Equine amnionitis and fetal loss: mare abortion following experimental exposure to Processionary caterpillars (Ochrogaster lunifer)

Host Specificity in Canopy Nesting Forms of Ochrogaster lunifer: The Larger Children Do Not Care

The 'mother knows best' hypothesis is tested in a species of processionary moth feeding on acacias and eucalypts in Australia. The processionary moth Ochrogaster lunifer (Lepidoptera: Notodontidae; Thaumetopoeinae) is a social caterpillar living in large colonies on a number of tree and shrub species. Five nesting types-canopy, trunk, tree-hugger, hanging, and ground-have been described, and this study deals with canopy nesters on various species of acacias (Acacia spp.) and eucalypts (Eucalyptus spp. and Corymbia spp.). Reciprocal transplant experiments conducted over three years confirm the 'mother knows best' hypothesis, as colonies performed better on the natal host plant than on the recipient ones. Young first instar larvae were less likely to establish on a non-natal host than the mature larvae, and all acacia-sourced canopy egg masses failed to establish on eucalypts. Large larvae were able to establish on transplant hosts. This suggests a strong preference-performance link at what is likely a species level, confirming preliminary results recently published on genetic divergence. Canopy nesting forms also have a lower realised fecundity than the ground nesting form on acacias from the same geographic area, but higher than another canopy nesting form from western Australia. Further observations on ecological and genetic traits are required to draw conclusions about the separation of lineages in the canopy nesting form of O. lunifer, by including populations from other parts of the range for both the herbivore and the host plants.

Infectious Causes of Equine Placentitis and Abortion

A variety of infectious agents including viral, bacterial, and fungal organisms can cause equine abortion and placentitis. Knowledge of normal anatomy and the common pattern distribution of different infectious agents will assist the practitioner in evaluating the fetus and/or placenta, collecting appropriate samples for further testing, and in some cases, forming a presumptive diagnosis. In all cases, it is recommended to confirm the diagnosis with molecular, serologic, or microbiological testing. If a causative agent can be identified, then appropriate biosecurity and vaccination measures can be instituted on the farm.

Causes of equine perinatal mortality

The peripartum period is critical in equine medicine for maintaining healthy mares, and ensuring the delivery of healthy neonatal foals. The field of perinatal mortality in horses is continuously evolving, with several advances being recently made in causes of perinatal fetal and foal loss. This review details the main causes of perinatal loss in horses, through late pregnancy, parturition and the neonatal period. Recent advances in identification of infectious organisms and indicators of survival in neonatal foals will be discussed. Continued advances in reproductive and neonatal medicine will aid improved survival of foals through fewer pregnancy losses, and improved management of high-risk pregnancies and critically ill neonatal foals.

Incidence and causes of pregnancy loss after Day 70 of gestation in Thoroughbreds

BACKGROUND

Pregnancy loss after Day 70 of gestation manifests as abortion, stillbirth or perinatal death. While previous studies have reported the diagnoses of laboratory submissions, none have quantified the incidence and causes of abortions, stillbirths and perinatal mortality at a population level.

OBJECTIVES

To report the incidence and causes of pregnancy loss after Day 70 of gestation in a cohort of Thoroughbreds.

STUDY DESIGN

Retrospective cohort study.

METHODS

Outcomes of Day 70 pregnancies were collected from eight Thoroughbred farms over the 2013-2017 breeding seasons. Stud, veterinary and laboratory records were supplemented with publicly available data. Cause of loss was categorised using custom criteria.

RESULTS

Data were collected on 3,586 pregnancies from 1,802 mares. The incidence risk of a pregnancy failing to produce a live foal at 24 hours post parturition was 7.3% (95% confidence interval (CI) 6.5-8.2, equating to 7.3 cases per 100 Day-70 pregnancies). The incidence of pregnancy loss between Day 70 and 300 of gestation, Day 301-315 and stillbirth/perinatal death was 4.0% (95% CI 3.4-4.7), 0.3% (95% CI 0.2-0.6) and 1.4% (95% CI 1.1-1.9) respectively. Of the pregnancy losses where tissue was available, 61.1% were submitted for post-mortem examination. The incidence risk of loss due to umbilical cord-related pathologies was 1.5% (95% CI 1.1-1.9), 0.4% (95% CI 0.2-0.6) for noninfectious placental disease and 0.3% (95% CI 0.2-0.6) for both infectious placentitis and Equine Herpesvirus infection. No primary diagnosis was made in 11.2% of the cases which underwent full post-mortem examination.

MAIN LIMITATIONS

It was not possible to differentiate between intra-partum stillbirth and early post-partum death.

CONCLUSION

Pregnancy loss after Day 70 of gestation is a significant source of loss in the Thoroughbred with umbilical cord-related pathologies being the most commonly diagnosed cause. Reporting the incidence of pregnancy loss at a population level with clear case definitions will allow for accurate global comparisons.

Movement behaviour of two social urticating caterpillars in opposite hemispheres

BACKGROUND

Investigating movement ecology of organisms has economic, societal, and conservation benefits. Larval movement of insects for example, plays many significant ecological roles, and with the expansion of the human population and development, encounters and conflicts with insects have increased. Urticating caterpillars are a health concern to people and animals, especially when they disperse in a gregarious and synchronised manner in areas frequented by humans. Ochrogaster lunifer and Thaumetopoea pityocampa from the southern and northern hemispheres respectively, are two geographically-isolated species of moth with similar gregarious urticating caterpillars that can outbreak causing defoliation and medical issues.

METHODS

Each year from March to May, O. lunifer and T. pityocampa caterpillars leave their nesting sites and form head-to-tail processions on the ground in search of pupation sites. This pre-pupation procession behaviour and its associated risk of human contact with O. lunifer and T. pityocampa caterpillars were studied and compared in Australia and Italy, respectively. The distance, duration, orientation and response to visible light of the pre-pupation processions were studied in both species to determine general patterns.

RESULTS

In the morning, O. lunifer and T. pityocampa processions travelled on average 40 and 16 m per day from the nest in 153 and 223 min respectively, in search for potential pupation sites. Ochrogaster lunifer pre-pupation processions travelled generally to the north or south when leaving the nest, as was their final orientation to the bivouac/pupation site. Whereas T. pityocampa processions had no preference in orientation. Ochrogaster lunifer and T. pityocampa pre-pupation processions travelled towards the darker and the lighter areas of the environment, respectively. During our observations, 27% of O. lunifer and 44% of T. pityocampa processions had contact with humans driving, cycling or walking.

CONCLUSIONS

The amount of human contact is surprising and alarming, because of the serious health implications they cause to humans and animals. The processionary dispersal on the ground risks further spread of urticating hairs that can be easily detached, and particular during inadvertent contact. Our limited sample size of T. pityocampa processions may benefit from more observations to make conclusive remarks on their pre-pupation behaviour. Understanding the movement behaviour of O. lunifer and T. pityocampa pre-pupation processions around populated areas is crucial for predicting exposure risk and application of management strategies.

Variation in Morphology and Airborne Dispersal of the Urticating Apparatus of Ochrogaster lunifer (Lepidoptera: Notodontidae), an Australian Processionary Caterpillar, and Implications for Livestock and Humans

True setae borne on the abdominal tergites of Ochrogaster lunifer Herrich-Schӓffer caterpillars are the agents of an irritating contact dermatitis, osteomyelitis, ophthalmia, and severe allergic reactions in humans, and are the cause of Equine Amnionitis and Fetal Loss in Australia. The setae are detached and readily dislodge from the integument whereby they disperse throughout the environment. To better understand the true setae of O. lunifer as agents of medical and veterinary concern, we studied their characteristics and distance dispersed. Whereas members of the European Thaumetopoeinae have been widely studied, their southern-hemisphere counterparts such as O. lunifer are not well known despite their harmfulness and known medical and veterinary importance. The caterpillar's investment in true setae increased with age and size, and two distinct size classes co-occurred in setae fields. A previously undescribed morphological type of true seta was found on the first abdominal segment. All true setae were calculated to travel long distances in the air even under light breeze conditions. Our results show there is a high risk of exposure to airborne urticating setae within 100 m of elevated caterpillar activity, and a likely risk of exposure for some kilometers in the direction of the prevailing breeze. This information should be used to inform management strategies in areas where urticating processionary caterpillars are active, and especially during periods of an outbreak.

Processionary Moths and Associated Urtication Risk: Global Change-Driven Effects

Processionary moths carry urticating setae, which cause health problems in humans and other warm-blooded animals. The pine processionary moth Thaumetopoea pityocampa has responded to global change (climate warming and increased global trade) by extending its distribution range. The subfamily Thaumetopoeinae consists of approximately 100 species. An important question is whether other processionary moth species will similarly respond to these specific dimensions of global change and thus introduce health hazards into new areas. We describe, for the first time, how setae are distributed on different life stages (adult, larva) of major groups within the subfamily. Using the available data, we conclude that there is little evidence that processionary moths as a group will behave like T. pityocampa and expand their distributional range. The health problems caused by setae strongly relate to population density, which may, or may not, be connected to global change.

The urticating setae of Ochrogaster lunifer, an Australian processionary caterpillar of veterinary importance

The bag-shelter moth, Ochrogaster lunifer Herrich-Schaffer (Lepidoptera: Notodontidae), is associated with a condition called equine amnionitis and fetal loss (EAFL) on horse farms in Australia. Setal fragments from O. lunifer larvae have been identified in the placentas of experimentally aborted fetuses and their dams, and in clinical abortions. The gregarious larvae build silken nests in which large numbers cohabit over spring, summer and autumn. The final instars disperse to pupation sites in the ground where they overwinter. Field-collected O. lunifer larvae, their nests and nearby soil were examined using light and electron microscopy to identify setae likely to cause EAFL and to determine where and how many were present. Microtrichia, barbed hairs and true setae were found on the exoskeletons of the larvae. True setae matching the majority of setal fragments described from equine tissue were found on third to eighth instar larvae or exuviae. The number of true setae increased with the age of the larva; eighth instars carried around 2.0-2.5 million true setae. The exuvia of the pre-pupal instar was incorporated into the pupal chamber. The major sources of setae are likely to be nests, dispersing pre-pupal larvae and their exuviae, and pupal chambers.

Population Explosions of Tiger Moth Lead to Lepidopterism Mimicking Infectious Fever Outbreaks

Lepidopterism is a disease caused by the urticating scales and toxic fluids of adult moths, butterflies or its caterpillars. The resulting cutaneous eruptions and systemic problems progress to clinical complications sometimes leading to death. High incidence of fever epidemics were associated with massive outbreaks of tiger moth Asota caricae adult populations during monsoon in Kerala, India. A significant number of monsoon related fever characteristic to lepidopterism was erroneously treated as infectious fevers due to lookalike symptoms. To diagnose tiger moth lepidopterism, we conducted immunoblots for tiger moth specific IgE in fever patients' sera. We selected a cohort of patients (n = 155) with hallmark symptoms of infectious fevers but were tested negative to infectious fevers. In these cases, the total IgE was elevated and was detected positive (78.6%) for tiger moth specific IgE allergens. Chemical characterization of caterpillar and adult moth fluids was performed by HPLC and GC-MS analysis and structural identification of moth scales was performed by SEM analysis. The body fluids and chitinous scales were found to be highly toxic and inflammatory in nature. To replicate the disease in experimental model, wistar rats were exposed to live tiger moths in a dose dependant manner and observed similar clinico-pathological complications reported during the fever epidemics. Further, to link larval abundance and fever epidemics we conducted cointegration test for the period 2009 to 2012 and physical presence of the tiger moths were found to be cointegrated with fever epidemics. In conclusion, our experiments demonstrate that inhalation of aerosols containing tiger moth fluids, scales and hairs cause systemic reactions that can be fatal to human. All these evidences points to the possible involvement of tiger moth disease as a major cause to the massive and fatal fever epidemics observed in Kerala.

Venomous and poisonous Australian animals of veterinary importance: a rich source of novel therapeutics

Envenomation and poisoning by terrestrial animals (both vertebrate and invertebrate) are a significant economic problem and health risk for domestic animals in Australia. Australian snakes are some of the most venomous animals in the world and bees, wasps, ants, paralysis ticks, and cane toads are also present as part of the venomous and poisonous fauna. The diagnosis and treatment of envenomation or poisoning in animals is a challenge and can be a traumatic and expensive process for owners. Despite the potency of Australian venoms, there is potential for novel veterinary therapeutics to be modeled on venom toxins, as has been the case with human pharmaceuticals. A comprehensive overview of envenomation and poisoning signs in livestock and companion animals is provided and related to the potential for venom toxins to act as therapeutics.

Processionary Caterpillar Setae and Equine Fetal Loss

Pregnant mares were experimentally exposed to whole caterpillar or exoskeleton of the Processionary caterpillar ( Ochrogaster lunifer) via gavage. Tissues were collected from resulting abortions and near or full-term pregnancies consisting of 13 aborted fetuses, 3 fetuses from treated euthanized mares, membranes of 5 foals, and organs from 3 foals. Three control membranes and 1 control fetus and membranes were examined. Caterpillar setal fragments were present in the allantochorion of the 3 fetuses from the euthanized mares and 11 of 12 aborted fetuses (92%) embedded in the chorion (villi or stroma) or allantois (vasculature or stroma). Placental locations of fragments ranged from the cervical pole region to the body encompassing the umbilical insertion and pregnant horn. Numbers in each fetus ranged from 1 to 7 fragments. Setae were present in the allantochorion from 2 to 22 days after the initial treatment. Acute to chronic active inflammation was present in all aborted fetuses, all euthanized fetuses, and within at least 1 tissue level (chorion, allantois, umbilical cord, or amnion) of the membranes from full-term foals. Amnionitis, funisitis, and allantoitis were present in 95% of the examined membranes. Pneumonia was present in 95% of the specimens, and bacteria were present histologically in 90.5% of the specimens with or without accompanying inflammation. The rapid migration of setae within 2 days after mare exposure suggests that direct setal migration into the fetal membranes is a likely initiating factor for equine amnionitis and fetal loss (EAFL).

Processionary caterpillar setae and equine fetal loss: 1. Histopathology of experimentally exposed pregnant mares

Six pregnant Standardbred mares aged between 6 and 14 years were gavaged with 50 g or 100 g of suspended emulsified whole Processionary caterpillars (Ochrogaster lunifer) for 5 days during 2 experiments undertaken to study the etiology of equine amnionitis and fetal loss (EAFL). The 6 treated mares and 1 untreated mare were between 128 and 252 days gestation. Mare 1 (untreated) was euthanized on day 5 of the treatment period, while the treated mares were euthanized on days 2, 4, 8, 10, 12, and 24 days from their first treatment. Caterpillar setae were not found in the untreated mare. Setal fragments were present in all regions of the gastrointestinal tracts in all treated mares, the uteri and mesenteric lymph nodes of 5 mares, and the liver of 4 mares. Acute gastroenteritis of varying severity was present in all treated mares, and 5 of 6 mares had acute colitis and endometritis. Focal hyperplastic serositis was found in the duodenum, cecum, dorsal colon, and uteri of various mares occasionally with embedded setal fragments. Setal invasion of the mucosa evoked a range of lesions including superficial erosion to deep ulceration. Inflammation in deeper tissues ranged from unapparent to neutrophilic (microabscesses), eosinophilic, or mononuclear (microgranulomas). The finding of setal fragments within the uterus of experimental mares suggests that direct migration of setal fragments acting as a bacterial vector is a likely mechanism for the bacterial abortions that characterize equine amnionitis and fetal loss.

'Everybody knows', but the rest of the world: the case of a caterpillar-borne reproductive loss syndrome in dromedary camels observed by Sahrawi pastoralists of Western Sahara

BACKGROUND

The traditional knowledge of local communities throughout the world is a valuable source of novel ideas and information to science. In this study, the ethnoveterinary knowledge of Sahrawi pastoralists of Western Sahara has been used in order to put forward a scientific hypothesis regarding the competitive interactions between camels and caterpillars in the Sahara ecosystem.

METHODS

Between 2005 and 2009, 44 semi-structured interviews were conducted with Sahrawi pastoralists in the territories administered by the Sahrawi Arab Democratic Republic, Western Sahara, using a snow-ball sampling design.

RESULTS

Sahrawi pastoralists reported the existence of a caterpillar-borne reproductive loss syndrome, known locally as duda, affecting their camels. On the basis of Sahrawi knowledge about duda and of a thorough literature review, we built the hypothesis that: 1) caterpillars of the family Lasiocampidae (genera Lasiocampa, Psilogaster, or Streblote) have sudden and rare outbreaks on Acacia treetops in the Western Sahara ecosystem after heavy rainfall; 2) during these outbreaks, camels ingest the caterpillars while browsing; 3) as a consequence of this ingestion, pregnant camels have sudden abortions or give birth to weaklings. This hypothesis was supported by inductive reasoning built on circumstantiated evidence and analogical reasoning with similar syndromes reported in mares in the United States and Australia.

CONCLUSIONS

The possible existence of a caterpillar-borne reproductive loss syndrome among camels has been reported for the first time, suggesting that such syndromes might be more widespread than what is currently known. Further research is warranted to validate the reported hypothesis. Finally, the importance of studying folk livestock diseases is reinforced in light of its usefulness in revealing as yet unknown biological phenomena that would deserve further investigation.