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Acute anterior myelitis complicating West Nile fever.

A healthy young man developed acute anterior myelitis resembling the "polio syndrome." He had visited an area (the Gulf of Suez) in which West Nile fever is endemic prior to his illness. The course of his febrile illness, the spinal fluid findings, and complement fixation antibody titers established the diagnosis of West Nile fever. Meningoencephalitis is a serious, and previously the only known, complication of this usually benign febrile illness. This is the first report, to our knowledge, of another neurological complication, namely acute anterior myelitis.

Acute Disease

Hemorrhagic fevers, with special reference to recent outbreaks in southern Africa.

In considering the diagnosis of a patient admitted to the Johannesburg Hospital, suffering from an illness characterized by high fever and complicated by a hemorrhagic state from which he died, a list of possible causes of his illness was drawn up. This list included the arthropodborne viral infections prevalent in southern Africa, namely, chikungunya fever, Sindbis fever, West Nile fever, yellow fever, and Rift Valley fever; viral infections associated with rodents, such as Lassa fever; the viral infection associated with monkeys, Marburg virus disease; the rickettsial infections; tick-bite fever (the variety of spotted fever of tick typhus occurring in southern Africa) and Q fever; the bacterial infections, especially the coccal infections, plague septicemia, and meningococcal, staphylococcal, and streptococcal septicemia; and the blood protozoal infections malaria and trypanosomiasis. In addition, rubella, Gasser's syndrome, Henoch-Schönlein purpura, and viperine snakebite were briefly described in this review. All of these conditions may be complicated by the development of a hemorrhagic state. The circulation of large numbers of infecting organisms, by they viruses, rickettsiae, bacteria, or protozoa, may initiate the coagulation cascade, the formation of fibrin and its deposition in the finer blood vessels, and the aggregation and entanglement of platelets resulting in marked thrombocytopenia and bleeding. This bleeding tendency is greatly aggravated when the infection specifically involves the parenchymal cells of the liver; such a condition results in defective formation of coagulation factors such as prothrombin. The proper care of patients in whom a hemorrhagic state has developed requires urgent and accurate diagnosis followed by immediate and appropriate treatment that will combat the infection and alleviate the hemorrhagic state and liver disorder. If the hemorrhagic state is due to one of the dangerous infectious fevers, adequate protection of the medical, nursing, and laboratory staff concerned is also vital.

Adolescent

Seropositivity to Dengue, Zika, Yellow Fever, and West Nile Viruses in Senegal, West Africa.

West Africa serves as a critical region for the co-circulation of mosquito-borne flaviviruses, which often precipitate sporadic outbreaks. This study investigated the seropositivity to dengue virus serotypes 1-4 (DENV-1-4), Zika virus (ZIKV), yellow fever virus (YFV), and West Nile virus (WNV) in three regions of Senegal: Sindia, Thies, and Kedougou. We retrospectively analyzed 470 serum samples for flavivirus immunoglobulin G (IgG) using a DENV-2 envelope (E) ELISA. Our findings revealed an overall flavivirus seroprevalence of 37.23%. Among the DENV-2 E IgG positive samples, the proportion of subjects with IgG to DENV-1-4, ZIKV, YFV, or WNV NS1 was 57.14%, 12.57%, 80.57%, and 17.14%, respectively, with 66.86% harboring neutralizing antibodies against two or more flaviviruses. We also identified that residents in Sindia (ZIKV, aOR, 9.428; 95% CI: 1.882-47.223 and WNV, aOR, 6.039; 95% CI: 1.855-19.658) and Kedougou (ZIKV, aOR, 7.487; 95% CI: 1.658-33.808 and WNV, aOR, 1.142; 95% CI: 0.412-3.164) were at significant risk for ZIKV and WNV exposure. This study underscores the complexity of flavivirus epidemiology in West Africa and the necessity for enhanced surveillance to inform public health strategies.

Humans

Identifying genomic surveillance gaps in Africa for the global public health response to West Nile virus: a systematic review.

West Nile virus (WNV) is a priority pathogen that poses a high risk for public health emergencies of global concern. Although WNV is endemic to Africa, only few (n=63) whole genomic sequences are available from the continent. In this Review, we examined the status of the molecular testing and genomic sequencing of WNV across Africa and mapped its global spatiotemporal spread. WNV has been detected in 39 African countries, the Canary Islands, and Réunion Island. Although publications, including those with molecular data, originated from 24 of these countries, genomic sequences were available from only 16 countries. Our analysis identified regions with detected viral circulation but without molecular surveillance. The current literature has substantial knowledge gaps in terms of the disease burden, molecular epidemiology, and distribution of WNV in Africa. Addressing these gaps requires an integrated One Health surveillance approach, which is challenging to establish. We propose three key surveillance needs that could improve the current understanding of the WNV disease burden in Africa, to strengthen the global public health response to this vector-borne disease.

West Nile Fever

[Interferonogenic activity of gossypol, a low-molecular substance].

The interferonogenic activity of gossipol, a low molecular substance of polyphenolic nature was shown in the cell cultures of chick embryos and organisms of mice. Pronounced prophylactic efficiency of the drug in mice with experimental infection caused by the West Nile virus was found. Definite parallelism between the intensity of interferonogenesis and the protection level from the virus affection due to the use of gossipol in mice was noted. Difference between gossipol and other known low molecular inductors of interferon, such as dyes, tyloron, propandinamine is discussed. The possibility of using gossipol as an antiviral drug is presumed.

Animals

[Change in the nature of the persistence of alpha- and flaviviruses in the body of BALB/c strain mice with a mixed infection with leukovirus].

The features of pathogenesis of infection caused in adult Balb/c mice intraperitoneally infected with Sindbis virus, virulent or attenuated strains of West Nile (WN) virus, individually or in combination with Rauscher leukemia virus (RLV) were studied. The influence of the latter on the course of togavirus infections was characterized by 3 features: (a) different effects on the visceral and neural phases of the pathogenesis (increased period of viremia and virus reproduction in the viscera did not lead to stimulation of virus reproduction in the CNS); (b) changes in the time of togavirus persistence in the infectious form; (c) the dependence of the observed effect on the togavirus properties.

Animals

Comparison of vector competence for West Nile virus of colonized populations of Culex tritaeniorhynchus from southern Asia and the Far East.

Seven colonized stocks of Cx. tritaeniorhynchus from different geographic areas of Southern Asia and the Far East were assayed for susceptibility to WN virus infection by membrane feeding and by intrathoracic inoculation. Infected females also were tested for their ability to transmit virus to baby mice. No geographic pattern of differential susceptibility to WN virus infection was apparent from the experiments; however, the per os ID50 of one strain from Khulna, Bangladesh was over 10-fold greater than the ID50's of stocks from Karachi, Pakistan and Sendai, Japan. No difference in susceptibility was found by parenteral inoculation of virus. Likewise, greater than or equal to 90% of infected females from all the colonies were able to transmit virus.

Animals

Evaluation of Aedes albopictus tissue culture for use in association with arbovirus isolation.

The susceptibility and sensitivity of Aedes albopictus cell cultures to five different primary and four different low-passage arboviruses were tested. Yellow fever, West Nile, Ilesha, eastern equine encephalitis, and Flanders viruses replicated in A albopictus tissue cultures. Replication was determined by the ability of selected tissue culture fluids to infect suckling mice, and by recovery from tissue culture fluid of progressively increasing amounts of complement-fixing (CF) antigen with time. Virus persistence was demonstrated with Nodamura, western equine encephalitis, and Mayaro viruses, but multiplication was not proven; neither persistence nor multiplication was demonstrated with a Kemerovo group virus. When yellow fever and Ilesha viruses were simultaneously inoculated into A albopictus culture, CF antigen for each was consistently detected. In a more detailed comparative study of field specimens, 12 unpassaged strains of yellow fever virus were tested for infectivity in A albopictus tissue culture, Vero cells, and baby mice. Higher titers of virus were detected (0.8--2.3 log ID50 per ml) in Vero cell culture than in A albopictus tissue culture or baby mouse systems. These results suggest the feasibility of using A albopictus cells in association with the primary isolation of arboviruses.

Aedes

Dengue virus infections in Nigeria: a survey for antibodies in monkeys and humans.

A retrospective serological survey for dengue immunity was conducted in Nigeria to determine the prevalence of infection in man and non-human primates. Preliminary haemagglutination-inhibition (HI) tests revealed that 63% of persons tested had HI antibodies against one or more of the following flaviviruses: dengue type 1, yellow fever, West Nile and Wesselsbron. Parallel HI and neutralization (N) tests on 179 human sera showed that six of 20 sera (30%) negative for flavivirus HI antibody contained dengue N antibody. This finding emphasized the advantage of the N test over HI in screening for dengue virus immunity. Neutralization tests performed on 1,816 human sera from different geographical locations in Nigeria showed that 45% of Nigerians were immune to dengue type 2 virus. The percentage of immunity in adults aged 20 years and older (51%) was significantly higher than in children (37%) (P less than 0-01). In all four ecological zones sampled, the highest percentage of dengue N antibody was observed in the derived Savannah zone (63%) followed by the rain forest zone (42%). The Southern Guinea savannah and plateau zones had lower percentages of dengue-immune persons. There was a higher prevalence of antibodies in urban (48%) than in rural communities (37%). Tests on dengue-immune sera showed that 35% of such sera contained N antibodies to dengue only or to dengue and one other virus. Therefore, dengue immunity cannot be explained by heterologous cross reactions within the flavivirus group. In addition, evidence of dengue infection was found in monkeys and galagos. 48% of monkeys and 25% of galagos contained dengue N antibody. The presence of specific dengue N antibodies in a few sera suggests that the occurrence of a forest cycle of dengue is possible in Nigeria.

Animals

Human West Nile virus lineage 2 neuroinvasive infection as a cause of fatal Guillain-Barré syndrome.

BACKGROUND: West Nile virus (WNV) is now endemic in Europe and continues to spread to several countries, with strains 1 and 2 primarily responsible for outbreaks. According to the European Centre for Disease Prevention and Control (ECDC), Italy accounts for the majority of locally acquired cases and West Nile neuroinvasive disease (WNND). CASE REPORT: We present the first case described in Italy and Europe of WNND-related Guillain-Barré syndrome (GBS). Phylogenetic analysis showed that the genome belonged to the WNV-2, sublineage 2a, clustering within sequences from genomes originating mainly from Hungarian 578/10 strain, a particularly virulent strain. CONCLUSION: The first case of GBS as a presentation of WNND in a European patient is reported, along with a review of all previously published cases of GBS related to WNND. The United States Centers for Diseases Control and Prevention (CDC) documented 13% of WNV infections manifest as GBS, with a gradual and slow improvement, often with residual neurologic deficits of varying severity. Physicians should be aware that the presentation of a patient to an emergency department with GBS, during a certain epidemiological period of the year, should raise the clinical suspicion that the GBS may be related to a WNND.

Humans

Zika virus infections in Nigeria: virological and seroepidemiological investigations in Oyo State.

A study of Zika virus infections was carried out in four communities in Oyo State, Nigeria. Virus isolation studies between 1971 and 1975 yielded two virus isolations from human cases of mild febrile illness. Haemagglutination-inhibition tests revealed a high prevalence of antibodies to Zika and three other flaviviruses used. The percentages of positive sera were as follows: Zika (31%), Yellow fever (50%), West Nile (46%), and Wesselsbron (59%). Neutralization tests showed that 40% of Nigerians had Zika virus neutralizing antibody. Fifty per cent of zika virus immune persons had neutralizing antibody to Zika alone or to Zika and one other flavivirus. A total of 121 sera had antibody to Zika virus; of these 48 (40%) also showed antibody to two other flaviviruses, and 12 (10%) had antibodies to three or more other viruses. The percentage of neutralizing antibodies to other flaviviruses in Zika virus immune sera was 81% to Dengue type 1, 58% to Yellow fever, 7% to Wesselsbron, 6% to West Nile and 3% to Uganda S.

Aedes

A yellow fever epizootic in Zika Forest, Uganda, during 1972: Part 2: Monkey serology.

During the 1972 yellow fever epizootic in Zika Forest, Uganda, sera from 21 monkeys shot in a number of forests around the Entebbe area were tested for the presence of a number of arbovirus antibodies. All sera were tested for antibodies against Chikungunya (CHIK), O'nyong-nyong (ONN), Zika, yellow fever (YF) West Nile (WN) and Wesselsbron (WESS) by the haemagglutination-inhibition (HI) test. Because of the crossreaction within the flaviviruses (group B arboviruses) mouse protection test (PT) was also carried out on the sera against YF, WESS and Zika viruses. Serological studies carried out on monkey sera from different parts of Uganda, including the Entebbe area, during 1968 gave results which reflected a surprisingly low rate of YF immune monkeys (3%) throughout the country compared with the rate of over 40% immune monkeys obtained by Haddow et al. in 1951. 40% of the monkey sera collected during 1972 were immune to YF by the PT. Since no YF virus had been isolated between 1968 and 1972 the results indicate strongly that the monkeys in the Entebbe area were involved in the epizootic of 1972. No sick or dead monkeys were found in all the forests checked around Entebbe area during the epizootic. This indicates that the animal-to-animal cycle of the equatorial African forests involved the mild endemic infection characteristic of a virus in its natural habitat and infecting its natural host.

Animals

An immunopathologic component in experimental togavirus encephalitis.

The effects of immune manipulation upon survival and histopathology in two experimental group B togavirus encephalitides were studied in inbred mice. The median survival time 8 days after intracerebral injection of Langat virus increased to 10 days with an immunosuppressive course of cyclophosphamide, with concomitant reduction in the inflammatory response. Adoptive immunization with immune lymphoid cells or serum also tended to prolong Langat virus survival while increasing inflammation. Survival following intracerebral West Nile virus (7 days) was unaffected by immunosuppression or adoptive transfer, although suppression was associated with less severe CNS lesions, and immune serum with less necrosis. These findings indicate that the immune response may be both protective and pathology-inducing in some togarvirus encephalitides. The differences in host response to these two related agents suggest caution in generalizing about the role of the immune response in viral infections.

Animals

Influence of certain immunodepressants on experimental flavivirus and enterovirus infections in mice.

The effects of cyclophosphamide and 1,3-(piperidinomethyl)-5-phenyl-5-ethylbarbituric acid on certain flavi- and enterovirus infections in mice were studied. Differential enhancement of mortality rates after extraneural and, less markedly, intracerebral virus inoculation was noted. While depression of humoral and/or cell-mediated immunity is considered to be responsible for the effects observed in flavivirus infections, impaired function of the reticuloendothelial system seems to contribute mainly to the potentiation of Mengo virus infection by the immunodepressants used.

Animals