Ne joilla puoli vuosisataa sitten on ollut voimassa oleva isorokkorokotus, mahdollisesti omaavat edelleen tätä pox-viruslajia vastaan ehkä 85% suojaa erään lähteen mukaan. Satun itse olemaan kahdesti rokotettu isoarokkoa vastaan, 1967 ja 1972, Israelin matkojeni yhteydessä. Jälkimmäinn rokote tuli saatua Nasaretissa, koska siellä sairaalaväki rokotettiin Syyriassa ilmenneen isorokkotapauksen takia. Ensimmäisen kerran otin rokotuksen, koska se oli vaatimuksena Israelin matkalle lähtöön. Iisorokosta sinänsä ei ole kuulunut kai mitään niiten vuosikymmenien jälkeen, muta virusta säilytetään jossain varalta , ehkä mahdollisiin tulevisuuden rokotetarpeisiin.
Nyt lehdistössä puhutaan tuosta monkeypox-tyypistä, jota on ilmennyt ihmiskunnan puolella. Etsin WHO:n . kirjoituksen tästä asiasta:
Key facts
- Monkeypox is caused by monkeypox virus, a member of the Orthopoxvirus genus in the family Poxviridae.
- Monkeypox is a viral zoonotic disease that occurs primarily in
tropical rainforest areas of Central and West Africa and is occasionally
exported to other regions.
- Monkeypox typically presents clinically with fever, rash and swollen
lymph nodes and may lead to a range of medical complications.
- Monkeypox is usually a self-limited disease with the symptoms
lasting from 2 to 4 weeks. Severe cases can occur. In recent times, the
case fatality ratio has been around 3-6%.
- Monkeypox is transmitted to humans through close contact with an
infected person or animal, or with material contaminated with the virus.
- Monkeypox virus is transmitted from one person to another by close
contact with lesions, body fluids, respiratory droplets and contaminated
materials such as bedding.
- The clinical presentation of monkeypox resembles that of smallpox, a
related orthopoxvirus infection which was declared eradicated worldwide
in 1980. Monkeypox is less contagious than smallpox and causes less
severe illness.
- Vaccines used during the smallpox eradication programme also
provided protection against monkeypox. Newer vaccines have been
developed of which one has been approved for prevention of monkeypox
- An antiviral agent developed for the treatment of smallpox has also been licensed for the treatment of monkeypox.
Introduction
Monkeypox is a
viral zoonosis (a virus transmitted to humans from animals) with
symptoms very similar to those seen in the past in smallpox patients,
although it is clinically less severe. With the eradication of smallpox
in 1980 and subsequent cessation of smallpox vaccination, monkeypox has
emerged as the most important orthopoxvirus for public health. Monkeypox
primarily occurs in Central and West Africa, often in proximity to
tropical rainforests and has been increasingly appearing in urban areas.
Animal hosts include a range of rodents and non-human primates.
The pathogen
Monkeypox virus is an enveloped double-stranded DNA virus that belongs to the Orthopoxvirus genus of the Poxviridae
family. There are two distinct genetic clades of the monkeypox virus –
the Central African (Congo Basin) clade and the West African clade. The
Congo Basin clade has historically caused more severe disease and was
thought to be more transmissible. The geographical division between the
two clades has so far been in Cameroon - the only country where both
virus clades have been found.
Natural host of monkeypox virus
Various
animal species have been identified as susceptible to monkeypox virus..
This includes rope squirrels, tree squirrels, Gambian pouched rats,
dormice, non-human primates and other species. Uncertainty remains on
the natural history of monkeypox virus and further studies are needed to
identify the exact reservoir(s) and how virus circulation is maintained
in nature.
Outbreaks
Human monkeypox was first
identified in humans in 1970 in the Democratic Republic of the Congo in a
9-year-old boy in a region where smallpox had been eliminated in 1968.
Since then, most cases have been reported from rural, rainforest regions
of the Congo Basin, particularly in the Democratic Republic of the
Congo and human cases have increasingly been reported from across
Central and West Africa.
Since 1970, human cases of monkeypox
have been reported in 11 African countries – Benin, Cameroon, the
Central African Republic, the Democratic Republic of the Congo, Gabon,
Cote d’Ivoire, Liberia, Nigeria, the Republic of the Congo, Sierra
Leone, and South Sudan. The true burden of monkeypox is not known. For
example, in 1996–97, an outbreak was reported in the Democratic Republic
of the Congo with a lower case fatality ratio and a higher attack rate
than usual. A concurrent outbreak of chickenpox (caused by the varicella
virus, which is not an orthopoxvirus) and monkeypox was found which
could explain real or apparent changes in transmission dynamics in this
case. Since 2017, Nigeria has experienced a large outbreak, with over
500 suspected cases and over 200 confirmed cases and a case fatality
ratio of approximately 3%. Cases continue to be reported until today.
Monkeypox
is a disease of global public health importance as it not only affects
countries in West and Central Africa, but the rest of the world. In
2003, the first monkeypox outbreak outside of Africa was in the United
States of America and was linked to contact with infected pet prairie
dogs. These pets had been housed with Gambian pouched rats and dormice
that had been imported into the country from Ghana. This outbreak led to
over 70 cases of monkeypox in the U.S. Monkeypox has also been reported
in travelers from Nigeria to Israel in September 2018, to the United
Kingdom in September 2018, December 2019, May 2021 and May 2022, to
Singapore in May 2019, and to the United States of America in July and
November 2021. In May 2022, multiple cases of monkeypox were identified
in several non-endemic countries. Studies are currently underway to
further understand the epidemiology, sources of infection, and
transmission patterns.
Transmission
Animal-to-human
(zoonotic) transmission can occur from direct contact with the blood,
bodily fluids, or cutaneous or mucosal lesions of infected animals. In
Africa, evidence of monkeypox virus infection has been found in many
animals including rope squirrels, tree squirrels, Gambian poached rats,
dormice, different species of monkeys and others. The natural reservoir
of monkeypox has not yet been identified, though rodents are the most
likely. Eating inadequately cooked meat and other animal products of
infected animals is a possible risk factor. People living in or near
forested areas may have indirect or low-level exposure to infected
animals.
Human-to-human transmission can result from close
contact with respiratory secretions, skin lesions of an infected person
or recently contaminated objects. Transmission via droplet respiratory
particles usually requires prolonged face-to-face contact, which puts
health workers, household members and other close contacts of active
cases at greater risk. However, the longest documented chain of
transmission in a community has risen in recent years from six to nine
successive person-to-person infections. This may reflect declining
immunity in all communities due to cessation of smallpox vaccination.
Transmission can also occur via the placenta from mother to fetus (which
can lead to congenital monkeypox) or during close contact during and
after birth. While close physical contact is a well-known risk factor
for transmission, it is unclear at this time if monkeypox can be
transmitted specifically through sexual transmission routes. Studies are
needed to better understand this risk.
Signs and symptoms
The
incubation period (interval from infection to onset of symptoms) of
monkeypox is usually from 6 to 13 days but can range from 5 to 21 days.
The infection can be divided into two periods:
- the
invasion period (lasts between 0-5 days) characterized by fever,
intense headache, lymphadenopathy (swelling of the lymph nodes), back
pain, myalgia (muscle aches) and intense asthenia (lack of energy).
Lymphadenopathy is a distinctive feature of monkeypox compared to other
diseases that may initially appear similar (chickenpox, measles,
smallpox)
- the skin eruption usually begins within 1-3 days of
appearance of fever. The rash tends to be more concentrated on the face
and extremities rather than on the trunk. It affects the face (in 95% of
cases), and palms of the hands and soles of the feet (in 75% of cases).
Also affected are oral mucous membranes (in 70% of cases), genitalia
(30%), and conjunctivae (20%), as well as the cornea. The rash evolves
sequentially from macules (lesions with a flat base) to papules
(slightly raised firm lesions), vesicles (lesions filled with clear
fluid), pustules (lesions filled with yellowish fluid), and crusts which
dry up and fall off. The number of lesions varies from a few to several
thousand. In severe cases, lesions can coalesce until large sections of
skin slough off.
Monkeypox is usually a self-limited
disease with the symptoms lasting from 2 to 4 weeks. Severe cases occur
more commonly among children and are related to the extent of virus
exposure, patient health status and nature of complications. Underlying
immune deficiencies may lead to worse outcomes. Although vaccination
against smallpox was protective in the past, today persons younger than
40 to 50 years of age (depending on the country) may be more susceptible
to monkeypox due to cessation of smallpox vaccination campaigns
globally after eradication of the disease. Complications of monkeypox
can include secondary infections, bronchopneumonia, sepsis,
encephalitis, and infection of the cornea with ensuing loss of vision.
The extent to which asymptomatic infection may occur is unknown.
The
case fatality ratio of monkeypox has historically ranged from 0 to 11 %
in the general population and has been higher among young children. In
recent times, the case fatality ratio has been around 3-6%.
Diagnosis
The
clinical differential diagnosis that must be considered includes other
rash illnesses, such as chickenpox, measles, bacterial skin infections,
scabies, syphilis, and medication-associated allergies. Lymphadenopathy
during the prodromal stage of illness can be a clinical feature to
distinguish monkeypox from chickenpox or smallpox.
If monkeypox
is suspected, health workers should collect an appropriate sample and
have it transported safely to a laboratory with appropriate capability.
Confirmation of monkeypox depends on the type and quality of the
specimen and the type of laboratory test. Thus, specimens should be
packaged and shipped in accordance with national and international
requirements. Polymerase chain reaction (PCR) is the preferred
laboratory test given its accuracy and sensitivity. For this, optimal
diagnostic samples for monkeypox are from skin lesions – the roof or
fluid from vesicles and pustules, and dry crusts. Where feasible, biopsy
is an option. Lesion samples must be stored in a dry, sterile tube (no
viral transport media) and kept cold. PCR blood tests are usually
inconclusive because of the short duration of viremia relative to the
timing of specimen collection after symptoms begin and should not be
routinely collected from patients.
As orthopoxviruses are
serologically cross-reactive, antigen and antibody detection methods do
not provide monkeypox-specific confirmation. Serology and antigen
detection methods are therefore not recommended for diagnosis or case
investigation where resources are limited. Additionally, recent or
remote vaccination with a vaccinia-based vaccine (e.g. anyone vaccinated
before smallpox eradication, or more recently vaccinated due to higher
risk such as orthopoxvirus laboratory personnel) might lead to false
positive results.
In order to interpret test results, it is
critical that patient information be provided with the specimens
including: a) date of onset of fever, b) date of onset of rash, c) date
of specimen collection, d) current status of the individual (stage of
rash), and e) age.
Therapeutics
Clinical care for
monkeypox should be fully optimized to alleviate symptoms, manage
complications and prevent long-term sequelae. Patients should be offered
fluids and food to maintain adequate nutritional status. Secondary
bacterial infections should be treated as indicated. An antiviral agent
known as tecovirimat that was developed for smallpox was licensed by
the European Medical Association (EMA) for monkeypox in 2022 based on
data in animal and human studies. It is not yet widely available.
If
used for patient care, tecovirimat should ideally be monitored in a
clinical research context with prospective data collection.
Vaccination
Vaccination
against smallpox was demonstrated through several observational studies
to be about 85% effective in preventing monkeypox. Thus, prior smallpox
vaccination may result in milder illness. Evidence of prior vaccination
against smallpox can usually be found as a scar on the upper arm. At
the present time, the original (first-generation) smallpox vaccines are
no longer available to the general public. Some laboratory personnel or
health workers may have received a more recent smallpox vaccine to
protect them in the event of exposure to orthopoxviruses in the
workplace. A still newer vaccine based on a modified attenuated vaccinia
virus (Ankara strain) was approved for the prevention of monkeypox in
2019. This is a two-dose vaccine for which availability remains limited.
Smallpox and monkeypox vaccines are developed in formulations based on
the vaccinia virus due to cross-protection afforded for the immune
response to orthopoxviruses.
Prevention
Raising
awareness of risk factors and educating people about the measures they
can take to reduce exposure to the virus is the main prevention strategy
for monkeypox. Scientific studies are now underway to assess the
feasibility and appropriateness of vaccination for the prevention and
control of monkeypox. Some countries have, or are developing, policies
to offer vaccine to persons who may be at risk such as laboratory
personnel, rapid response teams and health workers.
Reducing the risk of human-to-human transmission
Surveillance
and rapid identification of new cases is critical for outbreak
containment. During human monkeypox outbreaks, close contact with
infected persons is the most significant risk factor for monkeypox virus
infection. Health workers and household members are at a greater risk
of infection. Health workers caring for patients with suspected or
confirmed monkeypox virus infection, or handling specimens from them,
should implement standard infection control precautions. If possible,
persons previously vaccinated against smallpox should be selected to
care for the patient.
Samples taken from people and animals with
suspected monkeypox virus infection should be handled by trained staff
working in suitably equipped laboratories. Patient specimens must be
safely prepared for transport with triple packaging in accordance with
WHO guidance for transport of infectious substances.
The
identification in May 2022 of clusters of monkeypox cases in several
non-endemic countries with no direct travel links to an endemic area is
atypical. Further investigations are underway to determine the likely
source of infection and limit further onward spread. As the source of
this outbreak is being investigated, it is important to look at all
possible modes of transmission in order to safeguard public health. Further information on this outbreak can be found here
Reducing the risk of zoonotic transmission
Over
time, most human infections have resulted from a primary,
animal-to-human transmission. Unprotected contact with wild animals,
especially those that are sick or dead, including their meat, blood and
other parts must be avoided. Additionally, all foods containing animal
meat or parts must be thoroughly cooked before eating.
Preventing monkeypox through restrictions on animal trade
Some
countries have put in place regulations restricting importation of
rodents and non-human primates. Captive animals that are potentially
infected with monkeypox should be isolated from other animals and placed
into immediate quarantine. Any animals that might have come into
contact with an infected animal should be quarantined, handled with
standard precautions and observed for monkeypox symptoms for 30 days.
How monkeypox relates to smallpox
The
clinical presentation of monkeypox resembles that of smallpox, a
related orthopoxvirus infection which has been eradicated. Smallpox was
more easily transmitted and more often fatal as about 30% of patients
died. The last case of naturally acquired smallpox occurred in 1977, and
in 1980 smallpox was declared to have been eradicated worldwide after a
global campaign of vaccination and containment. It has been 40 or more
years since all countries ceased routine smallpox vaccination with
vaccinia-based vaccines. As vaccination also protected against monkeypox
in West and Central Africa, unvaccinated populations are now also more
susceptible to monkeypox virus infection.
Whereas smallpox no
longer occurs naturally, the global health sector remains vigilant in
the event it could reappear through natural mechanisms, laboratory
accident or deliberate release. To ensure global preparedness in the
event of reemergence of smallpox, newer vaccines, diagnostics and
antiviral agents are being developed. These may also now prove useful
for prevention and control of monkeypox.
WHO response
WHO
supports Member States with surveillance, preparedness and outbreak
response activities for monkeypox in affected countries. More
information can be found
here https://www.who.int/news/item/20-05-2022-who-working-closely-with-countries-responding-to-monkeypox
