isolates were resistant to cloxacillin and neomycin. A study of bacterial entry into, and survival within, chicken macrophages showed variation between isolates but no clear connection to serovar. A virulence test was performed by challenging 4-wk-old layers via the nasal route with 400 dl of bacteria (10(8) colony-forming units/ml). Clinical signs were observed daily for 7 days, and the birds were subjected to a postmortem necropsy at 7 days postchallenge. All 18 field isolates caused the typical clinical signs of infectious coryza and could be re-isolated at 7 days after challenge. There was no significant difference in the clinical scores of the isolates except that two isolates (112179 and 102984, serovars A and B, respectively) gave a significantly higher score than did isolate CMU1009 (a serovar A isolate). No correlation between serovar and severity of clinical signs was found.     

Current status of leptospirosis in Japan and Philippines

Leptospirosis is an acute febrile illness with a wide variety of clinical manifestations and is encountered throughout the world, prominently in tropical areas with high rainfall. In this paper, we review the current status of leptospirosis in two Asian countries, Japan and Philippines, which have quite different situations in terms of economy, environment, infrastructures and prevailing infectious diseases. In Japan, until 1960, more than 200 deaths due to leptospirosis had been reported yearly. After 1960, the number of reported cases had rapidly decreased. Now, leptospirosis cases notified every year were less than 20. After the early 1960s, modernization of agriculture was introduced, at the same time, inactivated vaccine against Leptospira was applied for humans and there was good maintenance of infrastructures such as water works and sewage systems.

In Philippines, on the other hand, leptospirosis patients tend to be frequently found in flood-prone areas of urban setting such as Metro Manila, which was found to be the endemic foci of leptospirosis. Morbidity in a rural area (Cabatuan, Iloilo) was 147 cases per 100,000 populations. From 1998 to 2001, about 70% of 1200 suspected leptospirosis patients in Philippines were serologically positive. The average age of patients was 32 years old where 87% of the cases were males and 70% were outdoor workers. Case fatality rate was found to be 12–14%. The estimated major serovars in Metro Manila and neighboring provinces were Manilae, Losbanos, Tarassovi, Poi and an unknown serovar. Outbreaks of leptospirosis in the Philippines are thought to be associated with heavy rainfall, rapid urbanization (dramatic increase in populations), deforestation, increasing number of flood-prone areas, poor infrastructures and many others.     

Leptospire infections in pigs: epidemiology, diagnostics and worldwide occurrence

Leptospirosis is a systemic disease affecting humans and animals, and pigs are generally considered the reservoir host species for the serovars Pomona, Bratislava and Tarrasovi. Endemic infections in swine herds generally remain subclinical, as do the vast majority of leptospire infections. However, when a susceptible breeding herd is infected for the first time or its immunity is compromised, considerable losses can occur due to abortion, stillbirths, weakly piglets or infertility. Infections in pigs caused by other serovars tend to occur only incidentally, vary regionally, and depend on other reservoir hosts, primarily rodents. Leptospires persist in porcine kidneys, and the Bratislava serovar, in the genital tract; it is excreted in urine and genital fluids. Leptospirosis is transmitted by direct or indirect contact with an infected animal. Fundamental research on porcine leptospirosis was conducted in the 1970s and 1980s. However, despite subsequent application of the most recent molecular biological methods, the pathogenesis of porcine leptospirosis is still largely unknown, and research results from the last 25 years on its incidence are very heterogeneous, due not only to regional differences but also to differences in the evaluation of diagnostic and population studies. Serological testing of pigs showed serovar prevalences ranging between as much as 16.3% (Pomona) and generally no more than 2.9% (Tarassovi), whereas antibodies against Bratislava were found in as many as 41.8% of pigs tested during the last 20 years, as in previous studies, indicating that this remains the most prevalent serovar.     

Characterization of Haemophilus parasuis isolated from Brazilian swine through serotyping, AFLP and PFGE

Haemophilus parasuis infection in pigs is characterized by fibrinous polyserositis, arthritis and meningitis. Despite the fact that traditional diagnosis is based on herd history, clinical signs, bacterial isolation and serotyping, molecular-based methods are alternatives for species-specific tests and epidemiological studies. The aim of this study was to characterize H. parasuis field strains from different states of Brazil, employing serotyping and genotyping methods. Serotyping revealed that serovar 4 was the most prevalent (26.1%), followed by serovars 5 (17.4%), 14 (8.7%), 13 (4.4%) and 2 (4.4%), whereas 39% of the strains were considered as untypeable. AFLP with a single enzyme and PFGE were able to type all isolates tested, generating 34 and 20 different profiles, respectively, including untypeable strains. Besides the slightly higher discrimination index presented by AFLP, PFGE with Not I restriction enzyme showed a better correlation with epidemiological data, grouping strains of the same serovar, animal or farm origin. The results indicated AFLP and PFGE as valuable tools for typing H. parasuis isolates collected in Brazil.