New World screwworm (Cochliomyia hominivorax) myiasis in feral swine of Uruguay: One Health and transboundary disease implications.

BACKGROUND: Feral swine (Sus scrofa) are highly invasive and threaten animal and human health in the Americas. The screwworm (Cochliomyia hominivorax) is listed by the World Organization for Animal Health as a notifiable infestation because myiasis cases affect livestock, wildlife, and humans in endemic areas, and outbreaks can have major socioeconomic consequences in regions where the screwworm has been eradicated. However, a knowledge gap exists on screwworm infestation of feral swine in South America, where the screwworm is endemic. Here, we report screwworm infestation of feral swine harvested in Artigas Department (Uruguay), where the Republic of Uruguay shares borders with Brazil and Argentina. METHODS: Myiasis caused by the larvae of screwworm were identified in feral swine with the support and collaboration of members of a local feral swine hunting club over a 3-year period in the Department of Artigas. Harvested feral swine were examined for the presence of lesions where maggots causing the myiasis could be sampled and processed for taxonomic identification. The sites of myiasis on the body of infested feral swine and geospatial data for each case were recorded. The sex and relative size of each feral swine were also recorded. Temperature and precipitation profiles for the region were obtained from public sources. RESULTS: Myiases caused by screwworms were recorded in 27 of 618 the feral swine harvested. Cases detected in males weighing > 40 kg were associated with wounds that, due to their location, were likely caused by aggressive dominance behavior between adult males. The overall prevalence of screwworm infestation in the harvested feral swine was associated with ambient temperature, but not precipitation. Case numbers peaked in the warmer spring and summer months. CONCLUSIONS: This is the first report on myiasis in feral swine caused by screwworm in South America. In contrast to myiasis in cattle, which can reach deep into host tissues, screwworms in feral swine tended to cause superficial infestation. The presence of feral swine in screwworm endemic areas represents a challenge to screwworm management in those areas. Screwworm populations maintained by feral swine may contribute to human cases in rural areas of Uruguay, which highlights the importance of the One Health approach to the study of this invasive host species-ectoparasite interaction.

Molecular Characterization of the 2016 New World Screwworm (Diptera: Calliphoridae) Outbreak in the Florida Keys.

New World screwworm (NWS), Cochliomyia hominivorax (Coquerel 1858) (Diptera: Calliphoridae), is a myiasis-causing fly that can be a serious threat to the health of livestock, wildlife, and humans. Its progressive eradication from the southern United States, Mexico, and Central America from the 1950s to 2000s is an excellent example of successful pest management using sterile insect technique (SIT). In late 2016, autochthonous NWS were detected in the Florida Keys, representing this species' first invasion in the United States in >30 yr. Rapid use of quarantine and SIT was successful in eliminating the infestation by early 2017; however, the geographic source of this infestation remains unknown. Here, we use amplicon sequencing to generate mitochondrial and nuclear sequence data representing all confirmed cases of NWS from this infestation, and compare these sequences to preexisting data sets sampling the native distribution of NWS. We ask two questions regarding the FL Keys outbreak. First, is this infestation the result of a single invasion from one source, or multiple invasions from different sources? And second, what is the geographic origin of this invasion? We found virtually no sequence variation between specimens collected from the FL Keys outbreak, which is consistent with a single source of introduction. However, we also found very little geographic resolution in any of the data sets, which precludes identification of the source of this outbreak. Our lack of success in answering our second question speaks to the need for finer-scale genetic or genomic assessments of NWS population structure, which would facilitate source determination of potential future outbreaks.

Characterization and utilization of microsatellite loci in the New World screwworm fly, Cochliomyia hominivorax.

New World screwworm populations in North and Central America have been the targets of virtually continuous eradication attempts by sterile insect technique (SIT) since the 1950s. Nevertheless, in some areas, such as Jamaica, SIT control programmes have failed. Reasons for the failure of SIT-based control programmes in some locations are unknown, but it has been hypothesized that failure may be related to mating incompatibility between sterile and wild fly populations or to the existence of sexually incompatible cryptic species. This paper outlines the development of a suite of four new microsatellite loci which can be used to study intra-specific relationships between populations of Cochliomyia hominivorax from the Caribbean and South America, which represent those populations involved in, or earmarked for, forthcoming SIT control. Cross-amplification with the secondary screwworm, Cochliomyia macellaria, was also successful with three of the new loci. We present results which suggest that populations from Trinidad and Jamaica form distinct groupings of flies and that C. hominivorax from Trinidad appears particularly distinct.

Miíases humanas / Human myiasis

Condição mórbida causada por ectoparasitos - larvas de vetores dípteros. Podem ser classificados, de acordo com a natureza do agente etiológico, em específicas, semi-específicas e acidentes ou, ainda, em miíase cutânea ou cavitária. O diagnóstico é estabelecido em bases clínicas. O tratamento consiste na remoção mecânica de cada uma das larvas ou no oclusão do óstio de entrada da lesão, a fim de sufocar o parasito. O artigo objetiva a revisão de aspectos relevantes, correlacionados com a parasitose

Screwworms.

New World and Old World screwworms pose threats to the livestock industry in the United States and other countries. Diligence on the part of veterinarians, physicians, and their respective staffs is essential to protect the livestock industry.

Observations on the New World screwworm fly in Libya and the risk of its entrance into Egypt.

Data on traumatic myiasis caused by Cochliomyia hominivorax in Libya were reported from August 1988 until February 1989. A total of 468 cases of screwworm myiasis were recorded in seven species of livestock and 229 humans, mainly children, were also found to be infested. Cattle and sheep were the most common hosts in livestock. In cattle, the principal infestation site was the umbilicus of neonates; in sheep, it was mainly the fatty tail. Animal myiasis reached its peak in October and November, but disappeared abruptly in winter on the onset of cold weather. Screwworm distribution was confined to the northwest of Libya. The potential dispersion of the fly from this area and the possibility of infestation of other countries, particularly Egypt, are discussed. Food and Agriculture Organization (FAO) efforts to confront the New World screwworm problem in Africa are mentioned.

Myiasis: the battle continues against screwworm infestation.

The New World screwworm fly (Cochliomyia hominivorax) caused myiasis extensively among livestock in Mexico and the southern third of the USA until eradication was achieved by repeatedly releasing sterile males of the species on a massive scale. The pest appeared in Libya in 1988, the first time it had become established outside the western hemisphere. Because of the threat of myiasis in animals and people, not only in Libya but also elsewhere in Africa and beyond, a concerted campaign of sterile male releases was mounted with strong international support, and the outbreak has been eliminated. Action is continuing against the pest in Central America.

Internal human myiasis

Data are presented on a case of internal myiasis which occurred in hospital. A patient, suffering from a cerebrovascular accident and presumed endometrial carcinoma with an offensive, purulent, copious blood-stained vaginal discharge, developed tachypnoea. A nasopharyngeal aspirate produced 40 fully developed screworm - Cochliomyia hominivorax (Coquerel) - larvae. The attraction of the gravid adult female fly to such a host and the significance of such cases are discussed.(AU)