The Polio Eradication Programs have failed!

The outbreak of Polio is alarming. The Polio Eradication programs led by the WHO just focused on the administration of oral polio vaccines. However, that was not enough. The recent reports of poliovirus infection are scary. Previously, only three countries were considered to be Polio endemic. These included Afghanistan, Pakistan, and Nigeria. In 2019, eleven countries have reported Polio cases. Among the eleven countries, Pakistan has reported the highest number of cases. A list of the number of Wild Poliovirus cases from Pakistan is mentioned here:
  • In 2017:

    • The number of confirmed polio cases were 08
  • In 2018:

    • The number of polio cases increased to 12
  • In 2019:

    • The total confirmed cases until now is 110 (as of December 14th, 2019).
More than 2/3rd of the total polio cases in 2019 have been reported from the Khyber-Pakhtunkhwa province.

Here is a detail of the cases from each of the province:

  • Total cases from Balochistan: 07

    • District Harnai: 01
    • District Jaffarabad: 02
    • District Qila Abdullah: 03
    • District Quetta: 01
  • Total cases form Punjab: 05

    • District Jhelum: 01
    • District Lahore (City): 04
  • Total cases form Khyber Pakhtunkhwa: 73

    • District Bannu: 24
    • District Charsadda: 01
    • District D.I.Khan: 02
    • District Hangu: 02
    • District Lakki Marwat: 22
    • District Swabi: 01
    • District Shangla: 01
    • District Tank: 02
    • District Torghar: 07
    • District Bajaur: 01
    • District Khyber: 01
    • District North Waziristan: 08
    • District South Waziristan: 01
  • Total cases form Sindh: 22

    • District Hyderabad: 02
    • District Jamshoro: 02
    • Karachi: 06
    • Gulshan Iqbal: 01
    • Jamshed Town: 01
    • Kemari Town: 01
    • Layar: 01
    • Orangi: 02
    • District Larkana: 02
    • District Mirpurkhas: 02
    • District Sujawal: 01
    • District Benazirabad: 01
  • Most Recent Cases reported as on 14-Dec-19

    • District Swabi (KP): 01
    • District Mirpurkhas (Sindh): 02

Globally, the cVDPV is becoming a threat to Polio Eradication!

Globally, the number of cases reported that have been caused by the Wildpolio virus is 116. All these cases have been reported from the endemic areas. 22 cases paralytic polio have been reported from Afghanistan and the rest that is 94 cases have been reported from Pakistan. 227 out of a total of 343 cases have been reported globally to be caused by cVDPV (circulating Vaccine derived poliovirus). 29 of the 227 cases caused by cVDPV have been reported from the endemic polio countries while 198 cases have been reported from non-endemic countries.

Here is a table of the affected countries (as of 11th December 2019):

Country

cases of WPV

cases of cVDPV

Afghanistan

22

0

Angola
0
73
Benin
0
6
Central African Republic
0
16
Chad
0
1
China
0
1
Democratic Republic Of The Congo
0
61
Ethiopia
0
5
Ghana
0
10
Myanmar
0
6
Niger
0
1
Nigeria
0
18

Pakistan

94

11

Philippines
0
10
Somalia
0
3
Togo
0
3
Zambia
0
1
 

How Polio affects an individual? 

Polio is a viral infection that affects mostly children. It is transmitted via the fecal-hand-oral route (fecal-oral transmission). Up to 90 % of the Polio infections are asymptomatic. It has an incubation period of 7 - 14 days. Asymptomatic individuals develop transient mild viremia. 5 - 10% of infected individuals develop moderate to severe Polio virus viremia. Among those who develop moderate to severe viremia, most patients present with symptoms of viral pharyngitis such as headache, nausea, vomiting, fatigue, and malaise. This is called as abortive polio infection. The central nervous system is affected in a minority of the patients who develop abortive polio that manifests as headache, fever, vomiting, neck pain and tenderness. Up to 0.1% of the infected patients develop the paralytic polio. This is manifested by backache, stiffness, and limb weakness. The paralytic polio occurs when the virus affects the anterior horn cells of the motor neurons.

How does the paralytic polio infection manifest?

Patients develop weakness of the limbs that may vary from one muscle or group of muscles to involvement of all the limbs and respiratory failure. The muscles are usually involved in an asymmetric manner.

The patients have hypotonia that is the muscles become flaccid. The proximal muscles that are the thighs and shoulders are usually affected more than distal muscles, and the legs are affected more commonly than the arms.

Sensations are usually preserved and the reflexes are either decreased or absent. Some patients may develop the involvement of the bulbar muscles.

These patients develop drooling of saliva, dysarthria, and dysphagia. The symptoms may worsen over 2 - 3 days up to a week.

Since there is no treatment, prevention via vaccination is the key!

Before discussing the vaccination, it should be emphasized that a hygienic environment, clean water, and food are the primary factors and are as important as vaccination. However, because of the concerns of cVDPV, the government may need to switch to the safe alternatives of injectable polio vaccines. The OPV (oral polio vaccine) causes polio in one out of 2.5 million doses. However, it can be easily administered and may provide herd immunity. The OPV is, therefore, the preferred vaccine in polio-endemic countries. In non-endemic countries like in Europe and the United States, the Salk IPV is commonly administered.

Who should not be given the OPV (oral polio vaccine):

Since the OPV (oral polio vaccine) is a live attenuated vaccine, patients who are immunocompromised should not be administered the OPV vaccine. These include:
  • Patients with HIV infection and AIDS (acquired immunodeficiency syndrome)
  • Very low birth weight infants
  • Those with Immunodeficiency
  • Patients with sepsis or other serious condition
These patients should be preferably given the IPV vaccine which is an inactivated or killed vaccine.

Polio vaccination schedule:

OPV (oral polio vaccine) plus IPV (injectable polio vaccine) for Polio eradication in endemic areas:

  • WHO updated vaccination schedule recommends the addition of at least one dose of injectable polio vaccine for all countries using OPV in the national immunization program.
  • In polio-endemic countries like Pakistan and Afghanistan and in countries at high risk for importation and subsequent spread of poliovirus, WHO recommends:
    • a bOPV (bivalent Oral polio vaccine) birth dose (zero dose) followed by a primary series of 3 bOPV doses and at least 1 IPV dose.
  • The zero dose of bOPV should be administered at birth, or as soon as possible after birth, to maximize seroconversion rates following subsequent doses and to induce mucosal protection.
  • The primary series consisting of 3 bOPV doses plus 1 IPV dose can be initiated from the age of 6 weeks with a minimum interval of 4 weeks between the bOPV doses.
  • If 1 dose of IPV is used, it should be given at 14 weeks of age or later and can be co-administered with a bOPV dose.
  • The primary series can be administered according to the regular schedules of national immunization programs, e.g. at 6, 10, and 14 weeks (bOPV, bOPV, bOPV+IPV), or at 2, 4, and 6 months.
  • Both OPV and IPV may be co-administered with other infant vaccines.
  • Other vaccines that are administered at birth include the BCG and Hepatitis B vaccine.

IPV-only schedule (not used in endemic countries for polio eradication)

  • An IPV-only schedule may be considered in countries with sustained high vaccination coverage and very low risk of both WPV importation and transmission.
  • A primary series of 3 doses of IPV should be administered beginning at 2 months of age.
  • If the primary series begins earlier (e.g. with a 6, 10 and 14-week schedule) then a booster dose should be given after an interval of ≥6 months (for a 4-dose schedule).

In conclusion:

Polio eradication may not be possible if new mutant strains develop. The cVDPV is a major concern and IPV might be the only option in the non-polio-endemic areas to avoid the resurgence of the disease.