Viruses Across the World

Special Feature

By Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor for Infectious Disease Alert.

Source: The ProMED listserv and other sources are efflorescent with reports of outbreaks of viral infections around the world, some of which I have summarized here.

Chikungunya in Italy1

Between july 4th and august 28th 2007, more than 100 residents of Castiglione di Cervia and Castiglione di Ravenna, adjacent villages separated by the River Savio, suffered acute febrile illnesses with myalgias, arthralgis, and frequently, skin rash.1 Further cases occurred and, as of September 13th, 2007, a total of 254 have been identified in the Emilia Romagna Region. Laboratory investigation identified chikungunya virus as the etiologic agent, with evidence of Aedes albopictus having served as the vector. This was the first time that this mosquito has been involved in an outbreak of human illness in Europe.

The epidemic of chikungunya infections actually began in Kenya in 2004 and the Comoros Islands in 2005, with subsequent spread to other islands in the Indian Ocean.2,3 Of the 770,000 residents of Reunion, 265,000 became ill, and syndromes not formerly associated with chikungunya, such as meningoencephalitis, were observed, albeit rarely. The mortality rate was approximately 1%. Travelers to Indian Ocean sites also began presenting to clinicians in Europe with chikungunya fever. Subsequent spread to India, where the number of cases is likely to be in the millions, guaranteed that additional cases would be detected in travelers from countries other than those in Europe, and I and my colleagues have seen a number of cases in Indian residents of Silicon Valley who had returned from visits back home. In some cases, the febrile illness had already resolved by the time they presented, but they were left with severe, often disabling arthralgias that lasted months. (I wonder how many have had futile "million" rheumatologic evaluations?)

The vectors of chikungunya are Aedes aegypti in Africa and Aedes albopictus in the Indian Ocean islands. Since the latter is present in tropical and temperate regions in many areas of the world, it was predicted to only be a matter of time until the virus took hold in one or more of these areas, with establishment of local patterns of transmission,3 an event which has now happened in Italy.

Dengue in Texas4

Between 1980-1999, 64 cases of autochthonously-transmitted dengue fever were identified on the Texas side of the border with Mexico. A cross-sectional serosurvey in Brownsville, Texas, and Matamoros, Tamaulipas, Mexico, performed in the autumn of 2004, has now demonstrated that this is a vast underestimate of the cases of dengue occurring in that area. In Brownsville, 40% of residents had serological evidence of past dengue infection, while this was true of 40% of those across the Rio Grande in Matoros. Mosquito larvae (Aedes aegypti, Aedes albopictus, Culex quinquefasciatus) were detected in 30% of households in each municipality, and there was serological evidence of recent dengue infection in 2% on the Texas side and 7.3% on the Mexican side. Neutralization studies indicated that the circulating dengue viruses were of serotypes 1 and 2.

Marburg in Uganda5

Although a small outbreak of Marburg virus infection at an underground gold mine in Uganda was declared ended in August 2007, a new case has now been reported. The first identified case died on July 14th, with a small number of cases subsequently observed; the mine was closed. The new case, however, occurred in a man who was guarding the closed mine, but nonetheless elected to enter it, presumably to find some gold for himself.

Marburg, like the agent of Ebola hemorrhagic fever, is a filovirus. Marburg was first identified at the Marburg Virus Institute in Germany, in monkeys that had been imported from Uganda. Recent serological data suggest that Marburg, like Ebola, is carried by bats,6 which were abundant in and around the Ugandan goldmine. A much larger outbreak of Marburg hemorrhagic fever than that discussed here occurred in the Democratic Republic of Congo, which borders Uganda, in goldminers in 1998. That outbreak terminated contemporaneously with the flooding of the mine. An outbreak in Angola in 2004-2005 was associated with 150 deaths. Finally, 6 people have died of Marburg in Congo since April 2007.

Ebola in the Democratic Republic of Congo (DRC)5

The health ministry of the DRC announced on October 2, 2007, that a 25th case of Ebola virus infection had been confirmed as part of an outbreak centered in the Kambugu zone, approximately 150 km from the capital city of Kinshasa. There have been 10 deaths, with the current case fatality rate estimated at 40%. An additional 49 cases are under investigation.

Ross River virus in Australia5

Ninety-three people have been reported to be infected with Ross River virus in the southern Brisbane area of Queensland in recent weeks, an approximate 300% increase from the number reported during the same period in each of the 5 previous years. This mosquito-borne alphavirus (Family: Togaviridae) can cause prolonged disability because of the frequent occurrence of long-persisting arthralgias. In the past, the joint involvement, which led to the description of epidemics of "benign polyarthritis" in the 1920s, has previously led to the misdiagnoses of acute rheumatic fever or gonococcal arthritis.

Rift Valley fever in Kenya5

On September 20th, it was announced that the deaths of 2 women in the Nakuru district, an area frequented by tourists, was due to Rift Valley fever. These cases raised concern about the potential resurgence of this infection in East Africa, where outbreaks had occurred earlier in the year. A total of 684 cases, with 155 deaths, had occurred in Kenya from November 2006 to March 2007, and in Tanzania, there had been 264 cases, including 109 deaths, which had been recorded between January 13th and May 3rd. Additional cases of infection with this bunyavirus have occurred in Somalia in the Horn of Africa.

Japanese encephalitis virus (JEV) in India5

Twelve deaths reported September 29, 2007, brought the total number of childhood deaths due to JEV in eastern Uttar Pradesh, since January, to 227. This outbreak, which is a yearly occurrence, is somewhat larger than that in 2006, an unfortunate occurrence for an infection that is vaccine-preventable.

Zika in Yap6

This outbreak, discussed in the September 2007 issue of Infectious Disease Alert, judging from the lack of additional reporting, has apparently resolved.

References

1. Angelini R, et al. An outbreak of chikungunya fever in the province of Ravenna, Italy. 2007;12:E070906.1.

2. Deresinski S. That Which Bends Up. Infect Dis Alert. 2006;25:68-70.

3. Charrel RN, et al. Chikungunya outbreaks — The globalization of vectorborne diseases. N Engl J Med. 2007;356:769-771.

4. Brunkard JM, et al. Dengue fever seroprevalence and risk factors, Texas — Mexico border, 2004. Emerg Infect Dis. 2007; October; [Epub ahead of print].

5. Towner JS, et al. Marburg virus infection detected in a common African bat. PLoS ONE. 2007;2:e764.

6. Deresinski S. Zika in Yap. Infect Dis Alert. 2007;26:134-135