An Updated Review of the Invasive Aedes albopictus in the Americas; Geographical Distribution, Host Feeding Patterns, Arbovirus Infection, and the Potential for Vertical Transmission of Dengue Virus

The aim of the work was to update the distribution range of Aedes (Stegomyia) albopictus Skuse in the Americas, review the blood-feeding patterns and compare the minimum infection rate (MIR) of the dengue virus (DENV) between studies of vertical and horizontal transmission. The current dis-tribution of Ae. albopictus encompasses 21 countries in the Americas. Extensive review has been conducted for the blood-feeding patterns of Ae. albopictus. The results suggest that the mosquito is capable of feeding on 16 species of mammals and five species of avian. Humans, dogs, and rats are the most common host. Eight arboviruses with the potential to infect humans and animals have been isolated in Ae. albopictus. In the United States of America (USA), Eastern equine encephalitis virus, Keystone virus, La Crosse Virus, West Nile virus, and Cache Valley virus were isolated in the Asian mosquito. In Brazil, Mexico, Colombia, and Costa Rica, DENV (all serotypes) has been frequently identified in field-caught Ae. albopictus. Overall, the estimated MIR in Ae. albopictus infected with DENV is similar between horizontal (10.95) and vertical transmission (8.28). However, in vertical transmission, there is a difference in the MIR values if the DENV is identified from larvae or adults (males and females emerged from a collection of eggs or larvae). MIR es-timated from larvae is 14.04 and in adults is 4.04. In conclusion, it has to be highlighted that Ae. albopictus is an invasive mosquito with wide phenotypic plasticity to adapt to broad and new areas, it is highly efficient to transmit the DENV horizontally and vertically, it can participate in the inter-endemic transmission of the dengue disease, and it can spread zoonotic arboviruses across forest and urban settings.

Linear and Continuous Flavivirus Epitopes From Naturally Infected Humans

This manuscript is an up-to-date review of experimentally validated linear and continuous epitopes identified from arbovirus members of the Flavivirus genus. We summarized 153 immunoreactive peptides from the Dengue virus, Zika virus, Japanese encephalitis virus, West Nile virus, and tick-borne encephalitis virus described in studies published from 1989 to 2020. We included peptides from structural (envelope, capsid, and pre-membrane) and nonstructural (Ns1–5) viral proteins that demonstrated relevant immunoreactivity with antibodies from naturally infected or vaccinated humans. We included peptides that demonstrated relevant reactivity features, such as indicators of disease severity related to immunological or immunopathological outcomes, differential or group diagnostic markers, immunotherapy candidates, and potential for vaccine formulation. The majority of immunoreactive peptides were described for DENV probably due to its long-lasting impact on human health and the lack of efficient vaccines and therapeutic methods. Immune landscape data regarding linear immunoreactive and continuous flavivirus peptides are still scarce, and a complete and more detailed map remains to be elucidated. Therefore, this review provides valuable data for those investigating the antibody response against flavivirus infection.

Serosurvey of Nonhuman Primates in Costa Rica at the Human–Wildlife Interface Reveals High Exposure to Flaviviruses

Arthropod-borne viruses belonging to the flavivirus genus possess an enormous relevance in public health. Neotropical non-human primates (NPs) have been proposed to be susceptible to flavivirus infections due to their arboreal and diurnal habits, their genetic similarity to humans, and their relative closeness to humans. However, the only known flavivirus in the American continent maintained by sylvatic cycles involving NPs is yellow fever virus (YFV), and NPs’ role as potential hosts of other flaviviruses is still unknown. Here, we examined flavivirus exposure in 86 serum samples including 83.7% samples from free-range and 16.3% from captive NPs living in flavivirus-endemic regions of Costa Rica. Serum samples were opportunistically collected throughout Costa Rica in 2000–2015. We used a highly specific micro-plaque reduction neutralization test (micro-PRNT) to determine the presence of antibodies against YFV, dengue virus 1–4 (DENV), Zika virus, West Nile virus (WNV), and Saint Louis encephalitis virus (SLEV). We found evidence of seropositive NPs with homotypic reactivity to SLEV 11.6% (10/86), DENV 10.5% (9/86), and WNV 2.3% (2/86). Heterotypic reactivity was determined in 3.5% (3/86) of individuals against DENV, 1.2% (1/86) against SLEV, and 1.2% (1/86) against WNV. We found that 13.9% (12/86) of NPs were positive for an undetermined flavivirus species. No antibodies against DENV-3, DENV-4, YFV, or ZIKV were found. This work provides compelling serological evidence of flavivirus exposure in Costa Rican NPs, in particular to DENV, SLEV, and WNV. The range of years of sampling and the region from where positives were detected coincide with those in which peaks of DENV in human populations were registered, suggesting bidirectional exposure due to human–wildlife contact or bridging vectors. Our work suggests the continuous exposure of wildlife populations to various flaviviruses of public health importance and underscores the necessity of further surveillance of flaviviruses at the human–wildlife interface in Central America.

Culex mosquitoes (Diptera: Culicidae) recorded along the Nile River in central and northern Sudan, with a key for the identification of all species of the genus known to occur in the country

Despite the importance of Culex species as major vectors of Rift Valley fever virus, West Nile virus and the microfilariae that cause lymphatic filariasis, information on these mosquitoes in Sudan is limited to works published 65 years ago in the former Anglo-Egyptian Sudan, where some species were only recorded from areas of the territory now known as South Sudan. In this paper, we provide updated information on Culex mosquitoes collected indoors during surveillance studies conducted along the Nile River in central and northern areas of Sudan between 2012 and 2019. Of 3,411 female mosquitoes collected in Khartoum and northern states along the river, 2,560 (75%) were specimens of Culex belonging to 12 species: Cx. (Culex) antennatus (Becker, 1903), Cx. (Cux.) laticinctus Edwards, 1913, Cx. (Cux.) neavei Theobald, 1906, Cx. (Cux.) pipiens Linnaeus, 1758, Cx. (Cux.) perexiguus Theobald, 1903, Cx. (Cux.) poicilipes (Theobald, 1903), Cx. (Cux.) quinquefasciatus Say, 1823, Cx. (Cux.) simpsoni Theobald, 1905, Cx. (Cux.) sinaiticus Kirkpatrick, 1925, Cx. (Cux.) theileri Theobald, 1903, Cx. (Cux.) tritaeniorhynchus Giles, 1901 and Cx. (Culiciomyia) macfiei Edwards, 1923. This is the first record for Cx. tritaeniorhynchus and Cx. macfiei in central Sudan. The relative abundance of each species varied in different areas and seasons, but Cx. antennatus and Cx. quinquefasciatus were the most abundant indoor resting species. We provide an updated dichotomous key for the identification of the adults of Culex mosquitoes known to occur in the Republic of the Sudan.

Pigeon rotavirus A genotype G18P[17]-associated disease outbreaks after fancy pigeon shows in Germany – a case series

Objective Pigeon rotavirus A (RVA) isolates of genotype G18P[17] are causing disease outbreaks and fatalities in pigeon lofts in Australia, Germany, Belgium, Denmark and USA since 2016. Most disease outbreaks have been reported from juvenile pigeons (Columba livia forma domestica). However, reports on RVA-associated disease outbreaks in fancy pigeons in connection with fancy pigeon shows in Germany are rare. Material and methods Overall 18 pigeons (16 fancy pigeons and one racing pigeon from 9 pigeon fanciers, as well as one feral pigeon from a rescue center) were sent in for routine diagnostic necropsy including histopathologic, parasitologic and microbiologic examinations. Molecular biologic examinations for detection of RVA, circovirus, Usutu virus, West Nile virus and Chlamydia psittaci were also carried out on all pigeons. An accompanying questionnaire filled in by the senders was used to generate basic information on the affected pigeon lofts. Results Disease outbreaks in juvenile and adult pigeons were reported 7–14 days after fancy pigeon shows. One fancier who had previously vaccinated his pigeons with an autogenous pigeon RVA vaccine, noted no morbidity and mortality among his pigeons and thus sent in a healthy pigeon for diagnostic purposes. Reported clinical signs in the other pigeons were regurgitation, green slimy diarrhea, anorexia, apathy and death after 24 hours. Hepatic necrosis and detection of pigeon RVA isolates of genotype G18P[17] confirmed disease outbreaks caused by pigeon RVA in all pigeons, except for the vaccinated pigeon. Besides pigeon circovirus, which was detected in 15 of 18 pigeons, all other pathogens were singular findings. Conclusion and clinical relevance In disease outbreaks following fancy pigeon shows in juvenile and adult pigeons diagnostics should include pigeon RVA of genotype G18P[17].

Mosquito—Virus Interactions

Vector-borne viruses (arboviruses) are emerging threats to both human and animal health. The global expansion of dengue virus, West Nile virus, chikungunya, and most recently Zika virus are prominent examples of how quickly mosquito-transmitted viruses can emerge and spread. We currently lack high quality data from a diversity of mosquito-arbovirus systems on the specific mosquito and viral traits that drive disease transmission. Further, the factors that contribute to variation in these traits and disease transmission remain largely unidentified. In this chapter, we outline and explore the following: 1. the specific mechanisms governing the outcome of vector-virus interactions 2. how genetic variation across mosquito populations and viral strains, as well as environmental variation in abiotic and biotic factors shape the mosquito-virus interaction and 3. the implications of these interactions for understanding and predicting arbovirus transmission, as well as for control of mosquito species that transmit human pathogens.

The Use of Adjunctive Steroids in Central Nervous Infections

Central nervous system (CNS) infections continue to be associated with significant neurological morbidity and mortality despite various existing therapies. Adjunctive steroid therapy has been employed clinically to reduce inflammation in the treatment of CNS infections across various causative pathogens. Steroid therapy can potentially improve clinical outcomes including reducing mortality rates, provide no significant benefit, or cause worsened outcomes, based on the causative agent of infection. The data on benefits or harms of adjunctive steroid therapy is not consistent in outcome or density through CNS infections, and varies based on the disease diagnosis and pathogen. We summarize the existing literature on the effects of adjunctive steroid therapy on outcome for a number of CNS infections, including bacterial meningitis, herpes simplex virus, West Nile virus, tuberculosis meningitis, cryptococcal meningitis, Angiostrongylus cantonensis, neurocysticercosis, autoimmune encephalitis, toxoplasmosis, and bacterial brain abscess. We describe that while steroid therapy is beneficial and supported in pathogens such as pneumococcal meningitis and tuberculosis, for other diseases, like Listeria monocytogenes and Cryptococcus neoformans they are associated with worse outcomes. We highlight areas of consistent and proven findings and those which need more evidence for supported beneficial clinical use of adjunctive steroid therapy.

Arbovirus and seizures

The high prevalence and spread of arthropod-borne viruses (arboviruses) make them an important cause of viral encephalitis in humans. Most epidemic viral encephalitides have an etiology associated with arboviruses. Among various arboviruses, the Japanese encephalitis virus, West Nile virus, Zika virus, Dengue virus and Chikungunya virus can induce seizures. Arboviruses of the genus Flavivirus are usually transmitted by mosquitoes and other host animals. These vector-borne pathogens can cause epidemic viral encephalitis. Seizures may not be the major manifestation in these viral encephalitides, but may predict a poor prognosis. In this article, we discuss the relationships between these viruses and seizures from perspectives of clinical characteristics, pathogenesis, prognosis and treatments of each.