Specialists explain how monkeypox is transmitted and how to prevent it

Mexico has reported 9 confirmed cases of monkeypox, of which 4 have been located in Mexico City and 5 in Jalisco, informed virologist José Ángel Regla Nava, a researcher at the University Center of Health Sciences (CUCS) of the University of Guadalajara. The specialist participated in a press conference to announce the integration of the Situation Room for the Permanent Prevention and Promotion of Health, and to inform the population about the outbreak of this type of smallpox.

The first case in Jalisco corresponded to a 48-year-old male, foreigner, who stayed in Puerto Vallarta at Beach Club events from May 27 to June 4; case number 2 corresponds to a 40-year-old male, foreigner, and resident of Puerto Vallarta; case number 3 was a 46-year-old male, Mexican, who had contact with a visitor from Las Vegas and was in Guayabitos beach, Nayarit; Case 4 is a 38-year-old male, Mexican nationalized, resident of the Guadalajara Metropolitan Area (AMG), who has as epidemiological antecedent a visit to Puerto Vallarta from May 27th to 30th and the fifth case is a 48-year-old male, originally from Sweden, who visited Puerto Vallarta since June 9th.

On May 28, 2022, Mexico reported the first case of simian smallpox imported by a permanent resident of New York, a 50-year-old man, with a history of travel to Holland. The disease has an incubation period of seven to 14 days, ranging from five to 21 days. People do not spread the disease during this period, and it can last from two to four weeks.

Early symptoms of monkeypox

The presence of fever, exhaustion, chills, rash, muscle pain, back pain, cephalalgia (headache), and a very marked feature is swollen lymph nodes.

And the main signs and symptoms of the disease may appear after one to three days after the incubation period. Some rashes start on the face and spread to the rest of the body.

The first lesions may be on the tongue and mouth (enanthema), and after one or two days there is the presence of a macule (small reddened spots), which becomes a papule (small raised, solid bump on the skin with a distinct border that is easily seen) and then a vesicle; then after five to seven days they become pustules, and then there is a scab. When all the scabs fall off, the person is no longer contagious.

The simian pox virus is not new, it is a zoonotic disease discovered in 1958 in the city of Copenhagen in apes used for research. The first cases were transmitted by rodents, squirrels, and prairie dogs; however, recently, person-to-person transmission has been observed. The first human case of simian smallpox was reported in 1970 in the Democratic Republic of Congo.

There are two variants of the virus, and the severity of the disease may depend on the initial health of the individual, the route of exposure, and the variant of the infecting virus. The West African variant is associated with milder disease, fewer deaths, and limited person-to-person transmission; in contrast, the Central African variant usually results in more severe cases and higher mortality.

Fortunately, massive sequencing analyses carried out by several research groups in Portugal, the United States, and Spain, among other countries, have confirmed that the virus causing the outbreaks currently belongs to the West African variety, i.e., the prognosis is more optimistic.

In West Africa, the mortality rate is less than 1 percent; in the case of Central Africa, it is approximately 11 percent; both are not comparable with those of human smallpox, already eradicated, which reached up to 30 percent.

The good news is that so far no deaths have been reported in association with the latest smallpox outbreaks.

People who were vaccinated against human smallpox up to 1972 have 85 percent protection against monkeypox; therefore, if they are infected, it is expected that the symptoms will be brief and they will not present a severe case of the disease. After 1972, the human smallpox vaccine was discontinued throughout the country, except for some entities that had remnants of the vaccine.

Mechanisms of transmission of monkeypox

Dr. Juan Carlos Lona Reyes, pediatric infectologist, coordinator of the Pediatrics specialty of the CUCS at the Hospital Civil de Guadalajara (HCG) Dr. Juan I. Menchaca, explained that the mechanism by which infection is acquired from other species to humans is by scratching or biting.

Person-to-person transmission can be caused by contact with dermal lesions, body fluids, or contaminated surfaces, such as bedding. In this scenario, the persons at greatest risk of acquiring the infection will be household contacts, if there is a sick person or close contacts outside the home with a sick person.

There may be transmission by respiratory secretions; however, close contact is required. In international trips that may last many hours, so far no contagion has been reported, but in any case, in people who are not infected, the use of masks is recommended.

It has been said that sexual intercourse is a probable mechanism of transmission of the infection, but this possibility is under study and more information is needed to endorse it as an effective mechanism of transmission of the disease.

Other preventive measures for contact with people who may be infected include frequent hand washing, avoiding contact with contaminated surfaces or materials, and keeping patients in isolation when the disease is confirmed in them.

The illness may last from two to four weeks. There may be some serious complications due to bacterial superinfections that may occur, such as sepsis, bronchopneumonia processes, and encephalitis, among others.

Patients at risk of complications are those who have cancer and receive chemotherapy; HIV patients, children, and pregnant women.

Vaccines and PCR against monkeypox

There are vaccines, but they are not available for the general population, and the recommendation regarding vaccines will depend on the evolution of the alert. The Rector of the CUCS, Dr. José Francisco Muñoz Valle, said that the UdeG can perform the PCR test to detect simian smallpox; however, the recommendation is that the samples are sent directly to the state laboratory, in the case of Jalisco.

"Since the previous weeks, we have been performing different assays to be able to standardize this test, since to make a diagnosis we must be certain that we are amplifying a fragment of the simian smallpox virus gene itself. We have the conditions in the Laboratory of Emerging Diseases of the CUCS to make the diagnosis, but at this moment only the samples sent to the state laboratory are considered valid", declared Muñoz Valle.