Melissa Miller

Melissa Miller
California Department of Fish and Wildlife | DFG · Office of Spill Prevention and Response

DVM, PhD, MS
Disease outbreak investigation and research centered on emerging infectious disease, land-sea pollution, One Health

About

205
Publications
51,145
Reads
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6,007
Citations
Citations since 2017
37 Research Items
2552 Citations
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Introduction
Melissa’s diagnostic focus centers on health and conservation of marine wildlife, especially threatened and endangered species and animals that are most vulnerable to oil spills. Her areas of research specialization include One Health, emerging infectious disease, parasitology, land-sea pollution, and marine and freshwater biotoxins.
Additional affiliations
June 2002 - August 2004
University of California, Davis
Position
  • Wildlife Veterinarian
Description
  • This is the same job tasking and work location as my current position. I have worked in this position since 1999 as a UCD Graduate student, UCD Staff Veterinarian and CDFW Veterinarian Specialist. I maintain a non-salaried appointment with the UCD-WHC.
January 1999 - present
California Department of Fish and Wildlife
Position
  • Wildlife Veterinarian Specialist/ Pathologist
Description
  • Conduct complex environmental health research, present findings and prepare and submit scientific publications & grant proposals. Maintain non-salaried staff appointments at UCD and UCSC.
June 1997 - June 1999
University of California, Davis
Position
  • Instructor in Anatomic Pathology: School of Veterinary Medicine
Education
June 1998 - June 2002
University of California, Davis School of Veterinary Medicine
Field of study
  • Anatomic Pathology (Wildlife Emphasis)
August 1995 - September 1999
University of California, Davis School of Veterinary Medicine
Field of study
  • Anatomic Pathology
July 1994 - July 1995
North Carolina State University School of Veterinary Medicine
Field of study
  • Small Animal Medicine and Surgery Externship

Publications

Publications (205)
Article
Full-text available
Acanthocephalan peritonitis (AP; trans-intestinal migration of acanthocephalan parasites into the peritoneal cavity resulting in severe peritonitis), is a common cause of mortality in southern sea otters (Enhydra lutris nereis). Although Profilicollis spp. acanthocephalans have been implicated in these infections, the species causing AP has been an...
Article
Full-text available
From February 2020 to March 2022, four southern sea otters (Enhydra lutris nereis) stranded in California with severe protozoal steatitis and systemic toxoplasmosis. Three of the infected otters stranded within 26 km of each other, and all four animals died during periods of increased rainfall-driven surface water runoff. High parasite burdens were...
Article
Full-text available
Nasopulmonary mites (NPMs) of the family Halarachnidae are obligate endoparasites that colonize the respiratory tracts of mammals. NPMs damage surface epithelium resulting in mucosal irritation, respiratory illness, and secondary infection, yet the role of NPMs in facilitating pathogen invasion or dissemination between hosts remains unclear. Using...
Article
Southern sea otters (SSO: Enhydra lutris nereis) are a federally-listed threatened subspecies found almost exclusively in California, USA. Despite their zoonotic potential and lack of host specificity, K. pneumoniae and Klebsiella spp. have largely unknown epizootiology in SSOs. Klebsiella pneumoniae is occasionally isolated at necropsy, but not fr...
Article
Southern sea otter (Enhydra lutris nereis) population recovery is influenced by a variety of factors, including predation, biotoxin exposure, infectious disease, oil spills, habitat degradation, and resource limitation. This population has also experienced a significant genetic bottleneck, resulting in low genetic diversity. We investigated how two...
Article
Full-text available
Sea otters (Enhydra lutris) demonstrate rapid, accurate tactile abilities using their paws and facial vibrissae. Anatomical investigations of neural organization in the vibrissal bed and somatosensory cortex coincide with measured sensitivity, but no studies describe sensory receptors in the paws or other regions of glabrous (i.e., hairless) skin....
Article
Full-text available
Mites from the family Halarachnidae (Oudemans, 1906) are obligate endoparasites that colonize the respiratory tracts of free-living and captive marine mammals. Infestations can range from mild to severe and result in respiratory tract irritation or impairment. Nasopulmonary acariasis was determined to be a contributing cause of death among several...
Article
Full-text available
Objective: To compare serum cardiac troponin I (cTnI) concentrations between sea otters with and without cardiomyopathy and describe 2 cases of cardiomyopathy with different etiologies. Animals: 25 free-ranging southern sea otters (Enhydra lutris nereis) with (n = 14; cases) and without (11; controls) cardiomyopathy and 17 healthy managed southe...
Article
Full-text available
The marine biotoxin domoic acid (DA) is an analog of the neurotransmitter glutamate that exerts potent excitatory activity in the brain, heart, and other tissues. Produced by the diatom Pseudo-nitzschia spp., DA accumulates in marine invertebrates, fish, and sediment. Southern sea otters (Enhydra lutris nereis) feed primarily on invertebrates, incl...
Preprint
Full-text available
How virulent protozoal pathogens capable of causing overt disease are maintained in nature is an important paradigm of eukaryotic pathogenesis. Here we used population genetics and molecular methods to study the evolution and emergence of a marine invasion of new genetic variants of Toxoplasma gondii , referred collectively as Type X (HG12). 53 Tox...
Article
Background: Southern sea otters (Enhydra lutris nereis) rely on intact pelage for thermoregulation, and thus clinically significant demodicosis and associated alopecia can cause morbidity and death. Hypothesis/objectives: This study aimed to describe lesions associated with follicular Demodex sp. infestation, estimate the prevalence and intensit...
Article
Full-text available
Harmful algal blooms produce toxins that bioaccumulate in the food web and adversely affect humans, animals, and entire marine ecosystems. Blooms of the diatom Pseudo-nitzschia can produce domoic acid (DA), a toxin that most commonly causes neurological disease in endothermic animals, with cardiovascular effects that were first recognized in southe...
Article
Full-text available
We compiled findings from 15 years (1998-2012) of southern sea otter (Enhydra lutris nereis) necropsies, incorporating data from 560 animals. Sensitive diagnostic tests were used to detect biotoxins, bacteria, parasites and fungi. Methods to classify primary and contributing causes of death (COD) and sequelae utilized an updated understanding of he...
Article
Full-text available
Southern sea otters (Enhydra lutris nereis) are threatened marine mustelids that commonly have gastric ulcers with secondary hemorrhage (melena) as a contributing cause of death. Although Helicobacter spp. infections are known to cause gastric ulcers and gastritis in humans and ferrets, it is unknown if the sea otter bacterium, H. enhydrae sp. nov....
Article
Full-text available
Capillaria hepatica is a globally distributed zoonotic nematode parasite that most commonly infects feral and native rats. Soil contact, pica, and living in close proximity to rat populations are risk factors for human infection. Larval nematodes and eggs that were morphologically consistent with C. hepatica were observed microscopically in livers...
Article
Full-text available
Sarcocystis neurona was recognised as an important cause of mortality in southern sea otters (Enhydra lutris nereis) after an outbreak in April 2004 and has since been detected in many marine mammal species in the Northeast Pacific Ocean. Risk of S. neurona exposure in sea otters is associated with consumption of clams and soft-sediment prey and is...
Poster
Southern sea otters (SSO; Enhyra lutris nereis) are a federally-listed threatened population and recovery has been hindered, in part, by infectious diseases. Klebsiella pneumoniae and Erysipelothrix rhusiopathiae are two bacterial pathogens implicated as rare, but primary or contributing causes of mortality in SSO. Both bacteria cause illness in ot...
Article
Full-text available
Why some Toxoplasma gondii-infected southern sea otters (Enhydra lutris nereis) develop fatal toxoplasmosis while others have incidental or mild chronic infections has long puzzled the scientific community. We assessed robust datasets on T. gondii molecular characterization in relation to detailed necropsy and histopathology results to evaluate whe...
Article
Five Mycoplasma strains have been isolated from the oropharynx of southern sea otters (Enhydra lutris nereis) from the Central California Coast, USA. These strains were phenotypically and genetically characterized and compared to other established Mycoplasma species. All five strains hydrolysed arginine but not urea, but did not produce acid from g...
Article
Full-text available
Parasitism, particularly in concert with other sublethal stressors, may play an important, yet underappreciated role in morbidity and mortality of threatened species. During necropsy of southern sea otters (Enhydra lutra nereis) from California submitted to the Marine Wildlife Veterinary Care and Research Center's Sea Otter Necropsy Program between...
Article
Full-text available
Pathogens entering the marine environment as pollutants exhibit a spatial signature driven by their transport mechanisms. The sea otter (Enhydra lutris), a marine animal which lives much of its life within sight of land, presents a unique opportunity to understand land–sea pathogen transmission. Using a dataset on Toxoplasma gondii prevalence acros...
Article
Microcystins/Nodularins (MCs/NODs) are potent hepatotoxic cyanotoxins produced by harmful algal blooms (HABs) that occur frequently in the upper basin of the St. Johns River (SJR), Jacksonville, FL, USA. Areas downstream of bloom locations provide critical habitat for an estuarine population of bottlenose dolphins (Tursiops truncatus). Since 2010,...
Article
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Conservation genetic techniques and considerations of the evolutionary potential of a species are increasingly being applied to species conservation. For example, effective population size (Ne) estimates are useful for determining the conservation status of species, yet accurate estimates of current Ne remain difficult to obtain. The effective popu...
Article
Due to increased concerns regarding fecal pollution at marine recreational beaches, daily relative dog abundance and fecal density were estimated on an intensively managed (Beach 1) and a minimally managed (Beach 2) dog beach in Monterey County, California. Fecal loading and factors predictive of fecal deposition also were assessed. After standardi...
Article
We present a novel case of an intestinal cestode infection in a southern sea otter (Enhydra lutris nereis). The cestode species Diplogonoporus tetrapterus was confirmed genetically. Stable isotope analysis of whiskers collected from the sea otter did not confirm the consumption of fish as the route of exposure.
Article
There are approximately 3,000 southern sea otters (Enhydra lutris nereis) in the nearshore environment along the California coast, and the species is classified as Threatened under the Endangered Species Act. We tested sera from 661 necropsied southern sea otters sampled from 1997 to 2015 to determine overall exposure to influenza A viruses (IAVs)...
Article
Full-text available
Over the past century, the southern sea otter (SSO; Enhydra lutris nereis) population has been slowly recovering from near extinction due to overharvest. The SSO is a threatened species under federal law and a fully protected species under California law. Through a multiagency collaborative program, stranded animals are rehabilitated and released,...
Article
We characterize Brucella infection in a wild southern sea otter ( Enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. This otter stranded twice along the central California coast over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surg...
Technical Report
Full-text available
The Brown Pelican Mortality Working Group was formed in 2013 under Federal financial assistance from the U.S. Fish and Wildlife Service’s CDFA Program under the authority of the Endangered Species Act of 1973. This group aimed to establish a framework for tracking issues of concern regarding the health and viability of the California Brown Pelican...
Article
Full-text available
Histologic lesions incidental to the cause of death were observed in the adrenal glands of 17 subadult and adult leatherback sea turtles (Dermochelys coriacea) found dead or moribund on or near shore in North America. Round bodies, 250–300 lm in diameter composed of an outer capsule and large multinucleated cells surrounding a central mass of acell...
Article
Seven sea otters received a single subcutaneous dose of cefovecin at 8 mg/kg body weight. Plasma samples were collected at predetermined time points and assayed for total cefovecin concentrations using ultra-performance liquid chromatography and tandem mass spectrometry. The mean (±SD) noncompartmental pharmacokinetic indices were as follows: CMax...
Article
Full-text available
People, domestic animals, and wildlife are all exposed to numerous environmental threats, including harmful algal blooms (HABs). However, because animals exhibit wide variations in diet, land use and biology, they are often more frequently or heavily exposed to HAB toxins than are people occupying the same habitat, making them sentinels for human e...
Article
Full-text available
Sea otters (Enhydra lutris) have exceptionally high energetic requirements, which nearly double during lactation and pup care. Thus, females are extremely vulnerable to caloric insufficiency. Despite a number of compensatory strategies, the metabolic challenge of reproduction culminates in numerous maternal deaths annually. Massive depletion of ene...
Article
Full-text available
A total of 31 sea otters Enhydra lutris nereis found dead or moribund (and then euthanized) were necropsied in California, USA. Stomach biopsies were collected and transected with equal portions frozen or placed in formalin and analyzed histologically and screened for Helicobacter spp. in gastric tissue. Helicobacter spp. were isolated from 9 sea o...
Conference Paper
The Southern Sea Otter (Enhydra lutris nereis) was nearly extirpated during the late 19th century as a result of the fur trade. Following protection by the US federal government, southern sea otter populations have rebounded from a small remnant population near Big Sur California. Tremendous effort has gone into monitoring the health and population...
Article
Full-text available
Recent studies have implicated beta-hemolytic streptococci as opportunistic pathogens of marine mammals, including southern sea otters (Enhydra lutris nereis), but little is known about their prevalence or pathophysiology. Herein, we focus on risk factors for sea otter infection by a single beta-hemolytic streptococcal species, Streptococcus phocae...
Article
Full-text available
Toxoplasma gondii and Sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. Close monitoring of threatened southern sea otters (Enhydra lutris nereis) in California allowed for the diagnosis of dual transplacental transmission of T. gondii and S....
Research
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Summarized findings from a multi-year, cross-collaborative study on fecal pathogen pollution and potential methods for mitigation in California.
Article
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The southern sea otter (Enhydra lutris nereis) is a threatened marine sentinel. During postmortem investigations of stranded sea otters from 2004 to 2013 in California, USA, papillomas were detected in the oral cavity of at least seven otters via necropsy and histopathology. Next-generation sequencing of viral particles purified from a single papil...
Article
Full-text available
A wide range of systemic mycoses have been reported from captive and wild marine mammals from North America. Examples include regionally endemic pathogens such as Coccidioides and Blastomyces spp., and novel pathogens like Cryptococcus gattii, which appear may have been introduced to North America by humans. Stranding and necropsy data were analyze...
Article
Abstract Since 2002, an increased number of northern sea otters (Enhydra lutris kenyoni) from southcentral Alaska have been reported to be dying due to endocarditis and/or septicemia with infection by Streptococcus infantarius subsp. coli. Bartonella spp. DNA was also detected in northern sea otters as part of mortality investigations during this u...
Article
Full-text available
Leatherback sea turtles are globally distributed and endangered throughout their range. There are limited data available on disease in this species. Initial observations of solitary large intestinal diverticulitis in multiple leatherbacks led to a multi-institutional review of cases. Of 31 subadult and adult turtles for which complete records were...
Article
Full-text available
Background: Environmental transmission of the zoonotic parasite Toxoplasma gondii, which is shed only by felids, poses risks to human and animal health in temperate and tropical ecosystems. Atypical T. gondii genotypes have been linked to severe disease in people and the threatened population of California sea otters. To investigate land-to-sea pa...
Article
Full-text available
Environmental transmission of Toxoplasma gondii, a global zoonotic parasite, adversely impacts human and animal health. Toxoplasma is a significant cause of mortality in threatened Southern sea otters, which serve as sentinels for disease threats to people and animals in coastal environments. As wild and domestic felids are the only recognized host...
Article
Skin biopsies were collected from free-ranging harbor seals (Phoca vitulina richardii) from central California (n = 53). Microscopic examination of hematoxylin and eosin-stained tissue sections revealed the presence of tightly coiled nematode larvae within the ostia of numerous hair follicles of four seals. Parasites were characterized by paired la...
Article
Full-text available
Cyanobacteria (also called blue-green algae) are ubiquitous in aquatic environments. Some species produce potent toxins that can sicken or kill people, domestic animals, and wildlife. Dogs are particularly vulnerable to cyanotoxin poisoning because of their tendency to swim in and drink contaminated water during algal blooms or to ingestalgal mats....
Article
Full-text available
A two and a half year old spayed female Miniature Australian Shepherd presented to a Montana veterinary clinic with acute onset of anorexia, vomiting and depression. Two days prior, the dog was exposed to an algal bloom in a community lake. Within h, the animal became lethargic and anorexic, and progressed to severe depression and vomiting. A compl...
Article
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Constructed wetland systems are used to reduce pollutants and pathogens in wastewater effluent, but comparatively little is known about pathogen transport through natural wetland habitats. Fecal protozoans, including Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii, are waterborne pathogens of humans and animals, which are carried by...
Article
Full-text available
Pulsed-field gel electrophoresis (PFGE) was used to type 128 Streptococcus infantarius subsp. coli isolates from sea otters and mussels. Six SmaI PFGE groups were detected, with one predominant group representing 57% of the isolates collected over a wide geographic region. Several sea otter and mussel isolates were highly related, suggesting that a...
Article
Full-text available
The risk of disease transmission from waterborne protozoa is often dependent on the origin (e.g., domestic animals versus wildlife), overall parasite load in contaminated waterways, and parasite genotype, with infections being linked to runoff or direct deposition of domestic animal and wildlife feces. Fecal samples collected from domestic animals...