Evidence Of Human Infection Research Articles

SARS-CoV-2 in Namibian Dogs

The pandemic of coronavirus disease 19 (COVID-19) has focused the attention of researchers, and especially public opinion, on the role of the human-animal-environment interface in disease emergence. At the beginning of the COVID-19 pandemic, media reports regarding the role of pets in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused significant concern and social anxiety. Although nowadays proven negligible in developed countries, essentially no studies have been performed in low-income African areas where companion animals are often raised differently from high income countries, and the contact patterns occurring in these scenarios could affect the epidemiological scenario. An extensive molecular biology survey was performed from March 2022 to September 2022 on Namibian dogs residing in urban and rural areas, showing a low but not negligible SARS-CoV-2 prevalence (1%; 95CI: 0.33-2.32%) of 5 out of 500. In only one instance (i.e., a 4-year-old female Labrador) was there a clear association that could be established between the infections of the owner and animal. In all other cases, no evidence of human infection could be obtained and no episodes of COVID-19 were reported by the owners. Although no consistent evidence of pet-to-pet transmission was proven in the present study, a cautionary principle suggests intensive and dedicated investigation into companion animal populations, especially when animal contact is frequent and a particularly susceptible population is present.

Evidence for human infection with avian influenza A(H9N2) virus via environmental transmission inside live poultry market in Xiamen, China.

H9N2 avian influenza virus (AIV) has become prevalent in the live poultry market (LPM) worldwide, and environmental transmission mode is an important way for AIVs to infect human beings in the LPM. To find evidence of human infection with the influenza A(H9N2) virus via environmental contamination, we evaluated one human isolate and three environmental isolates inside LPMs in Xiamen, China. The phylogeny, transmissibility, and pathogenicity of the four isolates were sorted out systematically. As for the H9N2 virus, which evolved alongside the "Avian-Environment-Human" spreading chain in LPMs from the summer of 2019 to the summer of 2020, its overall efficiency of contact and aerosol transmissibility improved, which might contribute to the increasing probability of human infection. This study indicated that environmental exposure might act as an important source of human infection in LPMs.

Detection and molecular identification of blood parasites in rodents captured from urban areas of southern Sarawak, Malaysian Borneo.

BackgroundRodent species are well known for their potential as hosts and reservoirs for various zoonotic diseases. Studies on blood parasite infection in small mammals focused on urban cities in Peninsular Malaysia and have been conducted over the years. In contrast, there are information gaps related to molecular detection of blood parasites in urban areas of Sarawak that are associated with veterinary importance and zoonotic spillover potential. Increasing prevalence and transmission of blood parasite diseases is the most crucial public health issue, particularly in developing urban areas of Sarawak. Therefore, molecular identification studies were performed to determine and identify the blood parasites infecting rodents.MethodsA total of 40 rodent blood samples were analysed for blood parasite infection and a combined approach using polymerase chain reaction‐based technique, and traditional microscopic examination (blood smear test) was conducted. 18s rRNA (Plasmodium spp.) and cytochrome b (Hepatocystis spp.) gene marker were used to identify the blood parasites.ResultsNote that 67.5% (n = 27) blood samples were tested negative for blood parasites, while 32.5% (n = 13) blood samples collected were infected with at least one protozoan parasite. Out of 13 samples, 69.2% (n = 9) were detected with Hepatocystis sp., while 15.4% (n = 2) were positive with Hepatozoon ophisauri. Two individuals had multiple infections from both species. No Plasmodium spp. have been detected throughout this study using universal primer (targeted Plasmodium spp.); however, different parasite species which were H. ophisauri were detected.ConclusionAlthough there is no evidence of human infection from H. ophisauri and Hepatocystis sp. detected from the study, the data show the host species are heavily infected, and the information is essential for future prevention of zoonotic outbreaks and surveillance programmes. Therefore, it is suggested that the surveillance programmes should be incorporated in targeted areas with a high risk of disease emergence.

Amino acid sites related to the PB2 subunits of IDV affect polymerase activity

BackgroundIn 2011, a new influenza virus, named Influenza D Virus (IDV), was isolated from pigs, and then cattle, presenting influenza-like symptoms. IDV is one of the causative agents of Bovine Respiratory Disease (BRD), which causes high morbidity and mortality in feedlot cattle worldwide. To date, the molecular mechanisms of IDV pathogenicity are unknown. Recent IDV outbreaks in cattle, along with serological and genetic evidence of IDV infection in humans, have raised concerns regarding the zoonotic potential of this virus. Influenza virus polymerase is a determining factor of viral pathogenicity to mammals.MethodsHere we take a prospective approach to this question by creating a random mutation library about PB2 subunit of the IDV viral polymerase to test which amino acid point mutations will increase viral polymerase activity, leading to increased pathogenicity of the virus.ResultsOur work shows some exact sites that could affect polymerase activities in influenza D viruses. For example, two single-site mutations, PB2-D533S and PB2-G603Y, can independently increase polymerase activity. The PB2-D533S mutation alone can increase the polymerase activity by 9.92 times, while the PB2-G603Y mutation increments the activity by 8.22 times.ConclusionTaken together, our findings provide important insight into IDV replication fitness mediated by the PB2 protein, increasing our understanding of IDV replication and pathogenicity and facilitating future studies.

Serological Evidence of Human Infection with Coxiella burnetii after Occupational Exposure to Aborting Cattle.

Cattle are broadly deemed a source of Coxiella burnetii; however, evidence reinforcing their role in human infection is scarce. Most published human Q fever outbreaks relate to exposure to small ruminants, notably goats. Anti-phase II C. burnetii IgG and IgM were measured by indirect fluorescent antibody tests in 27 farm and veterinary diagnostic laboratory workers to ascertain whether occupational exposure to cattle aborting due to C. burnetii was the probable source of exposure. Four serological profiles were identified on the basis of anti-phase II IgG and IgM titres. Profile 1, characterised by high IgM levels and concurrent, lower IgG titres (3/27; 11.1%); Profile 2, with both isotypes with IgG titres higher than IgM (2/27; 7.4%); Profile 3 with only IgG phase II (5/27; 18.5%); and Profile 4, in which neither IgM nor IgG were detected (17/27; 63.0%). Profiles 1 and 2 are suggestive of recent C. burnetii exposure, most likely 2.5–4.5 months before testing and, hence, during the window of exposure to the bovine abortions. Profile 3 suggested C. burnetii exposure that most likely predated the window of exposure to aborting cattle, while Profile 4 represented seronegative individuals and, hence, likely uninfected. This study formally linked human Q fever to exposure to C. burnetii infected cattle as a specific occupational hazard for farm and laboratory workers handling bovine aborted material.

First Detection of the West Nile Virus Koutango Lineage in Sandflies in Niger.

West Nile virus (WNV), belonging to the Flaviviridae family, causes a mosquito-borne disease and shows great genetic diversity, with at least eight different lineages. The Koutango lineage of WNV (WN-KOUTV), mostly associated with ticks and rodents in the wild, is exclusively present in Africa and shows evidence of infection in humans and high virulence in mice. In 2016, in a context of Rift Valley fever (RVF) outbreak in Niger, mosquitoes, biting midges and sandflies were collected for arbovirus isolation using cell culture, immunofluorescence and RT-PCR assays. Whole genome sequencing and in vivo replication studies using mice were later conducted on positive samples. The WN-KOUTV strain was detected in a sandfly pool. The sequence analyses and replication studies confirmed that this strain belonged to the WN-KOUTV lineage and caused 100% mortality of mice. Further studies should be done to assess what genetic traits of WN-KOUTV influence this very high virulence in mice. In addition, given the risk of WN-KOUTV to infect humans, the possibility of multiple vectors as well as birds as reservoirs of WNV, to spread the virus beyond Africa, and the increasing threats of flavivirus infections in the world, it is important to understand the potential of WN-KOUTV to emerge.

Molecular and morphometric identification of Trypanosoma (Megatrypanum) minasense in blood samples of marmosets (Callithrix: Callithrichidae) from the city of Rio de Janeiro, Brazil.

Callithrix jacchus and C. penicillata marmosets are invasive to the state of Rio de Janeiro, Brazil, threatening the native and vulnerable C. aurita. Both invasive species can be hosts of Trypanosoma cruzi, T. minasense, T. rangeli and T. devei. We aim to investigate the occurrence of trypanosomatids in Callithrix sp. from Jardim Botânico do Rio de Janeiro, located in a central and populous area of the city. Fifteen marmosets were captured. Blood samples were collected for light microscopy and molecular genetics analysis. Parasites morphometric values were evaluated for species identification. DNA was extracted from blood samples by phenol-chloroform method, for partial amplification of the 18S rRNA gene. PCR products were sequenced and aligned using BLAST®. A maximum likelihood phylogenetic tree was constructed to analyze the proximity between the observed sequences. By light microscopy, trypomastigotes were detected in five of the fifteen marmosets. Morphometric measurements and size polymorphism corresponded to those previously described for T. minasense. The DNA sequences of approximately 600 base pairs of the 18S rRNA gene were obtained for three samples with 99% identity with T. minasense sequence, forming a cluster in the phylogenetic tree and corroborating morphometric analysis. Trypanosoma minasense is a highly specific parasite to non-human primates considered as non-pathogenic. There is no evidence of infection in humans and these parasite findings from invasive marmosets do not support additional risks for the native species.

Sarcocystis spp. in Romanian Slaughtered Cattle: Molecular Characterization and Epidemiological Significance of the Findings.

Species of the genus Sarcocystis are recognized as protozoan parasites infecting a wide range of animals, including humans. This study aimed to provide data on the occurrence, genetic characterization, and epidemiological significance of Sarcocystis spp. in cattle destined for human consumption in Romania. A total of 117 heart samples from slaughtered cattle in three southwestern Romanian counties (Dolj, Timiș, and Gorj) were analyzed in order to detect sarcocysts, using fresh examination microscopic techniques. Subsequently, the isolated sarcocysts and/or cyst fragments (5–15 per sample) from each infected animal were molecularly characterized. Overall, 17.9% (21/117) of the tested animals were found to be Sarcocystis spp. positive by microscopy. Genetic characterization of Sarcocystis spp. isolates, based on sequence analysis of the 18S rRNA gene, showed the presence of a single species, namely S. cruzi. No correlation was found (p > 0.05) between S. cruzi infection and the origin, age, breed, and gender of cattle, but the grazing farming system was positively associated (p=0.031) with the pathogen prevalence and can be considered a risk factor (OR = 3.6) in acquiring infection. To evaluate the possible public health risk, further investigation focused on the processing of other Sarcocystis-specific tissue matrices and evidence of human infections is recommended. This is the first study of bovine Sarcocystis infection in Romania.

Global epidemiology of Zika and Chikungunya virus human infections

Zika virus was discovered in 1947. The first reported case of Zika fever was in a sentinel rhesus monkey in Uganda in 1947, while the first human cases were reported in Nigeria in 1954. Since the first evidence of human infection, Zika was active in several countries in Africa and Asia, as sporadic cases and serological evidence of Zika human infections have been demonstrated in several reports. The outbreak of Zika in Yap Island in 2007 is considered the first emergency of this infection. Since then Zika has spread worldwide with a large ongoing epidemic in South and Central America. A huge concern nowadays is about the relationship between Zika infection and microcephaly and about the sexual transmission of the virus. The first identified outbreak of Chikungunya human infection, with an incidence estimated at 23%, was reported from July 1952 to March 1953 in the Southern Province of the current Tanzania. Since then Chikungunya circulated mainly in continental Africa with limited outbreaks. The virus started to spread east bound involving most of the areas surroundings the Indian Ocean. In 2004/2005 a large outbreak developed in La Reunion a French territory in the Indian Ocean: from this point Chikungunya spread to India and from there, due a viraemic traveller returning from Kerala, to Italy where in the summer of 2007 the first outbreak with local viral transmission in a temperate climate zone occurred. In the following years Chikungunya moved to the Caribbean and South America. Recently also the USA experienced the spread of this virus and a limited outbreak based again on local spreading occurred in the French Department of Var, in August 2017.

The Global Threat of Animal Influenza Viruses of Zoonotic Concern: Then and Now.

Animal influenza viruses can reassort or mutate to infect and spread sustainably among people and cause a devastating worldwide pandemic. Since the first evidence of human infection with an animal influenza virus, in 1958, 16 different novel, zoonotic influenza A virus subtype groups in 29 countries, Taiwan, and Hong Kong have caused human infections, with differing severity and frequency. The frequency of novel influenza virus detection is increasing, and human infections with influenza A(H5N1) and A(H7N9) viruses are now annual seasonal occurrences in Asia. The study of the epidemiology and virology of animal influenza viruses is key to understanding pandemic risk and informing preparedness. This supplement brings together select recent articles that look at the risk of emergence and transmission of and approaches to prevent novel influenza virus infections.

Evidence of human infection by a new mammarenavirus endemic to Southeastern Asia.

Southeastern Asia is a recognised hotspot for emerging infectious diseases, many of which have an animal origin. Mammarenavirus infections contribute significantly to the human disease burden in both Africa and the Americas, but little data exists for Asia. To date only two mammarenaviruses, the widely spread lymphocytic choriomeningitis virus and the recently described Wēnzhōu virus have been identified in this region, but the zoonotic impact in Asia remains unknown. Here we report the presence of a novel mammarenavirus and of a genetic variant of the Wēnzhōu virus and provide evidence of mammarenavirus-associated human infection in Asia. The association of these viruses with widely distributed mammals of diverse species, commonly found in human dwellings and in peridomestic habitats, illustrates the potential for widespread zoonotic transmission and adds to the known aetiologies of infectious diseases for this region.

Little evidence of human infection with equine influenza during the 2007 epizootic, Queensland, Australia

BackgroundEquine influenza virus (EIV) is considered enzootic in Europe (except Iceland), Asia, North Africa, and North and South America. When EIV outbreaks occur they may severely impact the equine and tourist industries. Australia faced its first EIV outbreak beginning in August of 2007. The outbreak was concentrated in New South Wales and Queensland, with more than 1400 confirmed EIV infections in horses during the first month. Rapid response from the equine industry and the federal government was successful and Australia was declared free from EIV by the end of 2007. ObjectivesThis cross-sectional study was designed to examine associations between exposure to EIV-infected horses and evidence of EIV infection in humans. Study designEmploying informed consent, between October 2007 and April 2008, 100 subjects (89 with horse exposures and 11 non-exposed) were enrolled during equine events and at the University of the Sunshine Coast. All subjects provided a blood sample and were asked to complete an online questionnaire including health history, animal exposure and demographic information. Sera samples were tested for the presence of antibodies against two H3N8 EIV strains using microneutralization, hemagglutination inhibition, and enzyme-linked lectin assays. ResultsEvidence for H3N8 infection was sparse, with only 9 study participants having any indication of H3N8 infection and the seroreactivity seen was low and easily explained by cross-reactions against human influenza strains or vaccines. ConclusionsThese data provide little evidence to support the premise that EIV infections occurred among humans exposed to EIV-infected horses during the 2007 Australian epizootic.

The infectivity of pandemic 2009 H1N1 and avian influenza viruses for pigs: an assessment byex vivorespiratory tract organ culture*

Background Pigs are thought to act as intermediate hosts in the ecology of influenza viruses of both avian and human origin. The recent development of procedures for pig ex vivo respiratory organ explants has provided new tools for the assessment of influenza virus infection in pigs. Objectives To use pig ex vivo organ explants to assess the susceptibility of pigs to infection with contemporary viruses, for which there is evidence of human infection and that are thought to pose the greatest threat to pig and human populations. Methods Pig tracheal, bronchi and lung ex vivo organ explants were infected with both highly pathogenic and low pathogenic avian influenza (AI) virus and the pandemic H1N1 [A(H1N1)pdm/09] virus. Successful infection of explants was detected using a positive‐sense RNA real‐time RT‐PCR assay and anti‐nucleoprotein immunohistochemistry. The distribution of cell‐surface α2‐3‐ and α2‐6‐linked sialic acid receptors, the avian‐ and mammalian influenza A virus–preferred host receptors, respectively, was also characterised for the ex vivo organ cultures and uninfected pig material following necropsy. Results The α2‐3 and α2‐6 sialic acid receptor staining on tracheal, bronchi and lung organ explant sections showed similar distributions to those seen for pig tissue following necropsy. While the pig ex vivo organ cultures were susceptible to nearly all viruses tested, lower levels of virus were detected in trachea and bronchi after infection. Conclusion These results confirm that pigs are susceptible to contemporary viruses that may threaten both veterinary and human health and contribute to the ecology of influenza A viruses.

Neonatal Gene Therapy of Glycogen Storage Disease Type Ia Using a Feline Immunodeficiency Virus–based Vector

Glycogen storage disease type Ia (GSD-Ia), also known as von Gierke disease, is caused by a deficiency of glucose-6-phosphatase-alpha (G6Pase), a key enzyme in glucose homeostasis. From birth, affected individuals cannot maintain normal blood glucose levels and suffer from a variety of metabolic disorders, leading to life-threatening complications. Gene therapy has been proposed as a possible option for treatment of this illness. Vectors have been constructed from feline immunodeficiency virus (FIV), a nonprimate lentivirus, because the wild-type virus does not cause disease in humans. Previously, we have shown that these vectors are capable of integrating stably into hepatocyte cell lines and adult murine livers and lead to long-term transgene expression. In the current work, we have assessed the ability to attenuate disease symptoms in a murine model of GSD-Ia. Single administration of FIV vectors containing the human G6Pase gene to G6Pase-alpha(-/-) mice did not change the biochemical and pathological phenotype. However, a double neonatal administration protocol led to normalized blood glucose levels, significantly extended survival, improved body weight, and decreased accumulation of liver glycogen associated with the disease. This approach shows a promising paradigm for treating GSD-Ia patients early in life thereby avoiding long-term consequences.

Epidemiology, control and surveillance of Chagas disease: 100 years after its discovery

Chagas disease originated millions of years ago as an enzootic infection of wild animals and began to be transmitted to humans as an anthropozoonosis when man invaded wild ecotopes. While evidence of human infection has been found in mummies up to 9,000 years old, endemic Chagas disease became established as a zoonosis only in the last 200-300 years, as triatomines adapted to domestic environments. It is estimated that 15-16 million people are infected with Trypanosoma cruzi in Latin America, and 75-90 million are exposed to infection. Control of Chagas disease must be undertaken by interrupting its transmission by vectors and blood transfusions, improving housing and areas surrounding dwellings, providing sanitation education for exposed populations and treating acute and recently infected chronic cases. These measures should be complemented by surveillance and primary, secondary and tertiary care.

Delinquent Mortgages, Neglected Swimming Pools, and West Nile Virus, California

We thank Goodman and Buehler for their comments about our recent article drawing attention to linkages among neglected swimming pools, vector mosquito production, and West Nile virus (WNV) transmission (1). We agree with their comment that our “study could not directly assess the putative link between disease and exposures to WNV-infected mosquitoes that had bred in abandoned swimming pools in California.” However, outbreaks of pathogens with complicated transmission cycles rarely afford isolation of any one factor for analysis. Notably, an update of events in Kern County during 2008 may support our previous conclusions. As in 2007, Kern County experienced continued drought conditions in 2008, and mosquito production was again confined largely to urban sources, including swimming pools. Avian abundance was low, and seroprevalence for WNV among selected bird species was similar to seroprevalence rates for 2007 (i.e., 7.8% of 192 house finches, 5.6% of 90 house sparrows, and 41.2% of 68 western scrub-jays were seropositive in 2007). However, early in the spring of 2008, unlike in 2007, the Kern Mosquito and Vector Control District (MVCD) commenced aerial surveys, reassigned rural field crews to treat swimming pools (and other urban water sources), and immediately conducted ground-based adulticiding when surveillance detected enzootic activity. This aggressive approach resulted in 2,182 swimming pools treated (a 255% increase over the number treated in 2007), reduced enzootic transmission (i.e., 5% of 192 dead birds, 17 serum samples from 90 sentinel chickens, and 1% of 598 mosquito pools positive for WNV), and almost no evidence of human infection (only 1 case reported in October). Intervention by the Kern MVCD, coupled with continuing severe drought conditions that eliminated natural and agricultural-related mosquito production sites, effectively eliminated WNV epidemic transmission that had persisted during the 4 previous years (2).

Evidence of Infection in Humans with Rickettsia typhi and Rickettsia felis in Catalonia in the Northeast of Spain

Murine typhus is a cause of fever of intermediate duration in the south of Spain, where antibodies against Rickettsia typhi and Rickettsia felis were observed in humans. This study presents the first report from the northeast of Spain. Human serum samples were tested by serological test. R. typhi and R. felis seroprevalences were 8.8% and 3.2%, respectively.

Ornithodoros moubata, a Soft Tick Vector for Rickettsia in East Africa?

Omithodoros moubata complex (Argasidae) ticks collected from human dwellings in central Tanzania were found to carry a novel rickettsial species that clustered among the spotted fever group. Although no evidence of human infection was evident, these ticks feed primarily on man, thus providing opportunity for zoonotic infection.

Serological evidence of human infection with rickettsial strain Bar29 in Catalonia, northeastern Spain

Mediterranean spotted fever (MSF) is an endemic disease in Catalonia, northeastern Spain. The causative agent is Rickettsia conorii, which is transmitted by the dog tick Rhipicephalus sanguineus in the Mediterranean area [1, 2]. However, it is strongly suspected that another spotted fever group (SFG) rickettsial strain could be implicated in some cases of MSF diagnosed in Catalonia [3, 4]. In 1990, Mtu1 and Mtu5 were isolated from Rhipicephalus turanicus ticks collected in the south of France. Both were new serotypes related to the SFG rickettsiae [5]. Mtu1 was named Rickettsia massiliae and proposed as a new SFG Rickettsia species [6]. Strains related to R. massiliae have been identified throughout the world [7]. In Catalonia, a new SFG rickettsial strain (Bar29) was isolated by our group in 1996 from R. sanguineus; it is identical to the Mtu5 strain and closely related to R. massiliae [3]. R. massiliae Bar29 belongs to the R. massiliae group of SFG that includes R. massiliae, Rickettsia aeschlimannii, Rickettsia montanensis and Rickettsia rhipicephali [7]. A previous study we conducted using sera from Catalonian patients suggested R. massiliae Bar29 could be implicated in cases of MSF diagnosed in our region [4]. Currently, R. massiliae and R. aeschlimannii are recognized as human pathogens [7, 8]. The aim of the study presented here was to determine the seroprevalence of R. massiliae Bar29 in a representative population of Catalonia and to identify possible risk factors for infection. The study was performed in a predominantly urban area near the coast in northeastern Spain. Between September 1993 and January 1994, 211 subjects who had received attention at Sabadell’s Hospital were chosen to participate in a study searching for antibodies to R. conorii and Borrelia burgdorferi. The sample size had been estimated taking into account overall prevalences of 11 and 3% of antibodies to R. conorii and B. burgdorferi, respectively (given an alpha error of 0.05). The sample included adults undergoing minor surgery and children who visited the Pediatric Emergency Service. Taking into account the actual population, the study population was stratified by age and residential area. After informed consent was obtained, a serum sample was collected. Age, sex, demographic area, occupation, contact with dogs, contact with wild animals, contact with farm animals, and history of MSF were surveyed. One milliliter of blood was collected in tubes containing heparin. The sample of heparinized blood was sedimented and the supernatant (0.5 ml) was collected and stored at −80°C. Human sera were evaluated using an indirect immunofluorescence assay (IFA) for IgG antibodies [9]. Antigen was obtained from the R. massiliae Bar29 strain previously isolated from ticks and cultured in our laboratory [3]. Titers ≥1/40 were considered positive. Statistical analysis was performed using the chi-square test, Fisher's Eur J Clin Microbiol Infect Dis (2006) 25:541–543 DOI 10.1007/s10096-006-0176-1

Comparative macrorestriction and RFLP analysis of Mycobacterium avium subsp. avium and Mycobacterium avium subsp. hominissuis isolates from man, pig, and cattle

In Germany, tuberculous lesions in slaughtered pigs due to infection with members of the Mycobacterium avium complex are increasingly reported. Contaminated food originating from pig or other livestock is discussed as potential source of human infection. M. avium isolates from man ( n = 45), pig ( n = 29), and cattle ( n = 13) were characterised by restriction fragment length polymorphism (RFLP) with respect to insertion sequences IS 1245 and IS 901 as well as by XbaI-based pulsed-field gel electrophoresis (PFGE) and the results were compared by computer cluster correlation analysis, to determine potential sources of infection in man. By PCR, 55% of animal isolates was identified as M. avium subsp. avium, and 45% as M. a. hominissuis. All human isolates belonged to M. a. hominissuis. IS 1245-RFLP and PFGE resulted in two distinct main groupings reflecting the two subspecies, and dividing the isolates into several subgroups. Animal isolates of M. a. hominissuis were widely distributed within the subgroups of human isolates. M. a. avium isolates, further discriminated by IS 901-RFLP, formed host-associated subgroups for animals. Comparison of RFLP patterns with those of PFGE resulted in different subgroups as well as different pairs of isolates with high similarities. Only two isolates exhibited identical patterns by both methods. In general, results of both methods support the possibility that M. a. hominissuis isolates from livestock represent a source of infection for man, probably by common environmental reservoirs. There was no evidence of human infections caused by M. a. avium in Germany.