Person-to-Person Transmission in Emerging Viral Diseases: The Case of Andes Virus

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New-generation infectious diseases and re-emerging viral diseases are the major challenges to current globalization and urbanization trends. Of all these diseases, hantavirus diseases have been noticed to attract so much attention, especially because they cause respiratory diseases, and in most cases, the fatality rate is very high. A new virus associated with the Andes has been identified to be a part of the Hantaviridae family and distinguished from other Hantaviruses because it can be transmitted from one human to another. The utility of this feature of the Andes virus (ANDV) to public health initiatives is far-reaching, especially where the virus is prevalent, as in Argentina and Chile. ANDV is mainly spread through interactions with infected rodents, and, unlike relatives, it spreads through the air between people, which makes it especially dangerous. This blog discusses the epidemiology of the Andes virus, emphasizing mechanisms of transpersonal transmission and efforts to contain the virus.

Hantaviruses and Their Typical Transmission Routes

Hantaviruses are a group of rodent-borne viruses that humans get infected with through contact with the rodent’s saliva, urine, or feces. These viruses are responsible for two main types of diseases: Hemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome (HPS). In the Americas, HPS is the primary concern, with several hantaviruses causing the disease, which include the Sin Nombre virus, Choclo virus, and Andes virus. Most hantaviruses are transmitted zoonotic, with humans being incidental hosts exposed to affected utensils in homes and other dwellings. Most victims are from rural areas where rodent carriers are common. 

However, as we see in this typical transmission mode, the Andes virus possesses some variation. It is known to spread directly from person to person, and this is very fatal, especially during epidemics. Examining the peculiarities of ANDV transmission has been a key concern to scholars and control agencies in South America.

Anatomy of Transmission of New Andes Virus

Different from the Andes virus, many of the more than 65 hantaviruses are not contagious. It was first noted in Argentina during epidemics of the 1980s and 1990s, when cases of infection in houses and hospitals were clustered and scientists assumed that the virus transmits itself from person to person. Further molecular studies of the virus sample obtained from these patients in each of these clusters proved that the virus did not only occur among rodents but across people.

The primary zoonotic route of human-to-human transmission is thought to involve droplet aerosols. Physical proximity to an infected person, especially at the time when a person is contagious, that is to say at the beginning of the infection and before the onset of pyrexia and other symptoms, including respiratory manifestations. This mode of transmission is more worrying because it replicates the initiation behaviors common with other respiratory viruses, including influenza virus and SARS-CoV-2, where the virus can spread within homes for families or within health facilities.

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Outbreaks and Epidemiological Data

Several previous epidemics of the Andes virus in Argentina and Chile offered information about the transmission of this virus. A Southern Chile outbreak in 2011 was particularly characterized by hospital-acquired transmission. All four healthcare workers developed respiratory symptoms after attending to a patient paralyzed with ANDV, pointing to the possibility of hospital-acquired transmission. The genetic sequence investigation of those cases also proved that these HCWs were infected by the same strain of the virus from the patient, indicating the fact of person-to-person transmission.

More evidence of the human-to-human transmission of the virus came in 2014, when the disease re-emerged in Argentina. In this outbreak, there was secondary transmission of cases within one household, with physical contact with the affected family member recognized as a risk factor. In such cases, the duration of the incubation period was 9–33 days; however, after onset of fever, myalgias, and respiratory distress, symptoms deteriorated rapidly. Interpersonal spread was further supported by comparing the genomic sequences of the virus from the positive participants and determining that the same strain was present within the household.

The epidemiological information from these outbreaks, therefore, supports the need to identify early cases and isolate these patients to stop transmission. Unlike other hantaviruses, where the key approach is to minimize the interaction between people and rodents, ANDV has its focus on targeting the early identification of contacts and isolating measures similar to those of more familiar airborne viruses.

Factors Facilitating Person-to-Person Transmission

It was also found that there are characteristics of the Andes virus transmission that are person-to-person as opposed to other hantaviruses. First, the virus is more likely to be transmitted during the prodromal phase, where the symptoms are flu-like fever, tiredness, muscle aches, and joint pains. In this stage, no one may know they have a deadly virus and are more likely to be close to other people.

In addition, respiratory secretions seem to be the principal mode of the pathogen’s spread. Unlike most hantaviruses, which are transmitted through rodent feces, urine, or droppings, ANDV is readily isolated from the saliva and respiratory secretions of infected hosts. This makes casual contact, like kissing, using the same utensils, or caregiving, extremely dangerous. Other settings within hospitals are also considered to be at high risk because of high contact between healthcare personnel and patients, the example being the 2011 Chilean outbreak.

Cultural practices as well as living conditions in rural South America most likely contribute to the spread of the disease. Even in families, there are often many people living together in one household; this raises the possibility of a contact chain in the event that one of the family members gets sick. Likewise, the collective infrastructure in rural settings, such as the use of groups, including shared utensils, makes it easier for the virus to move within a small population.

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Clinical Presentation and Challenges in Diagnosis

Patients with Andes virus infection present the clinical signs and symptoms typical of patients infected with other hantaviruses, distinguished only by the development of HPS in the acute phase. Measles signs/symptoms are fever, headache, fatigue, muscle aches, and abdominal pain. They also mature into respiratory complications and shock as the pathogen advances. The death rate of HPS due to the Andes virus stands between 30% and 50%, and therefore HPS is considered a lethal virus.

Since ANDV is simple to contract, one of the biggest problems connected with the disease is the ability to make an early diagnosis. Due to the presence of vague initial symptoms and signs very much like other respiratory diseases, including influenza and COVID-19, the patients do not present themselves for treatment until the conditions worsen. Moreover, antibiotics required for hantavirus diagnosis are unavailable in the many parts of more developed countries’ rural areas where these kinds of outbreaks are witnessed to take place, along with the fact that most affected zones are poorly equipped for carrying out serious early identification and isolation of the cases.

Public Health Strategies for Controlling Person-to-Person Transmission

Due to the irregular means of spreading the Andes virus, relevant interventions have to focus on both zoonotic and human-to-human transmission routes. There is a continuing need for such rodent control measures as well as public health campaigns to avoid contact with rodent populations. However, further measures are needed to reduce the risk of direct person-to-person spreading, especially in hospitals as well as households.

Outbreak involves identifying people who may have contacted the virus so that public health officials may isolate them as a way of stopping the spread of the same. Generally in hospitals, standard precautions should be adhered to as the patient with infection isolates; therefore, the caregiver uses personal protective clothing. In this case, restrictions on movement and other forms of lockdowns, such as community quarantine, could be recommended during and after the breakout.

To date, developments in vaccines and antiviral treatments for hantaviruses, including ANDV, are still under investigation. However, there is no particular antiviral treatment that can be prescribed for hantavirus at the moment. Palliative care still takes its place as the main treatment used, and the role of intervention cannot be overemphasized.

Conclusion

In the arena of new/viral disease, the Andes virus poses new difficulty because of the possibility of human-to-human transmission. Unlike other hantaviruses, its transmission mode is person-to-person; this means that it cannot be controlled by a single method but needs a combined approach from the public health department. Although acute-acquired infection mostly occurs from rodent bites, the possibility of human-to-human transmission raises the severity of the virus, especially in areas of congregational platforms such as hospitals and confined neighborhoods. As pockets of ANDV exist in South America, more effort should be put into developing better diagnostics, alert systems, and effective policies that would curtail the further spread of this deadly virus.

References

  1. Alonso, D.O., Pérez-Sautu, U., Bellomo, C.M., Prieto, K., Iglesias, A., Coelho, R., Periolo, N., Domenech, I., Talmon, G., Hansen, R. and Palacios, G., 2020. Person-to-person transmission of Andes virus in hantavirus pulmonary syndrome, Argentina, 2014. Emerging infectious diseases, 26(4), p.756.
  2. Martinez-Valdebenito, C., Calvo, M., Vial, C., Mansilla, R., Marco, C., Palma, R.E., Vial, P.A., Valdivieso, F., Mertz, G. and Ferrés, M., 2014. Person-to-person household and nosocomial transmission of Andes hantavirus, Southern Chile, 2011. Emerging infectious diseases, 20(10), p.1629.
  3. Toledo, J., Haby, M.M., Reveiz, L., Sosa Leon, L., Angerami, R. and Aldighieri, S., 2022. Evidence for human-to-human transmission of hantavirus: a systematic review. The Journal of infectious diseases, 226(8), pp.1362-1371.
  4. Bayard, V., Kitsutani, P.T., Barria, E.O., Ruedas, L.A., Tinnin, D.S., Muñoz, C., De Mosca, I.B., Guerrero, G., Kant, R., Garcia, A. and Caceres, L., 2004. Outbreak of hantavirus pulmonary syndrome, Los Santos, Panama, 1999–2000. Emerging infectious diseases, 10(9), p.1635.
  5. Tian, H. and Stenseth, N.C., 2019. The ecological dynamics of hantavirus diseases: From environmental variability to disease prevention largely based on data from China. PLoS Neglected Tropical Diseases, 13(2), p.e0006901.
  6. Martinez, V.P., Bellomo, C., San Juan, J., Pinna, D., Forlenza, R., Elder, M. and Padula, P.J., 2005. Person-to-person transmission of Andes virus. Emerging infectious diseases, 11(12), p.1848.
  7. Kuhn, J.H., Bradfute, S.B., Calisher, C.H., Klempa, B., Klingström, J., Laenen, L., Palacios, G., Schmaljohn, C.S., Tischler, N.D. and Maes, P., 2023. Pending reorganization of Hantaviridae to include only completely sequenced viruses: A call to action. Viruses, 15(3), p.660.

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